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Authors: Joyce Theisen, Patricia Schuffenhauer, and Marsha Tharakan DDS, MD Abstract Objective: To evaluate the effects of a reviving cream on skin firmness, elasticity, wrinkle reduction, and barrier repair function.Methods: This open, intra-individual study involved 33 female subjects aged 20-60 years. Measurements were taken at baseline, day 14, and day 28 using Cutometer® for firmness/elasticity (face), PRIMOS-CR® 45 for wrinkle analysis (face), and Tewameter® for barrier function assessment (forearm). Barrier function was evaluated through tape stripping with treated and non-treated zones.Results: After 28 days, statistically significant improvements were observed in skin firmness (F4: -11%, p<0.0001; R0: -6%, p=0.0124) and elasticity parameters (R2: +5%, p=0.0004; R5: +6%, p=0.0024; R7: +5%, p=0.0042). Wrinkle parameters showed statistically significant reductions (Pz: -6%, p=0.0277; Rz: -6%, p=0.0068; Rt: -8%, p=0.0010). For barrier function, the cream demonstrated statistically significant improvement in TEWL compared to non-treated zones at 2 hours (-14%, p<0.0001) and 8 hours (-16%, p<0.0001) after single application. After 7 days, treated zones showed statistically significantly better barrier recovery compared to non-treated zones (-19%, p<0.0001).Conclusion: The reviving cream demonstrated significant efficacy in improving skin firmness and elasticity, reducing wrinkle parameters, and enhancing skin barrier function through both immediate and long-term recovery effects.Keywords: skin firmness, wrinkles, barrier function, clinical study, cosmetic efficacy. See Publication on American Academy of Dermatology Association: https://eposters.aad.org/abstracts/75454 

Medically reviewed by Dr. Adam J. Friedman. Professor and Chair of Dermatology, George Washington School of Medicine and Health Sciences, Washington, DC ________________________________________________________________________________________________ The epidermis—and in particular its outermost layer, the stratum corneum—contributes much of the barrier function of the skin and is a readily visible representation of skin health (Marieb 2019). Maintaining the health of the skin barrier has arguably become more important than ever in the modern world, in which a large majority of people are exposed to environmental chemicals (Quinovic 2021; CDC 2021). These external factors can damage the integrity of the skin barrier and promote premature aging of the skin (Roberts 2021; Schachner 2023). Thus, maintaining and protecting the stratum corneum has become increasingly important.Here, we briefly review the complex, multilayered structure of the skin and relate it to clinically translatable function, with an emphasis on the stratum corneum. In the context of epidermal structure and function, the formulation and clinical data for Phelityl® Reviving Cream will be reviewed.Skin Homeostasis: A Brief Review of Skin Barrier Structure and FunctionThe functionality of the epidermis extends far beyond simply forming an interface between the body and the environment, with roles in sensation, maintaining water content, defending against and responding to infection, photoprotection, and responding to and ameliorating oxidative stress, along with crucial regulatory, metabolic, and excretory functions (Lopez-Ojeda 2022). Among all of the body’s organs, the skin is the first point of contact and is most exposed to environmental insult from microorganisms, physical injury, temperature extremes, chemical pollution, and ultraviolet (UV) light. Its remarkable ability to self-repair is an essential element of healthy skin function for people of all ages, and progressive compromise of the skin barrier is common as individuals age, as well as in patients with dermatologic and certain systemic disorders (Roberts 2021). The most superficial layer of the epidermis—and the one that is largely responsible for the appearance of the skin to the observer and the main contributor to the skin barrier function—is the stratum corneum (Marieb 2019) (Figure 1). Only 10 to 20 µm thick, (Sandby-Møller 2003), the stratum corneum is composed of up to 30 layers of metabolically inactive, keratin-filled corneocytes that are shed at a rate approaching 50,000 cells per minute (Marieb 2019). The spaces between these cells are filled with a lipid-laden extracellular matrix. Far from being just a dead, dry layer, the healthy stratum corneum also contains about 20% to 25% water under average conditions, with water content changing dynamically in response to the humidity of the environment and the use of topical products (Murthy 2010). Figure 1.Epidermal Structure Focus on the Stratum CorneumThe stratum corneum has a “brick-and-mortar” composition, with the corneocytes forming the bricks and the extracellular matrix forming the mortar (Figure 2) (Kim 2020). The corneocytes are connected by corneodesmosomes that contribute to its resistance to mechanical stressors and selective permeability (Kim 2020). It is primarily composed of protein (75%-80%) and is rich in a variety of lipids that provide structural support and act as a barrier (Knox 2021). The extracellular space is a mixture of ceramides, cholesterol, and non-esterified fatty acids in approximately a 3:1:1 ratio (Knox 2021; Del Rosso 2011). Collectively, the relative composition of these lipids is critical for maintaining skin hydration and regulating transepidermal water loss (TEWL) (Del Rosso 2011).   Figure 2. "Brick-and-Mortar" Structure of the Stratum Corneum (Harding 2004) Ceramides constitute about half of the stratum corneum lipids (Knox 2021). These molecules consist of an amino acid–containing sphingoid base linked to a hydrophobic fatty acid chain (Knox 2021). They play a critical role not only in forming the lamellar barrier of the skin, maintaining skin moisture, and preventing ingress of microbes, but also act intracellularly as second messengers for a broad range of processes (Cha 2016). Cholesterol constitutes about one-quarter of lipids in the stratum corneum (Knox 2021). It maintains the fluidity and rigidity of cell membranes and is, along with ceramides, critical for the barrier function of the stratum corneum (Knox 2021). Fatty acids, most but not all of which are synthesized de novo by keratinocytes, comprise an additional 10% to 15% of the stratum corneum lipid content (Del Rosso 2011; Khynykin 2011). These compounds are known to modulate skin-surface pH, helping it maintain its natural acidity, and to contribute to the regulation of permeability, the antimicrobial properties of the skin, and the inflammatory response (Khynykin 2011). In addition to the fatty acids synthesized by keratinocytes, the essential fatty acids (EFAs) linoleic acid and α-linolenic acid are critical elements of both the epidermis and dermis. These essential compounds are unique among the fatty acids in that they must be supplied by the diet or exogenously by topical application and are the parent compounds for more than 30 derivatives that are critical for healthy skin, as illustrated by early studies showing that deficiencies manifest as dermatitis and increased TEWL (Prottey 1975; Hansen 1958)Along with ceramides, fatty acids, and cholesterol, the stratum corneum contains natural moisturizing factor, which is a mixture of small, water-soluble compounds derived from filaggrin, sweat constituents, and triglyceride turnover in the sebaceous glands (Gunnarsson 2021). These compounds make up approximately 10% of the dry weight of corneocytes and include a range of amino acids and amino acid derivatives, including pyrrolidone carboxylic acid, urocanic acid, lactic acid, sugars, urea, glycerol, and various ions (Gunnarsson 2021). Lipids supplied by the sebum—produced by sebaceous glands—are also present on the skin surface. Sebum consists of squalene, triacylglycerols, and wax esters and is present at the highest levels on the forehead, upper chest, and upper back (Knox 2021). Squalene, an intermediate in cholesterol biosynthesis, is a particularly potent natural emollient that is efficiently absorbed deep into the skin, maintaining its suppleness and flexibility (Huang 2009). Squalene also has a protective role, quickly neutralizing free radicals and protecting the skin against oxidative damage (Huang 2009).Normal Functions of the Stratum CorneumThe main functions of the stratum corneum include providing a selectively permeable barrier, protecting against UV light, serving as the first line of defense against pathogens and initiating the immune response to these microorganisms, quenching free radicals, and serving as a home for a diverse array of commensal skin microbiota.Barrier and homeostatic functions: The most commonly understood function of the skin is to act as a selectively permeable physical barrier between theinternal and external environment. The multiple layers of corneocytes that comprise the bricks of the stratum corneum, together with the glycolipids that serve as the mortar, maintain proper cutaneous water balance by preventing excess TEWL (Woodby 2020). Healthy skin is critical for maintaining body temperature to avoid uncontrolled water and solute loss (Marieb 2019).Photoprotection: The skin barrier is the primary site of exposure to UV radiation, and solar UV radiation (primarily UVA and UVB) is the primary driver of skin photoaging (Markiewicz 2019). Damage to the skin by UV radiation can be mediated by direct absorption of radiation by nuclear DNA, causing specific mutations in the skin genome. Indirect damage also may occur as a result of UV absorption into other skin constituents, the generation of reactive oxygen species, and the resulting formation of DNA photoproducts, in addition to characteristic alterations in cellular proteins and membranes (Markiewicz 2019). The skin contains an exquisite set of enzymatic pathways to continuously repair the damage caused by UV radiation and other environmental insults. Without proper care, the skin accumulates UV damage over time, leading to manifestations ranging from benign damage (wrinkling) to cancers (Markiewicz 2019). Antimicrobial functions: The stratum corneum is the first line of defense against many microbes and contains multiple mechanisms to prevent colonization by pathogens. It responds to those that manage to survive the harsh environment of the skin, and prime the downstream immune response. The first line of defense is the acid mantle—a pH that is maintained in healthy skin of between 5.4 and 5.9—a range that is inhospitable for many potential pathogens but is tolerated by commensal bacteria (Nguyen 2019). The skin also produces a number of antimicrobial peptides that can be present constitutively or produced in response to inflammatory stimuli (Nguyen 2019). The defensins and cathelicidins, which are produced by keratinocytes, sweat glands, and sebaceous glands, among other sites, and dermcidin, which is expressed by sebocytes, have broad bactericidal activity against microbes and also may play a role in initiating the immune response (Nguyen 2019). Certain skin lipids also have intrinsic antimicrobial activity against Staphylococcus aureus, Streptococcus pyogenes, and Propionibacterium acnes, among other bacterial species (Marieb 2019; Cartron2014; Nguyen 2019).Antioxidant: UV radiation, air pollution, and other environmental pollutants are well-understood to cause oxidative stress. After entering the skin as nanoparticles, air pollutants can produce reactive oxygen species that negatively impact the enzymatic and nonenzymatic activities of the skin and stimulate the release of proinflammatory mediators, among other negative effects (Roberts 2021). The skin contains an endogenous network of enzymatic and nonenzymatic systems to counter oxidative stress by quenching free radicals generated by environmental insults (Del Rosso 2011).Host to the skin microbiota: The skin also hosts a diverse array of bacteria, fungi, and viruses that collectively compose the skin microbiota, the composition of which varies substantially depending on the local physiology of the skin (Byrd 2018). Commensals on the skin surface actively prevent colonization by pathogenic microbes; furthermore, evidence suggests that there is crosstalk between the immune system and microbiota to assist in the maintenance of the normal microbial composition of the skin and eliminate pathogens (Byrd2018). The normal microbiota not only defends against potentially harmful microorganisms but can also produce substances that are directly beneficial for the skin. For example, data suggest that commensal Staphylococcus epidermidis produces protective ceramides that contribute to skin barrier homeostasis, and thus help to prevent skin dehydration and aging (Zheng 2022).Importance of Maintaining the Skin BarrierAs discussed, the skin barrier is both a multifunctional structure with critical roles in defending against environmental assault and homeostasis, as well as the structure that reflects our outward appearance to the world. Many of the functions of the epidermal barrier are the responsibility of the stratum corneum; thus, maintaining the stratum corneum is a priority for overall skin health. In addition to exogenous factors, aging has been shown to compromise the integrity of the stratum corneum, with changes in its biomechanical properties including stiffening of keratin fibers, increased cellular cohesion, and decreases in water movement through the stratum corneum (Biniek 2015). Levels of all 3 major classes of skin lipids—ceramides, cholesterol, and free fatty acids—also decline significantly with age, leading to compromise of the barrier function of the skin (Rogers 1996). Furthermore, the pH of the stratum corneum tends to increase with age, which has been shown to increase serine protease activity and reduce corneodesmosome density (Choi 2007).Several modifiable risk factors for poor skin barrier function can be readily addressed with appropriate routine skin care, including gentle cleansing and use of topical products designed to moisturize and support skin barrier function and avoiding unnecessary environmental exposure, the use of irritating topical products, and extended exposure to low-humidity environments (Del Rosso 2016). Conversely, without proper attention, the integrity of the stratum corneum can be compromised, leading to both visible and invisible manifestations such as dry, flaky skin, itching, and irritation.Phelityl® Reviving CreamThe science underlying the structure and function of the skin barrier was carefully considered in the development of Erno Laszlo’s Phelityl® Reviving Cream. Central to the product formulation is the Phelityl® Complex, a blend of botanical substances with evidencebased benefits on skin barrier health, which was combined with other ingredients to support the skin barrier and enhance hydration. Phelityl® Reviving Cream Key Components Phelityl® Complex Biobotanical blend Acacia gum biopolymer Plant-derived polyglycerides Rosehip oil Squalane Ceramides Red algae African tree and oleanolic acid blend Glycerin Phelityl® ComplexThe Phelityl® Complex is composed of a blend of botanical substances, including acacia gum biopolymers, plantderived polyglycerides, and rosehip oil, along with squalane and ceramides.Acacia gum (also known as gum Arabic) is an exudate gum produced by the Acacia senegal tree and a primary ingredient in Phelityl® Complex. Acacia gum is among the oldest substances used by humans, with the first recorded use over 5000 years ago. In clinical studies, acacia gum was shown to improve skin barrier and hydration (Data on File).The plant-derived polyglycerides and rosehip oil in the Phelityl® Complex each contribute EFAs to the formula. The mixture of polyglycerides is of 100% vegetable origin and includes oleic, linoleic, and linolenic fatty acids, the latter 2 of which are the parent fatty acids of the omega-6 and omega-3 series of EFAs (Linus Pauling 2024). Rosehip oil, an extract prepared from Rosa damasca, contains high amounts of essential polyunsaturated fatty acids derived from linoleic, linolenic, and arachidonic acids (Kutaitiene 2020).Squalene is a triterpene intermediate in the cholesterol biosynthesis pathway (Huang 2009). In humans, squalene is present in the highest concentrations in the skin, where it is produced in abundance by the sebaceous glands and constitutes approximately 13% of sebum (Huang 2009). Squalane, a hydrogenated derivative of squalene, is a powerful emollient and is absorbed into the skin, where it plays an important role in maintaining the suppleness and flexibility of the skin (Huang 2009). Beyond its emollient properties, squalane, sourced from renewable sugarcane, contributes to the ability of Phelityl® Reviving Cream to limit TEWL (Huang 2009).Finally, the Phelityl® Complex contains a ceramide blend. Ceramides are the predominant lipid in the stratum corneum and act to maintain skin moisture (Dragicevic 2015; Knox 2021).Additional Key Constituents of Phelityl® Reviving CreamPhelityl® Reviving Cream contains an extract from red algae (Porphyridium cruentum). The marine exopolysaccharide derived from this organism contributes to the long-lasting moisturizing properties of Phelityl® Reviving Cream, and its high molecular mass contributes to its film-forming properties, which together help to preserve and maintain skin hydration for extended periods (Data on File; Mourelle 2017; The Derm Review 2024).In addition to red algae, Phelityl® Reviving Cream contains a blend composed of extracts from the African Tree (Enantia chlorantha) in combination with oleanolic acid. In particular, extracts from this plant have been reported to regulate sebocyte differentiation and proliferation and to mildly inhibit 5α-reductase activity in the skin, leading to a reduction in sebum secretion (Data on file). Finally, glycerin, a natural humectant, contributes to the hydration of the stratum corneum and may protect against skin irritants (Milani 2017).Phelityl® Reviving Cream: Clinical Study ResultsThe effect of Phelityl® Reviving Cream on key skin parameters was evaluated in a study in which female subjects (N=31) aged 20 to 60 years who were predominantly of combination face skin type applied the product twice daily for 56 days.The use of Phelityl® Reviving Cream was associated with statistically significant improvements in a broad range of parameters, including skin barrier (TEWL), hydration, and sebum on the skin surface, while helping maintain a physiologic acidic skin pH (Data on file, Erno Laszlo 2024). Specifically, there were statistically significant results including a decrease in TEWL (P<0.0001), an increase in hydration (P<0.0001), and a decrease in skin surface sebum (P<0.0001) compared with baseline. The skin’s acidic pH was maintained with no change throughout the study. On the forearm portion of the study for assessing hydration, when comparing treated and untreated areas, there were statistically significant increases in hydration immediately after application (P<0.0001) and after 24 hours following a single application (P<0.0001). In the subject questionnaire, 97% of the subjects reported that their skin felt hydrated after use, 90% reported that the product left a soft matte finish, and all the subjects were satisfied with the results. ConclusionsComplex and multilayered, the skin performs a multitude of essential functions. The health of the stratum corneum is at considerable risk in today’s environment, with people exposed more than ever before to air pollution and environmental chemicals that can damage its structural and functional integrity (Roberts 2021; Schachner 2023). It is clear that preserving the epidermal barrier—the stratum corneum—is a priority for proper skin function and appearance. Carefully formulated topical products that have long-lasting moisturizing properties and can potentially optimize skin barrier health are an important way to support overall skin health. Phelityl® Reviving Cream is formulated with ingredients that have synergistic benefits that, together, help strengthen the skin barrier and maintain skin hydration. The effects of Phelityl® Reviving Cream were confirmed in a study in which Phelityl® Reviving Cream was shown to be associated with improvements in both immediateand long-term parameters, including a significant positive effect on the skin barrier and immediate and long-lasting hydration. Phelityl® Reviving Cream also had a statistically significant, effect on skin-surface sebum, consistent with subject reports that the product left a soft-matte finish to their skin. Together, these results indicate that Phelityl® Reviving Cream provides important skin benefits including supporting the skin barrier and enhancing hydration, to help maintain healthy looking skin.ReferencesBiniek K, Kaczvinsky J, Matts P, et al. Understanding age-induced alterations to the biomechanical barrier function of human stratum corneum. J Dermatol Sci. 2015;80:94-101.Byrd AL, Belkaid Y, Segre JA. The human skin microbiome. Nat Rev Microbiol. 2018;16:143-155.Cartron ML, England SR, Chiriac AI, et al. Bactericidal activity of the human skin fatty acid cis-6-hexadecanoic acid on Staphylococcus aureus. Antimicrob Agents Chemother. 2014;58:3599-609.Centers for Disease Control. Fourth National Report on Human Exposure to Environmental Chemicals. Updated tables, March 2021. Accessed March 12, 2024. https://ecologycenter.org/wp-content/uploads/2021/04/FourthReport_UpdatedTables_Volume2_Mar2021-508.pdfCha HJ, He C, Zhao H, et al. Intercellular and intercellular functions of ceramides and their metabolites in skin. Int J Mol Med. 2016;38:16-22.Choi E-H, Man M-Q, Xu P, et al. Stratum corneum acidification is impaired in moderately aged human and murine skin. J Invest Dermatol. 2007;127:2847-2856.Del Rosso J, Zeichner J, Alexis A, et al. Understanding the epidermal barrier in health and compromised skin: clinically relevant information for the dermatology practitioner: proceedings of an expert panel roundtable meeting.J Clin Aesthet Dermatol. 2016;9(4 suppl 1):S2-S8. Del Rosso JQ, Levin J. The clinical relevance of maintaining the functional integrity of the stratum corneum in both healthy and disease-affected skin. J Clin Aesthet Dermatol. 2011;4:22-42.Dragicevic N, Maibach HI, eds. Percutaneous Penetration Enhancers Chemical Methods in Penetration Enhancement: Drug Manipulation Strategies and Vehicle Effects. Springer; 2015:3-11.Gunnarsson M, Mojumdar EH, Topgaard D, et al. Extraction of natural moisturizing factor from the stratum corneum and its implication on skin molecular mobility. J Colloid Interface Sci. 2021;604:480-491.Hansen AE, Haggard ME, Boelsche AN, et al. Essential fatty acids in infant nutrition. III. Clinical manifestations of linoleic acid deficiency. J Nutr. 1958;66:565-576.Harding CR. The stratum corneum: structure and function in health and disease. Dermatol Ther. 2004:17(suppl 1):6-15.Huang Z-R, Lin Y-K, Fang J-Y. Biological and pharmacological activities of squalene and related compounds: potential uses in cosmetic dermatology. 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Content for this white paper was derived from an advisory board meeting of experts in epigenetics and/or skin aging as well as from the literature. This white paper was supported by Erno Laszlo, Inc. Advisory Board Meeting Participants and Affiliations Brian Capell MD, PhD (University of Pennsylvania), Raymond Cho MD, PhD (University of California at San Francisco), Manel Esteller MD, PhD (Josep Carreras Leukaemia Research Institute), Elena Eshkova PhD (Icahn School of Medicine at Mount Sinai), Taihao Quan MD, PhD (University of Michigan), Jouni Uitto MD, PhD (Thomas Jefferson University), Christos Zouboulis MD (Dessau Medical Center, Brandenburg Medical School Theodor Fontane) Introduction Genetic, environmental, and lifestyle factors interact to result in the accumulation of macromolecular damage and molecular deficits that manifest as aging. Studies of diseases of aging have definitively shown that genetic changes alter the behavior of cells; this process often begins with mutations that inactivate normal cellular mechanisms for monitoring the fidelity of DNA replication, resulting in the rapid accumulation of mutations in genes involved in controlling the growth and death of cells. Similarly, aging has long been known to be associated with the accumulation of mutations, leading to cellular dysfunction and, ultimately, to a senescent phenotype (Lee 2018). On the single-cell level, lifespan has been shown to decrease in a logarithmic fashion as mutation burden increases (Lee 2018). It has been increasingly recognized that other types of alterations in the genome, known as epigenetic changes, can modulate its structure and function without affecting the underlying DNA sequence. The term “epigenetics” was initially defined by Conrad Waddington in the 1940s, but in the modern context, it was formally defined in the 1990s by Wolffe and Matzkeset as “the study of heritable changes in gene expression that occur without a change in DNA sequence” (Alokail 2015). Epigenetic alterations, acting both independently and together with increasing mutational burden, genomic instability, and stem cell exhaustion, can influence gene expression in ways that promote aging (Saul 2021). Each of the 3 major epigenetic regulatory pathways—DNA methylation, chromatin dynamics (histone modifications), and expression of noncoding RNAs—has been shown to be associated with changes in cellular and organ functions as organisms age (Alokail 2015; Saul 2021). The skin, as the protective envelope of the body, is exposed to multiple environmental insults. Perhaps the most prominent of these is ultraviolet sun radiation. However, other factors such as pollution also have a profound impact on the structure and function of the skin. Recent data show that these extrinsic environmental factors synergize with intrinsic age-related changes to influence epigenetic regulation of gene expression, ultimately contributing to the visible—and invisible—signs of skin aging (Chevalier 2019). This white paper will first provide a brief refresher on the central paradigm of molecular biology, the rigorously controlled process by which genetic information flows within cells and biological systems. Subsequent sections focus on the epigenetic regulation of gene expression and its relevance to skin aging. 1. A REVIEW OF FUNDAMENTAL CONCEPTS IN MOLECULAR BIOLOGY It is important to have a fundamental understanding of how information flows from gene to protein to understand the role of epigenetics in aging. The Central Paradigm of Molecular Biology Setting aside sporadic mutations, every somatic cell in the body contains an identical genome with an identical complement of genes, each of which encodes a specific protein. However, cell types are differentiated by their program of gene expression. When a signal is sent to express a specific gene, the DNA sequence encoding that gene is used as a template to produce single-stranded RNA in a process called transcription. After transcription, the pre-mRNA transcript is spliced, joining coding exons together while excising introns and generating messenger RNA (mRNA), which is exported from the nucleus and read by ribosomes to produce polypeptides that fold into the final 3-dimensional structure of proteins (Figure 1.1). Although the DNA content of all somatic cells is identical, different cells appear and behave differently. Thus, gene expression must be tightly regulated so that only appropriate genes are expressed in a particular cell type. To accomplish this, the transcriptional unit is preceded by regulatory elements, such as promoters and enhancers, that modulate production of its protein encoding transcript (Figure 1.2). All protein-coding genes require a promoter, a regulatory element that is necessary to initiate the process of transcription. The core promoter is a short length of noncoding DNA that overlaps the transcription start site. Many genes have additional regulatory elements such as enhancers, repressors, or insulators (Allison 2017). Finally, epigenetic mechanisms can also play a role in the modification of gene expression and protein synthesis. Figure 1.1 Flow of genetic information in a cell Figure 1.2 A typical gene and regulatory regions (Allison 2017) Packaging of the Eukaryotic Genome The term “genome” refers to the totality of DNA in the nucleus. All DNA in the cell’s nucleus is organized into chromosomes—thread-like structures of nucleic acids and proteins. The human diploid genome contains approximately 6 billion base pairs. The total length of DNA is about 2 meters, all of which must be accommodated in the nucleus (Annunziato 2008). To accomplish the necessary compaction, negatively charged DNA is complexed with positively charged histones to form nucleosomes, each of which is composed of 8 histone proteins (2 copies each of H2A, H2B, H3, and H4) wrapped about 1.65 times by DNA. (Figure 1.3). Additional compaction is achieved by a series of folding and coiling steps, ultimately resulting in the chromatid of a chromosome. The compression and unwinding of DNA are tightly regulated through processes that can “tighten” or “loosen” chromatin, allowing regions of the genome to be accessed for transcription. 2. AN INTRODUCTION TO EPIGENETIC REGULATION OF GENE EXPRESSION Consider that all cells have the same DNA but organisms contain many different types of cells: skin cells, neurons, liver cells, pancreatic cells, inflammatory cells, and many others. The ability of many different cell types to be derived from the same instruction set—the cell DNA— is driven by differential gene expression. Therefore, different subsets of genes are expressed depending on cell type. Epigenetic mechanisms are one way in which gene expression programs are managed in a temporally and spatially appropriate manner to determine cell type, govern cellular behavior, and drive cells along specific differentiation pathways (Simmons 2008). Broadly, there are 3 epigenetic pathways that regulate gene expression: DNA methylation, histone modifications, and RNA-associated silencing (Simmons 2008). DNA methylation involves the addition of a methyl group to DNA. It primarily occurs in region tracts of DNA called CpG islands, where cytosine nucleotides alternate with guanine nucleotides. Figure 1.3 DNA is packaged in multiple steps to compress its 2-meter length into a structure that can fit into the cell nucleus (Annunziato 2008) Histone modifications involve posttranslational modifications that alter chromatin structure. Some of these “loosen” chromatin, allowing it to be accessed by transcriptional machinery. Other modifications condense chromatin into heterochromatin, which is not transcriptionally active. Acetylation and methylation are the primary, but not the only, epigenetic mechanisms governing chromatin dynamics. Genes can be silenced by antisense RNA. RNA may also affect gene expression by causing heterochromatin to form, triggering histone modifications, or by modulating DNA methylation. DNA Methylation Methylation of the DNA base cytosine is the major DNA modification in most animals and plants (Allison 2017). Cytosine DNA methylation is a covalent modification of DNA. In this reaction, a methyl group (CH3) is transferred from s-adenosylmethionine (SAM) to the carbon-5 position of cytosine by cytosine DNA methyltransferases (Dnmt). 5-methyl-cytosine is the only modified base in most cells (Allison 2017). DNA methylation occurs almost exclusively at the dinucleotide CG in mammals, often denoted as “CpG,” where p stands for the phosphate group. CpGs can occur in islands consisting of multiple CpG repeats. These islands are found in the promoter regions of about half of the genes in the human genome, where they are sparsely methylated. In contrast, 80% of CpGs outside these islands are heavily methylated (Alokail 2015). Importantly, methylation is maintained during DNA replication, so daughter cells retain the methylation patterns of the parent cell. After replication, the DNA double helix is hemimethylated—the template strand retains its original methylation pattern, and the newly synthesized strand is unmethylated. A maintenance DNA methyltransferase, DNMT1, recognizes only hemimethylated sites and methylates the new strand of DNA appropriately (Allison 2017). Methylation is usually, but not always, a way of marking genes for silencing, although the precise effect varies by the location of the methylated DNA region (Figure 2.1): (Aquino 2018) Methylation in the promoter region shuts off gene expression Methylation of the transcription initiation site also shuts off gene expression Methylation inside the protein-coding region gene is often correlated with increased gene expression Histone Modification Histone modifications are important in transcriptional regulation. DNA that is wrapped tightly around histones is not accessible to the transcription machinery. To make it accessible, the region wrapped around histones must “relax.” The compressed state is referred to as “heterochromatin” and the relaxed state as “euchromatin.” The transitions between heterochromatin and euchromatin are accomplished by enzymatic modification of histones. This process is tightly regulated to control gene expression and is highly tissue-specific, with each tissue displaying a characteristic pattern of transcriptionally accessible regions (Simmons 2008). The N-terminal tails of histones, which protrude from the core histone octamer, are subject to at least 6 different types of covalent modifications: acetylation, methylation, ubiquintinylation, phosphorylation, ADPribosylation, and sumoylation. These modifications control access to the DNA wrapped around the histone (Allison 2017). The enzyme histone acetyltransferase (HAT) adds up to 3 acetyl groups to ≥1 of the lysine residues in histone tails (Alokail 2015). The addition of a negatively charged acetyl group reduces the overall positive charge of histones, reducing the affinity of histone tails for negatively charged DNA. The action of HAT is countered by histone deacetylase (HDAC), which removes acetyl groups from lysine in histone tails. Acetylation of histones is generally associated with active regions of gene expression, while deacetylation generally correlates with regions of reduced gene expression (Simmons 2008). Methylation and demethylation are catalyzed by histone methyltransferases (HMTs) and histone demethylases (HDMs), respectively (Figure 2.2). Methylation of histones has a more complex set of outcomes than acetylation; while methylation of certain residues can suppress transcription, methylation of other residues may have an activating effect. Figure 2.1 The effects of DNA methylation vary by location (Aquino 2018) Figure 2.2 Methylation of histones can “relax” chromatin, allowing the transcriptional machinery to access DNA regions RNA-Associated Silencing As discussed earlier, mRNA carries genetic information from DNA to the ribosome, where it is translated to proteins and is thus referred to as coding RNA (RNA that codes for proteins). Large regions of the genome do not code for proteins and were long regarded as “junk” DNA. It was not until the 1990s that a role for this DNA was elucidated. Today, it is known that many types of RNA are transcribed from these DNA regions but are never translated into proteins. These RNAs—referred to collectively as noncoding RNAs—function as posttranscriptional epigenetic regulators of gene expression (Chhabra 2017). There are at least 5 classes of noncoding RNAs that play roles in mammalian cells, including but not limited to regulation of apoptosis, signaling, embryonic development, and tissue differentiation (Table 2.1).  Type Length Functions Number in Humans MicroRNA (miRNA) 19-24 mRNA degradation or repression of translation -2500 Short-interfering RNA (siRNA) 20-25 mRNA degradation Unknown Piwi interacting RNA (piRNA) 26-31 Transposon silencing, germline development -23,000 Small nucleolar RNA (snoRNA) 60-150 Modification of rRNA -400 Long noncoding RNA (lncRNA) >200 Chromatin reprogramming, precursors of small RNAs -120,000 Table 2.1 Classes of noncoding RNAs associated with epigentic phenomena (Chhabra 2017)   Figure 2.3 miRNA transcription, processing, and mechanism of action (Magri 2017) miRNAs are transcribed from DNA by RNA polymerase 2 and then undergo a number of processing steps before being loaded into the RNA-induced silencing complex, or RISC, which utilizes the noncoding RNA to recognize target sequences on mRNA. If the RISC complex encounters a perfectly complementary sequence, the target mRNA is cleaved. If the RISC complex has partial complementarity to the target, translation of the target mRNA is suppressed (Magri 2017, p 3A) (Figure 2.3). 3.THE EPIGENETICS OF SKIN AGING Skin Aging The skin is the largest organ of the body. Because it is continuously exposed to environmental insults, efficient and continuous replacement of its outer layers is critical for proper function. The epidermis is a relatively thin layer composed of epithelial cells that serves as a protective shield, while the underlying dermis—which makes up the bulk of the skin— is composed of dense, connective tissue penetrated by nerves and blood vessels from its lower side and skin appendages (pilosebaceous units and sweet glands) from its upper side. The epidermis itself has a layered structure characterized by progressive differentiation of cells as they move toward the surface. The stratum basale, the deepest layer of the epidermis, is composed of a single layer of undifferentiated epithelial cells, with a few progenitor cells among them, that continuously divide to produce differentiating keratinocytes. As these cells divide, they push cells upward to begin differentiation into keratinocytes and, ultimately, into the heavily keratinized anucleate corneocytes that form the stratum corneum. The dermis contains fibroblasts that produce an extracellular matrix composed of collagen, elastic fibers, glycoproteins, and proteoglycans, which together maintain skin architecture and confer elasticity, resistance, and strength to the tissue (Orioli 2018; Marieb 2015; Kang 2018). The cells of the epidermis and dermis are characterized by tightly controlled programs of gene expression. During epidermal self-renewal, each stem cell must choose between divisions that result in self-renewal or divisions that result in a daughter cell that is fated to undergo terminal differentiation (Zouboulis 2008). Once this choice has been made, a complex series of temporal and spatial changes in gene expression occur as the keratinocyte progressively differentiates and ultimately ejects its nucleus to become a heavily keratinized corneocyte (Orioli 2018). In the dermis, tightly regulated gene expression programs manage the maintenance of epidermal homeostasis, wound healing, and production of the extracellular matrix, among other activities. (Orioli 2018; Kang 2018) Both intrinsic and extrinsic factors synergize to produce skin aging (Zouboulis 2011; Figure 3.1). Young, healthy skin is characterized by a thick, well-organized dermal layer abundantly populated by fibroblasts producing elastic fibers and collagen. In aged skin, dermal fibroblasts become senescent, resulting in reduced production of elastic fibers and a loose, disorganized, and degraded collagen structure. Figure 3.1 Morphologic features of young, aged, and photoaged skin (Orioli 2018) At the same time, the epidermis thins, resulting in the appearance of wrinkles. As with intrinsic aging, extrinsic aging of the skin—such as that caused by photodamage or pollutants—is characterized by dermal atrophy. In contrast, photoaging is associated with a heterogeneously thickened epidermal layer that contributes to skin wrinkling (Orioli 2018). Role of Epigenetics in Skin Aging Modifications in all 3 epigenetic pathways—DNA methylation, chromatin dynamics, and RNA-based silencing—are seen in aging skin. Due to the sheer abundance of data on this topic, this section will only touch on some examples of changes in aging skin. Suggestions for further reading are provided at the end of this white paper for those interested in more detail. DNA Methylation DNA methylation patterns in epidermal and dermal tissue have been shown to change with aging. While methylation patterns are similar in young individuals, they display increasing divergence as organisms age, suggesting a role for environmental factors in modulating methylation marks (Orioli 2018). Increased methylation heterogeneity has been linked to cellular senescence, at least in vitro, and has been demonstrated in aging fibroblasts (Koch 2011). Expression of the DNA methyltransferase DNMT1 decreases as fibroblasts are sequentially passaged, and experimental silencing of DNMT1 in young fibroblasts induces a senescent phenotype (De Paoli-Iseppi 2017; Lopatina 2002; Wang 2017). Methylation patterns change over time in multiple genes implicated in dermal aging. For example, the TET2 gene is hypermethylated in epidermis samples from elderly individuals (Gronniger 2010). Recent data suggest that TET2, which is itself an epigenetic regulator, has roles in modulating cell viability, apoptosis, and the expression of inflammatory mediators in keratinocytes (Liu 2020). Similarly, DDAH2, an enzyme in the nitric oxide pathway, is hypermethylated in aging and chronically sun-exposed tissues (Gronniger 2010). Downregulation of DDAH2 may predispose the keratinocytes cell to accelerated oxidative damage. The evidence for an impact of extrinsic factors, such as ultraviolet radiation, on DNA methylation is inconsistent. Some studies have shown distinctive patterns of hyperand hypomethylation in photoaged tissues, while others have not demonstrated a consistent link (de Olivera 2020). Chromatin Dynamics Aging is associated with changes in chromatin organization. In particular, aging is associated with the replacement of canonical histones by histone variants. For example, the histone variant H2A.J—which differs by only a single amino acid from the canonical H2A histone—is expressed and incorporated into the chromatin of human fibroblasts during senescence, which allows the transcriptional machinery to constitutively access previously tightly regulated inflammatory genes (Contrepois 2017). Further, H2A.J is deposited in response to DNA damage induced by ionizing radiation (Isermann 2020). H3K27me3, denoting the addition of 3 methyl groups to lysine (K) 27 on histone H3, is currently the beststudied histone modification with a potential role in skin aging (Orioli 2018). This mark, which is associated with transcriptional suppression of nearby genes, is added by the methyltransferase Polycomb Repressor Complex (PRC) and removed by Jumonji family demethylases (Leon 2019). PRC manages epidermal stem cell identity and self-renewal by suppressing nonlineage, differentiation, and senescence genes; reduced expression of subunits of this complex have been linked to skin aging and senescence of both keratinocytes and fibroblasts (Perdigoto 2014; Sen 2008). PRC activity is directly affected by UVA radiation, resulting in reduced hyaluronic acid production by and senescence of human dermal fibroblasts (Orioli 2018). The Jumonji demethylases have also been strongly implicated in fibroblast senescence (Orioli 2018). Changes in histone acetylation over time are also strongly implicated in skin cell aging. The sirtuins (SIRTs 1–7) are nicotine adenine dinucleotide (NAD)-dependent enzymes involved in managing energy metabolism and oxidative stress, response to UV damage, and inflammation, among other activities. SIRTs 1–6 are involved in the deacetylation of histones, and they also regulate the acetylation status of transcription factors. SIRT1, in particular, has been shown to play critical roles in the regulation of skin homeostasis, including the induction of keratinocyte proliferation, inhibition of epidermal cell senescence, and stimulation of type 1 collagen in fibroblasts. SIRT1 expression is downregulated in aging epidermal tissues. SIRT6, which is thought to manage access of DNA repair proteins to chromatin, is also downregulated in aging keratinocytes and fibroblasts, resulting in increased susceptibility to DNA damage (Orioli 2018). RNA-Mediated Silencing While there are a number of different noncoding RNA species that play a role in gene regulation, at present, miRNAs are the best studied in aging. Differential expression of miRNAs has been demonstrated in aging tissues. In one study that evaluated miRNA expression in the whole blood of over 5000 adults, 127 miRNAs were identified that were differentially expressed based on age (Huan 2018). Of particular importance, the microRNA miR-217, which targets DNMT1 RNA, has been shown in vitro to promote senescence in human fibroblasts by suppressing DNMT1 expression (Wang 2017). In vivo, skin samples derived from patients of different ages showed that miR-217 expression was significantly upregulated in skin tissues from older ndividuals (Wang 2017). miRNAs play direct roles in the post-transcriptional regulation of extracellular matrix proteins, including but not limited to collagen type I and type IV, decorin, fibronectin, and epidermal growth factor (Maurer 2010; Kwan 2015; Shan 2009; Giles 2011). Many other miRNA-mediated regulatory pathways are important in aging-related gene networks. Members of the miR-30 family are overexpressed in skin aging. This family of microRNAs is associated with autophagy, a catabolic process involved in the degradation of worn, abnormal, or malfunctioning cellular components in lysosomes. Autophagy declines in effectiveness as tissues age and may allow for the accumulation of nonfunctional cellular debris that contributes to the aging process. Similarly, members of the miR-200 family are overexpressed in aging tissues. These miRNAs help regulate the oxidative balance and overexpression allows for the accumulation of reactive oxygen species, disturbing skin homeostasis, promoting DNA damage, and accelerating apoptosis. Finally, expression of the miR-181 family is induced in aging skin, where they act as repressors of SIRT1 and also disrupt mitochondrial function (Chevalier 2019). Other miRNAs may influence sebaceous lipogenesis, which generally declines with age (Schneider 2013). miRNA expression may be a critical link between UV exposure and skin aging. Exposure of cultured keratinocytes to UVB radiation results in >2-fold changes in the expression of 44 miRNAs (Zhou 2012). Further, miRNA expression is involved in the regulation of several aspects of the DNA damage response to promote cell survival after UV exposure. Experimental knockdown of components of the miRNA processing pathway was shown to compromise the checkpoint response and, ultimately, the survival of UV-exposed cells (Syed 2014). At least 5 miRNAs are upregulated in photo-aged skin, including miR-101, which silences translation of EZH2, a subunit of PRC (Greussing 2013; Syed 2014). 4. CONSIDERATIONS FOR PRODUCT DEVELOPMENT AND THE PHORMULA 3-10 COLLECTION As products are developed to address the appearance of skin, it is important to understand the science behind the signs of aging skin, including the contribution of epigenetics. At Erno Laszlo, we consider this science in the development of our products and in particular our new Phormula 3-10 line. These Phormula 3-10 products all contain Erno Laszlo’s proprietary complex, Epigene-6, and are formulated to minimize the appearance of aging by providing an optimal environment for the skin to repair itself. Epigene-6 encapsulates three key active ingredients, apple, ginger and niacinamide, to support skin exposed to environmental triggers and target the six signs of aging skin: wrinkles, elasticity, firmness, skin tone, skin hydration, and skin texture. The Phormula 3-10 line includes Phormula 3-10 Repair and Phormula 3-10 Eye Intensive products: Phormula 3-10 Repair is an advanced nurturing balm with Epigene-6, niacinamide and the skin conditioning Cera-Skin complex to provide a nourishing environment for the skin to accelerate the recovery of a compromised skin moisture barrier. It has been clinically tested and shown to significantly decrease the appearance of wrinkles, and improve elasticity, firmness, skin tone, skin moisture barrier, hydration and texture. Phormula 3-10 Eye Intensive is a multiaction eye cream with Epigene-6 as well as hawthorn and jasmine flower extracts to improve the appearance of fine lines and wrinkles. Phormula 3-10 Eye Intensive has also been clinically tested and shown to significantly decrease the appearance of wrinkles and eye bags while improving skin hydration around the eye area.  5. CONCLUSIONS Epigenetic mechanisms have long been understood to play a critical role in age-related diseases such as cancer, and treatments directed at modulating the activity of various elements of epigenetic pathways are becoming increasingly common in oncology. The skin is not only subject to intrinsic aging but is also exposed to numerous extrinsic insults. Data suggest that the confluence of these factors results in changes in the epigenetically controlled expression of genes that play roles in skin homeostasis. The disruption of these pathways likely contributes to the visible manifestations of aging. As products are developed, it is important to consider the science of aging. 6. FURTHER READING The role of epigenetics in skin aging is complex. For those who are interested and would like to read further, we recommend the following reviews. Chevalier FP, Croteau J, Lamartine J. MicroRNAs in the functional defects of skin aging. In: Noncoding RNAs. InTech Open. 2019. Orioli D, Dellambra E. Epigenetic regulation of skin cells in natural aging and premature aging diseases. Cells. 2018;7:1-30. Syed DN, Khan MI, Shabbir M, et al. MicroRNAs in skin response to UV radiation. Curr. Drug Targets. 2013;14:1128- 1134. REFERENCES Allison LA. Fundamentals of Molecular Biology. Malden, MA: Blackwell Publishing. 2017. Alokail MS, Alenad AM. DNA methylation. A Concise Review of Molecular Pathology of Breast Cancer. InTech Open. 2015. Annunziato A. DNA packaging: nucleosomes and chromatin. Nature Education. 2008;1:26. Aquino EM, Benton MC, Haupt LM, et al. Current understanding of DNA methylation and age-related disease. OBM Genetics. 2018;2. Chhabbra R. The epigenetics of noncoding RNA. In: Handbook of Epigenetics. Elsevier Inc. 2017. Chevalier FP, Croteau J, Lamartine J. MicroRNAs in the functional defects of skin aging. In: Noncoding RNAs. InTech Open. 2019. Contrepois K, Conderau C, Benayoun BA, et al. Histone variant H2A.J accumulates in senescent cells and promotes inflammatory gene expression. Nat. Commun. 2017;8:14995. de Olivera NFP, de Souza BF, Coelho MDC. UV radiation and its relation to DNA methylation in epidermal cells: a review. Epigenomes. 2020. de Paoli-Iseppi R, Deagle BE, McMahon CR, et al. Measuring animal age with DNA methylation: from humans to wild animals. Front. Genet. 2017;8:106-118. Giles KM, Barker A, Zhang PM, et al. MicroRNA regulation of growth factor receptor signaling in human cancer cells. Methods Mol. Biol. 2011;676:147-163. Gronniger E, Weber B, Heil O, et al. Aging and chronic sun exposure cause distinct epigenetic changes in human skin. PLOS Genetics. 2010;6:e1000971. Huan T, Chen G, Liu C, et al. Age-associated microRNA expression in human peripheral blood is associated with all-cause mortality and age-related traits. Aging Cell. 2018;17:e12687. Isermann A, Mann C, Rube CE. Histone variant H2A.J marks persistent DNA damage and triggers the secretory phenotype in radiation-induced senescence. Int. J. Mol. Sci. 2020;21:9130. Kang S, Chovatiya G, Tumbar T. Epigenetic control in skin development, homeostasis and injury repair. Exp Dermatol. 2019;28:453-463. Koch CM, Suchek CV, Lin Q, et al. Specific age-associated DNA methylation changes in human dermal fibroblasts. PLoS ONE. 2011;6:e16679. Kwan P, Ding J, Tredget EE. MicroRNA 181b regulates decorin production by dermal fibroblasts and may be a potential therapy for hypertrophic scar. PLOS One. 2015;10:e0123054. Lee MB, Dowsett IT, Carr DT, et al. Defining the impact of mutation accumulation on replicative lifespan in yeast using cancer-associated mutator phenotypes. PNAS. 2018;116:3062-3071. Leon KE, Aird KM. Jumonji C demethylases in cellular senescence. Genes (Basel). 2019;10:33-37. Liu X, Wang X, Liu N, et al. TET2 is involved in DNA hydroxymethylation, cell proliferation and inflammatory response in keratinocytes. Mol. Med. Rep. 2020;21:1941-1949. Lopatina N, Haskell JF, Andrews LG, et al. Differential maintenance and de novo methylating activity by three DNA methyltransferases in aging and immortalized fibroblasts. J. Cell. Biochem. 2002;84:324-334. Magri F, Vanoli F, Corti S. mRNA in spinal muscular atrophy pathogenesis and therapy. J. Clin. Mol. Med. 2018;22:755-767. Marieb EN, Hoehn K. Human Anatomy & Physiology. 10th ed. Pearson Educational Ltd. 2015. Maurer B, Stanczyk J, Jungel A, et al. MicroRNA-29, a key regulator of collagen expression in systemic sclerosis. Arthritis Rheum. 2010;62:1733-1743. Orioli D, Dellambra E. Epigenetic regulation of skin cells in natural aging and premature aging diseases. Cells. 2018;7:1-30. Perdigoto CN, Valdes VJ, Bardot ES, et al. Epigenetic regulation of epidermal differentiation. Cold Spring Harb. Perspect. Med. 2014;4:a015263. Saul D, Kosinsky RL. Epigenetics of aging and aging-associated disease. Int. J. Mol. Sci. 2021;22:1-25. Schneider MR, Samborski A, Bauersachs S, et al. Differentially regulated microRNAs during human sebaceous lipogenesis. J. Dermatol. Sci. 2013;70:88-93. Sen GL, Webster DE, Barragan DI, et al. Control of differentiation in a self-renewing mammalian tissue by the histone demethylase JMJD3. Genes Dev. 2008;22:1865-1870. Shan SW, Lee DY, Deng Z. MicroRNA MiR-17 retards tissue growth and represses fibronectin expression. Nat. Cell. Biol. 2009;11:1031-1038. Simmons D. Epigenetic influences and disease. Nature Education. 2008;1:6. Syed DN, Khan MI, Shabbir M, et al. MicroRNAs in skin response to UV radiation. Curr. Drug Targets. 2013;14:1128-1134. Wang B, Du R, Xiao X, et al. MicroRNA-217 modulates human skin fibroblast senescence by directly targeting DNA methyltransferase 1. Oncotarget. 2017;8:33475-33486. Zhou BR, Xu Y, Permatasari F, et al. Characterization of the miRNA profile in UVB-irradiated normal human keratinocytes. Exp. Dermatol. 2012;21:317-319. Zouboulis CC, Adjaye J, Akamatsu H, et al. Human skin stem cells and the ageing process. Exp. Gerontol. 2008;43:986-997. Zouboulis CC, Makrantonaki E. Clinical aspects and molecular diagnostics of skin aging. Clin. Dermatol. 2011;29:3-14.

Insights from Skin Wellness Visionary, Dr. Erno Laszlo > This clearly and simply states the mind-body connection between what we feel and how we look, and is a foundational component of psychodermatology, an emerging specialty in dermatology and psychiatry addressing interactions between the skin and mind.2 That statement could have been uttered by any of the physicians affiliated with the Association for Psychoneurocutaneous Medicine of North America (APMNA)3or the late Emiliano Panconesi, one of the founders of the European Society for Dermatology and Psychiatry (ESDaP).4 These organizations, both started in 1993, aim to improve patient care by putting insights gained from research in psychodermatology into practice. But in fact, it wasn’t. This statement was made nearly 50 years before these organizations existed by Dr. Erno Laszlo, a man who dedicated his life and career to helping people let their beauty within shine through their faces, and who knew the complexities of “the essential harmony between a woman’s outlook on her life and her appearance.”5 Psychodermatology, also called psychosomatic dermatology6 or psychocutaneous medicine,7 while long recognizing the link between the skin and the mind, is still considered an emerging field. When you think that back in 400 BC, Greek philosopher Plato lamented that “this is the great error of our day that in the treatment of the human being, the physicians separate the soul from the body,” one could wonder why it’s not the standard of care in 2021. A review of the literature shows that 85% of dermatology patients have indicated that the psychological aspects of their skin disease are a major component of their illness.8 Fortunately, the science of psychodermatology is finally coming into its own—a good thing for patients who struggle with skin conditions and anxiety or other stressors. Yet, the young Dr. Laszlo had many insights into these concerns when he established his practice in 1927 in Hungary. Let’s explore. The Early  Years His formative years, Dr. Laszlo worked under Max Joseph, a physician noted as the “father of modern dermatology.”9 Joseph observed that when the young Laszlo was away for travel, a good number of patients stopped coming; when he returned, so did they. Laszlo confided that he had embarked on prescribing new formulations based on his own research. Why, asked Joseph, what’s wrong with what we’re prescribing? The answer summed up what would define Dr. Laszlo’s world-renowned approach to skin care: “I observed and listened,” he said. At the time, dermatological science focused on the treatment of disease, with little focus on what the patient was experiencing. In contrast, Dr. Laszlo listened to his patients first. For example, to get to the cause of why their conditions weren’t improving, he asked patients about their routines and how they were using the prescribed treatments. Patients confessed that they stopped using the foul-smelling ointments once they got home. No wonder their conditions weren’t getting better! With this insight into his patients’ behavior, Laszlo then worked to create his own formulations that were scientifically robust while being more pleasant to use. This was an early insight into the need for ‘listening and learning about what’s not seen while observing what is.’ He listened again when asked by the Royal Court handlers of Princess Stephanie of Belgium to meet with her to address a skin condition, presumably acne, that kept her hidden indoors and away from all social contact—even to the point of jeopardizing her marriage. He listened deeply enough to discern her angst over feeling ‘not good enough’ for her role in society, while he examined her skin. Instead of the heavy purplish glop or white powders that were the treatments of the day, Dr. Laszlo created a preparation that treated the skin while being invisible. He called this “no make-up make-up,” an early version of what is known today as Shake-It Tinted Treatment. The purpose was to treat the underlying problems while allowing Princess Stephanie to feel more confident in her appearance. This was unchartered territory! During that time, women still relied on hiding the skin’s imperfections using methods of covering it up with thick make-up made popular in ancient Egyptian and Chinese cultures. Throughout his career, Dr. Laszlo was outspoken against the overuse of cosmetics to cover skin, often quoted in newspaper articles and speeches where he pleaded for an “educational campaign…[about how] the indiscriminate use of cosmetics on their faces can be worse for their skins than if they used nothing at all.”10 In the 1950s, he told his employees, “The old-fashioned theory of cosmetics as camouflage is out.”11 Much to Princess Stephanie’s good fortune, he persevered and with his tailored preparations and gentle coaching, and over time she built her confidence and took her place in society. He proved his theory about treating both the skin and mind yet again by developing preparations, based upon his phormula-3 technology, that helped heal scar tissue on the face of famous Hungarian actress, Frida Gombaszögi, when she was shot in the face by a rejected suitor. One can only imagine the intimate conversations between doctor and patient as he worked to restore her physical appearance while building her confidence by treating the unseen scars. After months of consultation and largely to Dr. Laszlo’s credit, Ms. Gombaszögi made a triumphant return the stage! These early successes spurred on the young doctor to focus more on his research, which led him to open the Erno Laszlo Institute for Scientific Cosmetology, first in Budapest in 1927, then in New York in 1939. His pioneering preparations and mindful rituals that went along with them resonated with European royalty, Hollywood stars and celebrities to whom he became skin advisor and confidante—but that wasn’t what drove him. From his early days throughout his entire career, the mind and body connection, the interconnectedness of how you look and how you feel was his mission, his message. The  Birth  of  Psychocosmetology Early on, Dr. Laszlo knew that how a person felt has major implications in how they looked—and it also worked in reverse: how a person looked played a significant role in how they felt. As an undergraduate, he began “wedding medical science to cosmetics”12 to create preparations that would enhance the natural beauty of the skin. From those early days in the laboratory to the laboratories at his Institutes, Dr. Laszlo continued to formulate preparations for his patients, perfecting and refining them to provide options for clean, healthy skin for his ever-growing clientele. The tradition of Dr. Laszlo’s research continues today as new discoveries in skin care join the tried-and-true treatments that stand the test of time. Bringing skin care treatments that were revolutionary for the times, Dr. Laszlo took great pride in knowing he was improving the lives of his clients. At this point, he was treating mostly well-off and often famous women, who had the means to afford customized care at his Institute. His deep belief that all women were, or could be, beautiful with his skin wellness treatments and tailored regimens spurred him to explore how to get his preparations into the hands and onto the faces of what he called “the average woman,” whom he praised as highly and with as much respect as he did his celebrity patients. Skin  Wellness for    Everyone In 1952, Laszlo decided to make his preparations available to women and men outside of his Institute by forming partnerships with select upscale department stores. His mission was to help people everywhere feel empowered to be their best selves through a healthy skin complexion. He didn’t want to just sell products; once again, he trained his team of skincare advisers to listen to their clients. Consultants, who were specifically trained in Laszlo’s methods, carefully documented an individual’s skin conditions, then recommended the exact preparations and rituals they needed for their skin types. Each client became a member of the Erno Laszlo Institute following completion of a detailed questionnaire for an “invisible consultation.” This gave them the opportunity to get Laszlo’s expertise all over the USA without the time and expense of a trip to his Fifth Avenue Institute in New York and eventually expanded Dr. Laszlo’s reach to thousands all around the world. Completing the questionnaire was to be done at home by the client. Each questionnaire, whether for men, women or adolescents, had a unique code to protect the person’s privacy while allowing the Institute to track their product use and make the right recommendations and modifications to each ritual. In keeping with Dr. Laszlo’s holistic approach, in addition to an exhaustive list of questions about skin conditions, skin care routines and make-up use, probing questions were asked about stress levels, relationships, sleeping and eating habits, moods, medications and much more. His pioneering and unique deep enquiry is akin to the modern approach taken today by most psychodermatologists. The questionnaires were reviewed by Dr. Laszlo himself to be sure he agreed with the consultants’ observations and tailored regimes. He also reviewed periodic progress reports the consultant would complete about client’s skin and their compliance with the prescribed rituals. This strict approach to treating the skin and the rigorous process and to become an Erno Laszlo skincare consultant was confirmed by Ms. Anne McFadden, the company’s longest-serving employee. “You had to work at Saks for a full year before you could get into the highly coveted Erno Laszlo Institute training program. After that, it took another six months of education and practice before you could start consulting with clients and prescribing the line,” she recalls. Ms. McFadden, who is in her 80s and without a wrinkle on her face, is still going strong as an ambassador for the brand after more than 40 years with the company. “I have clients who have been with me all that time, from all over the world,” Anne says. When asked for the secret to her longevity, she replies simply with, “I believe in the Erno Laszlo preparations and scientific methods.” In a meeting with his new skincare consultants, Dr. Laszlo engaged them with these words: “I turn to you with confidence in our shared mission: bringing beauty and happiness to thousands of people through the science of cosmetology. Yes, I said science, for it has always been my greatest belief, a belief which I put into practice, that chemistry, medicine and psychology—all must be brought into play in the study and development of cosmetics.”13 Science of Skin and Mind Dr. Laszlo had an unwavering focus on the science behind the formulations and a deep insight into human behavior. The rooms of his Institutes were calming in décor and decorum. Consultations were private, personal and fully documented. He listened to his patients and his abiding respect for his clientele, mostly women, was evident in the way he talked to them and about them. He understood them when hemarveled, “Beauty is both physical and psychological. A beautiful skin, for example, can be a woman’s greatest psychological asset.  An unsightly one can reflect misery mentally and handicap a woman’s whole personality.”14  Taken all together—the interconnectedness of dermatologic science plus the preparations and rituals to beautify the skin plus the emotional wellbeing component—it can be confidently stated that Dr. Erno Laszlo is the father of ‘psycho-cosmetology,’ a phrase he coined early in his career. His insights and ongoing research paved the way for today’s focus on the benefits to patients that can be expected when the mind and skin are understood and treated holistically through the modern practice of psychodermatology. The  Laszlo  Method His approach was revolutionary for its time and stands the test of time, as well. Let’s see how. Of his science-based preparations, Dr. Laszlo said, “Ours is honest magic without trickery.”15 Let’s start with the basics: cleanliness. The facial cleansing method of choice in the 1940s and ‘50s was to use cold cream to remove makeup and moisturize the skin. Dr. Laszlo was aghast that women were leaving dirt and oils on their faces. In an article in the April 3, 1952, Atlanta Journal, he told columnist Lois Norvell, “Water is a daily necessity for every skin. People take baths every day, wash their hands 20 times a day. How is it possible that they say, ‘from the chin down, water; from the chin up, no water’? Water can give you a lift to skin beauty quicker than any cosmetic. If water did not exist, as a cosmetologist, I would have to invent it.”16 Maintaining clean and well hydrated skin is a cornerstone of the Erno Laszlo healthy skin ritual and promoted by all dermatologists today.  Next, Dr. Laszlo was a pioneer in the early science and understanding of the acid mantle17 on the skin (dubbed the “acid cloak” by Dr. Laszlo). The acid mantle is a thin film on the surface of the skin that acts as a barricade against bacteria and keeps moisture in. Its slightly acidic pH makes it the skin’s first line of defense against the elements.18 Essential fatty acids are components of a healthy acid cloak. Dr. Laszlo explained in a discussion at his NY Institute in September 1952: “Without these fatty acids, our skin would be a breeding ground for millions of bacteria. The appearance of aging skin is caused by fatty acid deficiency and an excess alkaline condition.” He called the discovery of the skin’s acid cloak formed by fatty acids one of the greatest advances in modern dermatology. He theorized that most complexion issues that were not from systemic causes could be avoided with a healthy essential fatty acid protective cloak. Working tirelessly on formulations using fatty acids, he developed a “unique substance entirely new to the science of cosmetics with a pH almost identical to the normal pH of skin.”19 He called it pHelityl.  Read how Philadelphia Inquirer reporter Cynthia Cabot described it in her April 2, 1952, article: “Revolution is a mild term for the beliefs and theories on which Dr. Laszlo has established his treatments. He has polished up a contradictory term called “fatty acids” to describe the X-quotient every skin should have to stay beautiful. The number 17,776 might sound like a telephone figure to you, but actually, it is the lucky number for thousands of women who have ‘discovered’ the discoveries of Dr. Laszlo. After experimenting for years with formulas and ideas, he finally settled on the results held by test tube number 17,776, the ‘fatty acid’ complex he has called pHelityl.” Medical Skin Wellness Dr. Laszlo often noted his mentor Joseph’s view that “only a doctor trained and experienced in all branches of medical science can be a good dermatologist.”20 Through his training as a dermatologist, his keen interest in people and his attentive listening, Laszlo brought the best of medical science to the practice of cosmetic dermatology. Because patients would use his preparations over the unappetizing concoctions from an older era, Dr. Laszlo noted that “this is where [cosmetic dermatology] comes to the rescue of dermatology.”21 He was interested in the health of the entire body, so his prescribed routines and regimens were not confined to skin care. Dr. Laszlo recommended healthy eating over, drinking plenty of water, exercising, avoiding sun overexposure, and paying attention to mental wellbeing. Reviews of current skin care literature bear out the theories Dr. Laszlo pioneered or championed: pH balance, essential fatty acids and a healthy acid mantle are still the route to a healthy, vibrant complexion. From an overall health viewpoint, current medical and mental health advice from physicians and psychologists concur with Dr. Laszlo’s recommendations from the last century. His cutting-edge insights and methods in his time are still relevant in ours. Self-care:  What’s Love  Got  To  Do  With  It? While physicians are acknowledging the holistic care of skin and the mind in the practice of psychodermatology, the public has swiftly embraced the concept of self-care. Self-care is defined as taking steps to look after your physical and emotional health. The goal is wellness, coping with daily stressors and being the best one can be. Certainly, accelerated by the global pandemic, interest in self-care is on the rise. Google Trends reports web searches for the term have more than doubled since 2015.22 It’s not about being indulgent or selfish; it’s about loving yourself enough to be aware of how you feel and to focus on your wellbeing so you can do your daily tasks, including caring for others. Throughout his career, Dr. Laszlo counseled his patients in the art and importance of self-care, way before it became a “thing.” He expected his patients to rigorously follow his instructions, which included at least twice daily care of the skin in a specialized ritual of cleansing, splashing, moisturizing. He was known for dropping patients who didn’t take his counsel seriously. In what now seems like enforced self-care, Laszlo knew that a healthy, daily skin care routine had benefits well beyond a clean face. It provided his patients, mostly women, with time to themselves, a moment to pause, to think and regroup. Modern dermatologists note that any act of skin care can be considered self-care, which can be an important step to improving mental health. “By having a set routine, one knows what to expect, and this is a relief,” dermatologist Marie Jihn said. “The more a routine it becomes, the less stress it becomes. In the process, you also look better.”22 Read what NY Mirror columnist Alma Archer said about Dr. Laszlo’s approach over 80 years ago in a June 11, 1940, article: “The first tenet of the Laszlo credo of beauty is that it comes from within. Although the face and scalp treatments include the application of creams… and individual preparations for home care, immense stress is laid on the inner condition of the woman’s body. Even her psychology is explored to discover whether her beauty troubles are chronic or the temporary result of emotional or mental strain.”23 Talk about self-care! Beauty in One’s Own Mind  Dr. Laszlo was prolific in attestations about his view of women. Recounting with pride that he worked with and for women his entire career, he often noted his admiration because “women have achieved a miracle in the face of overwhelming odds – men!”2  While he is famous for being the skin care counselor for the likes of Greta Garbo, Audrey Hepburn, Marilyn Monroe and Jacqueline Kennedy Onassis, he was enamored of all women and assured them they could get the same results as these famous ladies by strictly following his skin care instructions.  He maintained that beauty was ageless and shone from within stating that “A young girl can be pretty. It takes maturity to attain beauty. It is a question of nuance.”25 When accepting an award for his work, he likened his preparations to inventions of Edison, Bell, and the Wright Brothers, noting, “It is not my own importance that I wish to stress, but the importance of a woman’s face. A face represents not only beauty but all the qualities of the heart, soul and brain.”26 Dr. Laszlo spent his entire career changing the perceptions of his clients, moving them away from unconscious acts of self-absorption to a nuanced and deliberate process of self-actualization. Laszlo recognized that women should pursue beauty for themselves, a rather revolutionary perspective when he provided this viewpoint during an interview on January 31, 1940, with columnist Charles Estcourt, Jr.: “When a woman wants to be beautiful for her own sake, then she is happy. When she wants to be beautiful for the sake of someone else, she is not happy and is heading for greater unhappiness.”27 Actress and humanitarian Audrey Hepburn famously said, “I owe 50% of my beauty to my mother and the other 50% to Erno Laszlo.” This icon of beauty, poise and grace also said, “I believe that happy girls are the prettiest girls.” Erno Laszlo concurred when he said in 1951, “The most miraculous of all beautifiers is happiness.”28 References  Institute Package_SKM_C30821070212490 Concepts in Psychodermatology: An Overview for Primary Care Providers, 2020, https://doi.org/10.1016/j. 2020.04.015 Association for Psychoneurocutaneous Medicine of North America (APMNA); http://www.psychodermatology. us/page-1823653 European Society for Dermatology and Psychiatry (ESDaP); https://www.psychodermatology.net/page1. aspx?p=13&t=1 New York City Mirror, June 11, Laszlo Archive IIA46m.tif https://www.medicaljournals.se/acta/content_files/files/pdf/96/217/EditorialSuppl217.pdf https://oxfordmedicine.com/view/10.1093/med/9780199568741.001.0001/med-9780199568741-chapter-262 Marshall C., Taylor R., Bewley A. Psychodermatology in clinical practice: main principles. Acta Derm Venereol 2016; Suppl 217: 30-34. Jewell , The Angel of Beauty. 1998. Erno Laszlo LLC, p.14. 1951 Speech to Fashion Laszlo Archives, p.3 Employee Laszlo Archives The Story of Erno Laszlo. Laszlo Archives Employee Laszlo Archives, p.2 1951 Speech to Fashion Laszlo Archives, p.2 Honesty without trickery Atlanta Journal, Date Surber C., et al. The acid mantle: a myth or an essential part of skin health. Curr Probl Dermatol . 2018;54:1-10. Epub 2018 Aug ; DOI: 10.1159/000489512 Understanding your skin’s acid mantle and why it’s so Good Housekeeping Institute. Oct. 15, 2020. https://www.goodhousekeeping.com/beauty/anti-aging/a32497176/what-is-acid-mantle/ Address from Laszlo at the Erno Laszlo Institute, NY, Sept. 9, 1952 Laszlo manuscript 1965, p. 23 Lawler M, Laube What Is Self-Care and Why Is It So Important for Your Health? https://www.everydayhealth. com/self-care/ Rearick When Skin Care Is Also Self-Care. HuffPost, Feb. 26, 2018. https://www.huffpost.com/entry/skin- care-is-self-care_n_5a86e975e4b00bc49f4341dc NY Mirror columnist Alma Archer said about Laszlo’s approach 81 years ago in a June 11, 1940 1951 Speech to Fashion Laszlo Archives Philadelphia Inquirer reporter Cynthia Cabot described it in her April 2, 1952 Award Speech, Laszlo Archives January 31, 1940 interview with columnist Charles Estcourt, Jr 1951 Speech to Fashion Group. Laszlo Archives

Content for this white paper was derived from an advisory board meeting of experts in the mind-skin connection as well as from the literature. This white paper was supported by Erno Laszlo, Inc. Advisory Board Participants and Affiliations Cherie Ditre MD (University of Pennsylvania), Richard Fried MD, PhD (Private Practice), Marsha Gordon MD (Mount Sinai), John Koo, MD (University of California San Francisco), Ladan Mostaghini MD (University of Wisconsin), Even Rieder MD (NYU Grossman School of Medicine), Mary L. Stevenson (NYU Grossman School of Medicine), Richard Wortzel (University of Pennsylvania) Introduction The skin is an architectural marvel, designed by evolution to be both protective and resilient. Pliable yet tough, the skin combats environmental insults through a program of continuous self-renewal that maintains its function. However, like all other organs of the human body, the skin is susceptible to both intrinsic and extrinsic factors that, over time, cause not only skin conditions, but also the visible and invisible signs of aging. The steady deterioration of the dermal and epidermal layers of the skin with age is caused by a combination of factors including reduced cellular proliferation and collagen synthesis, extracellular matrix remodeling, and changes in epidermal morphology (Crane 2015). The skin protects the body’s contents through a series of chemical, mechanical, and biologic barriers. The chemical barriers of the skin include antimicrobial substances and melanin. The skin is host to abundant bacterial populations, the composition of which is modulated substances secreted by the skin. The low pH of the skin—referred to as the acid mantle—inhibits the proliferation of bacteria. At the same time, dermicidin and antibacterial substances in sebum kill bacteria directly, and skin cells also secrete natural antibiotics, the defensins, that perforate and kill bacteria. Wounded skin releases cathelicidins—a protective antibacterial peptide that helps prevent infection by group A streptococcus bacteria. The physical barrier of the skin largely arises from the structure of the stratum corneum, which consists of multiple layers of dead, flattened cells and glycolipids that together defend against mechanical insults and work with the acid mantle and other substances secreted by the skin to ward off bacterial invasion. Finally, the skin acts as a biologic barrier by hosting elements of the immune system. Skin-resident dendritic cells act as a first line of defense, ingesting foreign substances, processing them, and presenting them to lymphocytes to activate the immune system. Dermal macrophages dispose of viruses and bacteria that penetrate the chemical and physical barriers of the skin and also act as antigen presenters (Marieb 2019). Stress is formally defined as a state of threatened homeostasis provoked by a psychological, environmental, or physiologic stressor. While stress has considerable value in adapting to disturbances, in modern life it can be maladaptive, as shown by the fact that stress has been directly linked to risk for a broad range of diseases, including cardiovascular disease, metabolic disease, various psychiatric and neurodegenerative disorders, and cancer (Cohen 2007). Stress can be considered both an intrinsic and extrinsic factor that influences skin aging. Increasing evidence suggests there is a 2-way relationship between stress and skin quality, with direct impacts on keratinocyte and fibroblast number and function as well as on the composition of the extracellular matrix. It is also clear that psychological stressors lead to aberrant barrier function, with decreased epidermal lipid and structural protein synthesis, decreased hydration of the stratum corneum, and increased transepidermal water loss (Maarouf 2019), and can also result in immune system dysfunction leading to systemic and local inflammation (Liu 2017). Together, these factors interact to generate the visible and invisible signs of aging, make the skin more susceptible to environmental insult, and lower the threshold at which skin diseases manifest.   This white paper will not consider patients with skin diseases associated with a primary psychiatric disorder. These disorders, such as delusional infestation, somatic symptom disorders, and body dysmorphic disorder, are best managed in the setting of a mental health practice. Instead, here we will focus on the interaction between stressors and skin health. Lessons will be derived from what is known about the interaction between stress and psychological health in both healthy individuals and people with common dermatologic diseases, such as acne, psoriasis, rosacea, and atopic dermatitis. Finally, this white paper will examine the interaction between the dermatologist and the patient and the benefits for both in managing not only the skin but also the mind-skin connection. The Link Between Skin Quality and Stress It is well-established that stress exacerbates disease severity in patients with dermatologic diseases. For example, among patients with acne—the single most common skin condition seen by dermatologists—it is clear there is a strong relationship between stress and severity (Chiu 2003).  After adjustment for change in sleep hours, perceived sleep quality, and perceived diet quality, increases in stress strongly correlated with a progressive increase in acne severity (r=0.61; P<0.01). Of note, stress experienced during an academic exam correlated with perceived acne severity, with patients who experienced intra-exam stress reporting a Leeds Acne Score that was approximately 30% higher than that reported during nonexamination periods (P<0.01). The relationship between stress and acne was further confirmed in a cross-sectional study conducted among 144 female medical students identified a strong relationship between stress severity and acne grade (P<0.01 for trend) (Figure 1) (Zari 2017). Similarly, stress ratings were directly associated with symptom severity in patients with rosacea or atopic dermatitis (Drummond 2017). Figure 1. Relationship between stress severity and acne grade among female medical students (N=144). Acne grades ranged from 0 (no acne) to 3 (severe acne). Error bars: ±1.00 standard error (Zari 2017) The connection between stressors and skin is perhaps best established in people with psoriasis, in whom stress has been associated with disease onset, flare-ups, and psychological distress. There is a 2-way interaction between stress and disease severity in many patients, as the perceived disfigurement and stigmatization of the disease results to anxiety, leading to a vicious cycle of increased stress and exacerbations in disease manifestations (Tampa 2018). In fact, more than two-thirds of patients with psoriasis report that stressful events have a direct association with disease flare (Xhaja 2014). This link between stress and skin quality also exists in the general population who have not been diagnosed with underlying dermatologic conditions. For example, a study conducted in 529 medical students—who are at significant risk for severe stress—divided the study population into 3 groups: least stressed, moderately stressed, and highly stressed, based on the results of the validated Perceived Stress Questionnaire (PSQ) (Bin Saif 2018). Skin issues were measured using a self-reported skin complaints questionnaire. In this study, as compared with the least-stressed students, highly stressed students suffered from significantly more oily, waxy patches or flakes on the scalp, dry/sore rashes, warts, pimples, itchy skin, itchy hands, hair loss, scaly skin, troublesome sweating, and other rashes on the face (all P ≤ 0.05). The odds ratios for these conditions ranged from 1.94 for nail biting to nearly 5 for face rashes. Mediators of The Mind-Skin Connection Stress alters a number of pathways that can contribute to skin quality. Embryologically, the nervous system and the skin are derived from the same origin tissue: the ectoderm. As such, the brain and skin have some overlapping capabilities—for example, the skin has its own equivalent of the hypothalamic-pituitary-adrenal (HPA) axis, which may coordinate with the central HPA axis in the stress response. Table 1 summarizes the major stress mediators in the skin, their sources, effector cells, and functions in skin. Each will be discussed in greater detail in this section. Table 1. Major stress mediators in the skin. Adapted from Chen 2014 and references in the body of this white paper. Stress Mediator Sources Skin Functions Corticotropin releasing hormone (CRH) ·Hypothalamus ·Skin keratinocytes ·Sebacytes ·Mast cells ·Stimulation of ACTH and cortisol production ·Proliferation, differentiation, apoptosis, inflammation, and angiogenesis Adrenocorticotropin (ACTH) ·Pituitary gland ·Skin melanocytes, epidermal and hair ·Follicle keratinocytes and dermal fibroblasts ·Langerhans cells and macrophages ·Stimulation of cortisol and corticosterone production ·Melanogenesis ·Cytokine production ·Cell proliferation ·Hair growth ·Immune regulation Cortisol · Adrenal cortex ·Skin hair follicles, melanocytes, and fibroblasts ·Slows proliferation of epidermal keratinocytes ·Stimulates proliferation of fibroblasts and melanocytes ·Induces degranulation of mast cells ·Increases vascular permeability ·Induces expression of pro-inflammatory cytokines ·Compromises epithelial barrier function Neurotrophins ·Central nervous system ·Skin sympathetic neurons ·Mast cells ·T and B cells ·Keratinocytes, fibroblasts, and melanocytes ·Promote survival and differentiation of mast cells ·Modify inflammatory cytokines expression ·Promote proliferation of keratinocytes ·Important for melanocytes migration, viability, and differentiation ·Protect from oxidative stress and apoptosis ·Promote fibroblast differentiation and migration Substance P ·Sensory nerve fibers ·Induces inflammation by promoting cytokine release ·Activates mast cells ·Induces lymphocyte proliferation ·Induces vascular permeability ·May modulate the skin microbiota Prolactin ·Pituitary gland ·Skin hair follicle and epidermal keratinocytes, fibroblasts ·Adipocytes ·Sweat glands ·Sebaceous glands ·Stimulates keratinocyte proliferation and keratin production ·Stimulates sebum production in sebaceous glands ·May have an immunomodulatory role Catecholamines (epinephrine and norepinephrine) ·Adrenal medulla ·Skin nerve fibers ·Keratinocytes ·Regulate keratinocytes proliferation, differentiation, and migration ·Promote melanogenesis in melanocytes ·Decrease fibroblasts migration and collagen secretion ·Decrease wound healing The Central and Skin HPA Axis The effect of stress on the skin is primarily mediated through the HPA axis. The sensation of stress is associated with the release of corticotropin-releasing hormone (CRH), which binds to its receptor on the pituitary gland and stimulates secretion of adrenocorticotropin (ACTH). ACTH, in turn, binds to receptors in the adrenal cortex, stimulating the production of glucocorticoids (GC) such as cortisol and corticosterone (Figure 2) (Marieb 2019). Cortisol is the primary stress hormone in the human body. After binding to its receptor, a complex cascade of events results in changes in gene expression. Cortisol levels, under non-stressed conditions, naturally oscillate daily, with peak levels in the early morning and a nadir at around midnight. Stress can disrupt both the pattern and amount of cortisol produced, which can result in a relatively immunosuppressed state (Chen 2014). Figure 2. A simplified representation of the HPA   The skin itself has its own “HPA system” in that CRH and ACTH are produced by skin cells, which also express the cognate receptors for these molecules. In the skin, CRH is produced by keratinocytes, melanocytes, and mast cells in the presence of stressors such as immune cytokines, UV light, and cutaneous disease states. CRH has diverse effects in the skin, including slowing the proliferation of epidermal keratinocytes and stimulating proliferation of fibroblasts and melanocytes. CRH also induces degranulation of skin-resident mast cells, increases vascular permeability, and induces the production of the proinflammatory cytokine interleukin (IL)-6. ACTH stimulates production of IL-18, another pro-inflammatory cytokine (Chen 2014). Skin barrier dysfunction is tightly associated with eczema, rosacea, psoriasis, acne, and other cutaneous diseases. However, variability in its health also contributes to skin quality in otherwise healthy patients.  Much of the mind-skin connection is attributable to the overproduction of cortisol and its effect on the skin barrier. Increased cortisol production has been shown to slow the production of beneficial oils, resulting in dry, rough, irritated skin and accelerated transepidermal water loss. At the same time, cortisol stimulates the overproduction of sebum, increasing the likelihood and severity of acne. These changes also alter the pH of the skin, compromising the acid mantle and inducing changes in the composition of the skin’s commensal microbiota (Altemus 2001). In a study that recruited 27 medical students without a dermatologic disease, levels of 11β-hydroxysteroid dehydrogenase 1, the enzyme that converts cortisone (the inactive form of cortisol) to cortisol, were measured and correlated with skin barrier function. In this study, elevated expression of 11β-hydroxysteroid dehydrogenase 1 in oral mucosa (which correlated closely with expression in epidermal keratinocytes) was associated with increased cortisol in the stratum corneum and deteriorated skin barrier function, as measured by decreased expression of keratinocyte differentiation markers. The Skin and the SAM Axis Stress is also associated with the release of catecholamines, such as epinephrine and norepinephrine, by modulating the activity of the sympathetic-adrenal medullary (SAM) axis (Chen 2014). These catecholamines are critical elements of the stress response and are involved in the fight-or-flight response to perceived danger. They have a broad range of well-understood effects, including heart rate and respiratory acceleration, vasoconstriction outside of muscles, and increased perspiration. In the epidermis, these signaling molecules downregulate keratinocyte proliferation, differentiation, and migration and increase melanogenesis in melanocytes. In the dermis, chronic epinephrine signaling appears to reduce fibroblast migration and collagen deposition—delaying wound healing—and also induces the expression of IL-6 (Romana-Souza 2011; Romana-Souza 2010). Signaling from these molecules has a less well-appreciated role in regulating the immune response; for example, data suggest that norepinephrine modulates human dendritic cell activation by altering cytokine release (Goyarts 2008). Other Physiologically Active Stress Mediators While the peripheral nervous system and the immune system are often considered wholly separate, abundant data suggest an intimate and bidirectional relationship (Chiu 2013). Both intrinsic factors—such as other stress mediators and inflammatory molecules—and extrinsic factors, such as noxious stimuli and microbial invasion, are detected by the peripheral nervous system, which responds via a number of secreted factors such as neuropeptides and neurotrophins. These factors amplify the local stress response and activate neurogenic inflammation (Chiu 2013). Nerve growth factor, a member of the neurotrophin family, binds to cell-surface tyrosine kinase receptors expressed on mast cells, immune cells, keratinocytes, fibroblasts, and melanocytes (Chen 2014). Nerve growth factor is also secreted by immune cells and can act directly on peripheral sensory neurons to cause sensitization (Chiu 2013). Sensitization of nociceptors, in turn, results in increased release of neuropeptides that enhance immune cell activation, resulting in a positive feedback loop that drives the inflammatory response (Chen 2014). Substance P, a member of the tachykinin neuropeptide family, is a stress-related neurotransmitter and neuromodulator that binds to receptors present on a broad range of cell types, including blood vessel endothelial cells, immune cells, fibroblasts, and neurons. Stress is associated with a significant increase in substance P-positive nerve fibers (Chen 2014). It has long been recognized as a modulator of pain perception, but it also plays roles in gastrointestinal function, memory, angiogenesis, vasodilation, and cell growth and proliferation (Graefe 2021). In the skin, substance P has been shown to play a role in initiating and enhancing the inflammatory response by stimulating cytokine release, activate mast cells, and induce lymphocyte permeability (Chen 2014). Is There a Mind-Skin Microbiota Connection? While the importance of the microbiota in gastrointestinal function is widely appreciated, the skin is also the home for a rich community of commensal and potentially pathogenic microorganisms, including bacteria, fungi, and viruses (Byrd 2018). Many of the normal microbial residents of the skin actively defend the body’s envelope by producing molecules that inhibit colonization of other microorganisms or alter their behavior. In healthy adults, the skin microbiota remains stable over time; however, increasing evidence suggests that stress can have a dramatic effect on the composition and behavior of these organisms. For example, glucocorticoids, which—as discussed above—are critical mediators of the stress response, have been shown to have a direct impact on the release of antimicrobial peptides by the skin (Holmes 2015). In addition to its direct roles in neuroinflammation, substance P also appears to provide a link between stress and the microbial flora of the skin (Mijouin 2013). It is released in sweat during stress and has both direct and indirect antimicrobial activity by acting as an antimicrobial peptide and stimulating the release of cathelicidins and defensins. However, certain bacteria, such as Bacillus cereus—a common transient resident of the skin—can detect and respond to substance P in a manner that increases virulence. In the case of B cereus, substance P induces the release of superoxide dismutase, an enzyme that protects the bacteria against oxidative stress, increases bacterial production of collagenase, and stimulates the formation of protective biofilms (Mijouin 2013). Similarly, both Staphylococcus aureus and Staphylococcus epidermidis respond to the presence of substance P with a marked increase in cytotoxicity (Mijouin 2013). Data also suggest that cortisol significantly increases the inflammatory response to Propionibacterium acnes, the bacterium associated with the pathogenesis of acne and several other opportunistic infections (Holmes 2015). What is the Impact of Stress on Inflammation? The balance between pro- and anti-inflammatory factors is altered by stress. The net effect of stress on inflammatory mediators changes with the chronicity of exposure to stress. Acute stress is associated with an adaptive response that enhances immune response, whereas chronic stress often results in immunosuppression. Intense stress may overactivate the immune system, resulting in the release of a variety of pro-inflammatory mediators including C-reactive protein, IL-6, TNFα, IL-1β, and activate the transcription factor nuclear factor kappa B (NF-κB), which is known to play a role in modulating the expression of pro-inflammatory products (Liu 2017). The effects of stress are mediated, in part, by glucocorticoids released by the adrenal glands during the stress response (discussed above). Glucocorticoids have a range of effects on the immune system that depending on the duration of release, have anti- or pro-inflammatory effects. As noted above, stress is a clear trigger for many inflammatory diseases of the skin, such as psoriasis, thus providing a direct clinical link between stress, inflammation, and symptoms. What is the Impact of Stress on Skin Aging? The data summarized above suggest the presence of a direct mind-skin connection and that stress has potentially detrimental effects that are mediated by multiple intimately interconnected pathways. It is also well understood and readily apparent that chronic stress is a major contributor to the appearance of aged skin; this connection may be mediated both through the neuroendocrine and immune systems (Dunn 2013; Liu 2017). Telomere shortening, leading to premature replicative senescence of skin cells, may also provide a link between stress and skin aging, although the precise underlying mechanisms are not yet fully elucidated (Chen 2014). Continuous, low-grade inflammation—such as that induced by chronic stress—may cause gradual tissue damage that, while present systemically, manifests visibly in skin aging (Zhuang 2014). This has been referred to by some authors as “inflammaging.” The effects of inflammation on the skin can be modeled through experimental exposure of skin to ultraviolet light, which induces epidermal keratinocytes to release inflammatory cytokines, induces mast cells to generate prostaglandins and other inflammatory mediators, and results in the massive infiltration of neutrophils into the epidermis and dermis, where they play roles in clearing apoptotic cells. However, these cells also indiscriminately release a number of degradative enzymes, such as neutrophil elastase and various matrix metalloproteinases, that degrade the extracellular matrix. The complement system is also induced under conditions of stress and can recruit and activate dermal macrophages. Table 2 summarizes the role of inflammatory factors known to have a role in skin aging. Table 2. Known key inflammatory factors and their role in skin aging (Zhuang 2014) Proinflammatory Factors Pathway and Potential Skin Damage Reactive oxygen species Cause skin cell damage; generate oxidized lipids; induce MMP expression in dermal fibroblasts TNFα, IL-1 Initiate inflammatory responses in skin and induce synthesis and release of other pro-inflammatory cytokines IL-6, IL-8, etc Recruit neutrophils and macrophages; activate dermal fibroblasts to secrete MMPs Neutrophils Produce elastase and MMPs that cause ECM degradation MMPs Cause ECM degradation, damage dermal connective tissue and cause visible skin aging Complement system Activates macrophages; induced particularly by UV radiation Macrophages Infiltrate skin after UV exposure; generate ROS and MMPs that cause ECM degradation ECM = extracellular matrix; IL = interleukin; MMP = matrix metalloproteinase; ROS = reactive oxygen species; TNF = tumor necrosis factor; UV = ultraviolet. Of note, poor sleep quality—which is intimately connected to stress—is likely to contribute to skin aging. The skin of individuals who suffer from poor quality sleep is marked by relatively reduced elasticity, fine lines, uneven pigmentation, and slow recovery from skin barrier disruption (Oyetakin-White 2013). Stressors such as smoking and air pollution are both considered contributors to premature skin aging. The effects of these environmental stressors may be mediated by an increase in reactive oxygen species (ROS) production, vitamin E depletion, lipid peroxidation, and the induction of collagen- and elastin-degrading matrix metalloproteinase expression (Chen 2014; van Doren 2015). Can Stress Reduction Interventions Improve Skin Quality? Direct Evidence for Stress Reduction and Improvements in Skin Quality The majority of evidence for a link between stress reduction and skin quality comes from studies in patients with psoriasis and atopic dermatitis. The impact of stress reduction through mindfulness meditation has been prospectively evaluated in patients with psoriasis (Kabat Zinn 1998). In this study, patients were randomly assigned to either a mindfulness meditation guided by audiotaped instructions during phototherapy or photochemotherapy, or a control condition of the light treatments alone without meditation instructions. Patients who received mindfulness meditation instruction were significantly more likely to reach 50% skin clearance (P = 0.013) and complete skin clearance (P = 0.033). Similarly, a small case-control study of relaxation therapy found profound differences in clearing among patients with psoriasis: among patients who were trained in relaxation therapy, 70% achieved Psoriasis Area Severity Index (PASI) 50 at the end of 2 months, as compared with 13.3% of the control group (Neerackal 2020). The efficacy of stress-reduction modalities have also been explored in atopic dermatitis. In one trial, patients (N=102) with atopic dermatitis were randomly allocated to 12 weeks of cognitive-behavioral therapy (CBT), delivered by internet, or a control that gave subjects about standard care; the primary outcome measure was the difference in atopic dermatitis symptoms, as measured by the Patient-Oriented Eczema Measure (Lagerlof 2021). At 12 weeks, patients who received CBT had significant, moderate to large reductions in atopic dermatitis symptoms, combined with significant reductions in itch intensity, perceived stress, sleep problems, and depression. Of note, these gains were maintained through 12 months. A second study found that psychological interventions in patients with atopic dermatitis were associated with significantly larger improvements in skin conditions than standard medical care and were associated with significant reductions in the need for topical steroid treatment (Ehlers 1995). Aerobic exercise has broad, systemic benefits in the human body, including reduction of stress, and data suggest that these benefits can also be extended to the skin. For example, in one recent study conducted in humans, short-term aerobic exercise was associated with reduced signs of skin aging, including a reduction in stratum corneum thickness (which generally increases in thickness with age), increased stratum spinosum thickness in elderly subjects, and increased reticular dermis content. These effects may be mediated by increases in circulating IL-15, an exercise-induced hormone that has previously been associated with reduced adiposity, increased muscle mass, improved mitochondrial function and exercise capacity (Crane 2015). Finally, limited data suggest that aromatherapy may have some benefit (with the caution that the aerosolized oils may exacerbate skin conditions in sensitive individuals). In one study, aromatherapy was associated with a reduction in stress-induced serum and salivary cortisol and enhanced skin barrier recovery, as measured by transepidermal water loss, in both animal models and humans (Fukuda 2012). Other Stress-Reduction Modalities Mindfulness is a popular meditation technique that consists of 2 parts: attention and acceptance. Attention involves “tuning in” to experiences to focus on what is happening in the present moment, while acceptance involves observing those feelings and sensations without judgment (American Psychiatric Association 2021). One case-control study and one randomized clinical trial with reasonable methodologic quality showed that meditation was associated with increased telomere length; this effect was significant in female meditators (Desanayaka 2021). The effect of meditation on stress markers, such as cortisol, has been better studied. For example, in one meta-analysis of 10 studies using blood samples, meditation interventions had a moderate, albeit statistically significant, effect on cortisol levels. This effect was primarily seen in subjects with existing somatic illnesses, such as type 2 diabetes mellitus (Koncz 2021). A number of additional stress-reduction modalities may be viable candidates to consider for improving overall stress. Yoga, as it is practiced widely worldwide, has been shown to impact both the neuroendocrine and immune systems. In 1 meta-analysis of 15 relatively high-quality studies, yoga was shown to reduce inflammatory markers, including IL-6, C-reactive protein, and tumor necrosis factor, with a distinct dose-response relationship (Djalilova 2019). Yoga has also been shown to be associated with reliable reductions in serum cortisol, the primary stress hormone in the human body (Katuri 2016; Cahn 2017). In 1 reasonably well-conducted study in 121 healthy individuals, guided relaxation was associated with improved skin barrier recovery following induction of mild skin damage by tape stripping (Robinson 2015). Similarly, some evidence suggests that rituals may have a potentially anxiolytic effect by reducing cognitive load (Karl 2018). Conclusions Dermatologists have long accepted the role of stress in skin health, as it is readily apparent in the clinic in otherwise healthy individuals. Abundant evidence exists that stress and skin function and quality are intimately linked, and some evidence suggests that interventions to reduce stress, such as mindfulness meditation, cognitive-behavioral therapy, yoga, exercise, and even aromatherapy may have a positive impact on skin quality. Rituals, such as taking time with the daily application of cosmetic products, also may have the side benefit of decreasing psychological stress responses. There is an underappreciated opportunity in the dermatology clinic to improve outcomes and increase patient satisfaction with their overall treatment plan by providing guidance on stress management through non-medical interventions. From a practical perspective, the dermatologist’s time to address the sometimes complex factors underlying stress is limited; thus, there may be a role for partnerships with outside services that specialize in helping patients manage stress.Additional Reading For those with a particular interest in the mind-skin connection, we recommend the following reviews. Chen Y, Lyga J. Brain-skin connection: Stress, inflammation, and skin aging. Inflamm Allergy—Drug Targets. 2014;13:177-190. Chiu A, Chon SQY, Kimball AB. The response of skin disease to stress. Arch Dermatol. 2003;139:897-900. Holmes CJ, Plichta JK, Gamelli R et al. Dynamic role of host stress responses in modulating the cutaneous microbiome: implications for wound healing and infection. 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