The association between weight-adjusted-waist index and psoriasis: A cross-sectional study.

INTRODUCTION: This study explored the association between psoriasis and the weight-adjusted waist index (WWI), a newly developed measure of adiposity. The research was conducted among adults in the United States. METHODS: Utilizing survey data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2009 to 2014, the present study aimed to investigate the potential correlation between psoriasis and WWI within a sample of 15,920 adult participants. Employing multivariable logistic regression and nonlinear curve fitting techniques, we analyzed this plausible association. Additionally, a subgroup analysis was conducted to ascertain the consistency across diverse populations. RESULTS: A significant positive association was discovered between psoriasis and WWI in the investigated sample of 15,920 adults. After conducting a comprehensive adjustment of the model, it was observed that each incremental unit of WWI was significantly associated with an 14% elevated likelihood of developing psoriasis (OR = 1.16, 95% CI 1.01-1.36). Moreover, individuals belonging to the highest quartile of WWI exhibited a 47% higher risk of psoriasis compared to those in the lowest quartile (OR = 1.44, 95% CI 1.01-2.06). This positive correlation remained consistent across various subgroups. The study also compared WWI with BMI and waist circumference, finding that WWI is a more stable metric of obesity. CONCLUSIONS: Our study suggested that in US adults, there is a positive association between WWI and psoriasis. It also indicated that WWI showed potential as a valuable index of psoriasis among the general population.

YAP prevents senescence of dermal fibroblast and inhibits melanogenesis via paracrine effect of DKK1.

Senile skin hyperpigmentation displays remarkable histopathological features of dermal aging. The crosstalk between melanocytes and dermal fibroblasts plays crucial roles in aging-related pigmentation. While senescent fibroblasts can upregulate pro-melanogenic factors, the role of anti-melanogenic factors, such as dickkopf1 (DKK1), and the upstream regulatory mechanism during aging remain obscure. This study investigated the roles of yes-associated protein (YAP) and DKK1 in the regulation of dermal fibroblast senescence and melanogenesis. Our findings demonstrated decreased YAP activity and DKK1 levels in intrinsic and extrinsic senescent fibroblasts. YAP depletion induced fibroblast senescence and downregulated the expression and secretion of DKK1, whereas YAP overexpression partially reversed the effect. The transcriptional regulation of DKK1 by YAP was supported by dual-luciferase reporter and chromatin immunoprecipitation assays. Moreover, YAP depletion in fibroblasts upregulated Wnt/ß-catenin in melanocytes and stimulated melanogenesis, which was partially rescued by the re-supplementation of DKK1. Conversely, overexpression of YAP in senescent fibroblasts decreased Wnt/ß-catenin levels in melanocytes and inhibited melanogenesis. Additionally, reduced levels of YAP and DKK1 were verified in the dermis of solar lentigines. These findings suggest that, during skin aging, epidermal pigmentation may be influenced by YAP in the dermal microenvironment via the paracrine effect of DKK1.

The cross-linking between DNA damage, oxidative stress and epidermal barrier in keratinocytes after exposure to particulate matters and carbon black.

As the largest organ, the skin provides the first line of defence against environmental pollutants. Different pollutants have varied damage to the skin due to their own physical-chemical properties. A previous epidemiological study by our team revealed that eczema was positively correlated with different air pollutants. However, the mechanism of action from different pollutants on the skin is less known. In this work, the differences among the genotoxicity, intracellular reactive oxygen species, and barrier-related parameters caused by two kinds of air pollutants, that is, S1650b and carbon black (CB) were investigated by Western blot, TUNEL, comet assay and RNA-sequences. The results indicated that both S1650b and CB caused DNA damage of keratinocytes. With the content of lipophilic polycyclic aromatic hydrocarbons (PAH), S1650b leaked into the keratinocytes easily, which activated the aromatic hydrocarbon receptor (AhR) in keratinocytes, leading to worse damage to barrier-related proteins than CB. And CB-induced higher intracellular ROS than S1650b due to the smaller size which make it enter the keratinocytes easier. RNA-sequencing results revealed that S1650b and CB both caused DNA damage of keratinocytes, and the intervention of S1650b significantly upregulated AhR, cytochrome oxidase A1 and B1 (CYP1A1 and CYP1B1) genes, while the results showed oppositely after CB intervention. The mechanism of keratinocyte damage caused by different air particle pollutants in this study will help to expand our understanding on the air pollutant-associated skin disease at cell levels.

Skin-derived precursor conditioned medium alleviated photoaging via early activation of TGF-ß/Smad signaling pathway by thrombospondin1: In vitro and in vivo studies.

Photoaging is one major exogenous factor of skin aging. Efficacy and safety of current anti-photoaging therapies remained to be improved. Our previous studies indicated that skin-derived precursors (SKPs) alleviated photodamage by early activation of TGF-ß/Smad signaling pathway via thrombospondin1 (TSP1). However, the research concerning SKP conditioned medium (SKP-CM) has never been reported. In the current study, we aimed to explore the anti-photoaging effects of SKP-CM both in vitro and in vivo, and to elucidate the possible mechanisms. Mouse SKP-CM (mSKP-CM) collection was optimized by a comparative method. The concentration of protein and growth factors in mSKP-CM was detected using BCA protein assay kit and growth factor protein chip. The anti-photoaging effects of mSKP-CM and its regulation of key factors in the TGF-ß/Smad signaling pathway were explored using UVA + UVB photoaged mouse fibroblasts (mFBs) and nude mice dorsal skin. The research revealed that mSKP-CM contained significantly higher-concentration of protein and growth factors than mouse mesenchymal stem cell conditioned medium (mDMSC-CM). mSKP-CM alleviated mFBs photoaging by restoring cell viability and relieving senescence and death. ELISA, qRT-PCR, and western blot results implied the potential mechanisms were associated with the early activation of TGF-ß/Smad signaling pathway by TSP1. In vivo experiments demonstrated that compared with the topical intradermal mDMSC-CM injection and retinoic acid cream application, the photodamaged mice dorsal skin intradermally injected with mSKP-CM showed significantly better improvement. Consistent with the in vitro results, both western blot and immunohistochemistry results confirmed that protein expression of TSP1, smad2/3, p-smad2/3, TGF-ß1, and collagen I increased, and matrix metalloproteinases decreased. In summary, both in vitro and in vivo experiments demonstrated that mSKP-CM alleviated photoaging through an early activation of TGF-ß/Smad signaling pathway via TSP1. SKP-CM may serve as a novel and promising cell-free therapeutical approach for anti-photoaging treatment and regenerative medicine.

Serum 25 hydroxyvitamin D in non-scarring alopecia: A systematic review and meta-analysis.

INTRODUCTION: Non-scarring alopecia mainly includes androgenetic alopecia (AGA), female pattern hair loss (FPHL), alopecia areata (AA), telogen effluvium (TE), anagen effluvium (AE) and so on. Many studies had investigated the serum 25-hydroxyvitamin D level and vitamin D deficiency of patients with these diseases, but opinions varied, and no conclusion was reached. METHODS: Relevant articles were retrieved through PubMed, Web of Science, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI) and other databases. Serum 25-hydroxyvitamin D [25(OH) D] levels and vitamin D deficiency were used as our primary outcome. The odds ratio (OR) and the standardized mean difference (SMD) with 95% confidence interval were both examined for vitamin D deficiency and levels. RESULTS: Our meta-analysis had included a total of 3374 non-scarring alopecia patients and 7296 healthy controls from 23 studies through the inclusion criteria and exclusion criteria. We found non-scarring alopecia had decreased serum 25(OH)D level (WMD -7.29; 95% CI -9.21, -5.38) and increased vitamin D deficiency incidence (OR 3.11 95% CI 2.29, 4.22), compared with healthy controls. This meta-analysis chose to conduct random-effect model and subgroup analysis, because of the high heterogeneity (serum 25(OH)D level: I2 = 95%, vitamin D deficiency: I2 = 0%). CONCLUSION: Patients with non-scarring alopecia (including AA, FPHL, AGA and TE) have insufficient serum level of 25(OH)D and increased incidence of vitamin D deficiency. Vitamin D supplementation and monitoring for vitamin D deficiency may be helpful in treating non-scarring alopecia.

Survival Outcomes and Prognostic Factors of Dermatofibrosarcoma Protuberans: A Population-Based Retrospective Cohort Analysis.

BACKGROUND: Limited information is available regarding survival outcomes and risk factors of dermatofibrosarcoma protuberans (DFSP). OBJECTIVE: To investigate the clinicopathologic characteristics and survival outcomes of DFSP. MATERIALS AND METHODS: The study cohort (7,567 patients) was selected from the Surveillance, Epidemiology, and End Results Program (2000-2018). Demographic and clinicopathologic variables, survival outcomes, and prognostic factors were analyzed. RESULTS: A total of 5,640 (74.53%) and 1,927 (25.47%) tumors were located in the skin and soft tissue, respectively. The median follow-up duration was 92 months. Median follow-up times were similar between patients with lymph node (107 months) and distant (102 months) metastases; the median survival time of the 89 patients (1.18%) who died of DFSP was significantly short (41 months, p < .001). Independent risk factors for cancer-specific mortality included age at diagnosis, histologic grade, and tumor size. Patients with tumors ≥10 cm in size or histologic grade III had significantly higher DFSP-specific mortality (7.07% and 10.08%, respectively, p < .001). Tumor locations and surgical procedures did not significantly influence survival. CONCLUSION: Dermatofibrosarcoma protuberans has a favorable survival prognosis, even in patients with node-positive or distant metastases. Dermatofibrosarcoma protuberans-specific mortality is significantly higher in patients with grade III or large (≥10 cm) tumors.

Effects of donkey milk on UVB-induced skin barrier damage and melanin pigmentation: A network pharmacology and experimental validation study.

Introduction: Dairy products have long been regarded as a controversial nutrient for the skin. However, a clear demonstration of donkey milk (DM) on skincare is required. Methods: In this study, spectrum and chemical component analyses were applied to DM. Then, the effects of DM on UVB-induced skin barrier damage and melanin pigmentation were first evaluated in vitro and in vivo. Cell survival, animal models, and expression of filaggrin (FLG) were determined to confirm the effect of DM on UVB-induced skin barrier damage. Melanogenesis and tyrosinase (TYR) activity were assessed after UVB irradiation to clarify the effect of DM on whitening activities. Further, a network pharmacology method was applied to study the interaction between DM ingredients and UVB-induced skin injury. Meanwhile, an analysis of the melanogenesis molecular target network was developed and validated to predict the melanogenesis regulators in DM. Results: DM was rich in cholesterols, fatty acids, vitamins and amino acids. The results of evaluation of whitening activities in vitro and in vivo indicated that DM had a potent inhibitory effect on melanin synthesis. The results of effects of DM on UVB­induced skin barrier damage indicated that DM inhibited UVB-induced injury and restored skin barrier function via up-regulation expression of FLG (filaggrin). The pharmacological network of DM showed that DM regulated steroid biosynthesis and fatty acid metabolism in keratinocytes and 64 melanin targets which the main contributing role of DM might target melanogenesis, cell adhesion molecules (CAMs), and Tumor necrosis factor (TNF) pathway. Discussion: These results highlight the potential use of DM as a promising agent for whitening and anti-photoaging applications.

An online course about cosmetics improves skin care practices and skin health.

Background: The incidence of cosmetics-associated dermatoses is on the rise recently while the awareness and knowledge about proper utilization of cosmetics are insufficient in both the public and specialists due to limited education about cosmetics. Methods: Our aim was to build and enhance the public's ability to select appropriate cosmetics, manage possible dermatoses and improve skin-care practices and skin health by offering access to medical information via free online courses. Consequently, we launched a massive open online course (MOOC), Appreciation and Analysis of Cosmetics. An online questionnaire was also sent to evaluate the effectiveness of the course. Results: Nearly 540,000 learners were enrolled in the course since 2014. In the discussion forum, there were 8,383 posts and 73,014 replies in total, where learners were mostly concerned about topics of sun protection, cleansing and proper utilization of cosmetics in some skin diseases. 645 learners answered the questionnaire with 88.84% of the them changed skin care practices and 50.39% reported improvement in skin health. Moreover, participants who completed the course reported better understanding and utilization of cosmetics-related knowledge (p values < 0.05). 72.09% of respondents were willing to recommend this course to others. Conclusions: Free online public courses are feasible for conducting public health education campaigns related to cosmetics and associated dermatology to lower the incidence of cosmetics-associated dermatoses.

Role of mitochondria on UV-induced skin damage and molecular mechanisms of active chemical compounds targeting mitochondria.

Mitochondria are the principal place of energy metabolism and ROS production, leading to mtDNA being especially sensitive to the impacts of oxidative stress. Our review aims to elucidate and update the mechanisms of mitochondria in UV-induced skin damage. The mitochondrial deteriorative response to UV manifests morphological and functional alterations, including mitochondrial fusion and fission, mitochondrial biogenesis, mitochondrial energy metabolism and mitophagy. Additionally, we conclude the effect and molecular mechanisms of active chemical components to protect skin from UV-induced damage via mitochondrial protection which have been described in the last five years, showing prospective prospects in cosmetics as new therapeutic targets.

Self-Assembly of Cellulose Nanocrystals and Organic Colored Pigments as Reinforcement Matrix of Lipstick for Enhancing SPF.

The vermilion of the human lip, covered by a skinny epithelium with little melanin, is quite susceptible to damage from ultraviolet (UV) radiation exposure. However, commercial sunscreen filters and indelible dyes used in lipsticks can cause health hazards after percutaneous absorption or accidentally oral administration. Inspired by plant pigmentation as natural filters to protect themselves against overexposure to UV, safer bio-based sunscreens of cellulose enveloped with anthocyanin (AN) were developed using bionic design. Cellulose nanocrystals (CNC), derived from acid hydrolysis of cellulose, reinforced enhancement of UV absorption and shielding properties of AN. This innovation addresses the issue that naturally sourced UV filter application to sunscreen does not achieve a desired sun protection factor (SPF) value because of the low specific extinction value (E1,1). We also stated that the diverse formula of anthocyanin sunscreen lipsticks with CNC exhibited 10 times more SPF value than AN alone. Furthermore, they possess competitive benefits such as pleasing texture, superior adhesion, impermeable, nonphototoxicity, ease of application, and removal. This work provides a promising proof-of-concept for studying the features of natural sunscreens in the design of simple, safe, efficient, and green sunscreens.

Symmetrical Acrokeratoderma: A Case Report and Literature Review.

The current study explores a case of symmetrical acrokeratoderma, and related literature is reviewed. A 27-year-old male presented with brownish-black plaques distributed symmetrically on the dorsum of the hands and feet for 3 years, and white maceration of the lesions was observed after immersion in water. The patient was diagnosed with symmetrical acrokeratoderma, and Hirudoid ointment was topically administered twice a day for a month. The symptoms were partially alleviated, and the patient is currently under follow-up observation.

Transcriptome profiling of guinea pig skin exposed to a high-power terahertz source.

Terahertz (THz) radiation has a wide range of applications including use in medicine. However, effects of high-power THz radiation have not been clearly elucidated. We used a 2.52 THz self-made optically pumped gas THz laser, the low- and high-energy group, to irradiate the backs of Hartley guinea pigs. RNA-sequencing was done to explore global transcriptional responses in the irradiated skin. Gene Ontology analysis revealed that differentially expressed genes (DEGs) between the unexposed and low-energy exposed groups were associated with skin development, skin barrier establishment, and multicellular organismal water homeostasis or water loss regulation via the skin. On the other hand, comparison between the unexposed and high-energy exposed groups showed that the DEGs mediated monocarboxylic acid metabolism, blood vessel morphogenesis, establishment of skin barrier, blood vessel development, or angiogenesis. Our analyses demonstrate the potential effects of high-power THz source on the skin and sets the basis for further studies on the safety and application of the high-power THz in dermatology.

Facilitation of mouse skin-derived precursor growth and yield by optimizing plating density.

Multiple methodologies have been reported to facilitate skin-derived precursor (SKP) growth, but the impact of plating density on SKP growth has not been studied. To determine the optimal plating density, we used six plating densities and two types of flasks for mouse SKP (mSKP) culture. On the 14th day, the number, diameter, and viability of mSKP spheres were compared by morphological assessment and cell counting kit 8, and we found the optimal plating density was 2.5 × 105-5 × 105 cells/mL. In addition, we investigated the correlation between the SKP spheres and the adherent cell colonies in the serum-free culture system. We treated the adherent cell colonies with two culture conditions and characterized the cells generated from two conditions by immunocytochemistry and induced differentiation, respectively. The results elucidated that the adherent cell colonies differentiated into either mSKPs or dermal mesenchymal stem cells under appropriate culture conditions. In conclusion, mSKP spheres differentiated from the adherent cell colonies. The optimal plating density significantly promoted and advanced the proliferation of adherent cell colonies, which optimized mSKP growth and yield. The adherent cell colonies possessed the capacity of differentiating into different types of cells under appropriate culture conditions.

Extracellular Vesicles: Emerging Therapeutics in Cutaneous Lesions.

Extracellular vesicles (EVs), as nanoscale membranous vesicles containing DNAs, RNAs, lipids and proteins, have emerged as promising diagnostic and therapeutic agents for skin diseases. Here, we summarize the basic physiology of the skin and the biological characteristic of EVs. Further, we describe the applications of EVs in the treatment of dermatological conditions such as skin infection, inflammatory skin diseases, skin repair and rejuvenation and skin cancer. In particular, plant-derived EVs and clinical trials are discussed. In addition, challenges and perspectives related to the preclinical and clinical applications of EVs are highlighted.

Efficacy and Safety of Platelet-Rich Plasma in Melasma: A Systematic Review and Meta-Analysis.

INTRODUCTION: Melasma is a chronic and recurrent skin problem for which an effective therapy is currently lacking. Platelet-rich plasma (PRP) has recently emerged as a novel treatment for melasma, but to date there has been no systematic evaluation of its efficacy and safety. METHODS: The Web of Science, PubMed, EMBASE, China National Knowledge Infrastructure (CNKI) and the Cochrane Library databases were searched for relevant articles using the search items "melasma," "chloasma" and "platelet-rich plasma." STATA version 15.1 software was used to analyze data. Study outcomes were calculated using standardized mean differences with 95% confidence intervals (CIs). RESULTS: The database search identified ten studies involving 395 adult patients that met the inclusion criteria and were included in the meta-analysis. Analysis of pre- and post-treatment data from these studies revealed that the post-treatment modified Melasma Area and Severity Index (mMASI) score decreased by 1.18 (95% CI 0.89-1.47; p = 0.02). Subjective satisfaction evaluation of PRP treatment showed that melasma treated with the combination therapy of PRP + microneedling may have been the most efficacious treatment compared to PRP alone or in combination with intradermal injection. Adverse reactions were minor, with only a few patients reporting local congestion, temporary erythema, hyperpigmentation and discoloration. CONCLUSION: These results support the efficacy and safety of PRP used in combination or alone as treatment for melasma.

Natural compounds protect the skin from airborne particulate matter by attenuating oxidative stress.

Particulate matter (PM) is a common indirect indicator of air pollution and threatens public health upon prolonged exposure, leading to oxidative stress, increasing the risk of develop respiratory and cardiovascular, as well as several autoimmune diseases and cancer. Nowadays, as a first line defense against PM, skin health attracted much attention. Our review summarized the skin damage mechanism induced by PM, including damage skin barrier directly, reactive oxygen species (ROS) accumulation, autophagy, and two canonical signaling pathways. Furthermore, ROS and oxidative stress have been considered pathogenesis centers, with essential skin damage roles. Extracts from plants and natural compounds which present high antioxidant capacity could be used to treat or protect against air pollution-related skin damage. We conclude the extracts reported in recent studies with protective effects on PM-mediated skin damage. Besides, the mechanism of extracts' positive effects has been revealed partially.

Hydrogen Sulfide in Skin Diseases: A Novel Mediator and Therapeutic Target.

Together with nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H2S) is now recognized as a vital gaseous transmitter. The ubiquitous distributions of H2S-producing enzymes and potent chemical reactivities of H2S in biological systems make H2S unique in its ability to regulate cellular and organ functions in both health and disease. Acting as an antioxidant, H2S can combat oxidative species such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) and protect the skin from oxidative stress. The aberrant metabolism of H2S is involved in the pathogenesis of several skin diseases, such as vascular disorders, psoriasis, ulcers, pigment disorders, and melanoma. Furthermore, H2S donors and some H2S hybrids have been evaluated in many experimental models of human disease and have shown promising therapeutic results. In this review, we discuss recent advances in understanding H2S and its antioxidant effects on skin pathology, the roles of altered H2S metabolism in skin disorders, and the potential value of H2S as a therapeutic intervention in skin diseases.

Cellulose Nanocrystals for Skin Barrier Protection by Preparing a Versatile Foundation Liquid.

Most of the foundation liquids in the market need makeup removers for cleaning, while the excessive use of makeup removers might lead to skin barrier damage, which would further lead to many kinds of dermatosis, such as skin sensitivity, facial telangiectasia, rosacea, acne, as well as various cosmetic contact dermatitis. Inspired by the protective effect of fiber-rich diet on the intestinal mucosal mechanical barrier, a novel hemp/cellulose nanocrystals (CNCs)-based foundation liquid featuring easy-wiping property has been constructed, which will effectively solve the post-makeup skin cleaning problems. In this experiment, the formula of the foundation liquid can be obtained through hemp/CNCs instead of mineral oil and titanium oxide, which are considered to have undesirable local tolerance, sensitizing potential, and are environmental pollutants, to create a moisture barrier. Industrial hemp is a hot issue in cosmetic research, and a great quantity of discarded industrial hemp stalk is available to be used to produce hemp/CNCs through grinding and acidification. The graft technique is adapted to obtain hemp/CNCs-g-polylactic acid (PLA). By replacing the hydroxyl group on the side of hemp/CNCs, hemp/CNCs-g-PLA reduces the intermolecular hydrogen bonding, resulting in a higher dispersion in the oil phase. The hemp/CNCs-g-PLA has excellent performance in terms of biological compatibility, water resistance, and non-penetration into the skin. With basic features of a foundation liquid to alleviate discoloration, age spots, and skin roughness, the foundation liquid based on hemp/CNCs-g-PLA provides a novel characteristic of easy-wiping, which helps to avoid the damage to the skin barrier caused by excessive cleansing.

Premna microphylla Turcz leaf pectin exhibited antioxidant and anti-inflammatory activities in LPS-stimulated RAW 264.7 macrophages.

Premna microphylla turcz leaf juice with polysaccharides (PMPs) as its main component, are raw material of jelly-like Chinese traditional food "Guanyin tofu", which were also experiencedly used to relieve inflammation-related symptoms. Here three kinds of PMPs were extracted in alkaline (APMP), water (WPMP) and acidic (HPMP) conditions, being characteristic of RG I, high- and low-methoxyl HG pectin, respectively, in amorphous form with diverse surface microstructures, among which APMP predominantly composed of Glucose instead of galacturonic acid, showing wider molecular weight distribution and more branched chains. PMPs showed remarkable radical scavenging capability, and especially APMP at concentrations above 50 µg/mL effectively inhibited the reactive oxygen species and malondialdehyde production in LPS-stimulated RAW 264.7 macrophages, by enhancing enzymatic activities of endogenous superoxide dismutase, glutathione peroxidase and catalase, and accordingly alleviated inflammatory cytokines. Thus, PMPs could be promising non-toxic natural dietary supplement to improve chronic inflammation-induced diseases.

Ultraviolet B irradiation up-regulates MM1 and induces photoageing of the epidermis.

BACKGROUND: ΔNp63α and c-Myc are key transcription factors controlling proliferation and senescence in epithelial cells. We previously reported that the c-Myc modulator MM1 and its E3 ligase, HERC3, together with the transcription factor ΔNp63α, compose a feedback loop, which regulates proliferative senescence in MCF-10A mammary epithelial cells. However, it is unknown whether this loop is involved in skin ageing. On the other hand, ultraviolet B (UVB) rays are assumed to be the main culprits for photoageing of the epidermis, but the underlying mechanisms are obscure. AIMS: To investigate whether MM1/ΔNp63α axis is involved in UVB-induced photoageing of the epidermis. MATERIALS AND METHODS: HaCaT human immortalized keratinocytes overexpressed with MM1, knocked down with c-Myc or irradiated with UVB, were subjected to MTT assays to measure cell proliferation, as well as RT-qPCR or immunoblot to detect the members of MM1/ΔNp63α loop and the cellular senescence markers. Meanwhile, primary normal human keratinocytes (NHKs) or mice were irradiated with UVB, followed by immunoblot analysis, SA-ß-gal, haematoxylin-eosin or immunohistochemistry staining. RESULTS: Overexpression of MM1 down-regulated ΔNp63α and induced proliferative senescence in the HaCaT cells. In the HaCaT cells, NHKs and the mouse epidermis, UVB irradiation increased MM1 mRNA level and led to a down-regulation of ΔNp63α, HERC3 and c-Myc, concomitant with cellular senescence or photoageing. Additionally, knock-down of c-Myc induced proliferative senescence in the HaCaT cells and abrogated UVB-induced cellular senescence. CONCLUSIONS: UVB up-regulates MM1 and consequently modulates ΔNp63α and c-Myc, which may account for the proliferative senescence of keratinocytes and photoageing of the epidermis.