Experimental Dermatology

Vitiligo vulgaris is an autoimmune disorder characterized by the destruction of epidermal melanocytes leading to white lesions devoid of pigmentation. The destruction of epidermal melanocytes. Is driven by tissue-resident and circulatory immune cells that maintain an inflammatory milieu. Two percent of the global population suffer from vitiligo vulgaris, of which, prevalence is higher in the Indian population. Narrow-band UV-B (NBUVB) phototherapy is commonly used as an economical, non-invasive, and well-tolerated treatment modality. NBUVB promotes the migration of melanocyte stem cells (MelSC) to the epidermis, thus regaining pigmentation in affected individuals. Despite the widespread use of NBUVB in secondary and tertiary clinics in India, the status of melanocyte stem cells and immune cells, pre-and post-NBUVB is not well understood. We observe that following NBUVB phototherapy, melanocyte stem cells (pax3+) re-populate the epidermis and express melanogenesis markers (Tyrosinase, Trp2, kit) concomitant with a decrease in CD3+ T-cells within the skin. Our study reaffirms the therapeutic efficacy of NBUVB in promoting re-pigmentation in an Indian cohort of vitiligo patients. Further, NBUVB is effective in reducing overall immune load, widely considered a major contributor to the pathogenesis of the disease.

Urolithin A is a gut microbiome derived postbiotic that has been shown to stimulate mitophagy, and improve muscle and mitochondrial health when administered orally to humans. In three separate randomized trials, we have now investigated the effect of topical administration of Urolithin A on skin aging features and on UVB-mediated photodamaged skin. Post-menopausal women with evidence of skin aging such as > Grade 3 wrinkle formation were included in a split-face/arm study design in the first trial (aging study 1; n=48), followed by a second larger trial (aging study 2; n=108) in middle-aged men and women focusing on wrinkle reduction. Healthy participants were included in the placebo-controlled, randomized UVB-induced trial (photo-damage trial; n=22). Participants were randomized to receive topical supplementation with either 0.5% Urolithin A cream or placebo for 8-weeks in a low-dose arm or 1% Urolithin A cream or placebo in the high-dose arm in the aging study 1. In the aging study 2 participants were randomized to receive 1% UA in a day-cream, a night cream and a serum, that were compared to the untreated site. For the photo-damage trial, topical patches containing either 0.5% or 1% UA or placebo cream were applied for 24-hours following UVB irradiation. The primary outcome in the aging study 1 was an impact on biological pathways linked to skin aging in skin biopsies, and an impact on skin barrier function after 8-weeks. Key secondary endpoints were a change in facial wrinkle appearance (crows feet area). The aging study 2 focused on wrinkle reduction as a primary outcome. In the UVB-mediated photo-damage study, the primary read-out was the change in erythema after application. Molecular analyses were conducted on skin biopsies and using ex-vivo systems to investigate the mechanism of action mediating skin protective effects of Urolithin A. In the aging study 1, Urolithin A at 1% significantly up-regulated collagen synthesis pathways in human skin biopsies and led to a decrease in wrinkle depth on facial wrinkles. The lower dose had no significant impact. There was no change on skin barrier function with both doses suggesting maintenance of a healthy skin barrier function. In aging study 2, topical application of Urolithin A at the 1% dose in different formulations (day-cream, night cream and serum) led to significant wrinkle reduction compared to the untreated side, confirming the previous findings. Skin hydration was improved significantly as well. In the third trial, investigating impact on photodamaged skin, Urolithin A application led to a significant decrease in UV-induced erythema ([~]14%) compared to the untreated area, while placebo and lower dose UA creams showed no benefits. Urolithin A topical administration was safe and well-tolerated in all studies. UA also inhibited collagen degrading and pro-inflammatory pathways and up-regulated gene expression of biomarkers linked to induction of mitophagy and autophagy in human skin cells. Taken together, these clinical studies support the topical use of Urolithin A to manage and prolong skin health longevity by acting at the cellular level, supporting collagen structure, reducing wrinkle appearance and protecting against photoaging. The studies are registered in clinicaltrials.gov as: NCT05300984; NCT05473832; NCT05300542

Melanocytes are unique population of cells which produce melanin pigment. However, the property of melanocytes from hair follicle and epidermis, particularly, their molecular signatures remained largely unknown. In this study, we investigated the properties of epidermis and hair follicle melanocytes by biochemical and molecular biological assays. We found that epidermal melanocytes are differentiated and mature form of hair follicle melanocytes, and they are potentially related. Irradiation with NB-UVB did not induce cell death of hair follicle melanocytes as observed in epidermal melanocytes, but activate hair follicle melanocytes, promote proliferation and migration. In situ study suggested that after UVB irradiation, root sheath of hair follicles, particularly proximity of interfollicular epidermis and hair bulb become darker, suggesting migration and maturation of hair follicle melanocytes after UVB irradiation, rather than cell death. This observation provides hints and evidence to the relationship between hair follicle and epidermal melanocytes, helps to explain the contradiction of melanocytes cell death after UVB irradiation and the use of UVB in treatment of vitiligo lesion, as well as the perifollicular repigmentation phenomenon observed in vitiligo lesion after NB-UVB phototherapy.

Psoriasis is a common chronic inflammatory skin disease characterized by disturbed interactions between infiltrating immune cells and keratinocytes. To enhance our understanding of the underlying molecular and cellular mechanisms driving psoriasis pathobiology, and to identify potential biomarkers for disease severity, we conducted RNA sequencing of skin biopsies from 75 patients with psoriasis vulgaris and 46 non-psoriatic controls. To increase the robustness of the results, we meta-analysed our data with four publicly available datasets, bringing the total number of samples to 534. By comparing lesional psoriatic (PP) to healthy control (NN) skin, we identified 2269 differentially expressed genes (DEGs) (|log2FC|>1.0, FDR <0.1), and 58 DEGs when comparing non-lesional psoriatic (PN) to NN skin. We also identified 54 DEGs associated with disease severity (PASI [&ge;]10 vs. PASI <10). Cellular deconvolution analysis showed that differentiated keratinocytes emerged as the most prominent cell type among the DEGs in PP/NN. Functional enrichment analysis in PN/NN revealed several IL-17 related pathways and confirmed a previously reported pre-inflammatory signature across all psoriatic skin. This study provides insights into the psoriasis transcriptome and identifies a severity-specific signature, which may serve as candidate for future studies aimed at identifying psoriasis biomarkers and predicting disease progression.

Vitiligo is an acquired pigmentary disorder of the skin and mucus membranes. Previous study has demonstrated that autologous cultured epithelial grafts (ACEG) is an effective treatment for stable vitiligo. However, extraction of full-thickness skin might result in scar formation at donor site, which have hindered the wider application of this technology, especially for patients requiring large-area transplantation. Hair follicle as a source of keratinocyte and melanocyte, could be potential source of cells for preparation of autologous cultured sheet. Through culture system optimization, we have demonstrated maintenance of undifferentiated hair follicle-derived cells in feeder-independent culture system. After expansion, the hair follicle cells were directed to differentiate into a multi-layered, epidermis-like sheet. Cell identity, viability, purity, genomic stability, and antiseptic testing for hair follicle-derived epithelial sheet (HFES) were evaluated to ensure its safety. Immunofluorescence staining showed that basal keratinocytes were the main cell type of the autologous HFES. Optimization of culture conditions leads to increased melanocyte proliferation and functionality. Transcriptomic analysis confirmed upregulation of melanosome maturation genes. The proportions of cells are also similar to composition of cells under physiological conditions. Transplantation of HFES to depigmented areas in patients with stable vitiligo results in skin repigmentation. This technology provides a novel therapeutic option for vitiligo management.

Hyperpigmentation disorders are commonly diagnosed dermatologic conditions that can be cosmetically distressing for patients and cause negative psychosocial impacts. There is a need to better understand the underlying pathophysiology of pigmentary disorders as well as develop improvements in the management of these disorders. Here, we evaluated a p300 (CBP/p300) histone acetyltransferase (HAT) inhibitor, A-485, to determine if epigenetically targeting melanogenesis could be of therapeutic value. We find that A-485 treatment of primary human melanocytes and SK-MEL-30 melanoma cells drastically reduces the mRNA and protein expression of MITF and DCT, genes involved in melanin synthesis, and that this is accompanied by a reduction in melanin content. These results suggest that epigenetically targeting melanin synthesis with the A-485 p300 HAT inhibitor may be beneficial for the treatment of hyperpigmentation disorders.

Ultraviolet radiation (UVR) is the principal causal factor for melanoma; albeit the underlying mechanisms remain unclear. While the mutagenic properties of UVR are irrefutable, the role of UVR-induced mutations in the initiation of melanoma is controversial which highlights the gap in our knowledge of the initial critical molecular mechanisms of UVR-induced melanomagenesis. To investigate the potential non-mutational mechanisms of UVR-induced melanomagenesis, we studied the role of UVR in modulating DNA methylation changes in melanocytes via next-generation sequencing-based methodologies. Here we show that UVR directly causes stable changes in the DNA methylome and transcriptome, one month after exposure. Genomic features associated with transcription were protected from 5mC alterations whereas CpG sites found in intergenic regions were more likely to be affected. Additionally, the long-term effects of UVR seem to perturb signaling pathways important for melanocyte biology. Interestingly, UVR-sensitive CpG sites were found to be prognostic of overall patient survival and highlighted a subset of CpG sites that may be relevant in melanomagenesis. SignificanceWe report a novel finding that ultraviolet radiation (UVR) induces DNA methylation changes along with stable alterations in gene expression in cultured melanocytes. Our results provide experimental evidence of UVR-induced epigenetic rewiring, which may be implicated in the susceptibility to melanomagenesis, independently of its mutational effects. These findings offer novel insight into the role of UVR in the initiation and pathogenesis of melanoma via a currently underappreciated mechanism.

Highly specific and efficient drugs have been developed during the last two decades to treat non-communicable chronic inflammatory skin diseases (ncISD). Due to their specificity, these drugs are asking for precise diagnostic measures to attribute the most efficient treatment to each patient. Diagnosis, however, is complicated by the complex pathogenesis of ncISD and their clinical and histological overlap. Especially, precise diagnosis of psoriasis and eczema is difficult in special cases and molecular diagnostic tools need to be developed to support gold standard diagnosis of patients. In this line, we have developed a real-time based molecular classifier to distinguish psoriasis from eczema in RNA-later fixed skin samples. However, this type of skin sample is not regularly used in routine diagnostics. Therefore, we evaluated if the combination of NOS2 and CCL27 expression in lesional skin can be transferred to formalin-fixed paraffin embedded (FFPE) tissue. We present a FFPE-based molecular classifier (MC) that determines the probability for psoriasis with a specificity and sensitivity of 100% and 92%, respectively, and an area under the curve (AUC) of 0.97 delivering comparable results to the RNA-later based MC. The probability for psoriasis as well as the PCR result of NOS2 expression correlated positive with disease hallmarks of psoriasis and negative with eczema hallmarks. This tool now offers broad usage in pathology laboratories and can support diagnostic decision making on a molecular level.

BackgroundThere is growing evidence that individuals with different skin phototypes require tailored approaches to achieve optimal photoprotection. Individuals with darker skin phototypes are more prone to UVA1- and visible light-induced pigmentation, whereas lighter phototypes are more susceptible to shorter wavelengths such as UVB and UVA2. Thus, skin phototype is an important determinant of sunscreen efficacy. In the present study we have asked if ethnicity - independent of phototype - is another factor affecting sunscreen efficacy. Objectives(i) To determine the overall photoprotective effects of two sunscreen formulations against UVA1, visible light (VL), and combined visible light plus UVA1, and (ii) to compare the photoprotective efficacy of both products between Han Chinese and Caucasian participants. MethodsForty healthy volunteers (N=20 Han Chinese; N=20 Caucasian), matched for phototype, constitutive pigmentation, gender, and age, were exposed to VL, UVA1, and combined VL plus UVA1 to induce pigmentation responses following standardized irradiation protocols. Skin responses across treated and untreated sites were analysed using linear mixed-effects models. ResultsAcross all participants, both sunscreen formulations provided significant protection against VL, UVA1, and combined VL plus UVA1. Notably, photoprotective efficacy against UVA1-induced immediate (IPD) and persistent pigment darkening (PPD) differed significantly between ethnic groups, with one formulation showing stronger protection in Han Chinese. ConclusionThis study indicates that ethnicity could influence sunscreen efficacy. Thus, sunscreens should not only be tailored to different phototypes, but also consider ethnic background.

Basal cell carcinoma (BCC) represents the most commonly diagnosed human cancer among persons of European ancestry with etiology mainly attributed to sun-exposure. In this study we investigated mutations in coding and flanking regions of the PTCH1 and TP53 genes and noncoding alterations in the TERT and DPH3 promoters in 191 BCC tumors. In addition, we measured CpG methylation within the TERT hypermethylated oncological region (THOR) and transcriptions levels of the reverse transcriptase subunit. We observed mutations in PTCH1 in 59% and TP53 in 31% of the tumors. Noncoding mutations in TERT and DPH3 promoters were detected in 59% and 38% of the tumors, respectively. We observed a statistically significant co-occurrence of mutations at the four investigated loci. While PTCH1 mutations tended to associate with decreased patient age at diagnosis; TP53 mutations were associated with light skin color and increased number of nevi; TERT and DPH3 promoter with history of cutaneous neoplasms in BCC patients. TERT promoter mutations but not THOR methylation associated with an increased expression of the reverse transcriptase subunit. Our study signifies, in addition to the protein altering mutations in the PTCH1 and TP53 genes, the importance of noncoding mutations in BCC, particularly functional alterations in the TERT promoter.

Ultraviolet C (UVC) light has long been used as a sterilizing agent, primarily through devices that emit at 254 nm. Depending on the dose and duration of exposure, UV 254 nm can cause erythema and photokeratitis and potentially cause skin cancer since it directly modifies nitrogenated nucleic acid bases. Filtered KrCl excimer lamps (emitting mainly at 222 nm) have emerged as safer germicidal tools and have even been proposed as devices to sterilize surgical wounds. All the studies that showed the safety of 222 nm analyzed cell number and viability, erythema generation, epidermal thickening, the formation of genetic lesions such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts (6-4PPs) and cancer-inducing potential. Although nucleic acids can absorb and be modified by both UV 254 nm and UV 222 nm equally, compared to UV 254 nm, UV 222 nm is more intensely absorbed by proteins (especially aromatic side chains), causing photooxidation and cross-linking. Here, in addition to analyzing DNA lesion formation, for the first time, we evaluated changes in the proteome and cellular pathways, reactive oxygen species formation, and metalloproteinase (MMP) levels and activity in full-thickness in vitro reconstructed human skin (RHS) exposed to UV 222 nm. We also performed the longest (40 days) in vivo study of UV 222 nm exposure in the HRS/J mouse model at the occupational threshold limit value (TLV) for indirect exposure (25 mJ/cm2) and evaluated overall skin morphology, cellular pathological alterations, CPD and 6-4PP formation and MMP-9 activity. Our study showed that processes related to reactive oxygen species and inflammatory responses were more altered by UV 254 nm than by UV 222 nm. Our chronic in vivo exposure assay using the TLV confirmed that UV 222 nm causes minor damage to the skin. However, alterations in pathways related to skin regeneration raise concerns about direct exposure to UV 222 nm.

Patients prone to psoriasis suffer after a breakdown of the epidermal barrier and develop poorly healing lesions with abnormal proliferation of keratinocytes. Strong inflammatory reactions with genotoxicity (short telomeres) suggest impaired immune defences with DNA damage repair response (DDR) in patients with psoriasis. Recent evidence indicates the existence of crosstalk mechanisms linking the DDR machinery and hormonal signalling pathways that cooperate to influence both progressions of many diseases and responses to treatment. The aim of this study was to clarify whether steroid biosynthesis and genomic stability markers are altered in parallel during the formation of psoriatic skin. Understanding between the interaction of the steroid pathway and DNA damage response is crucial to addressing underlying fundamental issues and managing resulting epidermal barrier disruption in psoriasis. Twenty patients with psoriasis and fifteen healthy volunteers were included in this study. Transcription levels of estrogen (ESR1, ESR2), androgen (AR), glucocorticoid/mineralocorticoid receptors (NR3C1, NR3C2), HSD11B1/HSD11B2 genes, and DNA damage sensors (SMC1A, TREX1, TREX2, SSBP3, RAD1, RAD18, EXO1, POLH, HUS1) were determined by Real-Time-PCR in blood and skin samples (Lesional, non-lesional) from psoriasis and control groups. ResultsWe found that ESR1, ESR2, HSD11B1, NR3C1, NR3C2, POLH, and SMC1A transcripts were significantly decreased and AR, TREX1, RAD1, and SSBP3 transcripts were increased dramatically in the lesional skin compared to skin samples of controls. As a result, we found that the regulation of the steroidogenic pathway was disrupted in the lesional tissue of psoriasis patients and that a sufficient glucocorticoid and mineralocorticoid response did not form and the estrogen/androgen balance was altered in favour of androgens. We suggest that an increased androgen response in the presence of DDR increases the risk of developing psoriasis. Although this situation may be the cause or the consequence of a disruption of the epidermal barrier, our data suggest developing new therapeutic strategies.

BackgroundCorticotropin-releasing hormone (CRH) is involved in the regulation of immunological and cellular processes. Recently, CRH has been found to be expressed in skin cancers, where its expression appears to correlate with the degree of malignancy. ObjectiveThis study correlates CRH expression in melanoma metastases with patient survival and compares the intensity of CRH expression in melanoma to that in less aggressive skin cancer entities. MethodsTissue microarrays with cores from 94 melanomas and 40 melanocytic nevi and 51 slides from 41 basal cell carcinomas (BCC) and 10 squamous cell carcinomas (SCC) were immunohistochemically stained for CRH. The intensity of CRH expression in melanoma metastases was stratified by sex and correlated with patient survival. Furthermore, proliferation and apoptosis were assessed in CRH-stimulated A431 cells using enzyme-linked immunosorbent assays and an apoptosis detection kit. ResultsThe intensity of CRH expression was higher in primary melanomas than in melanocytic nevi. Higher CRH expression was also found in melanoma metastases from women compared to men. However, higher CRH expression was correlated with reduced overall survival only in men. Compared to melanoma, BCCs and SCCs showed weaker CRH expression, which was in line with the finding that in vitro, CRH stimulation of the A431 cells reduced their proliferative activity. ConclusionCRH does not necessarily correlate with the degree of malignancy, as semi-malignant cancers such as BCC show higher levels of CRH expression than SCCs. In melanoma, CRH expression in metastases may be an important prognostic factor for overall survival in men, which needs further evaluation. Statement of contributionMarcel Mueller and Susanne Melchers performed all experiments and wrote the first draft of the manuscript. Iris Mueller helped with the experiments and reviewed the manuscript, Jochen Utikal assembled the tissue microarrays and reviewed the manuscript, Julia Krug helped with the figures and reviewed the manuscript, and Astrid Schmieder designed and supervised the project and corrected the manuscript.

BackgroundCutaneous squamous cell carcinoma in situ (SCCIS) is a common nonmelanoma skin cancer with rising incidence and substantial treatment costs. While Mohs micrographic surgery remains the standard of care, cost, accessibility, and cosmetic concerns limit its use for some patients. Topical alternatives such as imiquimod and 5-fluorouracil are associated with variable efficacy and frequent adverse effects. ObjectiveTo evaluate the efficacy and tolerability of a 30% ascorbic acid (vitamin C) solution in 95% dimethyl sulfoxide (DMSO) for the treatment of biopsy-confirmed SCCIS. MethodsIn this open-label study, 17 patients with 27 histologically confirmed SCCIS lesions applied 30% ascorbic acid in DMSO topically twice daily for 12 weeks. Lesion size and histologic resolution were assessed by repeat biopsy at week 12. Primary outcome was complete resolution of SCCIS; secondary outcomes included lesion size reduction and adverse events. ResultsComplete histologic resolution occurred in 15 of 27 lesions (56%), while 44% of lesions showed >85% reduction in size. The mean reduction in lesion area was 71%. Only 2 lesions (7%) failed to respond. Most residual lesions demonstrated actinic atypia without carcinoma and were successfully treated with cryotherapy. No patients discontinued due to adverse effects. Ninety-four percent of participants (16/17) avoided surgical excision. ConclusionsTopical 30% ascorbic acid in DMSO demonstrated promising efficacy and excellent tolerability in the treatment of SCCIS, offering a potential noninvasive alternative to surgery. Larger, controlled trials are warranted.

BackgroundPsoriasis is a chronic immune-mediated inflammatory disease (IMID) with systemic involvement. In mild-to-moderate disease, circulating cytokines may inadequately capture systemic inflammatory burden. Composite haematological indices derived from complete blood counts, such as the systemic immune-inflammation index (SII) and systemic inflammation response index (SIRI), have emerged as sensitive prognostic markers of systemic inflammation, including in psoriasis. This exploratory post hoc analysis investigated the effects of orally administered herring roe oil (HRO), a phospholipid-rich marine oil, on systemic inflammation in patients with mild-to-moderate psoriasis utilizing these biomarkers. MethodsData were analysed from a randomized, double-blind, placebo-controlled 26-week clinical study which investigated HRO supplementation in patients (N = 64) with mild-to-moderate psoriasis (NCT03359577). SII, SIRI, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were calculated at baseline, week 12, and week 26 for patients where baseline complete blood counts (CBCs) were available (n = 60). Patients missing baseline CBCs were excluded from the analysis. Continuous changes were assessed using ANCOVA with baseline adjustment. Categorical responder analyses were performed with 25% and 30% reduction thresholds and stratification by baseline biomarker medians were performed to evaluate treatment responses and impact of baseline inflammation. ResultsCompared with placebo, HRO treatment resulted in significant mean reductions in SII, SIRI, and PLR at week 26, with supportive trends and responder effects observed as early as week 12 compared to placebo. Patients with elevated baseline inflammatory indices showed the greatest reductions in systemic inflammation. Stratification by baseline SII further revealed enhanced clinical benefit, with statistically significant PASI50 response rates in the HRO arm at week 26 among patients with lower baseline SII. ConclusionHRO supplementation was associated with a time{square}dependent reduction in systemic inflammatory biomarkers in mild{square}to{square}moderate psoriasis patients. These findings support the utility of composite inflammatory indices for monitoring systemic inflammation and suggest that baseline SII may have utility in predicting treatment response and may be a useful tool for stratification in clinical trials in mild to moderate psoriasis patients. These results could also suggest platform-potential of HRO for resolution{square}oriented interventions across several inflammatory conditions.

A phase 2, randomised, double-blind, placebo controlled trial has been conducted in mild to moderate patchy alopecia areata (AA). This demonstrated significant and dose related improvements in hair regrowth with STS01, a controlled release, topical formulation of dithranol. Here we report the results of the Alopecia Areata Symptom Impact Scale (AASIS) that assesses the severity of symptoms, daily functioning and feelings. Similar to trials in severe AA, significant improvements in hair regrowth did not translate into significant health-related quality of life (HRQoL) improvements, even in patients with complete hair regrowth, although there was some treatment-related correlation between changes in AASIS scores from baseline and clinical assessment SALT scores. The use of current HRQoL methods or indeed new measures in development for future trials, will have considerable challenges: patients may not have a true baseline at entry, may develop coping mechanisms, and there may be a delay between physical and psychological improvement.

Using broad-spectrum sunscreen is an effective practice for preventing skin cancers caused by ultraviolet (UV) radiation. Mineral sunscreens containing zinc oxide (ZnO) and titanium dioxide (TiO2) as physical UV filters are suitable for individuals with sensitive skin or allergies to chemical UV filters. Consumer compliance with sunscreen application depends largely on its cosmetic elegance, especially regarding white cast. Despite this, there is no official method to quantify white cast and help design sunscreens for diverse skin tones. To address this gap, we developed validated white cast scoring protocols that combine 1) subjective consumer feedback on formulations containing ZnO concentrations ranging from 0-30% with 2) objective L* measurements (whiteness) determined after sunscreen application. Our findings demonstrate a strong correlation between increasing ZnO percentages and higher L* values, resulting in a more visible white cast. White cast scores for the ZnO formulations were substantially consistent across both in vivo and in vitro methodologies, with higher ZnO concentrations producing unacceptable levels of white cast. This study provides a white cast scoring system as a quantitative tool for evaluating and refining mineral sunscreen formulations, contributing to the development of more cosmetically elegant sunscreens suitable for a wide range of skin tones.

Despite evidence that visible light (VL) has similar effects on human skin as those of UVA, VL is often viewed as harmless. High SPF sunscreen prevents erythema but can lead to overexposure to UVA and VL, with unknown consequences. To explore the impact of chronic blue light exposure, we irradiated (50 J/cm{superscript 2}, {lambda}= 408 nm, three times a week) human immortalized keratinocytes under acute (3 irradiations), intermediate (14 irradiations), and chronic (42 irradiations) blue-light exposure, monitoring phenotypic and gene expression changes. Chronically exposed keratinocytes exhibit increased nuclei area, chromatin alterations, higher proliferation, and apoptosis resistance, mirroring the consequences of chronic UVA exposure. While acute exposure upregulated keratinization and downregulated tissue repair and apoptosis genes, chronically exposed cells had upregulated genes involved with energy metabolism and oxidative phosphorylation and downregulated genes were enriched for immune and inflammatory responses. Specific transcriptional factors were identified in the acute and chronic stages, some of them had been associated with UVB exposure. We identified some changes in chronically irradiated keratinocytes similar to the malignant transformation, emphasizing the need for further research on the long-term impacts of blue light exposure on human skin.

Systemic sclerosis (SSc) is a complex and poorly understood disease affecting connective tissue. Patients with SSc may suffer from painful digital ulcers due to endothelial cell dysfunction and excessive extracellular matrix production through fibroblast activation, leading to skin fibrosis. To better understand the crosstalk between fibroblasts and endothelial cells in the context of SSc, we developed 3D vascularized skin organoids using SSc-derived fibroblasts from two patients. After several morphological and molecular characterizations of healthy and pathological skin organoids, we demonstrate, for the first time, that SSc patient-derived fibroblasts can trigger structural abnormalities in skin organoids that emulate some features of the disease: the vasculopathy characterized by the formation of giant capillaries and the early fibrosis associated with cytokine and chemokine secretions. It appeared that SSc-derived fibroblasts play a major role in the vascular specificities of this disease, highlighting an interesting crosstalk between these cell populations. Therefore, these SSc-fibroblast containing skin organoids may enable to gain a deeper insight into the physiopathology of SSc and provide an alternative model to animal testing to evaluate the efficacy and safety of new drugs.

BackgroundHow skin microbiota in psoriasis patients responded to systematic therapeutics remained unknown. ObjectivesTo profile temporal shifts in transcriptionally active skin microbiota in psoriasis patients receiving systemic therapies. MethodsWe prospectively enrolled 61 psoriasis patients and 29 skin-healthy controls in 2015-2019. Using RNA-based 16S rRNA gene sequencing, we analyzed 969 samples from skin lesions and compared microbial abundance and diversity by therapeutic classes and disease severity. ResultsLesional microbiota in patients on conventional systemics and TNF- inhibitor was different in relative abundances in Firmicutes (7.83% higher, adjusted P < 0.001) and Proteobacteria (6.98% lower, adjusted P < 0.01) from that in patients on anti-interleukin monoclonal antibodies (anti-ILAb) at baseline. The only difference during treatment was a 1.47% lower abundance in Bacteroides associated with nonbiologics use (adjusted P < 0.01). We identified no indicator taxa by disease severity at baseline yet noticed that a minor relative reduction in Corynebacterium sp. was associated with clinical responses to treatment. Compared to anti-ILAb, TNF- inhibitor and nonbiologics were associated with -0.21 lower Shannon Diversity (adjusted P < 0.01) and 0.03 higher Shannon Evenness (adjusted P < 0.01). Results of ordinated principal coordinates analysis revealed that, lesional microbiota from patients of these 3 therapeutic groups was compositionally distinct. Our work also demonstrated concurrent changes in clonal shifts in systemic T cell receptor clonotypes that were associated with systemic use of biologics. ConclusionsCommunity abundances and diversities of skin microbiota may be useful in distinguishing skin microbiota from patients receiving different systemic therapeutics. Specifically, use of anti-ILAb and TNF- inhibitor was associated with sample-wise microbial abundances and diversities, but not richness, over time. These findings highlighted the potential utility of skin microbiota as biomarkers for personalized treatment plans in patients with moderate-to-severe psoriasis.