Pellino-1 expression is associated with epidermal proliferation and enhanced Th17 cell infiltration in psoriatic lesions.

Pellino-1 plays a crucial role in cellular proliferation and regulates inflammatory processes. This study investigated Pellino-1 expression patterns and their relationship with CD4+ T-cell subsets in psoriasis patients. Group 1 comprised primarily biopsied psoriasis lesions from 378 patients, multiplex-immunostained for Pellino-1, CD4 and representative T helper (Th) cells (T-bet [Th1], GATA3 [Th2], and RORγt [Th17] and regulatory T cell [FoxP3] markers). Ki-67 labeling was evaluated in the epidermis. Group 2 comprised 43 Pellino-1-positive cases immunostained for Pellino-1 in both lesion and non-lesion skin biopsy samples. Five normal skin biopsies served as controls. Among 378 psoriasis cases, 293 (77.5%) were positive for Pellino-1 in the epidermis. Pellino-1-positivity was higher in psoriasis lesions than in non-lesions and normal skin (52.55% vs. 40.43% vs. 3.48%, p < 0.001; H-score, 72.08 vs. 47.55 vs. 4.40, p < 0.001, respectively). Pellino-1-positive cases also had a significantly higher Ki-67 labeling index (p < 0.001). Epidermal Pellino1-positivity was significantly associated with higher RORγt+ (p = 0.001) and FoxP3+ (p < 0.001) CD4+ T cell ratios but not T-bet+ and GATA3+ CD4+ T cell ratios. Among the CD4+ Pellino-1+ T-cell subsets, the CD4+ Pellino-1+ RORγt+ ratio was significantly associated with epidermal Pellinio-1 expression (p < 0.001). Pellino-1 expression is thus increased in psoriasis lesions and associated with increased epidermal proliferation and CD4+ T-cell subset infiltration, especially Th17 cells. This suggests that Pellino-1 could be a therapeutic target that simultaneously regulates psoriasis epidermal proliferation and immune interactions.

Mutations in SULT2B1 Cause Autosomal-Recessive Congenital Ichthyosis in Humans.

Ichthyoses are a clinically and genetically heterogeneous group of genodermatoses associated with abnormal scaling of the skin over the whole body. Mutations in nine genes are known to cause non-syndromic forms of autosomal-recessive congenital ichthyosis (ARCI). However, not all genetic causes for ARCI have been discovered to date. Using whole-exome sequencing (WES) and multigene panel screening, we identified 6 ARCI-affected individuals from three unrelated families with mutations in Sulfotransferase family 2B member 1 (SULT2B1), showing their causative association with ARCI. Cytosolic sulfotransferases form a large family of enzymes that are involved in the synthesis and metabolism of several steroids in humans. We identified four distinct mutations including missense, nonsense, and splice site mutations. We demonstrated the loss of SULT2B1 expression at RNA and protein levels in keratinocytes from individuals with ARCI by functional analyses. Furthermore, we succeeded in reconstructing the morphologic skin alterations in a 3D organotypic tissue culture model with SULT2B1-deficient keratinocytes and fibroblasts. By thin layer chromatography (TLC) of extracts from these organotypic cultures, we could show the absence of cholesterol sulfate, the metabolite of SULT2B1, and an increased level of cholesterol, indicating a disturbed cholesterol metabolism of the skin upon loss-of-function mutation in SULT2B1. In conclusion, our study reveals an essential role for SULT2B1 in the proper development of healthy human skin. Mutation in SULT2B1 leads to an ARCI phenotype via increased proliferation of human keratinocytes, thickening of epithelial layers, and altered epidermal cholesterol metabolism.

Modulators of the endocannabinoid system influence skin barrier repair, epidermal proliferation, differentiation and inflammation in a mouse model.

Endocannabinoids (ECs) are important regulators of cell signalling. Cannabinoid receptors are involved in keratinocyte proliferation/differentiation. Elevation of the endogenous cannabinoid tone leads to strong anti-inflammatory effects. Here, we explored the influence of endocannabinoid system (ECS) modulators on skin permeability barrier repair, epidermal proliferation, differentiation and inflammation in hairless mice. We used WOBE440, a selective fatty acid amide hydrolase (FAAH) inhibitor, WOL067-531, an inhibitor of endocannabinoid reuptake with no relevant FAAH activity, which both signal via cannabinoid receptor-1 and cannabinoid receptor-2 (CB-1R and CB-2R) and compared them to WOBE15 which signals via CB-2R. Barrier disruption and skin irritation were induced by tape stripping or by sodium dodecyl sulphate (SDS) patch testing. Immediately after barrier disruption, 30 µL of 0.5% WOBE440, WOL067-531 and WOBE15 solutions or the vehicle was applied topically. Barrier repair was monitored by transepidermal water loss at 1.5, 3, 5 and 7 hours. We found that barrier repair was significantly delayed by WOL067-531. A tendency for a delay was noticed for WOBE440, whereas for WOBE15, no effect was observed. Immunohistology showed that the tape-stripping-induced increase in epidermal proliferation and filaggrin expression was significantly reduced by topical applications of WOL067-531 and WOBE440, but not by WOBE15. Also, the SDS-induced inflammation, as determined by the number of inflammatory cells, was reduced by WOL067-531 and WOBE440. In summary, we showed that WOL067-531 exhibits a significant effect on skin barrier repair, epidermal proliferation/differentiation and inflammation.

Influence of Buffers of Different pH and Composition on the Murine Skin Barrier, Epidermal Proliferation, Differentiation, and Inflammation.

The pH of the skin is tightly regulated by endogenous buffering systems. We examined the influence of buffers of different pH and composition on skin barrier repair, pH, inflammation, and epidermal thickness/proliferation/differentiation. After tape-stripping in hairless mice buffers with pH 4-7 were applied in patch test chambers. After removal of the chambers, skin pH and transepidermal water loss (TEWL) were monitored for 24 h, and biopsies were taken for histology/immunohistology. Hairless mice showed a basal skin pH of about 5.8. Following barrier disruption and application of water, the pH increased by 0.6 units; increase in pH was reduced by the pH 4 glycolate buffer, unchanged by pH 4 citrate and pH 5.5 buffers, and even increased by the pH 7 buffer. pH 5.5, pH 4 citrate, and pH 4 glycolate buffers led to a slight, while the pH 7 buffer led to a significant increase in TEWL after barrier disruption compared to water. The pH 7 buffers led to a significant increase in epidermal thickness/proliferation/differentiation and inflammation after barrier disruption, whereas buffers with pH 4 and 5.5 caused a slight increase. In conclusion, only the pH 4 glycolate buffer significantly reduced the skin barrier disruption-related increase in skin pH. This was accompanied by only slight increase in epidermal thickness and inflammation compared to water. Application of the pH 7 buffer led to a significant increase in the skin pH, TEWL, epidermal thickness, and inflammation. The results are important for the formulation of topical products for effective acidification in pathological skin conditions.

Combining tape stripping and non-invasive reflectance confocal microscopy : an in vivo model to study skin damage.

BACKGROUND: Evaluation of (immuno)histological and cell biological changes in damaged skin requires often an invasive skin biopsy, making in vivo models inappropriate to study skin damage. Reflectance confocal microscopy (RCM) might overcome this limitation. Therefore, we evaluated the use of a tape-stripping model in combination with RCM to provide morphological data on skin damage and recovery. METHODS: In 25 volunteers, a tape-stripping stimulus was applied. The skin was imaged with RCM during 1 week and 3 mm punch biopsies were obtained. RESULTS: Strong correlations between epidermal thickness determined by RCM and conventional histological measurements were found. RCM thickness measurements correlated well with epidermal proliferation. The 10× or 15× repeated tape-stripping resulted in skin damage similar to acute stripping. Mild repeated tape-stripping showed no skin damage. CONCLUSION: Overall, we demonstrated that non-invasive RCM in combination with tape-stripping could be used as model to obtain morphological and cell biological data on skin-material interactions.

Regulation of epidermal proliferation and hair follicle cycling by synthetic photostable retinoid EC23.

BACKGROUND: Retinoid signaling is an important regulator of the epidermis and skin appendages. Therefore, synthetic retinoids have been developed for therapeutic use for skin disorders such as psoriasis and acne. AIMS: In previous studies, we showed how the photostable retinoid EC23 induces neuronal differentiation in stem cell-like cell populations, and here, we aim to investigate its ability to influence epidermal and hair follicle growth. METHODS: EC23 influence on skin biology was investigated initially in cultures of monolayer keratinocytes and three-dimentional in vitro models of skin, and finally in in vivo studies of mice back skin. RESULTS: EC23 induces keratinocyte hyperproliferation in vitro and in vivo, and when applied to mouse skin increases the number of involucrin-positive suprabasal cell layers. These phenotypic changes are similar in skin treated with the natural retinoid all-trans retinoic acid (ATRA); however, EC23 is more potent; a tenfold lower dose of EC23 is sufficient to induce epidermal thickening, and resulting hyperproliferation is sustained for a longer time period after first dose. EC23 treatment resulted in a disorganized stratum corneum, reduced cell surface lipids and compromised barrier, similar to ATRA treatment. However, EC23 induces a rapid telogen to anagen transition and hair re-growth in 6-week-old mice with synchronously resting back skin follicles. The impact of EC23 on the hair cycle was surprising as similar results have not been seen with ATRA. CONCLUSIONS: These data suggest that synthetic retinoid EC23 is a useful tool in exploring the turnover and differentiation of cells and has a potent effect on skin physiology.

The Epidermal Proliferation and the Number of Langerhans Cells in 7, 12-dimethylbenzanthracene Induced Epidermal Changes

Chemically induced epiderml carcinogenesis is usually divided into two stages, the initiation and promotion. The initiation involves conversion of some epidermal cells into latent neoplastic cells and the promotion is proliferation of the transformed cells. As immunosurveillence is thought to be a host defense against tumors, Langerhans cells, being essential in initiation of local cutaneous immunologic reaction, is suggested to be important in the carcingenesis of the epidermis. This study is attempted to investigate the epidermal proliferative changes in mice induced by application of 12-0-tetradecanoy1-phorbol-13-acetate(TPA) on the skin initiated with 7, 12-dimethylbenzanthracene(DMBA) and its relationship with Langerhans cell. Ninty five male inbred BALB/c mice weighing 20~25 g were divided into five groups; the 33 week-group, the 21 week-group, the 12 week-group and the 4 week-group according to the duration of carcinogen application, and the control group. The carcingen was applied with a brush on the dorsal skin of mice after depilation. Ten days after application of 800 nmole DMBA in 0.4 cc acetone, 20 nmole TPA in 0.4 cc acetone was applied twice per week and the control group was applied with the same amount of acetone for 4 weeks. Animals were sacrificed 3 days after the last application of TPA. One hour before sacrifice, bromodeoxyuridine(BrdU) (1 mg/g) was injected via the tail artert for BrdU stain of S phase cells. A strip of dorsal skin was used for hematoxylineosin stain, immunohistochemical stain for BrdU and la antigen of Langerhans cell, and flow cytometry. The results are as follows: 1. Cellular proliferation, hyperkeratosis and dysplasia of the epidermis were increased in relation to duration of carcingen application. Papillomas were developed 12 weeks after application of the carcingen. 2. BrdU labelling and proliferative indices of the 20 weeks' application group were significantly higher than those of the 12 weeks' application group. The number of Langerhans cell was decreased markedly ater 4 week' application of the carcinogen. 3. All epiedrmal lesions including a case of squamous cell carcinoma were diploidy in flow cytometry. It is thought that disturbance of immunosurveillence, caused by depletion of Langerhans cell, may permit proliferation of epidermal cells. Although abnormal quantitative change of nuclear DNA has not occurred even when the epidermal proliferative activity and dysplastic change were increased markedly, it is thought that the occurrence of structural change of chromosome is remained to be clarified.