A mouse organotypic tissue culture model for autosomal recessive congenital ichthyosis

Effects on skin of Stichopus japonicus viscera extracts detected with saponin including Holothurin A: Down-regulation of melanin synthesis and up-regulation of neocollagenesis mediated by ERK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Stichopus japonicus (sea cucumber), edible traditional food in Asia, and its extracts are renowned for their wound healing, pain relieving, and cosmetic effects in traditional medicine. Holothurins, toxins isolated from sea cucumber, are thought to be active components for their beneficial effects. However, researchers have yet to outline specific mechanisms thereof.

AIM OF THE STUDY

The present study was designed to evaluate the anti-melanogenic and anti-wrinkle properties of S. japonicus viscera extracts (VF) on the skin via in vitro and ex vivo experiments and to assess the anti-aging effects of S. japonicus viscera extracts in relation to known wound healing and cosmetic processes.

MATERIALS AND METHODS

The viscera of live S. japonicus specimens were freeze dried and ground into a powder. Aqueous extracts were subsequently prepared from the concentrated powder using a water extraction method. To investigate the inhibitory effects of VF on melanogenesis, mushroom tyrosinase activity assay and melanin assay were performed on Melan-A cells. To further delineate the anti-melanogenic properties of VF, western blot analysis for tyrosinase, TRP-1, TRP-2, MITF, and ERK was conducted. Changes in collagen synthesis in human dermal fibroblast (HDF) were evaluated via CCK-8 assay and immunocytochemistry to determine the anti-wrinkle effects of VF. Finally, anti-aging properties were examined in a human skin equivalent ex vivo model.

RESULTS

In Melan-A cells, VF treatment reduced melanin contents in a concentration-dependent manner. The anti-melanogenic effects of VF appeared to be due to enzymatic inhibition of tyrosinase. In CCK-8 assay, VF also significantly increased the viability of HDFs in a concentration-dependent manner. Immunoblot analysis revealed phosphorylation of ERK in HDFs treated with VF. In a human skin equivalent ex vivo model (Neoderm®-ED), VF treatment at a concentration of 50 μg/ml enhanced collagen type IV and Ki-67 expression and downregulated MMP-9 expression.

CONCLUSION

This study demonstrated that aqueous extracts from S. japonicus viscera are effective whitening and anti-aging agents that stimulate ERK signaling to inhibit melanin synthesis and promote collagen synthesis.

Development of a new model of reconstituted mouse epidermis and characterization of its response to proinflammatory cytokines

The development of three-dimensional models of reconstituted mouse epidermis (RME) has been hampered by the difficulty to maintain murine primary keratinocyte cultures and to achieve a complete epidermal stratification. In this study, a new protocol is proposed for the rapid and convenient generation of RME, which reproduces accurately the architecture of a normal mouse epidermis. During RME morphogenesis, the expression of differentiation markers such as keratins, loricrin, filaggrin, E-cadherin and connexins was followed, showing that RME structure at day 5 was similar to those of a normal mouse epidermis, with the acquisition of the natural barrier function. It was also demonstrated that RME responded to skin-relevant proinflammatory cytokines by increasing the expression of antimicrobial peptides and chemokines, and inhibiting epidermal differentiation markers, as in the human system. This new model of RME is therefore suitable to investigate mouse epidermis physiology further and opens new perspectives to generate reconstituted epidermis from transgenic mice.

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.

An IL-17-dominant immune profile is shared across the major orphan forms of ichthyosis

BACKGROUND

The ichthyoses are rare genetic disorders associated with generalized scaling, erythema, and epidermal barrier impairment. Pathogenesis-based therapy is largely lacking because the underlying molecular basis is poorly understood.

OBJECTIVE

We sought to characterize molecularly cutaneous inflammation and its correlation with clinical and barrier characteristics.

METHODS

We analyzed biopsy specimens from 21 genotyped patients with ichthyosis (congenital ichthyosiform erythroderma, n = 6; lamellar ichthyosis, n = 7; epidermolytic ichthyosis, n = 5; and Netherton syndrome, n = 3) using immunohistochemistry and RT-PCR and compared them with specimens from healthy control subjects, patients with atopic dermatitis (AD), and patients with psoriasis. Clinical measures included the Ichthyosis Area Severity Index (IASI), which integrates erythema (IASI-E) and scaling (IASI-S); transepidermal water loss; and pruritus.

RESULTS

Ichthyosis samples showed increased epidermal hyperplasia (increased thickness and keratin 16 expression) and T-cell and dendritic cell infiltrates. Increases of general inflammatory (IL-2), innate (IL-1β), and some T_H1/interferon (IFN-γ) markers in patients with ichthyosis were comparable with those in patients with psoriasis or AD. TNF-α levels in patients with ichthyosis were increased only in those with Netherton syndrome but were much lower than in patients with psoriasis and those with AD. Expression of T_H2 cytokines (IL-13 and IL-31) was similar to that seen in control subjects. The striking induction of IL-17-related genes or markers synergistically induced by IL-17 and TNF-α (IL-17A/C, IL-19, CXCL1, PI3, CCL20, and IL36G; P < .05) in patients with ichthyosis was similar to that seen in patients with psoriasis. IASI and IASI-E scores strongly correlated with IL-17A (r = 0.74, P < .001) and IL-17/TNF-synergistic/additive gene expression. These markers also significantly correlated with transepidermal water loss, suggesting a link between the barrier defect and inflammation in patients with ichthyosis.

CONCLUSION

Our data associate a shared T_H17/IL-23 immune fingerprint with the major orphan forms of ichthyosis and raise the possibility of IL-17-targeting strategies.