Steroid sulfatase deficiency causes cellular senescence and abnormal differentiation by inducing Yippee-like 3 expression in human keratinocytes.

Human steroid sulfatase (STS) is an enzyme that catalyzes the hydrolysis of dehydroepiandrosterone sulfate (DHEAS), estrone sulfate (E1S), and cholesterol sulfate. Abnormal expression of STS causes several diseases including colorectal, breast, and prostate cancer and refractory skin disease. In particular, accumulation of intracellular cholesterol sulfate by STS deficiency leads to a skin disorder with abnormal keratinization called X-linked ichthyosis (XLI). To determine the detailed mechanisms of XLI, we performed RNA sequencing (RNA-seq) analysis using human keratinocyte HaCaT cells treated with cholesterol and cholesterol sulfate. Of the genes with expression changes greater than 1.5-fold, Yippee-like 3 (YPEL3), a factor expected to affect cell differentiation, was found. Induction of YPEL3 causes permanent growth arrest, cellular senescence, and inhibition of metastasis in normal and tumor cells. In this study, we demonstrate that YPEL3 expression was induced by STS deficiency and, using the CRISPR/Cas9 system, a partial knock-out (STS+/-) cell line was constructed to establish a disease model for XLI studies. Furthermore, we show that increased expression of YPEL3 in STS-deficient cell lines promoted cellular senescence and expression of keratinization-related proteins such as involucrin and loricrin. Our results suggest that upregulation of YPEL3 expression by STS deficiency may play a crucial role in inducing cellular senescence and abnormal differentiation in human keratinocytes.

Pyrrolidone carboxylic acid levels or caspase-14 expression in the corneocytes of lesional skin correlates with clinical severity, skin barrier function and lesional inflammation in atopic dermatitis.

BACKGROUND: Dry skin in atopic dermatitis (AD) mainly results from barrier impairment due to deficiency of ceramide and natural moisturizing factors including pyrrolidone carboxylic acid (PCA) in stratum corneum (SC). Caspase-14 cleaves filaggrin monomers to free amino acids and their derivatives such as PCA, contributing natural moisturizing factors. Cytokines in the corneocytes represent cutaneous inflammation severity of AD patients. OBJECT: To analyze the correlations of PCA, caspase-14 and cytokines in corneocytes with clinical severity, barrier function and skin inflammation, those were quantitated. METHODS: A total of 73 persons were enrolled: 21 patients with mild AD, 21 with moderate-to-severe AD, 13 with X-linked ichthyosis (XLI) as a negative control for filaggrin gene (FLG) mutation, and 18 healthy controls. Skin barrier functions such as basal transepidermal water loss (TEWL), stratum corneum (SC) hydration and skin surface pH were measured. To collect corneocytes, stripping with D-squame discs was done on lesional and non-lesional skin. And then PCA was isolated from D-squame discs and quantitated by LC-MS/MS. Cytokine assays were performed. RESULTS: The quantity of PCA and caspase-14 was decreased in inflammatory lesions compared to non-lesion in AD patients. And the amounts of PCA and caspase-14 in the lesion of AD patients correlated with clinical severity as determined by eczema area and severity index score and the skin barrier functions. Also, the expressions of TNF-α and IL-13 inversely correlated with PCA quantity. CONCLUSION: The quantity of PCA or caspase-14 in the corneocytes of the lesional skin of AD patients reflects the clinical severity, skin barrier function and the degree of lesional inflammation.

Ichthyosis follicularis, alopecia, and photophobia syndrome: a case report and a pathological insight into pilosebaceous anomaly.

Ichthyosis follicularis, alopecia, and photophobia (IFAP) syndrome (OMIM 308205) is an extremely rare X-linked oculocutaneous genetic disorder characterized by follicular keratotic papules, total to subtotal alopecia, and photophobia. Previous reports depicted the histopathological features of affected skin lesions, represented by marked follicular plugging and hypoplastic pilosebaceous structures. However, past studies provided limited pathological information of pilosebaceous unit anomaly. Here, we report a 3-year-old boy's case with this uncommon condition. In this case, scalp biopsy samples were processed by both vertical and transverse sectioning techniques, which enabled a more detailed and quantitative pathological analysis of pilosebaceous structures. In vertical slices, miniaturized anagen hair follicles with characteristic follicular plugs were observed. A transverse section identified abortive sebaceous glands in hair follicles, a finding rarely observed in vertical sections. In addition, a transverse slice demonstrated that the number of total hair follicles was not significantly decreased compared with the average hair follicle density in Asians, suggesting that the pilosebaceous hypoplasia might arise from impaired maturation, not from initiation defect, during hair follicle morphogenesis. This study provides a more comprehensive pathological insight into pilosebaceous anomaly in IFAP syndrome and substantiats the usefulness of the combination of vertical and transverse sectioning approaches in the pathological examination of congenital hypotrichosis, including IFAP syndrome.

Nephrotic syndrome with X-linked ichthyosis, Kallmann Syndrome and unilateral renal agenesis.

We describe a 10-year-old boy with X-linked ichthyosis, Kallmann Syndrome and unilateral renal agenesis who presented with nephrotic syndrome. DNA analysis revealed deletion of the Steroid Sulfatase (STS) gene. STS deficiency in X-linked ichthyosis leads to cholesterol sulfate accumulation, which induces transglutaminase-1 dysfunction. Since the slit diaphragm of the glomerular epithelial cell is a modified adherens junction, the accumulation of cholesterol sulfate could interfere with the normal slit diaphragm function of the glomerular visceral epithelial cell, resulting in nephrotic range proteinuria. The child went into remission on oral prednisolone.

End-stage renal failure in a child with X-linked ichthyosis.

We describe an 8-year-old boy who presented with steroid-resistant nephrotic syndrome (SRNS) associated with X-linked ichthyosis (XLI). At birth, the patient exhibited scaly skin, cryptorchidism, and steroid sulfatase (STS) deficiency. DNA analysis showed deletion of exons 1-10 of the STS gene. Proteinuria developed at 6 years and was resistant to steroid therapy. Kidney biopsy findings prior to steroid therapy were compatible with minimal change nephrotic syndrome. By immunofluorescence, glomerular basement membranes exhibited diffuse linear staining for the alpha5 chain of collagen IV, making X-linked Alport syndrome an unlikely explanation for the association of SRNS and ichthyosis. Despite immunosuppressive therapy together with oral prednisolone, no clinical response was achieved. He rapidly reached end-stage renal failure and finally underwent renal transplantation. We propose that SRNS should be considered as one of the highly variable phenotypes associated with XLI.

Assessment of the clinical effect of topical tacalcitol on ichthyoses with retentive hyperkeratosis.

BACKGROUND: Topical tacalcitol (1alpha,24-dihydroxyvitamin D3) has been demonstrated to produce beneficial clinical effects on epidermo-hyperproliferative disorders such as psoriasis and pityriasis rubra pilaris. However, the efficacy of the agent has not been elucidated in retentive hyperkeratotic disorders. OBJECTIVE: The object of the study was to assess the clinical efficacy of topical tacalcitol against ichthyoses with retentive hyperkeratosis; X-linked ichthyosis (XLI), ichthyosis vulgaris (IV), and acquired ichthyosis (AI). METHODS: Tacalcitol was topically applied on 9 patients with the retention ichthyoses, using a single-blinded, bilaterally paired approach with right-left comparison of tacalcitol and the base. RESULTS: Clinical improvement obtained by topical tacalcitol exclusively was not superior to that of the vehicle alone in any of the ichthyotic patients. CONCLUSION: Topical tacalcitol therapy was ineffective against ichthyoses without epidermal hyperproliferation.

X-linked dominant ichthyosis with peroxisomal deficiency. An ultrastructural and ultracytochemical study of the Conradi-Hünermann syndrome and its murine homologue, the bare patches mouse.

BACKGROUND AND DESIGN: The bare patches (Bpa) mouse expresses an X-dominant disorder that may be homologous to the Conradi-Hünermann (CH) syndrome in man; ie, both express ichthyosis, cataracts, and skeletal defects. To confirm their homology, we compared the light and electron microscopy of involved (I) vs uninvolved (U) skin from an infant with CH syndrome to Bpa mice during and after resolution of the scaling disorder. The peroxisomal content of Bpa and CH skin was evaluated by diaminobenzidine (DAB) ultracytochemistry (Bpa only) and by assessment of catalase (Bpa only) and dihydroxyacetone phosphate-acyltransferase (DHAP-AT) activities in cultured I vs U fibroblasts. RESULTS: Both CH and Bpa I epidermis exhibited psoriasiform features. In addition, ultrastructurally both exhibited the following: (1) vacuolated lamellar bodies, (2) dilatation of intercellular spaces by vesicular structures and amorphous debris, and (3) abnormal mitochondria. Stratum corneum interstices were filled with vesicular structures, and no lamellar unit structures were evident using ruthenium tetroxide postfixation. Peroxisomes were poorly stained by DAB in I Bpa epidermis and dermis during the eruptive phase. Moreover, catalase and DHAP-AT activities in cultured I Bpa fibroblasts were decreased to 40% and 30% of U Bpa levels, respectively; DHAP-AT activity in cultured I CH fibroblasts was also reduced (60% of U CH). With resolution of the scaling disorder, the ultrastructural and ultracytochemical features of I and U Bpa skin became indistinguishable. CONCLUSIONS: These studies provide evidence for a self-resolving defect involving multiple organelles, including lamellar bodies, peroxisomes, and mitochondria in the I skin of CH syndrome and the Bpa mouse.

Child with manifestations of dermotrichic syndrome and ichthyosis follicularis-alopecia-photophobia (IFAP) syndrome.

We report on a boy with short stature, mental retardation, seizures, follicular ichthyosis, generalized alopecia, hypohydrosis, enamel dysplasia, photophobia, congenital aganglionic megacolon, inguinal hernia, vertebral, renal and other anomalies, and a normal chromosome constitution. The clinical findings include all the features that dermotrichic and ichthyosis follicularis-alopecia-photophobia (IFAP) syndrome have in common and in addition those that characterize IFAP syndrome (photophobia, recurrent respiratory infections, etc.), those that are present only in dermotrichic syndrome (nail anomalies, hypohydrosis, megacolon, vertebral defects, etc.) and additional ones (enamel dysplasia, renal anomalies, inguinal hernia, etc.). Two maternal uncles were referred as being affected by alopecia and ichthyosis suggesting X-linked recessive transmission. Various hypotheses concerning the relationship between the 2 syndromes and the present case are discussed.