OSBPL2 compound heterozygous variants cause dyschromatosis, ichthyosis, deafness and atopic disease syndrome.

PURPOSE: In this study, we identified and diagnosed a novel inherited condition called Dyschromatosis, Ichthyosis, Deafness, and Atopic Disease (DIDA) syndrome. We present a series of studies to clarify the pathogenic variants and specific mechanism. METHODS: Exome sequencing and Sanger sequencing was conducted in affected and unaffected family members. A variety of human and cell studies were performed to explore the pathogenic process of keratosis. RESULTS: Our finding indicated that DIDA syndrome was caused by compound heterozygous variants in the oxysterol-binding protein-related protein 2 (OSBPL2) gene. Furthermore, our findings revealed a direct interaction between OSBPL2 and Phosphoinositide phospholipase C-beta-3 (PLCB3), a key player in hyperkeratosis. OSBPL2 effectively inhibits the ubiquitylation of PLCB3, thereby stabilizing PLCB3. Conversely, OSBPL2 variants lead to enhanced ubiquitination and subsequent degradation of PLCB3, leading to epidermal hyperkeratosis, characterized by aberrant proliferation and delayed terminal differentiation of keratinocytes. CONCLUSIONS: Our study not only unveiled the association between OSBPL2 variants and the newly identified DIDA syndrome but also shed light on the underlying mechanism.

A Case of Paradoxical Reactions to Biologic Therapy for Psoriasis.

Introduction: Psoriasis is an immune-mediated chronic inflammatory skin disease. As our understanding of the pathogenesis of psoriasis has improved, biologic agents have become increasingly important in the treatment of psoriasis. However, the use of biologic agents is associated with cutaneous side effects. A new type of side effect called paradoxical reactions is an emerging threat arising from the increasing use of biologic agents. Case: Here, we present a case of paradoxical skin reactions - pyoderma gangrenosum (PG) and eczema - induced by biologic therapy. The case was successfully and eventually treated with baricitinib. Discussion: PG is a rare inflammatory disease characterised by painful and necrotic ulcerations containing neutrophils. It has been associated with autoimmune diseases such as inflammatory bowel disease (IBD). TNF (tumor necrosis factor) -α inhibitors can effectively treat refractory PG, while IL (interleukin) -17A inhibitors may worsen IBD symptoms. The cause of PG in this case was believed to be secukinumab, not adalimumab. The patient was diagnosed with eczematous dermatitis due to TNF-α inhibitors, and baricitinib was added to treat eczematous dermatitis. Conclusion: Paradoxical reactions are unpredictable events that may occur during treatment with biologics at anytime. They need further research in order to formulate personalised treatment.

Biallelic mutations in LSS in autosomal-recessive mutilating palmoplantar keratoderma.

Mutilating palmoplantar keratoderma (PPK) is a heterogeneous genetic disease that poses enormous challenges to clinical diagnosis and genetic counselling. Lanosterol synthase (LSS) gene encodes LSS involved in the biosynthesis pathway of cholesterol. Biallelic mutations in LSS were found to be related to diseases such as cataracts, hypotrichosis and palmoplantar keratoderma-congenital alopecia syndrome. The aim of this study was to investigate the contribution of the LSS mutation to mutilating PPK in a Chinese patient. The clinical and molecular characteristics of the patient were evaluated. A 38-year-old male patient with mutilating PPK was recruited in this study. We identified biallelic variants in the LSS gene (c.683C > T, p.Thr228Ile and c.779G > A, p.Arg260His). Immunoblotting revealed that the Arg260His mutant showed a significantly reduced expression level while Thr228Ile showed an expression level similar to that of the wild type. Thin layer chromatography revealed that mutant Thr228Ile retained partial enzymatic activity and mutant Arg260His did not show any catalytic activity. Our findings show the correlation between LSS mutations and mutilating PPK.

A Novel Variant and a Missense Variant Identified in the DKC1 Gene in Three Chinese Familieswith Dyskeratosis Congenita.

Purpose: Dyskeratosis congenita (DC) is an inherited telomere biology disorder characterized clinically by mucocutaneous triad of reticulate hyperpigmentation, nail changes and oral leukoplakia. Bone marrow failure, pulmonary fibrosis and malignancies are the mainly life-threatening causes. There are X-linked recessive, autosomal dominant and autosomal recessive patterns of DC. DKC1 is the most common pathogenic mutation gene responsible for X-linked DC, and it encodes a protein, dyskerin, which is a component of telomerase holoenzyme complex essential for telomere maintenance. Patients with DC have very short telomeres, but the precise pathogenic mechanism remains unclear. This study aimed to identify the causative mutations in the DKC1 gene in three Chinese families with the X-linked form of DC. Patients and Methods: Three Chinese families with DC were included in this study. Whole exome sequencing and Sanger sequencing were performed to clarify the mutation of DKC1 gene. Measurement of relative telomere length through qPCR. Predictions of protein structure and function were performed using bioinformatics tools, including I-TASSER, Polyphen-2 and SIFT. Results: There were four males with DC and a female carrier in three Chinese pedigrees. The novel mutation c.92A>C (p. Q31P) and the missense mutation c.1058C>T (p. A353V) in DKC1 were identified. Both mutations locally changed the structure of dyskerin. Variant Q31P and A353V were predicted to have "deleterious" and "natural" effects on the function of dyskerin, respectively. Conclusion: The novel variant and missense variant detected in the DKC1 gene improve our understanding of DC and broaden the mutation spectrum of the DKC1 gene.

Autoreactive B Cell Differentiation in Diffuse Ectopic Lymphoid-Like Structures of Inflamed Pemphigus Lesions.

Pemphigus is an organ-specific autoimmune disease that targets skin and/or mucous membranes. Our previous study showed that infiltrating lymphocytes in pemphigus vulgaris (PV) lesions produce anti-desmoglein (Dsg) 1/3 antibodies after in vitro culture. In this study, we found diffuse ectopic lymphoid-like structures (ELSs) commonly present in the lesions of both PV and pemphigus foliaceus. Notably, pemphigus lesions contained centroblasts, plasmablasts, and plasma cells, which recapitulated the different stages of B cell differentiation. Elevated mRNA expression levels of the differentiation-related transcription factors BLIMP-1, IRF4, and BCL-6 were observed in pemphigus lesions. Moreover, B cell receptor repertoire analysis revealed the clonal expansion of the lesional B cells. Lesional B cells might recirculate among lesions, lymph nodes, and peripheral blood. Increased mRNA expression levels of multiple chemokines in pemphigus lesions and elevated expression levels of chemokine receptors on lesional B cells were also observed. Collectively, these results show that the ELSs in pemphigus lesions might act as a niche, supporting in situ B cell differentiation and clonal expansion.

Pivotal Role of Lesional and Perilesional T/B Lymphocytes in Pemphigus Pathogenesis.

Pemphigus is a skin and mucosal membrane-targeting autoimmune bullous disease. Previous studies have shown that circulating anti-desmoglein1/3 antibodies are pathogenic and mediate blister formation. However, the role of infiltrating immune cells in lesional skin has not been fully investigated. In this study we showed that there existed a large number of B and T lymphocytes and plasma cells in the skin lesions by immunohistochemistry and immunofluorescence staining. In addition, a significantly increased number of Dsg1- and Dsg3-specific B cells could be identified by flow cytometric analysis or enzyme-linked immunospot technique (i.e., ELISPOT) assay. Furthermore, anti-Dsg1 and Dsg3 antibodies could be detected from the supernatant of in vitro cultures with isolated lymphocytes from lesional skin. We found that most T lymphocytes infiltrating pemphigus vulgaris lesions were CD4+ T helper cells expressing IL-21 and IL-17a but not typical T follicular helper cells expressing CXCR5. Additionally, our microarray assay showed that the level of chemokine CCL19 was significantly elevated, suggesting active T-/B-lymphocyte trafficking and aggregation in the pemphigus vulgaris lesions. Collectively, our results suggest a critical role of locally infiltrating lymphocytes in pemphigus pathogenesis.

[The expression and significance of beta2-AR and VEGFR-2 in infantile hemangioma].

OBJECTIVE: To investigate the significance of beta-adrenergic receptor 2 (beta2-AR) and vascular endothelial growth factor-2 (VEGFR-2) in the occurrence and development of infantile hemangioma through detecting the expression of beta2-AR and VEGFR-2 in the different stages of infantile hemangiomas. METHODS: According to the Mulliken's classification standard, we classified the specimens as proliferating group (32 cases), involuting group (17 cases) and involuted group (11 cases). Normal skin tissue surrounding the hemangioma from 7 cases were chosen as control group. The expression of beta2-AR and VEGFR-2 was detected by immunohistochemical technique in proliferating hemangioma, involuting hemangioma, involuted hemangioma. The mean optical density was measured by image analysis system (Image Pro Plus 6.0) and SPSS 16.0 software was applied for statistical analysis. RESULTS: The expression of beta2-AR and VEGFR-2 was strongly positive in proliferating hemangioma, while positive in involuting hemangioma and weakly positive in the involuted stage. The mean optical density of each phase was 0.064 751 2 +/- 0.012 747, 0.031 6017 +/- 0.006 848,0.011 869 8 +/- 0.039 349 for beta2-AR, and 0.068 940 9 +/- 0.029 274, 0.028 445 5 +/- 0.006 396, 0.011 184 1 +/- 0.004 198 for VEGFR-2. The differences between different stages had a statistically significance (P < 0.05). Correlation analysis on the mean optical density between beta2-AR and VEGFR-2 had a statistically significance (P < 0. 05). CONCLUSIONS: Beta2-AR and VEGFR-2 may be involved in the occurrence and development of infantile hemangioma.