Collagen is More Abundant and Structurally Altered in Lichen Sclerosus.

OBJECTIVE: To test the hypothesis that genital skin and male urethra affected by lichen sclerosus (LS) has increased collagen content and altered collagen structure. METHODS: We used picrosirius red to stain and image collagen in human urethral, vulvar, and foreskin specimens with and without LS. Using Image J software, we quantified and compared (1) collagen content (using 2o metrics: collagen proportionate area [CPA] and collagen fiber count), (2) collagen fiber length and width, and (3) collagen structure using the texture analysis technique gray level co-localization matrix (GLCM) with respect to LS status and tissue type. RESULTS: We analyzed 23 LS specimens (vulva n=9, urethra n=7, foreskin n=7) and 29 non-LS specimens (vulva n=9, urethra n=7, foreskin n=13). Fiber count and CPA were significantly higher in all LS specimens compared to non-LS specimens (CPA: mean±SD 0.971±0.03 vs 0.948±0.02, P < .007; fiber count: mean±SD = 2906±127 vs 2509±78 fibers; P = .003). Collagen fiber width and length were similar with respect to LS status. GLCM analysis showed decreased inverse difference moment and increased entropy in LS tissues indicative of less homogeneous and more disorganized tissue structure (P<.001). CONCLUSION: LS tissues have greater collagen content compared to non-LS tissues. Quantitative assessment of collagen organization, using GLCM, revealed less homogeneity and more disorganization of collagen in LS compared to non-LS tissues. Taken together, our findings suggest that alterations in physical tissue properties seen in LS may be due to both increased collagen abundance and altered structure.

Reduced SPAG17 Expression in Systemic Sclerosis Triggers Myofibroblast Transition and Drives Fibrosis.

Systemic sclerosis (SSc) is a clinically heterogeneous fibrotic disease with no effective treatment. Myofibroblasts are responsible for unresolving synchronous skin and internal organ fibrosis in SSc, but the drivers of sustained myofibroblast activation remain poorly understood. Using unbiased transcriptome analysis of skin biopsies, we identified the downregulation of SPAG17 in multiple independent cohorts of patients with SSc, and by orthogonal approaches, we observed a significant negative correlation between SPAG17 and fibrotic gene expression. Fibroblasts and endothelial cells explanted from SSc skin biopsies showed reduced chromatin accessibility at the SPAG17 locus. Remarkably, mice lacking Spag17 showed spontaneous skin fibrosis with increased dermal thickness, collagen deposition and stiffness, and altered collagen fiber alignment. Knockdown of SPAG17 in human and mouse fibroblasts and microvascular endothelial cells was accompanied by spontaneous myofibroblast transformation and markedly heightened sensitivity to profibrotic stimuli. These responses were accompanied by constitutive TGF-ß pathway activation. Thus, we discovered impaired expression of SPAG17 in SSc and identified, to our knowledge, a previously unreported cell-intrinsic role for SPAG17 in the negative regulation of fibrotic responses. These findings shed fresh light on the pathogenesis of SSc and may inform the search for innovative therapies for SSc and other fibrotic conditions through SPAG17 signaling.