CCN3-derived peptide BLR-200 impairs YAP activation and attenuates bleomycin-induced skin fibrosis through blocking the generation of Sfrp2-positive fibroblasts

An autocrine pro-adhesive/pro-contractile signaling loop, through the mechanosensitive transcriptional cofactor YAP, promotes fibrosis. The CCN family of matricellular proteins modify adhesive signaling. Of these, CCN3 is antifibrotic. We show that BLR-200, a CCN3-derived peptide, has anti-fibrotic properties in the bleomycin-induced model of scleroderma skin fibrosis. In vitro, BLR-200 delayed, but did not abolish, fibroblast adhesion to collagen and nuclear YAP localization. In vivo, BLR-200 prevented/treated bleomycin-induced skin fibrosis, and reduced bleomycin-induced expression of profibrotic genes including -smooth muscle actin, CCN1 and CCN2. Lineage tracing and scRNA-seq analyses revealed that the myofibroblasts in this model were quantitatively derived from collagen-lineage Pi16+/Col15+ve fibroblasts. BLR-200 prevented myofibroblast differentiation in this model and trajectory of fibroblasts toward a Sfrp2-positive subset, a cell type associated with poor clinical outcome. BLR-200 impairs YAP activation in vitro and appearance of translationally-relevant fibroblast subtypes in vivo and is a novel anti-fibrotic agent for SSc skin fibrosis. HIGHLIGHTS-SSc skin fibrosis, a major unmet need, is driven by an activated mechanotransduction/YAP pathway; how to block this pathway clinically is unclear -members of the CCN family of matricellular proteins are adhesive signaling modifiers; herein, we identify BLR-200, a synthetic peptide derived from CCN3, based on its ability to impair, but not ablate, YAP nuclear localization and fibroblast spreading/attachment to collagen -BLR-200 blocks and treats progression of bleomycin-induced skin fibrosis -In the bleomycin model, lineage tracing analysis revealed that collagen-lineage cells are the primary source of myofibroblasts -BLR-200 blocks myofibroblast differentiation concomitant with reduced progression toward Col8a1+ve and Sfrp2+ ve fibroblasts, populations implicated in SSc pathogenesis -BLR-200 represents a novel, translationally relevant drug candidate for SSc skin fibrosis