Wilms’ tumor 1 impairs apoptotic clearance of fibroblasts in distal fibrotic lung lesions

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease characterized by impaired fibroblast clearance, accumulation, and excessive extracellular matrix (ECM) protein production. Wilms' Tumor 1 (WT1), a transcription factor, is selectively upregulated in IPF fibroblasts. However, the mechanisms by which WT1 contributes to fibroblast accumulation and ECM production remain unknown. Here, we investigated the heterogeneity of WT1-expressing fibroblasts using single-nucleus RNA sequencing on the distal lung tissues of IPF patients and healthy controls. WT1 was selectively upregulated in a subset of IPF fibroblasts that co-expressed several pro-survival genes. Both the loss-of-function and gain-of-function studies support the idea that WT1 functions as a positive regulator of multiple pro-survival genes to impair apoptotic clearance and promote ECM production. In support, fibroblast-specific overexpression of WT1 augmented fibroproliferation, myofibroblast accumulation, and ECM production during bleomycin-induced pulmonary fibrosis in both young and old mice. Together, these findings identify WT1 as a potential therapeutic target to attenuate fibroblast expansion, and ECM production in the distal areas of fibrosing lungs. snRNA-Seq was performed on human lung tissue samples retreived to characterize all cell populations for the first time with nuclear RNA. CST method was used to isolate the nuclei from tissue samples from both IPF and healthy lung tissues and were processed according to instructions provided by the instrument manufacturer.