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.