TGF-β/LAMB3 axis drives ROS-dependent renal fibrosis under hypoxic conditions.

Hypoxia is a well-established driver of renal fibrosis, but the underlying mechanisms remain unclear. In this study, we demonstrate that hypoxia-induced excessive reactive oxygen species (ROS) drive renal fibrosis, while the antioxidant N-acetylcysteine (NAC) ameliorates this pathological process. Hypoxia-induced ROS overproduction in renal tubular epithelial cells acts as the central regulator driving concurrent partial epithelial-mesenchymal transition (pEMT) and TGF-β secretion. Integrated ATAC-seq and RNA-seq analysis demonstrates that TGF-β treatment induces LAMB3 upregulation in fibroblasts through enhanced chromatin accessibility at its promoter region. Mouse model of hypoxic renal fibrosis shows marked upregulation of both TGF-β and LAMB3, implicating their involvement in fibrogenesis under hypoxic conditions. Kidney-targeted knockdown of LAMB3 significantly ameliorates hypoxia-induced renal fibrosis. TGF-β secreted by hypoxic renal tubular epithelial cells activates canonical Smad signaling in fibroblasts, which in turn upregulates LAMB3 to initiate PI3K/AKT-dependent myofibroblast differentiation. Pharmacological ROS scavenging by NAC potently disrupts this TGF-β/LAMB3 axis, improving kidney fibrosis under hypoxic conditions. Our findings reveal that TGF-β/LAMB3 axis drives ROS-dependent renal fibrosis under hypoxic conditions, identifying LAMB3 and ROS as potential therapeutic targets for fibrotic kidney diseases.