Tubular TNFSF4/OX40L promotes fibrotic transition following acute kidney injury via activating GSK-3α

Acute kidney injury (AKI) often progresses to chronic kidney disease (CKD) characterized by renal fibrosis, yet the regulatory mechanisms driving this transition remain elusive. Here, it is demonstrated that tumor necrosis factor superfamily member 4 (TNFSF4/OX40L) significantly upregulates in proximal tubular cells (PTCs) from patients with CKD and in murine models of AKI-CKD transition induced by unilateral ischemia-reperfusion injury (uIRI) or repeated low-dose cisplatin. Elevated TNFSF4 levels correlates positively with the severity of tubulointerstitial injury and negatively with estimated glomerular filtration rate. Functionally, proximal tubule-specific deletion of Tnfsf4 markedly ameliorates tubular damage, renal inflammation and interstitial fibrosis in both AKI-CKD models. Furthermore, anti-TNFSF4 monoclonal antibody exerts its therapeutic effects in AKI-CKD mice suffering from uIRI. Conversely, overexpression of TNFSF4 exacerbates pro-fibrotic responses in PTCs under TGF-β1 or chronic hypoxia conditions. Mechanistically, immunoprecipitation-mass spectrometry identifies an interaction between TNFSF4 and glycogen synthase kinase-3α (GSK-3α). TNFSF4 blocks synaptotagmin-like protein 4 (SYTL4)-mediated ubiquitination of GSK-3α, prolongs its half-life, and sustains profibrotic signaling, effects reversed by GSK-3α knockdown. Collectively, these results uncover a previously unrecognized TNFSF4-GSK-3α axis as a key proximal tubule-intrinsic driver of AKI-CKD progression, and propose targeting this pathway as a promising therapeutic strategy to mitigate renal fibrosis and halt AKI-CKD transition.