Dual Phosphorylation of STAT1 at Y701/S727 by TNFα Drives AIM2-Mediated PANoptosis of Renal Tubular Epithelial Cells and Fibrotic Progression in Renal Allografts.

Renal allograft interstitial fibrosis, a key pathological feature of chronic renal allograft dysfunction (CAD), is a critical determinant of long-term graft survival. However, its underlying molecular mechanisms remain incompletely understood. This study uncovers the central role of programmed cell death, particularly the novel PANoptosis modality, in the progression of CAD. PANoptosis integrates features of pyroptosis, apoptosis, and necroptosis, but does not fit within the confines of any single pathway, with its mechanisms previously undefined. By analyzing cell death patterns in CAD tissues through single-cell sequencing and validating findings via in vivo and in vitro experiments, this work demonstrates that in the context of chronic inflammation, tumor necrosis factor-alpha (TNF-α) modulates signal transducer and activator of transcription 1 (STAT1) through dual phosphorylation. This process directly induces tyrosine 701 phosphorylation and activates serine 727 phosphorylation via the p38 MAPK pathway. Phosphorylated STAT1 subsequently upregulates the PANoptosome sensor absent in melanoma 2 (AIM2), driving PANoptosis in renal tubular epithelial cells. This mechanism further exacerbates interstitial fibrosis by promoting the paracrine secretion of interleukin-6 and transforming growth factor-beta, which induces epithelial-mesenchymal transition (EMT) in adjacent tubular cells. These findings represent the first demonstration of the TNF-α/STAT1/AIM2 axis in triggering PANoptosis and its downstream EMT-fibrosis cascade, offering novel therapeutic targets for CAD intervention.