Macrophage AMPK activated by oxidative stress drives profibrotic crosstalk with tubular cells to accelerate renal fibrosis after ischemic and reperfusion injury.

Ischemia-reperfusion injury (IRI) is a major cause of acute kidney injury (AKI) that significantly increases the risk of progression to chronic kidney disease (CKD). Although oxidative stress has been implicated in this transition, the precise mechanisms through which it orchestrates inflammation and fibrosis during IRI-induced AKI-CKD progression remain poorly understood. In this study, we observed sustained reactive oxygen species (ROS) production in post-IRI kidneys. ROS were found to activate AMP-activated protein kinase (AMPK) in macrophages in a calcium-dependent manner. Conditional knockout of AMPKα1 in macrophages (Lyz2-Cre; Prkaa1-fl/fl mice) significantly attenuated renal fibrosis following IRI. Single-cell RNA sequencing analysis further revealed that AMPKα1 deletion reduced the accumulation of Arg1(+) MMP12(+) macrophages and diminished a profibrotic tubular epithelial cell (TEC) subpopulation marked by persistent expression of PDGFB and VCAM1. These macrophages were shown to interact with PDGFB(+) VCAM1(+) TECs. Mechanistically, macrophage-derived TWEAK signaling through its receptor Fn14 promoted PDGFB production in TECs, driving maladaptive changes and a fibrogenic phenotype. Importantly, TWEAK neutralization effectively mitigated the AKI-to-CKD transition. Together, our results identify macrophage AMPK as a key redox sensor that, upon activation by oxidative stress, initiates maladaptive macrophage-TEC crosstalk, ultimately promoting renal fibrosis and CKD progression.