Repurposing zafirlukast confers renal protection in ischemia-reperfusion injury via suppressing macrophage METosis

KIRI contains two stages of ischemia and reperfusion. During ischemia stage, the activating resident macrophage to emit macrophages extracellular traps (METosis), contributing to the initial renal inflammation. In the reperfusion stage, a substantial infiltration of peripheral macrophages is accumulated at the site of kidney injury and release inflammatory cytokines through METosis. The above processes contribute to the sterile inflammatory in renal, ultimately lead to acute renal failure and even death. Importantly, we found that Zafirlukast (ZFK) could prospectively target METosis and prevent KIRI development. Tacrolimus is widely used to prevent post-transplant acute kidney injury (AKI) but causes severe toxicities (e.g., nephrotoxicity, hyperglycemia). We repurposed zafirlukast (ZFK), an FDA-approved asthma drug, to address this limitation. In a murine kidney ischemia-reperfusion injury (KIRI) model, ZFK significantly attenuated renal dysfunction, reducing serum creatinine and blood urea nitrogen (BUN) to levels comparable to tacrolimus, without inducing metabolic adverse effects. RNA sequencing revealed that ZFK recapitulated tacrolimus' anti-inflammatory gene signatures while uniquely suppressing macrophage extracellular trap formation (METosis). Mechanistically, ZFK inhibited METosis by downregulating PAD4 and CitH3 expression, confirmed by immunofluorescence and flow cytometry. Single-cell transcriptomics (Tabula Muris and Human database) identified macrophages as the primary target via CysLT1R antagonism. This study provides the first evidence that ZFK protects against KIRI by targeting METosis, a key driver of sterile inflammation. Given its established safety profile, ZFK could bypass Phase I trials, accelerating clinical translation as a safer alternative to calcineurin inhibitors. Our findings also highlight the broader potential of ZFK in METs-related diseases (e.g., sepsis, atherosclerosis) and underscore drug repurposing as a strategic approach for rapid therapeutic development. • ZFK replicates tacrolimus' renoprotection in kidney ischemia-reperfusion injury while avoiding its metabolic toxicities. • ZFK attenuates KIRI by selectively suppressing METosis via PAD4 downregulation-a pathway unexplored in renal ischemia. • ZFK's FDA approval enables rapid clinical adoption as a safer alternative to calcineurin inhibitors in transplantation.