Kidney hepcidin protects the collecting duct against ferroptosis in ischemia/reperfusion-induced acute kidney injury.

Abstract

Ischemic acute kidney injury (AKI) frequently occurs in the intensive care unit. However, early diagnosis is challenging, and specific treatment strategies are still lacking. Here, our study identified endogenous hepcidin was induced with increasing severity of ischemia/reperfusion (I/R) injury mostly in collecting duct (CD) principal and intercalated cells. We employed RNA sequencing, immunoprecipitation, mass spectrometry, and gene knockdown and knockin technologies to define the role of hepcidin during I/R-induced kidney injury. Mechanically, RNA seq revealed hepcidin protected M-1 cells (murine cortical CD cell line) against ferroptosis following hypoxia/reoxygenation (H/R). Furthermore, immunoprecipitation-mass spectrometry identified hepcidin interacting with lactoferrin, consequently preserving the expression of lactoferrin following H/R which mediated the protective effect of hepcidin. Correspondingly, lactoferrin knockdown reduced the anti-ferroptotic effect of hepcidin in M-1 cells exposed to H/R revealing a novel function of hepcidin independent of the iron transporter ferroportin. In vivo, utilizing CD-specific hepcidin-knockin (HepcidinKspKI) and CD-specific hepcidin-knockdown mice (Adeno Associated Virus-Hep), we found that endogenous hepcidin protected against CD ferroptosis by preserving lactoferrin which consequently mitigated ischemic kidney injury and dysfunction, remarkedly improving the survival rate. Finally, recombinant hepcidin administration exhibited a comparable protective effect, albeit with less efficacy in reducing the mortality rate compared to conditional knockin of CD hepcidin. Collectively, our study identified an endogenous protective mechanism of injured CD cells via a hepcidin/lactoferrin/ferroptosis axis which may suggest a novel pharmacologic therapeutic for ischemic AKI.