Lipocalin-2 protects against renal ischemia/reperfusion injury in mice through autophagy activation mediated by HIF1α and NF-κb crosstalk

Renal ischemia/reperfusion injury is a main cause of acute kidney injury (AKI) triggering an inflammatory response associated with infiltrating macrophages. Lipocalin-2 (Lcn2) levels correlate positively and protect against renal ischemia/reperfusion injury. However, the mechanisms remain unclear. The aim of study was to investigate the protective mechanisms of Lcn2 on renal ischemia/reperfusion injury. We found that Lcn2 deficiency significantly aggravated renal injury as evidenced by higher serum creatinine, more severe morphological injury, and increased tubular epithelial cell death in mice. We also observed that attenuated autophagy in Lcn2−/− mice, as autophagy markers LC3 II level was significantly decreased and p62 was increased in the Lcn2−/− mice after I/R, compared with that of wild type. Mechanistically, we found that recombinant Lcn2 attenuated hypoxia-induced apoptosis in proximal tubule epithelial cells in vitro, and downregulation of HIF-1α blunted Lcn2-induced autophagy and enhanced apoptosis. In addition, the Lcn2 attenuated NF-κb subunit p65 activation under hypoxia conditions. Thus, our findings provide a better understanding of the protective role of Lcn2 in kidney ischemia/reperfusion injury and suggest that Lcn2 may be a promising therapeutic target for treating patients with AKI.