Arginase2 mediates contrast-induced acute kidney injury via facilitating nitrosative stress in tubular cells

Contrast-induced acute kidney injury(CI-AKI) is the third cause of AKI. Although tubular injury has been regarded as an important pathophysiology of CI-AKI, the underlying mechanism remains elusive. Here, we found arginase2(ARG2) accumulated in the tubules of CI-AKI mice, and was upregulated in iohexol treated kidney tubular cells and in blood samples of CI-AKI mice and patients, accompanied by increased nitrosative stress and apoptosis. However, all of the above were reversed in ARG2 knockout mice, as evidenced by the ameliorated kidney dysfunction and the tubular injury, and decreased nitrosative stress and apoptosis. Mechanistically, HO-1 upregulation could alleviate iohexol or ARG2 overexpression mediated nitrosative stress. Silencing and overexpressing ARG2 was able to upregulate and downregulate HO-1 expression, respectively, while HO-1 siRNA had no effect on ARG2 expression, indicating that ARG2 might inhibit HO-1 expression at the transcriptional level, which facilitated nitrosative stress during CI-AKI. Additionally, CREB1, a transcription factor, bound to the promoter region of ARG2 and stimulated its transcription. Similar findings were yielded in cisplatin- or vancomycin-induced AKI models. Taken together, ARG2 is a crucial target of CI-AKI, and activating CREB1/ARG2/HO-1 axis can mediate tubular injury by promoting nitrosative stress, highlighting potential therapeutic strategy for treating CI-AKI.