Role of the downstream mediator of glucocorticoids, annexin A1, in the repair process of acute kidney injury

• Applicants: Professor Dr. Sebastian Bachmann; Professor Dr. Kai-Uwe Eckardt, since 11/2017
• Subject Area: Nephrology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 152203169

In acute kidney injury (AKI), endothelial and epithelial cell damage is interrelated with perturbed local renal hemodynamics and release of pro-inflammatory mediators. In response to these latter mediators, leukocytes migrate into the renal parenchyma and aggravate disease by the release of nitric oxide (NO), superoxide radicals (O2-), and prostaglandins causing oxidative/nitrosative stress and vasoconstriction and, thus, promote ongoing tissue hypoxia, and acidosis. Endogenous inhibitors of these adverse effects include resolvins, protectin D1, lipoxin 4, and members of the annexin protein superfamily. Together these inhibitors help resolve inflammation and restore renal function. The glucocorticoid-inducible protein annexin A1 may be a key component herein, but the mechanisms of its protective effects remain to be elucidated. We hypothesize that annexin A1, together with its receptor, the formyl peptide receptor 2 (FPR2), form an intrarenal paracrine system that exerts renoprotective effects in the setting of AKI, and may be targeted for organprotective therapeutic strategies. To test this, AKI will be induced in rats and annexin A1-deficient mice. Inflammatory models (anti Thy-1 nephritis in rats, anti GBM nephritis in mice) and an ischemic approach (I/RI) will be chosen. Expression of annexin A1 and FPR2 will then be studied in a time- and cell-specific manner. Renal function, hemodynamics, and morphological alterations will be determined in parallel. In a therapeutic approach we will compare the effects of glucocorticoids with those of full-length annexin A1 and the annexin A1 N-terminal fragment AC2- 26 in these models. To elucidate cellular mechanisms of protective annexin A1 effects, we set out to study its role in adaptation of cultured renal cells to hypoxia and acidosis. Taken together, these studies will advance our understanding of the recovery phase of AKI and the particular role of annexin A1. Ultimately we aim at developing novel, mechanism-based strategies for the preservation of renal function during AKI.

• DFG Programme: Research Units
• Subproject of: FOR 1368: Hemodynamic Mechanisms of Acute Kidney Injury
• Ehemaliger Antragsteller: Dr. Alexander Paliege, until 11/2017