Acute kidney injury increases morbidity and mortality and previous studies have shown that remote ischemic preconditioning (RIPC) reduces the risk of acute kidney injury after cardiac surgery. RIPC increases urinary HMGB1 (high mobility group box protein-1) levels in patients which correlates with kidney protection. Here, we show that RIPC reduces renal ischemia-reperfusion injury and improves kidney function in mice. Mechanistically, RIPC increases HMGB1 levels in the plasma and urine and HMGB1 binds to Toll-like receptor 4 (TLR4) on renal tubular epithelial cells, inducing transcriptomic modulation of renal tubular epithelial cells and providing renal protection, whereas TLR4 activation on non-renal cells was shown to contribute to renal injury. This protection is mediated by activation of induction of AMPK⍺ and NF-kB, which induces the upregulation of Sema5b that triggers a transient, protective G1 cell-cycle arrest. In cardiac surgery patients at high risk for postoperative acute kidney injury, increased HMGB1 and Sema5b levels after RIPC were associated with renal protection after surgery. The results may help to develop future clinical treatment options for acute kidney injury.
Jan Rossaint, Melanie Meersch, Katharina Thomas, Sina Mersmann, Martin Lehmann, Jennifer Skupski, Tobias Tekath, Peter Rosenberger, John A. Kellum, Hermann Pavenstädt, Alexander Zarbock