Elevated Levels of Interleukin-21 in Acute Kidney Injury After Cardiopulmonary Bypass Surgery

Background: It is well-established that complications following cardiopulmonary bypass (CPB) such as acute kidney injury (AKI) lead to worse outcomes and higher mortality. Considering the importance of the post-CPB inflammatory cytokine cascade, we first assessed the post-operative interleukin (IL)-21 serum level and its association with AKI development after CPB. Methods: In this experimental before-after study, 40 patients with confirmed CPB-AKI in the Jorjani Heart Center, Bandar Abbas (from January 2017 to September 2018) were compared with 50 non-AKI patients. AKI was defined according to the Acute Kidney Injury Network. The IL-21 serum level was measured using an enzyme-linked immunosorbent assay before and 12 hours after surgery. The association between IL-21 and other variables was evaluated by correlation analyses. Results: The IL-21 serum level was significantly higher post-operation compared to its level before surgery in AKI (21.4±6.3 and 15.7±5.5, P<0.001) and non-AKI (19.1±6.4 and 13.7±6.3, P<0.001) patients, but no significant differences were observed between AKI and non-AKI patients. Age, body mass index, and creatinine were not significantly correlated with the IL-21 serum level 12 hours post operations in AKI and non-AKI subjects. Conclusion: Serum IL-21 concentrations were significantly increased in CPB patients after operation, which may contribute to the post-CPB inflammatory response syndrome. Our data did not confirm any association between increased IL-21 levels and CPB-AKI risk.