Plasma and urinary cytokine homeostasis and renal dysfunction during cardiac surgery

Background Cardiac surgery induces changes in plasma cytokines, Proinflamma tory cytokines have been associated with a number of renal diseases. The pr oinflammatory cytokines interleukin 8 (IL-8), tumor necrosis factor alpha ( TNF alpha), and interleukin 1 beta (IL-1 beta) are smaller than the antiinf lammatory cytokines Interleukin 10 (IL-10), interleukin 1 receptor antagoni st (IL-1ra), and TNF soluble receptor 2 (TNFsr2), and thus undergo glomerul ar filtration more readily. Accordingly, this study investigated the relati on between plasma and urinary cytokines and proximal renal dysfunction duri ng cardiac surgery. Methods:Twenty patients undergoing coronary artery bypass grafting with car diopulmonary bypass (CPB) were studied. Blood and urine samples were analyz ed for proinflammatory and antiinflammatory cytokines, Proximal tubular dys function was measured using urinary N-acetyl-beta -D-glucosaminidase (NAG)/ creatinine and alpha (1)-microglobulin/creatinine ratios. Results: Plasma IL-8, IL-10, IL-1ra, and TNFsr2 values were significantly e levated compared with baseline. Urinary IL-1ra and TNFsr2 were significantl y elevated. Urinary NAG/creatinine and alpha (1)-microglobulin/creatinine r atios were also elevated. Plasma TNF alpha at 2 h correlated with urinary N AG/creatinine ratio at 2 and 6 h (P < 0.05) and with urinary IL-1ra at 2 h (P < 0.05), Plasma IL-8 at 2 h correlated with NAG/creatinine at 6 h (P < 0 .05). Urinary IL-1ra correlated with urinary NAG/creatinine ratio after cro ss-clamp release and 2 and 6 h after CPB (P < 0.05), Conclusions: Cardiac surgery using CPB leads to changes in plasma and urina ry cytokine homeostasis that correlate with renal proximal tubular dysfunct ion, This dysfunction may be related to the renal filtration of proinflamma tory mediators. Renal autoprotective mechanisms may involve the intrarenal generation of antiinflammatory cytokines.