Abstract P332: Role of T-Lymphocytes in the Long-Term Blood Pressure and Renal Disease Effects of Acute Renal Ischemia-Reperfusion Injury

Abstract

Epidemiological data indicates that acute kidney injury (AKI) is an independent risk factor for the development of hypertension and chronic kidney disease in patients. Previous studies demonstrated that rats develop sodium-dependent hypertension and kidney damage following experimental AKI induced by a renal ischemia-reperfusion (IR) insult; furthermore, these high salt deleterious effects could be blunted by administration of immunosuppressive agents. The present study was performed on Dahl SS (SS) rats and SS rats with a null mutation in the CD247 gene (SS-CD247) leading to depletion of T-lymphocytes in order to specifically examine the role of T cells in this response (n=5-6 rats/group). As assessed by serum creatinine (SCr) levels, no difference was observed in the initial response to IR injury between SS and SS-CD247: SCr increased from 0.44±0.03 to 2.16±0.32 mg/dl in SS rats 24 hours after an initial 30 minute period of renal ischemia and returned to control levels after 8 days of recovery. Moreover, no differences were noted in mean arterial pressure (MAP) or albumin excretion rate (UAlb) between SS and SS-CD247 after 43 days of recovery from IR injury while the rats were maintained on a low salt (0.4% NaCl) diet. When the rats were fed a 4.0% NaCl diet for two weeks, MAP and UAlb significantly increased in the sham SS to 178±9 mmHg and 189±25 mg/day, respectively; values significantly greater than observed in the sham SS-CD247 rats (148±2 mmHg and 87±17 mg/day). As expected, the SS rats recovered from IR injury demonstrated an exaggerated increase in MAP (peaking at 183±2 mmHg) and UAlb (275±54 mg/day) in response to high salt. There was no difference in the number of total CD3+ lymphocytes in the kidneys of IR and sham SS after high salt, though the ratio of CD4+/CD8+ T cells was increased in the IR group. Compared to sham CD247, an exaggerated elevation of MAP (157±9 mmHg) and UAlb (210±32 mg/day) was also observed in the SS-CD247 rats recovered from IR injury, demonstrating enhanced responsiveness following IR injury in animals lacking T cells. These data indicate that T lymphocytes amplify salt-sensitive hypertension and renal damage, but other mechanisms also mediate the salt-sensitive hypertension and renal damage that occurs in animals recovered from IR injury.