Effect of recombinant human insulin-like growth factor-1 on the inflammatory response to acute renal injury

Renal ischemic injury evokes an inflammatory response with increased cytokine and major histocompatibility complex (MHC) expression and a mild interstitial infiltrate. This "injury response" could contribute to the tendency of ischemically injured renal transplants to reject. The studies presented here evaluated the ability of recombinant human insulin-like growth factor-1 (rhlGF-1) given after renal injury to prevent renal inflammation. The left renal pedicle of CBA and BALB/c mice was clamped for 60 min, and rhlGF-1 (25, 50, 100 micrograms) was administered sc at 2, 24, 48, 72, and 96 h after reflow. Cytokine and MHC expression was monitored in the injured kidney, compared with the contralateral kidney. In untreated mice, a single episode of injury induced the expression of MHC mRNA and products and tumor necrosis factor-alpha (TNF-alpha) mRNA, and depressed preproepidermal growth factor (ppEGF) mRNA, for up to 5 wk. With immunohistology, epithelial Class I and II MHC expression was shown to be increased for 2 wk, and Class II positive interstitial cells were shown to be increased for up to 5 wk. The ischemically injured kidneys from mice treated with rhlGF-1 and examined at 5 days showed a dose-dependent normalization of all of the changes of the injury response. This included prevention of the increased expression of MHC and cytokines and the Class II positive interstitial cells, and restoration of ppEGF mRNA. Thus the complex and long-lasting increase in proinflammatory cytokines and MHC expression that follow renal ischemia can be interrupted by treatment with rhlGF-1 beginning 2 h after the injury. This therapy may have applications to the injury response in renal transplants.