IL-10 increases tissue injury after selective intestinal ischemia/reperfusion

Objective: This study focused on the effect of immunoregulatory cytokines on tissue injury after intestinal ischemia/reperfusion (IR). Furthermore, the role of nitric oxide, heme oxygenase-1 (HO-1) and the transcription factor NF-kappaB/Rel in the disease process was evaluated. Summary Background Data: Oxidative stress and inflammatory gene products contribute to ischemia/reperfusion injury (IRI). However, expression of stress proteins such as the inducible nitric oxide synthase (NOS-2) and HO-1 might also provide protection against IRI. Methods: IR was achieved in Lewis rats by selective clamping of the superior mesenteric artery. IL-2 or IL-10 was administered intravenously before reperfusion. Animals were killed I hour, 4 hours, and 24 hours after reperfusion. Tissue destruction was assessed by hyaluronic acid (HA) and aminoaspartate-transaminase (AST) serum levels, whereas reduction of glutathione (GSH) tissue levels was used as a marker for oxidative stress. Furthermore, the activation of NF-kappaB/Rel and the expression of NOS-2 and HO-1 were analyzed. Results: IR resulted in tissue destruction and significantly reduced GSH tissue levels in the intestines and liver. In addition, NF-kappaB/Rel activation and increased NOS-2 and HO-1 mRNA expression were detected in both organs after IR. IL-2 administration resulted in clinical improvement of the animals and was associated with increased NF-KB/Rel activation and enhanced NOS-2 and HO-1 mRNA expression. In contrast, IL-10 resulted in increased tissue destruction in both organs and sustained reduction of GSH levels in the intestines. Furthermore, IL-10 administration failed to enhance NF-kappaB/Rel activity, NOS-2 mRNA, or HO-1 mRNA expression after IR. Conclusion: IL-10 resulted in increased tissue damage after intestinal IR. This detrimental effect of IL-10 might have been the result of reduced NOS-2 and HO-1 mRNA expression. In contrast, the beneficial effect of IL-2 might have relied on increased HO-1 expression and NOS-2 activity. These controversial effects of IL-2 and IL-10 might have been mediated through transcriptional regulation of NOS-2 and HO-1 gene expression.