Sphingosine-1-Phosphate Attenuates Lung Injury Induced by Intestinal Ischemia/Reperfusion in Mice: Role of Inducible Nitric-Oxide Synthase

Multiple organ failure, including acute lung injury (ALI), is a common complication of intestinal ischemia/reperfusion (I/R) injuries and contributes to its high mortality rate. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid that enhances vascular barrier function and has anti-inflammatory effects. In the current study, we investigated the effect of S1P on lung injury induced by intestinal I/R. Mice were randomly assigned to one of the following groups: (1) sham-operated mice, (2) mice exposed to superior mesenteric artery occlusion for 45 min followed by reperfusion for 6 h, or (3) mice exposed to I/R that received S1P (100 mu g/kg, administered by peritoneal injection). S1P markedly attenuated lung injury, manifested by the improvement of histological changes and significant decreases of lung water content. Moreover, S1P markedly reduced MDA levels and MPO activity in the lung tissues, and plasma levels of proinflammatory cytokines. In addition, S1P treatment significantly suppressed NO generation accompanied by down-regulation of iNOS expression. The results indicate that S1P has a protective effect on lung injury induced by I/R, which may be related to its suppression of iNOS-induced NO generation. S1P seems to be an effective therapeutic agent for intestinal I/R-related lung injury.