Mast cells activation contribute to small intestinal ischemia reperfusion induced acute lung injury in rats

BackgroundSmall intestinal ischemia-reperfusion (IIR) injury may lead to severe local and remote tissue injury, especially acute lung injury (ALI). Mast cell activation plays an important role in IIR injury. It is unknown whether IIR mediates lung injury via mast cell activation.MethodsAdult SD rats were randomized into sham operated group (S), sole IIR group (IIR) in which rats were subjected to 75 min of superior mesenteric artery occlusion followed by 4 h reperfusion, or IIR being respectively treated with the mast cell stabilizer Cromolyn Sodium (IIR + CS group), with the tryptase antagonist Protamine (IIR + P group), with the histamine receptor antagonist Ketotifen (IIR + K group), or with the mast cell degranulator Compound 48/80 (IIR + CP group). The above agents were, respectively, administrated intravenously 5 min before reperfusion. At the end of experiment, lung tissue was obtained for histologic assessment and assays for protein expressions of tryptase and mast cell protease 7(MCP7). Pulmonary mast cell number and levels of histamine, TNF-α and IL-8 were quantified.ResultsIIR resulted in lung injury evidenced as significant increases in lung histological scores (P < 0.05 IIR vs. S), accompanied with concomitant increases of mast cell counts and elevations in TNF-α and IL-8 concentrations and reductions in histamine levels (all P < 0.05 IIR vs. S). IIR also increased lung tissue tryptase and MCP7 protein expressions (all P < 0.05, IIR vs. S). Cromolyn Sodium, Ketotifen and Protamine significantly reduced whilst Compound 48/80 aggravated IIR mediated ALI and the above biochemical changes (P < 0.05).ConclusionsMast cells activation play a critical role in IIR mediated ALI.