Carbon monoxide-releasing molecule 2 inhibits inflammation associated with intestinal ischemia-reperfusion injury in a rat model of hemorrhagic shock

Background: Intestinal ischemia-reperfusion injury (IRI) occurs in multiple clinical settings and contributes to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS). Due to the innate inflammatory immune nature, T cells play a crucial role in the pathogenesis of IRI, which includes not only CD4 + T cells, but also CD8 + and gamma delta T cells. Carbon monoxide (CO) plays an important role in regulating CD4 + T cell responses and has been proven to be a novel therapeutic target in a variety of inflammatory disease models.Objective: This study aimed to assess whether pretreatment with carbon monoxide-releasing molecule-2 (CORM -2) could ameliorate inflammation by regulating differentiation of CD4 + T cells in intestinal mucosa of rats undergoing hemorrhagic shock.Methods: A hemorrhagic shock model was established to study intestinal IRI. Morphological changes were investigated using light microscopes. Fluorescein isothiocyanate-dextran (FITC-dextran) was used as an indicator of intestinal paracellular permeability. Transcription factors involved in differentiation of CD4 + T cells in in-testinal mucosa were detected by immunofluorescence, and the expression levels of related cytokines were determined by Western blotting.Results: The results of hematoxylin-eosin (H-E) staining and FITC-dextran intestinal paracellular permeability assay revealed that CORM-2 maintained the integrity of intestinal mucosal barrier and inhibited the changes of intestinal mucosal permeability. In addition, activation of T helper type 1 (Th1) and T helper type 17 (Th17) cells, and the increased expression levels of proinflammatory cytokines, such as interleukin-17 (IL-17) and interferon-gamma (IFN-gamma), were observed in intestinal IRI process. In contrast, pretreatment with CORM-2 weakened changes of the abovementioned observations, in which inhibited activation of Th1 and Th17 cells. However, CORM-2 did not influence differentiation of regulatory T (Treg) cells in intestinal IRI progress. Notably, CORM-2 significantly upregulated the expression level of interleukin-10 (IL-10) protein and down -regulated the expression levels of IL-17 and IFN-gamma proteins in ileal tissues of rats.Conclusion: CORM-2 possessed anti-inflammatory effects in the progress of intestinal IRI by inhibiting activation of Th1 and Th17 cells in rats undergoing hemorrhagic shock.