ABSTRACT
Objective:To investigate the protective effect of carbon monoxide releasing molecule 2 (CORM-2) on intestinal barrier by regulating the differentiation of T lymphocytes in rats with hemorrhagic shock.Methods:Healthy male Sprague-Dawley rats ( n=56) were randomly (random number) divided into the sham operation group, shock group, dimethyl sulfoxide (DMSO) control group, inactivated carbon monoxide release molecule-2 (iCORM-2) pretreatment group and three pretreatment CORM-2 with the doses of 2, 4 and 6 mg/kg separately. The hemorrhagic shock was induced with the use of a modified Wiggers model. Rats in the CORM-2 group and iCORM-2 group were intraperitoneally injected with CORM-2 with the doses of 2, 4 and 6 mg/kg and 6 mg/kg iCORM-2 instantly before shock induction. Rats in the DMSO group received intraperitoneal administration of 2% DMSO with the same volume of iCORM-2. Rats in the shock group and sham operation group were not pretreated before inducing shock. Mean arterial pressure of each rat was recorded at different phases after catheterization or shock. Twenty-three hours after shock induction, the permeability of intestinal barrier was measured by FITC-dextran flux, and then ileum tissues were harvested to observe histopathologic changes. Immunohistochemistry was used to detect the expression of transcription factors T-bet and Foxp3 of intestinal mucosa in rats, and the expression of interferon-γ (IFN-γ), interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) in intestinal mucosa was measured by Western blot. One-way analysis of variance or Kruskal Wallis rank sum test was used to compare the difference among groups for normal or non-normal distributed data. Results:Compared with the sham operation group, serum concentrations of FITC-dextran were significantly increased in the shock group, DMSO group and iCORM-2 group (all P<0.05). The concentrations of FITC-dextran in serum of three CORM-2 pretreatment groups pretreatment were significantly decreased compared with other groups undergoing shock (all P<0.05). Rats in the shock group, DMSO group and iCORM-2 group showed severe ileum injury. CORM-2 intervention resulted in alleviation of intestinal mucosal injury in rats with shock, and rats in groups pretreatment CORM-2 at the doses of 4 and 6 mg/kg exhibited integrity of anatomic ileac structure. Compared with the sham operation group, T-bet levels of intestinal intraepithelial lymphocytes were increased in shock group and DMSO group (all P<0.05). Compared with the shock group, levels of T-bet were decreased in intestinal epithelium of three groups pretreatment with CORM-2 at the doses of 2, 4 and 6 mg/kg (all P<0.05). Foxp3 levels in intestinal intraepithelial lymphocytes of the iCORM-2 group and two groups pretreatment with CORM-2 at the doses of 4 and 6 mg/kg were increased compared with the shock group and DMSO group (all P<0.05), but there was no significant difference among the shock group, DMSO group and group pretreatment with CORM-2 at 6 mg/kg (all P>0.05). The shock group showed increased expression of IFN-γ (all P<0.05), but unchangeable expression of IL-10 and TGF-β (all P>0.05) compared with the sham operation group. Compared with the shock group, the expression levels of IL-10 in three groups pretreatment with CORM-2 at the doses of 2, 4 and 6 mg/kg were significantly increased (all P<0.05), and the expression levels of TGF-β were increased in two groups pretreatment with CORM-2 at the doses of 4 and 6 mg/kg (all P<0.05). The expression of IFN-γ in group pretreatment with CORM-2 at 6 mg/kg was significantly decreased compared with the shock group ( P<0.05). Conclusions:CORM-2 inhibited the activation of type 1 helper T cells to decrease the expression of proinflammatory factors and upregulated the expression of anti-inflammatory factors. Thus, CORM-2 reduced gut inflammation and protected the intestinal barrier.