Objective: To investigate the anti-inflammatory effect and mechanisms of interleukin-35 (IL-35) in inflammatory bowel disease.
Methods: BALB/c mice were divided into three groups with 10 mice in each group:control group, model group (oral administration of 4% glucan sodium sulfate for 7 d) and IL-35-treated group (oral administration of 4% glucan sodium sulfate for 7 d, intraperitoneal injection of 2 μg IL-35 at d2-5). Disease activity index (DAI) was scored every day. After 7 d, the mice were sacrificed, and the serum and intestinal tissue samples were collected. The gross morphology of the colon was observed; HE staining was used to observe the pathological changes of colon tissue; flow cytometry was employed to detect the change of macrophage polarization ratio in colon tissue; the mRNA expression levels of cytokines IL-6, TNF-α, IFN-γ, IL-10 and SHIP1 in colon tissue were determined by real-time quantitative RT-PCR; the expression and distribution of SHIP1 in colon tissue was measured by immunohistochemistry; Western blotting was adopted to detect the expression level of SHIP1 protein in colonic intestinal tissues of each group.
Results: The DAI scores of the mice in the model group were higher than those in the control group, while the DAI scores in the IL-35-treated group were lower than those in the model group (all P<0.01). Compared with the control group, the colon length was significantly shortened in the model group (P<0.05), while the colon length of the IL-35-treated group had an increasing trend compared with the model group, but the difference was not statistically significant (P>0.05). Compared with the model group, microscopic inflammatory infiltration score was decreased and microscopic crypt destruction and score was significantly lower in IL-35-treated group (all P<0.05). The relative expression of proinflammatory cytokines IL-6, TNF-α and IFN-γ in the colon tissue of IL-35-treated group was decreased compared with the model group, while the relative expression of IL-10 mRNA was higher than that of the model group (all P<0.05). Compared with the control group, the proportion of M1 macrophages in the model group increased (P<0.05), while the proportion of M1 macrophages in the IL-35-treated group was lower than that in the model group (P<0.05). The relative expression of SHIP1 mRNA and protein in the colon tissue of IL-35-treated group was higher than that in the model group (all P<0.05).
Conclusions: IL-35 can inhibit the polarization of M1 macrophages and regulate inflammatory cytokines to promote anti-inflammatory effect on mice with colitis.
目的: 研究IL-35在炎性肠疾病中的抗炎作用及相关机制。
方法: BALB/c雌性小鼠共30只，随机分为对照组、模型组（口服4%葡聚糖硫酸钠7 d）、IL-35组（口服4%葡聚糖硫酸钠7 d，第2~5天腹腔注射IL-35 2 μg/d），每组10只。每天对小鼠进行疾病活动指数（DAI）评分；7 d后处死小鼠，留取血清和肠道组织，观察结肠大体形态；HE染色观察各组结肠组织病理形态变化；流式细胞术检测各组结肠组织中巨噬细胞极化情况；实时定量RT-PCR检测各组结肠组织中细胞因子IL-6、TNF-α、γ干扰素（IFN-γ）、IL-10和Src同源系列2结构域的肌醇5-磷酸酶1（SHIP1）的mRNA表达量；免疫组织化学法检测各组结肠组织中SHIP1的表达及分布情况；蛋白质印迹法检测各组结肠组织中SHIP1蛋白的表达。
结果: 模型组在实验过程中DAI评分较对照组增加，而IL-35组自第4天起DAI评分较模型组减少（均 P < 0.01）；与对照组比较，模型组结肠明显缩短（ P < 0.05），而IL-35组的结肠长度长于模型组，但差异无统计学意义（ P > 0.05）；与模型组比较，IL-35组炎症细胞浸润减少、黏膜组织炎症评分和腺窝破坏组织评分较模型组减少（均 P < 0.05）；IL-35组结肠组织中促炎因子IL-6、TNF-α和IFN-γ的mRNA相对表达量较模型组减少，而抑炎因子IL-10的mRNA相对表达量较模型组增加（均 P < 0.05）；与对照组比较，模型组M1型巨噬细胞比例增加（ P < 0.05），而IL-35组M1型巨噬细胞的比例较模型组减少（ P < 0.05）；IL-35组小鼠结肠组织中SHIP1 mRNA和蛋白相对表达量均较模型组增加（均 P < 0.05）。
结论: 在炎性肠疾病中，IL-35可以通过调控SHIP1表达抑制M1型巨噬细胞极化，以及调节炎症因子的表达发挥抗炎作用。