二肽基肽酶-4抑制剂治疗小鼠溃疡性结肠炎的机制

Mechanisms underlying therapeutic effects of DPP-4 inhibitor against ulcerative colitis in mice

目的:初步探讨二肽基肽酶-4(dipeptidylpeptidase-4,DPP-4)抑制剂治疗小鼠溃疡性结肠炎(ulcerative colitis,UC)的作用机制.方法:将30只♂Balb/c小鼠随机分为空白对照组、模型对照组、DPP-4抑制剂治疗组、柳氮磺砒啶(sulfasalazine,SASP)治疗组、DPP-4抑制剂和SASP联合治疗组.除空白对照组外,其余各组用5%葡聚糖硫酸钠(dextran sulfate sodium,DSS)诱导小鼠UC模型,空白对照组和模型对照组给予0.5%羧甲基纤维素(carboxymethyl cellulose,CMC)灌胃,DPP-4抑制剂组、SASP组、联合治疗组分别给予西格列汀、SASP及两者联合灌胃治疗,1次/d,每天记录小鼠疾病活动指数(disease activity index,DAI)值,6 d后处死小鼠,分离结肠组织,进行病理组织学观察,检测结肠组织髓过氧化物酶(myeloperoxidase,MPO)活性,采用ELISA法测定小鼠血清肿瘤坏死因子-(tumor necrosis factor-,TNF-)、白介素-10(interleukin-10,IL-10)、胰高血糖素样肽-2(glucagon-like peptid-2,GLP-2)水平.结果:与模型对照组MPO活性(1.81 U/g±0.23 U/g)相比,DPP-4抑制剂组(1.20 U/g±0.19 U/g)、SASP组(0.96 U/g±0.07 U/g)、联合治疗组(0.81 U/g±0.06 U/g)MPO活性均显著降低(P<0.01);与模型对照组血清TNF-水平(106.86 ng/L±17.02 ng/L)相比,DPP-4抑制剂组(81.24 ng/L±9.12 ng/L)、SASP组(67.86 ng/L±9.32 ng/L)、联合治疗组(53.37ng/L±9.08 ng/L)血清TNF-水平均显著降低(P<0.01);与模型对照组血清GLP-2水平(33.10pmol/L±3.22 pmol/L)相比,DPP-4抑制剂组(55.07 pmol/L±4.43 pmol/L)及联合治疗组(58.07 pmol/L±5.43 pmol/L)血清GLP-2水平显著升高(P<0.01);与模型对照组血清IL-10水平(38.20 pg/mL±2.61 pg/mL)相比,SASP组(58.10 pg/mL±2.72 pg/mL)及联合治疗组(60.68 pg/mL±2.35 pg/mL)血清IL-10水平显著升高(P<0.01).结论:DPP-4抑制剂通过抗炎和升高血清GLP-2水平,达到修复结肠炎黏膜损伤的作用,其抗炎机制与SASP作用机制不同,DPP-4抑制剂与SASP联合用药在治疗小鼠UC方面存在协同作用.

AIM： To investigate the mechanisms underlying therapeutic effects of dipeptidyl peptidase-4 （DPP-4） inhibitor against ulcerative colitis in mice. METHODS： Thirty male Balb/c mice were randomly divided into five groups： a normal group, an experimental colitis group, a DPP-4 inhibitor treatment group, a sulfasalazine （SASP） treatment group, and a DPP-4 inhibitor plus SASP treatment group. Ulcerative colitis was induced in mice with 5% dextran sulfate sodium. The normal group and experimental colitis group were intragastrically given 0.5% carboxymethyl cellulose （CMC）, and the DPP-4 inhibitor group, SASP group and DPP-4 inhibitor plus SASP group were given sitagliptin, SASP, and both the two drugs once a day, respectively. Disease activity index （DAI） was assessed every day. After six days, all mice were sacrificed. Colonic pathological changes, myeloperoxidase （MPO） activity and serum levels of tumor necrosis factor-α （TNF-α）, interleukin-10 （IL-10） and glucagon-like peptid-2 （GLP-2） were detected. RESULTS： MPO activity and serum TNF-α level in the DPP-4 inhibitor group, SASP group and the combination group were significantly lower than those in the experimental colitis group （MPO activity： 1.20 U/g ± 0.19 U/g, 0.96 U/g ± 0.07 U/g, 0.81 U/g ± 0.06 U/g vs 1.81 U/g ± 0.23 U/g, all P 〈 0.01; 81.24 ng/L ± 9.12 ng/L, 67.86 ng/L ± 9.32 ng/L, 53.37 ng/L ± 9.08 ng/L vs 106.86 ng/L ± 17.02 ng/L, all P 〈 0.01）. Serum GLP-2 level was significantly higher in the DPP-4 inhibitor group and the combination group than in the experimental group （55.07 pmol/L ± 4.43 pmol/L, 58.07 pmol/L ± 5.43 pmol/L vs 33.10 pmol/L ± 3.22 pmol/L, both P 〈 0.01）. Serum IL-10 level was significantly higher in the SASP group and the combination group than in the experimental group （58.10 pg/mL ± 2.72 pg/mL, 60.68 pg/mL ± 2.35 pg/mL vs 38.20 pg/mL ± 2.61 pg/mL, both P 〈 0.01）. CONCLUSION： DPP-4 inhibitor has a synergistic effect with SASP possibly by exerting an anti-inflammatory effect and up-regulating serum level of GLP-2.