Department of Thyroid Surgery, West China Hospital, Sichuan University, Chengdu, China.
Eur Rev Med Pharmacol Sci. 2019 Aug;23(15):6637-6644. doi: 10.26355/eurrev_201908_18553.
The aim of this study was to investigate the regulatory mechanism of mesalazine (MSLZ) on microRNA-21, microRNA-31 and Toll-like receptor 4/myeloid differentiation primary response 88 (TLR4/MyD88)-dependent pathway in 2,4,6-trinitrobenzene sulfonic acid (TNBS)/ethanol-induced ulcerative colitis (UC) model in mice.
The UC model was constructed by coloclysis of TNBS/ethanol in mice. 60 male mice were randomly assigned into control group, model group, MSLZ group and Azathioprine (AZA) group, with 15 mice in each. Corresponding drug or saline was i.g. injected in mice for consecutive 14 days. Pathological lesions in colon tissues were observed by hematoxylin and eosin (HE) staining under the microscope. The expression levels of microRNA-21 and microRNA-31 in mouse colon tissues were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The mRNA and protein levels of relative genes in TLR4/MyD88-dependent pathway in mouse colon tissues were detected by qRT-PCR and Western blot, respectively.
A mouse UC model was successfully constructed based on scores of DAI, colonic damage and pathological lesions under the microscope. MSLZ markedly improved clinical symptoms and mucosal healing. Meanwhile, the protective effect of MSLZ was similar or even stronger than that of AZA. The expression levels of microRNA-21 and microRNA-31 in mouse colon tissues in the model group were significantly higher than those of the control group (p<0.01). Compared with the model group, both MSLZ and AZA treatment could remarkably inhibit the expressions of microRNA-21 and microRNA-31 (p<0.01). The mRNA and protein levels of relative genes in TLR4/MyD88-dependent pathway in mouse colon tissues were markedly upregulated in the model group when compared with those of the control group. The inhibitory effect of MSLZ on the expressions of upstream factors in TLR4/MyD88-dependent pathway (including TLR4, MyD88, TRAF-6 and NF-κB) was slightly stronger than AZA, which was weaker in inhibiting downstream factors (including TNF-α and IL-1β). However, no significant difference in the inhibition of TLR4/MyD88-dependent pathway was found between MSLZ and AZA (p>0.05).
In the TNBS/ethanol-induced UC mouse model, MSLZ could inhibit the expressions of microRNA-21 and microRNA-31 in colon tissues. Furthermore, MSLZ also inhibited the release of inflammatory factors by inhibiting the TLR4/MyD88-dependent pathway in UC mice.
本研究旨在探讨美沙拉嗪（MSLZ）对 2,4,6-三硝基苯磺酸（TNBS）/乙醇诱导的溃疡性结肠炎（UC）模型小鼠中 microRNA-21、microRNA-31 和 Toll 样受体 4/髓样分化初级反应 88（TLR4/MyD88）-依赖性通路的调节机制。
通过 TNBS/乙醇在小鼠中结肠内给药构建 UC 模型。60 只雄性小鼠随机分为对照组、模型组、MSLZ 组和硫唑嘌呤（AZA）组，每组 15 只。连续 14 天对小鼠进行相应的药物或生理盐水灌胃。通过显微镜下苏木精和伊红（HE）染色观察结肠组织的病理损伤。通过定量实时聚合酶链反应（qRT-PCR）检测小鼠结肠组织中 microRNA-21 和 microRNA-31 的表达水平。通过 qRT-PCR 和 Western blot 分别检测小鼠结肠组织中 TLR4/MyD88 依赖性通路相关基因的 mRNA 和蛋白水平。
根据 DAI、结肠损伤和显微镜下病理损伤评分，成功构建了 UC 小鼠模型。MSLZ 显著改善了临床症状和黏膜愈合。同时，MSLZ 的保护作用与 AZA 相似甚至更强。与对照组相比，模型组小鼠结肠组织中 microRNA-21 和 microRNA-31 的表达水平明显升高（p<0.01）。与模型组相比，MSLZ 和 AZA 治疗均可显著抑制 microRNA-21 和 microRNA-31 的表达（p<0.01）。与对照组相比，模型组小鼠结肠组织中 TLR4/MyD88 依赖性通路相关基因的 mRNA 和蛋白水平明显上调。MSLZ 对 TLR4/MyD88 依赖性通路上游因子（包括 TLR4、MyD88、TRAF-6 和 NF-κB）的抑制作用略强于 AZA，对下游因子（包括 TNF-α和 IL-1β）的抑制作用较弱。然而，MSLZ 与 AZA 之间在 TLR4/MyD88 依赖性通路的抑制作用无显著差异（p>0.05）。
在 TNBS/乙醇诱导的 UC 小鼠模型中，MSLZ 可抑制结肠组织中 microRNA-21 和 microRNA-31 的表达。此外，MSLZ 还通过抑制 UC 小鼠 TLR4/MyD88 依赖性通路来抑制炎症因子的释放。
