Abstract: Objective To explore the effect and mechanism of down-regulation of Toll like receptor 4(TLR4) mRNA on dendritic cell in hand-foot-mouth disease (HFMD) mice model,so as to provide reference for the prevention and treatment of HFMD. Methods Forty-five 12-day-old BALB/c suckling mice of SPF grade were selected to isolate and culture the dendritic cells.TLR4 siRNA sequence was designed and synthesized for cell infection.The suckling mice model of HFMD was established and divided into model group,down-regulated group and up-regulated group,with 15 animals in each group.Mice in the down-regulated group were intraperitoneally injected with dendritic cells that down-regulated TLR4 gene,and those in the up-regulated group were intraperitoneally injected with dendritic cells that up-regulated TLR4 gene,and the mice in the model group were intraperitoneally injected with the same amount of sterilized water.The proliferation and apoptosis of dendritic cells,the levels of serum interleukin-6 (IL-6),interleukin-12 (IL-12),tumor necrosis factor-α (TNF-α) and the expression of mitogen activated protein kinase (MAPK) pathway protein were detected and were compared among three groups. Results The proliferation rates of dendritic cells in the down-regulated group were lower than those in the up-regulated group at different time points (t=20.160,19.050,55.380,P<0.001).The apoptosis rates of dendritic cells in the down-regulated group at different time points were higher than those in the up-regulated group (t=34.740,84.570,48.020,P<0.001).The serum levels of IL-6,IL-12 and TNF-α in the down-regulated group were lower than those in the up-regulated group(t=39.330,12.660,33.690,P＜0.001).The expression levels of P-P38MAPK,p-JNK and p-ERK1/2 protein in the down-regulated group were lower than those in the up-regulated group (t=33.690,17.470,27.800,P＜0.001). Conclusion Down regulation of TLR4 mRNA can down regulating the expression of IL-6,IL-12 and TNF-α through inhibiting MAPK pathway activation and regulating pathway protein,thereby promoting the apoptosis of dendritic cells in HFMD mice.

Key words: Toll like receptor, hand foot mouth disease, dendritic cell

摘要： 目的 分析下调Toll样受体4(TLR4)mRNA对手足口病(HFMD)模型乳鼠树突状细胞的影响及作用机制,为手足口病防治提供依据。方法 选取45只SPF级12日龄BALB/c乳鼠,分离并培养树突状细胞,设计合成TLR4 siRNA序列并做细胞感染。建立手足口病模型,分为模型组、下调组、上调组各15只,下调组乳鼠腹腔注射下调TLR4基因的树突状细胞,上调组腹腔注射上调TLR4基因的树突状细胞,模型组腹腔注射等量灭菌用水。检测三组乳鼠树突状细胞增殖、凋亡,血清白介素-6(IL-6)、白介素-12(IL-12)、肿瘤坏死因子-α(TNF-α)水平及丝裂原活化蛋白激酶(MAPK)通路蛋白表达量,并进行比较。结果 下调组不同时间点树突状细胞增殖率低于上调组(t=20.160、19.050、55.380,P＜0.001);下调组不同时间点树突状细胞凋亡率高于上调组(t=34.740、84.570、48.020,P＜0.001)。下调组血清IL-6、IL-12、TNF-α水平低于上调组(t=39.330、12.660、33.690,P＜0.001)。下调组树突状细胞p-p38MAPK、p-JNK、p-ERK1/2蛋白表达量低于上调组(t=33.690、17.470、27.800,P＜0.001)。结论 下调TLR4 mRNA经抑制MAPK通路活化,调控通路蛋白,下调IL-6、IL-12、TNF-α表达,促进手足口病乳鼠树突状细胞凋亡,可以为手足口病防治提供新思路。

关键词: Toll样受体, 手足口病, 树突状细胞