LncRNA-MIAT在LPS致COPD中的表达及在炎症浸润与肺纤维化中的机制

Expression of LncRNA-MIAT in LPS-induced COPD and its mechanism in inflammatory infiltration and pulmonary fibrosis

目的探讨长链非编码RNA MIAT(LncRNA-MIAT)在细菌脂多糖(LPS)致慢性阻塞性肺病(COPD)大鼠肺部炎症浸润与肺纤维化的相关机制。方法将大鼠分为对照组、模型组、过表达LncRNA-MIAT组、敲低LncRNA-MIAT组,采用LPS诱导构建慢性阻塞性肺病大鼠模型,苏木精-伊红染色法染色观察肺组织炎症浸润与纤维化损伤程度,实时定量聚合酶链反应(RT-qPCR)检测肺组织中LncRNA-MIAT和TOLL样受体4/核因子κB(TLR4/NF-κB)mRNA水平,蛋白质免疫印迹法检测TLR4/NF-κB蛋白表达,酶联免疫吸附法检测肺组织中白细胞介素(IL)-4、IL-6、IL-10、肿瘤坏死因子-α(TNF-α)表达水平,并分析。结果对照组肺泡和气管结构清晰,未见炎症浸润;模型组、过表达LncRNA-MIAT组、敲低LncRNA-MIAT组大鼠出现不同程度炎细胞浸润,上皮结构紊乱,存在纤维化现象;模型组大鼠肺组织中的LncRNA-MIAT和TLR4、NF-κB mRNA水平及TLR4、NF-κB蛋白相对表达量高于对照组(P<0.05);LncRNA-MIAT过表达可上调TLR4、NF-κB mRNA水平及TLR4、NF-κB蛋白相对表达量,并上调促炎因子IL-6、TNF-α的分泌,抑制抑炎因子IL-4、IL-10的分泌;LncRNA-MIAT敲低可降低TLR4、NF-κB mRNA水平及TLR4、NF-κB蛋白相对表达量,并抑制促炎因子IL-6、TNF-α的分泌,上调抑炎因子IL-4、IL-10的分泌。结论LncRNA-MIAT能够通过调控TLR4/NF-κB信号通路进而抑制COPD大鼠肺组织中炎症因子分泌,促进肺部炎症浸润与肺纤维化进展,LncRNA-MIAT在COPD的进展中扮演重要角色。

OBJECTIVE To investigate the mechanism of LncRNA-MIAT in bacterial lipopolysaccharide(LPS)-induced pulmonary inflammatory infiltration and pulmonary fibrosis in rats with chronic obstructive pulmonary disease(COPD).METHODS The rats were divided into the control group,model group,LncRNA-MIAT overexpression group,and LncRNA-MIAT knockdown group.LPS was used to induce the establishment of a rat model of chronic obstructive pulmonary disease,and HE staining was used to detect inflammatory infiltration and fibrotic injury in lung tissue.The levels of LncRNA-MIAT and TLR4/NF-κB mRNA expression in lung tissue were detected by real-time quantitative polymerase chain reaction(RT-qPCR);the protein expression of TLR4/NF-κB was detected by Western blotting,and enzyme-linked immunosorbent assay was used to detect the expression levels of interleukin(IL)-4,IL-6,IL-10 and tumor necrosis factor-α(TNF-α)in lung tissue.All the data were analyzed.RESULTS The structure of the alveoli and trachea in the control group was clear,and there was no inflammatory infiltration;the model group,the overexpression LncRNA-MIAT group,and the LncRNA-MIAT knockdown group had different degrees of inflammatory cell infiltration,disordered epithelial structure,and fibrosis.The mRNA expression levels of LncRNA-MIAT,TLR4 and NF-κB and the relative protein expression levels of TLR4 and NF-κB in rat lung tissue in the model group were higher than those in the control group(P<0.05).LncRNA-MIAT overexpression can up-regulate TLR4,NF-κB mRNA levels and the relative protein expression of TLR4 and NF-κB.It can also up-regulate the secretion of pro-inflammatory factors including IL-6 and TNF-α,and inhibit the secretion of anti-inflammatory factors of IL-4 and IL-10.LncRNA-MIAT knockdown can reduce TLR4 and NF-κB mRNA levels and the relative protein expression of TLR4 and NF-κB,promote the secretion of pro-inflammatory factors IL-6 and TNF-α,and up-regulate the secretion of anti-inflammatory factors of IL-4 and IL-10.CONCLUSION LncRNA-MIAT can inhibit the secretion of inflammatory factors in lung tissue of COPD rats by regulating the TLR4/NF-κB signaling pathway,promoting lung inflammatory infiltration and pulmonary fibrosis progression.LncRNA-MIAT plays an important role in the progression of COPD.