Toll样受体4-NF-κB炎症信号通路在大鼠扩张型心肌病中的作用

Role of Toll-like receptor 4 and NF-κB inflammatory signaling pathway in dilated cardiomyopathy of rats

目的探讨Toll样受体4(TLR4)-NF-κB炎症信号通路在大鼠扩张型心肌病(DCM)中的作用。方法 42只雄性SD大鼠随机分为两组:DCM组22只,腹腔注射阿霉素1.0mg/kg,每周2次,连续6周,构建DCM模型;对照组20只,腹腔注射生理盐水1.0mg/kg。8周后行心脏彩超及心肌代谢显像检查,采用ELISA法检测血清IL-1、IL-6、TNF-α、脑钠肽(BNP)和C反应蛋白(CRP)水平,采用RT-PCR及Western blot法测定心肌组织TLR4、NF-κB mRNA及蛋白表达,分析TLR4表达与NF-κB、IL-1、IL-6、TNF-α、CRP、BNP、左心室舒张末期内径(LVEDD)及左心室射血分数(LVEF)的相关性。结果8周后检测心脏超声,DCM组大鼠LVEDD长于对照组(P<0.05),LVEF和左心室短轴收缩率低于对照组(P<0.05)。对照组大鼠心肌完整,葡萄糖代谢正常,心肌摄取^(18)氟-氟代脱氧葡萄糖(^(18) F-FDG)均匀。DCM组心肌糖代谢异常,部分心肌摄取^(18) F-FDG降低。DCM组心肌组织TLR4、NF-κB mRNA和蛋白表达较对照组升高(P<0.05)。DCM组血清IL-1、IL-6、TNF-α、CRP和BNP水平较对照组升高(P<0.05)。DCM组心肌组织TLR4与NF-κB mRNA表达呈正相关(r=0.952,P<0.01),TLR4 mRNA表达与血清IL-1、IL-6、TNF-α和CRP水平呈正相关(r=0.776、0.879、0.917和0.779,P<0.01),与BNP、LVEDD亦呈正相关(r=0.879、0.819,P<0.01),与LVEF呈负相关(r=-0.857,P<0.01)。结论TLR4-NF-κB炎症信号通路参与DCM的病理生理进程,介导心肌细胞损伤,最终导致心腔扩大,心功能减退。

Objective To investigate the role of Toll-like receptor 4 （TLR4 ） and NF-κB inflammatory signaling pathway in dilated cardiomyopathy （DCM ） of rats .Methods Forty-two male rats were randomly divided into two groups .Group A （22 rats） was injected adriamycin 1.0 mg/kg intraperitoneally twice a week for 6 weeks and group B（20 rats） was injected normal saline 1.0 mg/kg as the control .After 8 weeks ,heart Doppler ultrasound and myocardial metabolic imaging were conducted .Serum levels of IL-1 ,IL-6 ,TNF-α,brain natriuretic peptide （BNP） and C-reactive protein （CRP） were detected by ELISA .The mRNA and protein levels of TLR4 and NF-κB were examined by RT-PCR and Western blot .The relationship of TLR4 expression and NF-κB ,IL-1 ,IL-6 ,TNF-α,CRP , BNP ,left ventricular end-diastolic dimension（LVEDD） and left ventricular ejection fraction （LVEF） was analyzed .Results The LVEDD was longer and LVEF and short axis shrinkage were shorter in group A than those in group B （ P〈0 .05 ） .The myocardial structure was integrated ,glucose metabolism was normal and the uptake of 18 F-FDG was uniform in group B .The glucose metabolism was abnormal and the uptake of 18 F-FDG was lower in group A .The mRNA and protein levels of TLR4 and NF-κB and serum levels of IL-1 ,IL-6 ,TNF-α,CRP and BNP were higher in group A than those in group B（P＆lt;0 .05） .The mRNA expression of TLR4 was positively correlated with that of NF-κB ,IL-1 ,IL-6 ,TNF-α,CRP ,BNP and LVEDD ,and negatively correlated with that of LVEF （P＆lt;0 .01） .Conclusion TLR4 and NF-κB inflammation signaling pathway plays a role in the pathophysiological process of DCM and mediates myocardial cell injury ,which may be involved in the dilation of heart and heart function fails .