大麻素受体2在脓毒症大鼠急性肺损伤中的作用及其机制

Effect and mechanism of cannabinoid receptor 2 on acute lung injury in septic rats

目的探讨大麻素受体2(CB2R)对脓毒症大鼠急性肺损伤的作用及其机制。方法将SD大鼠随机分为对照组、模型组、CB2R激动剂(JWH133)组和CB2R拮抗剂(AM630)组。模型组腹腔注射脂多糖(LPS)构建脓毒症模型;JWH133组和AM630组在注射LPS前30 min注射JWH133和AM630。6 h后光镜和电镜下观察肺组织结构改变;检测肺组织含水率以及支气管肺泡灌洗液(BALF)中TNF-α、IL-1β的含量;实时定量PCR检测肺组织ERK1/2及NF-κB p65 mRNA的表达;Western blotting检测肺组织TNF-α、IL-1β、ERK、p-ERK、NF-κB p65、p-NF-κBp65的蛋白表达。结果与对照组比较,模型组肺泡结构破坏,大量炎症细胞浸润,超微结构破坏;肺组织含水率升高;BALF中TNF-α、IL-1β水平升高(P<0.05);肺组织ERK1/2、NF-κB p65 mRNA表达及TNF-α、IL-1β、p-ERK1/2、p-NF-κB p65蛋白表达水平升高(P<0.05)。与模型组相比,JWH133组病理改变及超微结构受损程度减轻,肺组织含水率降低、BALF中TNF-α和IL-1β含量降低(P<0.05),肺组织中ERK1/2、NF-κB p65 mRNA表达及TNF-α、IL-1β、p-ERK1/2、p-NF-κB p65蛋白表达水平降低(P<0.05);AM630组病理改变及超微结构受损程度加重,BALF中IL-1β含量升高(P<0.05),肺组织中p-ERK1/2、p-NF-κB p65蛋白表达水平升高(P<0.05)。结论激活CB2R可改善脓毒症大鼠急性肺损伤,其机制可能与调控ERK/NF-κB信号通路、抑制炎症反应有关。

Objective To investigate the effect of cannabinoid receptor 2(CB2R)on acute lung injury in rats with lipopolysaccharide(LPS)-induced sepsis and to explore the mechanisms involved.Methods Sprague-Dawley rats were randomly divided into the following four groups:control,LPS,JWH133,and AM630.The LPS group was established through an intraperitoneal injection of LPS,whereas the JWH133 group was injected intraperitoneally with the CB2R agonist JWH133,and the AM630 group was pretreated with the CB2R selective antagonist AM63030 minutes prior to LPS administration.Pathological and ultrastructural changes were observed using light microscopy and electron microscopy.The water content in lung tissue and TNF-αand IL-1βexpression levels in bronchoalveolar lavage fluid(BALF)were measured.The mRNA expression levels of ERK1/2 and NF-κB p65 in the lung tissue were detected using RT-qPCR.Western blotting was used to determine the TNF-α,IL-1β,ERK,p-ERK,NF-κB p65,p-NF-κB p65 protein expression levels.Results As observed under the light microscope,the alveolar structure was destroyed and a large number of inflammatory cells had infiltrated the injury site in the LPS group compared with the features in the control group.Ultrastructural damage to the lung tissue was observed under the electron microscope.Additionally,the water content,ERK1/2 and NF-κB p65 mRNA levels,and TNF-α,IL-1β,p-ERK1/2,and p-NF-κB p65 protein levels in the lung tissue and TNF-αand IL-1βcontents in the BALF were significantly increased in the LPS group(P<0.05).Compared with the pathological changes and ultrastructural damage in the LPS group,those in the JHW133 group were significantly reduced;that is,the water content,ERK1/2 and NF-κB p65 mRNA levels,and TNF-α,IL-1β,p-ERK1/2,and p-NF-κB p65 protein levels in the lung tissue and TNF-αand IL-1βamounts in the BALF were decreased significantly(P<0.05).By contrast,the pathological changes and ultrastructural damage in the AM630 group were significantly increased;that is,the BALF level of IL-1βand lung tissue expression of p-ERK1/2 and p-NF-κB p65 protein were increased significantly(P<0.05).Conclusion Activation of CB2R can alleviate acute lung injury in septic rats,which it likely does through its regulation of the ERK/NF-κB signaling pathway and inhibition of the inflammatory response.