急性PM2.5暴露对C57BL/6J小鼠和酒精性脂肪肝病模型小鼠肺组织炎症的影响

Effects of acute PM2.5 exposure on lung inflammation and NLRP3 inflammasome activation in C57BL/6J mice and alcoholic fatty liver disease model mice

目的研究急性PM2.5暴露对C57BL/6J小鼠和酒精性脂肪肝病模型小鼠肺炎症和NLRP3炎性小体的影响,为防治PM2.5暴露所致急性肺损伤提供靶点。方法将40只雄性C57BL/6J小鼠随机分为对照组、PM2.5染毒组、酒精性脂肪肝病(AFLD)模型组和AFLD+PM2.5染毒组(AFLD+PM2.5)。连续8周给予小鼠Lieber-DeCarli饮食建立AFLD模型,对照组和PM2.5染毒组给予对照饮食。从第9周开始,通过气管滴注法对PM2.5组和AFLD+PM2.5组小鼠连续7 d进行PM2.5染毒;对照组和AFLD组小鼠同时气管滴注生理盐水。末次染毒结束24 h后将动物处死。测定小鼠血细胞计数水平;用HE染色法观察肺组织的组织病理学改变;用ELISA试剂盒检测3组小鼠肺泡灌洗液中白细胞介素(interleukin,IL-1β),IL-6和TNF-α水平;用实时定量PCR检测肺组织NLRP3炎性小体相关蛋白的mRNA表达水平。结果PM2.5急性暴露导致小鼠肺泡间隔增宽。与对照组相比,PM2.5染毒组和AFLD-PM2.5组小鼠血中白细胞和单核细胞百分以及肺泡灌洗液中炎性细胞因子(IL-6、IL-1β和TNF-α)含量以及肺组织NLRP3、Caspase-1和ASC的mRNA水平均显著增高(P<0.01)。此外,AFLD+PM2.5组小鼠肺泡灌洗液中的IL-1β和TNF-α水平以及肺组织NLRP3、ASC和Caspase-1的mRNA表达(P<0.05)均显著高于PM2.5染毒组。结论急性PM2.5暴露可能通过激活肺组织NLRP3炎性小体导致小鼠急性肺损伤,并且AFLD加重了PM2.5所致急性肺损伤。

Objective To observe the effects of exposure to acute levels of particulate matter(of<2.5μm;PM2.5)on lung inflammation and NLRP3 inflammasome activation in C57BL/6J mice and alcoholic fatty liver disease model mice,and to offer a target for the prevention and treatment of PM2.5 exposure-induced acute lung injury.Methods Forty male C57BL/6J mice were randomly divided into four groups:control group,PM2.5 group,alcoholic fatty liver disease(AFLD)model group,and AFLD+PM2.5 group.Mice were fed the Lieber-DeCarli diet for eight weeks to establish AFLD;meanwhile,mice in the control group and PM2.5 group were fed a control diet.From the ninth week,mice in the PM2.5 group and AFLD+PM2.5 group were exposed to ambient PM2.5 by tracheal instillation for 7 consecutive days(once daily),and mice in the control group and AFLD+PM2.5 group were instilled with saline at the same time.Animals were euthanized 24 h after the last exposure.Blood cells were measured,and pathological changes in the lung tissue were observed using hematoxylin-eosin(HE)staining.Interleukin(IL)-1β,IL-6,and TNF-αlevels in the bronchoalveolar lavage fluid(BALF)were determined using ELISA kits.The mRNA expression levels of nucleotide-binding oligomerization domain-like receptor protein(NLRP3)inflammasome-associated protein in the lung tissue were measured using real-time PCR.Results The lung septum in PM2.5-treated mice was widened compared with the control group.Mice in the PM2.5 group and the AFLD+PM2.5 group had a higher number of white blood cells and a higher percentage of monocytes(P<0.01),significantly higher levels of inflammation cytokines(IL-6,IL-1β,and TNF-α)in the BALF(P<0.01),and higher mRNA levels of NLRP3,Caspase-1,and ASC(P<0.01)in the lung tissue compared with mice in the control group.In addition,the levels of IL-1βand TNF-αin BALF and the mRNA expression of NLRP3,Caspase-1,and ASC in the lung tissue of the AFLD+PM2.5 group were significantly higher than those in the PM2.5 group(P<0.05).Conclusions Acute PM2.5 exposure may induce acute lung injury via activating the NLRP3 inflammasome in lung tissue,and AFLD aggravates PM2.5-induced acute lung injury.