Effect Of Cigarette Smoking On NLRP3 Inflammasome Signalling Pathway In Rats

Objective:Explore the effect of cigarette smoking on NLRP3 inflammasome signalling pathway in rats,and the protective effect of melatonin.Explore the role of NLRP3 inflammasome in smoking-induced atherosclerosis.Methods:15 healthy SD male rats,aged 6-8 weeks,weight 300±10g,were randomly divided into 3 groups(n=5):C group(control group),S group(smoke group)and M group(smoke + melatonin group).S and M group were exposed to cigarette smoke at 10-12a.m.and 14-16p.m.for one week,with a total of 40 cigarette per day.M group was injected intraperitoneally with 20mg/kg of melatonin each day before the smoke exposure,while C and S group received an injection of an equivalent volume of vehicle at the same time.All groups were fed with standard diet and free intake of water.After one week,the rats were anesthetized,and abdominal aorta blood and the abdominal aorta were collected.The aorta were rapidly frozen at-80?,and the mRNA expression of NLRP3 in the aortic tissue were detected by real-time qPCR,while the expression of NLRP3,ASC,IL-1?,caspase-1 protein were detected by Western Blot.Plasma was separated from the aorta blood to determine the level of plasma IL-1?,IL-18 and MCP-1 by ELISA.Peripheral blood mononuclear cell(PBMC)was separated from the rest of the blood.The expression of NLRP3 and caspase-1 protein in PBMC were detected by Western Blot.Results:1.Plasma inflammatory cytokines level:Compared with C group,plasma level of IL-1?(p<0.001),IL-18(p<0.0001)and MCP-1(p<0.01)in S group were significantly higher.Compared with S group,plasma level of IL-1?(p<0.001)and IL-18(p<0.0001)in M group were significantly lower.2.The NLRP3 and caspase-1 expression in PBMC:Compared with C group,the expression of NLRP3 and caspase-1 in S group were significantly higher(p<0.05).There was no significant difference between M and S group.3.The NLRP3,caspase-1,ASC and IL-1? expression in aortic tissue:Compared with C group,the expression of NLRP3 and IL-1? in S group were significantly higher(p<0.05).Compared with S group,the expression of NLRP3,caspase-1 and IL-1? in M group were significantly lower(p<0.05).4.The NLRP3mRNA expression in aortic tissue:Compared with C group,the NLRP3mRNA expression in S group were significantly higher(p<0.05).Compared with S group,the NLRP3mRNA expression in M group were significantly lower(p<0.05).Conclusion:Cigarette smoking can result in elevated expression of NLRP3 inflammasome in PBMC and aortic tissue,and increased level of plasma IL-1?,IL-18 and MCP-1 in rats.Cigarette smoking might induce vascular inflammation damage and atherosclerosis by activation of NLRP3 inflammasome signalling pathway in monocyte and by promoting its recruitment.Melatonin might have protective function in the smoking-induced vascular damage by inhibiting the NLRP3 inflammasome pathway.