摘要目的:探讨尼古丁在脂多糖(LPS)诱导的急性肺损伤炎症反应中的作用及机制。方法:本研究为实验研究。动物实验部分，应用LPS构建急性肺损伤小鼠模型，将C57BL/6J小鼠24只，按体质量排序，采用蛇形分组法分为4组，每组6只，对照组、LPS组、LPS+尼古丁组、LPS+尼古丁+3-MA组。留取肺组织行HE染色，肺泡灌洗液行酶联免疫吸附试验(ELISA)检测白细胞介素1β(IL-1β)水平。细胞实验部分，采用MH-S细胞系，分为4组，对照组、LPS组、LPS+尼古丁组、LPS+尼古丁+3-MA组，取细胞上清液行ELISA检测IL-1β水平，采用细胞裂解液提取总蛋白行蛋白免疫印迹法检测NLRP3、Pro-caspase1、Cleaved-caspase1、LC3BⅡ、LC3BⅠ、P62蛋白水平，免疫荧光检测LC3B表达，透射电镜观测自噬小体数量。结果:LPS组较对照组，肺组织出现明显炎性细胞浸润。支气管肺泡灌洗液和MH-S细胞上清液中IL-1β水平升高；LPS+尼古丁组较LPS组，肺组织炎性细胞浸润减轻，支气管肺泡灌洗液和细胞上清液中IL-1β水平降低；LPS+尼古丁+3-MA组较LPS+尼古丁组，肺组织炎性细胞浸润加重，支气管肺泡灌洗液和MH-S细胞上清液中IL-1β水平升高，差异均有统计学意义( F值分别为446.40、656.40， P值均<0.001)。蛋白免疫印迹法检测各组MH-S细胞裂解液，LPS组较对照组NLRP3、Pro-caspase1、Cleaved-caspase1表达水平升高，LPS+尼古丁组较LPS组NLRP3、Pro-caspase1、Cleaved-caspase 1表达水平下降，LPS+尼古丁+3-MA组较LPS+尼古丁组NLRP3、Pro-caspase1、Cleaved-caspase1表达水平升高，差异均有统计学意义( F值分别为180.00、301.70、105.80， P值均<0.001)。使用透射电镜观察4组MH-S细胞自噬小体，采用蛋白免疫印迹法检测4组MH-S细胞中P62及LC3BⅡ/LC3BⅠ表达显示，与对照组比较，LPS组自噬小体数量增多，P62表达水平降低，LC3BⅡ/LC3BⅠ升高；LPS+尼古丁组较LPS组自噬小体数量增多，P62表达水平降低，LC3B Ⅱ/LC3BⅠ升高，LPS+尼古丁+3-MA组较LPS+尼古丁组自噬小体数量减少，P62表达水平升高，LC3B Ⅱ/LC3BⅠ降低，差异均有统计学意义( F值分别为45.25、152.00、137.40， P值均<0.05)。 结论:尼古丁通过增强自噬减弱LPS诱导的急性肺损伤炎症反应及NLRP3炎症小体的活性。

abstractsObjective:To explore the effects and mechanism of nicotine on LPS-induced acute lung injury in mice.Methods:This is an experimental study.Mice models for acute lung injury were established by LPS in the present study.The 24 C57BL/6J mice were sorted by body weight and divided into 4 groups based on the Serpentine grouping including the control group, LPS group, LPS+ nicotine group, and LPS+ nicotine+ 3-MA group with 6 mice in each group.Lung tissue was stained with H&E, and 1interleukin-11β (IL-1β) were detected by the enzyme-linked immunosorbent assay (ELISA) in bronchoalveolar lavage fluid.MH-S cells were divided into 4 groups including the control group, LPS group, LPS+ nicotine group, LPS+ nicotine+ 3-MA group, the supernatant of cells was detected for IL-1β level by ELISA, and the total protein extracted from cell lysate was detected by Western blot for confirming NLRP3, Pro-caspase1, Cleaved-caspase1, LC3BI, LC3BII, P62 protein levels, immunofluorescence was applied to detect the expression of LC3B, and transmission electron microscopy was applied to observe the number of autophagosomes.Results:Compared with the control group, the evident inflammatory cell infiltration in the lung tissues and the increased IL-1β in bronchoalveolar lavage fluid and cell supernata were found in the LPS group.Compared with the LPS group, the less inflammatornt cell infiltration in the lung tissues and the decreased IL-1β in bronchoalveolar lavage fluid and cell supernatant were detected in the LPS+ nicotine group.Compared with the LPS+ nicotine group, the evident inflammatory cell infiltration in the lung tissues and the increased IL-1β in bronchoalveolar lavage fluid and cell supernata were found in the LPS+ nicotine+ 3-MA group.and the differences were statistically significant (The F values were 446.40 and 656.40, respectively; all P<0.001).Western blotting was applied to detect MH-S cell lysates in all groups, the expression levels of NLRP3, Pro-caspase1, and Cleaved-caspase 1 were elevated in the LPS group than the control group, which statistically reduced in the LPS+ nicotine group than the LPS group, these indexes were decidedly elevated in the LPS+ nicotine+ 3-MA group than the LPS+ nicotine group.(The F values were 180.00, 301.70, 105.80, respectively; all P<0.001).The autophagosomes of MH-S cells in the four groups was observed by the transmission electron microscope.Western blotting was applied to detect the expression of P62 and LC3BⅡ/LC3BⅠ of MH-S cells.Compared with the control group, the numbers of autophagosomes in LPS group increased, the expression level of P62 decreased, and the LC3BⅡ/LC3BⅠ increased.Compared with LPS group, the numbers of autophagosomes in LPS+ nicotine group increased, the expression level of P62 decreased, and the LC3BⅡ/LC3BⅠ increased.Compared with LPS+ nicotine group, the numbers of autophagosomes in LPS+ nicotine+ 3-MA group decreased, the expression level of P62 increased, and the LC3BⅡ/LC3BⅠ decreased, with statistically significant differences (The F values were 45.25, 152.00, 137.40, respectively; P<0.05). Conclusions:Nicotine attenuates LPS-induced acute lung injury inflammatory response by enhancing autophagy and the activity of NLRP3 inflammasome by enhancing autophagy.