穿心莲内酯对LPS吸入性肺炎新生大鼠NLRP3、ASC及caspase-1表达的影响

The effects of andrographolide on the expressions of NLRP3,ASC and caspase-1 in neonatal rats with LPS inhalation pneumonia

目的探究穿心莲内酯对脂多糖(LPS)吸入性肺炎新生大鼠核苷酸结合域样受体蛋白3(NLRP3)、凋亡相关斑点样蛋白(ASC)及半胱氨酸天冬氨酸蛋白酶1(caspase-1)表达的影响。方法通过气管内注射2 mg/kg LPS构建新生大鼠肺炎模型,将72只新生大鼠分为6组,穿心莲内酯低、中、高剂量组新生大鼠腹腔注射穿心莲内酯10、20、30 mg·kg^-1·d^-1,地塞米松组腹腔注射地塞米松10 mg·kg^-1·d^-1,模型组、正常对照组新生大鼠腹腔注射等量生理盐水。分别在干预治疗1、3、5 d处死新生大鼠,对各组新生大鼠进行血气分析,检测各组新生大鼠肺脏湿/干重比值,检测各组新生大鼠肺损伤程度评分,苏木素-伊红(HE)染色法观察各组新生大鼠肺组织病理变化,酶联免疫吸附试验(ELISA)测定血清白细胞介素(IL)-1β、IL-6水平,Western blot检测肺组织中NLRP3、ASC、caspase-1蛋白表达水平。结果在相同时间下,与正常对照组相比,模型组新生大鼠pH值、血氧分压(PaO2)明显降低(P<0.05),血二氧化碳分压(PaCO2)值、肺脏湿/干重比值、肺组织损伤程度评分、血清IL-1β、IL-6表达水平、肺组织中NLRP3、ASC、caspase-1蛋白表达水平明显升高(P<0.05);与模型组相比,地塞米松组、穿心莲内酯低、中、高剂量组pH值、PaO2明显升高(P<0.05),PaCO2、肺脏湿/干重比值、肺组织损伤程度评分、血清IL-1β、IL-6表达水平、肺组织中NLRP3、ASC、caspase-1蛋白表达水平明显降低(P<0.05)。结论穿心莲内酯可减轻肺损伤,对肺脏组织发挥保护作用,可能与抑制NLRP3、ASC、caspase-1蛋白表达,减少促炎因子IL-1β、IL-6分泌有关。

Objective To explore the effect of andrographolide on the expressions of nucleotide-binding domain-like receptor protein 3(NLRP3),apoptosis-associated speck-like protein containing a CARD(ASC)and caspase-1 in lipopolysaccharide(LPS)induced pneumonia rats.Methods The pneumonia model of neonatal rat was established by intratracheal injection of 2 mg/kg LPS.The 72 neonatal rats were divided into six groups.Then,10,20 and 30 mg·kg^-1·d^-1 andrographolide were intraperitoneally injected in the low,medium and high dose andrographolide groups,10 mg·kg^-1·d^-1 dexamethasone was intraperitoneally injected in the dexamethasone group,and equal amount of normal saline was intraperitoneally injected in the model group and the normal control group.The neonatal rats were sacrificed on the first,the third and the fifth day.Blood gas analysis was performed on the neonatal rats in each group,the lung wet/dry weight ratio of the neonatal rats was measured,and the degree of lung injury score of neonatal rats in each group was measured.Hematoxylin-eosin(HE)staining was used to observe the pathological changes of lung tissues of neonatalrats in each group,the serum levels of interleukin(IL)-1βand IL-6 were measured by enzyme-linked immunosorbent assay(ELISA),and Western blot was used to detect the expressions of NLRP3,ASC and caspase-1 proteins in lungtissues.Results At the same time,compared with the normal control group,the pH value and blood oxygen partial pressure(PaO2)of neonatal rats in the model group were decreased significantly(P<0.05),while the blood carbon dioxide partial pressure(PaCO2),wet/dry weight ratio of lung tissues,degree of lung injury score,the serum IL-1β,IL-6 expression levels,and the expression levels of NLRP3,ASC and caspase-1 proteins in lung tissues were increased significantly(P<0.05).Compared with the model group,the pH value and PaO2 of the newborn rats in the dexamethasone group and low,medium and high dose andrographolide groups were significantly increased(P<0.05),while the PaCO2,wet/dry weight ratio of lung tissues,degree of lung injury score,the serum IL-1β,IL-6 expression levels,and the expression levels of NLRP3,ASC and caspase-1 proteins in lung tissues were decreased significantly(P<0.05).Conclusion Andrographolide can reduce lung injury and play a protective role in lung tissue,which may be related to inhibiting the expression of NLRP3,ASC and caspase-1 protein,and reducing the secretion of IL-1βand IL-6.