NLRP3的过度激活与ARDS和损伤性机械通气诱导的肺损伤的关系

Overactivation of nucleotide-binding oligomerization domain-like receptor protein 3 is involved in lung injury induced by acute respiratory distress syndrome and injurious mechanical ventilation

目的探讨核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)炎症小体是否参与急性呼吸窘迫综合征(ARDS)和损伤性机械通气诱导的肺损伤。方法10只SD大鼠按随机数字表法分为生理盐水组(NS组,n=5)和油酸组(OA组,n=5),NS组和OA组分别经颈静脉注射0.1 mL/kg的NS和OA。2 h后通过氧合指数,肺损伤评分,肺湿/干重比(W/D),确定ARDS模型制备成功。另取40只雄性SD大鼠分为对照组(n=10),OA组(n=30)。麻醉后2 h后按通气方式不同,OA组分为ARDS组,小潮气量组(Vt=6 mL/kg)、损伤性通气组(Vt=20 mL/kg),每组10只。对照组和ARDS组保持自主呼吸,后两组给予机械通气。分别在麻醉后2、3、4、5、6 h采集颈动脉血行血气分析,6 h后测定W/D和肺损伤评分。RT-PCR和Western blot分别用于检测肺组织中NLRP3、半胱氨酸天冬氨酸酶(Caspase)-1、白细胞介素(IL)-1β、IL-18的mRNA及蛋白表达。结果OA组W/D、肺损伤评分高于NS组,氧合指数低于NS组(P<0.01)。ARDS组肺损伤评分和W/D低于损伤性通气组,高于小潮气量组和对照组(均P<0.001)。ARDS组pH和氧合指数低于小潮气量组,高于损伤性通气组(均P<0.05)。ARDS组动脉血二氧化碳分压(PaCO2)高于损伤性通气组,低于小潮气量组(均P<0.05)。ARDS组NLRP3、Caspase-1、IL-1β和IL-18蛋白及mRNA表达低于损伤性通气组,高于对照组(均P<0.01)。ARDS组和小潮气量组的NLRP3、Caspase-1、IL-1β和IL-18的mRNA表达比较,差异无统计学意义(均P>0.05)。结论NLRP3炎症小体过度激活参与了ARDS和损伤性机械通气诱导的肺损伤。损伤性机械通气进一步激活NLRP3炎症小体,加重肺损伤。小潮气量通气可避免NLRP3炎症小体的进一步激活。

Objective To investigate whether nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome involved in acute respiratory distress syndrome(ARDS)and lung injury induced by invasive mechanical ventilation.Methods Ten SD rats were divided into normal saline group(NS,n=5)and oleic acid group(OA,n=5)according to random number table method.NS group and OA group were given 0.1 mL/Kg of NS and OA via jugular vein,respectively.Two hours later,the ARDS model was determined to be successful by oxygenation index,lung injury score and lung wet-to-dry weight ratio(W/D).Another 40 male SD rats were divided into control group(n=10)and OA group(n=30).Two hours after anesthesia,according to different ventilation mode,OA group was divided into ARDS group,neap tide volume group(VT=6 mL/kg)and injury ventilation group(VT=20 mL/kg),with 10 rats in each group.The control group and ARDS group maintained spontaneous breathing,and the latter two groups were given mechanical ventilation.Carotid blood was collected at 2,3,4,5 h and 6 h after anesthesia for blood gas analysis,W/D and lung injury score 6 h later were measured.RT-PCR and Western blot were used to detect the mRNA and protein expressions of NLRP3,caspase-1,interleukin(IL)-1βand IL-18 in lung tissues,respectively.Results W/D and lung injury scores in OA group were higher than those in NS group,and oxygenation index was lower than that in NS group(P<0.01).The lung injury score and W/D in ARDS group were lower than those in injury-induced ventilation group,and higher than those in neap tide volume group and control group(all P<0.01).The pH and oxygenation index of ARDS group were lower than those of neap tide volume group,and higher than those of injury ventilation group(all P<0.05).Arterial partial pressure of carbon dioxide(PaCO2)in ARDS group was higher than that in injury ventilation group and lower than that in neap tidal volume group(all P<0.05).The protein and mRNA expressions of NLRP3,caspase-1,IL-1βand IL-18 in ARDS group were lower than those in injury ventilation group and higher than those in control group(all P<0.01).The mRNA expression of NLRP3,caspase-1,IL-1βand IL-18 in ARDS group and neap tidal volume group had no statistical significance(all P>0.05).Conclusion Overactivation of NLRP3 inflammasome is involved in ARDS and lung injury induced by invasive mechanical ventilation,intrusive mechanical ventilation further activates NLRP3 inflammasomes and aggravates lung injury,neap tidal ventilation prevents further activation of NLRP3 inflammasomes.