细胞焦亡在新生儿坏死性小肠结肠炎中的致病作用

Pathogenic role of cell pyroptosis in necrotizing enterocolitis in neonatal rats

目的探讨细胞焦亡是否参与新生儿坏死性小肠结肠炎(necrotizing enterocolitis,NEC)发病,并分析其可能的作用机制。方法将50只新生1 d的SD大鼠按随机数字表法分为2组(n=25):正常对照组、坏死性小肠结肠炎新生大鼠组(NEC组)。正常对照组与母鼠同笼,不予处理;NEC组采用缺氧、冷刺激及人工喂养的方式建立模型。新生鼠于第1、2、3天固定时间点测量体质量,第4天处死大鼠,HE染色观察回盲部肠组织病理学变化并评分;qPCR检测NLRP3、IL-1β、IL-18基因表达水平;Western blot检测Caspase-1表达及激活情况;ELISA检测肠组织匀浆IL-1β、IL-18水平。结果与正常对照组相比,NEC组大鼠体质量明显降低,肠上皮损伤明显;NLRP3及IL-1β、IL-18基因表达增高(分别为0.33±0.06 vs 1.11±0.12,0.40±0.15 vs 1.25±0.13,1.04±0.16 vs 2.35±0.17,P<0.05);激活的Caspase-1仅在NEC组中表达,且下游炎症因子IL-1β及IL-18水平亦高于正常对照组(分别为300.4±76.5 vs 74.4±17.5,214.4±28.1 vs 23.9±19.3,P<0.01)。结论细胞焦亡参与了NEC的发病,其具体机制可能与焦亡发生后IL-1β、IL-18的水平升高有关。

Objective To investigate whether cell pyroptosisis involved in the pathogenesis of neonatal necrotizing enterocolitis（ NEC） and explore the possible mechanism. Methods Fifty neonatal（ 1-day-old） Sprague-Dawley rats were randomly divided into control group and NEC group（ n = 25）. The rats in the control group were left with their mothers without particular treatment,and those in NEC group were subjected to gavage feeding,hypoxia and cold stress to establish models of NEC. The neonatal rats were weighed at a fixed time point of the day for 3 consecutive days. On day 4,all the rats were sacrificed by decapitation and a 2-cm segment of the proximal intestine at the ileocecal junction was harvested for histopathological evaluation. The mRNA expression levels of NLRP3,interleukin-1β（ IL-1β）,and IL-18 in the intestinal tissue were detected with quantitative real-time PCR,and the expression and activation level of caspase-1 were detected with Western blotting. Enzyme-linked immunosorbent assay was performed to detect the expression levels of IL-1β and IL-18 proteins in the intestine tissues. Results Compared with the control group,the neonatal rats in NEC group showed significantly lowered body weight and obvious intestinal injury.The intestinal tissues of the neonatal rats in NEC group showed significantly increased expressions of NLRP3,IL-1β and IL-18 at both the mRNA（ P〈0. 05） and protein（ P〈0. 01） levels as compared with those in the control group. Activated caspase-1 protein was detected only in NEC group. Conclusion Cell pyroptosis participates in the pathogenesis of neonatal intestinal injury,in which increased IL-1β and IL-18 expression following cell pyroptosis may play a role.