CXCL1/CXCR2在坏死性小肠结肠炎新生大鼠肠脑组织中的表达及意义

Expression and Significance of CXCL1/CXCR2 in Intestinal and Brain Tissues of Neonatal Rats with Necrotizing Enterocolitis

目的:分析趋化因子CXCL1及其受体CXCR2在坏死性小肠结肠炎(necrotizing enterocolitis,NEC)新生Sprague-Dawley(SD)大鼠肠组织和脑组织中的表达,探讨NEC相关早产儿脑损伤发病机制,为早产儿脑损伤防治提供理论基础。方法:选取川北医学院实验动物中心购得的SPF级1日龄大鼠43只(1只死亡),随机分为实验组(21只)和对照组(21只)。构建未成熟大鼠NEC模型,即实验组采用3%葡聚糖硫酸钠盐灌胃,每天4次,持续3d,建立NEC模型;对照组用同样方法灌胃生理盐水。分别于灌胃后3h、24h、72h后采取断头法处死新生鼠(每个时间点6只),留取全脑及全肠组织,采用Western Blot法分别检测不同时间点肠组织及脑组织中CXCL1、CXCR2蛋白的含量。应用GelPro软件对Western Blot条带进行灰度分析。于灌胃后72h各组取3只做脑组织及肠组织病理切片,苏木精-伊红染色。病理组织检测行病理描述分析。结果:与对照组比较,实验组大鼠肠组织肠道肿胀,肠腔积气明显,肠壁变薄;肠组织绒毛有受损、脱落和坏死,肠腺体紊乱、缺失,黏膜下及肌层有水肿、分离,基底变薄,有炎症细胞浸润;脑组织细胞层次结构不清,室周白质多孔、疏松,胶质细胞减少。WB结果显示:与对照组相比较,实验组肠组织CXCL1水平在灌胃后3h、72h增高,差异有统计学意义(F=9.476,P<0.05),而在灌胃后24h升高不明显;对照组和实验组中肠组织CXCR2水平在灌胃后各时间点差异均无统计学意义(F=2.012,P>0.05);实验组脑组织CXCL1水平在灌胃后72h显著增高,差异有统计学意义(F=35.767,P<0.05);实验组脑组织CXCR2水平在灌胃后3h、24h、72h表达均明显增高,差异有统计学意义(F=50.083,P<0.05)。结论:CXCL1/CXCR2在NEC相关脑损伤中发挥作用,CXCL1/CXCR2可能参与了肠脑轴在传递肠道炎症对发育中大脑损伤中的发病机制。

Objective:To investigate the expression of chemokine CXCL1 and its receptor CXCR2 in the intestinal tissues and brain tissues of neonatal Sprague-Dawley rats with necrotizing enterocolitis(NEC),and to explore the pathogenesis of NEC-related preterm brain injury,providing a theoretical basis for the prevention and treatment of preterm brain injury.Methods:Forty-three SPF one-day-old rats(1 died)purchased from Experimental Animal Center of North Sichuan Medical University were selected and randomly divided into the experimental group(21 rats)and the control group(21rats).NEC model of immature rats was established,that is,the experimental group was gavaged 3%Dextran Sulfate Sodium Salt(DSS)4 times a day for 3 days.The control group was gavaged with saline in the same way.The neonatal mice(6 rats at each time point)were sacrificed by head decapitation at 3h,24h and 72h after intragastric administration.The whole brain and intestine tissues were removed and the contents of CXCL1 and CXCR2 proteins in the intestine and brain tissues were measured by Western Blot at 3h,24h and 72h after gavage,respectively.The western blot bands were analysed in grey scale using GelPro software.Three animals from each group were stained with hematoxylin-eosin at 72 h after gavage for pathological sections of brain and intestinal tissues.Pathological tissue was examined for pathological description and analysis.Results:Compared with the control group,the intestinal tissue of rats in the experimental group was swollen,gas accumulation in the intestinal lumen was obvious,and the intestinal wall was thinner.The intestinal villi were damaged,exfoliated and necrotic,the intestinal glandular body was disorganized and missing,the submucosa and muscle layer was edema and separated,the base was thinned,and inflammatory cells were infiltrated.Brain tissue cell hierarchy is not clear,periventricular white matter porous,loose,decreased glial cells.WB results showed that,compared with the control group,the intestinal CXCL1 protein content in the experimental group increased at 3h and 72h after intragastric administration,with statistical significance(F=9.476,P<0.05).There was no significant difference in the intestinal CXCR2 protein content between the control group and the experimental group at each time point after intragastric administration(F=2.012,P>0.05).Compared with the control group,the brain CXCL1 protein content in the experimental group increased at 72h after intragastric administration,and the difference was statistically significant(F=35.767,P<0.05).Compared with the control group,the expression of CXCR2 protein in the brain tissues of the experimental group increased at 3h、24h and 72h after intragastric administration,with statistical significance(F=50.083,P<0.05).Conclusion:CXCL1/CXCR2 plays an important role in NEC-associated brain injury in preterm infants.And CXCL1/CXCR2 may be involved in the pathogenesis of gut-brain axis in transmitting intestinal inflammation to developing brain injury.