人芽囊原虫感染致大鼠肠道紧密连接破坏的机制研究

目的 探讨大鼠感染人芽囊原虫后引起肠道屏障损伤的机制.方法 将30只SD大鼠随机分为对照组及感染1、3、6、9周组(感染组),每组6只.各感染组大鼠经口感染人芽囊原虫2×108个/鼠.对照组大鼠经口灌胃等体积磷酸盐缓冲液.分别于感染后1、3、6、9周收集7h大鼠尿液检测肠道通透性,随后采用颈椎脱臼法处死大鼠,取盲肠组织...

Study on the mechanisms of the intestinal tight-junction destruction caused by Blastocystis hominis infection in rats

Objective To explore the mechanism of the intestinal barrier damage caused by Blastocystis hominis infections in rats.Methods Thirty SD rats were randomly divided into the control group,and the 1-,3-,6-and 9-week-infection groups,of 6 rats in each group.Rats in each infection group were orally infected with B.hominis trophozoites at a density of 2×108 parasites per rat,and the control group was given an equal volume of phosphate buffered saline solution.The 7-hour urine samples were collected 1,3,6 and 9 weeks post-infection for the measurement of the intestinal permeability.Then,rats were sacrificed using the cervical dislocation method,and the cecum specimens were collected for the detection of the intestinal epithelial cell permeability.The expression of tight junction-related Occludin and Claudin-1 genes and apoptosis-related Bcl-2 and Bax genes was quantified in cecum epithelial cells using the real-time fluorescent quantitative PCR(qPCR)assay,and cell apoptosis was detected in the rat cecum using the TdT-mediated dUTP nick-end labeling(TUNEL)assay.Results The median urinary lactolose to mannitol ratios were 0.29,0.72,0.44,0.46 and 0.38 in the control group,and the 1-,3-,6-and 9-week-infection groups,respectively,and the difference was statistically significant(H=12.09,P<0.05).B.hominis invasion and epithelial injury were observed in intestinal epithelial cells of rats infected with B.hominisy and transmission electron microscopy displayed the destruction of tight junctions between intestinal epithelial cells.The relative expression of Occludiu,Claudiu-1,Bcl-2 and Bax genes was 1.04,0.62,0.71,0.68 and 0.96;1.03,0.61,0.63,0.76 and 0.86;1.08,0.70,0.75,0.74 and 1.03;and 1.00,1.57,1.33,1.35 and1.10 in the control group and the 1-,3-,6-and 9-week-infection groups,respectively,and all differences were statistically significant(F=2.86,2.85,3.37 and 4.45,all P values<0.05).The median number of positive staining cells were 1.00,13.00,9.00,3.50 and 1.00 in rat cecum specimens in the control group,and the 1-,3-,6-and 9-week-infection groups,respectively,and the difference was statistically significant(H=22.95,P<0.01).Conclusion B.hominis infection may cause an increase in the rat intestinal permeability through triggering the apoptosis of intestinal epithelial cells to destroy the tight junction between intestinal epithelial cells,thereby destroying the intestinal barrier function.