南方医科大学学报

南方医科大学学报 ›› 2014, Vol. 34 ›› Issue (02): 174-.

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尿路致病性大肠杆菌外膜蛋白T的致病机制

屈娅荣，何肖龙，王勤，张立科，龙敏，罗军，张文炳，曹虹   

  • 出版日期:2014-02-20 发布日期:2014-02-20

Pathogenesis of uropathogenic Escherichia coli: role of outer membrane protein T and the
mechanism

  • Online:2014-02-20 Published:2014-02-20

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摘要： 目的探讨大肠杆菌外膜蛋白T（OmpT）参与尿路致病性大肠杆菌致病的机制。方法通过建立人膀胱癌移行上皮细胞模
型，检测野生株CFT073、ompT基因敲除株COTD、回补株COTD（pST）的体外黏附情况；比较野生株、敲除株和回补株对细胞外
基质的体外黏附能力；通过荧光定量PCR方法，比较ompT基因敲除以后，iha和iroN基因的mRNA表达水平；建立小鼠动物模
型，比较有无OmpT菌株所致小鼠膀胱和肾脏的细菌载量、血液菌浓度及炎症因子IL-6和IL-8的蛋白表达水平，验证OmpT的
致炎作用。结果野生株细胞黏附率为（8.81±1.13）%，敲除株为（4.62±0.39）%，敲除株的黏附率明显低于野生株（P<0.05）；野生
株的细胞外基质黏附率为（8.85±0.79）%，敲除株为（4.95±0.59）%，敲除株的黏附率明显低于野生株（P<0.05）；与敲除株比较，iha
和iroN基因在野生株中的表达水平分别是敲除株的2.1和3.8倍；野生株感染的小鼠膀胱组织中细菌载量均数为6.36±0.06，敲
除株为6.01±0.07，回补株为6.29±0.06，野生株感染的小鼠肾脏组织中细菌载量为6.25±0.05，敲除株为5.87±0.06，差异均有统计
学意义（P<0.05）；野生株和回补株所致小鼠膀胱和肾脏组织炎症中IL-6检出的阳性率分别为60%和50%，而ompT基因敲除株
则为12.5%。IL-8的表达情况同IL-6。结论初步证实OmpT通过发挥毒力因子的作用，从而影响尿路致病性大肠杆菌对宿主
细胞的黏附，其可能机制是影响细菌对细胞外基质的黏附和参与iha和iroN基因的表达并在致炎过程中发挥重要作用。

Abstract: Objective To study the role of outer membrane protein T (OmpT) in the pathogenesis of uropathogenic Escherichia.
coli. Methods In cultured human bladder epithelial cell line 5637, we examined the adhesion ability of wild-type (CFT073),
ompT gene knockout (COTD), and revertant (pST) strains of E.coli to the cells and the extracellular matrix (ECM). The
expressions of the adhesion gene iha and virulence gene iroN were detected by real-time PCR. Murine models of urinary tract
infection with the 3 strains were established to evaluate the bacterial burden of the bladder and kidney tissue and bacterial
counts in blood. We also detected the expressions of interleukin-6 (IL-6) and IL-8 in the bladder and kidney tissues of the mice.
Results The COTD strain showed a significantly lower cell adhesion rate than CFT073 strain [(4.62±0.39)% vs (8.81±1.13)%, P<
0.05] with also a lower ECM-adhesion rate [(4.95±0.59)% vs (8.85±0.79)%, P<0.05]. The mRNA expressions of iha and iroN in
CFT073 strain were 2.1 and 3.8 times that of COTD strain. In the mouse model, the mean bacterial load of CFT073 strain in the
bladder tissue was 6.36±0.06, significantly greater than that of COTD (6.01±0.07) and revertant (6.29±0.06) strains (P<0.05); the
bacterial load of CFT073 strain in the kidney tissue was also significantly higher than that of COTD strain (6.25±0.05 vs 5.87±
0.06, P<0.05). In mice infected with the wild-type, knockout, and revertant strains, the detection rates of IL-6, which were
identical to those of IL-8, in the inflammatory bladder and kidney tissues were 60%, 12.5%, and 50%, respectively. Conclusions
OmpT may regulate the expression of the adhesion gene iha and the transferrin gene iroN to affect the adhesion of
uropathogenic E.coli to host cells.