芽囊原虫致病机制的研究进展

Research progress of the pathogenesis of Blastocystis

芽囊原虫(Blastocystis)是常见的寄生于人和动物肠道的原生生物,但它是否具有致病性一直存在争议。临床调查发现,芽囊原虫感染与肠易激综合征(irritable bowel syndrome, IBS)、炎症性肠病(inflammatory bowel disease, IBD)以及免疫功能低下相关。芽囊原虫通过粪-口传播,主要寄居部位是盲肠和结肠,且芽囊原虫感染能引起细胞因子(IFN-γ、IL-12和TNF-α)上调及不同程度的肠道病理变化,但其致病机制尚不明确。近年来许多体外研究提出了芽囊原虫的几种致病机制,包括降解紧密连接蛋白引起肠上皮细胞通透性增加、细胞凋亡、上调肠道上皮细胞内的促炎细胞因子以及下调诱导型一氧化氮合酶(inducible nitric oxide synthase, iNOS)。本文就芽囊原虫致病机制的最新研究进行综述。

Blastocystis is a common enteric protozoan parasite of humans and many animals,but whether it is pathogenic or not is still controversial.Clinical studies show that Blastocystis is associated with the development of irritable bowel syndrome (IBS),inflammatory bowel disease (IBD) and immune dysfunction.Blastocystis is transmitted by the faecal-oral route,and it localizes mostly in the caecum and colon.In addition,Blastocystis infection may cause upregulation of cytokine (IFN-γ,IL-12 and TNF-α) expression and intestinal pathological changes with various degrees.But the pathogenesis of Blastocystis remains unclear.Recent years,many in vitro studies have proposed several pathogenic mechanisms of Blastocystis,including degradation of tight junction proteins resulting in increased intestinal permeability,apoptosis,upregulation of pro-inflammatory cytokines,and downregulation of inducible nitric oxide synthase.In this paper,we reviewed recent progress on the pathogenesis of Blastocystis.