Iguchi Aya, Yoshikawa Hisao, Yamada Minoru, Kimata Isao, Arizono Naoki
Department of Biological Sciences, Nara Women's University, Japan.
Parasitol Res. 2009 Jul;105(1):135-40. doi: 10.1007/s00436-009-1373-5. Epub 2009 Mar 3.
Blastocystis hominis is a zoonotic intestinal protozoan parasite whose pathogenic potential is still controversial. The aim of the present study was to clarify the pathogenicity of Blastocystis parasites in rats. Oral inoculation with 1 x 10(5) cysts of Blastocystis sp. strain RN94-9 in rats resulted in chronic infection in the cecum at least until 4 weeks after infection. Histological examination revealed neither mucosal sloughing nor inflammatory cell infiltration but showed a slight but significant increase in goblet cell numbers in the cecal mucosa 1-3 weeks post-infection. Differential staining of acidic and neutral mucins by the alcian blue-periodic acid-Schiff method showed that the predominantly increased cells were neutral mucin(+) but not acidic mucin(+) goblet cells. Reverse transcription real-time polymerase chain reaction studies demonstrated significant upregulation of the expression of interferon-gamma, interleukin (IL)-12, and tumor necrosis factor alpha, but not IL-6 or granulocyte-macrophage colony-stimulating factor, in the cecal mucosa at 2 and/or 3 weeks post-infection. The induction of local host responses, including mild goblet cell hyperplasia, and significant upregulation of type-1 and proinflammatory cytokines, suggest that Blastocystis sp. strain RN94-9 is a weakly pathogenic organism that could elicit proinflammatory as well as protective responses in local tissues.
人芽囊原虫是一种人畜共患的肠道原生动物寄生虫，其致病潜力仍存在争议。本研究的目的是阐明芽囊原虫在大鼠中的致病性。给大鼠口服接种1×10⁵ 个芽囊原虫RN94 - 9株的包囊，导致盲肠慢性感染，至少持续到感染后4周。组织学检查未发现黏膜脱落或炎性细胞浸润，但在感染后1 - 3周，盲肠黏膜杯状细胞数量略有但显著增加。用阿尔辛蓝-过碘酸-希夫法对酸性和中性黏蛋白进行鉴别染色显示，主要增加的细胞是中性黏蛋白(+)杯状细胞，而非酸性黏蛋白(+)杯状细胞。逆转录实时聚合酶链反应研究表明，在感染后2周和/或3周，盲肠黏膜中干扰素-γ、白细胞介素(IL)-12和肿瘤坏死因子α的表达显著上调，但IL-6或粒细胞-巨噬细胞集落刺激因子的表达未上调。局部宿主反应的诱导，包括轻度杯状细胞增生以及1型和促炎细胞因子的显著上调，表明芽囊原虫RN94 - 9株是一种弱致病性生物体，可在局部组织中引发促炎反应以及保护性反应。
