Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
Parasitol Res. 2013 Oct;112(10):3551-5. doi: 10.1007/s00436-013-3538-5. Epub 2013 Aug 10.
Blastocystis sp. is a commonly found intestinal microorganism and was reported to cause many nonspecific gastrointestinal symptoms. Various subtypes have been previously reported, and the pathogenicity of different subtypes of Blastocystis is unclear and remains as a controversial issue. A recent study has shown that the Blastocystis antigen isolated from an unknown subtype could facilitate the proliferation of colon cancer cells. Current study was conducted to compare the effect of solubilized antigen isolated from five different subtypes of Blastocystis on colon cancer cells, HCT116. A statistically significant proliferation of these cells was observed when exposed to 1.0 μg/ml solubilized antigen isolated from subtype 3 Blastocystis (37.22%, p < 0.05). Real-time polymerase chain reaction demonstrated the upregulation of Th2 cytokines especially transforming growth factor beta in subtype 3-treated cancer cells (p < 0.01, 3.71-fold difference). Of interest, subtype 3 Blastocystis antigen also caused a significantly higher upregulation of cathepsin B (subtypes 1 and 2, p < 0.01; subtypes 4 and 5, p < 0.001; 6.71-fold difference) which lead to the postulation that it may enhance the exacerbation of existing colon cancer cells by weakening the cellular immune response. The dysregulation of IFN-γ and p53 expression also suggest Blastocystis as a proponent of carcinogenesis. Therefore, it is very likely for subtype 3 Blastocystis to have higher pathogenic potential as it caused an increased propagation of cancer cells and substantial amount of inflammatory reaction compared to other subtypes.
译文：
芽囊原虫是一种常见的肠道微生物，据报道可引起许多非特异性胃肠道症状。先前已经报道了各种亚型，不同亚型芽囊原虫的致病性尚不清楚，仍是一个有争议的问题。最近的一项研究表明，从未知亚型分离出的芽囊原虫抗原可以促进结肠癌细胞的增殖。本研究旨在比较从 5 种不同亚型的芽囊原虫中分离出的可溶性抗原对结肠癌细胞 HCT116 的影响。当用 1.0μg/ml 的 3 型芽囊原虫可溶性抗原处理时，这些细胞的增殖呈统计学意义（37.22%，p < 0.05）。实时聚合酶链反应显示，3 型处理的癌细胞中 Th2 细胞因子（特别是转化生长因子β）上调（p < 0.01，差异为 3.71 倍）。有趣的是，3 型芽囊原虫抗原还导致组织蛋白酶 B 显著上调（1 型和 2 型，p < 0.01；4 型和 5 型，p < 0.001；差异为 6.71 倍），这表明它可能通过削弱细胞免疫反应，加重现有结肠癌细胞的恶化。IFN-γ和 p53 表达的失调也表明芽囊原虫是致癌的一个因素。因此，与其他亚型相比，3 型芽囊原虫很可能具有更高的致病潜力，因为它导致癌细胞的增殖增加和大量炎症反应。
