Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Microb Pathog. 2020 Dec;149:104543. doi: 10.1016/j.micpath.2020.104543. Epub 2020 Oct 1.
The main objective of the present study was to assess and compare the safety and inhibitory efficacy of Lactobacillus acidophilus against cholera toxin and shigatoxin production by measuring CTX-B and Stx1 expression level in Caco-2 cells exposed to Vibrio cholerae (as a non-invasive small intestine pathogens and Shigella dysenteriae (as an invasive colon pathogen).
Caco-2 cells were incubated with L. acidophilus 2 h before infection by V. cholerae and S. dysenteriae. Following RNA extraction and cDNA synthesis, relative toxins mRNA levels were determined according to a comparative critical threshold (Ct) real-time PCR. L. acidophilus didn't show any cytotoxic effect on Caco-2 cells.
L. acidophilus revealed a protective effect for Caco-2 cells against S. dysenteriae and V. cholera by 51% and 57%, respectively, which was determined by MTT assay and further confirmed by morphological examination. Pretreatment of Caco-2 cells with L. acidophilus prior to exposure to V. cholerae, attenuated the CTX-B expression in V. cholerae to about 1.76 folds. Expression of Stx1 by S. dysenteriae was also down-regulated to 1.6 folds following pretreatment of Caco-2 cells by L. acidophilus. No significant difference was observed in the attenuator role of L. acidophilus in toxin production by S. dysenteriae as a colon-invasive bacterium, compared with V. cholerae, the non-invasive pathogen of small intestine.
The results of the present study suggest that L. acidophilus is safe with protective effect for human epithelial colorectal cells, and is effective enough to be applied as a supplementary treatment for attenuation of toxin production in acute infectious diarrhea caused by V. cholerae and S. dysenteriae.
本研究的主要目的是评估和比较嗜酸乳杆菌对霍乱毒素和志贺毒素产生的安全性和抑制作用，方法是测量暴露于霍乱弧菌（作为非侵袭性小肠病原体）和志贺氏痢疾杆菌（作为侵袭性结肠病原体）的 Caco-2 细胞中 CTX-B 和 Stx1 表达水平。
在感染霍乱弧菌和志贺痢疾杆菌之前，用嗜酸乳杆菌孵育 Caco-2 细胞 2 小时。提取 RNA 并合成 cDNA 后，根据比较临界阈值（Ct）实时 PCR 确定相对毒素 mRNA 水平。嗜酸乳杆菌对 Caco-2 细胞没有任何细胞毒性作用。
MTT 测定和形态学检查进一步证实，嗜酸乳杆菌对 Caco-2 细胞具有保护作用，分别使志贺痢疾杆菌和霍乱弧菌的细胞存活率提高了 51%和 57%。在暴露于霍乱弧菌之前，用嗜酸乳杆菌预处理 Caco-2 细胞，可使霍乱弧菌 CTX-B 的表达降低约 1.76 倍。用嗜酸乳杆菌预处理 Caco-2 细胞后，志贺痢疾杆菌 Stx1 的表达也下调至 1.6 倍。与非侵袭性小肠病原体霍乱弧菌相比，嗜酸乳杆菌在志贺痢疾杆菌作为侵袭性结肠病原体产生毒素方面的减弱作用没有显著差异。
本研究结果表明，嗜酸乳杆菌对人结肠上皮细胞安全，具有保护作用，可有效作为霍乱弧菌和志贺痢疾杆菌引起的急性感染性腹泻的辅助治疗方法，以减弱毒素的产生。
