体外发酵条件下嗜热链球菌S131对肠道健康的调控机制

Mechanistic Insights into Streptococcus thermophilus S131 Impact on Intestinal Health via in Vitro Fermentation Studies

摘要:

该研究以HT-29细胞与人体肠道菌群批量发酵模拟系统相结合，探究嗜热链球菌S131对肠道屏障的影响、拮抗致病菌造成的肠道损伤及对有益菌的增殖效果。结果表明，与对照组相比S131使HT-29细胞黏蛋白MUC2、紧密连接蛋白ZO-1、ZO-2、Claudin-1与Occludin mRNA相对表达分别提升至1.34、4.59、2.17、5.81和4.25，同时能够缓解产肠毒素性大肠杆菌（Enterotoxigenic E. coli，ETEC）对相应基因表达的抑制，各基因分别提升至1.42、6.28、3.27、5.03和4.79。S131对ETEC造成的HT-29细胞炎症因子分泌增加具有显著抑制作用，使IL-8和IL-1β分别由821.79 pg/mL和2.22 pg/mL降至573.92 pg/mL和0.29 pg/mL。S131改善了ETEC造成的上皮细胞损伤，将细胞增殖率提升至21.07%。同时S131缓解了ETEC造成的AQP-3 mRNA相对表达下调，使AQP-3基因表达提升至1.21。并且通过qPCR检测发现S131提升了体外发酵体系中柔嫩梭菌属（Faecalibacterium）和多形拟杆菌属（Bacteroides thetaiotaomicron）的相对丰度，改善了ETEC造成的乳杆菌属（Lactobacillus）、双歧杆菌属（Bifidobacterium）、多形拟杆菌和柔嫩梭菌属的降低。综上，嗜热链球菌S131可能通过增强肠道屏障、拮抗致病菌损伤和调节肠道菌群来改善肠道健康。

Abstract:

Using HT-29 cells in combination with a batch fermentation system that simulates human intestinal flora metabolism, the effects of Streptococcus thermophilus S131 on the intestinal barrier, including mitigation of pathogen-induced intestinal damage, and its role in promoting the growth of beneficial bacteria were assessed. Compared to control fermentations, cultures with S. thermophilus S131 increased mucin (MUC2) relative mRNA levels 1.34 fold, and respective tight junction protein (ZO-1, ZO-2, claudin-1, and occludin) levels 4.59, 2.17, 5.81, and 4.25 fold. Inclusion of S. thermophilus S131 also ameliorated downregulation of these genes by enterotoxigenic E. coli (ETEC), increasing respective expression levels 1.42, 6.28, 3.27, 5.03, and 4.79 fold relative to cultures exposed to ETEC alone. S. thermophilus S131 significantly suppressed ETEC-mediated increased inflammatory factor secretion by HT-29 cells, reducing IL-8 and IL-1β levels from 821.79 and 2.22 pg/mL to 573.92 and 0.29 pg/mL, respectively. It also ameliorated ETEC-induced epithelial cell damage, increasing the cell proliferation rate by 21.07%. S. thermophilus S131 also alleviated ETEC suppression of AQP-3 mRNA expression by 21%. qPCR assays revealed that S. thermophilus S131 increased the relative abundance of Faecalibacterium and Bacteroides thetaiotaomicron in our in vitro fermentation system, rescuing ETEC mediated suppression of Lactobacillus, Bifidobacterium, Bacteroides thetaiotaomicron, and Faecalibacterium. In conclusion, S. thermophilus S131 may promote intestinal health by strengthening the intestinal barrier, antagonizing pathogen-induced damage, and regulating the intestinal flora.