Induction of mucin gene expression by lactic acid bacteria adhering to intestinal epithelial cells

益生菌是微生物细胞制剂或微生物细胞的组分，其对宿主的健康和福祉具有有益作用。选定的益生菌已被证明对人类具有显著的健康益处，因此几种良好表征的菌株可供人类使用，以降低胃肠道感染的风险或治疗此类感染。一些乳酸菌包括乳酸杆菌和双歧杆菌已被用作益生菌。本课题的目的是研究粘附性乳酸杆菌和双歧杆菌是否具有诱导肠上皮细胞中粘蛋白和几种细胞因子基因等先天免疫相关基因表达的能力。以Caco-2、HT-29和Intestine-407作为人结肠癌细胞系，发现罗伊氏乳杆菌、嗜酸乳杆菌群、长双歧杆菌和两歧双歧杆菌等几种菌株可粘附于人结肠癌细胞系。结果表明，部分粘附菌对粘蛋白基因的诱导作用较弱，而部分粘附菌对抗菌肽基因（包括β-防御素）和多种细胞因子基因的诱导作用较强。基因表达似乎依赖于测试细菌的粘附能力。结果还发现，针对细菌细胞的基因应答与细胞系不同，即HT-29细胞足以检测粘蛋白基因的表达，而Caco-2细胞足以检测抗菌肽基因和细胞因子基因的表达。具有诱导粘蛋白和抗菌肽基因的能力的菌株可以被考虑用于未来作为益生菌在人体中的体内挑战研究。

Probiotics are microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well-being of the host. Selected probiotics have been shown to have significant health benefits for humans, and thus several well-characterized strains are available for human use to reduce the risk of gastrointestinal infections or to treat such infections. Some Lactic acid bacteria including lactobacilli and bifidobacteria have been used as probiotics. The aim of this project is to examine whether adhesive lactobacilli and bifidobacteria have an ability to induce expression of innate immunity-relating genes such as mucin and several cytokine genes in intestinal epithelial cells. For the purpose, Caco-2 as well as HT-29 and Intestine-407 were used as human colonic cell lines.Several strains of Lactobacillus reuteri, Lactobacillus acidophilus group, Bifidobacterium longum and Bifidobacterium bifidum were found to adhere to the human colonic cell lines. Some of adhesive strains were found to induce weakly mucin gene expression, while some strains strongly induced the anti-bacterial peptide gene including β-defensin and several cytokine genes. The gene expression seems to be dependent on the adhesion ability of the bacteria tested. It was also found that the gene response against bacterial cells was different from cell lines, i.e. HT-29 cells were adequate to examine the expression of mucin gene while Caco-2 cells were adequate to examine the expression of the anti-bacterial peptide gene and cytokine genes. The strains having the ability to induce mucin and anti-bacterial peptide genes can be considered for future in vivo challenge studies in human as probiotics.