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成分，对宿主的健康和福祉有有益的影响。选定的益生菌已被证明对人类有显著的健康益处，因此有几种特征良好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菌和双歧杆菌已被用作益生菌。本项目的目的是研究黏附乳酸杆菌和双歧杆菌是否有能力诱导肠上皮细胞中固有免疫相关基因（如粘蛋白和几种细胞因子基因）的表达。为此，以Caco-2、HT-29和Intestine-407作为人结肠细胞系。在人结肠细胞系上发现了几种罗伊氏乳杆菌、嗜酸乳杆菌群、长双歧杆菌和两歧双歧杆菌。部分黏附菌株能诱导弱粘蛋白基因表达，部分菌株能诱导β-防御素等抗菌肽基因和多种细胞因子基因表达。基因表达似乎依赖于被测细菌的粘附能力。我们还发现基因对细菌细胞的反应不同细胞系，HT-29细胞足以检测粘蛋白基因的表达，Caco-2细胞足以检测抗菌肽基因和细胞因子基因的表达。具有诱导黏液蛋白和抗菌肽基因的菌株可以作为益生菌考虑在未来的人体体内挑战研究中使用。

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.