Profile of the glycolipid carbohydrate chains in the different epithelial regions of digestive tract and their involvement in synbiosis and infection of bacteria

在小鼠消化道中，糖脂在不同区域的分布存在差异，即间质区为含Forssman抗原的全球型系列糖脂，上皮区为神经节型系列糖脂。无菌条件下，小鼠十二指肠、空肠和回肠上皮中以Gg_4Cer为主，转入常规饲养条件后以IV^2Fuα-Gg_4Cer为主。而胃和结肠上皮细胞中含有GM1、focusyl GMl、Gg_4cer和IV^2Fucα-Gg_4Cer，其含量不受饲养条件的影响。通过靶向缺失Fut-1和Fut-2基因，确定了消化道中负责Gg_4Cer聚焦化的基因为Fut-2。此外，虽然fut -2缺失小鼠的胃、盲肠和结肠中完全消除了集中的糖脂，但在小肠中检测到它们，表明Fut-1基因在小肠中的替代利用。由于已知Gg_4Cer是乳杆菌的受体，因此产生了针对L. johnsonii和L. testinalis的抗体，以确定糖脂的结合能力和消化道不同区域的细菌数量。抗体可与细菌细胞壁的特壁酸和消化道的Gg_4Cer反应，提示抗Gg_4Cer抗体可能参与了人类疾病（如贝雷帽病）的发生和发展，需要谨慎应用抗体对细菌与Gg_4Cer的结合分析。

In murine digestive tract, glycolipids were differentially distributed in the different regions, i.e. the globo-series glycolipids including Forssman antigens in the mesenchymal regions and the ganglio-series glycolipids in the epithelial regions. Under germ-free condition, Gg_4Cer was the dominant glycolipid in the epithelia of duodenum, jejunum and ileum, but IV^2Fuα-Gg_4Cer became the major one after transfer of mice to the conventional breeding condition. However, the gastric and colonic epithelia contained GM1, fucosyl GMl, Gg_4cer and IV^2Fucα-Gg_4Cer, whose amounts were not affected by the breeding conditions. The gene responsible for fucosylation of Gg_4Cer in the digestive tract was characterized to be Fut-2 by targeted deletion of Fut-1 and Fut-2 genes. Also, although fucosylated glycolipids were completely eliminated from the stomach, caecum and colon of Fut-2-null mice, they were detected in the small intestine, indicating the alterative utilization of Fut-1 gene in the small intestine.Since Gg_4Cer is known to be the receptor of Lactobacillus, antibodies against L. johnsonii and L .intestinalis were generated to determine the binding ability of glycolipids and the number of bacteria in the different region of digestive tract. The antibodies reacted with teichoic acid in the cell wall of bacteria and with Gg_4Cer in the digestive tract, indicating the possible involvement of bacterial infection in the onset and progress of human disease with anti-Gg_4Cer antibodies, such as Beret disease, and that careful application of antibodies is required for the binding analysis of bacteria with Gg_4Cer.