Bacteria-Immune System Interactions in Gut –targeting on IBD

Complex microbial communities inhabit the host intestine (10 times more microbes than human cells). It coincides with the largest reservoir of immune cells in the body, resulting in intricate networking. The breakdown of this bidirectional interaction can lead to inflammatory bowel diseases (a chronic disorder comprises Crohn’s disease and ulcerative colitis, which together affect more than 3.6 million people). Here we are aiming to study the interactions between the gut microbiota, the mucosal barrier and the immune responses as one dynamic equilibrium. We focus on the resident CX3CR1+ macrophage that is central to intestinal homeostasis. By exploiting the inherent plasticity of macrophages to adjust their set points, inflammation may be controlled. Building on this, bacterial therapy is of great interest. Wild-type male mice weighing ~ 25 g (weight before treatment), were kept under standardized conditions at a temperature of 21–22°C and with 12 h light and 12 h dark cycle. The animals were divided into different groups at age between 10-12 weeks with 4-8 mice in each treatment including: control, DSS-treated, L. reuteri treated (either strain R2LC or 4659) and L. reuteri-DSS treated. L. reuteri-treated mice were given in sterile PBS containing 109 bacteria. It was given daily by gavage for 7 days for L. reuteri treatment and 14 days for L. reuteri-DSS treatment, whereas mice were given 3% DSS in the drinking water for the last 7 days of experiment. For microbial analysis, intestinal lumen content from distal ileum and distal colon were collected.