Lactobacillus reuteri Maintains a Functional Mucosal Barrier during DSS Treatment Despite Mucus Layer Dysfunction

Abstract

Treatment with the probiotic bacterium Lactobacillus reuteri has been shown to prevent dextran sodium sulfate (DSS)-induced colitis in rats. This is partly due to reduced P-selectin-dependent leukocyte- and platelet-endothelial cell interactions, however, the mechanism behind this protective effect is still unknown. In the present study a combination of culture dependent and molecular based T-RFLP profiling was used to investigate the influence of L. reuteri on the colonic mucosal barrier of DSS treated rats. It was first demonstrated that the two colonic mucus layers of control animals had different bacterial community composition and that fewer bacteria resided in the firmly adherent layer. During DSS induced colitis, the number of bacteria in the inner firmly adherent mucus layer increased and bacterial composition of the two layers no longer differed. In addition, induction of colitis dramatically altered the microbial composition in both firmly and loosely adherent mucus layers. Despite protecting against colitis, treatment with L. reuteri did not improve the integrity of the mucus layer or prevent distortion of the mucus microbiota caused by DSS. However, L. reuteri decreased the bacterial translocation from the intestine to mesenteric lymph nodes during DSS treatment, which might be an important part of the mechanisms by which L. reuteri ameliorates DSS induced colitis.

The structures of the colonic mucosa-associated and luminal microbial communities are distinct and differentially affected by a prolonged murine stressor

“…Probiotic Lactobacillus-mediated interventions have been shown to downregulate TNF-a in the colon, enhance gut barrier activity, and reduce overall reductions in colitis-related pathology. [46][47][48][49] Additionally, treatment with probiotic Lactobacillus reuteri in mice abrogates the stressor-induced increases in the severity of the inflammatory response to a colonic pathogen. 40 Interestingly, though previous studies have found that Lactobacillus is reduced in the stool, 18,20,21,50 this study showed a reduction in mucosal epithelium-associated Lactobacillus but not in luminal lactobacilli, implying that psychological stressor exposure can have a distinct effects upon groups of mucosal microbiota compared to their luminal counterparts.…”

Modulatory Effects of Gut Microbiota on the Central Nervous System: How Gut Could Play a Role in Neuropsychiatric Health and Diseases

“…[30][31][32][33] It has also been shown that treatment with these probiotics can enhance mucus production and consequently improve the physical barrier protecting the epithelial layer. 34,35 Products of bacterial fermentation can also play an important role in maintaining the intestinal barrier. It has been shown that short-chain fatty acids can act as trophic factors for mucosal and epithelial layers.…”

“…36,37 Impaired intestinal barrier function and consequent increased gut permeability can lead to increased translocation of gut bacteria across the intestinal wall and into the mesenteric lymphoid tissue. 34 Increased exposure of the ENS or mucosal immune cells to bacteria can provoke an immune response that can lead to release of inflammatory cytokines and activation of the vagus nerve and spinal afferent neurons. Inflammatory cytokines and the vagal system in turn can modulate the activity of the CNS and ENS.…”

Efficacy of oral administration of lactic acid bacteria isolated from cocoa in a fermented milk preparation: reduction of colitis in an experimental rat model

“…Although we observed the anti-inflammatory effects of the LAB pool in our rat model of acetic acid-induced colitis, when treating with Lactobacillus lactis, Steidler et al (2000) found no effect on dextran sodium sulfate-induced inflammation in mice or spontaneous colitis developed in IL-10-deficient mice. In contrast, Dicksved et al (2012), working with the same experimental model, found that Lactobacillus reuteri was able to maintain the barrier function of the mucosa, preventing microbial translocation, despite decreasing the mucus layer. The difference between these observations can probably be attributed to the use of different animal models and experimental settings.…”