Role of Mucin 2 Glycoprotein and L-Fucose in Interaction of Immunity and Microbiome within the Experimental Model of Inflammatory Bowel Disease

Eubacterium coprostanoligenes alleviates chemotherapy-induced intestinal mucositis by enhancing intestinal mucus barrier

Chemotherapy-induced mucositis represents a severe adverse outcome of cancer treatment, significantly curtailing the efficacy of these treatments and, in some cases, resulting in fatal consequences. Despite identifying intestinal epithelial cell damage as a key factor in chemotherapy-induced mucositis, the paucity of effective treatments for such damage is evident. In our study, we discovered that Eubacterium coprostanoligenes promotes mucin secretion by goblet cells, thereby fortifying the integrity of the intestinal mucus barrier. This enhanced barrier function serves to resist microbial invasion and subsequently reduces the inflammatory response. Importantly, this effect remains unobtrusive to the anti-tumor efficacy of chemotherapy drugs. Mechanistically, E. copr up-regulates the expression of AUF1, leading to the stabilization of Muc2 mRNA and an increase in mucin synthesis in goblet cells. An especially significant finding is that E. copr activates the AhR pathway, thereby promoting the expression of AUF1. In summary, our results strongly indicate that E. copr enhances the intestinal mucus barrier, effectively alleviating chemotherapy-induced intestinal mucositis by activating the AhR/AUF1 pathway, consequently enhancing Muc2 mRNA stability.

L-fucose reduces gut inflammation due to T-regulatory response in Muc2 null mice

Fucose, the terminal glycan of the intestinal glycoprotein Mucin2, was shown to have an anti-inflammatory effect in mouse colitis models and modulate immune response due to macrophage polarization changes. In this study we evaluated the effect of 0.05% L-fucose supplementation of drinking water on immune parameters in the intestine of homozygous mutant Muc2-/-, compared to Muc2+/+ mice. To get into innate and adaptive immunity mechanisms of gut inflammation, we tested PrkdcSCIDMuc2-/- strain, Muc2 knockout on SCID background, that is characterized by lack of lymphocytes, in comparison with PrkdcSCID mice. We evaluated intestinal cytokine profiling, macrophage and eosinophil infiltration, and expression of Nos2 and Arg1 markers of macrophage activation in all strains. Markers of Th1, Treg and Th17 cells (Tbx21, Foxp3, and Rorc expression) were evaluated in Muc2-/- and Muc2+/+ mice. Both Muc2-/- and PrkdcSCIDMuc2-/- mice demonstrated increased numbers of macrophages, eosinophils, elevated levels of TNFa, GM-CSF, and IL-10 cytokines. In Muc2-/- mice we observed a wide range of pro-inflammatory cytokines elevated, such as IFN-gamma, IL-1b, IL-12p70, IL-6, M-CSF, G-CSF, IL-17, MCP-1, RANTES, MIP1b, MIP2. Muc2-/- mice demonstrated increase of Nos2, Tbx21 and Foxp3 genes mRNA, while in PrkdcSCIDMuc2-/- mice Arg1 expression was increased. We found that in Muc2-/- mice L-fucose reduced macrophage infiltration and IL-1a, TNFa, IFNgamma, IL-6, MCP-1, RANTES, MIP1b levels, decreased Nos2 expression, and induced the expression of Treg marker Foxp3 gene. On the contrary, in PrkdcSCIDMuc2-/- mice L-fucose had no effect on macrophage and eosinophil numbers, but increased TNFa, GM-CSF, IL-12p70, IL-6, IL-15, IL-10, MCP1, G-CSF, IL-3 levels and Nos2 gene expression, and decreased Arg1 gene expression. We demonstrated that anti-inflammatory effect of L-fucose observed in Muc2-/- mice is not reproduced in PrkdcSCIDMuc2-/-, which lack lymphocytes. We conclude that activation of Treg cells is a key event that leads to resolution of inflammation upon L-fucose supplementation in Muc2-/- mice.

Molecular regulation after mucosal injury and regeneration in ulcerative colitis

Ulcerative colitis (UC) is a chronic nonspecific inflammatory disease with a complex etiology. Intestinal mucosal injury is an important pathological change in individuals with UC. Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5+) intestinal stem cells (ISCs) exhibit self-renewal and high differentiation potential and play important roles in the repair of intestinal mucosal injury. Moreover, LGR5+ ISCs are intricately regulated by both the Wnt/β-catenin and Notch signaling pathways, which jointly maintain the function of LGR5+ ISCs. Combination therapy targeting multiple signaling pathways and transplantation of LGR5+ ISCs may lead to the development of new clinical therapies for UC.