Immune regulation of intestinal glycosylation
The host immune system regulates mucin glycosylation. Cytokines such as IL-4, IL-15, and IL-22 regulate mucosal immunity by supporting mucus secretion and IL-10 by preventing MUC2 misfolding in the goblet cells (Fig. 1B)125-128. On the other hand, pro-inflammatory cytokines IL-6 and TNF-⍺ can modulate the glycosyltransferase activity leading to alterations in mucin glycosylation (Fig. 2B)129. As demonstrated in IBD patients, these alterations occur early in the disease course with hypo-sialylated glycans increased and fucosylated glycans decreased in expression129. TACAs, like T antigen and sialyl Tn (STn) antigen, were overexpressed on MUC2 in patients with CRC130.