Mucin-2 (MUC2) belongs to the mucin family. They are high molecular weight proteins that are components of mucus and are synthesised and secreted by specialised cells of the epithelium (goblet cells, cells of mucous glands) or non mucin-secreting cells []. There are two main mucin subfamilies: secreted mucins or gel-forming mucins (MUC2, MUC5AC, MUC5B, MUC6) and membrane-bound mucins (MUC1, MUC3, MUC4, MUC12, MUC17) []. In colon epithelium, MUC2 forms a net-like disulfide-bonded polymer structure that organise the two mucus layer of colon []. The colon inner layer is adherent to intestinal epithelial cells (IECs) and does not allow bacteria to penetrate, while the outer layer is inhabited by the microbiota []. In the small intestine, MUC2 modulates inflammatory responses and delivers tolerogenic signal to antigen-sampling dendritic cells (DCs) []. It plays an important role in gut homeostasis and promotes oral tolerance [].
