It is primarily made up of mucins secreted by the goblet cells. MUC2 is the main mucin expressed by the colonic epithelium. It has been demonstrated that:

• an alteration in or the absence of expression of MUC2 is associated with the development of colon carcinoma and UC.
• excessive proliferation of goblet cells has been reported during the course of parasite infections, demonstrating the role of mucus in trapping and inhibition of parasite mobility.

In an article which appeared this month in Gastroenterology, the authors describe the role of mucins in the course of enteric nematode infection by Trichuris muris in mice (Hasnain et al.).

• they observed a correlation between hyperproduction of Muc2 in the colon and expulsion of the parasite in animals resistant to infection as compared to a susceptible mouse strain.
• they also showed an increase in expression of another mucin, Muc5ac, the expression of which, under “normal” conditions, is restricted to the bronchial epithelium and the stomach. Expression of this mucin would appear to increase the barrier effect, conferring upon the mucus different rheological properties (the relationships between viscosity, plasticity and elasticity) and thus enabling more satisfactory expulsion of the parasites. These results demonstrate for the first time the protective role of the mucus barrier during parasite infection, notably due to its highly regulated physical properties.

Reference:

Hasnain, S.Z., H. Wang, J.E. Ghia, N. Haq, Y. Deng, A. Velcich, R.K. Grencis, D.J. Thornton and W.I. Khan, Mucin Gene Deficiency in Mice Impairs Host Resistance to an Enteric Parasitic Infection, Gastroenterology.