The gastrointestinal tract, like the urinary, respiratory, reproductive tracts and the surface of the eye, has large surface areas which are in contact with the exterior environment. The mucosal tissues in the gastrointestinal tract are exposed to large number of exogenous, water or food born microbiota. Therefore, they serve as access routes for different types of bacteria, parasites, viruses, enzymes and toxins. In order to protect the mucosal tissues against pathogens and aggressive enzymes, which are necessary in digestive processes, they are covered by a resident microbial flora and also by a viscoelastic adherent mucous gel layer. The mucus layer acts as the first line of defense against threats and also as a positive environment for beneficial endogenous microbiota adapted for symbiotic living. The quantity and quality of mucus layers varies throughout the gastrointestinal tube and is often changed and disrupted during the occurrence disease. A disturbed mucus layer in the intestine can result in changes in the whole organism, such as: impaired immunity, loss of weight and weak food conversion, which is important, especially in food animals. That is why several researchers have focused on these changes, both in humans and other animals, to find out methods and countermeasures, which will facilitate the best protection for the mucus layer in the intestine. In this review, we describe the composition and function of the mucus layer and mucins in the intestine.
1. Agawa, S., Muto, T., Morioka, Y., 1988: Mucin abnormality of colonic mucosa in ulcerative colitis associated with carcinoma and/or dysplasia. Dis. Colon Rectum, 31, 387-9.
2. Applegate, T. J., Klose, V., Steiner, T., Ganner, A., Schatzmayr, G., 2010: Probiotics and phytogenics for poultry: myth or reality. Journal of Applied Poultry Research, 19, 194-210.
3. Atuma, C., Strugala, V., Allen, A., Holm, L., 2001: The adherent gastrointestinal mucus gel layer: thickness and physical state in vivo. Am. J. Physiol. Gastrointest. Liver Physiol., 280, 922-929.
4. Caspary, W. T., 1992: Physiology and pathophysiology of intestinal absorption. Am. J. Clin. Nutr., 55, 299-308.
5. Cohen, M., Varki, N. M., Jankowski, M. D., Gagneux, P., 2012: Using fixed, frozen tissues to study natural mucin distribution.
Journal of Visualised Experiments, 67, 3928.
6. Corfield, A. P., Carroll, D., Myerscrough, N., Probert, Ch. S. J., 2001: Mucins in gastrointestinal tract in health and disease.
Frontiers in Bioscience, 6, 321-1357.
7. Ehsanullah, M., Fillipe, M. I., Gazzard, B., 1982: Mucin secretion in inflammatory bowel disease: correlation with disease activity and dysplasia. Gut, 23, 485-489.
8. Flemstrom, G., Hallgren, A., Nylander, O., Engstrand, L., Wilander, E., Allen, A., 1999: The adherent surface mucus gel restricts diffusion of macromolecules in rat duodenum in vivo. Am. J. Physiol. Gastrointest. Liver Physiol., 277, 375-382.
9. Forstner, J. F., Forstner, G. G., 1994: Gastrointestinal mucus. In Johnson, L. R. (Ed.): Physiology of the Gastrointestinal Tract, 3rd edn., Raven, New York, NY, 1255-1284.
10. Fukata, M., Abreu, M. T., 2009: Pathogen recognition receptors, cancer and inflammation in the gut. Curr. Opin. Pharmacol., 9, 680-687.
11. Goosney, D. L., Gruenheid, S., Finlay, B. B, 2000: Gut feelings: enteropathogenic E. coli (EPEC) interactions with the host. Annu. Rev. Cell Dev. Biol., 16, 173-189.
12. Gordon, J. I., Schmidt, G. H., Roth, K. A., 1992: Studies of intestinal stem cells using normal, chimeric, and transgenic mice. FASEB J., 6, 3039-3050.
13. Gum, J. R., 1989: Molecular cloning of human intestinal mucin cDNAs. Sequence analysis and evidence for genetic polymorphisms. J. Biol. Chem., 264, 6480-6487.
14. Hasnain, S. Z., Gallagher, A. L., Grencis, R. K., Thornton, D. J., 2013: A new role for mucins in immunity: Insights from gastrointestinal nematode infection. Int. J. Biochem. Cell Biol., 45, 364-374.
15. Kim, J. J., Khan, W. I., 2013: Goblet cells and mucins: Role in innate defence in enteric infections. Pathogens, 2, 55-70.
16. Linden, S. K., Sutton P., Karlsson, N. G., Korolik, V., McGuckin, M. A., 2008: Mucins in the mucosal barrier to infection, Mucosal Immunology, 1, 183-197.
17. Mack, D. R., Michail, S., Wei, S., McDougall, L., Hollingsworth, M. A., 1999: Probiotics inhibit enteropathogenic E. coli adherence in vitro by inducing intestinal mucin gene expression. Am. J. Physiol., 276, 941-950.
18. McAuley, J. L., 2007: MUC1 cell surface mucin is a critical element of the mucosal barrier to infection. J. Clin. Invest., 117, 2313-2324.
19. Mescher, A., 2013: Junqueira’s Basic Histology: Text and Atlas, 13th edn., McGraw-Hill Edition, 480 pp.
20. Mountzouris, K. C., Paraskevas, V., Tsirtsikos, P., Palamidi, I., Steiner, T., Schatzmayr, G., Fegeros, K., 2011: Assessment of a phytogenic feed additive effect on broiler growth performance, nutrient digestibility and caecal microflora composition. Animal Feed Science and Technology, 168, 223-231.
21. Neutra, M. R., Mantis, N. J., Frey, A., Giannasca, P. J., 1999: The composition and function of the M cell apical membranes: implications for microbial pathogenesis. Semin. Immunol., 11, 357-367.
22. Ogata, S., Uehara, H., Chen, A., Itzkowitz, S. H., 1992: Mucin gene expression in colonic tissues and cell lines. Cancer Res., 52, 5971-5978.
23. Roberton, A. M., Wright, D. P., 1997: Bacterial glycosulfatases and sulfomucin degradation. Can. J. Gastroenterol., 11, 361-366.
24. Smirnov, A., Tako, E., Ferket, P. R., Uni, Z., 2006: Mucin gene expression and mucin content in the chicken intestinal goblet cells are affected by in ovo feeding of carbohydrates. Poultry Sci., 85, 669-673.
25. Specian, R. D., Oliver, M. G., 1991: Functional biology of intestinal goblet cells. Am. J. Physiol., 260, 183-193.
26. Strous, G. J., Dekker, J., 1992: Mucin-type glycoproteins. Critical Reviews in Biochemistry and Molecular Biology, 27, 57-92.
27. Strugnell, R. A., Wijburg, O. L., 2010: The role of secretory antibodies in infection immunity. Nat. Rev. Microbiol., 8, 656-667.