Cell surface mucin 1 protects against gut infections

Mucins are large proteins that are secreted on the surface of the gut, and while long regarded as having a role as a barrier to mucosal infection, data to support this theory have been lacking.

In a study appearing online on July 19 in advance of publication in the August print issue of the Journal of Clinical Investigation, Michael McGuckin and colleagues from the University of Queensland, Australia, show that cell surface mucin 1 (Muc1) plays a critical role in protecting the mucosal lining of the gut from bacterial infection.

These authors orally infected mice with the bacterial pathogen Campylobacter jejuni (a common cause of diarrhea) and found that 1 week after infection this organism could be detected in the organs of the vast majority of mice lacking Muc1, but never in mice with intact Muc1. Although this organism was able to enter the gastrointestinal epithelial cells lining the gut of both Muc1-deficient and Muc1-intact mice, intestinal damage was more common in Muc1-deficient animals, and the authors determined that the prevention of the spread of infection was exclusively due to Muc1 on the surface of gut epithelial cells. This is believed to be the first study in animals to demonstrate that cell surface mucins are a critical component of mucosal defense, and the role of these proteins in epithelial infections and inflammatory disease should be further examined.