Posted by: Kasra
I wrote recently about modulation of the host by intestinal worm Trichuris muris. Here is another brilliant study looking at the secreted proteins of this nematode and how they interact with the small intestine mucus.
Hasnain et al. published in PLoS NTD that secreted proteins of T. muris contain serine proteases that are able to degrade the mucus barrier, especially Muc2. Interestingly, they observed that the components of the mucus barrier are different during acute versus chronic infection. When worm expulsion begins in acute infection of T. muris, Muc5a is also detected in the mucus, a protein which is normally not expressed in the intestinal mucus but in the lung. Muc5a is resistant to degradation by serine proteases of the parasite and probably helps in worm expulsion. This specific host response and change in mucus does not happen during chronic infection which results in continued stay of the worm in the intestine.
Below is a schematic diagram of the structure of the mucus layer during acute and chronic infection and how Excreted Secreted Proteins (ESPs) of the parasite interact with it.
Hasnain SZ, McGuckin MA, Grencis RK, & Thornton DJ (2012). Serine Protease(s) Secreted by the Nematode Trichuris muris Degrade the Mucus Barrier. PLoS neglected tropical diseases, 6 (10) PMID: 23071854