The food-borne pathogen Listeria monocytogenes exploits human defences in the gut to gain entry into the body, reports a team led by Marc Lecuit at the Pasteur Institute in Paris.

Once in the intestines, the Listeria bacterium must dock to a host protein called E-cadherin to penetrate the gut wall. However, it has been unclear how Listeria gains access to E-cadherin, which normally appears only below the junctions between the cells lining the gut, not at the gut surface. The authors found that, in response to the presence of Listeria, cells in the gut called goblet cells secrete mucus to try to eliminate the bacterium. However, in so doing they reveal their E-cadherin proteins, allowing Listeria to bind to them and cross the intestinal barrier.

J. Exp. Med. 10.1084/jem.20110560 (2011)