After the body has cleared a gut bacterial infection, some intestinal tissues have long-lasting weakened immunity — partly because of gut microbes.

Infection can lead to chronic inflammatory disorders. To find possible mechanisms, Yasmine Belkaid at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, and her colleagues infected mice with a foodborne pathogen, Yersinia pseudotuberculosis, and then monitored them for up to six months. They found a variety of changes that weaken the immune system in gut tissues. For example, immune cells called dendritic cells were diverted into fat tissue away from lymph nodes, where they would normally activate the immune response. Signals from gut microbes also seemed to maintain inflammation.

The results show how frequent infections could lead to chronic disease later in life.

Cell 163, 354–366 (2015)