Life history adjustments to intestinal inflammation in a gut nematode.

Many parasitic nematodes establish chronic infections. This implies a finely tuned interaction with the host immune response in order to avoid infection clearance. Although a number of immune interference mechanisms have been described in nematodes, how parasites adapt to the immune environment provided by their hosts remains largely unexplored. Here, we used the gastrointestinal nematode Heligmosomoides polygyrus to investigate the plasticity of life history traits and immunomodulatory mechanisms in response to intestinal inflammation. We adopted an experimental model of induced colitis and exposed worms to intestinal inflammation at two different developmental stages (larvae and adults). We found that H. polygyrus responded to intestinal inflammation by up-regulating the expression of a candidate gene involved in the interference with the host immune response. Worms infecting mice with colitis also had better infectivity (earlier adult emergence in the intestinal lumen and higher survival) compared with worms infecting control hosts, suggesting that H. polygyrus adjusted its life history schedule in response to intestinal inflammation.