The cells lining the gut combat worm infections by secreting an immune modulator that blocks worms from feeding on host tissues.
Fred Finkelman of the University of Cincinnati in Ohio and his colleagues injected mice with one of two nematode parasites: Heligmosomoides polygyrus (pictured) or Nippostrongylus brasiliensis. They monitored worm counts, levels of cytokines (immune modulators) and changes in the intestinal lining cells.
The authors found that the cytokines IL-4 and IL-13, known to be produced in response to worm infection, stimulate gut lining cells to secrete another cytokine called RELM-β. This interferes with worm feeding, promoting expulsion of the nematodes from the gut.