Intestinal helminth infection transforms the CD4+ T cell composition of the skin

Intestinal helminth parasites can alter immune responses to vaccines, other infections, allergens and autoantigens, indicating effects on host immune responses in distal barrier tissues. We herein show that C57BL/6 mice infected with the strictly intestinal nematode Heligmosomoides polygyrus have impaired capacity to initiate skin immune responses and develop skin-resident memory cells to mycobacterial antigens, both during infection and months after deworming therapy. Surprisingly, and in contrast to a previously noted loss of T cells in peripheral lymph nodes, the skin of worm-infected mice harboured higher numbers of CD4+ T cells compared to skin of uninfected controls. H. polygyrus-specific TH2 cells accumulated during infection and remained after worm expulsion. Accumulation of TH2 cells in the skin was associated with increased expression of the skin-homing chemokine receptors CCR4 and CCR10 on CD4+ T cells in blood and mesenteric lymph nodes draining intestinal tissues, indicating gut-to-skin trafficking of cells. In conclusion, we show that infection by a strictly intestinal helminth has long-term effects on immune cell composition and local immune responses to unrelated antigens in the skin, revealing a novel mechanism for T cell colonization and worm-mediated immunosuppression in this organ.