Enteric tuft cells coordinate timely expulsion of the tapeworm Hymenolepis diminuta from the murine host by coordinating local but not systemic immunity.

Recognizing that enteric tuft cells can signal the presence of nematode parasites, we investigated whether tuft cells are required for the expulsion of the cestode, Hymenolepis diminuta, from the non-permissive mouse host, and in concomitant anti-helminthic responses. BALB/c and C57BL/6 mice infected with H. diminuta expelled the worms by 11 days post-infection (dpi) and displayed DCLK1+ (doublecortin-like kinase 1) tuft cell hyperplasia in the small intestine (not the colon) at 11 dpi. This tuft cell hyperplasia was dependent on IL-4Rα signalling and adaptive immunity, but not the microbiota. Expulsion of H. diminuta was slowed until at least 14 dpi, but not negated, in tuft cell-deficient Pou2f3-/- mice and was accompanied by delayed goblet cell hyperplasia and slowed small bowel transit. Worm antigen and mitogen evoked production of IL-4 and IL-10 by splenocytes from wild-type and Pou2f3-/- mice was not appreciably different, suggesting similar systemic immune reactivity to infection with H. diminuta. Wild-type and Pou2f3-/- mice infected with H. diminuta displayed partial protection against subsequent infection with the nematode Heligmosomoides bakeri. We speculate that, with respect to H. diminuta, enteric tuft cells are important for local immune events driving the rapidity of H. diminuta expulsion but are not critical in initiating or sustaining systemic Th2 responses that provide concomitant immunity against secondary infection with H. bakeri. Author summary: The small intestinal tuft cell is emerging as a versatile sentinel cell type in a variety of infections involving protozoans, nematodes, and certain bacteria. Whether the tuft cell responds to enteric cestode infections and the extent of its involvement in mediating the anti-helminth response is not yet characterized. Using mice infected with Hymenolepis diminuta, we show that tuft cells help accelerate expulsion of this lumen-dwelling cestode, by coordinating local events that form an integral part of the classical "weep and sweep" anti-helminthic response. We further show that although infection with H. diminuta induces both tuft cell hyperplasia as well as protection from subsequent infection with the nematode Heligmosmoides bakeri, the tuft cell is not solely responsible for mediating systemic and other local Th2 responses against H. diminuta. Our work reveals subtle roles for the tuft cell in initiating and coordinating host anti-parasitic activity in cestode infections. At the same time, we show that redundancies exist in the host's mucosal arsenal that ultimately mediate worm expulsion in tuft cell deficient mice. [ABSTRACT FROM AUTHOR]