Platelet-Activating Factor Receptor Deficiency Delays Elimination of Adult Worms but Reduces Fecundity in Strongyloides venezuelensis-Infected Mice

AUTOR(ES)

Negrão-Corrêa, Deborah

FONTE

American Society for Microbiology

RESUMO

We describe the parasitological kinetics and histopathological and immunological alterations in platelet-activating factor receptor-deficient (PAFR−/−) and wild-type mice after a single Strongyloides venezuelensis infection (subcutaneous inoculation of 500 L3 larvae). There was no difference in the numbers of worms that reached and became established in the small intestines of PAFR−/− and wild-type mice. However, at 12 days after infection, significantly more worms were recovered from PAFR−/− mice. Although PAFR−/− infected mice showed a delay in elimination of adult worms, worms established in the small intestine of these mice produced a significantly lower number of eggs due to a reduction in worm fecundity. There were also significant reductions in the number of circulating and tissue eosinophils and tumor necrosis factor levels in the small intestines of PAFR−/− mice infected for 7 days compared to the number and level in wild-type mice. Histological analysis confirmed the reduced inflammatory process and revealed that the PAFR−/− mice had a smaller number of goblet cells. The concentrations of the type 2 cytokines interleukin-4 (IL-4), IL-5, and IL-10 were lower in small intestine homogenates and in supernatants of antigen-stimulated lymphocytes from spleens or mesenteric lymph nodes of PAFR−/− mice than in the corresponding preparations from wild-type mice. Thus, in S. venezuelensis-infected PAFR−/− mice, decreased intestinal inflammation is associated with enhanced worm survival but decreased fecundity. We suggest that although a Th2-predominant inflammatory response decreases worm survival, the worm may use factors produced during this response to facilitate egg output and reproduction. PAFR-mediated responses appear to modulate these host-derived signals that are important for worm fecundity.

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