immunology of infectious and parasitic diseases - XXXVII Congress ...

ROLE OF STRONGYLOIDES VENEZUELENSIS INFECTION IN THE
EVOLUTION OF EXPERIMENTALLY INDUCED COLITIS IN MICE
Rodrigues, VF1; Bahia, MPS1; Cândido, NR1; Pereira, CAJ1; Araújo, ES1;
Rodrigues, JL1; Corrêa, O1; Negrão-Corrêa, D1. 1 – Universidade Federal de
Minas Gerais
Introduction:The infection with intestinal nematode, such as Strongyloides,
induces a modified type-2 immune response, in which cytokines of type 2 and
regulatory are produced. Epidemiologic studies suggested that nematodeinduced
immune response also has the ability to modulate unrelated
inflammation such as inflammatory bowel disease (IBD), a chronic inflammatory
disorder that manifests in a dysregulated mucosal immune response against
intestinal bacteria. However, the mechanisms involved in this modulation
process are not well established and is probably dependent on the nematode
life cycle. In this experimental work, we intent to verify the effect of
Strongyloides venezuelensis infection, a nematode that establishes into the
small intestine mucosa and it is spontaneously eliminated after 2 weeks,
infection on the evolution of Dextran sodium sulfate (DSS)-induced colitis in
mice. Methods and Results:For this proposal, Balb/c female mice were
subcutaneously infected with 700 L3 of S. venezuelensis and after 5 days they
received drinking water containing 4 % of DSS for 7 days. Groups of Balb/c only
infected or only treated with DSS were kept as control. Colitis score was
determined based on weight loss, fecal blood and diarrhea, and clinical
appearance. Upon autopsy, at 12 days of infection, parasite burden and the
length of the colon were determined. Samples of small and large intestine were
recovered for cytokine quantification and histopatologic analysis. The data
showed that DSS-induced colitis did not interfere with the parasite burden, but
S. venezuelensis infection significantly reduced the colitis score. Compare to
DSS-treated mice, the infected and treated animals also showed lower cellular
infiltration and mieloperoxidase activity, but higher eosinophil peroxidase in
colon. At the time of autopsy, the colon of mice infected and DSS-treated mice
had higher levels of type-2 cytokines (IL-4 and IL-13) but similar levels of IL-10
and type-1 cytokine compare to DSS-treated mice. Conclusion:Our data
indicates that S. venezuelensis infection is able to modulate DSS-induced colitis
in mice. The results also suggested that the modulation was due to the increase
of type-2 response in colon.
Financial support: Fapemig e CNPq