INVESTIGADORES
CARGNELUTTI Diego Esteban
congresos y reuniones científicas
Título:
Immune and pathological parameters in BALB/c mice infected with low and high-dose of Leishmania amazonensis.
Autor/es:
CARGNELUTTI D.E.; SANCHEZ M.V.; MOREA G.; GARCÍA BUSTOS M.F.; SALOMÓN M.C.; SCODELLER E.A.; GEA S.
Lugar:
Recife
Reunión:
Congreso; V World Leishmania Congress; 2013
Institución organizadora:
Oswaldo Cruz Foundation
Resumen:
Human leishmaniasis is a neglected endemic disease
caused by more than 20 Leishmania
species and with a broad spectrum of clinical manifestations. Leishmania amazonensis, an etiological agent of localized and diffuse
cutaneous leishmaniasis in South America also cause severe pathology in BALB/c
mice displaying persistent lesions. In this study, we comparatively investigated the
impact of infection in immune
response and tissue damage using BALB/c mice infected with low (103)
and high (106) number of L.
amazonensis metacyclic promastigotes (MHOM/VE/84/MEL). BALB/c mice (eight to nine week old; n: 5 per group) were infected with 103or 106parasites into the dermis of
the footpad and the evolution of infection was assessed until day 70
post-infection. Uninfected mice were used as controls. The appearance of
lesions in mice infected with 103 parasites was delayed compared to mice
infected with 106 parasites. The study of the humoral immune response
revealed the induction of specific IgG antibodies, IgG1 and IgG2a
isotypes. Mice infected with 103
parasites presented lower levels of reactivity of IgG, IgG1 and IgG2a
antibodies than mice infected with 106 promastigotes at 70 days post
infection. However, the relation between the two antibody isotypes was similar
in the two experimental conditions. These results indirectly suggest a
simultaneous activation of Th1 and Th2 T lymphocytes. In addition, the low
production of nitric oxide in splenocyte culture supernatants (about 3.5 mM)
suggests a reduction in inducible nitric oxide synthase (iNOS) activation.
These results were associated with high splenic index and lesion histological
score (more than 20) with inflammatory infiltrate at the site of infection.
Thus, these latter findings did not reveal significant differences between the
experimental groups. In summary, our data show that the appearance of lesions
in mice infected with low dose of parasites was delayed compared to mice
infected with high dose of Leishmania. However, low-dose infection did
not result in changes neither the lesion susceptibility nor histological
parameters described for subcutaneous infection with high
numbers of parasites. We postulated that L.
amazonensis has developed strategies
to escape from host defense favoring the establishment and success of the
infection.