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

MILTEFOSINE EXERTS ITS LEISHMANICIDAL ACTION VIA PAF
RECEPTOR
ANA CLARA M. MONTUORI 2 ; WALDIONÊ DE CASTRO 1,2 ; YURI C. KARLIN 2 ;
MATHEUS B. H. CARNEIRO 2 ; DANIEL M. ALMEIDA 1 ; PAULA S.MELLO 2 ;
BHASKAR SAHA 3 ; LEDA QUERCIA VIEIRA 1,2 .
1 Núcleo de Pesquisa em Ciências Biológicas (NUPEB), Universidade Federal
de Ouro Preto,Minas Gerais, Brasil
2 Departamento de Bioquímica e Imunologia, ICB, Universidade Federal de
Minas Gerais, Minas Gerais, Brasil.
3 National Centre for Cell Science , Ganeshkhind, Pune, India.
Miltefosine (hexadecylphosphocolina - HPC), which was first used as
treatment in patients with cancer, has been used as an effective oral drug in
visceral leishmaniasis. There is a structural similarity between miltefosine and
platelet activating factor (PAF). PAF acts by binding to the PAF receptor (PAFR)
present in target cells. The mechanism by which the drug works is not well
established.
Objective: The objective of this study is to verify if the mechanism of action of
miltefosine is mediated by the PAF receptor (PAFR). Methodology:To test this
hypothesis, BALB/c and PAFR -/- mice were orally treated from the 14th day after
infection (2x10 7 promastigotes inoculated intra-venously into the tail vein) for 7
consecutive days at dose 20mg/kg/day and killed on day 28. Parasites
quantification was made by serial dilution, measurement of serum cytokine
analysis by ELISA and the activity of Arginase I and NO production from
peritoneal macrophages.Results: Here, we report that both miltefosine and
PAF bind to PAF receptor (PAFR), as suggested by the modeling data and
similarities in activating the p38MAPK and ERK-1/2- and Leishmania killing in
macrophages. Miltefosine-induced p38MAPK activation was inhibited by PAF
antagonist and anti-PAFR antibodies. The PAF antagonist reduced the
miltefosine-induced TNF-α production and Leishmania killing. Initially we found
that macrophages from wild type mice and PAFR-KO showed a similar profile of
infection when infected with L. donovani. The in vitro infection experiments
revealed that macrophages from wild type mice treated with miltefosine were
more effective in controlling the growth of the parasites than macrophages from
PAFR-KO mice. We found that in vivo infection with L. donovani showed no
differences in susceptibility between wild-type mice and PAFR-KO. We treated
wild type mice and PAFR-KO orally from day 14 after infection with L. donovani
for seven consecutive days with 20mg/kg/day of miltefosine. Our data revealed
that treatment of wild type mice led to a reduction in parasite load in the liver
and spleen of these animals. Interestingly, PAFR-KO mice showed a higher
parasite load in these organs. Conclusions: These data define for the first time
the mechanistic basis of host cell-dependent anti-leishmanial function of