Alterations in phenotypic profiles of peripheral blood cells from patients with human American cutaneous leishmaniasis following treatment with an antimonial drug and a vaccine.

The susceptibility or resistance of a vertebrate host to leishmaniasis is related to the species of Leishmania and to the host immune response of the host. In the present study, the phenotypic profiles of the peripheral blood cells of patients with American cutaneous leishmaniasis (ACL) were evaluated before and after receiving three different therapeutic regimens. The study population comprised 24 patients, living in an ACL-endemic area of Caratinga (MG, Brazil), who had been diagnosed as ACL-positive on the basis of characteristic lesions, the Montenegro skin reactivity test, and/or positive parasitology. Subjects were divided into three groups and received treatment regimens based on (i) the pentavalent antimonial (SbV) N-methyl meglumine antimoniate (Glucantime), (ii) the vaccine Leishvacin, or (iii) SbV in association with the vaccine. Comparative analyses of peripheral mononuclear cells prior to and after treatment revealed that the therapeutic regimens induced no significant differences in the percentages of CD3+ and CD4+ T lymphocytes, CD19+ B lymphocytes, or CD16+ and CD56+ natural killer cells. Additionally, the CD4/CD8 and CD3/CD19 ratios remained unaltered by any of the treatments applied. Most previous studies in the field have focused on the analysis of peripheral blood from ACL patients following in vitro stimulation with either Leishmania antigens or mitogens. The ex vivo cellular immune phenotypic profiles determined in the present study, however, revealed that different ACL treatments did not significantly alter either the immune response exhibited by a patient prior to therapy or the expected cure rate.

Synthesis, antimalarial activity, and intracellular targets of MEFAS, a new hybrid compound derived from mefloquine and artesunate.

A new synthetic antimalarial drug, a salt derived from two antimalarial molecules, mefloquine (MQ) and artesunate (AS), here named MEFAS, has been tested for its pharmacological activity. Combinations of AS plus MQ hydrochloride are currently being used in areas with drug-resistant Plasmodium falciparum parasites; although AS clears parasitemia in shorter time periods than any other antimalarial drug, it does not cure infected patients; in addition, MQ causes side effects and is rather expensive, important problems considering that malaria affects mostly populations in poor countries. Here, we show that MEFAS is more effective than the combination of AS and MQ, tested in parallel at different mass proportions, against P. falciparum (chloroquine-resistant clone W2 and chloroquine-sensitive clone 3D7) in vitro and in mice infected with Plasmodium berghei, promoting cure of this infection. MEFAS tested against HepG2 hepatoma cells exhibited lower toxicity than the antimalarials AS and MQ alone or combined. Possible targets of MEFAS have been studied by confocal microscopy using fluorescent probes (Fluo-4 AM and BCECF-AM) in P. falciparum synchronous culture of W2-infected red blood cells. Dynamic images show that MEFAS exhibited intracellular action increasing cytoplasmic Ca(2+) at 1.0 ng/ml. This effect was also observed in the presence of tapsigargin, an inhibitor of SERCA, suggesting an intracellular target distinct from the endoplasmic reticulum. Trophozoites loaded with BCECF-AM, when treated with MEFAS, were still able to mobilize protons from the digestive vacuole (DV), altering the pH gradient. However, in the presence of bafilomycin A1, an inhibitor of the H(+) pump from acidic compartments of eukaryotic cells, MEFAS had no action on the DV. In conclusion, the endoplasmic reticulum and DV are intracellular targets for MEFAS in Plasmodium sp., suggesting two modes of action of this new salt. Our data support MEFAS as a candidate for treating human malaria.