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PAGES: DOI: 10.1590/0074-02760170345 Full paper
In vitro evaluation of the anti-leishmanial activity and toxicity of PK11195

Carlos Eduardo Sampaio Guedes1, Beatriz Rocha Simões Dias1, Antonio Luis de Oliveira Almeida Petersen1, Kercia Pinheiro Cruz1, Niara de Jesus Almeida1, Daniela Rodrigues Andrade2, Juliana Perrone Bezerra de Menezes1, Valéria de Matos Borges2, Patricia Sampaio Tavares Veras1,+

1Fundação Oswaldo Cruz-Fiocruz, Centro de Pesquisas Gonçalo Moniz, Laboratório de Patologia e Biointervenção, Salvador, BA, Brasil
2Fundação Oswaldo Cruz-Fiocruz, Centro de Pesquisas Gonçalo Moniz, Laboratório Integrado de Microbiologia e Imunoregulação, Salvador, BA, Brasil


BACKGROUND Leishmaniasis, one of the most neglected diseases, is a serious public health problem in many countries, including Brazil. Currently available treatments require long-term use and have serious side effects, necessitating the development of new therapeutic interventions. Because translocator protein (TSPO) levels are reduced in Leishmania amazonensis-infected cells and because this protein participates in apoptosis and immunomodulation, TSPO represents a potential target for Leishmania chemotherapy. The present study evaluated PK11195, a ligand of this protein, as an anti-leishmanial agent.

OBJECTIVE To evaluate the leishmanicidal activity of PK11195 against L. amazonensis in infected CBA mouse macrophages in vitro.

METHODS The viability of axenic L. amazonensis, Leishmania major, and Leishmania braziliensis promastigotes was assessed after 48 h treatment with PK11195 (0.2-400 µM). Additionally, intracellular parasite viability was evaluated to determine IC50 values and the number of viable parasites in infected macrophages treated with PK11195 (50-100 µM). Infected macrophages were then treated with PK11195 (25-100 µM) to determine the percentage of L. amazonensis-infected cells and the number of parasites per infected cell. Electron microscopy was used to investigate morphological changes caused by PK11195. The production of free oxygen radicals, nitric oxide, and pro-inflammatory cytokines was also evaluated in infected macrophages treated with PK11195 and primed or not primed with IFN-γ.

FINDINGS Median IC50 values for PK11195 were 14.2 µM for L. amazonensis, 8.2 µM for L. major, and 3.5 µM for L. braziliensis. The selective index value for L. amazonensis was 13.7, indicating the safety of PK11195 for future testing in mammals. Time- and dose-dependent reductions in the percentage of infected macrophages, the number of parasites per infected macrophage, and the number of viable intracellular parasites were observed. Electron microscopy revealed some morphological alterations suggestive of autophagy. Interestingly, MCP-1 and superoxide levels were reduced in L. amazonensis-infected macrophages treated with PK11195.

MAIN CONCLUSIONS PK11195 causes the killing of amastigotes in vitro by mechanisms independent of inflammatory mediators and causes morphological alterations within Leishmania parasites, suggestive of autophagy, at doses that are non-toxic to macrophages. Thus, this molecule has demonstrated potential as an anti-leishmanial agent.

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Financial support: FAPESB, CNPq.
PSTV holds a grant from CNPq for productivity in research (307832/2015-5).
CESG and BRSD contributed equally to this work.
+ Corresponding author: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.
Received 24 August 2017
Accepted 30 November 2017