CK2 Secreted by Leishmania braziliensis Mediates Macrophage Association Invasion: A Comparative Study between Virulent and Avirulent Promastigotes.

CK2 is a protein kinase distributed in different compartments of Leishmania braziliensis: an externally oriented ecto-CK2, an intracellular CK2, and a secreted CK2. This latter form is constitutively secreted from the parasite (CsCK2), but such secretion may be highly enhanced by the association of specific molecules, including enzyme substrates, which lead to a higher enzymatic activity, called inductively secreted CK2 (IsCK2). Here, we examined the influence of secreted CK2 (sCK2) activity on the infectivity of a virulent L. braziliensis strain. The virulent strain presented 121-fold higher total CK2 activity than those found in an avirulent strain. The use of specific CK2 inhibitors (TBB, DRB, or heparin) inhibited virulent parasite growth, whereas no effect was observed in the avirulent parasites. When these inhibitors were added to the interaction assays between the virulent L. braziliensis strain and macrophages, association index was drastically inhibited. Polyamines enhanced sCK2 activity and increased the association index between parasites and macrophages. Finally, sCK2 and the supernatant of the virulent strain increased the association index between the avirulent strain and macrophages, which was inhibited by TBB. Thus, the kinase enzyme CK2 seems to be important to invasion mechanisms of L. braziliensis.

Efeito da 1, 10-fenantrolina e seus derivados complexados em metal na atividade proteolítica de Leishmania braziliensis / Effect of 1, 10-phenanthroline and its complexed metal derivatives in proteolytic activity of Leishmania braziliensis

Leishmanioses são um grupo de doenças com um largo espectro de manifestações clínicas, as quais variam desde lesões cutâneas até o envolvimento visceral severo, podendo levar ao ótibo. A leishmaniose é, ainda hoje, uma doença negligenciada, estando entre os agravos prioritários do programa de pesquisa sobre doenças da pobreza da Organização Mundial da Saúde (OMS). Além de não haver vacinas disponíveis, a terapia é baseada em medicamentos injetáveis que causam sérios efeitos colaterais, tornando o tratamento inviável para muitos países endêmicos. Drogas derivadas de metal representam um novo arsenal terapêutico antimicrobiano e anti-câncer. Os inibidores de peptidase/agentes quelantes tais como 1,10-fenantrolina e seus derivados, no estado livre de metal ou como ligantes com metais de transição, interferem com a função de vários sistemas biológicos. Em trabalhos anteriores, nosso grupo descreveu que o parasito L. braziliensis produziu moléculas gp63 sensíveis a 1,10-fenantrolina. No presente trabalho, demonstramos a distribuição celular da molécula gp63 em uma cepa virulenta de L. braziliensis por meio de análises bioquímicas e imuno-histoquímica. Depois disso, relatamos os efeitos inibitórios de três compostos derivados da 1,10-fenantrolina, 1,10-fenantrolina-5,6-dioma (phendio), [Cu(phendio)2] e [Ag(phendio)2], nas atividades metalopeptidases celulares e extracelulares produzidas por promastigotas de L. braziliensis, bem como as suas ações sobre a viabilidade do parasita e na interação com as células de macrófagos murinos. As moléculas gp63 foram detectadas em compartimentos de parasitos, incluindo membrana citoplasmatica e bolsa flagelar. O tratamento de promastigotas de L. braziliensis durante 1 hora com 1,10-fenantrolina e seus derivados resultou numa inibição significativa da viabilidade celular e mostrou um mecanismo de ação irreversível. Estes inibidores de metalopeptidases induziram apoptose em promastigotas de L. braziliensis, demonstrada através ...

Leishmaniasis is a group of diseases with a wide spectrum of clinical manifestations, which range from self-limited skin lesions to severe visceral involvement that can lead to death. Leishmaniasis is still a neglected disease, and it is among the priorities of the research program on diseases of poverty of World Health Organization (TDR/WHO). There is no available vaccine and the treatment is based on drugs that cause serious side effects, and are unaffordable in several endemic countries. Metal-based drugs represent a novel antimicrobial and anti-cancer therapeutics arsenal. Peptidase inhibitors/chelating agents such as 1,10-phenanthroline and its substituted derivatives, either the metal-free state or as ligands coordinated to transition metals, interfere with crucial functions of several biological systems. In previous works, our group described that L. braziliensis produced gp63 molecules sensible to 1,10-phenanthroline. Herein, we initially studied the cellular distribution of gp63 in a virulent strain of L. braziliensis by biochemical and immunocytochemical analyses. After that, we reported the inhibitory effects of three 1,10-phenanthroline derivative compounds, 1,10-phenanthroloine-5,6-dione (phendio), [Cu(phendio)2] and [Ag(phendio)2], on both cellular and extracellular metallopeptidase activities produced by L. braziliensis promastigotes as well as their actions on the parasite viability and on the interaction with murine macrophage cells. The gp63 molecules were detected in several parasite compartments, including cytoplasm, membrane lining the cell body and flagellum, and flagellar pocket. The treatment of L. braziliensis promastigotes for 1 hour with 1,10-phenanthroline and its derivatives resulted in a significant inhibition of cell viability and showed an irreversible mechanism of action. These metallopeptidase inhibitors induced apoptosis in L. braziliensis promastigotes as judged by annexin/propidium iodide staining and TUNEL assays ...