Estudo do perfil de ativação da via MAPK em células Hela induzido por formas Amastigotas Extracelulares (AEs) das cepas G e CL de Trypanosoma cruzi

Abstract

Trypanosoma cruzi, the etiologic agent of Chagas Disease, which affects about 7 millions people induces MAPK pathway activation during cell invasion, favoring its entry and survival. Mitogen-activated protein kinases (MAPKs) phosphorylate their substrates at serine and threonine residues sites to activate or de-activate their target. There are three well-known MAPK pathways in mammalian cells: ERK1/2 – activated by growth factor, hormones and proinflammatory stimuli -, c-JUN N-terminal kinase (JNK1/2/3), and p38 MAPK (α, β, δ, and γ) - activated by cellular and environmental stresses, in addition to proinflammatory stimuli. These pathways mediate the immune response formation through activation of different proteins and consequent synthesis of inflammatory and anti-inflammatory cytokines/interleukins. Extracellular Amastigotes (EAs), an infectious alternative form of T. cruzi, are prematurely released from infected cells or generated by extracellular differentiation of trypomastigote forms. EAs of G strain are more infective than EAs of CL strain. The present study aimed to elucidate the activation profile of MAPK pathway in HeLa cells mediated by the invasion of T. cruzi EAs of G and CL strains and the possible effects on host immune response modulation in vitro. In experiments using MAPK inhibitors, ERK1/2, EGFR and p38 inhibitors seemed to reduce the invasion rate of EAs of G strain. EAs of G strain induced a biphasic phosphorylation of MEK-ERK pathway, possibly due to its higher infectivity. Furthermore, it is possible that EGF receptor (EGFR) is activated in early phases of cell invasion, at adhesion time, and deactivated soon after adhesion, possibly explained by parasite EGF sequestration. CL EAs induced expression of IL-8, IL-6 and TNF-α. EAs of G strain activated the production of interleukins/cytokines IL-6, TNF-α, TGF-β and cFOS transcription factor. To understand how this pathway is activated by pathogens is crucial to broaden possibilities for future studies, mainly relating this pathway to Trypanosoma cruzi evolutive forms of different strains with greater clinical importance in humans.