Interaction of TgMIC1 with Toll-like receptors in the formation of nets induced by Toxoplasma gondii

• Grant number: 17/16464-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2017
• End date: July 31, 2018
• Field of knowledge: Biological Sciences - Immunology - Immunochemistry
• Principal Investigator: Rafael Ricci de Azevedo
• Grantee: Giulia Ballestero
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis. To infect host cells, T. gondii tachyzoites, besides other events, release proteins contained in organelles called micronemes located in the apical region of the parasite. Concerning the microneme proteins (TgMICs), our group isolated the TgMIC1/TgMIC4 subcomplex, whose constituents are lectins that induce IL-12 production by macrophages and, consequently, trigger a protective response against the parasite. Recently, we have shown that the induced secretion of proinflammatory cytokines depends on the interaction of TgMIC1 and TgMIC4 (recombinant forms) with Toll Like Receptors (TLRs), established through the carbohydrate recognition domain of the TgMICs interaction with N-linked glycoproteins to TLRs exodomain. The innate immune response provides several mechanisms that allow the host to counteract the development of toxoplasmosis, including those related to the formation of Neutrophil Extracellular Traps (NETs). NETs correspond to a type of active cell death that occurs through the extrusion of extracellular fibrillar networks. NETs, until recently, were known to be induced only by bacteria; However, recent studies have shown that protozoa, including T. gondii, are also capable of triggering the formation of NETs. However, the mechanisms involved in NETS formation are little known. Recent results from our group clearly indicate that TgMIC1 induces the formation of NETs. This finding led us to suppose that micronema proteins could be responsible for the formation of NETS induced by T. gondii. We further assumed that the known interaction of TgMIC1 with TLRs responded by the formation of NETs by T. gondii. Thus, the aim of the present project is to evaluate if the formation of NETs induced by T. gondii is dependent on the interaction of TgMIC1 with TLRs. To this end, wild T. gondii strains or TgMIC1 knockouts (KO) will be used to infect wild murine neutrophils, TLR2KO or TLR4KO. We will verify the occurrence of NETs in the different combinations of parasite/neutrophil pairs, seeking to identify the possible relevance of the interactions established for triggering protective responses against T. gondii infection. (AU)