ROLE OF GASDERMIN-D IN THE CONTROL OF TOXOPLASMA GONDII INFECTION IN MACROPHAGES

Author(s)

Luiza Zainotti Miguel Fahur Bottino

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2022-02-02

Examining board members

Karina Ramalho Bortoluci; Cristina Ribeiro de Barros Cardoso; Alexandra Ivo de Medeiros; Pedro Manoel Mendes de Moraes Vieira

• Advisor: Karina Ramalho Bortoluci

Abstract

Canonical inflammasomes are multiprotein platforms that activate caspase-1, which is responsible for processing IL-1 &#946 and IL-18 cytokines and pyroptosis induction. Pyroptosis is an extremely inflammatory cell death process that can be involved in the control of infections caused by intracellular pathogens. The molecular regulation of this process has been recently described and involves the cleavage of Gasdermin D (GSDMD) by caspases-1 and -11, raising this molecule as a key mediator of pyroptosis induced by canonical and non-canonical inflammasomes. Since the role of GSDMD in controlling protozoa infections has not been not fully elucidated, the aim of this project is to evaluate the ability of Toxoplasma gondii to induce GSDMD cleavage and to verify the influence of this process in the control of infection by macrophages. As expected, GSDMD-deficient macrophages were more resistant to cell death in response to a well-documented inflammasome agonist. Our data demonstrates that T. gondii was able to induce GSDMD cleavage and IL-1 secretion in wild-type macrophages. Surprisingly, the GSDMD-/- macrophages presented higher efficiency in controlling T. gondii replication, which was not correlated with inflammatory cytokines secretion. On the other hand, a higher production of nitric oxide (NO) induced at transcritptional level was pointed as a key infection-limiting mechanism in GSDMD-/- macrophages in response to T. gondii . Taken together, our data suggests a non-convetional role for GSDMD in limiting NO production, with significant consequences on the outcome of T. gondii infection. Of importance, GSDMD appears to act in a context-dependent fashion since preliminary data showed that GSDMD-/- macrophages show attenuated levels of NO in response to Trypanosoma cruzi and are more susceptible to parasite replication. Our data demonstrates the participation of GSDMD in the control of protozoa infections by a mechanism that involves the regulation of microbicidal enzymes and highlight the complex connectivity between the molecular signaling pathways triggered by the inflammasomes in the pathogen-host interactions. (AU)

• FAPESP's process: 19/13631-5 - Role of pyroptosis in the control of Toxoplasma gondii infection in different cell types
• Grantee: Luiza Zainotti Miguel Fahur Bottino
• Support Opportunities: Scholarships in Brazil - Master