A Infecção por Toxoplasma gondii e Neospora caninum é Comprometida pela Ação da Cis-Aconitato Descarboxilase (acod1)

Abstract

Toxoplasma gondii and Neospora caninum are parasites of the Apicomplexa phylum responsible for causing diseases and economic losses worldwide. T. gondii poses a risk to human health and can cause toxoplasmosis, which is known to cause abortions in cases of congenital toxoplasmosis when it is passed from mother to fetus during pregnancy. N. caninum, in turn, is the parasite that causes neosporosis, a zoonosis that affects canines and mainly cattle, causing losses to the agricultural sector due to the loss of animals due to abortion. Given the severity of both diseases, several studies are being conducted to understand the infection process of the parasites and the host's immune response to infection by the parasites. The aconitate decarboxylase 1 (acod1), an enzyme that converts cis-aconitate into itaconate, a metabolite involved in the tricarboxylic acid cycle, and which has several immunometabolic properties. One of the properties of itaconate is the induction of reactive oxygen species (ROS), which are metabolic products that act in favor of the control of parasitic infection. Therefore, the objective of this project was to evaluate the role and interference of acod1 in the host's innate immune response to infection by T. gondii and N. caninum. Sequencing and transcriptome analysis of bone marrow-derived macrophages (BMDMs) infected by both protozoa showed that acod1 is considerably expressed during the parasite infection processes. Thus, to validate the transcriptome data, the gene expression of acod1 was evaluated in vitro (BMDMs) and in vivo, where we confirmed that during acute infection T. gondii and N. caninum increase the expression of acod1 in response to infection, while we observed a decrease in expression in myd88-/- cells, suggesting a role of this adapter protein in the acod1 pathway. To better understand the mechanism of the acod1 pathway, L929 cells genetically depleted for acod1 (acod1-/-) were generated through the CRISPR/Cas9 gene editing technique. Cell morphology was not affected by the absence of the gene, but acod1-/- cells were more susceptible to infection by both parasites when compared to wild-type cells (L929). To understand the mechanism, ROS production was evaluated, and low levels of ROS production were observed in knockout cells due to the absence of the gene and lack of itaconate conversion. Therefore, it is noted that itaconate plays an important role in infection by T. gondii and N. caninum, fostering the need to further understand the activation pathways and immunometabolic properties of acod1.