MicroRNAs and immunometabolism of macrophages and dendritic cells during the response against Leishmania spp. genus parasites.

Author(s)

Stephanie Maia Acuna

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2023-08-01

Examining board members

Sandra Marcia Muxel; Fernando Ribeiro Gomes; Valeria Marçal Felix de Lima

• Advisor: Sandra Marcia Muxel

Abstract

Leishmaniases are a group of diseases that still today claim fatal victims or leave severe sequelae throughout Brazil and the world. They are caused by protozoan parasites of the genus Leishmania spp., which infect phagocytic cells of the vertebrate immune system, such as macrophages and dendritic cells. These cells can have responses that promote inflammation and eliminate the parasite or responses that allow the survival of the protozoan. The main objective of this thesis is to understand how infection with Leishmania affects the immune responses of murine phagocytes through the modulation of the miRNA profile of macrophages or the metabolic profile of macrophages and dendritic cells. Murine macrophages infected with L. amazonensis show modulation in the expression of non-coding small RNAs, called microRNAs, among which miR-294 stands out. It has inherent expression in L. amazonensis infection and is independent of factors such as the host mouse strain, hormonal modulation with melatonin, or the Toll-like receptor signaling pathway. MiR-294 plays an important role in regulating L-arginine metabolism by modulating the production of nitric oxide by Nitric Oxide Synthase 2 (NOS2) and the arginine transporter CAT2B (cationic amino acid transporter), as well as regulating the expression of the pro-inflammatory cytokine TNFa (tumor necrosis factor). Similarly, the expression of miR-410, which regulates the CAT1B isoform of the L-arginine transporter, is observed. The metabolism of this amino acid has emerged as one of the most modulated during macrophage infection with L. amazonensis in the metabolomic profile. From it, the production of antioxidant molecules such as glutathione and trypanothione is carried out, which showed changes in their concentrations and in the ratio between oxidized and reduced forms, indicating changes in the redox state. This is influenced by the mitochondrial state, such as the presence of a spontaneous mutation in the Nicotinamide Nucleotide Transhydrogenase (NNT) gene, responsible for the greater production of the mitochondrial NADPH pool, an important co-factor in glutathione recycling. Without functional NNT, macrophages from a resistant lineage become as susceptible as NOS2 knockouts. Regarding dendritic cells, it was observed that infection with L. infantum leads to an increase in ATP production dependent on the oxidation of glucose to lactate, indicating inhibited mitochondrial respiration. Together, the data suggest a strong relationship between the immune function of host cells, the metabolic state, and the regulation of gene expression mediated by miRNAs. (AU)

• FAPESP's process: 17/23519-2 - Analysis of role of miRNAs and transcription factors on the regulation of gene expression of Leishmania amazonensis infected murine macrophages
• Grantee: Stephanie Maia Acuna
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)