Papel de vesículas extracelulares de adipócitos na ativação de macrófagos durante a infecção in vitro por Mycobacterium bovis BCG: Análise do metabolismo lipídico e resposta inflamatória

Abstract

Obesity is characterized by a chronic low-grade inflammatory state, known as metainflammation. Factors secreted by adipocytes, including extracellular vesicles (EVs), have been proposed as modulators of macrophage function and profile, enhancing metabolic inflammation processes. In addition, transcription factors such as PPARγ play a significant role in regulating macrophage function and are involved in the biogenesis of lipid droplets (LDs) during BCG infection. LDs are dynamic organelles involved in lipid storage, synthesis of inflammatory mediators, cellular signaling, and act as a survival niche for intracellular pathogens. However, little is known about the role of adipocyte-derived EVs in regulating lipid metabolism signaling pathways and the progression of infections by intracellular pathogens. Objectives: To analyze the interactions between adipocyte-derived EVs and macrophage activation during Mycobacterium bovis BCG infection, in vitro. Methods: LDs were quantified using fluorescence microscopy, and cytokine levels were measured by ELISA. EVs were isolated using a series of centrifugation steps, characterized, and quantified by flow cytometry, Zeta Size analysis, and Micro BCA. Results: Specific subpopulations of EVs, namely microvesicles and exosomes, positively influenced LD formation and macrophage activation during BCG infection. They induced TNF-α synthesis, and specifically, microvesicles were able to induce KC synthesis, which was negatively modulated in the infected groups. However, this effect was not observed in macrophages stimulated with exosomes. Conclusion: Our findings suggest that adipocyte-derived EVs play a crucial role in macrophages infected with BCG, promoting LD formation and cytokine synthesis. However, further studies are needed to fully understand the complex interactions between adipocytes and macrophages during infections caused by intracellular pathogens such as BCG.