Integrated Analysis of Sphingolipid Metabolism and Extracellular Particle Composition in the Context of a Hight-Fat-Diet: Implications for Lipoproteins, Vesicle Biogenesis, and the Role in Macrophage Response to COVID-19

Abstract

Sphingolipids (SL) are structurally and functionally diverse molecules with important physiological functions, found associated with cell membranes, plasma lipoproteins, or extracellular vesicles (EV). Concentrations of SL are altered in various metabolic disorders such as obesity, implicating the regulation of inflammation, apoptosis, cell proliferation, autophagy, and insulin resistance. Obesity has been considered a comorbidity factor for severe COVID-19 caused by the SARS-CoV-2 virus, although the mechanisms related to this condition are still poorly understood. In this context, SL, which is modified in high-fat diets (HFD), has been described as critical factors in the regulation of viral replication and innate immune response. Indeed, our research group, using quantitative sphingolipidomic technology, has demonstrated SL species as clinical and inflammatory markers associated with COVID-19 in patients. Therefore, understanding the metabolic variations of SL and their influence on the response to SARS-CoV-2 infection will be crucial for the development of effective therapies and preventing "long COVID." In this project, we propose an integrated approach to evaluating SL metabolism and its transport/composition in lipoproteins and EV, using an experimental metabolic condition of HFD. Additionally, we will explore the influence of SL-carrying extracellular particles on macrophage response to COVID-19. Our strategies include: i) murine experimental model - purification and characterization of lipoproteins (HDL, LDL, VLDL), EV, and plasma exosomes from animals on HFD and/or treated with inhibitors of SL and cholesterol metabolism enzymes; ii) in vitro cell culture model - inflammatory and antiviral response of macrophages to SARS-CoV-2 infection, and/or incubation with extracellular lipid particles; iii) bioanalytics - determining SL content in various lipid particles through quantitative mass spectrometry (LC-MS/MS); iv) translational human model - reanalyzing lipidomic and lipid profile data from COVID-19 patients' plasma, stratifying by body mass index (BMI) and gender. Thus, this study will advance understanding of SL metabolism modulation in comorbidity conditions and pathophysiology, as well as potential therapeutic intervention strategies and the use of biomarkers in COVID-19. (AU)