Targeting glutaminolysis pathway in trained immunity induced by oxidized low-density lipoprotein

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft DFG Atherosclerosis is a chronic inflammatory disease of the arterial wall that causes cardiovascular disease. Monocyte-derived macrophages importantly contribute to atherogenesis. Monocytes can be primed to exhibit increased responsiveness upon a secondary non-related stimulus, a phenomenon called trained immunity. Intracellular metabolic and epigenetic reprogramming lays the basis of trained immunity. One of the stimuli that can induce trained immunity is oxidized low-density lipoprotein (oxLDL). oxLDL-trained monocytes exhibit an increase in metabolic pathways such as glycolysis, OXPHOS, and cholesterol biosynthesis. The glutaminolysis pathway that fuels the tricarboxylic acid (TCA) cycle is essential for trained immunity induction by b-glucan, the cell wall component of Candida albicans. The goal of this project is to investigate the involvement of the glutaminolysis pathway in oxLDL-induced trained immunity in isolated human primary monocytes. We exposed monocytes for 24 hours to oxLDL, allowed subsequent differentiation into macrophages for six days in culture medium, and assessed cytokine production capacity upon restimulation. Co-incubation of oxLDL with the inhibitor that blocks glutaminase, the enzyme that generates glutamate from glutamine, significantly reduced cytokine production capacity in oxLDL-trained cells. We further showed that glutaminolysis is necessary for oxLDL-induced increase in oxygen consumption (OCR) and glycolysis rate (ECAR). Single nucleotide polymorphisms in glutaminolysis genes were shown to correlate with ex vivo oxLDL-induced trained immunity in 243 healthy volunteers. These data suggest an important role of glutaminolysis in the establishment of oxLDL-induced trained immunity. To unravel the molecular mechanisms behind this observation we plan to perform epigenetic as well as metabolic analyses of the monocytes trained in the presence of the inhibitor.