7530 Monoacylglycerol metabolism in adipose tissue macrophages

Abstract Disclosure: A. Mooring: None. M. Park: None. J. Bruno: None. J.O. Aleman Diaz: None. White adipose tissue is a heterogeneous organ that is comprised of multiple cell types including adipocytes, nerve cells, endothelial cells and immune cells, each of which are important contributors to adipose tissue homeostasis. Adipose tissue macrophages (ATMs) are key regulators of local and systemic inflammation, adipocyte differentiation and extracellular lipid accumulation. Recent studies evaluating the lipidomic profile of extracellular vesicles (EV) released from adipocytes indicate an association between specific lipid species in EVs and metabolic dysfunction. Individual lipid species influence the crosstalk that occurs between adipocytes and ATMs indicating them as potential molecular messengers. LC-MS analysis performed in our lab has identified monoacylglycerols (MAGs) as the most abundant lipid species in human primary ATMs. However, the role of MAGs in the communication between adipocytes and ATMs remains unclear. To investigate the impact of MAGs on ATMs, we cultured mouse-derived J774.A1 macrophages and treated them with varying concentrations of MAGs (5µM, 50µM, 500µM, 5mM, or 50mM) for 24 hours. We observed significant intracellular lipid accumulation via a targeted LC-MS approach.When MAGs were added to the J774.A1 cell line at a concentration of at least 5mM compared to untreated cells. To further explore this, we employed confocal microscopy to qualitatively assess differences in lipid localization in these cells. We treated an additional cell culture with 50mM of triacylglycerol (TAG) as a control. As anticipated, the cells stored the TAG as lipid droplets. In contrast, cells treated with MAG displayed a dispersed cytosolic storage pattern for the lipid. These findings indicate that the J774.A1 cell line actively stores MAG differently compared to TG. To correlate our cellular findings in human tissues, MALDI imaging was conducted on sections of human visceral adipose tissue. Our in-situ analyses showed spatial anti-correlation between monoglycerides (MAG 20:2, MAG22:2, MAG20:3, MAG 22:3) and triglycerides (TAG 46:9 and TAG 50:8), indicating a distinct location of MAGs within adipose tissue. Our findings provide insights into the accumulation of this neutral lipid within ATMs, as well as its spatial distribution in human tissues. Leveraging these insights may contribute to the development of targeted therapies to mitigate the metabolic complications associated with excess weight. Presentation: 6/1/2024