Differences in Metabolic Activity Between Macrophage Populations in Response to LPS-Stimulation and Glutamine Inhibition
Year: 2021
Type: conference-abstract
Abstract: RATIONALE: Metabolic programming is a critical regulator of inflammatory responses. Our prior work has shown that inhibition of glutamine metabolism accelerates resolution of LPS-induced acute lung injury (ALI) in vivo. We found that inhibition of glutamine metabolism reduced the number of neutrophils, inflammatory macrophages, and interstitial macrophages within the lungs, but did not affect the number of alveolar macrophages (AM). This study evaluated the effect of inhibiting glutamine uptake and metabolism on the metabolic activity of two populations of macrophages: AM and bone marrow-derived macrophages (BMDM). BMDM were used to represent inflammatory macrophages in the lungs. METHODS: Murine BMDM and AM were stimulated with LPS (100 ng/ml) or media for 4 hours with or without the glutamine inhibitor, 6-diazo-5-oxo-L-noreleucine (DON, 5 M), which was added at the start of the third hour and was present for the last 2 hours. Macrophages were then collected, and metabolites were analyzed by ultrahigh performance liquid chromatography-tandem mass spectroscopy by Metabolon (Research Triangle Park, NC). RESULTS: Unstimulated AM and BMDM exposed to only media without DON demonstrated significant differences in their metabolome. AM had more carbohydrate metabolites and less amino acid metabolites and nucleotide metabolites. Stimulation with LPS did not alter the metabolome of AM and increased only the concentration of methylmalonate in BMDM. Interestingly, DON exposure led to changes in multiple metabolic pathways in AM; however, there were no changes in the metabolome of BMDM. The effects of DON exposure were similar with and without LPS stimulation. Within AM, DON exposure led to an increase in carbohydrate metabolites and nucleotide metabolites, and it altered amino acid and lipid metabolites. CONCLUSIONS: Our findings indicate that unstimulated AM and BMDM are strikingly different in the metabolic pathways that they utilize. They also respond differently to inhibition of glutamine metabolism; the AMs alter numerous pathways, whereas the BMDM metabolism either is not dependent on glutamine or can compensate for the loss of glutamine utilization. Curiously, DON caused similar changes in each population with and without LPS stimulation. This suggests that the ability of DON to enhance resolution of ALI is through effects on AM, rather than BMDM. These data suggest that targeting metabolism can selectively affect the activity of different populations of macrophages. Funding source: 1K08HL148529 (to C.L.V.
Authors: C.L. Vigeland, H.S. Beggs, H. Dang, C.M. Doerschuk
Institution: University of North Carolina at Chapel Hill
Language: English
Topic: Immune cells in cancer
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: gold
OpenAlex ID: W4248082116