Abstract
We apply stable isotope tracing, mass-spectrometry-based untargeted metabolomics, to reveal the biochemical space labeled by 13C-substrates in bone-marrow-derived macrophages. At the pathway level, classically (lipopolysaccharide [LPS]-polarized, M1)and alternatively (interleukin [IL]-4-polarized, M2)polarized macrophages were 13C-labeled with surprising concordance. Total pools of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), an intermediate in the hexosamine biosynthetic pathway, were equally abundant in LPS- and IL-4-polarized macrophages. Informatic scrutiny of 13C-isotopologues revealed that LPS-polarized macrophages leverage the pentose phosphate pathway to generate UDP-GlcNAc, whereas IL-4-polarized macrophages rely on intact glucose and mitochondrial metabolism of glucose carbon. Labeling from [13C]glucose is competed by unlabeled fatty acids and acetoacetate, underscoring the broad roles for substrate metabolism beyond energy conversion. Finally, the LPS-polarized macrophage metabolite itaconate is imported into IL-4-polarized macrophages, in which it reprograms [13C]glucose metabolism. Thus, use of fully unsupervised isotope tracing metabolomics in macrophages reveals polarization-state-specific metabolic pathway connectivity, substrate competition, and metabolite allocation among cellular compartments.
Original language | English (US) |
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Pages (from-to) | 298-313 |
Number of pages | 16 |
Journal | iScience |
Volume | 9 |
DOIs | |
State | Published - Nov 30 2018 |
Bibliographical note
Funding Information:The authors thank Alisa Nelson for helpful discussions, J. Matthew Gandy and Matthew Longo for assistance with mouse husbandry, Laura Kyro for graphics expertise, and Peter Phelan for guidance on primary macrophage isolation and culture. This work was supported in part by grants from the NIH (DK091538, CA235482, ES028365, and OD024624). Conceptualization, P.P. X. Huang, and P.A.C.; Methodology, P.P. X. Huang, S.M. G.J.P. and P.A.C.; Investigation, P.P. X. Huang, S.M.; Resources, P.A.C.; Writing – Original Draft, P.P. and P.A.C.; Writing – Review & Editing, all authors; Visualization, P.P. X. Huang, and P.A.C.; Supervision, X. Han, G.J.P. and P.A.C.; Funding Acquisition, P.A.C. The authors declare no conflict of interest.
Funding Information:
The authors thank Alisa Nelson for helpful discussions, J. Matthew Gandy and Matthew Longo for assistance with mouse husbandry, Laura Kyro for graphics expertise, and Peter Phelan for guidance on primary macrophage isolation and culture. This work was supported in part by grants from the NIH ( DK091538 , CA235482 , ES028365 , and OD024624 ).
Publisher Copyright:
© 2018 The Authors
Keywords
- Components of the Immune System
- Immunology
- Metabolomics