Figure 1.

Adipose tissue macrophage-mediated adaptive thermogenesis in brown and beige adipocytes. Distinct macrophage subpopulations within thermogenic adipose tissues, including brown and subcutaneous white fat, support functions of brown or beige adipocytes to dissipate energy and regulate systemic energy homeostasis. Alternatively activated M2 and cholinergic adipose macrophages activate thermogenic responses in brown or beige adipocytes through paracrine mechanisms in a cold environment (red arrows). On the other hand, thermogenic inhibitory ATM subsets that block sympathetic innervation or import/degrade catecholamine have been identified in thermogenic adipose niches (red blunt-ended lines). AR, adrenergic receptor; ChAT, choline acetyltransferase; CHRNA2, neuronal acetylcholine receptor subunit alpha 2; CXCL14, C-X-C motif chemokine ligand 14; MAOA, monoamine oxidase A; MECP2, methyl-CpG binding protein 2; NE, norepinephrine; PLEXA4, plexin A4; ROBO1, roundabout guidance receptor 1; SEMA6a, semaphoring 6a; SLC6a2, solute carrier family 6 member 2; SLIT3, slit guidance ligand 3; TH, tyrosine hydroxylase.