title: Adipose tissue macrophages: phenotypic plasticity and diversity in lean and obese states.
abstract: OBJECTIVE
  Proinflammatory adipose tissue macrophages (ATMs) contribute to obesity-associated disease morbidity. We will provide an update of the current state of knowledge regarding the phenotypic and functional diversity of ATMs in lean and obese mice and humans.
  
  
  RESULTS
  The phenotypic diversity of ATMs is now known to include more than two types requiring an expansion of the simple concept of an M2 to M1 shift with obesity. Potential functions for ATMs now include the regulation of fibrosis and response to acute lipolysis in states of caloric restriction. Novel pathways that can potentiate ATM action have been identified, which include inflammasome activation and the response to lipodystrophic adipose tissue. Studies provide a new appreciation for the ability of ATMs to respond dynamically to the adipose tissue microenvironment.
  
  
  CONCLUSIONS
  ATMs play a key role in shaping the inflammatory milieu within adipose tissue, and it is now apparent that ATM heterogeneity is acutely shaped by the adipose tissue environment. To account for the new findings, we propose a new nomenclature for ATM subtypes that takes into account their diversity.
authors.affiliation: Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, University of Michigan, Ann Arbor, Michigan 48109-5652, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Morris
authors.forename: Kanakadurga
authors.initials: K
authors.lastname: Singer
authors.forename: Carey N
authors.initials: CN
authors.lastname: Lumeng
mesh_terms: D000273:Adipose Tissue / Q000166:cytology* / Q000503:physiopathology*; D000818:Animals; D039521:CD11c Antigen / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism; D005355:Fibrosis; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D037181:Lectins, C-Type / Q000378:metabolism; D008060:Lipodystrophy / Q000503:physiopathology; D008066:Lipolysis; D008264:Macrophages / Q000378:metabolism*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D051379:Mice; D008820:Mice, Obese; D009765:Obesity / Q000503:physiopathology; D010641:Phenotype; D011956:Receptors, Cell Surface / Q000378:metabolism; D013851:Thinness / Q000503:physiopathology; D014280:Triglycerides / Q000378:metabolism
chemical_list: D039521:CD11c Antigen; D002518:Ceramides; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D014280:Triglycerides