title: Activation of adipose tissue macrophages in obese mice does not require lymphocytes.
abstract: OBJECTIVE
  Macrophages which infiltrate adipose tissue and secrete proinflammatory cytokines may be responsible for obesity-induced insulin resistance. However, the reason why macrophages migrate into adipose tissue and become activated remains unknown though some studies suggest that this may be regulated by T and B lymphocytes. In this study, it has been tested whether T and B lymphocytes and natural killer (NK) cells were necessary for the obesity-induced activation of macrophages in adipose tissue.
  
  
  METHODS
  NOD/SCID/IL2-receptor gamma-chain knockout (NSG) mice, which lack mature T and B lymphocytes and NK cells, were made obese by selectively reducing litters and weaning onto a high-fat diet. Mice were then maintained on the diet for 10-11 weeks.
  
  
  RESULTS
  Adipose tissue from obese NSG mice had more activated macrophages than nonobese mice. These macrophages were found in "crown-like structures" surrounding adipocytes, and expressed higher levels of the inflammatory cytokine TNF-α. However, obesity did not impair glucose tolerance in the NSG mice.
  
  
  CONCLUSIONS
  These studies demonstrated that T and B lymphocytes and NK cells are not necessary for adipose tissue macrophage activation in obese mice. T and B lymphocytes and/or NK cells may be necessary for the development of obesity-induced impaired glucose tolerance.
authors.affiliation: Division of Endocrinology, Diabetes & Metabolism, Children's Hospital Los Angeles, California, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Behan
authors.forename: Ehsan A
authors.initials: EA
authors.lastname: Ehsanipour
authors.forename: Xia
authors.initials: X
authors.lastname: Sheng
authors.forename: Rocky
authors.initials: R
authors.lastname: Pramanik
authors.forename: Xingchao
authors.initials: X
authors.lastname: Wang
authors.forename: Yao-Te
authors.initials: YT
authors.lastname: Hsieh
authors.forename: Yong-Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Steven D
authors.initials: SD
authors.lastname: Mittelman
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D001823:Body Composition; D059305:Diet, High-Fat; D005260:Female; D018149:Glucose Intolerance; D006728:Hormones / Q000097:blood; D007694:Killer Cells, Natural / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016688:Mice, Inbred NOD; D018345:Mice, Knockout; D016513:Mice, SCID; D009765:Obesity / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D006728:Hormones; D014409:Tumor Necrosis Factor-alpha