Adipose tissue recruitment of leukocytes.
OBJECTIVE
In December of 2003, two seminal articles describing the presence of macrophages in obese adipose tissue were published. These adipose tissue macrophages (ATMs) are inflammatory and promote local and systemic insulin resistance. Due to the continuing rise in obesity around the world, understanding how these ATMs contribute to metabolic disorders is of much interest.


RESULTS
Chemokines have been extensively studied for their role in ATM recruitment. Deficiency or antagonism of chemokine receptors that interact with multiple chemokine ligands reduces ATM accumulation. ATMs are now defined as either classically (M1) or alternatively (M2) activated. Peroxisome proliferator-activated receptor activation and adiponectin promote an M2-polarized state resulting in improved insulin sensitivity. Finally, recent studies have provided evidence that T lymphocytes, natural killer T cells, mast cells, and B cells also enter adipose tissue and may interact with macrophages and adipocytes.


CONCLUSIONS
Literature published during the past year has shown that macrophage recruitment to adipose tissue is only one of the important mediators of obesity-related insulin resistance. The phenotype of ATMs and recruitment of other immune cells to the adipose tissue play key roles in the overall contribution of adipose tissue to systemic metabolic outcomes of obesity.
Anderson
Emily K
EK
Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0615, USA.
Gutierrez
Dario A
DA
Hasty
Alyssa H
AH
D000273:Adipose Tissue / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007333:Insulin Resistance; D007962:Leukocytes / Q000378:metabolism* / Q000473:pathology; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D010641:Phenotype
D018836:Inflammation Mediators
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