Research Articles
Mast cells, macrophages, and crown-like structures distinguish subcutaneous from visceral fat in mice

https://doi.org/10.1194/jlr.M011338Get rights and content
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Obesity is accompanied by adipocyte death and accumulation of macrophages and mast cells in expanding adipose tissues. Considering the differences in biological behavior of fat found in different anatomical locations, we explored the distribution of mast cells, solitary macrophages, and crown-like structures (CLS), the surrogates for dead adipocytes, in subcutaneous and abdominal visceral fat of lean and diet-induced obese C57BL/6 mice. In fat depots of lean mice, mast cells were far less prevalent than solitary macrophages. Subcutaneous fat contained more mast cells, but fewer solitary macrophages and CLS, than visceral fat. Whereas no significant change in mast cell density of subcutaneous fat was observed, obesity was accompanied by a substantial increase in mast cells in visceral fat. CLS became prevalent in visceral fat of obese mice, and the distribution paralleled mast cells. Adipose tissue mast cells contained and released preformed TNF-α, the cytokine implicated in the pathogenesis of obesity-linked insulin resistance. In summary, subcutaneous fat differed from visceral fat by immune cell composition and a lower prevalence of CLS both in lean and obese mice. The increase in mast cells in visceral fat of obese mice suggests their role in the pathogenesis of obesity and insulin resistance.

obesity
insulin resistance
adipose tissue inflammation
mast cell
adipose tissue macrophage
crown-like structure
tumor necrosis factor-α

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This work was supported by generous funds from the Katz Family Foundation.

    Abbreviations:

    ATM

    adipose tissue macrophages

    CLS

    crown-like structures

    DIO

    diet-induced obesity

    EAT

    epididymal adipose tissue

    HFD

    high-fat diet

    LFD

    low-fat diet

    MAT

    mesenteric adipose tissue

    PAT

    perinephric adipose tissue

    SAT

    subcutaneous adipose tissue

    TNF-α

    tumor necrosis factor α