Published in:
01-02-2010 | Article
Inflammation in subcutaneous adipose tissue: relationship to adipose cell size
Published in: Diabetologia | Issue 2/2010
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Aims/hypothesis
Inflammation is associated with increased body mass and purportedly with increased size of adipose cells. We sought to determine whether increased size of adipose cells is associated with localised inflammation in weight-stable, moderately obese humans.
Methods
We recruited 49 healthy, moderately obese individuals for quantification of insulin resistance (modified insulin suppression test) and subcutaneous abdominal adipose tissue biopsy. Cell size distribution was analysed with a multisizer device and inflammatory gene expression with real-time PCR. Correlations between inflammatory gene expression and cell size variables, with adjustment for sex and insulin resistance, were calculated.
Results
Adipose cells were bimodally distributed, with 47% in a ‘large’ cell population and the remainder in a ‘small’ cell population. The median diameter of the large adipose cells was not associated with expression of inflammatory genes. Rather, the fraction of small adipose cells was consistently associated with inflammatory gene expression, independently of sex, insulin resistance and BMI. This association was more pronounced in insulin-resistant than insulin-sensitive individuals. Insulin resistance also independently predicted expression of inflammatory genes.
Conclusions/interpretation
This study demonstrates that among moderately obese, weight-stable individuals an increased proportion of small adipose cells is associated with inflammation in subcutaneous adipose tissue, whereas size of mature adipose cells is not. The observed association between small adipose cells and inflammation may reflect impaired adipogenesis and/or terminal differentiation. However, it is unclear whether this is a cause or consequence of inflammation. This question and whether small vs large adipose cells contribute differently to inflammation in adipose tissue are topics for future research.
Trial registration: ClinicalTrials.gov NCT00285844
Funding: National Institutes of Health/ National Institute of Diabetes and Digestive and Kidney Diseases 1 R01 DK071309-01, 5RO1DK071333, 5K23 RR16071, Clinical and Translational Science Award 1UL1 RR025744, and the National Institute of Diabetes and Digestive and Kidney Diseases Intramural Research Program.