Macrophage content in subcutaneous adipose tissue: associations with adiposity, age, inflammatory markers, and whole-body insulin action in healthy Pima Indians.

Description

This study examined in a healthy nondiabetic population (n=41 men and 25 women) the associations between accumulation and activation of macrophages in subcutaneous adipose tissue and insulin resistance. Adipose tissue macrophage content (ATMc) was correlated with percent body fat, age and female sex. There were negative correlations between glucose disposal and gene expression of CD68, CD11b and CSF1R that were not independent from percent body fat, age and sex. However, there were associations between markers produced by macrophages (plasminogen activator inhibitor-1 and CD11 antigen-like family member C) and glucose disposal rate after adjusting for the same covariates. In this sample of healthy men and women, subcutaneous ATMc was related to age and adiposity but not to insulin action, indicating that ATMc per se is not a direct cause of insulin resistance. This paper was accompanied by an excellent editorial by William T. Cefalu, in which he gave some historical background on the inflammation story, going back as far as 2,000 years ago. More recently, in the fifties, clinical observations suggested that aspirin in diabetic subjects was associated with improvements in glucose levels. However, he raised the point that because insulin action was not well understood at the time, the role of inflammation in the insulin resistance process did not receive a lot of attention from the medical and research communities. Nowadays, the focus on inflammation, insulin resistance and diabetes is a field that is going “Back to the Future”.