Association of monocyte CCR2 expression with obesity and insulin resistance in postmenopausal women

Monocytes actively participate in inflammatory mechanisms that contribute to the development of adipose tissue dysfunction and atherogenesis. The aim of this study was to evaluate the association of monocyte CCR2 chemokine receptor expression and intracellular oxidative burst with the metabolic and inflammatory factors related to body weight.

The study was performed in 67 postmenopausal women with normal, overweight and obese body mass index. Monocyte CCR2 surface expression and intracellular oxidative burst activity (determined using 2', 7'-dichlorofluorescin diacetate) were analyzed by flow cytometry. Serum levels of HMW adoponectin, monocyte chemoattractant protein-1 (MCP-1), insulin, glucose, lipids and C-reactive protein were determined.

Subjects with homeostasis model assessment-estimated insulin resistance (HOMA-IR) above the median had significantly higher proportion of CCR2+ monocytes and higher mean fluorescence intensity (MFI) of CCR2 and oxidative burst. The proportion of CCR2+ monocytes and CCR2 MFI were correlated with body weight, body mass index, fat mass, insulin and HOMA-IR. Oxidative burst also correlated with anthropometric measures, fat mass and expression of CCR2. No correlations were found between these markers of monocyte activation and HMW adiponectin or monocyte chemoattractant protein-1. The absolute number of monocytes was associated with insulin and this association remained significant after adjusting for C-reactive protein. In the multiple regression model the monocyte number was determined to be an independent predictor of insulin level.

These results provide support for significant associations of monocyte number and markers involved in monocyte activation with obesity and insulin resistance.