Objective: Accumulation of adipose tissue macrophages (ATMs) is observed in obesity and may participate in the development of insulin resistance and obesity-related complications. The aim of our study was to investigate the effect of long-term dietary intervention on ATM content in human adipose tissue.
Design: We performed a multi-phase longitudinal study.
Subjects and measurements: A total of 27 obese pre-menopausal women (age 39 ± 2 years, body mass index 33.7 ± 0.5 kg m(-2)) underwent a 6-month dietary intervention consisting of two periods: 4 weeks of very low-calorie diet (VLCD) followed by weight stabilization composed of 2 months of low-calorie diet and 3 to 4 months of weight maintenance diet. At baseline and at the end of each dietary period, samples of subcutaneous adipose tissue (SAT) were obtained by needle biopsy and blood samples were drawn. ATMs were determined by flow cytometry using combinations of cell surface markers. Selected cytokine and chemokine plasma levels were measured using enzyme-linked immunosorbent assay. In addition, in a subgroup of 16 subjects, gene expression profiling of macrophage markers in SAT was performed using real-time PCR.
Results: Dietary intervention led to a significant decrease in body weight, plasma insulin and C-reactive protein levels. After VLCD, ATM content defined by CD45+/14+/206+ did not change, whereas it decreased at the end of the intervention. This decrease was associated with a downregulation of macrophage marker mRNA levels (CD14, CD163, CD68 and LYVE-1 (lymphatic vessel endothelial hyaluronan receptor-1)) and plasma levels of monocyte-chemoattractant protein-1 (MCP-1) and CXCL5 (chemokine (C-X-C motif) ligand 5). During the whole dietary intervention, the proportion of two ATM subpopulations distinguished by the CD16 marker was not changed.
Conclusion: A 6-month weight-reducing dietary intervention, but not VLCD, promotes a decrease in the number of the whole ATM population with no change in the relative distribution of ATM subsets.