The high serum monocyte chemoattractant protein-1 in obesity is influenced by high parathyroid hormone and not adiposity

Context: Chronic high levels of PTH may be associated with up-regulation of proteases and cytokines. Monocyte chemoattractant protein-1 (MCP-1) is an inflammatory cytokine, produced predominantly by macrophages and endothelial cells, and is expressed in adipose tissue. More recently it has been shown that PTH administration increases MCP-1 expression in osteoblasts. Objectives: Because both PTH and MCP-1 levels are higher in obesity, the goal was to determine whether the high MCP-1 occurs only in the presence of high serum PTH and is independent of adiposity and examine its relationship with bone mineral density (BMD) and turnover. Design, Setting, and Participants: In this case-control clinical design, 111 eligible women were categorized into four groups: leaner women [body mass index (BMI) 23 ± 2 kg/m²] with normal or higher PTH and obese (BMI 44 ± 7 kg/m²) with normal or higher PTH. Results: Serum MCP-1 levels were higher (P < 0.01) in the high (PTH = 74.9 ± 27.0 pg/ml, MCP-1 =421.5 ± 157.0 pg/ml) compared with normal PTH (PTH = 32.5 ± 10.4 pg/ml, MCP-1 =322.5 ± 97.8 pg/ml) group, independent of BMI. C-reactive protein and adiponectin were influenced only by BMI and not PTH. MCP-1 was positively associated with osteocalcin and propeptide of type 1 collagen in the leaner (r > 0.3, P < 0.05) but not the obese women and was not associated with BMD in either group. Conclusions: Together these data suggest that MCP-1 is higher only in the presence of increased PTH and that adiposity alone cannot explain the higher MCP-1 levels in obesity.