Relation of endothelial dysfunction and adipokines levels to insulin resistance in metabolic syndrome patients

Abstract

Obese metabolic syndrome (MS) patients were categorised into three groups: 44 with type 2 diabetes mellitus (T2DM)(D); 20 with T2DM and coronary artery disease (CAD) (DC), and 26 with MS alone (M). Eighteen healthy subjects were selected as controls (C). Insulin resistance (IR) was assessed by HOMA-IR. Adiponectin, tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and interleukin-8 (IL-8) concentrations were measured by xMAP technology. Endothelin-1 (ET-1) was determined by ELISA. We used laser Doppler imaging for evaluating cutaneous endothelium-dependent vasodilatation in the hand. D and DC groups had significantly elevated IR compared with M or C group (P < 0.01). TNF-α, IL-6, IL-8, MCP-1 and ET-1 levels in DC were significantly elevated compared with other groups (P < 0.001). IL-6, IL-8, MCP-1 and ET-1 in D group were higher than those in C group (P < 0.05). TNF-α, IL-6, IL-8, MCP-1 and ET-1 concentrations were correlated with HOMA-IR indexes and adiponectin levels. All patients had lower adiponectin concentrations than controls (P < 0.001), but there were no differences between the patient groups. Only D and DC groups demonstrated a significant and similar decrease in LDI-Ach marker compared to C group (P < 0.001). LDI-Ach values were significantly correlated with HOMA-IR indexes and adiponectin levels (P < 0.001). Our findings show that obese MS patients have significantly increased HOMA-IR, TNF-α, IL-6, MCP-1 and IL-8 levels, decreased adiponectin concentration, and endothelial dysfunction, but the presence of T2DM and CAD in these patients is associated with more pronounced endothelial dysfunction and increased production of inflammatory cytokines and chemokines.