Type 2 Diabetes and Lipoprotein Metabolism Affect LPS-Induced Cytokine and Chemokine Release in Primary Human Monocytes

Aims/Hypothesis: Obesity and insulin resistance are characterized by a chronic and low grade state of inflammation and the pro-inflammatory response of monocytes is affected in type 2 diabetes mellitus (T2D). We aimed to investigate whether LPS-induced monocytic cytokine and chemokine release depends on serum lipoprotein parameters in T2D patients. Methods: Primary human monocytes were isolated from 29 patients with known T2D and from 20 healthy volunteers. Anthropometric and disease-related parameters such as age, gender, BMI, WHR, diabetes duration, diabetes complications, and diabetes control (HbA1c) were documented. Monocytes were stimulated for 18h with LPS (1 mu g/ml). Unstimulated monocytes served as control. The supernatant concentrations of CCL2, CCL3, CCL4, CCL5, MIF and resistin were measured by ELISA. Results: LPS-stimulation significantly (p<0.001) increased CCL chemokine and resistin concentrations in healthy controls and in patients with T2D, whereas MIF release was not affected in both groups. LPS-induced CCL2 and resistin concentrations were significantly higher in T2D patients when compared to healthy controls. In T2D patients, LPS-induced CCL3 concentration was higher in males when compared to females (p=0.039) and supernatant resistin concentration upon stimulation with LPS showed a significant and positive correlation with age (r=0.6; p=0.001). LPS-induced CCL2 concentration was significantly and positively correlated with serum triglyceride concentration (r=0.4; p=0.009) in T2D patients. Furthermore, LPS-induced CCL4 concentration was significantly and positively correlated with total (r=0.4; p=0.035) and LDL cholesterol (r=0.4; p=0.033) concentration. Conclusions: LPS responsiveness of monocytes is altered in T2D and is affected by the respective serum lipoprotein metabolism.