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 18 h with LPS (1 μg/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.