The Expression Of TLR4 Signal Associated With Macrovascular Injury On Peripheral Mononuclear Cells In Type2 Diabetic Patients

Objectives: To investigate the role of toll like receptor 4(TLR4)in free fatty acid induced macrovascular injury in patients with type 2 diabetes mellitus, and to investigate the role of TLR4 pathway and osteocalcin in the pathogenesis of macrovascular injury in type 2 diabetes mellitus(T2DM)Methods: A total of 66 patients with T2 DM were enrolled from Endocrinology of Gansu Provincial Hospital between March 2014 and June 2014. All the patients were classified into two groups based on the value of carotid intima-media thickness(IMT), T2 DM without macrovascular injury group(IMT<0.9mm, 20 subjects) and T2 DM with macrovascular injury group(IMT≥0.9mm, or IMT<0.9mm but with plaques, 46 subjects), 40 gender and age matched healthy subjects were used as the control group. The serum levels of fasting blood glucose, lipids, insulin, glycosylated hemoglobin A1 c, Free fatty acid(FFA), high-sensitivity c-reactive protein(hs-CRP), interleukin-6(IL-6),monocyte chemotactic protein-1(MCP-1) and osteocalcin(BGP) were tested. The level of TLR4 protein expression on peripheral blood monocyte cells(PBMCs)was detected using flow cytometry(FCM).Results: The level of TLR4 in T2 DM with macrovascular injury group was markedly higher than that in both the T2 DM without macrovascular injury group and the control group(F=25.9, P<0.05). While the level of BGP in T2 DM with macrovascular injury group was significantly decreased as compared to that in T2 DM without macrovascular injury group and the control group(F=8.39, P<0.05). In addition, the levels of FFA, MCP-1, hs-CRP and IL-6 were increased in T2 DM with macrovascular injury group compared with that in control group(all P<0.05). Pearson linear analysis showed that IMT was positively correlated with TLR4, FFA, MCP-1, hs-CRP and IL-6 levels(r=0.540, 0.295, 0.329, 0.271, 0.244, respectively, All P<0.05), but negatively correlated with BGP(r=-0.274, P<0.05). TLR4 level was positively correlated with FFA, MCP-1, hs-CRP and IL-6(r=0.266, 0.385, 0.246, 0.214, respectively P<0.05), while negatively correlated with BGP level(r=-0.227, P<0.05). Multivariate linear stepwise regression analysis showed that TLR4, Age, FBG and osteocalcin are the independent risk factors for IMT in patients with type 2 diabetes.Conclusions: TLR4 signaling pathway involved in the pathogenesis of macrovascular injury induced by FFA in T2 DM. Osteocalcin is the protective factor for macrovascular injury in T2 DM and negatively correlated to TLR4.