Increased Toll-Like Receptor (TLR) Activation and TLR Ligands in Recently Diagnosed Type 2 Diabetic Subjects

• Published in: Diabetes care Vol. 33; no. 4; pp. 861 - 868
• Main Authors: Dasu, Mohan R, Devaraj, Sridevi, Park, Samuel, Jialal, Ishwarlal
• Format: Journal Article
• Language: English
• Published: United States American Diabetes Association 01.04.2010
• Subjects: Adapter proteins; Adaptor Proteins, Vesicular Transport; Adaptor Proteins, Vesicular Transport - metabolism; Atherosclerosis; Blotting, Western; body mass index; Case-Control Studies; Chaperonin 60; Chaperonin 60 - metabolism; Chronic illnesses; correlation; Diabetes; Diabetes Mellitus, Type 2; Diabetes Mellitus, Type 2 - metabolism; E coli; Enzyme-Linked Immunosorbent Assay; flow cytometry; free fatty acids; genetics; glucose; HMGB1 Protein; HMGB1 Protein - metabolism; homeostasis; HSP72 Heat-Shock Proteins; HSP72 Heat-Shock Proteins - metabolism; Human subjects; Humans; Hyaluronic Acid; Hyaluronic Acid - metabolism; Hyperglycemia; Immune system; Immunoprecipitation; Inflammation; Insulin resistance; Interferon Regulatory Factor-3; Interferon Regulatory Factor-3 - metabolism; Interferon-gamma; Interferon-gamma - metabolism; interferons; Interleukin-1 Receptor-Associated Kinases; Interleukin-1 Receptor-Associated Kinases - metabolism; Interleukin-1beta; Interleukin-1beta - metabolism; interleukins; lysine; Messenger RNA; metabolism; Molecular weight; monocytes; Monocytes - metabolism; Myeloid Differentiation Factor 88; Myeloid Differentiation Factor 88 - metabolism; noninsulin-dependent diabetes mellitus; Original Research; patients; protein synthesis; receptors; Reverse Transcriptase Polymerase Chain Reaction; Rheumatoid arthritis; risk; Sample size; Studies; Toll-Like Receptor 2; Toll-Like Receptor 2 - genetics; Toll-Like Receptor 2 - metabolism; Toll-Like Receptor 4; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 4 - metabolism; Toll-Like Receptors; Toll-Like Receptors - genetics; Toll-Like Receptors - metabolism; Transcription Factor RelA; Transcription Factor RelA - metabolism; Type 2 diabetes; Western blotting
• ISSN: 0149-5992; 1935-5548; 1935-5548
• DOI: 10.2337/dc09-1799

OBJECTIVE: Individuals with type 2 diabetes have a myriad of metabolic aberrations including increased inflammation, increasing their cardiovascular risk. Toll-like receptors (TLRs) and their ligands play a key role in insulin resistance and atherosclerosis. However, there is a paucity of data examining the expression and activity of TLRs in type 2 diabetes. Thus, in the present study, we examined TLR2 and TLR4 mRNA and protein expression, their ligands, and signaling in monocytes of recently diagnosed type 2 diabetic patients. RESEARCH DESIGN AND METHODS: TLR mRNA, protein expression, TLR ligands, and TLR signaling were measured in freshly isolated monocytes from healthy human control subjects (n = 23) and type 2 diabetic subjects (n = 23) using real-time RT-PCR, Western blot, and flow cytometric assays. RESULTS: Type 2 diabetic subjects had significantly increased TLR2, TLR4 mRNA, and protein in monocytes compared with control subjects (P < 0.05). Increased TLR2 and TLR4 expression correlated with BMI, homeostasis model assessment-insulin resistance (HOMA-IR), glucose, A1C, Nε-(carboxymethyl) lysine (CML), and free fatty acid (FFA). Ligands of TLR2 and TLR4, namely, HSP60, HSP70, HMGB1, endotoxin, and hyaluronan levels, were elevated in type 2 diabetic subjects and positively correlated with TLR2 and TLR4. Type 2 diabetic subjects showed increased MyD88, phosphorylated IRAK-1, Trif, TICAM-1, IRF-3, and NF-κB p65 expression in monocytes compared with control subjects. Furthermore, TLR-MyD88-NF-κB signaling resulted in elevated levels of cytokines (P < 0.05), but increased interleukin (IL)-1β, interferon (IFN)-γ, and endotoxin were not significant when adjusted for BMI. CONCLUSIONS: In this comprehensive study, we make the novel observation that TLR2 and TLR4 expression and their ligands, signaling, and functional activation are increased in recently diagnosed type 2 diabetes and contribute to the proinflammatory state.