Endosomal Toll-Like Receptor Status in Patients with Metabolic Syndrome

Background: Metabolic syndrome (MetS) predisposes to both diabetes and cardiovascular disease, and inflammation is pivotal in MetS. The Toll-like receptors (TLRs), TLR2 and TLR4, are implicated in both diabetes and atherosclerosis, are increased in MetS, and contribute to the inflammatory burden. Recent studies also suggest an evolving role of endosomal TLRs in diabetic complications. However, there is a paucity of data with regard to the expression of endosomal TLRs such as TLR3, 7-9 in MetS. Aim: Thus, in this short report, we examine expression of monocytes TLR3 and TLR9 in our cohort of subjects with nascent MetS compared to matched controls. Subjects and Methods: Monocytes were isolated from subjects with MetS (n=45) and matched controls (n=37), respectively, and TLR3 and TLR9 expression was assessed by intracellular flow cytometry and correlated with nuclear factor (NF)-κB expression. Results: We demonstrate increased endosomal TLR9 expression in MetS compared to controls that correlate with increased nuclear NF-κB expression in the monocytes of these subjects, with no change in TLR3 protein. Conclusion: Future studies are required to confirm these findings and determine the role of TLR9 in the increased cardiovascular risk in MetS.