TLR4 and Caveolin-1 in Monocytes Are Associated With Inflammatory Conditions in Diabetic Neuropathy

The purpose of this study was to investigate the expression of TLR4 and caveolin-1 in monocytes among healthy volunteers as well as those with type-2 diabetes mellitus (T2DM) and diabetic peripheral neuropathy (DPN). Nineteen healthy control subjects, 18 patients with T2DM, and 20 patients with DPN were enrolled. Toll-like receptor (TLR)4, caveolin-1, MyD88, phosphorylated IκB, and plasma TNF-α and interleukin (IL)-6 were measured using real-time polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. Compared with the other two groups, the DPN group had higher expression of TLR4, MyD88, phosphorylated IκB, TNF-α, and IL-6, but significantly lower levels of caveolin-1 and total IκB in monocytes. Plasma concentrations of TNF-α and IL-6 were positively correlated with TLR4 and negatively correlated with caveolin-1 in patients with DPN. Plasma concentration of TLR4 was negatively correlated with caveolin-1 in patients with DPN. Reduced expression of caveolin-1 in monocytes could aggravate the TLR4-mediated inflammatory cascade.