engleski

7-ketocholesterol binds toll-like receptor 4 on synovial tissue macrophages of patients with osteoarthritis and supports domination of M1 chemokine production

Introduction: We hypothesized that the oxidized lipid derivative, 7-ketocholesterol (7-KC), represents a danger signal in the synovial membrane of patients with osteoarthritis (OA). The aim was to investigate the influence of 7-KC on chemokine production in synovial tissue CD68+ macrophages of patients with OA in respect of lipopolysaccharide (LPS) stimulation, the prototypic M1 polarization stimulus. Material and methods: Double immunofluorescence and immunohistology were performed in paraffin-embedded synovial tissue sections, which were obtained during the knee alloarthroplasty. Synovial mononuclear cells were isolated by enzymatic digestion. We analyzed the binding of 7-KC for Toll-like receptor (TLR)-4 and the viability of CD68+ cells, intracellular chemokine expression in 18 hour-stimulated CD68+ cells with 7-KC, 7-KC+LPS, LPS or medium only, using flow cytometry. Results: 7-KC bound for TLR-4 on CD68+ cells, in a dose-dependent manner (3, 125 M -25 M) and nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB)+CD68+ cells were found in synovial tissue. The increasing concentrations of 7-KC proportionally killed CD68+ cells in vitro and apoptotic protease activating factor (APAF)-1+CD68+ cells were sparse in synovial tissue. 7-KC and LPS independently increased expression of CC ligand (CCL)3, however, 7-KC increased CCL2 only in combination with LPS. Contrary to LPS, 7-KC decreased the frequency of CCL22, although both of them independently decreased frequency of CCL17 within the CD68+ population. Conclusions: 7-KC binds to TLR-4 in a dose-dependent manner and in pharmacological dose supports type 1 macrophage chemokine production, followed by CD68+ cell-apoptosis in vitro.

7-ketocholesterol ; toll-like receptor 4 ; synovial tissue ; macrophages ; osteoarthritis

nije evidentirano