Calcitonin Gene-Related Peptide Modulates the Production of Pro-Inflammatory Cytokines Associated with Periprosthetic Osteolysis by THP-1 Macrophage-Like Cells

摘要

Objective: An anti-resorptive impact of the neuropeptide calcitonin gene-related peptide (CGRP) on periprosthetic osteolysis, the leading cause of early prosthesis loosening, has been shown previously. In this study, the impact of CGRP on pro-inflammatory cytokine production associated with periprosthetic osteolysis was analysed using THP-1 macrophage-like cells. Methods: Cells were stimulated with ultra-high-molecular-weight polyethylene (UHMWPE) particles (cell-to-particle ratios of 1:100 and 1:500) and lipopolysaccharides (LPS; 1 mu g/ml) to establish osteolytic conditions, and simultaneously treated with CGRP (10(-8) M). Receptor activator of nuclear factor-kappa B (RANK), RANK ligand (RANKL) and tumour necrosis factor (TNF)-alpha mRNA expression were measured by quantitative RT-PCR. RANK protein was detected by Western blot. Secreted protein levels of TNF-alpha as well as interleukin (IL)-1 beta and IL-6 were quantified in cell culture supernatants by ELISA and Bio-Plex cytokine assay, respectively. Results: Activation of macrophage-like cells failed to enhance the production of RANK but led to a dose- and time-dependent increase of TNF-alpha mRNA and secreted protein levels of TNF-alpha, IL-1 beta and IL-6. Application of CGRP time-dependently suppressed TNF-alpha mRNA expression induced by low-particle concentrations and LPS, while both particle-and LPS-induced secretion of TNF-alpha was inhibited. A pronounced inhibitory effect of CGRP on LPS-induced cytokine production at 24 h of incubation was also observed with IL-1 beta and IL-6. Conclusions: CGRP shows a time-dependent inhibitory effect on the secretion of osteolysis- associated pro-inflammatory cytokines, indicating an indirect anti-resorptive influence of the neuropeptide on both aseptic prosthesis loosening and bacterially induced bone resorption which might enhance the life time of total joint replacements. (C) 2014 S. Karger AG, Basel