Artikel
The influence of Substance P and α CGRP on articular chondrocytes from osteoarthritic patients
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Veröffentlicht: | 23. Oktober 2017 |
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Gliederung
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Objectives: Osteoarthritis (OA), a degenerative, slowly progressive synovial joint disease, represents the leading cause of disability and chronic pain in the elderly. OA is a failure of all joint tissues, including the articular cartilage and the subchondral bone, and is initiated by multiple risk factors. To date pharmacological interventions can only relieve pain, whilst cell- and compound based therapies have limited success in the regeneration of damaged tissues. Thus, there is a need for identification of novel targets for diagnostic and therapeutic approaches to improve the treatment and life quality of OA patients. The joints are innervated by calcitonin gene-related peptide (αCGRP) - and substance P (SP) positive sensory nerve fibers which are a potential source of tibial-femoral pain during OA pathogenesis. Alteration of sensory joint innervation might be partly responsible for degenerative changes which contribute to development of OA. We therefore aim to analyze the detailed effects of SP and αCGRP on the metabolism of articular chondrocytes of OA patients.
Methods: Chondrocytes, isolated from human articular cartilage which was collected from surgically removed joints of patients undergoing total knee replacements due to OA, were expanded for 1 passage and stimulated with SP or αCGRP (10-8M and 10-10M) in 2D- and 3D-cell culture systems. Subsequently, proliferation of stimulated cells was analyzed via BrdU assay, apoptosis via Caspase 3/7 assay, adhesion ability with crystal violet staining, gene expression of different marker genes with qPCR and activation of signaling pathways with western blot and ELISA.
Results and Conclusion: Stimulation with SP in a concentration of 10-10M resulted in an increase in apoptosis and a decrease in adhesion, whereas stimulation with a higher SP concentration (10-8M) enhanced the gene expression of the pro-inflammatory genes TNFα and IL-6 significantly and IL-1 by trend. αCGRP accelerated in both concentrations (10-8M and 10-10M) the growth rate of chondrocytes and diminished the adhesion ability of the cells on cell culture plastic surface, but also increased the apoptosis rate when applied in a high concentration (10-8M). Chondrocytes moreover increased intracellular cAMP- level after short-term stimulation with αCGRP and induced phosphorylation of ERK1/2 after short-term stimulation with both neuropeptides, SP and αCGRP, in both concentrations.
We conclude for both neurotransmitters dose-dependent effects on chondrocytes. SP exerted a rather catabolic influence on the cells by inducing the expression of pro-inflammatory genes and apoptosis, whereas αCGRP affected the cells in an anabolic manner by enhancing proliferation. These different effects of SP and αCGRP seemed to be at least in part, mediated via the same signalling pathways (ERK1/2), whereby αCGRP induced in addition a cAMP increase in the cells. The exact determination of all involved signalling pathways and there common interactions are a focus of investigation.