June 8, 2022
Rheumatoid arthritis (RA) is the most common inflammatory disease of the joints. Nowadays, there are many therapies that can significantly reduce the symptoms However, bone loss and osteoporosis are still a problem. Most osteoporosis therapies aim to inhibit bone loss, while only a few therapies are able to actively promote the formation of new bone tissue to restore bone structure that has already been lost. Building on previous studies, researchers at the Leibniz Research Centre for Working Environment and Human Factors in Dortmund (IfADo) have taken a closer look at the role of the neurotransmitter dopamine in the bone metabolism of RA patients. They conclude that dopamine can be used for new therapeutic approaches to control bone loss in rheumatoid arthritis.
In a current project, Prof. Dr. Silvia Capellino’s group has investigated the importance of the biochemical messenger dopamine for the bone formation process in rheumatoid arthritis. Dopamine is a neurotransmitter of the central nervous system that controls movement, emotions, and cognition. Dopamine receptors, the receiving unit for signals through the neurotransmitter dopamine, were found in bone tissue.
The presence of dopamine receptors in RA patients suggests that dopamine also plays a role in the physiology of human bone metabolism. Therefore, the researchers hypothesised that the signalling pathway activated by dopamine in inflamed joints also influences bone metabolism in rheumatoid arthritis. From this, they deduced that deciphering these dopamine-regulated signalling pathways in bone metabolism may pave the way for new therapeutic approaches to control bone loss.
Background: Rheumatoid arthritis
Rheumatoid arthritis is an autoimmune disease characterised by chronic joint inflammation and subsequent joint destruction that can lead to complete loss of function. Furthermore, rheumatoid arthritis is not only a disease of the joints but can also affect many other organs and cause systemic osteoporosis, for example.
Current therapies target osteoclasts (bone cells responsible for reducing bone substance) to reduce bone loss. However, more treatment options would be needed to promote bone protection by directly acting on osteoblasts (bone cells responsible for building bone substance).
Schwendich, E.; Salinas Tejedor, L.; Schmitz, G.; Rickert, M.; Steinmeyer, J.; Rehart, S.; Tsiami, S.; Braun, J.; Baraliakos, X.; Reinders, J.; Neumann, E.; Müller-Ladner, U.; Capellino, S. Modulation of Dopamine Receptors on Osteoblasts as a Possible Therapeutic Strategy for Inducing Bone Formation in Arthritis. Cells 2022, 11, 1609. https://doi.org/10.3390/cells11101609