(Credit: Towfiqu Barbhuiya_
NEW HAVEN, Conn. — An epilepsy drug may soon find a new purpose in medicine — treating millions of patients dealing with osteoarthritis. Researchers from Yale have discovered that the medication carbamazepine also blocks a specific gene connected to joint degeneration.
In the United States alone, study authors estimate that nearly 30 million people are dealing with this common form of arthritis. The degenerative disease typically causes joint stiffness and pain, which can become debilitating for patients. Currently, the best treatments include pain relievers and exercise to reduce weight on the joints. However, these are not a cure for the progressive degeneration patients endure.
Yale’s Stephen G. Waxman notes that specialized proteins known as sodium channels can play a key role in our feelings of pain. These channels in the cell membranes produce electrical impulses inside “excitable” cells within muscles, the nervous system, and even the heart. Waxman identified one of these channels in particular, Nav1.7, as a key transmitter of pain signals.
The new study discovered that Nav1.7 is also present in “non-excitable” cells which help maintain our joint health and also produce collagen — a fiber-like protein which makes connective tissue. This was an important discovery since osteoarthritis results from the breakdown of cartilage between joints, typically in the hands, hips, and knees.
When researchers deleted Nav1.7 genes from collagen-producing cells, the change significantly slowed joint degeneration in mice with the disease. These experiments also found that carbamazepine, a sodium channel blocker used by epilepsy patients, provided strong protection against joint damage in these mice.
“The function of sodium channels in non-excitable cells has been a mystery,” Waxman says in a university release. “This new study provides a window on how small numbers of sodium channels can powerfully regulate the behavior of non-excitable cells.”
Wenyu Fu, a research scientist and first author of the study, adds that the discovery not only provides another treatment for arthritis patients but also opens up a new avenue of research that may create a cure for the condition in the future.
The findings are published in the journal Nature.
