More than eight million Britons are affected by osteoarthritis (OA), many of them forced to deal with severe pain on a daily basis. The disease also puts a heavy strain on the healthcare system, with almost £200 million spent annually by the NHS on joint replacement procedures. But many OA sufferers are elderly people and surgery may not always be the best option. Researchers from the University of Nottingham are hoping that their new discovery will lead to the development of safe, effective treatments for OA pain.
At present, pain relief solutions for OA patients include steroid injections and non-steroidal anti-inflammatory drugs. They work by reducing inflammation but some of them cause serious side effects, meaning that their use is limited.
The team at the university´s Arthritis Research UK Pain Centre focused on a protein called TRPV1. It is the product of human nerve cells that are responsive to pain and previous research has indicated that TRPV1 may play an important role in OA pain. This means that drugs which block the protein (so-called TRPV1 antagonists) could be used to reduce pain.
Dr Sara Kelly, one of the lead researchers, said that recently conducted clinical trials showed TRPV1 antagonists to have an adverse effect on body temperature. More specifically, they were found to cause hyperthermia – the medical term for overheating. The Nottingham research team set out to establish whether this side effect could be eliminated by blocking TRPV1 locally. Their experiments with rats showed that direct injection of TRPV1 antagonists into the affected joint produced the desired result: the pain was reduced without hyperthermia becoming an issue. The next step would be to test this approach with human subjects.