Chronic Pain And Itch Blocked Simultaneously With Discovery Of New Antibody
Duke University researchers have discovered an antibody that blocks sensations of itch and pain in mice, a new study reports, opening doors for conditional relief that doesn’t involve potentially addictive opioids.
To relieve deep, unreachable sensations of pain and itch, such as those found in contact dermatitis and fibromyalgia, physicians commonly turn to powerful drugs. While these drugs offer blanket treatment, dulling pain and reducing itching, they carry a high risk as well. Many people do not go on to develop an addiction, according to certain research, but the variance in both dosage and patient profile make them risky in the aggregate.
Duke researchers may have discovered a way to avoid pain pills altogether, thanks to voltage-sensitive sodium channels in the cells’ membranes. These channels open or close depending on the electric signal emitted by the cell. And one in particular, called the Nav1.7 subtype, is responsible for sensing pain.
"Originally, I was interested in isolating these sodium channels from cells to study their structure," said lead researcher Seok-Yong Lee, assistant professor of biochemistry in the Duke University Medical School, in a statement. "But then I thought, what if I could make an antibody that interferes with the channel function?"
Lee and his colleagues set to work on testing the antibody in cultured cells that had been engineered to express the Nav1.7 sodium channel. They found that the antibody can bind to the channel and stabilize its closed state. Ultimately, this leads to less sensitivity to pain.
But they wanted to take the study out of simple cell models and find out what would happen in live animals, who were bred to experience neuropathic and inflammatory pain. When the team bound the same antibodies to the sodium channels, their results mirrored the earlier experiments. Mice that had experienced pain no longer did, and those that had been given the antibody showed no dependence to it once it was removed.
"Now we have a compound that can potentially treat both pain and itch at the same time," said Lee, whose team is the first to show Nav1.7 sodium channels play a regulatory role in feelings of itch.
In the U.S. alone, chronic pain and itch afflict some five million adults in the form of fibromyalgia — a disorder of unknown origin that produces stiffness, deep itching, and thinking problems. Contact dermatitis, a condition produced by either irritants or allergic reaction, afflicts upward of 10 million. Sufferers often report unending itchiness, often in places “deep in the skin,” where they can’t actually scratch.
"We hope our discovery will garner interest from pharmaceutical companies that can help us expand our studies into clinical trials," Lee said. Currently, he and his colleagues are at work in securing a patent on the antibody, which hopefully reaches the mainstream to avoid the need for opioids in treating chronic pain.
Source: Lee JH, Park CK, Chen G, et al. A monoclonal antibody that targets a Nav1.7 channel voltage sensor for pain and itch relief. Cell. 2014.