Mind Your Body: Kill the Messenger

For years, rheumatoid arthritis left the patient, a Bosnian man, with crippling pain in his hands, wrists, elbows, and legs. Just eight weeks after a surgeon implanted a small device in his neck, the pain was alleviated and the man was again driving a delivery truck and performing manual labor. This new intervention is experimental, but it’s built on ideas that are increasingly mainstream.

“Immune cells and neurons seem to share a common language,” explains Valentin Pavlov, Ph.D., an investigator at the Feinstein Institute for Medical Research whose work, recently reported in Science, lays the foundation for the advance in treatment. In the past few years, researchers have begun to develop a clear picture of the connection between the nervous system and the immune system that will have a profound effect on how we understand and treat a wide variety of ills. Arthritis—a difficult-to-manage disease with inflammatory and auto-immune components—is an obvious target.

Some inflammation in response to injury is normal. When you stub a toe or burn a finger, it’s part of the body’s healing process. But sometimes the immune system overreacts and there is too much inflammation. In rheumatoid arthritis, immune cells collect in the body’s joints, causing pain and reduced mobility.

Normally, explains Pavlov, the multi-branched vagus nerve, which controls many automatic body functions such as heart rate, sends out signals that regulate inflammation. In a person suffering from arthritis, those signals misfire. Nobody is quite sure why. Unchecked inflammation is also implicated in heart disease, diabetes, depression, and digestive syndromes.

Drugs like ibuprofen reduce run-of-the-mill inflammation. But for a disease with runaway inflammation like arthritis, doctors’ standard plan of attack involves suppressing the immune system with a barrage of expensive, often toxic drugs that leave patients virtually unprotected from ordinary pathogens.

Implantation of the experimental device that rid the Bosnian subject of pain “is a direct method to restore the brakes on inflammation,” the surgical team reports. It represents the first clinical attempt to treat arthritis by electrically stimulating the vagus nerve without interfering with other organs. Further studies are exploring whether comparable results could be achieved less invasively—by stimulating branches of the vagus nerve in the ear, for example. Devices that target the vagus nerve are already FDA-approved for the treatment of epilepsy and depression, but years of testing will be needed before they are widely available for rheumatoid arthritis and related ailments.

In the meantime, scientists are closing in on how the nervous system and the immune system communicate—and just how effectively medicine can influence that conversation.