Can Zapping the Vagus Nerve Jump-Start Immunity?

Douglas Fox in Scientific American:

Six times a day, Katrin pauses whatever she's doing, removes a small magnet from her pocket and touches it to a raised patch of skin just below her collar bone. For 60 seconds, she feels a soft vibration in her throat. Her voice quavers if she talks. Then, the sensation subsides. The magnet switches on an implanted device that emits a series of electrical pulses — each about a milliamp, similar to the current drawn by a typical hearing aid. These pulses stimulate her vagus nerve, a tract of fibres that runs down the neck from the brainstem to several major organs, including the heart and gut. The technique, called vagus-nerve stimulation, has been used since the 1990s to treat epilepsy, and since the early 2000s to treat depression. But Katrin, a 70-year-old fitness instructor in Amsterdam, who asked that her name be changed for this story, uses it to control rheumatoid arthritis, an autoimmune disorder that results in the destruction of cartilage around joints and other tissues. A clinical trial in which she enrolled five years ago is the first of its kind in humans, and it represents the culmination of two decades of research looking into the connection between the nervous and immune systems.

For Kevin Tracey, a neurosurgeon at the Feinstein Institute for Medical Research in Manhasset, New York, the vagus nerve is a major component of that connection, and he says that electrical stimulation could represent a better way to treat autoimmune diseases, such as lupus, Crohn's disease and more. Several pharmaceutical companies are investing in 'electroceuticals' — devices that can modulate nerves — to treat cardiovascular and metabolic diseases. But Tracey's goal of controlling inflammation with such a device would represent a major leap forward, if it succeeds. He is a pioneer who “got a lot of people onboard and doing research in this area”, says Dianne Lorton, a neuroscientist at Kent State University in Ohio, who has spent 30 years studying nerves that infiltrate immune organs such as the lymph nodes and spleen. But she and other observers caution that the neural circuits underlying anti-inflammatory effects are not yet well understood. Tracey acknowledges this criticism, but still sees huge potential in electrical stimulation. “In our lifetime, we will see devices replacing some drugs,” he says. Delivering shocks to the vagus or other peripheral nerves could provide treatment for a host of diseases, he argues, from diabetes to high blood pressure and bleeding. “This is the beginning of a field.”

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