Dr. Kevin Tracey

We were specifically addressing the question, might the brain, by sending signals through the vagus nerve, be turning off inflammation?

And that came about because of an experiment that produced a big surprise.

And you could call it an accident in the lab.

we were putting an anti-inflammatory molecule into the brains of mice and rats with the sole purpose of blocking inflammation in the brain in order to reduce the damage of a stroke, an experimental infarct.

And that all went as planned.

What we hadn't planned is that when we put the anti-inflammatory molecule in the brain, and we had developed this molecule in the lab, so it was an experimental drug, when we...

Put this in the brains of these animals, it also turned off inflammation in the body.

That was the holy shit moment.

Like, how could the brain be sending signals to control the immune system?

There was no way in 1998 to explain this.

We went into the literature.

And I found an old paper, then an old paper, now even older, that had been cited by essentially nobody, that Linda Watkins from Boulder, Colorado, had been studying sickness behavior.

And she showed that when she gave IL-1, a cytokine, of course, into the abdomen of animals, they develop sickness behavior, anorexia, fatigue, behavioral withdrawal, social withdrawal.

And when she cut the vagus nerve of those animals, it went away.

And so the only way to explain that was that the vagus nerve was sending signals up into the brain that was activating the sickness behavior networks behind it.

I got to thinking maybe when we had put this molecule in the brain of our animals, maybe we had discovered the motor arc of a reflex and Linda had discovered the sensory arc of the reflex.

And so I wrote a hypothesis paper, published it in Nature, called The Inflammatory Reflex.

And it turned out to be correct.

After 20 years of mechanistic work, we've connected all those dots.

Kelly is a remarkable human being who, as a teenager, was diagnosed with inflammatory bowel disease, Crohn's disease, which was devastating for her.