There are at least as many bacterial cells in your body as their human cells. And there’s a growing recognition that they’re critical for everything from digestion to mental health. They also play a big role in immunity – our ability to fight off diseases. But the relationship isn’t always easy or friendly. For all the good they do, if gut bacteria get into the wrong places, it can be problematic.
Lora Hooper, a professor of immunology at University of Texas Southwestern Medical Center, describes our relationship with bacteria in terms of a war of containment. We need them. But they could kill us, or at least make us very sick, if they escaped into our bodies. So, our intestine is lined with a "demilitarized zone" that traps or kills bacteria.
And, yet, somehow, biochemical messages can, and do, penetrate this layer and travel to far-flung parts of the body, including the brain.
Just how all this works isn't clear. There may be as many questions as answers. And that's exactly what drives Hooper's work.