Co-operative evolution of the immune system in humans?

image from Lee and Mazmanian, from Caltech, published this great review in Science on microbes in the gut and how different bacteria might have been involved in the evolution of the human immune system.

Link (subscription required): Has the Microbiota Played a Critical Role in the Evolution of the Adaptive Immune System? by Yun Kyung Lee and Sarkis K. Mazmanian

They discuss research that shows different bacteria modulating the maturation and function of different types of T-cells. And this modulation not only affects what happens immunologically in the gut, but also the rest of the body.

The thought is that this modulation not only keeps the body from rejecting the bacteria outright, but also might provide a protective environment favoring that bacteria, including keeping out other competing bacteria. They also suggest some potential connection with auto-immunity as well.

How cool is that?

Of course, all this requires a proper balance of bacterial populations and T-cell modulation – any imbalance can lead to disease. Indeed, they use the term “pathobionts” for bacteria that normally colonize the gut without adverse affects, but still remain pathogenic under certain circumstances.

There has been lots of research in understanding the molecular mechanisms that underly our relationship as host to a whole ecosystem of bacteria in and on our body. This review provides a great overview of what’s known about the potential modulation of the evolution of our immunity. It’s worth a read if you can get the paper.

Image from striatic