When Good Germs Go Bad - Friendly Bacteria Triggers Arthritis in Mice

Saw a really interesting article in Scientific American about a study regarding a link between a specific strain of bacteria and rheumatoid arthritis (RA) in mice. The study found that the introduction of a single type of bacteria could increase the amount of IL-17 (interleukin 17), a protein that signals the immune system to cause inflammation, in the mouse. The "friendly" bacteria that causes this accelerated the onset of arthritis in the mice. The mice were selected to already be genetically predisposed to having arthritis, so all mice in the study developed arthritis. But the mice that were given the bacteria developed RA much more quickly.

Why is this important? This could mean that exposure to even a single bacteria or virus could trigger an autoimmune reaction in genetically susceptible individuals. Here's an excerpt:

Mathis emphasized that one should not take away from these mouse studies "that mice or humans can 'catch' an autoimmune disease or arthritis," she says. She added that the better way to think about it is that individuals have varying degrees of genetic susceptibility, and when exposed to certain environmental factors may then go on to develop disease. "It's really an interaction between genetics and environment," Mathis says.

Crohn's Disease or Inflammatory Bowel Disease (IBD) may have a similar pattern to RA. It could also mean that there is a single bacteria or virus responsible for the disease. Or ... it could also mean that there are any number of bacteria or viruses that trigger the disease. Either way, it's a very study and reinforces previous theories and studies I've seen.