Scientists at Johns Hopkins have uncovered an important link between getting specific bacterial infections and developing autoimmune diseases such as arthritis. This occurs when the cells are stressed by exposure to irradiation, environmental toxins or the body's stress chemicals. The study also offers a starting place for scientists to investigate environmental or genetic triggers to autoimmune diseases. The team focused on infections by Salmonella, bacteria well known for food poisoning but also long thought to trigger arthritis in some people. But a smaller, significant number of those patients get a severe, debilitating type of arthritis that's long-lasting.
Cells invaded by bacteria normally give clear signals that they're infected.
But CTLs also went into attack mode if the cells displayed a piece of the mouse's own housekeeping molecule or the identical human version. That's a huge immune response. Based on the similarity of the set-up in humans, he adds, the response is likely the same. Now the scientists are trying to find why and how this immune response translates into arthritis in some mice and humans. In a small side study, the team also found that normal, uninfected body cells could be attacked by CTLs if the cells were stressed in some way, such as being exposed to higher temperature or radiation or general infection.