Microbes caused discomfort in mice by activating nervous system, not immune response
Bacteria can directly trigger the nerves that sense pain, suggesting that the body’s own immune reaction is not always to blame for the extra tenderness of an infected wound. In fact, mice with staph-infected paws showed signs of pain even before immune cells had time to arrive at the site, researchers report online August 21 in Nature.
“Most people think that when they get pain during infection it’s due to the immune system,” says coauthor Isaac Chiu of Boston Children’s Hospital and Harvard Medical School. Indeed, immune cells do release pain-causing molecules while fighting off invading microbes. But in recent years scientists have started uncovering evidence that bacteria can also cause pain.
Chiu and his colleagues stumbled on this idea when they grew immune cells and pain-sensing cells together in a dish. The researchers were trying to activate the immune cells by adding bacteria to the mix but were surprised to see an