Triggering autoimmune assaults
Mouth bacteria unleash inflammation-inducing protein
By Janet Raloff
SAN DIEGO — Our bodies provide food and shelter for trillions of microbes — bacteria, yeasts and other squatters. Now, researchers report that a few resident species release a substance that can inappropriately rev up the immune system. If this happens at the wrong time, animal tests suggest, the body may launch a dangerous assault against itself.
Once such an autoimmune attack begins, the body finds it hard to shut it down, notes Robert B. Clark. The question has always been what triggers autoimmunity — the condition underlying multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease and a host of other disorders.
Clark’s team, at the University of Connecticut Health Center in Farmington, has stumbled onto one new candidate culprit. It’s a fatty compound — phosphoethanolamine dihydroceramide, or PEDHC for short — produced by bacteria residing in the human mouth. The researchers learned about it from a dental colleague, Frank Nichols, who noticed that it caused inflammation in test tube studies and showed up in human tissues that experienced inflammation.
Curious about whether it might affect autoimmunity, Clark’s group tested PEDHC in a mouse model for MS known as experimental autoimmune encephalomyelitis.