Researchers from the University of Buffalo found that a component called IL-17 helps protect bones in the oral cavity. Conversely, the same component had been found in separate research to be a key cause of bone destruction and inflammation in people with rheumatoid arthritis (RA) and other autoimmune diseases. Autoimmune diseases are caused when the immune system attacks healthy body tissue and organs.

Studies in rats and mice have suggested that blocking or reducing IL-17 may be an effective therapy for people with RA, as well as other autoimmune conditions such as multiple sclerosis, colitis, psoriasis and lupus. The researchers conducted studies on mice that were bred to have no IL-17 receptors (and thus unable to use IL-17). They found that these mice were more likely to experience bone loss from gum (periodontal) disease, instead of receiving the protective effects in that area as was seen for the autoimmune diseases. Gum disease is infection or inflammation of the gums, tissues and bones surrounding and supporting the teeth.

"What's the difference between an autoimmune disease like RA and periodontal disease?" Sarah L. Gaffen, the study's senior author, asked said in a press release. "Periodontal disease is an infectious disease, and as with most infectious diseases, white blood cells in the innate immune system called neutrophils play a critical role in fighting infections. In fact, humans with neutrophil defects usually lose all their teeth by the time they are 20 due to severe periodontal disease. It turns out that IL-17 is really important in regulating neutrophils by causing other cells in the vicinity to recruit these infection fighters to the infection site."

However, the Buffalo researchers noted that more studies are needed to evaluate all of the potential outcomes of reducing IL-17. Despite the protective effects of IL-17 on the oral cavity bones, it may be unsuitable to treat bone loss because large amounts of the protein can be toxic to the system.

Results of the study were published in the May issue of Blood. The study was funded in part by grants from the National Institutes Health.

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