"What’s the difference between an autoimmune disease like RA and periodontal disease" Periodontal disease is an infectious disease, and as with most infectious diseases, white blood cells of 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," Gaffen said.
IL-17 is a cytokine, a protein hormone made by "T helper" cells of the immune system that stimulate immunity. Gaffen noted that until recently, immunologists believed there were only two major types of "T helper" cells -- TH1 and TH2 -- which were believed to be responsible for nearly all immune system activities.
"This paradigm underwent a sea change in 2005 with the discovery of a new type of T cell that produces IL-17, now called TH-17," she said. "We know now that almost all autoimmune diseases, at least in the mouse model, are caused by TH-17 cells. This new information has forced scientists to revise completely how they view their favorite disease. Everyone now has to rethink the causative mechanism."
Gaffen said IL-17 likely would be toxic if given systemically, so it may not be a therapeutic candidate to increase immunity. But inhibitors of IL-17 are considered important targets for drugs to treat autoimmune diseases such as RA and psoriasis.
On the down side, however, this new finding indicates that inhibiting IL-17 too much could put people taking such a drug at risk for opportunistic infections such as periodontal disease and tuberculosis, she noted.
Source:University at Buffalo