Is Periodontal Disease an Autoimmune Disorder?
By Elaine Moore
Evidence indicates that periodontal disease is an autoimmune disorder triggered by infectious organisms and an abnormal immune response to collagen.
Periodontal disease is an inflammatory condition affecting both the gums and the deep structures that house the roots of the teeth. Periodontal disease can cause the teeth to loosen and decay. Individuals with periodontal disease may experience bleeding of the gums when brushing, which is often the first sign of a problem.
The gums may also appear swollen and recede away from the teeth. Without early treatment the disease progress advances, affected gums separate from the tooth, causing a periodontal pocket to form. Ultimately, a large portion of the gum is destroyed, the bone surrounding the roots deteriorates and abscesses form, requiring extraction.
Researchers at the University of Maryland Medical Center published findings linking periodontal disease to autoimmunity in October 2010. This evidence of autoimmunity explains why regular flossing helps prevent periodontal problems, and it also explains why some people are affected by periodontal disease more than other people. This theory can also be linked to the fact that the risk of both periodontal disease and autoimmune disorders increase with age.
The Periodontal Immune Response
Normally, the mouth is inhabited by more than 350 different species of microorganisms. About five percent of these bacteria are gram-negative organisms, a type of bacteria normally found in the digestive tract. Evidence shows that a subset of gram-negative anaerobic bacteria is responsible for triggering the immune response that leads to plaque and tartar. Once formed, plaque and tartar go on to release toxins that stimulate the immune system to produce chemicals known as cytokines.
Cytokines are important for healing, but when pro-inflammatory cytokines are produced in excess, they cause inflammation and tissue damage. Several studies published in recent years suggest that cytokines related to these bacteria damage more than periodontal tissue. They may also have damaging effects on other organs throughout the body, including the heart. For this reason, one’s periodontal status offers clues to their cardiovascular health.
Destructive Bacteria and Viruses
Several anaerobic bacteria have been found to be responsible for triggering the autoimmune response in periodontal disease. These include:
Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. These two species of bacteria are reported to be particularly responsible for aggressive periodontal disease. Both P. gingivalis and A. actinomycetemcomitans, along with multiple deep pockets in the gum, are associated with resistance to standard treatments for gum disease. P. gingivalis in particular may double the risk for serious gum disease. P. gingivalis produces enzymes, such as one called arginine-specific cysteine proteinase, that may disrupt the immune system and lead to subsequent periodontal connective tissue destruction.
The organism Bacteroides forsythus is also strongly linked to periodontal disease.
Other bacteria associated with periodontal disease are Treponema denticola, T. socranskii, and P. intermedia. These bacteria, together with P. gingivalis, are frequently present at the same sites, and are associated with deep periodontal pockets.
Besides bacteria, several viruses have been implicated in the periodontal autoimmune response. These include herpes simplex and varicella-zoster virus, (the cause of chickenpox and shingles) and also cytomegalovirus and Epstein-Barr virus (EBV).
Researchers have previously found that individuals with chronic periodontal disease show evidence of antibodies to collagen, types I and III. The immune reaction to collagen appears to be more common in persons with other autoimmune disorders, particularly type I diabetes. Further research into the role that vitamin D insufficiency, which is common in autoimmune disease, plays in periodontal disease is warranted. ♦
© 5 Jan 2011 Copyrighted by Elaine Moore
Periodontal Disease. The University of Maryland Medical Center, October, 2010. accessed Dec 2, 2010. H.Z. Hirsch, A. Tarkowski, E.J. Miller, S. Gay, W. J. Koopman, J. Mestecky. Oral Pathology and Medicine. 2006. Autoimmunity to collagen in adult periodontal disease, 2006, April 28: 456-9.
Periodontal Disease. National Library of Medicine. April 2010. Accessed Jan 2, 2011.