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21-03-2013 | Oral medicine | Article

Antimicrobial proteins elevated in periodontitis


Free abstract

medwireNews: Levels of two antimicrobial proteins are raised in people with periodontal disease and may serve as markers for the condition, Turkish researchers believe.

"Beta-2 microglobulin (B2M) and alpha-2 macroglobulin (A2M) are assumed to be user-friendly and cost-effective markers for [asymptomatic] periodontal disease," write Abdullah Ertugrul (Yuzuncu Yil University, Van) and coauthors in the Australian Dental Journal.

B2M is a component of major histocompatibility type I molecules found on the surface of almost all adult cells and is known to be associated with tissue destruction in periodontitis. A2M is a major plasma protease inhibitor that is important for the inhibition and removal of proteolytically harmful endoproteases.

In this study, Ertugrul and team measured levels of B2M and A2M in gingival crevicular fluid from 80 patients. Twenty were periodontally healthy while 60 had varying degrees of gingival and periodontal disease.

Analysis revealed that mean A2M levels were highest in the group of patients with generalized aggressive periodontitis, lowest in periodontally healthy patients, and intermediate in patients with gingivitis and those with chronic periodontitis, at 452.1, 153.6, 199.5, and 382.2 ng/sample, respectively.

The same pattern was seen with mean B2M levels, at 109.2, 32.4, 58.3, and 87.3 ng/sample in patients with generalized aggressive periodontitis, no periodontal disease, gingivitis, and chronic periodontitis, respectively.

Further analysis identified positive correlations between clinical parameters - such as plaque index, gingival index, probing depth, clinical attachment loss, and bleeding on probing - and levels of both A2M and B2M, as well as with the volume of gingival crevicular fluid.

Ertugrul and colleagues suggest that A2M levels are elevated in periodontal disease because of the formation of pathologic pockets, which cause worsening inflammation and tissue damage.

"The positive correlation between A2M levels in gingival crevicular fluid and the increase in pocket depth clarifies the inflammatory origin of A2M elevation," they remark.

Similarly, B2M is released from lymphocytes so raised levels of the protein are presumably related to inflammatory processes, which are a key component of periodontal disease.

The researchers surmise that B2M and A2M "play key roles in the balance between periodontal health and disease." Furthermore they hypothesize that "tissues release B2Mand A2M to stop inflammation and inhibit the proliferation of microorganisms and this may be the reason for the high levels of B2M and A2M in the generalized aggressive periodontitis and chronic periodontitis groups."

They conclude: "A2M and B2M levels may not play a significant role in the pathogenesis of periodontal diseases, but further studies with a larger sample size are required to investigate this relationship further."

By Joanna Lyford, Senior medwireNews Reporter