Periodontitis in humans and non-human primates: oral-systemic linkage inducing acute phase proteins

The acute phase response (APR) represents a systemic counterpart to the localized inflammatory response. This report describes patient-oriented and non-human primate model studies to determine the effect of periodontal disease on systemic acute phase proteins (APP).

Patient-oriented studies included comparison of the levels of APP, using enzyme-linked immunosorbent assay (ELISA), with the presence and severity of periodontitis in localized chronic periodontitis (LCP), generalized aggressive periodontitis (GAP), and Sjogren's syndrome (SS) patients. The non-human primate experiments evaluated the serum level of APPs under natural conditions, following mechanical hygiene, experimental gingivitis, and during ligature-induced periodontitis.

Analysis of the LCP population showed what appeared to be a threshold of periodontal disease severity required for elevating the C-reactive protein (CRP) and haptoglobin (HG). The results demonstrated a significant elevation in CRP in the GAP versus the control groups, as well as lower levels of all mediators in healthy non-smokers (HNS) versus smokers (HS), suggesting that these systemic inflammatory markers were altered in response to challenge by noxious materials from smoking. Significantly different levels of CRP, HG, and alpha1-antiproteinase were noted in the SS patients suggesting that the autoimmune aspects of Sjögren's syndrome may impact upon oral health and systemic responses. Parallel evidence was also obtained from the primate studies. Providing mechanical oral hygiene, which significantly lowered clinical inflammation and bleeding of the gingiva, decreased the serum APP levels. Both CRP and fibrinogen were significantly elevated during progressing periodontitis, which also appeared to have an impact on serum lipids and lipoproteins.

These findings supported results relating chronic oral infections and the inflammation of periodontitis as contributors to and/or triggers for systemic inflammatory responses. Finally, similarities in the clinical and microbiological parameters of gingival inflammation and periodontitis between humans and non-human primates was extended to identification of changes in serum APP in the non-human primates that appeared to be in direct response to the induction of progressing periodontitis. These systemic changes provide additional evidence for the biological plausibility of periodontal infections contributing to various systemic diseases.