Systemic inflammation in cardiovascular and periodontal disease: comparative study

Abstract

Epidemiological studies have implicated periodontal disease (PD) as a risk factor for the development of cardiovascular disease (CVD). These studies addressed the premise that local infection may perturb the levels of systemic inflammatory mediators, thereby promoting mechanisms of atherosclerosis. Levels of inflammatory mediators in the sera of subjects with only PD, only CVD, both diseases, or neither condition were compared. Subjects were assessed for levels of C-reactive protein (CRP), serum amyloid A (SAA), ceruloplasmin, alpha(1)-acid-glycoprotein (AAG), alpha(1)-antichymotrypsin (ACT), and the soluble cellular adhesion molecules sICAM-1 and sVCAM by enzyme-linked immunoabsorbent and/or radial immunodiffusion assays. CRP levels in subjects with either condition alone were elevated twofold above subjects with neither disease, whereas a threefold increase was noted in subjects with both diseases (P = 0.0389). Statistically significant increases in SAA and ACT were noted in subjects with both conditions compared to those with one or neither condition (P = 0.0162 and 0.0408, respectively). Ceruloplasmin levels were increased in subjects with only CVD (P = 0.0001). Increases in sVCAM levels were noted in all subjects with CVD (P = 0.0054). No differences in sICAM levels were noted among subject groups. A trend toward higher levels of AAG was noted in subjects with both conditions and for ACT in subjects with only PD. Immunohistochemical examination of endarterectomy specimens of carotid arteries from subjects with atherosclerosis documented SAA and CRP deposition in association with atheromatous lesions. The data support the hypothesis that localized persistent infection may influence systemic levels of inflammatory mediators. Changes in inflammatory mediator levels potentially impact inflammation-associated atherosclerotic processes.

FIG. 1.

Percentage of subjects with elevated APP and soluble CAM. Solid bars represent PD⁻ CVD⁻ subjects, horizontal lines represent PD⁺ CVD⁻ subjects, open bars represent PD⁻ CVD⁺ subjects, and diagonal lines represent PD⁺ CVD⁺ subjects. Normal levels as reported by the kit manufacturers were as follows: CRP range, 0.6 to 1.9 μg/ml; SAA range, 1.0 to 10.0 μg/ml (reported mean, 3.0 to 4.0 μg/ml); AAG range, 512 to 869 mg/liter (mean, 683 mg/liter); ACT range, 356 to 596 mg/liter (mean, 476 mg/liter); ceruloplasmin range, 230 to 370 mg/liter (mean, 292 mg/liter); sVCAM range, 395 to 714 ng/ml (mean, 553 ng/ml); and sICAM range, 114.7 to 306.4 ng/ml (mean, 210.6 ng/ml).

FIG. 2.

Confocal images of immunofluorescence microscopy studies carried out on 4-μm-thick cross-sections of a carotid artery from a subject with atherosclerosis made with a cryocut microtome. The images document the deposition of APP along the vessel walls of carotid arteries obtained from patients who underwent endarterectomies. The vessels tested positive for the presence of DNA from periodontal pathogens (24). (A) Negative control. The vessel was incubated sequentially with normal rabbit serum and FITC-labeled anti-chicken IgG. Similarly, the vessels incubated sequentially with normal rabbit serum and FITC-labeled anti-rabbit IgG or incubations with secondary antibodies alone did not exhibit staining (data not shown). (B) CRP. The vessel was incubated sequentially with antibodies to CRP raised in chickens and fluorochrome-labeled anti-chicken IgG antibodies. (C) SAA. The vessel was incubated sequentially with antibodies to SAA raised in rabbits and fluorochrome-labeled anti-rabbit IgG antibodies. Deposition of SAA and CRP was observed along the intimal wall of the vessels. The extent of deposition varied among patients and was proportional to the severity of the atheromatous lesion formed along the vessel wall. The photomicrographs were obtained by using a Nikon epifluorescence microscope and the Bio-Rad MRC-024 three-channel laser scanning confocal imaging system equipped with a krypton argon laser operating at 514 nm at 100% power. The images were stored at 47 × 47 pixels (512 × 512 μ, full field) with a pixel size of 0.093 μ (final magnification, ×340).