UKY DENTAL COBRE: ORAL INFECTIONS: COX-2

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Specific Aim 1. Determine the role of COX-2 in P. gingivalis-induced periodontal disease and atherosclerosis. Periodontitis is a chronic inflammatory disease resulting from microbial infection of the oral cavity. The disease is initiated by gram-negative anaerobic species including Porphyromonas gingivalis. P. gingivalis infection may produce inflammation localized within the oral cavity which results in alveolar bone resorption and may produce a systemic inflammatory response resulting from bacteremia. The systemic inflammatory response is thought to account for the increased risk of developing complications of cardiovascular disease in patients with periodontitis. Prostaglandins are a class of inflammatory mediators that are significantly increased in diseased periodontal tissues. The synthesis of prostaglandins requires the activity of a cyclooxygenase, and cyclooxygenase-2 (COX-2) is the isoform that is highly induced by gram-negative bacterial products and is increased in atherosclerotic lesions. The current studies utilized an established mouse model of P. gingivalis-induced periodontitis to examine the role of COX-2-derived prostaglandins in alveolar bone resorption and atherosclerosis. Alveolar bone resorption and cardiovascular disease resulting from P. gingivalis requires chronic infection to be established in the oral cavity of the mice. Therefore, the mice are inoculated with P. gingivalis 4 days a week, every 3rd week, over a 12 week course. We have optimized the PCR technique to confirm that chronic infection with P. gingivalis is established in the mice. We have also utilized the highly sensitive technique, real-time PCR, to examine the expression of COX-2, as well as downstream prostaglandin synthases in aortic tissue. Furthermore, we have optimized immunohistochemical analysis for detection of COX-2 protein expression in the aortas of mice. These procedures will allow us to examine the effects of P. gingivalis infection on the expression of COX-2 and downstream prostaglandin synthases. Studies are in progress to examine the effectiveness of genetic or pharmacological inactivation of COX-2 in reducing P. gingivalis-induced alveolar bone resorption and atherosclerosis in mice. Specific Aim 2. Define the role of 12/15-lipoxygenase in P. gingivalis-induced periodontal disease and atherosclerosis. Angiotensin II (AngII) markedly accelerates atherogenesis in hyperlipidemic mice. Moreover, AngII increases the expression of 12/15-lipoxygenase (12/15-LO). Deficiency of 12/15-LO markedly attenuates atherosclerosis in hyperlipidemic mice. Therefore, we sought to determine if 12/15-LO plays a role in AngII-induced vascular disease. Age matched male apolipoproteinE deficient (apoE-/-) mice or 12/15-LO deficient apoE-/- mice were infused with AngII (1,000 ng/kg/min) for 28 days. Total serum cholesterol or lipoprotein profile was not altered in 12/15-LO deficient mice following AngII infusion compared to control. 12/15-LO modestly decreased AngII-induced atherosclerotic lesion formation (12/15-LO+/+: 1.26% vs 12/15-LO-/-: 1.99%; P = 0.12) on the intimal surface of the aortic arch however, this decrease did not reach statistical significance. Additionally, 12/15-LO deficiency decreased the incidence of AngII-induced abdominal aortic aneurysm formation (12/15-LO+/+: 42% vs 12/15-LO-/-: 17%; P = 0.12) and the abdominal aortic diameter (12/15-LO+/+: 1.6 mm vs 12/15-LO-/-: 1.1 mm; P = 0.11), however, the reduction in both of these parameters did not reach statistical significance. While these results suggest 12/15-LO does not significantly alter AngII-induced atherosclerosis and AAA formation, the number of mice utilized in these studies did not result in a power of 0.08. This coupled with the trend toward a decrease in both atherosclerosis and AAA formation suggest that additional studies are required to define the effect of 12/15-LO on AngII-induced vascular disease.