Abstract TP198: Periodontitis Enhances Cerebral Microhemorrhage Development In A Mouse Model Of Hypertension

Introduction: Periodontitis is a highly prevalent disorder that is increasingly recognized as a risk factor for cerebrovascular disease. In this study we examined the role of periodontitis in the development of cerebral microvascular disease. Methods: Hypertension was induced in aged (17 months old) male C57BL/6J mice via infusion of angiotensin II (ATII) at 1000 ng/kg/min via Alzet pump over 4 weeks. Periodontitis was induced by giving P. gingivalis -LPS (20 μg in 2 μL) injections between the first and second maxillary molars on both the right and left sides twice a week for six weeks. At end of six weeks, we collected mouse brains (N=5 each for Hypertension, Periodontitis, Hypertension + Periodontitis, and Control) and performed standard histology using Prussian blue staining to detect cerebral microhemorrhages (CMH) formation at 20x magnification. The average number, total area, and size of Prussian blue-positive deposits were quantified. Results: ATII-induced hypertension in animals (Systolic blood pressure: 113±2 mmHg to 156±3 mmHg, mean+SE, p<0.0001; Diastolic blood pressure: 82±2 mmHg to 119±3 mmHg, p<0.0001). Presence of hypertension produced significant increase in number of CMH compared to controls (1.97±0.29 per cm 2 vs. 1.24±0.20 per cm 2 , p<0.05). Presence of periodontitis did not alter the number of microhemorrhages (1.68±0.13 per cm 2 vs.1.97±0.29 per cm 2 ). However, size of microhemorrhages doubled in the presence of periodontitis with hypertension (10.58±2.55 μm 2 per cm 2 vs. 5.05±1.15 μm 2 per cm 2 , p<0.05). Conclusions: In this mouse model of ATII-induced hypertension, periodontitis appears to increase size of CMH rather than induce development of new lesions. These findings suggest a role for periodontitis in cerebrovascular disease by modifying and exacerbating pre-existing stroke risk factors rather than acting as an independent risk factor.