Good oral hygiene may help recovery after acute cardiovascular events such as heart attacks and aortic dissection, according to research presented today at Frontiers in CardioVascular Biology (FCVB) 2018, a European Society of Cardiology congress. The study in mice found that the bacteria that cause gum disease (periodontitis) also impair the healing of blood vessels.
Research on the prevention of cardiovascular disease, which remains the top killer worldwide despite improved treatments, has focused on conventional risk factors including hypertension, diabetes, and high cholesterol. The importance of oral health, which is often poor in people with other cardiovascular risk factors, has been neglected.
There is increasing evidence that gum disease increases the risk of cardiovascular disease and leads to worse outcomes in patients with atherosclerosis (clogged arteries).
Dr. Sandrine Delbosc, author of the current study and associate investigator, Inserm Laboratory for Vascular Translational Science, Paris, France, said: "Our previous research in rats found periodontal bacteria in severely atherosclerotic arteries, suggesting that these bacteria may be the link between gum disease and cardiovascular disease."
The researchers hypothesised that periodontal bacteria enter the bloodstream through bleeding gums, a common symptom of gum disease. The bacteria then adhere to atherosclerotic lesions, which contain bacterial "food" such as protein, and impede healing of the lesions.
This hypothesis was tested in the current study using a mouse model of atherosclerosis complicated by aortic aneurysm. To mimic the repeated entry of periodontal bacteria into the blood that occurs in gum disease, the researchers injected Porphyromonas gingivalis, the main periodontal bacterium, into the bloodstream once a week for four weeks. A control group of mice was injected with saline solution.
The researchers found that a significantly higher proportion of the mice injected with bacteria died (23 out of 34; 68 percent) compared to the control mice (eight out of 23; 35 percent) (p<0.05). Death was caused by impaired aortic healing and a resulting rupture of the aorta. Mice injected with bacteria had Porphyromonas gingivalis at the site of aortic rupture.
A subsequent analysis in mouse cells showed that gingipaïn, an enzyme produced by Porphyromonas gingivalis, inhibits the repair function of immune cells.
Dr. Delbosc said: "Our study shows that the bacteria that cause gum disease impair the healing and repair of arteries. This impaired healing may be due to an enzyme produced by the bacteria that stops the body's immune cells from repairing the arteries."
She continued: "Periodontitis can be prevented with flossing and brushing. Our study suggests that good oral health could significantly improve the outcome of patients who have an acute cardiovascular event."
Dr. Delbosc noted that the findings of the study need to be confirmed in patients. Her research group is designing a study to examine whether using non-surgical (scaling, root planing) and if necessary surgical periodontal treatments to stop the entry of periodontal bacteria into the bloodstream of patients with cardiovascular disease improves outcomes.
She concluded: "We hope that our experimental and clinical studies will promote the development of new recommendations for oral health care in patients with cardiovascular diseases."
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