HEALTH NEWS

Study Title:

The Link Between Oral Hygiene and Heart Disease

Study Abstract

From press releases:

Bleeding gums linked to heart disease

Bad teeth, bleeding gums and poor dental hygiene can end up causing heart disease, scientists heard today (Thursday 11 September 2008) at the Society for General Microbiology's Autumn meeting being held this week at Trinity College, Dublin.

People with poor dental hygiene and those who don't brush their teeth regularly end up with bleeding gums, which provide an entry to the bloodstream for up to 700 different types of bacteria found in our mouths. This increases the risk of having a heart attack, according to microbiologists from the University of Bristol and the Royal College of Surgeons in Ireland.

"The mouth is probably the dirtiest place in the human body," said Dr Steve Kerrigan from the Royal College of Surgeons in Dublin, Ireland. "If you have an open blood vessel from bleeding gums, bacteria will gain entry to your bloodstream. When bacteria get into the bloodstream they encounter tiny fragments called platelets that clot blood when you get a cut. By sticking to the platelets bacteria cause them to clot inside the blood vessel, partially blocking it. This prevents the blood flow back to the heart and we run the risk of suffering a heart attack."

The only treatment for this type of disease is aggressive antibiotic therapy, but with the increasing problem of multiple drug resistant bacteria, this option is becoming short lived.
"Cardiovascular disease is currently the biggest killer in the western world. Oral bacteria such as Streptococcus gordonii and Streptococcus sanguinis are common infecting agents, and we now recognise that bacterial infections are an independent risk factor for heart diseases," said Professor Howard Jenkinson from the University of Bristol. "In other words it doesn't matter how fit, slim or healthy you are, you're adding to your chances of getting heart disease by having bad teeth."

Researchers at Bristol have been investigating the ways in which the bacteria interact with platelets in order to develop new and improved therapies.

"Most of the studies that have looked at how bacteria interact with platelets were carried out under conditions that do not resemble those in the human circulatory system. We mimicked the pressure inside the blood vessels and in the heart", said Professor Jenkinson. "Using this technique we demonstrated that bacteria use different mechanisms to cause platelets to clump together, allowing them to completely encase the bacteria. This shields the bacteria from the cells of our immune systems, which would normally kill bacteria, and most importantly also protects them from antibiotics."

These findings suggest why antibiotics do not always work in the treatment of infectious heart disease and also highlight the need to develop new drugs to treat this disease. "We are currently in the process of identifying the exact site at which the bacteria stick to the platelets," said Professor Jenkinson. "Once this is identified we will design a new drug to prevent this interaction."
"We also identified several proteins on the bacteria that lead to platelet clumping," said Dr Kerrigan. "Genetic deletion of these proteins from the bacteria prevented the platelets from clumping which shows that these proteins play an essential role and may be candidate proteins for new drug development or producing vaccines."

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Brush Your Teeth To Reduce The Risk Of Heart Disease

Heart disease is the leading cause of death worldwide. However, many people with cardiovascular disease have none of the common risk factors such as smoking, obesity and high cholesterol. Now, researchers have discovered a new link between gum disease and heart disease that may help find ways to save lives, scientists heard September 9, 2008 at the Society for General Microbiology's Autumn meeting being held at Trinity College, Dublin.

In recent years chronic infections have been associated with a disease that causes "furring" of the arteries, called atherosclerosis, which is the main cause of heart attacks. Gum disease is one of the most common infections of humans and there are now over 50 studies linking gum disease with heart disease and stroke.

"A number of theories have been put forward to explain the link between oral infection and heart disease," said Professor Greg Seymour from the University of Otago Dunedin, New Zealand. "One of these is that certain proteins from bacteria initiate atherosclerosis and help it progress. We wanted to see if this is the case, so we looked at the role of heat shock proteins."
Heat shock proteins are produced by bacteria as well as animals and plants. They are produced after cells are exposed to different kinds of stress conditions, such as inflammation, toxins, starvation and oxygen and water deprivation. Because of this, heat shock proteins are also referred to as stress proteins. They can work as chaperone molecules, stabilising other proteins, helping to fold them and transport them across cell membranes. Some also bind to foreign antigens and present them to immune cells.

Because heat shock proteins are produced by humans as well as bacteria, the immune system may not be able to differentiate between those from the body and those from invading pathogens. This can lead the immune system to launch an attack on its own proteins. "When this happens, white blood cells can build up in the tissues of the arteries, causing atherosclerosis," said Professor Seymour.

"We found white blood cells called T cells in the lesions of arteries in patients affected by atherosclerosis. These T cells were able to bind to host heat shock proteins as well as those from bacteria that cause gum disease. This suggests that the similarity between the proteins could be the link between oral infection and atherosclerosis," said Professor Seymour.
This molecular mimicry means that when the immune system reacts to oral infection, it also attacks host proteins, causing arterial disease. These findings could fundamentally change health policy, highlighting the importance of adult oral health to overall health and wellbeing: control of gum disease should be essential in reducing the risk of heart disease.

"This is a significant step towards a more complete understanding of heart disease and improving treatment and preventive therapies," said Professor Seymour. "An understanding of all the possible risk factors could help lower the risk of developing heart disease and lead to a significant change in disease burden."

Study Information

Brush Your Teeth To Reduce The Risk Of Heart Disease.
Society for General Microbiology's Autumn meeting being held at Trinity College, Dublin.
2008 September