Already around 50 studies link 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.
In recent years chronic infections have been associated with a disease that causes "furring" of the arteries, called atherosclerosis. Seymour: "One of the theories 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.
MEDICA.de; Source: Society for General Microbiology