With Great Power Comes Great Responsibility: The Spiderman Bacteria
Lyme disease is carried by ticks, but according to new research by a team in the Department of Laboratory Medicine and Pathobiology (LMP), the bacteria responsible for it behaves more like an evil Spiderman.
After a bite from an infected tick, a bacterium called Borrelia burgdorferi travels through the blood stream. The bacteria then attach to the inner surfaces of blood vessels before travelling into the surrounding tissue and causing symptoms. To do this, the researchers found that the bacterium exploits one of the most common blood proteins, called plasma fibronectin.
“This common protein normally circulates in the blood in high concentrations and it isn’t usually sticky,” Tara Moriarty, aprofessor in the Faculty of Dentistry cross-appointed to the Faculty of Medicine's Department of Laboratory Medicine and Pathobiology. “But when the Lyme disease bacteria are present, they coat themselves with this protein, which becomes sticky and forms a web at one end of the bacterium. That web helps the bacteria adhere more strongly to the blood vessels.”
Then, like Spiderman shooting webs and using them to swing from building to building, the bacteria invade the body, clinging to the insides of blood vessels and causing illness.
Lyme disease is one of the fastest-growing infectious diseases on this continent. Left untreated, it can cause serious problems like recurring arthritis attacks and neurological problems.
In Canada alone, there was a nearly five-fold jump in the number of reported cases— from 143 to more than 700 — between 2010 and 2015. It’s believed the true number may actually be much higher since mild cases often clear on their own and may not be reported.
The U.S. Centres for Disease Control and Prevention (CDC) has until recently reported an average of 30,000 cases of the disease. However, new research suggests there could be anywhere between 300,000 and one million cases per year.
A number of studies have suggested that global warming will increase the geographic range of disease-carrying ticks, putting increasing numbers of Canadians at risk of contracting the disease.
“When I began working on my PhD six years ago, most people had no idea what I was talking about when I said I was studying Lyme disease,” says the study’s lead author, PhD student Alexandra Niddam. “Because the disease is becoming more prevalent, people are becoming more aware of it. This is an up and coming field and I’ve watched it evolve throughout my degree.”
Moriarty and Niddam say their discovery could one day help researchers develop new treatments to help people with Lyme disease.
“Perhaps we’ll be able to target the specific receptors that mediate the interactions between Borrelia and people’s blood vessels. This could help us stop the bacteria from spreading in the bloodstream and hopefully prevent people from developing symptoms in the future,” says Niddam.
The discovery also opens doors for researchers looking at other diseases like Methicillin-resistant Staphylococcus aureus (more commonly known as MRSA) and Streptococcus pyogenes, which are responsible for rheumatic fever and many serious blood stream infections.
“Because we know many bacteria can bind plasma fibronectin, there’s a possibility others might spread in the bloodstream like Borrelia,” says Moriarty. “So instead of targeting the specific proteins in each bacterium that do this, it might actually be easier to develop something that targets interactions mediated by fibronectin if it is like a universal adapter.”
The study was published on April 10th, 2017 in the journal Proceedings of the National Academy of Sciences.