Research Profile - The cold truth
Dr. Richard Leigh
A Calgary researcher has linked the development of asthma with frequent cases of the common cold
Sometime this year, Dr. Richard Leigh of the University of Calgary hopes to recruit a few good men – and women – to stick out their noses in the service of science.
"What we'll do is give people an experimental rhinovirus infection which we would put in their nose that would pretty much guarantee they'd get a common cold within the next 24 hours," says Dr. Leigh.
At a Glance
Who – Dr. Richard Leigh, GlaxoSmithKline-CIHR Professor in Inflammatory Lung Disease at the University of Calgary
Issue – Studies by Dr. Leigh and others have linked the rhinovirus – the bug behind the common cold – to the onset of asthma. While lifestyle changes can protect people with asthma from exposure to antigens like dust and cigarette smoke, staying clear of colds is nearly impossible.
Approach – Dr. Leigh and his colleagues are studying the impact of the rhinovirus on the cells and molecules in the lungs to see how the response to infection affects asthma.
Impact – This approach could lead to new therapies to prevent the cold virus from creating the pre-conditions for asthma or triggering attacks in people who already have it.
This sniffle challenge will help Dr. Leigh and his colleagues advance the important work they have already done linking the rhinovirus to the development of asthma. His previous studies have shown that individuals who get frequent colds develop scarring in their bronchial tubes – a condition with the oddly upbeat label of "airway remodeling."
This scarring is a characteristic of asthma, and is thought to be an important factor in causing airways to constrict too much and too quickly in response to allergens such as cat dander, dust mites or irritants such as cigarette smoke and cold air. Airway remodeling often occurs in early childhood, sometimes even before the clinical diagnosis of asthma has been established.
"Scarring is natural and part of any wound repair process," says Dr. Leigh, whose work is funded by the Canadian Institutes of Health Research (CIHR). However "an over-exuberant wound response to the rhinovirus," appears to predispose the development of persistent asthma, he says. "This over-exuberance leads to remodeling and causes structural change and a narrowing of the airways."
A GlaxoSmithKline-CIHR Professor in Inflammatory Lung Disease, Dr. Leigh wants to understand how the lungs react to rhinovirus infections in order to gain insights into how these infections may result in the development of asthma.
"Then we could start looking at therapeutic interventions," he says. "There could be two approaches: strengthen the host response to limit the impact of the viral infection on the airways; or, dampen down that response so you don't get that over-exuberant scarring response."
Dr. Leigh is currently applying to Health Canada for approval to conduct the get-a-cold test, but there is already industry interest in his innovative approach to battling asthma – a condition that affects one in about every dozen Canadians age 12 and over.
While people with asthma are routinely encouraged to make lifestyle changes to prevent attacks – by avoiding dogs and cats, second-hand tobacco smoke, pollens, dust and other antigen sources – keeping clear of the common cold virus isn't really an option.
"We can't go around saying, 'Live in a bubble.' But perhaps we can develop an intervention so that we can block the virus from getting into the cell and into your lungs and airways."
Hence the need for 15-18 people – some with asthma or a predisposition for it, some without – to volunteer to catch a cold. Dr. Leigh doesn't see a problem rounding up recruits. "People are always interested in contributing to the advancement of biomedical science. Besides, the kind of cold we're talking about is a fairly mild one."
"The rhinovirus itself is a fairly tame one. It doesn't cause a lot of cell destruction in the airways, unlike say the influenza virus. But your body mounts a very exuberant response to the rhinovirus that causes exacerbations of asthma and also likely leads to airway remodeling."
-- Dr. Richard Leigh