A Breath of Fresh Air: An Interview With Dr. Chung-Wai Chow
By: Ekaterina An
Dr. Chung-Wai Chow, MD, PhD, FRCPC
Staff Physician, University Health Network
Scientist, Toronto General Research Institute
Assistant Professor, Dalla Lana School of Public Health, University of Toronto
Member, Institute of Medical Science
As a lung transplant physician, Dr. Chung-Wai Chow sees, first-hand, the harmful effects of air pollution on her patients. Her dual role as both a clinician and a scientist allows her to tackle this problem from both basic science and clinical research perspectives. Dr. Chow’s research is centered around the key theme of using clinical and animal models to understand the effects of environmental air pollution on respiratory health,. I recently had the chance to sit down with Dr. Chow to discuss her research.
Exposure to air pollution is linked to a number of lung diseases, including asthma, chronic obstructive pulmonary disease, and chronic organ rejection in lung transplant patients. However, the specific underlying biological mechanisms are still unclear. “A lot of underlying lung disease is due to the modulation of the immune system and its abnormal regulation. There is a lot of epidemiological data that links air pollution to poor health outcomes. Of course, pollution changes over time and geographical location. But when you look at the data on the whole, there is an underlying theme of inflammation. So one of the things I’m really interested in is trying to figure out what actually regulates this inflammatory response”, explains Dr. Chow.
Traditionally, experimental models of the effects of air pollution on respiratory health involve exposing model organisms or cell lines to specific pollutants from a certain geographical location, or direct emissions from car engines. However, as with all scientific models, these are not always an accurate reflection of the circumstances of exposure in real life. “One of the criticisms of experimental models is that researchers use very high concentrations of pollutants—they do not use realistic amounts. Further, animals and cells are exposed to only one or two pollutants at a time, even though we know that when humans are exposed to environmental pollutants, this is not the case,” says Dr. Chow. In order to address some of these shortcomings, Dr. Chow and her team partnered with Dr. Arthur Chan, a chemical engineer at the University of Toronto, to build a simulation system that allows mice to be exposed to different concentrations and combinations of pollutants that the researchers wish to examine. “We can actually titrate the type of pollutants to reflect pollutants found in Toronto, Mumbai, or Beijing, which is really exciting. This system is also great because one of the other challenges to doing this type of research is that experimental human exposures are difficult to do, and even with mouse exposures, most animal facilities will only allow you to take the mice out once. So another advantage of our system is that it is fairly small and portable—about the size of a mini-fridge—so we are able to do the experiments inside the animal facility. This allows us to have repeated exposures over time in a way that mimics typical human exposure situations,” says Dr. Chow. “This type of repeated-exposure system is one of only two in North America.”
However, Dr. Chow’s research extends beyond animal models. Dr. Chow says, “On the human, clinical side, I’m a lung transplant doctor. And recently, there has been a lot of evidence, from both our centre and a larger European study, which links exposure to air pollution to chronic lung rejection. Now, what is interesting about this is that the pollutants in Toronto differ from those in Europe. However, we are still seeing the same inflammatory response. The lung is the only organ, with the exception of skin, that is continuously exposed to the environment. So there must be something in the pollutants that is triggering this ongoing inflammatory response.” To that end, Dr. Chow is currently conducting a Canadian Institutes for Health Research (CIHR)-funded study that aims to examine the effects of traffic-related air pollutants on lung transplant patients using personal pollution monitoring. “We go into the homes of newly transplanted patients and leave a whole bunch of air pollution monitors in place. We coordinate this monitoring period with dates when the patients are regularly giving samples—blood, urine, and lung lavage fluid—as part of their routine post-transplant care. This allows us to obtain samples without having to inconvenience the patients. The idea is that, at the end of all this, we will look at specific pollutants that are actually taken up in the body, and correlate them to those identified from the personal pollution monitors. The hypothesis is that whatever you absorb is what causes problems,” says Dr. Chow. The personal pollution monitoring that is carried out is impressively thorough, given the difficulties of measuring all of the pollutants that individuals may be exposed to on a daily basis. The home monitoring system consists of a small, rolling suitcase that is outfitted with several monitors to collect particulate matter of different sizes, as well as semi-volatile organic carbons which are often found in car emissions and household products. Participants are also provided with a personal pollution monitoring device that they carry with them, although this is often challenging as they are recovering from their transplant surgery, acknowledges Dr. Chow.
When asked about the future directions of her research, Dr. Chow states that she hopes to integrate both her basic science and clinical research findings. “We’re hoping that with the collection of the biological samples from patients and from the experimental animals, we will be able to develop a biosignature of different inflammatory biomarkers of people who are at increased risk of inflammation. [Then], you can screen for that signature to identify those who are at risk and think about mitigation strategies. For example, making sure homes are well vacuumed and that there is good air exchange. These are also the people whom you might want to treat earlier, if there is any clinical sign of decline in lung function or immunologic response. This could be helpful in transplant medicine in particular as abnormal findings do not always warrant treatment,” explains Dr. Chow. Taking her research a step further, Dr. Chow says, “I hope that these findings will impact not only lung transplant patients, but the population as a whole, because we can go back to the pollutants in our studies and identify the source of these emissions. And then [we can] ask: can we bring in regulation to limit these emissions?”
More recently, Drs. Chow and Chan were awarded a second CIHR grant to specifically assess the long-term effects of air pollutants resulting from the Alberta wildfire. The unique ongoing collaborations of these two University of Toronto researchers will allow them to evaluate the physico-chemical properties of the wildfire pollutants (Dr. Chan) and correlate biological responses to these pollutants in studies using cell and animal models (Dr. Chow).
Given the clear link between environmental air pollution and lung disease, Dr. Chow’s research could go a long way towards improving care for lung transplant patients. With the launch of the Alberta wildfires project in the summer of 2017, her findings are expected to be applied to other vulnerable populations, as well as inform policy-makers and improve public health regulations around the emission of harmful particulate matter. The balance of basic science and clinical research that Dr. Chow has achieved in her work can help us all breathe a little easier.