By Dr. Catalina Lopez-Correa
The number of people, particularly children, suffering from asthma has grown significantly over the past few decades. Today, asthma is one of the most common chronic diseases affecting one in seven Canadian children. And while doctors don’t entirely understand why some develop this serious disease, and others don’t, researchers have determined that it could be a mix of your genetics, environment or other factors.
Asthma affects the airways that carry air in and out of your body. With asthma, your airways get inflamed and swell up, causing the muscles around them to tighten, making it hard to get air in and out. At the same time, your airways might also make more mucus than normal, blocking your airway and making it difficult to breathe. Inflammation can be triggered by common substances in the environment such as pollen, pet dander, mold, or cigarette smoke. When you have asthma, your body perceives these substances as threats and overreacts in response, causing inflammation in your airways to the point of malfunction.
Dr. Stuart Turvey, one of the co-leaders of the Canadian Healthy Infant Longitudinal Development (CHILD) study, is following 3,500 Canadian children in the hopes of identifying the root causes of asthma. Turvey, a pediatrician who specializes in allergy and immunology at BC Children’s Hospital Research Institute, is working with Drs. Michael Kobor and Brett Finlay of the University of British Columbia and Dr. Padmaja Subbarao of The Hospital for Sick Children in Ontario to determine which infants in the CHILD study are most likely to develop asthma by looking at microbes in their stool samples. Turvey and his team believe evidence for the cause of asthma points to something either in (or missing from) the environment that children are growing up in.
“When I went to medical school, I was taught to name bacteria and to kill them with antibiotics,” recalls Turvey, “But the reality is that in the vast universe of bacteria, only a handful of them make us sick, while the majority actually help make us healthy.”
Children who are exposed to bacteria and viruses early in life are in a lower risk group for developing asthma. Alternatively, children who lack exposure are at a higher risk. This may include children born through Caesarian section, missing exposure to their mother’s vaginal birth canal, or babies who are given antibiotics, which wipe out bacteria in the gut, although these initial observations will need to be scientifically confirmed.
As part of the CHILD study, stool samples were collected from children at birth, three months of age and one year. When some of these children began to develop asthma as they grew, researchers were prompted to examine the early stool samples (frozen in the lab) to see if there was something different in their microbial community (Microbiome). What they found (or more accurately, didn’t find) may have opened the door to preventing asthma. The team was able to discover the absence of four bacteria: Faecalibacterium, Lachnospira, Veillonella and Rothia (FLVR).
The absence of these four FLVR bacteria, which can be detected at as early as three months of age, suggests you may be in a higher risk group for developing asthma. Armed with this knowledge, the door may be opened to find ways to intervene, with the goal of preventing asthma from developing in the first place.
Through funding by Genome British Columbia, Genome Canada, the Canadian Institutes of Health Research (CIHR), and other partners, Turvey and his team are using genetic sequencing to confirm their previous findings and to examine the entire microbiome to determine once and for all if these missing microbes are leading to asthma, and if so, look at developing ways to replace these missing microbes. A cure may still be a long way off, but the team is cautiously optimistic about the possibilities of using the microbiome to prevent or potentially treat asthma.
Dr. Catalina Lopez-Correa is Chief Scientific Officer and Vice President, Sectors at Genome British Columbia.