AllerGen researchers find potential biomarker for occupational asthma

AllerGen investigators Drs Chris Carlsten and Scott Tebbutt may have found a blood biomarker that can be used to diagnose an occupational asthma associated with the BC forestry industry.

For a decade, Dr. Carlsten and his team have been diagnosing western red cedar asthma at the Vancouver General Hospital. The conventional diagnostic test takes two to three days to complete and requires that the patient inhale plicatic acid, a costly procedure that can be uncomfortable for the patient.

Plicatic acid naturally occurs in western red cedar trees and is released into the surrounding environment when the wood is cut or milled. Exposure to the acid has led to asthma in approximately 5% of the workers who regularly inhale it.

As part of the testing procedure, Dr. Carlsten routinely collects blood samples from the patients.

When Dr. Carlsten told Dr. Tebbutt—a biomarker expert always on the lookout for groups of people with a shared allergic response to an environmental trigger— about his collection of forestry workers’ blood, Dr. Tebbutt and his graduate student, AllerGen trainee Yolanda Yang, proposed a joint project that would use the samples to find a blood-based biomarker for western red cedar asthma.

“[The] idea was to use blood as a surrogate for what is going on in the lungs,” Dr. Carlsten explained in a University of British Columbia (UBC) press release.

A biomarker would make diagnosis much simpler, and could facilitate identifying the disease at an earlier stage, allowing workers to take preventative measures by limiting exposure, wearing safety equipment, or changing occupations.

Dr. Tebbutt focused his search on patterns unique to the RNA of white blood cells from patients who tested positive during the plicatic acid inhalation test.

He found higher levels of specific RNA molecules in the blood of six of seven patients whom Dr. Carlsten had diagnosed with occupational asthma. These molecules are produced by two genes and, in turn, produce proteins known to affect inflammation and stress responses.

According to the UBC press release, this biomarker discovery will constitute a breakthrough for the diagnosis of occupational asthma, once validated by further testing with a larger sample size. It could also lead to the identification of asthma triggers in other occupations.