Researching Asthma One Dust Particle at a Time

A day in the life: emerging from beneath the basement’s musty sofa after she picked apart the splinters of the rotting table leg, the child then wanders into the little-used and little-cleaned guest bathroom, playing with her imaginary friend in the cupboard beneath the leaky sink, before finally she scrambles across the dusty living room carpet and into the crawlspace in the garage, sneezing five whole times.

Now repeat this day 2,500 times.

This variety of environments is one reason researchers have a difficult time determining what causes a child like this to develop asthma—a disease that growing evidence suggests is associated with microbial exposure.

Previous researchers have tried to overcome these difficulties by searching for specific fungal species that increase the risk of asthma development. However, new research from associate professor of chemical and environmental engineering Jordan Peccia and environmental engineering doctoral student Karen Dannemiller suggests that asthma may not be caused by any one microbe.

Rather, working with the California Department of Public Health and faculty at the University of California, the team found that asthma development was associated with early life exposure to low fungal diversity. Moreover, no one microbe was associated with asthma development, and one fungal species identified by the researchers may possibly inhibit development of the disease. Perhaps asthma can therefore be prevented by early-life exposure to a large diversity of microbes, or at least to the the “right” microbes.

The study, recently published in Indoor Air, is significant for being the first to examine the relationship between asthma development and fungal diversity in house dust using DNA barcoding, a next-generation method of DNA sequencing that identifies members of a fungal community using short genetic markers. While culturing (the traditional fungal measurement technique) severely underestimates the quantity and diversity of microorganisms, the team’s pyrosequencing-based method provides accurate, quantitative identification down to the species level.

Data for the research was obtained from the Center for the Health Assessment of Mothers and Children of Salinas birth cohort, which collected house dust at age 12 months and determined asthma status at age 7 years. The dust samples were analyzed during lead author Dannemiller’s internship with the California Department of Public Health, an internship undertaken as part of the School of Engineering’s Advanced Graduate Leadership Program. “We had a unique opportunity to advance scientific understanding by combining cutting-edge measurement techniques from engineering with skilled epidemiological methods,” she says. “This was a great opportunity to get involved in interdisciplinary research.”