By Ariel Root

In his chemistry departmental office at 杏吧原创 University, Prof. J David Miller tries to identify where it all started. Before he participated in or chaired expert panels of the WHO, the US FDA, AIHA, AAAAI, or the World Bank; before he partnered with Health Canada and Environment Canada to establish health policy; and much before he became a Professor and NSERC Research Chair at 杏吧原创 in 2000. Miller identifies three elements that founded his interests in fungal metabolites, starting with an early introduction to fungal metabolites in what his father鈥檚 job (chemist and brew-master at Moosehead Breweries in Saint John). Miller attributes the other two elements to exceptional organic chemistry training, and introduction to inspiring mycologist Norman Whitley while pursuing his undergraduate at the University of New Brunswick.

Miller鈥檚 interests in fungal metabolites further intensified during his graduate studies, as he examined interference competition; 鈥渨hy some fungi don鈥檛 get along; why some appear and some don鈥檛, or why some result in animal morbidity.鈥� Subsequently, while completing his postdoctoral work, Miller was offered a job at Agriculture Canada where he led the Fusarium mycotoxin program, examining toxins growing in the Canadian grain systems鈥斺�渁nd that really matters,鈥� Miller emphasizes. Mycotoxin contamination of crops has a very large economic consequence to the agri-food systems, and particularly in developing countries has very important public health implications.

He says, you need passion.

Miller chaired a working group of world-leading experts convened by the聽聽who recently published on critical health complications from exposure to aflatoxins and fumonisin鈥� both are mycotoxins produced by molds. Exposure to mycotoxins much above regulatory guidelines substantially increases mortality and morbidity, and can cause acute poisoning, cancer, and, most recently noted, is a contributor to stunted growth in children of affected populations. The working group published recommendations to reduce exposure in developing countries in the report聽. In an聽聽with 杏吧原创 University, Miller stated that, 鈥渋mproving mycotoxin control could have a far-reaching health benefit. It is time to put the existing knowledge and technology into action to control mycotoxin food contamination in low-income countries.鈥�

Miller鈥檚 long-term fundamental interest in fungal metabolites applies to various ecosystems and populations, including people, animals, and insects, as related to mortality, morbidity, or increasing allergic response, 鈥渋t鈥檚 all the same [question]: what are the chemicals that these fungi make, and what do they do?鈥�

And he says, you need to be persistent.

Miller is interested in large unanswered questions that are important to public health. 鈥淭hey take a long time, but they鈥檙e important, and that鈥檚 the challenge that I鈥檓 interested in.鈥� Miller recalled epidemiological data that emerged in Canada in 1989/90 that showed that children who lived in moldy houses would be more likely to develop allergies to everything; 鈥渁nd that made no sense, so no one believed it. And I thought, 鈥榯hat鈥檚 either completely wrong, or there鈥檚 something we don鈥檛 understand.鈥� The short answer is, it was true.鈥� The mechanism took over 20 years to find, but this information has allowed the guidelines used in industrial hygiene, public health and more recently for clinicians to better advise their patients.

Miller has served on many national and international committees regarding built environment mold and dampness. He currently serves on the American Academy of Allergy Asthma & Immunology committee producing practice parameters for environmental allergens. Additionally, he is an elected member of the International Academy of Indoor Air Sciences, and a Fellow of the American Industrial Hygiene Association. His expertise in indoor air quality and mold connected him with Dr. Tom Kovesi, Research Institute Pediatric Respirologist of Children鈥檚 Hospital of Eastern Ontario (CHEO). Together with the community members of Cape Dorset, Nunavut, Miller and Kovesi investigated the association between indoor air quality and respiratory health. Specifically, Inuit infants have extremely high rates of lower respiratory tract infection (LRTI), and examining data on the indoor air quality of their housing identified and classified risk factors for LRTI. This preliminary study enabled a much larger study of many communities as well as a ventilation intervention study. The results highlighted that low per person ventilation was a major risk factor but more importantly allowed officials to support the investment of improved ventilation systems within the homes.

In the case of Nunavut, the research team knew there was a problem, and felt that the existing common wisdom wasn鈥檛 plausible. It took a lot of time, resources, and efforts to find an answer, but 鈥渢he research had to be done.鈥�

And he says you need to be genuinely curious.

After a 20-year collaboration and partnership with J.D. Irving Ltd. (JDI), the Natural Sciences and Engineering Research Council (NSERC) announced the 2015 NSERC Synergy Award for Miller following their discoveries that will reduce impacts of the eastern spruce budworm on North American forests. The eastern spruce budworm is the most damaging forest insect in the country, with a historical outbreak affecting 50 million hectares. Miller鈥檚 work with JDI led to the discovery of an insect toxic strain of endophytes, a natural fungi, in the needles of conifer seedlings in the Acadian forest. The endophytes can be transmitted to seedlings as they grow from a ground surrounded by cast needles from mature trees; these seedlings grow into trees with an increased tolerance to the spruce budworm. Foresters now have an effective and environmentally sustainable tool. In his聽聽with 杏吧原创,聽Miller noted, that 鈥渘one of this would have been possible without lots of different kinds of expertise. This award reflects a lot of work by a lot of people over a long of time.鈥� Further, he acknowledges that an interdisciplinary approach to research is critical to produce significant results; 鈥淪cience is a team sport.鈥�

For Miller, it鈥檚 always been about asking questions, getting resources, and finishing a commitment. He also stresses the success that will inherently follow from asking the right question. 鈥淲hen you have no idea why something is happening, 鈥� you have to ask the right question at the beginning, get an answer, and make a decision about what the next question will be.鈥�

When Miller is asked which project has left a lasting impression, he shakes his head and says that there鈥檚 not simply one that stands above the others. 鈥淚t still matters to me that I鈥檓 working on something that will make a difference. I do this because it matters.鈥� His continued inspiration and motivation comes from the desire to 鈥渋mprove lives and impact people鈥� I don鈥檛 know why else we would do it.鈥�

Here for contact information for聽David Miller.

by David McMullin, Department of Chemistry, 杏吧原创 University

One of the most fascinating aspects of fungi is their ability to synthesize an array of structurally diverse, often potently bio-active compounds known as secondary metabolites. This phenomenon can be exemplified by Sir Alexander Fleming鈥檚 discovery of penicillin from an indoor Penicillium species, or our exploitation of these chemicals as pharmaceuticals including the cholesterol lowering statins. There is a growing body of evidence from large population studies that demonstrates individuals living or working in damp and mouldy buildings are at an increased risk of developing allergies and respiratory symptoms, including asthma.

Modern buildings are designed to be more energy efficient with lower ventilation rates compared to the buildings constructed 40 years ago. Many of the commonly used building materials today, including particle board and paper-faced gypsum wallboard, will become water saturated with much less water as opposed to wood and traditional plaster. This unwanted water indoors can originate from daily routine activities such as cooking and showering, undetected leaks or flooding. When the amount of water vapor in a building exceeds the buildings ability to remove it, it is absorbed by the building materials. When these building materials become damp, mould growth occurs. This is of particular importance to individuals from industrialized countries, including Canada, as we spend the majority of our time indoors

The specific fungi, or moulds that are found on damp building materials is related to 鈥榟ow damp鈥�, the amount of time they remain damp and 鈥渘utrients鈥� of the particular building material. As different commonly used building materials have their own unique combination of available water, nutrients and chemistry, it is not surprising that specific moulds are associated with certain materials. While the overall species diversity of fungi is considered great, the number of species found indoors is fairly small. Interestingly, as similar building materials are used in industrialized countries, the distributions of some of the more common moulds in temperate environments are also very similar.

Gypsum board is often used to construct interior walls and ceilings; however, when it becomes damp it promotes the growth of numerous moulds. The most commonly identified indoor mould, Penicillium rubens, is illustrated and is the species where the antibiotic penicillin was originally discovered from.

Since the changes in construction practices for buildings and homes in the 1970鈥檚, evidence from large epidemiological studies conducted in multiple countries has shown that indoor exposures to dampness and moulds are associated with an increased risk for respiratory symptoms, asthma, bronchitis, respiratory infections and other non-specific symptoms. For example, the inflammatory disease asthma is commonly associated with a genetic predisposition known as atopy. However, individuals working or inhabiting a damp, mouldy building are at an increased risk for developing asthma. As a genetic predisposition and an allergy cannot explain this disease pattern, it suggests that there is a toxic effect. The production of toxic fungal secondary metabolites may explain why individuals are developing (non-atopic) asthma and other respiratory symptoms. As many of these secondary metabolites are not volatile, it additionally indicates that the exposures we experience are due to the inhalation of mould spores and mycelial fragments which harbor these biologically active chemicals.

To ask the question, 鈥渉ow do toxic secondary metabolites produced by moulds alter human lung biology?鈥�, information on the identity of the moulds found indoors and the preparation of the toxic chemicals they produce are first required. During my graduate studies in Professor David Miller麓s group, mould samples were collected from across Canada representing some of the most commonly identified fungi indoors. The goal of my research project was to purify the dominant secondary metabolites produced by these moulds so they could be tested for biological activity in relevant toxicological experiments. This type of work is necessary as one cannot typically go to the store and purchase these chemicals, you have to isolate them from nature yourself. The unambiguous confirmation of specific secondary metabolites from a particular species can often help fungal taxonomists, as the production of these chemicals is typically consistent within a particular species.

What I found investigating the secondary metabolites produced by some of the most frequently identified fungi in damp buildings ranged from the confirmation of potently toxic compounds known to be produced by certain species to the identification of new-to-science chemicals. Growing liters upon liters of fungi in liquid can be messy, stinky work鈥ut it is a lot of fun. So, after extracting all of those liters of fungal culture, isolating the secondary metabolites and identifying the structures by various spectroscopic methods; I was left with a collection of fungal metabolites produced by the actual moulds found growing in Canadian buildings and homes.

Chemical diversity of the secondary metabolites produced by moulds found in damp buildings. Many of these toxic compounds have been studied for their inflammatory properties in relevant toxicological experiments.

A broad consensus has been reached by national (e.g., Health Canada) and international (e.g., World Health Organization) agencies on the impact of mould and dampness in buildings. With these pure metabolites, we can contribute to an understanding of the role they play in the documented health effects of those working or living in damp and mouldy buildings. At the very low exposures that could be experienced by the human lung indoors, induction of pro-inflammatory genes, acute inflammation and histopathological disruptions have been observed in relevant models by fungal metabolites, including many of the metabolites isolated during my graduate research. While there are some differences between various models, all results indicate that the compounds present on mould spores that we are exposed to in damp buildings are potently pro-inflammatory. The physiological mechanism of inflammation and immuno-modulatory effects caused by these fungal metabolites are still poorly understood in lung cells. These types of experiments have revealed that these toxins modulate genes involved in asthma at concentrations experienced in damp and mouldy buildings by the human lung. A concerted effort on this important human health research will contribute to a more comprehensive understanding for non-atopic asthma and other documented adverse health effects associated with indoor mould exposures in humans.

For more information, please see:

Miller JD and McMullin DR (2014) Fungal secondary metabolites as harmful indoor air contaminants: 10 years on. Applied Microbiology and Biotechnology, 98: 9953-9966.

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