THE MICROBIOME SUMMIT : The New Path to Health
Invisible Microbial World of the Built Environment
Dr. Chris Lowry, PhD
There’s a large global trend in urbanization, and there are also large increases in inflammatory disorders. Coincidence? In this interview, Dr. Chris Lowry will discuss the microbes in our built (indoor) environment. Given that we spend approximately 90% of our life indoors, it is important for us to understand how the microbiome of the built environment affects our health.
- TRACEY:
- We are here today with Dr. Chris Lowry from the University of Colorado, Boulder. Thank you for joining me here today, Chris.
- CHRIS:
- You’re welcome. It’s a pleasure to be here.
- TRACEY:
- You have been doing some really interesting work in helping us to understand the built environment, what is happening within, you know, where we live and our office buildings and where we work and what kind of microbial world that we can’t see but is happening all around us and influencing us. Can you explain a little bit about why we’re studying this and how it’s shifted over the last 100 years?
- CHRIS:
- Sure. First, it’s important to point out that in modern, urban societies we spend – it’s estimated that we spend approximately 90 percent of our time indoors. So, if you think about your own daily schedule including sleeping I think you’ll find that that’s probably pretty accurate. So, given that the majority of our time is spent indoors it’s important to understand how the microbiome of that built environment may be impacting our health. There’s a couple of really good examples now of where the microbiome of the built environment seems to be impacting human health. One is a series of studies that have demonstrated that having a dog in the family alters the microbiome of the built environment and when dogs are present during early life have protection against allergic disorders later on in life. Another really good example is a study that was just recently published and this group looked at two populations. One is the Amish and the other is the Hutterites. These two populations have similar backgrounds in terms of where these populations came from but they have different levels of adoption of modern farming practices. So, the Amish tend to have animals, farm animals very close to where they’re living and sleeping and this is not so much the case with the Hutterite populations that have adopted more modern farming techniques, by and large. What this group showed is that taking dust samples from the homes of, or the built environments of these two populations they found that the dust from the built environment of the Amish could protect against allergic asthma in mouse models. Whereas the dust from the Hutterite built environment could not. They went on to show that this is mediated in part through effects of this dust on innate immune systems and really provides a basis for how the microbiome of the built environment, in other words the dust that’s present where we live, can have a very serious impact on how our bodies respond in terms of immunologic responses to different types of stimuli.
- TRACEY:
- So fascinating. Wrapping our heads around the fact that we are our own microbiomes and we, in fact, have several microbiomes going on simultaneously on our bodies, but now we’re thinking about the microbiomes, in our offices, in our homes, where we sleep, and these microbiomes are having influences on our immune systems.
- CHRIS:
- That’s right. And, the microbiome of our homes is different from the microbiome of our offices and microbiomes in one city can be distinguished from microbiomes in another city. One very important part of the microbiome of the built environment which we talked about in a different session is the microbiome that comes from our drinking water and this is turning out to be important because we, of course, consume that water either by breathing in shower aerosols or drinking the water itself. That water by no means is sterile but the fact that it’s not sterile doesn’t mean that it’s not healthy. And as long as the microbiome that is contained within the water doesn’t have overt pathogens it’s very likely that the microbiome in that water is helping to train our immune systems and one case in point is we know that the abundance of mycobacteria in municipal water sources tends to be very high and we associate the presence of mycobacteria with the old friends hypothesis and protection from inappropriate inflammation. On the other hand, some water sources contain specific species or strains of mycobacteria that can actually cause infection. So, there’s two sides to that story. One is mycobacteria can be protective, particularly against chronic inflammatory disease. On the other hand, if you’re unlucky and your particular water source has high abundance of these potential micro bacterial pathogens, which are called non-tuberculous mycobacteria, or NTM infections, then obviously that has negative health outcomes.
- TRACEY:
- My understanding is we need to start thinking about, you know, our microbiomes in the built environment from the old friends hypothesis but we have an opportunity too to maybe manipulate what these microbiomes might look like. I know you were doing some interesting research on perhaps what would it look like to bring a probiotic into the ecosystem of the built environment. We think about ingesting them but what about in our buildings?
- CHRIS:
- You could imagine a time when you could buy a probiotic that you could then spray on surfaces in your homes and I say that because there are already products available commercially that are marketed for that purposes, not evaluated by the FDA however, I must add. And so I think the point of saying that is people are already thinking that way, that we can take control over the types of bacteria that are on surfaces in our homes and so this is a case where probiotics are not being ingested in a pill or part of a fermenting food but they’re being dispersed throughout the home. So, that’s one strategy. Another important factor about the microbiome of the built environment is something called microbial diversity. Microbial diversity is really an important concept. If you think about most ecosystems, if you think about a rain forest, for example, a rain forest as an ecosystem is healthy because of, in part, the tremendous diversity of organisms that inhabit that ecosystem. If you contrast that, for example, with a monoculture of a single species that monoculture is not healthy in the sense that it’s highly stable and resilient. The microbiomes of our bodies and the microbiomes of the environment are similar. Higher diversity tends to translate into greater stability, greater health benefits and if you think about the microbiome of the built environment one way to affect the diversity of that environment would be to open up your home to the outdoors because the outdoors is a tremendous source of microbial diversity. But there’s a bit of a give and take in the engineering field because there’s been a huge focus on essentially sealing up our homes to the extent possible to avoid outdoor air entering the homes because it’s not energy efficient. Right? So, if you have lots of leaks in the walls of your home that would allow outdoor air to come in, that requires more heating, more energy use, or in the summertime more cooling if you have air-conditioning. But it may be that by doing so you’re limiting the transfer of outdoor and indoor microbiomes which may not be particularly healthy. Like, modelling suggests that that type of weatherization of homes, while saving costs in terms of energy use, may actually increase costs much more so due to medical costs to cover the medical consequences of having a stagnant indoor environment.
- TRACEY:
- Right. I think that stat you gave as well about 90 percent of us spending our time indoors is a really important one too. And if we want microbial diversity perhaps we have to start spending more time outdoors in nature to get that microbial diversity, especially if we can’t necessarily change the office building that we live in but, perhaps going outside and experiencing that park that’s down the street might be one way to get that microbial exchange happening.
- CHRIS:
- And this raises questions about how we design our communities. I think we can conclude that not everyone has the same level of access to those outdoor parks. And particularly in socioeconomically disadvantaged areas, inner-city areas, individuals may not have the same level of access to healthy soils, healthy outdoor air, as someone living in the suburbs or in the countryside. And so, those are questions that we need to deal with at a societal level to make sure for maximal health benefits we do have access to these green spaces.
- TRACEY:
- Yeah, absolutely. I mean, you could imagine that there are people being born today that are born in a sterile operating room via C-section and taken to their high-rise building and live their especially Canada in the winter. I mean, they’re living their first six months without really being exposed to the outdoors and we need to start shifting our understanding our habits that it’s really important for us to have those exposures. And to look at our public policies, as we’re building our cities and building our buildings.
- CHRIS:
- There’s a few proxies that are available for actually being outdoors. One is opening the window so you can have outdoor air inside the home. Another is bringing animals into the home that increase biodiversity inside the home life, like pets, like dogs, and another is bringing fresh fruits and vegetables into the home and obviously consuming those fresh fruits and vegetables or having plants inside the home.
- TRACEY:
- So, Chris, from what you’re saying it sounds like we have to be thinking about our built environments and its ecosystem diversity that way. Because the microbial exchange for our immune regulation is really important.
- CHRIS:
- That’s right. This effect of the environment on our health is so strongly supported based on observations in Europe. You know, the health benefits of growing up on a farm is actually called “the farm effect” because the health benefits of that type of environment are so clear and then the question is how do we construct our homes and other living spaces so that we can essentially retain that farm effect and benefit from what other factors are contributing to those health benefits.
- TRACEY:
- Absolutely. Thank you so much for sharing all your knowledge with us today.
- CHRIS:
- You’re welcome. It’s been a pleasure.
