Heart disease remains the number one killer globally and in the United States. Experts from the Mount Sinai Institute for Exposomic Research explain how studying the environment can help prevent and better treat cardiovascular disease
Discussion
We spoke with Michal Hadley, MD, Maayan Yitshak- Sade, PhD and Allan Just, PhD of the Institute for Exposomic Research at Mount Sinai about how they’re applying exposomics approaches and methodologies to study cardiovascular disease risk and prevention. Read the full interview transcript below.
How does cardiovascular disease and exposomic research integrate?
Dr. Hadley: “Cardiovascular disease remains the number one killer globally and in the United States. There are millions and millions of deaths around the world from cardiovascular disease. About 11 million of those are probably due to environmental factors and that’s where exposomics can make a huge impact. Cardiology and cardiovascular disease, maybe more than any other medical specialty, has an enormous foundation of evidence based on clinical trials going back decades, but, the problem is that a lot of those studies have focused really on the individual risk factors. They haven’t really looked at how the environment affects cardiovascular health and leads to cardiovascular disease. We know that all of those traditional risk factors, genetic things like a predisposition for hypertension only account for a fraction of the total burden of cardiovascular disease. The other part of that, the other driver of cardiovascular disease is the environment. It’s something we don’t understand very well, but now with the new technology and new researchers, like those at Mount Sinai, we’re getting a better understanding of exactly which environmental exposures are precipitated in cardiovascular disease and what we can do to mitigate those exposures and improve cardiovascular health”.
Dr. Yitshak-Sade: “We’re studying how environmental exposures, such as air pollution, climate, noise, or greenness around the house, affects the risk of cardiovascular diseases, such as stroke or acute heart attacks. Cardiovascular disease is rarely attributed to a single cause. When we study cardiovascular disease in the context of exposomic research, we can incorporate multiple exposures and assess the contribution of numerous exposures to the development of cardiovascular disease. Cardiovascular disease development can be attributed to lifestyle and behavior factors such as diet, physical activity, smoking, environmental exposures, social, racial, and ethnic environment, as well as socioeconomic status. Because we can’t attribute cardiovascular disease to a single exposure, when we study the environmental effects on cardiovascular disease, it is important to take many exposures into account. Exposomic research allows us to measure multiple exposures, just as it behaves in the actual environment, and see how these exposures affect cardiovascular health”.
Dr. Just: “Exposomics and cardiovascular disease research is the consideration of all of the exposures in our physical and social environment that contribute to our health or disease. I’ve always been interested in environmental exposures and how they contribute to human health. And as my research has moved towards air pollution, we know that that’s a major contributor for cardiovascular disease and cardiovascular events. Exposomics can broaden out our consideration of all the lifestyle factors that it’s not just individual behaviors, but we start to understand the context of these physical and social exposures are also related to where you live, the community in which you reside and where you go to school, where you eat, where you play”.
Explain how your research works
Dr. Hadley: “We’re very interested in understanding how air pollution may precipitate heart failure. It’s been seen in animal models that air pollution exposure can cause inflammation and fibrosis of the heart, but that hasn’t been seen yet in humans. What we’ve done is developed a database of thousands of MRIs collected here at Mount Sinai and analyze them to understand whether there’s inflammation or fibrosis in those individuals. And then we’re pairing that with data on those individuals air pollution exposures, collected by faculty at the Institute for Exposomic Research and together that will tell us whether or not air pollution may be causing inflammation in human hearts and precipitating heart failure”.
Dr. Yitshak-Sade: “In my lab, we use exposure models based on satellite data and other measures of the built and natural environment, to measure environmental exposures such as air pollution, temperature, the amount of greenness around the house, the walkability in the neighborhood, or proximity to roads. We’re then linking them to national routinely collected health data, such as the Medicare data for example. We’re also linking data on socioeconomic and racial features of the environment. To combine all this information, we’re conducting big data analysis to assess the effects of these different exposures on cardiovascular morbidity and mortality”.
Dr. Just: “we’re looking at how exposure to environmental pollutants and my lab does a lot of work on fine particulate matter which are very, very small particles that can go deep into the lungs and into the bloodstream, how those can impact human health across the life course. We’re also looking at how variation in temperature, those really hot days and variation in humidity, where it’s very hard for you to cool down, can trigger cardiovascular events like heart attacks and strokes. A lot of my work has been to understand the patterns of exposure. Instead of assuming that everyone is exposed to the same thing, really diving deep at trying to reconstruct what people have breathed in or what they’ve experienced. And as we reconstruct that exposure, we’ve been able to see that there’s large variation and it varies from community to community, from block to block. My lab pulls data from many sources. We use satellites from NASA, from NOAA, the US geologic survey and the European space agency. We bring down enormous quantities of data because it lets us reconstruct what was happening everywhere at all times, over large regions. We have models that reconstruct air pollution across the entire continental United States. We use billions and billions of measures that have been collected from these satellites”.
What impact do you believe this research can achieve?
Dr. Hadley: “What excites me the most about exposomics is the potential for impact in cardiovascular disease. We have such a good understanding of individual risk factors, but we have a pretty limited understanding of how the environment drives health outcomes. And that creates a huge opportunity, and I think a responsibility, for clinicians to understand how the environment is influencing health outcomes and to learn what we can do to intervene for patients and populations. Currently I’m the United States representative to the World Heart Federation Air Pollution Expert Group. And I also do some consulting for the World Health Organization in terms of their air pollution and clinical training programs. So together, these groups are developing guidelines and policy statements that are published and distributed to policymakers and clinicians around the world. Our hope is that these policy briefs distributed to clinicians and policymakers will raise the consciousness about how the environment is impacting health. Oftentimes people have boiled health down to just individual choices and not the whole environment. And we want to change that thinking. And I think by showing real quantitative analysis, we can drive more resources to mitigate environmental exposures.
Dr. Yitshak-Sade: “What excites me most about our research field is that we do actionable research. Our findings can be translated into policy change that can then promote the health of communities. A good example is the national ambient air quality standards set by the EPA. These standards set air pollution levels that are considered safe by the EPA and air pollution emissions should not exceed these levels. Every few years, there’s a committee that evaluates all the research that was published in these years and try to determine whether these levels are indeed safe and not harmful for the population. So when we do studies that show that even lower air pollution levels are associated with mortality and with increased cardiovascular risk, this committee takes this research into account in the review of the standards and decides whether or not these standards needs to be changed”.
Dr. Just: “Our use of satellite data that have been collected now for several decades, it means that we’re able to go back in time and reconstruct what people’s exposures were before they developed a disease. This is one of the strengths of our exposure reconstruction. We can build out exposures for people that have already developed disease, but we’re able to go back in time, rolling back the movie to see what were they exposed to before they developed disease? Sometimes going back years into their past. This is a challenge for other kinds of studies that rely on collecting bio specimens or following people prospectively because they don’t know who will go on to develop disease. We hope that our work can impact policy and health in several ways. Really reconstructing where people are exposed and how much they’re exposed to air pollution and extreme temperatures can help drive interventions. We’re starting to talk more as a society about the importance of making sure that people have clean air and that people are able to stay cool during heat waves”.
How can the study of exposomics advance cardiovascular disease research in the future?
Dr. Hadley: “I think the dream is to bring exposomics to every individual. And that means being able to provide a personalized exposome for each individual, which means measuring all of these environmental exposures at the individual level. We’re going to see more granularity in terms of those measurements. It’s not going to happen all at once. It’s going to happen in a stepwise fashion where certain exposures that are more easily quantified and individualized, like air pollution, will be known sooner. And then farther down the road maybe things like your socioeconomic environment. We have to figure out the right metrics to quantify that and to individualize that, but over time we’re going to get a better and better sense of that. And that should, we hope, factor into management of preventing environmental exposures that can cause disease and treating disease as well.
Dr. Yitshak-Sade: “The future of exposomics is the inclusion of environmental exposures in cardiovascular risk assessment. Imagine a day that you walk into the doctor’s office and the doctor not only measures your blood pressure or asks you if you’re smoking, he or she will also have the tools to estimate to which environmental exposures you’re exposed to, and then tailor interventions according to this information”.
Dr. Just: ”I’m excited about thinking about more spatial resolution, of being able to really drill down on what happens where you live. We’re starting to do some work now where we’re going to estimate temperature down at the block level, not assigning one temperature to the entire city like you might see when you pull up a weather app on your phone, but really understanding how temperature can vary from block to block and neighborhood to neighborhood. I’m also very excited about new satellites that are measuring air quality and temperature from hour to hour throughout the day. This will let us better understand rapidly changing conditions as well as how air quality, and temperature and other environmental conditions can vary. We’re reconstructing exposure where you live and understanding rapidly changing weather and air quality conditions so that your doctor will be able to know when you have higher risks and we can tailor interventions, have precision public health so that the environmental exposures are considered as part of your risk profile. We hope that understanding your environmental exposures can lead to fewer heart attacks and fewer strokes”.
How can this research contribute to health equity?
Dr. Hadley: “I would like to be part of is a movement to bring health equity across the world. What that requires is leveling the playing field in terms of opportunity to have a healthy and productive life. The big missing piece, from my perspective, is understanding the environment. We’re getting good at understanding individual risk, genetic causes of disease, but in terms of how the environment drives poor health outcomes and what can be done about it, that’s a huge research question. I think it’s going to help us bring health equity across the world”.
Dr. Yitshak-Sade: “We know that minority groups experience worse climate and air pollution-related cardiovascular health outcomes. And these differential risks persist even after accounting for lifestyle and habits, such as smoking, physical activity, and diet. This suggests that the differences in these risks are attributed to other factors, such as limited access to healthcare, higher air pollution exposures, or it can be related to higher susceptibility to disease due to chronic stress. We’ve seen these worse environmental-related health outcomes in racial minorities, specifically black Americans, and in lower socioeconomic groups.
Dr. Just: “As we’re able to build higher resolution maps, our surfaces that reconstruct what people experience where they live, we’re unveiling the great inequity of social distribution in what people breathe and what people experience. We see as we get higher resolution exposures, that there’s great inequity, that the distribution of exposure is unfair and that lower income communities have higher air pollution burdens and experience more heat stress, more extreme heat waves in frequency, duration, and intensity in the summertime. Our work with satellites is revealing that we need this kind of high resolution reconstruction so that we’re not assuming that everyone in the city is really experiencing the same thing. We know that it’s much worse in certain communities and our work has linked, for example, extreme heat waves. We see that the temperatures are much higher in areas with greater social vulnerability. We’re able to show that environmental pollutants are part of the social disadvantage, this inequity that’s related to residential segregation and structural racism, the sighting of the kinds of societal factors that contribute to air pollution or extreme temperature. Where we’ve put our roadways and where we have asphalt versus trees really leads to an unequal distribution when we have bad air quality days or we have extreme heat”.