An Air of Danger
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Aruni Bhatnagar, a pioneer in the emerging field of environmental cardiology, leads a U of L research team that is studying a possible link between air pollution and heart disease.
Did you ever watch someone in running shorts or sweats take a vigorous sprint beside a busy street and wonder if the exhaust they huffed counteracted the positive benefits of their exercise?
If so, your suspicion may be well founded.
Many people run as part of a heart-healthy life regimen. Yet many runners and non-runners with no apparent risk factors develop heart disease.
People can eat right, exercise, reduce their stress and have other heart-disease risk factors such as genetic makeup, gender and age analyzed and accounted for by their doctors. And they still have heart attacks.
Scientists now know that as many as 50 percent of patients with heart disease have no discernable risk factors. None, that is, besides frequent exposure to certain pollutants.
According to Aruni Bhatnagar, a professor of medicine in the Division of Cardiology at U of L, various studies over the last decade have shown a link between air pollution and daily mortality rates.
"We know that on days when there is a significant increase in the particulate air pollution, there is about a 6 percent increase in mortality over the next 24 hours—most of those being cardiopulmonary-related deaths," Bhatnagar explains.
"Of the 300,000 sudden cardiac deaths (in the United States) each year, it is now estimated that 60,000 to 80,000 of those may be linked to pollution."
In some of the world's smoggiest cities, according to a report published in 2000 by the World Bank, breathing the air is comparable to smoking two packs of cigarettes a day.
Bhatnagar and his colleagues at the National Institute of Environmental Health Sciences (NIEHS), the National Heart, Lung and Blood Institute and the Environmental Protection Agency, were aware of the growing evidence of a relationship between pollution and heart disease. Yet, they wondered why so few studies had been done to see if specific air pollutants affected the heart.
"There have been many studies regarding the causal relationship between pollution and cancer, pollution and asthma," he says. "When we already know that there is a connection between pollution and heart disease, why had no one looked at it more closely?"
So in 2002, Bhatnagar helped organize a workshop on the role of environmental agents in cardiovascular disease. There, some of the main questions of a new discipline, dubbed "environmental cardiology," were hashed out.
What specific toxins, for instance, lead to an increased severity of heart disease? Can they be identified, and how? And what factors make some patients more susceptible to pollutants than others? The NIEHS, other agencies and scientists at the workshop agreed that studies would be needed to answer these questions.
"The field of environmental cardiology is a new, exciting area of research," says Dr. Roberto Bolli, chief of U of L's cardiology division and a professor of medicine, physiology and biophysics.
"Dr. Bhatnagar must be credited with having spearheaded this field and for positioning himself as a leader nationwide," Bolli adds. "The implications of environmental cardiology are potentially huge, as environmental pollutants and toxins are ubiquitous and have a major impact on cardiovascular disease."
To support their work in environmental cardiology, Bhatnagar and U of L collaborators recently received the university's first-ever NIH Program-Project Grant (PPG). The $7 million five-year award will fund four projects as well as related core services and laboratories.
"To be selected as the scientific birthplace for environmental cardiology—an entirely new discipline—demonstrates the level of research excellence and national recognition that U of L has achieved," says U of L President James Ramsey.
The principal investigators of the PPG projects cover a range of research disciplines. Along with Bhatnagar in cardiology, they include Stanley D'Souza, physiology; Sumanth Prabhu, cardiology; and Russell Prough in biochemistry.
All four projects involve determining the various effects of different aldehydes on the heart's cells and function. Aldehydes are a group of chemicals found in high quantities in vehicle exhaust fumes and cigarette smoke. In most cities, aldehydes make up more than 50 percent of air pollution particulates.
The projects seek to answer four basic questions:
- How do heart tissues process aldehydes and how does the cardiovascular system handle the challenge of foreign chemicals?
- How, and how quickly, do aldehydes accelerate the progression of heart disease?
- How do aldehydes interact with blood cells to cause inflammation of the heart and blood vessels?
- How do high-levels of aldehydes raise the risk of heart attack and worsen heart failure?
A key element to the success of the projects and to winning the PPG award is the presence of leading-edge core laboratories. U of L's bioanalytical core laboratory, directed by William Pierce, will analyze molecular structures for all four projects using mass spectrometers. An additional core lab to test exposures to inhaled pollutants is managed by the University of Alabama at Birmingham. Jewish Hospital will provide additional lab support.
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Air pollution and heart disease studies require the interdisciplinary expertise of U of L medical researchers (from left) Sumanth Prabhu, Russell Prough, Aruni Bhatnagar, William Pierce and Stanley D’Souza.
Unlike most NIH awards to individual investigators, Bhatnagar explains, PPG recognition is important because "it is awarded to institutions that show a collection of leading investigators who work collaboratively to approach a question from many sides."
He adds, "It raises the academic and scientific bar not just for the participants, but for the entire university."
"This is one of the most prestigious grants ever awarded to the University of Louisville," says Dr. Joel Kaplan, executive vice president and chancellor for health affairs. "It is nationally very competitive, and we are very proud of this distinguished group of researchers.
"U of L is now the home of environmental cardiology, and this research should lead to an improved standard of living for all people in the polluted Ohio River Valley."
