Researchers at The University of Texas Health Science Center at Houston (UTHealth) have been awarded nearly $1 million to investigate Adenovirus-36 (Ad-36) infection as a novel risk factor for obesity. The grant is being awarded by the Federal Emergency Management Agency (FEMA)'s Assistance to Firefighters grant program.
The study will examine the relationship of Ad-36 to obesity and cardiovascular disease (CVD) risk factors and will provide information to design health and wellness strategies specifically for firefighters, who are more likely to be overweight or obese than the general population.
"Knowledge of Ad-36's role would add a new dimension to the multifactorial model of obesity," said Susie Day Ph.D., principal investigator and associate professor of epidemiology at The University of Texas School of Public Health, a part of UTHealth. "We must understand the causes of excessive weight among firefighters and reduce their CVD risk because America depends on these 2 million individuals' responsiveness to emergencies." Day is also a nutritional epidemiologist with the UTHealth Michael & Susan Dell Center for Healthy Living.
To date, the national obesity epidemic has mainly been explained as the interactions among genetics, food intake, physical activity and the environment. However, new evidence indicates a strong association between Ad-36 infection and obesity in humans and suggests that a subset of obesity may be caused by Ad-36. "We do know that Ad-36 has been found in about 30 percent of obese people compared to only 11 percent in people with normal weight," said Day. "However, even in the normal weight population, those infected with Ad-36 were heavier than those who were not infected."
Ad-36 infection, which has no known symptoms, has been associated in animal models with lower levels of serum cholesterol and triglycerides, which suggest possible implications for cardiovascular disease risk. This will be the first time mechanisms to explain the increased body fat, obesity hormones and lipids will be explored among humans in this study of firefighters, according to Day.
There are 56 different types of known adenoviruses, but Ad-36 is the only virus that is associated with weight gain and obesity in humans, according to Cynthia Chappell, Ph.D., co-investigator and professor of environmental health at the School of Public Health. "Other adenoviruses cause colds, diarrhea, or eye infections but none of these symptoms have been seen in animals infected with Ad-36. Until now, we haven't had a way of studying early Ad-36 infection in people because of a lack of symptoms," said Chappell, who is also a microbiologist with the UTHealth Center for Infectious Diseases.
Researchers are hoping to learn more about the virus by pinpointing the gene E4orf1, which is found in the virus and believed to cause the weight gain effect. "We are just beginning to understand how this virus works mainly by using laboratory studies with fat cells infected with Ad-36," said Chappell.
Obesity is a risk factor for CVD, and is one of the priority issues in the National Fire Service Research Agenda developed by the National Fallen Firefighters' Foundation. According to a 2011 study in The Journal of Occupational and Environmental Medicine, the prevalence of excessive weight in the fire service ranges from 77 percent to 87 percent, much higher than the national average. In 2009, the National Fire Protection Association reported 42 percent of on-duty fatalities that year were due to sudden cardiac death. According to Day, the most common overall cause of firefighter fatality is sudden cardiac death. She says the results of this research will greatly benefit the fire service.
"We have a top-notch team of scientists and an incredible opportunity to learn a great deal about this virus and how it works in people," said Day. "We are grateful for the chance to work with firefighters who are always called on for heroic feats. Now we'd like to do something for their health!"