Allergy research uncovers heart attack link
By Robin Arnette
People with allergies are less likely to have experienced a heart attack, according to a new study by scientists at NIEHS and SRA International. The research appeared online (http://www.ncbi.nlm.nih.gov/pubmed/22921873) Aug. 23 in the Journal of Allergy and Clinical Immunology and is the first to measure the presence of allergic antibodies in relation to past myocardial infarction (MI) in the U.S.
The work was based on laboratory data and questionnaires from the National Health and Nutrition Examination Survey (NHANES) 2005-2006, (http://www.cdc.gov/nchs/nhanes/nhanes2005-2006/nhanes05_06.htm) a cross-sectional analysis of the U.S. population developed in collaboration with NIEHS, the National Institute of Allergy and Infectious Diseases, and the National Center for Health Statistics. Using thousands of participants, the research team measured allergic antibodies, also known as allergen-specific immunoglobulin E (sIgE), that were specific to 19 allergens, and then examined the relationship between sIgE and self-reported past heart attack.
“We looked at it in a few different ways quantitatively, and any way we looked at it, we found an inverse relationship with past heart attack,” said corresponding author and NIEHS lead researcher Michael Fessler, M.D. “The findings are a preliminary step forward, but if our results are confirmed in a prospective study, this could lead to important clinical implications for how allergen exposure affects people’s risk for heart attack.”
Fessler said that the paper was based on studies of the adaptive immune system, or the body’s ability to develop memory for environmental molecules. He said adaptive immunity is largely driven by different immune programs that involve T helper (Th) cells.
Previous work from other laboratories determined that mice born with a Th1 immune program tend to develop atherosclerosis and other inflammatory diseases, while those with Th2 generally develop allergies and are protected from atherosclerosis. His group wanted to see if people who are allergic to food, grasses, pet dander, and other substances were less likely to have had a heart attack, based on the premise that Th2 allergic programming, as indicated by sIgE, might suppress the Th1 immune response required for atherosclerosis.
Since NHANES is a cross-sectional analysis of people in the country, Fessler and colleagues can’t definitively say that having allergies will protect someone from having a heart attack. Nonetheless, NIEHS Scientific Director and article co-author Darryl Zeldin, M.D., believes the findings are significant.
“The data are still intriguing, given that the relationship is independent of a long list of coronary risk factors, such as smoking, high cholesterol levels, hypertension, family history of MI, and diabetes,” Zeldin said.
Citation: Jaramillo R, Cohn RD, Crockett PW, Gowdy KM, Zeldin DC, Fessler MB. (http://www.ncbi.nlm.nih.gov/pubmed/22921873) 2012. Relation between objective measures of atopy and myocardial infarction in the United States. J Allergy Clin Immunol; doi:10.1016/j.jaci.2012.06.033 [Online 23 August 2012].