Does A Robust Immune System Lower Heart Attack Risk?

Higher levels of certain antibodies in the system are associated with lower risk of cardiovascular events, particularly coronary heart disease, in patients with hypertension, according to a new Imperial College London study.

In comparing more than 19,000 patients from the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) with matched controls, the researchers sought to explore whether measuring the levels of the antibody immunoglobulin G (lgG) and immunoglobulin M (IgM) levels provides any improvement in determining risk in hypertensive patients.
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The investigators analyzed blood levels of total lgG and IgM, evaluating blood levels of antibodies against an oxidized form of low-density lipoprotein (LDL) cholesterol, which is known to promote atherosclerosis. Ultimately, the authors found that high levels of total serum lgG, and to a lesser extent lgM, were “strongly associated with freedom from coronary events,” in addition to determining that antibodies against one type of oxidized LDL conferred protection, but the effect was weaker than with total immunoglobulins.

Further studies are needed to explore the relationship between these antibodies and the risk of coronary heart disease in other patient populations, such as those at a lower general risk and those with high cholesterol, said Ramzi Khamis, MBChB, DIC, PhD, MRCP, FESC, a consultant cardiologist at Imperial College London and lead study author.

Once such studies are performed, and if these results are confirmed, “the inclusion of antibody levels in risk profiling, as well as other risk factors such as cholesterol levels, diabetes, age, blood pressure, and smoking status, may provide more accurate stratification so that patients are more confident about their cardiovascular risk, and can act on it,” Dr Khamis said.

“People at higher risk of coronary heart disease can work on their modifiable risk factors,” continued Dr Khamis, “such as eating healthy food, exercising, and, importantly, avoiding risky behaviors such as smoking.”

While the data from this research “link a robust immune system to protection from heart attacks, we do now know what causes the differences on immunoglobulin levels between individuals,” added study coauthor Dorian Haskard, MD, a professor of cardiovascular medicine and head of the Division of Immunology and Inflammation at Imperial College of London.

These factors could be genetic, early-life events such as infections or nutrition, or ongoing, Dr Haskard said, also noting that further research is needed.

“It’s too early to affect general practitioners’ judgments, as [this study’s results] need validating in other patient cohorts,” he said. “Therefore, our paper can be viewed as a heads-up on what may be to come.”

—Mark McGraw

Reference

Khamis RY, Hughes AD, Caga-Anan N, et al. High serum immunoglobulin G and M levels predict freedom from adverse cardiovascular events in hypertension: a nested case-control substudy of the Anglo-Scandinavian Cardiac Outcomes Trial [published online June 19, 2016]. EBioMedicine. doi: http://dx.doi.org/10.1016/j.ebiom.2016.06.012.