Is Atherosclerosis an Allergic Disease?

[Guest guest]

By: Kaiser | December 27, 2011 That was the title of a recent

commentary in *Circulation Research* by Christoph J. Binder, MD, PhD, and

ph L. Witztum, MD, from the University of California, San Diego (*Circ

Res* 2011;109:1103-04).

The two commentators were impressed by Wang et. al.'s research showing the

involvement of immunoglobulin E (IgE), which plays an important role in

allergic reactions, in promoting atherogenesis (*J Clin

Invest*2011;121:3564-3577).

IgE, in relation to allergic reactions, activates mast cells by binding to

IgE's high-affinity receptor FcER1. In addition to allergic responses, mast

cells participate in other inflammatory diseases, including

atherosclerosis, Wang and colleagues wrote.

For their study, Wang et. al. analyzed serum IgE levels in two separate

Chinese populations and found them elevated in patients with myocardial

infarction and unstable angina.

Those with acute MIs had the highest levels of IgE, followed by those with

unstable angina, and then those with stable angina. In other words, the

circulating levels of IgE correlated with plaque instability, Wang and

colleagues wrote.

In addition, the investigators found IgE and FcER1 in human atherosclerotic

lesions, mostly localized in macrophage-rich areas.

Prior studies had found that people with common allergic diseases such as

asthma and allergic rhinitis were more prone to develop atherosclerosis (*Arch

Intern Med* 2005;165:2521-6), suggesting a link.

But such detailed association of IgE with atherosclerosis had not been seen

before, Wang et. al. said.

And what it means is not entirely clear, Binder and Witztum wrote in their

commentary.

Nevertheless, " the evidence continues to accumulate supporting an important

role for immunological mechanisms in all phases of atherosclerosis, " the

commentators said.

There is a host of " combinatorial groupings " involving IgE and other

receptors that contribute to the " pro-atherogenic activity of IgE in

humans, " including macrophage activation and apoptosis, Binder and Witztum

said.

But they focused on the fact that elevated IgE levels typically reflect

allergic-type immune responses.

" It would be of great interest to know whether the increased IgE levels

were polyclonal or reflected any disease-specific antigens, such as those

to oxidation-specific epitopes characterized for IgG and IgM isotypes in

humans and murine models of atherosclerosis. "

A problem with the current study is that the levels of IgE were low

overall. Also, it is unclear whether the IgE levels were a cause or product

of the heart disease.

However, the evidence of IgE in atherosclerotic lesions and in serum from

patients with unstable plaque " support the notion that such 'minor'

immunoglobulin molecules may participate in the activation not only of mast

cells, but also other blood-borne inflammatory cells ... during the

pathogenesis of human atherosclerosis, " Wang and colleagues concluded.

--

Ortiz, MS, RD

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