Asthma Mysteries: What do we know about how non-allergic triggers impact asthma?

There are a lot of mysteries still yet to be solved when it comes to asthma. Not only do we as patients have a lot of questions, so do researchers! As evidence, I even found a question mark in the title of a journal article today—how’s that for “We honestly are not sure here”? This article—in the Opinions in Allergy segment of a 2009 issue of the Journal of Clinical; Experimental Allergy1—addresses the cause of intrinsic, or non-allergic, asthma in the following way:
Intrinsic asthma: not so different from allergic asthma but driven by superantigens?
Yes, that’s a question mark there. In research that cites 54 other works—clearly, we do not know this answer completely. So, here’s what we know about the asthma mystery of non-allergic asthma triggers.

What are non-allergic asthma triggers?
Allergic responses are caused by a compound in our bodies called IgE (immunoglobulin E). People with allergic asthma, or allergies, have higher levels of IgE present in their body (measured by a blood test). Conversely, any trigger that is not an allergic trigger—for instance, viral infections, humidity, cold air, chemicals or fragrances, aspirin, etc.—is known as a non-allergic trigger.
If you have a negative skin test for allergies, you have non-allergic asthma (like me, for the most part). 1

Who has non-allergic asthma?

According to the article above, about 10% of people with asthma have non-allergic asthma. In patients with difficult to treat (or difficult to control) asthma, 30% of these individuals indicate that they have non-allergic asthma1—so, their problems are not caused by allergies. Allergies are not necessarily easy to deal with, but when allergens are avoided, it is easier to have a clear-cut course of action for treating asthma. Severe asthmatics are more likely to be affected by non-allergic asthma,1 although many people with severe asthma have significant allergy components to their asthma.

So what’s the deal, exactly? (Or, what it could be.)

Researchers suggest that non-allergic asthma may be caused by these so called superantigens (which I imagine as some kind of cell or something, except for wearing a cape). It is considere that these superantigens present in the body essentially “switch on” an allergic response via Staphylococcus aureus bacteria in the lungs (or, perhaps another bacteria)1. This then causes these superantigens to develop, and a localized (inside the lungs, not systemically—throughout the whole body, within the blood) IgE response causes a sort of allergic response. This would be why skin tests and blood tests do not indicate an IgE elevation to indicate an allergic response—as it is not a true allergic response, but potentially, an allergic-like response in response to a non-allergen.

Allergens are caused by specific type of proteins 2,3—these are not present within the non-allergic inhaled triggers that cause asthma to flare up. It might also explain why the typical allergy symptoms experienced with grass or pollen allergies, for example, like itching, watery eyes, scratchy throat, etc., are not experienced in response to a non-allergic trigger with asthma—only the lungs are impacted, which could support the claim for a localized IgE (or “allergic-like”) response.

To continue, another study notes that the lack of a specific IgE response (to a specific allergen, like dogs or birch pollen, for example) does not necessarily mean people with non-allergic asthma will not have a higher serum (blood) IgE—rather, a slightly elevated IgE level may be present in individuals that have non-allergic asthma.4 So, this may also make individuals with non-allergic asthma more prone to having the responses detailed above. For these reasons, the use of anti-IgE biologic therapy (Xolair) is being investigated for its effects in asthma control for individuals with non-allergic asthma—with, per one study, fairly positive results 5.

Well… I guess we know what we don’t know? For now, it’s still a mystery of life… Just like much of living with asthma!

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