Understanding Eosinophilic Asthma

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illustration of eosinophil

You’ve just been diagnosed with eosinophilic asthma, but what does that mean? Most people are familiar with asthma, the chronic condition where the airways become inflamed leading to symptoms like shortness of breath and wheezing. However, not many realize that asthma isn’t simply one general disease. Instead, researchers now classify asthma into several different subtypes.  Identifying your subtype of asthma provides your doctor with important information in determining how to treat it. Eosinophilic asthma is often severe, so proper identification is especially helpful in getting it under control. Let’s answer some of the questions you may have.

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I have never heard of eosinophils. What are they?

It is hard to understand eosinophilic asthma if you don’t even know what an eosinophil is. Eosinophils are a type of white blood cell. They help protect your body against things like bacteria and parasites. They also play a role in your body’s inflammatory response, especially with regards to allergies. During an asthma attack, eosinophils travel through the bloodstream to your airways and release chemicals that can cause narrowing of your upper and lower airways, making it difficult to breathe.

How did my doctor determine I have eosinophilic asthma?

You may be diagnosed with eosinophilic asthma if you have a large number of eosinophils present in your sputum, your blood, or your lung tissue. A small amount of sputum, the thick material that you cough up from your lower airways, may be collected, or you may have a small sample of blood drawn from your vein. A more invasive procedure called a bronchoscopy, where a thin flexible tube is inserted into your nose or mouth to allow your doctor to visualize your airways, may be used to remove a small amount of tissue or fluid from your lungs. These specimens are then examined under a microscope. When a red-colored dye (eosin) is applied, the eosinophils stain brightly.

Some evidence suggests that greater numbers of eosinophils are linked to increased asthma severity and exacerbations of symptoms.

The following characteristics are often seen in people with eosinophilic asthma:

  • Severe asthma- According to the American Thoracic Society, severe asthma requires high doses of inhaled corticosteroids and other control medications such as systemic corticosteroids to prevent it from becoming uncontrolled, or it may remain uncontrolled even with this therapy.

  • Adult onset- Many patients with eosinophilic asthma don’t develop it until adulthood, though it may occasionally be seen in children.

  • Chronic sinus problems and nasal polyps- Patients may present with persistent sinus infections and painless, tear-drop shaped growths develop in the nose or sinus as a result of persistent inflammation. They may complain of stuffy nose, postnasal drip, and loss of smell.

  • No underlying allergies- Many asthma patients are allergic to things like pollen, smoke or pet dander, and exposure to them causes their asthma to flare up. However, this is generally not the case for eosinophilic asthma; it is not usually triggered by exposure to an allergen.

Will this diagnosis change how my asthma is treated?

Maybe. Some patients with eosinophilic asthma respond to the traditional methods of treating it, using inhaled corticosteroids to reduce inflammation and bronchodilators like albuterol as a quick-acting “rescue” medication. However, since eosinophilic asthma affects the entire respiratory tract, inhaled steroids are often not enough, and many patients require systemic oral steroids to see symptom improvement.

New treatments are also being developed to reduce the number of eosinophils in the airway. These may be a good option for you if your symptoms don’t respond to steroids.

  • Anti-interleukin-5 (IL-5) therapy- Interleukin-5 is a protein that activates eosinophils. Biologic therapies, such as mepolizumab (Nucala) and reslizumab (Cinqair), block IL-5. They are both used in conjunction with other asthma medications.

  • Anti-immunoglobulin E (IgE) therapy- Immunoglobulin E is an antibody that plays a role in allergic asthma. Therapies, like omalizumab (Xolair), that block IgE decrease both inflammation and the number of eosinophils in the airway. However, this treatment will only be effective for cases of eosinophilic asthma that are triggered by allergens.

  • Clinical trials- Researchers are studying other treatments that target interleukins, such as anti-IL-4 and anti-IL-13. Early results look favorable for these new therapies.

Is there anything I can do to help manage my asthma?

There are many things you can do to try and control your asthma symptoms:

  • Make sure to take your asthma medication as prescribed by your doctor.

  • If you have known allergies or triggers for your asthma, learn how to avoid them.

  • Monitor your symptoms. This allows you to track how well your asthma is being controlled.

  • Keep your doctor’s appointments, and don’t hesitate to talk to your doctor about any questions, concerns, or changes.

  • Stay healthy- eat well, exercise as directed by your doctor, don’t smoke, and wash your hands regularly.

Eosinophilic asthma had a poor prognosis in the past. However, as more doctors learn to recognize it and as treatments are being advanced, the outlook is changing. Work with your doctor to find a plan that keeps your asthma controlled and allows you to live a happy life.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2019 Apr 27

  1. Diagnosis and Management of Eosinophilic Asthma: a US Perspective. J Asthma Allergy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3990389/

  2. Choy DF, Hart KM, Borthwick LA, et al. TH2 and TH17 Inflammatory Pathways Are Reciprocally Regulated in Asthma. Sci Transl Med. 2015;7(301):301ra129.

  3. Eosinophilic Asthma. American Partnership for Eosinophilic Disorders. http://apfed.org/about-ead/eosinophilic-asthma/

  4. International ERS/ATS Guidelines on Definition, Evaluation and Treatment of Severe Asthma. American Thoracic Society. https://www.thoracic.org/statements/resources/allergy-asthma/severe-asthma-full.pdf

  5. Jantina C. de Groot, Anneke ten Brinke, Elisabeth H.D. Bel. Management of the Patient with Eosinophilic Asthma: A New Era Begins. ERJ Open Research. http://openres.ersjournals.com/content/1/1/00024-2015

  6. Green RH, Brightling CE, Bradding P. The Reclassification of Asthma Based on Subphenotypes. Curr Opin Allergy Clin Immunol. 2007 Feb;7(1):43-50. https://www.ncbi.nlm.nih.gov/pubmed/17218810

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