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How Do Eosinophils Cause Asthma

Causes Of Eosinophilic Asthma

What is Eosinophilic Asthma?

Eosinophilic asthma is a form of asthma associated with high levels of a white blood cell called eosinophils. More than twenty-five million people in the United States of America have different types of asthma, and fifteen percent of the people have severe asthma that is difficult to control with standard medications. The symptoms include shortness of breath, wheezing, tightness in the chest, coughing, obstructed airflow, stuffy nose, chronic sinus infections, anosmia, a lost sense of smell, and a runny nose.

Eosinophilic asthma is considered a leading cause of severe asthma, affecting up to sixty percent of people with the severe form of the disease. In the population as a whole, eosinophilic asthma is rare, affecting only five percent of adults with asthma. It has some common symptoms with the other types of asthma including suffering from inflamed airways, blocked by fluid and mucus, and experiencing spasms that make it difficult to breathe.

Unlike other kinds of asthma, eosinophilic asthma involves abnormally high levels of a particular type of white blood cells called eosinophils, which make up a part of the immune system and help the body fight off infection. Eosinophils help control inflammation in reaction to foreign invaders in the body, which plays a beneficial role in isolating and controlling a disease site.

Here are some risk factors associated with Eosinophilic Asthma.

How To Treat Eosinophilic Asthma

Depending on the condition your doctor may recommend certain type of drugs to manage the condition and help you breathe easily. The most common Eosinophilic Asthma treatment includes:

  • Corticosteroids
  • Leukotriene modifiers
  • Biologic therapies

Corticosteroids: These can be recommended by your doctor to take them orally or inhale them however, pills have more side effects than an inhaler so use it carefully.

Leukotriene Modifiers: Leukotriene is already present in your body that combines with eosinophils and acts as a major cause for inflammation. The leukotriene modifiers inhibits the inflammatory response caused in the body.

Biologic Therapies: These therapies are provided to the patient to block the chemicals in the body that is responsible for the inflammation and swelling. These are provided by intravenous drip or injection.

When Is Quick Relief For Asthma Not Enough


  • Take your quick relief inhaler more than TWO TIMES A WEEK?
  • Awaken at night with asthma more than TWO TIMES A MONTH?
  • Do you refill you quick relief inhaler more than TWO TIMES A YEAR?
  • Use prednisone TWO or more times a year for flares of asthma?
  • Measure changes in peak flow with asthma symptoms of more than TWO TIMES 10 ?

If you answer YES to any of the questions, current guidelines suggest you talk with your physician about adding an inhaled anti-inflammatory to improve your asthma control.

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Types Of Severe Asthma

There are two main categories of severe asthma Type-2 inflammation and Non-Type-2 inflammation. These categories are based on a persons response to treatment. Type-2 inflammation includes allergic asthma and eosinophilic asthma and Non-Type-2 inflammation includes non-eosinophilic asthma. For example, allergic asthma and e-asthma respond to treatment with inhaled corticosteroids and IgE -directed therapy or other biologics listed in the above table. Patients with Non-Type-2 inflammation, including non-eosinophilic asthma, generally do not respond well to inhaled corticosteroids. Allergic asthma and e-asthma have distinct biomarkers and treatment options available today. Treatments for non-eosinophilic asthma are currently being development.

Allergic asthma is caused by exposure to allergens such as pollen, pet dander, molds, etc. Most people diagnosed with allergic asthma will also have a diagnosis of hay fever or rhinitis. For these patients, exposure to allergens causes the bodys immune system to produce immunoglobulin E, an antibody that attaches to certain cells and causes them to release chemicals creating an allergic reaction. When this happens, common symptoms are sneezing, itchy/watery eyes, severe allergic reactions , and increased airway sensitivity.

Non-eosinophilic asthma includes neutrophilic, smooth-muscle mediated and mixed cells. People in this subgroup have few to no eosinophils in test results, and do not respond well to inhaled corticosteroids.

Role Of Innate Immune Activation

What are eosinophils, and what role do they play in asthma ...

The common pathophysiological features of non-eosinophilic asthma involve an IL-8 mediated neutrophil influx and the subsequent neutrophil activation is a potent stimulus to increased airway hyperresponsiveness. Although the stimuli that trigger this response are diverse , the common features are consistent with activation of innate immune mechanisms rather than IgE mediated activation of acquired immunity. Recent data indicate a role for Toll-like receptors and CD14 in this process. TLRs can recognise a large variety of chemically diverse stimuli which then trigger proinflammatory responses involving NF-κB activation and chemokine production characteristic of non-eosinophilic asthma .

There is also the potential for combined activation of both innate and allergen specific inflammatory mechanisms to occur in asthma. This could result in a mixed eosinophil/neutrophil response as has been observed in some cases of acute asthma, and may explain the ability of ozone and NO2 to potentiate allergen induced asthmatic responses.

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How Is It Diagnosed

If youve been diagnosed with asthma but dont seem to respond well to treatment, your doctor may suspect you have a less common subtype of asthma. Theyll likely evaluate your condition and look for additional signs or symptoms that can direct them toward a diagnosis.

In the case of EA, the easiest step is to check your levels of white blood cells. For this, your doctor will collect blood, sputum, or saliva and send it to a lab. High levels of eosinophils can affirm your doctors suspected diagnosis.

In addition to the blood test, however, your doctor may conduct a physical exam. Certain physical symptoms, such as nasal polyps, can confirm the suspected diagnosis. The combination of the blood test and the physical exam may be enough for your doctor to diagnose you.

1 in 12 people has asthma. As doctors now recognize that asthma is more than one condition, they realize that the subtypes need specific treatments. Individual treatments for each subtype can help you achieve the best outcome for the condition.

Traditional asthma treatment involves inhaled corticosteroids and a rescue inhaler. However, people with EA dont always respond well to inhaled corticosteroids. Higher doses may lose their impact too, requiring a switch to an entirely new treatment.

The most common treatments for EA include the following.

Symptoms Of Eosinophilic Asthma

A person who has EA typically has more severe asthma symptoms of coughing, wheezing, shortness of breath, and tightness in the chest. If you have attacks that land you in the hospital, it is possible that this is a symptom of EA.

Other symptoms of EA are obstructed airflow due to inflammation and mucus. Think things like a stuffy nose and nasal drainage. Chronic sinus infections and nasal polyps are also symptoms.

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Eosinophilic Inflammation Responds Well To Corticosteroids

This is because corticosteroids work to reduce eosinophil levels. I don’t want to get into how this happens . I just want you to now corticosteroids suppress the effects of eosinophils.

Systemic steroids help reverse asthma attacks and inhaled corticosteroids help prevent asthma attacks or make them less severe when they do occur. They suppress eosinophils and reduce their numbers. They prevent them from doing their job, which is causing aggressive airway inflammation.

This is why inhaled corticosteroids are now considered top-line medicines for helping allergic asthmatics obtain good asthma control.6

The Role Of The Eosinophil In Health

Linda Rogers, ATS 2018 Treatment of severe eosinophilic asthma with IL-5 antagonists

In comparison to the roles that eosinophils play in diseases and infections, relatively little is known about their purpose in health. However, an increasing number of homeostatic mechanisms have been attributed toor at least associated witheosinophils in recent years. This has prompted a call for a fundamental change of the perception of eosinophils purely as cytotoxic effector cells .

In health, eosinophils are found in the thymus, spleen, lymph nodes, and gastrointestinal tract . The number of eosinophils in the thymus declines with age . Eosinophils may have a role in T cell selection. In a mouse model of MHC I-restricted acute negative selection, eosinophil recruitment to the corticomedullary region of the thymus and association with apoptotic bodies has been demonstrated . Eosinophils also enhance the ability of macrophages to phagocytose apoptotic thymic cells .

Eosinophils migrate to the GI tract during embryonic development, i.e., prior to the development of any viable gut flora . In health, they are present throughout the GI tractwith the notable exception of the esophagus. Eosinophils contribute to the immune defense against gut microorganisms, due to multiple antimicrobial properties. Other potential homeostatic roles for eosinophils within the gut are not currently well defined but may relate to their ability to interact with the enteric neuronal system and increase smooth muscle reactivity .

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What Is Eosinophilic Asthma Treatment

For many years, healthcare providers considered asthma as a distinct diagnosis a blanket diagnosis for inflammation of the airways and difficulty breathing. Healthcare providers now realize that there are various subtypes of asthma eosinophilic asthma is one such subtype.

Eosinophilic asthma, also called EA, is a subtype of asthma that is characterized by elevated levels of white blood cells.

This specific subtype is quite rare unfortunately, it is severe, difficult to treat and presents in adulthood.

So, how does EA differ from classic asthma? In the case of classic asthma, asthma symptoms are typically triggered by an allergen, such as dust or mold. This allergen causes inflammation of the airways, which causes wheezing and difficulty breathing. Though there are various degrees of severity, this type of asthma can be treated using conventional treatment modalities, such as corticosteroid inhalers.

In the case of EA, it typically presents in adulthood and is rarely caused by allergies. It causes swelling of the airways of the lungs, and the initial symptom is typically shortness of breath as such, it may not appear as if the diagnosis is asthma because wheezing may not be present.

Those with EA have increased numbers of eosinophils in the blood, lung tissue and mucus that is coughed up from the lungs. Research indicates that having elevated eosinophils may correlate with an increased risk of developing EA in the future.

Symptoms of EA include:

Eosinophilic Asthma Blood Test

The number of eosinophils in a patients blood are measured. The blood draw is a simple, minimally-invasive procedure. It may be performed in a doctors office. People with eosinophilic asthma will have a high eosinophil count . High eosinophils with asthma does not always mean that a person has eosinophilic asthma. Other types of eosinophil-associated disease can cause too many eosinophils in the blood as well. Therefore, a doctor will interpret the results in context with a patients history, symptoms, and clinical exam.

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What Is The Role Of Ige In Severe Asthma

The importance of B lymphocytes to present antigens for antibody production is well documented and IgE fixed to the membrane through CD23 molecules increases their capacity to capture allergens, amplifying the allergic response . In addition, some very interesting data have suggested that omalizumab may modulate human B-cell functions, including IgE synthesis .

The histopathological hallmark of BA consists in the constant presence, even in mild and intermittent forms of the disease, at the level of the bronchial mucosa of epithelial lesions, thickening of basement membrane, and inflammatory infiltration by activated eosinophils . It has been shown that human blood eosinophils express all chains of the FcRI receptor and can be influenced by IgE antibodies . Despite being fully saturated by IgE, the real function of this receptor on human eosinophils remains incompletely defined . However, a direct effect of IgE on eosinophils is supported by the demonstration that omalizumab induces the apoptosis of these cells . Table summarises the effects of IgE on eosinophil function .

Table 1 Direct effects of IgE on eosinophil functions

How Is Asthma Prevented And Treated

What are eosinophils, and what role do they play in asthma ...

There is no cure for asthma. Control symptoms by taking asthma medicines and avoiding your triggers. With proper treatment and an asthma management plan, you can reduce your symptoms and enjoy a better quality of life.

Talk to your health care provider about your asthma symptoms and be sure to discuss any changes in your asthma management or status.

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Role Of The Pharmacist

Pharmacists play a critical role in the selection of treatment for EA, as well as the education and assessment of patients with EA. Although the benefits and risks of biologic therapy for EA must be carefully weighed, other patient factors must also be carefully considered, such as affordability, access, and preference. Pharmacists should also assess adherence to ICS treatment and rule out other causes of asthma exacerbation prior to adjunctive treatment recommendations for severe EA. In addition, pharmacists can assist patients with referrals to support services as well as psychological services to manage emotional, social, and other burdens of EA and its management.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

What Can I Do To Lower The Eosinophil Count In The Blood

If there is a mild transient eosinophilia with no symptom, no action is necessary. The count probably will return to normal in the following test.

On the other hand is there is a moderate or severe eosinophilia you should visit your doctor and ask about the medication you are taking. Several drugs may raise the eosinophil count.

If there is an underlying cause, for example a parasitic infestation it is necessary to treat and solve previously this disease.

Corticosteroids reduce the eosinophils in the blood. If your doctor considers it appropriate he may prescribe them to you.

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What Are The Complications Associated With An Eosinophil Count

An eosinophil count uses a standard blood draw, which you have likely had many times in your life.

As with any blood test, there are minimal risks of experiencing minor bruising at the needle site. In rare cases, the vein may become swollen after blood is drawn. This is called phlebitis. You can treat this condition by applying a warm compress several times each day. If this isnt effective, you should consult your doctor.

Excessive bleeding could be a problem if you have a bleeding disorder or you take blood-thinning medication, such as warfarin or aspirin. This requires immediate medical attention.

A Brief Introduction To Eosinophilic Asthma And Non

Dupilumab in Asthma with Elevated Eosinophils – Interview with Sally Wenzel

Asthma is a chronic lung disease. It manifests as the inability to breathe. You wheeze when you encounter different triggers. Historically, doctors thought there was one type of asthma. Therefore, all asthma treatment was essentially the same.

Scientists and Doctors now agree on two main types of asthma: Eosinophilic and Non Eosinophilic Asthma .

Each of them have similar symptoms that people with asthma are familiar with, those being wheezing, coughing, shortness of breath, etc. The interesting part is HOW those symptoms manifest in the body. In other words, the root cause of why you have asthma. EA and NEA both start not in the lungs like previously thought, but in the immune system.

Understanding the type of asthma you have can help you and your doctor understand what type of medicine would work best for you, giving you greater control over your asthma.

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How To Treat Severe Asthma

Once your asthma specialist has determined the type of severe asthma you are suffering from, they can tailor treatment based on your specific type. Basic treatment for severe persistent asthma consists of inhaled corticosteroids. Additional long-term controller medicines, such as long-acting beta 2 agonists , montelukast or theophylline, are added if asthma is still uncontrolled. Oral corticosteroids can be added on to treatment if patients are still experiencing symptoms and flare-ups.

A personalized treatment plan may include:

Macrolide AntibioticsMacrolide antibiotics are used to help the body fight infection. These medicines control the number of white blood cells found in your airways. One study showed positive results using macrolide antibiotics in people with high counts of neutrophils in blood or sputum samples. Doctors dont suggest these medications be used long term though because side effects, such as antibiotic resistance, can be very serious.

What Are The Most Common Symptoms

An increase in the numbers of eosinophils is typical of atopic asthma. Symptoms of atopic asthma are:

  • Wheezing which sounds like whistling when breathing
  • Breathlessness
  • A tight chest like a band tightening around it

A severe asthma attack may cause the following symptoms:

  • Severe and constant wheezing, coughing and chest tightness
  • Breathlessness so severe that you are unable to speak, eat or sleep
  • Fast heartbeat
  • Drowsiness, confusion, exhaustion or dizziness
  • Fainting

Common symptoms of a parasitic infection are:

  • Diarrhoea

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The Discovery Of Ige And Its Role In Allergic Inflammation

While the discovery of IgE in 1966 brought to an end the search for the elusive reagin, it unlocked an era of discovery that investigated the genetics, structure, functions and clinical applications of this immunoglobulin . As has been recognised since the early part of the twentieth century, IgE has unique properties among the immunoglobulin isotypes in its abilities both to induce extremely rapid pathological responses and to act as a highly sensitive immunological amplifier. Furthermore, it is well established that IgE levels are increased in patients affected by atopic conditions and that IgE provides the critical link between the antigen recognition role of the adaptive immune system and the effector functions of mast cells and basophils at mucosal and cutaneous sites of environmental exposure . These functions have made IgE an attractive target for pharmacological intervention with IgE blockade having clinical potential across many different therapy areas.


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