What do asthma and atopic dermatitis have in common?

Although they may appear to have nothing to do with it, both conditions belong to the group of type 2 inflammatory diseases, and so they often occur simultaneously in the same person without the latter establishing connections between them.

What do diseases like asthma, atopic dermatitis (also known as eczema), or a food allergy have in common? In addition to their high prevalence, they all belong to the group of type 2 inflammatory diseases, pathologies whose immune system-specific response can contribute to unpredictable, persistent or uncontrollable symptoms, reducing the patient’s quality of life, both physically and mentally.

On the occasion of the event The connection of type 2 inflammation: discovering hidden connections’, which Sanofi Genzyme and Regeneron organized last October within the framework of the European Respiratory Society congress, we interviewed Ian Pavord, a professor at Oxford University and a reference expert in respiratory medicine.

What is a type 2 inflammatory disease?

Type 2 inflammation is a normal immune system response. However, when hyperactive, it can play a key role in inflammatory diseases such as atopic dermatitis, asthma, nasal polyps, eosinophilic esophagitis, certain food and environmental allergies or respiratory disease exacerbated by aspirin. Additionally, people with a type 2 inflammatory disease are more likely to live with another type of pathology.

Is it known why this immune system response occurs? Is there a genetic factor involved?

Genetic factors may predispose people to an excess of type 2 inflammation, and other environmental triggers such as tissue damage may also play a role. Additionally, type 2 inflammation manifests in different ways depending on the affected person. 

Recent scientific studies have shown that excess type 2 inflammation underlies different atopic, allergic and inflammatory conditions. As the symptoms of these diseases are unpredictable and random, many will probably remain undiagnosed. How many people are estimated to have one or more of these conditions without being diagnosed?

Lack of awareness of these conditions means that people cannot fully understand their illness or diseases, how they are connected, and what treatment options are available to them.

It is difficult to know this fact precisely because, as I told you, many people live with several type 2 inflammatory pathologies. For example, up to 35% of people with severe asthma also have atopic dermatitis. About 50% of patients with chronic rhinosinusitis with nasal polyps (CSR) also have asthma and up to 43% of those with severe asthma also have CSR. Also, 17% of people with CSR have atopic dermatitis and 13% of people with moderate to severe atopic dermatitis have CSR.

75% of patients with moderate to severe atopic dermatitis have no control over the disease and 45% of patients with asthma in Europe who are being treated are also not controlled. About 79% of patients with CSR experience recurrent polyps one year after surgery.

 

What are the major challenges in the study of these diseases? Which lines of research are open and which are the most promising?

The biggest challenge is getting patients and doctors to understand that assessing type 2 inflammation is a key component in diagnosing certain diseases, such as asthma. For this pathology, for example, elevated biomarkers of type 2 inflammation are associated with the risk of asthma attacks and with the likelihood of inhaled corticosteroids and other treatments being successful.

There’s a recent work that shows, very consistently, that patients with elevated blood eosinophil counts and exhaled nitric oxide have a high risk of asthma attacks, regardless of the traditional measures we use to evaluate asthma control. It is now clear that controlling type 2 inflammation in the airways is an important additional target of asthma therapies.

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