Mild to moderate asthma – mechanisms and phenotyping

2024: ERS satellite online

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DELA MED SIG

Sammanfattning: Astma är en sjukdom där lungfunktionen varierar över tid och mellan individer, mellan normalt och kraftigt nedsatt. Vissa symtom kan hävas med luftförsvidgande medel och andra kräver långvarig antiinflammatorisk behandling, men en del förändringar är mer eller mindre irreversibla. Kunskap och ett aktivt handläggande av underliggande inflammation och hypersekretion är avgörande för att förhindra exacerbationer och försämring i sjukdom.

What do I need to know about mild and moderate asthma? 

Hot topics of asthma in a clinical context were covered by Professor Celeste Porsbjerg (Copenhagen, Denmark) in a presentation titled What do I need to know about the mechanisms and phenotyping of mild to moderate asthma? This presentation included practical advise to clinicians working with asthma.

Reversibility of asthma manifestations may vary

Asthma patients are diverse, not only in disease severities, but also in underlying mechanisms driving the disease. Asthma is known for causing variable airflow obstruction, reversible in nature, but not all factors contributing to the manifestation of the disease display the same reversibility¹. Understanding the patient’s specificities is key to effectively find the most suitable treatment.

Immune hyperresponsiveness of airway epithelium

The airway epithelium was described as having a key role in the asthma pathology. In addition to the barrier function, the epithelium can be considered the origin of the immune hyperresponsiveness seen in asthmatic patients. The inflammatory response and induced inflammation are the result of exposure to an otherwise harmless agent. The inflammatory response could lead to asthma exacerbations, highlighting the interest in the airway epithelium.^1,2 The structural changes that drive airway remodelling and airway hypersecretion are derived from airway epithelium.

Understanding hyperresponsiveness type

Airway remodelling and airway hypersecretion are two components of asthma that might not be fully reversible with treatment, and airway hypersecretion could potentially accelerate loss of lung function^1,2. Immune hyperresponsiveness and airway hyperresponsiveness are two different things, and Professor Porsbjerg highlighted the importance of differentiating between them. Some patients never experience exacerbations while exacerbations among other patients are the predominant feature of their disease. 

Blood versus sputum eosinophils

The most widely used biomarkers for assessing T2 inflammation are blood eosinophils and FeNO. Nevertheless, sputum eosinophils is the golden standard method but does not necessarily correlate with blood eosinophil counts. Normal blood eosinophil values are seen in 1 out of 3 patients with elevated sputum eosinophils. Therefore, blood eosinophils may be a poor measure for inflammation. Induced sputum analysis, as well as adherence to treatment, should be considered and evaluated, respectively. ³

Allergies and asthma control 

A final reminder regarding allergies: Besides evaluating if T2 inflammation is present, clinicians could potentially help a great number of asthma patients by also considering the probability of concurrent allergy. Uncontrolled allergic rhinitis causes poor asthma control and treating allergic rhinitis adequately improves asthma control. In the same manner, allergen immunotherapy is shown to reduce the need for asthma treatment and can also prevent progression of asthma.⁴

ID 7374-18.03.2024