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Airway inflammation contributes to airway obstruction and airflow limitation by swelling the bronchial muscles. This causes the symptoms of asthma, such as wheeze, cough, breathlessness and chest tightness.1
Research has shown that up to 84% of asthma patients have Type 2 airway inflammation, which is particularly associated with exacerbations.2
Type 2 inflammation is mainly driven by interleukins IL-4, IL-5 and IL-13. These cytokines are involved in the recruitment and production of immunoglobulin E (IgE), eosinophils and nitric oxide (NO), which is then released in exhaled breath as FeNO (fractional exhaled nitric oxide).3
Recently, biomarkers have been increasingly used to measure airway inflammation. A biomarker (or biological marker) is a parameter that can be objectively measured and evaluated. It is an indicator of normal or pathogenic processes or pharmacologic response to treatment.4 The most common biomarkers in medicine include body temperature, blood pressure and HbA1c (marker of blood sugar).
FeNO correlates directly with the level of inflammation present in the lungs.5 FeNO testing is simple, immediate and non-invasive. It is the most convenient way to assess airway inflammation, right at the point-of-care.
1. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. 2021 update. 2. Heaney LG et al. Eosinophilic and noneosinophilic asthma: an expert consensus framework to characterize phenotypes in a global real-life severe asthma cohort. Chest. 2021;160(3):814-30. 3. Munakata M. Exhaled nitric oxide (FeNO) as a non-invasive marker of airway inflammation. Allergol Int. 2012;61(3):365-72. 4. Biomarkers Definitions Working Group.Biomarkers and surrogate endpoints: preferred definitions and conceptual framework. Clin Pharmacol Ther. 2001;69(3):89-95. 5. Wagener AH et al. External validation of blood eosinophils, FE(NO) and serum periostin as surrogates for sputum eosinophils in asthma. Thorax. 2015;70(2):115-20.