Clinical update on the use of biomarkers of airway inflammation in the management of asthma

Abstract

Biological markers are already used in the diagnosis and treatment of cardiovascular disease and cancer. Biomarkers have great potential use in the clinic as a noninvasive means to make more accurate diagnoses, monitor disease progression, and create personalized treatment regimes. Asthma is a heterogeneous disease with several different phenotypes, generally triggered by multiple gene-environment interactions. Pulmonary function tests are most often used objectively to confirm the diagnosis. However, airflow obstruction can be variable and thus missed using spirometry. Furthermore, lung function measurements may not reflect the precise underlying pathological processes responsible for different phenotypes. Inhaled corticosteroids and β₂-agonists have been the mainstay of asthma therapy for over 30 years, but the heterogeneity of the disease means not all asthmatics respond to the same treatment. High costs and undesired side effects of drugs also drive the need for better targeted treatment of asthma. Biomarkers have the potential to indicate an individual’s disease phenotype and thereby guide clinicians in their decisions regarding treatment. This review focuses on biomarkers of airway inflammation which may help us to identify, monitor, and guide treatment of asthmatics. We discuss biomarkers obtained from multiple physiological sources, including sputum, exhaled gases, exhaled breath condensate, serum, and urine. We discuss the inherent limitations and benefits of using biomarkers in a heterogeneous disease such as asthma. We also discuss how we may modify our study designs to improve the identification and potential use of potential biomarkers in asthma.

Keywords:

• asthma
• inflammation
• airway biomarkers
• urinary biomarkers
• serum biomarkers

Acknowledgments

The authors wish to thank Dr M Elliott and A Samra for their assistance and advice regarding tissue histology. We also thank the iCAPTURE biobank and the International Institute for the Advancement of Medicine for human tissue.

Disclosure

Supported by operating grants from the Canadian Institutes of Health Research, the Canadian/British Columbia Lung Associations, National Sanatorium Association, and Allergen, NCE and personal support awards from the Michael Smith Foundation for Health Research (D.R.D.) and the Canadian Institutes of Health Research (D.R.D.), D.D.S is holder of a Canadian Research Chair.