A diagnosis of asthma in children, in particular babies, toddlers, and preschool-aged children, can be difficult. Many of the symptoms of asthma are also common symptoms of other illnesses that occur in early childhood. Spirometry as a means of assessment is also not a suitable test for children in this age group. As a consequence, the only way to diagnose asthma in young children is through frequent assessment.1 Biomarkers in asthma represent an opportunity to elicit early intervention in young children with asthma-like symptoms and differentiate children with asthma earlier.
Induced sputum and urine samples have both been suggested as potential sources for biomarkers in asthma. One of the most important aspects of identifying a biomarker is, of course, that it can be identified in a noninvasive way. Here, we will discuss the merits of each in relation to diagnosing asthma in children specifically.
Exercise-induced bronchoconstriction is a hallmark feature of asthma. Using exercise-induced bronchoconstriction as a trigger, Gharib et al.2 looked for proteomic changes in subject airways in induced sputum (Thermo Scientific). The induced sputum proteome was selectively enriched in proteins mapping to specific functional roles, presenting a noteworthy opportunity to search for biomarkers in asthma. Shotgun proteomics analysis (Thermo Scientific) identified a number of proteins, clearly distinguishing between asthma patients and healthy controls. Induced sputum proved to be powerful in identifying biomarkers in asthma and a means for detection that could potentially be applied to young children.
The bioavailability of urine lends it as a worthy source for examination of biomarkers, in particular biomarkers in asthma. Mattarucchi et al.3 were able to demonstrate that there are changes to metabolites, discriminating asthmatics from nonasthmatics. There may be some potential down the road to characterize asthma using these methods or even identify metabolites that play a central role in the underlying airway inflammation.
Although obtaining urine is a far simpler method for obtaining samples for proteomic analysis in young children, its distance from the source is perhaps a disadvantage. Some successful and potentially useful results were produced using induced sputum. Although collection methods are more time consuming and may require more patience in this younger age group, they could have real potential in the near future for biomarkers in asthma.
1. Asthma Foundation, http://www.asthmafoundation.org.au/Child_Diagnosis.aspx
2. Gharib, S.A., et al. (2011) ‘Induced sputum proteome in healthy subjects and asthmatic patients‘, Journal of Allergy and Clinical Immunology, 128 (6), (pp. 1176-1184)
3. Mattarucchi, E., Baraldi, E., and Guillou, C. (2012) ‘Metabolomics applied to urine samples in childhood asthma; differentiation between asthma phenotypes and identification of relevant metabolites‘, Biomedical Chromatography, 26 (1), (pp. 89-94).