Exhaled Breath Temperature and Systemic Biomarkers for Assessment of Airway Inflammation in Asthmatics

Abstract

OBJECTIVES: Asthma is characterised by chronic airway inflammation and remodelling. Inflammation may alter the thermal balance of the affected tissues secondary to changes in the blood flow. Measurement of exhaled breath temperature (EBT) is a simple, safe and non-invasive technique to detect airway inflammation. The objective of this study was to measure EBT in asthma patients and compare it with healthy controls and also to correlate it with serum biomarkers of inflammation and remodelling. METHODS: 24 male asthma patients and 23 age and gender matched healthy controls were recruited in the study. EBT and core body temperature were recorded followed by spirometry to measure forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and peak expiratory flow rate (PEFR). Serum levels of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were quantified by ELISA. RESULTS: Asthmatics had significantly lower FEV1% predicted compared to healthy subjects. EBT in asthma patients was significantly higher as compared to healthy controls while rate of rise of EBT was not significantly different. Serum biomarker of inflammation i.e. IL-6 and of tissue remodelling i.e. VEGF, MMP-9 and TIMP-1 were significantly raised in asthma patients while the ratio of MMP-9/TIMP-1 was comparable between two groups. But no correlation was observed between EBT and serum biomarkers. CONCLUSION: EBT may be used as an adjunct tool for non-invasive assessment of airway inflammation and remodelling in asthma patients. © Journal of the Association of Physicians of India 2011.