Saliva-SP-D Is a Practical Marker to Identify the Peripheral Airway Inflammation

S U N D A Y 492 Saliva-SP-D Is a Practical Marker to Identify the Peripheral Airway Inflammation Hiroki Murai, MD, PhD, Shintaro Okazaki, MD, Hisako Hayashi, MD, PhD, Akiko Kawakita, MD, Motoko Yasutomi, MD, PhD, Yusei Ohshima, MD, PhD; University of Fukui, Yoshida-gun, Japan, University of Fukui, Fukui, Japan. RATIONALE: Forced oscillation technique (FOT) is a utilitarian tool to verify the localization of airway structural changes, i.e. airway remodeling by measuring airway resistance and reactance. However, the interpretation of children’s data obtained by FOT require cautions, since the airway resistance is relatively higher than that of adults and changes with age. Meanwhile, serum levels of surfactant protein D (SP-D) have been shown a biomarker of bronchial asthma. METHODS: 22 asthmatic children and 11 healthy controls were recruited to the study. After taking informed consent from guardians, airway resistance (R5 and R20) and reactance (X5) were measured by forced oscillation technique using Mostgraph 01. Blood and saliva were then collected from the patients, and levels of SP-D were evaluated by ELISA. The relationship between the SP-D levels and the airway resistance adjusted by age and height were assessed. RESULTS: The levels of serum SP-D were not correlated with that of saliva SP-D (p50.78, r50.02). Saliva SP-Dwas elevated during asthma attacks compared with stable status (p50.01). The R5-R20 value, which represented peripheral airway resistance showed a positive correlation with saliva SP-D levels (p50.0321, r50.4579), whereas the R20 corresponding to central airway resistance did not. CONCLUSIONS: Saliva SP-D may be a practical marker to identify the peripheral airway inflammation of bronchial asthma. Further studies will be needed to clarify the underlying mechanisms of SP-D secretion in asthmatic patients.