Expression Levels of Eosinophil Granule Protein mRNAs in Induced Sputum Reflect Airway Hyperresponsiveness and Airflow Limitation

Expression Levels of Eosinophil Granule Protein mRNAs in Induced Sputum Reflect Airway Hyperresponsiveness and Airflow Limitation

JAE-WOO JUNG,^1,2 HYE-RYUN KANG,^1,3 HYUN-SEUNG LEE,^1,3 HEUNG-WOO PARK,^1,3 SANG HEON CHO,^1,3 KYUNG-UP MIN^1,3 and SEONG-WOOK SOHN⁴

¹Institute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul, Korea
²Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea
³Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
⁴Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang, Korea

Eosinophils are regarded as the major effector cells that produce symptoms in allergic diseases. Activation of eosinophils induces extracellular release of a number of eosinophil granule proteins, including major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil peroxidase (EPO), and eosinophil-derived neurotoxin. The objective of this study was to evaluate the differences and significance of the sputum eosinophil% and expression levels of eosinophilic granule protein mRNAs in allergic airway disease. Induced sputum samples were obtained from non-smokers with 25 asthma, 54 eosinophilic bronchitis, 16 allergic rhinitis, and 19 healthy control subjects. The eosinophil granule protein mRNAs were measured with real time RT-PCR. There was no correlation between the sputum eosinophil% and the mRNA level of any of eosinophil granule proteins. However, the expression levels of MBP and ECP mRNAs were higher in subjects with each of the specified allergic diseases than those in control subjects (P < 0.05). Moreover, in the subjects with allergic sensitization, the expression levels of MBP and EPO mRNAs were significantly higher in those with airway hyperresponsiveness (13 subjects) than in those without airway hyperresponsiveness (32 subjects) (P = 0.004 and 0.010, respectively). In asthma patients, the FEV1% was negatively correlated with ECP mRNA levels (r = −0.510, P = 0.022), but showed no correlation with sputum eosinophil%. In conclusion, mRNA levels of eosinophil granule proteins, rather than sputum eosinophil%, may reflect airway hyperresponsiveness and airflow limitation. In practice, consideration for the eosinophil% as well as the eosinophil granule proteins levels in induced sputum is needed.

keywords —— Keywords: asthma; eosinophil granule; eosinophilic bronchitis; induced sputum; rhinitis

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Tohoku J. Exp. Med., 2014, 233, 49-56

Correspondence: Seong-Wook Sohn, M.D., Ph.D., Department of Internal Medicine, Dongguk University Ilsan Hospital, 814 Siksa-Dong, Ilsandong-Gu, Goyang 410-773, Korea.

e-mail: seongwook@gmail.com