• Satoshi Konno, Natsuko Taniguchi, Hironi Makita, Yuji Nakamaru, Kaoruko Shimizu, Noriharu Shijubo, Satoshi Fuke, Kimihiro Takeyabu, Mitsuru Oguri, Hirokazu Kimura, Yukiko Maeda, Masaru Suzuki, Katsura Nagai, Yoichi M Ito, Sally E Wenzel, Masaharu Nishimura, and Hi-CARAT Investigators.
• 1 First Department of Medicine, and.
• Ann Am Thorac Soc. 2015 Dec 1; 12 (12): 1771-80.

RationaleSmoking may have multifactorial effects on asthma phenotypes, particularly in severe asthma. Cluster analysis has been applied to explore novel phenotypes, which are not based on any a priori hypotheses.ObjectivesTo explore novel severe asthma phenotypes by cluster analysis when including cigarette smokers.MethodsWe recruited a total of 127 subjects with severe asthma, including 59 current or ex-smokers, from our university hospital and its 29 affiliated hospitals/pulmonary clinics. Twelve clinical variables obtained during a 2-day hospital stay were used for cluster analysis. After clustering using clinical variables, the sputum levels of 14 molecules were measured to biologically characterize the clinical clusters.Measurements And Main ResultsFive clinical clusters were identified, including two characterized by high pack-year exposure to cigarette smoking and low FEV1/FVC. There were marked differences between the two clusters of cigarette smokers. One had high levels of circulating eosinophils, high IgE levels, and a high sinus disease score. The other was characterized by low levels of the same parameters. Sputum analysis revealed increased levels of IL-5 in the former cluster and increased levels of IL-6 and osteopontin in the latter. The other three clusters were similar to those previously reported: young onset/atopic, nonsmoker/less eosinophilic, and female/obese. Key clinical variables were confirmed to be stable and consistent 1 year later.ConclusionsThis study reveals two distinct phenotypes of severe asthma in current and former cigarette smokers with potentially different biological pathways contributing to fixed airflow limitation. Clinical trial registered with www.umin.ac.jp (000003254).

22 keywords...

hide…