Th1 inflammation and remodeling characterized by local tissue destruction coexist in pulmonary emphysema and other diseases. To test the hypothesis that IL-18 plays an important role in these responses, we characterized the regulation of IL-18 in lungs from cigarette smoke (CS) and room air-exposed mice and characterized the effects of CS in wild-type mice and mice with null mutations of IL-18Rα (IL-18Rα−/−). CS was a potent stimulator and activator of IL-18 and caspases 1 and 11. In addition, although CS caused inflammation and emphysema in wild-type mice, both of these responses were significantly decreased in IL-18Rα−/− animals. CS also induced epithelial apoptosis, activated effector caspases and stimulated proteases and chemokines via IL-18Rα-dependent pathways. Importantly, the levels of IL-18 and its targets, cathepsins S and B, were increased in pulmonary macrophages from smokers and patients with chronic obstructive lung disease. Elevated levels of circulating IL-18 were also seen in patients with chronic obstructive lung disease. These studies demonstrate that IL-18 and the IL-18 pathway are activated in CS-exposed mice and man. They also demonstrate, in a murine modeling system, that IL-18R signaling plays a critical role in the pathogenesis of CS-induced inflammation and emphysema.

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Asthma is a heterogeneous airway disease with various clinical phenotypes. It is crucial to clearly identify clinical phenotypes to achieve better asthma management.We used cluster analysis to classify the clinical groups of 724 asthmatic patients from the Cohort for Reality and Evolution of Adult Asthma in Korea (COREA), and in 1843 subjects from another independent Korean asthma cohort of Soonchunhyang University Asthma Genome Research Centre (SCH) (Bucheon, Republic of Korea). Hierarchical cluster analysis was performed by Ward's method, followed by k-means cluster analysis.Cluster analysis of the COREA cohort indicated four asthma subtypes: 1) smoking asthma; 2) severe obstructive asthma; 3) early-onset atopic asthma; and 4) late-onset mild asthma. An independent cluster analysis of the SCH cohort also indicated four clusters that were similar to the COREA clusters.Our results indicate that adult Korean asthma patients can be classified into four distinct clusters.

Bronchiectasis is a chronic respiratory disease characterised by abnormal dilatation of bronchi, which presents clinically with cough, sputum production and recurrent infection [1]. Although bronchiectasis had been regarded as an "orphan" disease [2], recent studies have shown that the prevalence of bronchiectasis is increasing and this disease causes a significant burden on public health, including increased healthcare costs, hospital admission and mortality [3][4][5].Data on the prevalence of bronchiectasis and bronchiectasis-related comorbidities are relevant, since comorbidities are important factors for predicting the risk of mortality in patients with bronchiectasis [6]. However, epidemiological data on the prevalence of bronchiectasis remain limited, especially in Asian populations. Furthermore, only a few studies have included a comprehensive evaluation of the prevalence of bronchiectasis-related comorbidities among Asians [1,7]. Thus, in the present study, the overall prevalence of bronchiectasis and associated comorbidities were investigated using a representative sample of national health insurance claims data in South Korea.To identify patients with bronchiectasis and investigate their comorbidities, data were used from the 2012-2017 Health Insurance Review and Assessment Service, National Patient Sample (HIRA-NPS), which is nationally representative and open to the public for research purposes [8]. The HIRA-NPS data are cross-sectional and composed of health insurance claim records during the year. The database includes approximately 1 400 000 individuals each year drawn by 3% stratified random sampling by age and sex from the entire population who had claims records during the year. It also provides information on healthcare costs, composed of payer's amounts and patient's out-of-pocket costs. South Korea has a government-run mandatory national health security system; 97% of the population is enrolled in the National Health Insurance and 3% in Medical Aid programmes [9].

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