Background: Although respiratory viral infections cause acute exacerbations of asthma, the inflammatory responses vary depending on the causative virus. The purpose of this study was to compare the inflammatory responses in the airways of acute exacerbations of asthma induced by respiratory syncytial virus (RSV) and influenza A virus. Methods: Sputum induction was performed in asthmatic patients with acute exacerbations induced by RSV (n = 6), influenza A (n = 7), and non-upper respiratory infection (URI)-related factors (n = 8). Sputum concentrations of cysteinyl leukotrienes (cysLTs), TNF-α and IFN-γ were measured. Results: Sputum cysLTs were significantly higher in RSV-induced exacerbations than in influenza A- and non-URI-induced exacerbations. Sputum TNF-α was significantly higher in influenza A-induced exacerbations than in RSV- and non-URI-induced exacerbations. Sputum IFN-γ was significantly lower in RSV-induced exacerbations than in the others. Conclusions: RSV and influenza A cause acute exacerbations and have different effects on airway inflammation in asthmatic patients. RSV significantly increased cysLTs, while influenza A significantly increased TNF-α in the airway. The underlying mechanism in virus-induced asthma might depend on the viral species.

Background: Respiratory syncytial virus (RSV) can infect myeloid dendritic cells

We showed that there are potentially a number of cases with COPD that are undiagnosed by general physicians in Japan. Measuring airflow limitation by spirometry in smokers with coexisting diseases, such as hypertension and chronic hepatitis, may be very beneficial because COPD is thought to be a systemic disease. The distribution of spirometers to general clinics is definitely needed to detect undiagnosed COPD.

The present findings suggest that RSV infection increases the number of DCs and the cysLT concentrations in lung tissues of asthma patients, both of which could result in enhanced allergic airway inflammation.

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