Past, present and future of macrolide therapy for chronic rhinosinusitis in Japan

In 1984, the effectiveness of low-dose, long-term erythromycin treatment (macrolide therapy) for diffuse panbronchiolitis (DPB) was first reported in Japan. The 5-year survival rate for DPB improved from 62.9 to 91.4% after implementation of macrolide therapy. The usefulness of this treatment has since been demonstrated in patients with other chronic airway diseases, such as chronic bronchitis, cystic fibrosis, bronchiectasis, bronchial asthma, and chronic rhinosinusitis (CRS). The new 14-membered macrolides clarithromycin and roxithromycin and the 15-membered macrolide azithromycin are also effective for treating these inflammatory diseases. The mechanism of action of the 14- and 15-membered macrolides may involve anti-inflammatory rather than anti-bacterial activities. Macrolide therapy is now widely used for the treatment of CRS in Japan; it is particularly effective for treating neutrophil-associated CRS and is useful for suppressing mucus hypersecretion. However, macrolide therapy is not effective for eosinophil-predominant CRS, which is characterized by serum and tissue eosinophilia, high serum IgE levels, multiple polyposis, and bronchial asthma. Recent reports have described the clinical efficacy of macrolides in treating other inflammatory diseases and new biological activities (e.g., anti-viral). New macrolide derivatives exhibiting anti-inflammatory but not anti-bacterial activity thus have therapeutic potential as immunomodulatory drugs. The history, current state, and future perspectives of macrolide therapy for treating CRS in Japan will be discussed in this review.