Immunomodulating Approach to Asthma Using Mycobacteria

© Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology • The Korean Academy of Pediatric Allergy and Respiratory Disease http://e-aair.org Asthma is characterized by chronic inflammation of the airways, and inhaled steroids (ICSs) currently represent the most effective anti-asthma medication. However, due to the potential side-effects of long-term use of ICSs, the recurrence of asthma soon after the withdrawal of ICSs, and the refractoriness of airway remodeling to ICS treatment, other approaches for the control of asthma are needed. The current concept of asthma pathogenesis is that pathogenic immune responses to common respiratory exposure in vulnerable individuals result in persistent inflammation and aberrant repair processes in the airways. Therefore, early intervention during the developing stages of this intractable disease would present the best strategy for managing asthma. Moreover, cellular components, such as dendritic cells (DCs) active during the developing stage, continuously affect the chronic airway inflammation in asthma, even without further exposure to the relevant allergens. Thus, interventional approaches to modulate the early pathogenic immune response, such as allergen-specific immunotherapy, anti-IgE monoclonal antibody (omalizumab), probiotics, and Bacillus Calmette-Guérin (BCG) vaccination appear to work in preventing the development of asthma, and in treating established asthmatic disease. In 1997, Shirakawa et al. reported an inverse association between tuberculin skin responses and atopic disorder. Further epidemiologic studies revealed an association between tuberculosis or BCG vaccination and reduced prevalence of asthma or allergy. Because BCG is less virulent than Mycobacterium tuberculosis, the efficacy of the BCG vaccination in asthma prevention is lower than that of active tuberculosis, and only lasts for 2 years. As the article by Kim et al. published in this issue, many animal studies have demonstrated the preventive or therapeutic effects of BCG vaccination on asthma. In this context, we performed a double-blinded placebo-controlled human study in 2002, and demonstrated that BCG vaccination improved lung function and reduced medication-use in adult asthmatics. In subsequent studies, BCG revaccination further improved lung function, and the greatest benefit occurred in Immunomodulating Approach to Asthma Using Mycobacteria