The Immunotherapeutic Role of Bacterial Lysates in a Mouse Model of Asthma

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Recurrent respiratory tract infections in young children, especially viral infections, are the major cause of acute asthmatic exacerbations and contribute to development of asthma. Bacterial extracts have been used to improve the immune defenses of the respiratory tract. However, seldom studies have examined the effect of bacterial lysates on childhood asthma. In this study, we examined whether bacterial lysates (OM-85) will improve symptoms of asthmatic mice via modulation of the immune response.

Asthmatic mice models were established with OVA challenge and treated with oral administration of Broncho-Vaxom (OM-85). Next, infiltrations of inflammatory cells including eosinophil and neutrophils were examined. Pulmonary tissues in asthmatic mice models were analyzed by hematoxylin and eosin (HE) staining. The levels of Th1/Th2-typed cytokines in bronchoalveolar lavage fluid (BALF) of asthmatic mice models were examined by enzyme-linked immunosorbent assay.

Compared to control group, we found significant reduction of airway wall thickness, luminal stenosis, and mucus plug formation in asthmatic mice models after oral administration of OM-85. The infiltrations of eosinophil were also significantly decreased in BALF in asthmatic mice models. Oral administration of OM-85 was shown to suppress Th2-type cytokine levels.

Our findings provide evidence that oral administration of OM-85 is capable of attenuating airway inflammation in asthmatic mice models. Oral administration of OM-85 may have a positive impact in terms of asthma severity.