Prebiotics, probiotics and synbiotics for the management of respiratory disease

Respiratory diseases are among the leading causes of death worldwide. In 2008, chronic obstructive pulmonary disease (COPD), lung infections, and lung cancer together attributed to 9.5 million deaths worldwide (Gibson et al. 2013). In parallel, the increase in the prevalence of allergic diseases including asthma is becoming a major global health concern (Devereux 2006, Gibson et al. 2013). According to the classical “hygiene hypothesis,” this increase in prevalence of allergic diseases can be attributed at least in part to reduced microbial exposure in early life (Devereux 2006). There is an unmet need for novel respiratory allergies and airway disease prevention strategies (Prescott and Nowak-Wegrzyn 2011). In this regard, understanding the relationships between the microbial populations and microbial diversity and the host in health and disease has gained a lot of attention in the last 10 years (Charlson et al. 2012a, Erb-Downward et al. 2011, Madan et al. 2012). In the last 3 years, a new frontier in pulmonary research noted as “airway microbiome” has emerged (Huang 2013, Huang and Lynch 2011, Marsland et al. 2013). There is increasing evidence that the composition of the airway microbiome varies under healthy and diseased conditions (Huang and Lynch 2011). Studies in this research field revealed that the bacterial diversity is affected by the severity of the chronic respiratory disease (Blainey et al. 2012, Erb-Downward et al. 2011, Gollwitzer and Marsland 2014, Marri et al. 2013). However, it should be realized that it is not clear yet whether a change in microbiome is the chicken or the egg in relation to symptoms of respiratory disease. Interestingly, the concept of the airway microbiome also holds promise for lung transplantation research as lower microbiota diversity was found in the respiratory tract of transplant recipient (Charlson et al. 2012b).