The airway microbiome in asthma

Asthma is a heterogenous airways disease characterized by variable airflow limitation, airway inflammation and bronchial hyperresponsiveness. There is evidence to suggest that the airway microbiome plays an important role in asthma pathophysiology. Most microbiome studies have investigated the bacterial constituents of the microbiome and further studies are needed to investigate the role of the airway virome and mycobiome in asthma.

Airway microbiome dysbiosis is associated with asthma development, disease severity and inflammatory endotypes. However, it remains unclear whether dysbiosis drives inflammation or is a result of inflammation. Haemophilus and Moraxella alongside rhinovirus and respiratory syncytial virus have been shown to be associated with the development of asthma in children. In established asthma, airway microbiome dysbiosis is associated with severity and risk of exacerbation. Distinct airway microbiome profiles are observed for the different inflammatory endotypes. Asthmatic patients with eosinophilic inflammation have higher microbial diversity similar to healthy individuals while neutrophilic inflammation is associated with reduced microbial diversity, higher bacterial load and a pathogen-dominated microbiome profile suggesting an important role for dysbiosis in asthma that is currently refractory to anti-T2 biologic therapy.

To understand the role of the microbiome in asthma, microbiome data must be integrated with other 'omic approaches' such as proteomics. Recent studies have used a multi-omic approach to investigate the microbiome and host interaction as well as identifying asthma endotypes and potential therapeutic targets. Antibiotics, probiotics, monoclonal antibodies, and diet could theoretically be used to therapeutically target the airway and gut microbiome in asthma.