Genomics and Metagenomics of Asthma Severity

Asthma is a chronic inflammatory disease of the airways characterized by reversible airflow obstruction and a bronchial hyperreactivity in response to a variety of stimuli. In most patients, the onset of asthma symptoms may be controlled. However, many of them may manifest asthma attacks or crises of breathing called exacerbations, which occur with breathing problems, wheezing, coughing or tightness of chest, and may threaten their life. Such exacerbations are caused by a combination of environmental and genetic factors. However, since studies so far have been limited, a reduced number of genes associated with the predisposition to these complications have been identified. In addition, some studies have used next-generation DNA sequencing techniques to characterize the microbiome (i.e., microbial community) of the airways, finding changes related to asthma. The main hypothesis of the Genomics and Metagenomics of Asthma Severity (GEMAS) study is that exacerbations of asthma are caused by a combination of the intrinsic genetic factors of the individual, changes in the respiratory microbiome and the interaction between both factors. The objectives of this project are: 1) to identify genetic variants that are associated with asthma exacerbations; 2) to examine the changes occurring in the microbial communities of the oral cavity and respiratory tract in individuals with exacerbations; 3) to analyze the association of the host genetic variants and the microbiome changes related to exacerbations. A total of 300 Spanish subjects with asthma with and without a history of asthma exacerbations in the past 12 months will be recruited. Saliva, nasal and pharyngeal samples will be collected to study the oral cavity and the upper respiratory tract microbiome through next-generation sequencing technologies. Sequencing of the 16S ribosomal RNA (16S rRNA) gene will allow to characterize the bacterial diversity and abundance, as well as to infer the functionality of the microbiome in each sample. These parameters will be used to establish correlations between the microbiome and the presence of asthma exacerbations. Finally, the association between the genetic variation associated with exacerbations in genomic studies and the measurements of abundance, diversity and functions related to exacerbations will be jointly examined.