Gut microbiome signature and nasal lavage inflammatory markers in young asthmatics

Background Asthma is a complex disease and a severe global public health problem resulting from interactions between genetic background and environmental exposures. It has been suggested that the gut microbiota may be related to asthma development, however, such relationships needs further investigation. Objective This study aimed to characterize the gut microbiota as well as the nasal lavage cytokine profile of asthmatic and non-asthmatic individuals. Methods Stool and nasal lavage samples were collected from 29 children and adolescents with Type 2-asthma (defined as asthma with >2.5% eosinophils in sputum, and a positive skin prick test) and 28 children without asthma in Brazil. Amplicon sequencing of the stool bacterial V4 region of the 16S rRNA gene was performed using Illumina MiSeq. Microbiota analysis was performed using QIIME2 and PICRUST. Type 2-asthma phenotype was characterized by high sputum eosinophil counts and positive skin prick tests for house dust mites, cockroaches, cat or dog dander. The nasal immune marker profile was assessed using a customized multiplex panel. Results The stool microbiota differed significantly between asthmatic and non-asthmatic participants (p=0.001). Bacteroides was more abundant in participants with asthma (p<0.05), while Prevotella was more abundant in non-asthmatics (p<0.05). In asthmatics, the relative abundance of Bacteroides correlated with IL-4 concentration in nasal lavage. Inference of microbiota functional capacity identified differential fatty acid biosynthesis in asthmatics compared to non-asthmatics. Conclusion The stool microbiota differed between asthmatics and non-asthmatics in young people in Brazil. Asthma was associated with higher Bacteroides which correlated with nasal IL-4 concentration.