The following is a summary of “Airway microbiota and immune mediator relationships differ in obesity and asthma,” published in the APRIL 2023 issue of Allergy & Immunology by Kozik, et al.

Asthma and obesity are complex conditions characterized by chronic inflammation and severe asthma related to obesity have been associated with differences in the microbiome. However, it was unclear whether there are differences in the airway microbiome and the relationship between microbiota and immune response in obese individuals with or without nonsevere asthma. Therefore, for a study, researchers sought to compare the airway microbiome and the relationship between microbiota and immune mediators between obese and nonobese individuals with and without mild to moderate asthma.

Cross-sectional analyses were conducted on the airway microbiome (induced sputum) and cytokine profiles from blood and sputum using 16S ribosomal RNA gene and internal transcribed spacer region sequencing to profile bacteria and fungi, as well as multiplex immunoassays. Analysis tools utilized in the study included QIIME 2, linear discriminant analysis effect size (LEfSe), Piphillin, and Sparse inverse covariance estimation for ecological association inference (SPIEC-EASI).

Regardless of asthma status, obesity was associated with significant differences in the structure and composition of the sputum bacterial community (assessed using unweighted UniFrac permutational analysis of variance, P = .02). These differences included a higher relative abundance of Prevotella, Gemella, and Streptococcus species. Among individuals with asthma, additional differences in the composition of sputum bacteria and fungal richness were observed between obese and nonobese individuals. 

In addition, correlation network analyses revealed differences in the relationships between cytokine mediators in obese and nonobese asthma, with the involvement of specific airway bacteria and markers such as blood PAI-1, sputum IL-1β, GM-CSF, IL-8, TNF-α, and several Prevotella species.

Obesity was associated with alterations in the sputum microbiome, and these differences are further pronounced in individuals with mild to moderate asthma. The distinct differences in the airway microbiota and the relationship between immune markers in obese asthma suggested the potential involvement of airway microbes that may impact the mechanisms or outcomes of asthma in individuals who are obese.

Source: jacionline.org/article/S0091-6749(22)02534-9/fulltext