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Asthma and obesity are both complex conditions characterized by chronic inflammation, and obesity-related severe asthma has been associated with differences in the microbiome. However, whether the airway microbiome and microbiota-immune response relationships differ between obese persons with or without non-severe asthma is unestablished.To compare the airway microbiome and microbiota-immune mediator relationships between obese and non-obese subjects, with and without mild-moderate asthma.We performed cross-sectional analyses of the airway (induced sputum) microbiome and cytokine profiles from blood and sputum, employing 16S rRNA gene and ITS region sequencing to profile bacteria and fungi, and multiplex immunoassays. Analysis tools included QIIME2, linear discriminant analysis effect size (LEfSe), Piphillin, and SParse InversE Covariance Estimation for Ecological Association Inference (SPIEC-EASI).Obesity, irrespective of asthma status, was associated with significant differences in sputum bacterial community structure and composition (unweighted Unifrac PERMANOVA, p=0.02), including a higher relative abundance of Prevotella, Gemella, and Streptococcus species. Among asthmatic subjects, additional differences in sputum bacterial composition and fungal richness were identified between obese and non-obese individuals. Correlation network analyses demonstrated differences between obese and non-obese asthma in relationships between cytokine mediators, and these together with specific airway bacteria, involving blood PAI-1, sputum IL1-β, GM-CSF, IL-8, TNF-α, and several Prevotella species.Obesity itself is associated with an altered sputum microbiome, which further differs in those with mild-moderate asthma. The distinct differences in airway microbiota and immune marker relationships in obese asthma suggest potential involvement of airway microbes that may impact mechanisms or outcomes of obese asthma. |
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