Single-cell RNA-sequencing of circulating eosinophils from asthma patients reveals an inflammatory signature.

Asthma is the most common chronic lung disorder in the United States. While asthma is heterogeneous, blood eosinophils are central to the pathogenesis in most cases. Yet, the power of modern omics has not been widely applied to the study of asthma eosinophils. We report single cell RNA sequencing of blood eosinophils obtained from patients with severe asthma, mild asthma, and healthy volunteers. The eosinophils from asthma patients showed marked heterogeneity in the population and, as with healthy controls, clustered into 3 subsets suggesting at least 3 gene expression states circulating in the blood. Eosinophils from asthma patients had an inflammatory gene signature with enrichment of interferon α and γ pathways. Moreover, a greater fraction of these eosinophils expressed CCR3, the chemokine receptor that mediates trafficking to inflamed tissues and activates eosinophils. Our data support implementation of larger studies to define the transcriptional drivers of asthma.