Host-specific bacterial modulation of airway gene expression and alternative splicing.

The human microbiome varies extensively between individuals. While there are numerous studies investigating the effects of inter-individual differences on microbiome composition, there are few studies investigating inter-individual effects on microbial modulation of the host, or host-specific effects. To address this knowledge gap, we colonized human bronchial epithelial air-liquid interface tissue cultures generated from six different adults with one of three phylogenetically diverse bacteria and compared how each microbe differentially modulated host gene expression in each of the six donors. Microbial treatment had the strongest effect on transcription, followed by donor-specific effects. Gene pathways differed markedly in their donor- and microbe-specificity; interferon expression was highly donor-dependent while transcription of epithelial barrier and antibacterial innate immunity genes were predominantly microbially driven. Moreover, we evaluated whether microbial regulation of alternative splicing was modulated by donor. Strikingly, we found significant non-redundant, donor-specific regulation of alternative splicing exclusively in the Gram-positive commensal microbes. These findings highlight that microbial effects on the human airway epithelium are not only species-specific but also deeply individualized, scoring the importance of host context in shaping microbe-induced transcriptional and splicing responses.