Dual RNA-sequencing of macrophages infected with Mycobacterium avium reveals host-pathogen interaction in the context of clarithromycin treatment

Background: Mycobacterium avium is an opportunistic pathogen that requires complex multidrug treatment. Macrolides, like clarithromycin, are the cornerstone of treatment, but even macrolide-based treatment regimens have suboptimal outcomes. Combining transcriptomic profiling of macrophages and mycobacteria in an in vitro infection model may increase our understanding of the host-pathogen interaction and the effect of antibiotic treatment. Methods: To investigate the molecular interplay between pathogen and host, we developed an optimized protocol for dual RNA-sequencing of human monocyte-derived macrophages infected with M. avium. Results: Upon phagocytosis, host defense processes including immune activation and pathogen recognition were upregulated, while M. avium upregulated expression of PE/PPE genes, which are important for immune recognition. Clarithromycin did not affect gene regulation of the host; the effect of clarithromycin on M. avium gene expression was very different in RPMI compared to intracellular mycobacteria, likely due to the influence of the host environment on expression of the important regulatory WhiB genes. Conclusions These data identify the distinct stress responses of M. avium upon infection and clarithromycin treatment and underline the importance of taking the intracellular localization and interaction with the host into account when studying antibiotics against intracellular pathogens. Overall design: RNA-sequencing of M. avium within human monocyte-derived macrophages in the presence and absence of clarithromycin