Dual RNASeq Reveals NTHi-Macrophage Transcriptomic Changes During Intracellular Persistence

• Published in: Frontiers in cellular and infection microbiology Vol. 11; p. 723481
• Main Authors: Ackland, Jodie, Heinson, Ashley I., Cleary, David W., Christodoulides, Myron, Wilkinson, Tom M. A., Staples, Karl J.
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 23-08-2021
• Subjects: Cellular and Infection Microbiology; dual RNAseq; host-pathogen interactions; intracellular persistence; macrophage; NTHi
• ISSN: 2235-2988; 2235-2988
• DOI: 10.3389/fcimb.2021.723481

Nontypeable
Haemophilus influenzae
(NTHi) is a pathobiont which chronically colonises the airway of individuals with chronic respiratory disease and is associated with poor clinical outcomes. It is unclear how NTHi persists in the airway, however accumulating evidence suggests that NTHi can invade and persist within macrophages. To better understand the mechanisms of NTHi persistence within macrophages, we developed an
in vitro
model of NTHi intracellular persistence using human monocyte-derived macrophages (MDM). Dual RNA Sequencing was used to assess MDM and NTHi transcriptomic regulation occurring simultaneously during NTHi persistence. Analysis of the macrophage response to NTHi identified temporally regulated transcriptomic profiles, with a specific ‘core’ profile displaying conserved expression of genes across time points. Gene list enrichment analysis identified enrichment of immune responses in the core gene set, with KEGG pathway analysis revealing specific enrichment of intracellular immune response pathways. NTHi persistence was facilitated by modulation of bacterial metabolic, stress response and ribosome pathways. Levels of NTHi genes
bioC
,
mepM
and
dps
were differentially expressed by intracellular NTHi compared to planktonic NTHi, indicating that the transcriptomic adaption was distinct between the two different NTHi lifestyles. Overall, this study provides crucial insights into the transcriptomic adaptations facilitating NTHi persistence within macrophages. Targeting these reported pathways with novel therapeutics to reduce NTHi burden in the airway could be an effective treatment strategy given the current antimicrobial resistance crisis and lack of NTHi vaccines.