Haemophilin-Producing Strains of Haemophilus haemolyticus Protect Respiratory Epithelia from NTHi Colonisation and Internalisation

Nontypeable Haemophilus influenzae (NTHi) is a significant respiratory tract pathogen responsible for infections that collectively pose substantial health and socioeconomic burden. The clinical course of these largely dictated by NTHi interactions with host epithelia, thus, approaches disrupt colonisation invasion may have therapeutic potential. Survival, successful host–cell interactions, pathogenesis are reliant on NTHi’s ability to sequester host-derived haem. Previously, we demonstrated the potential exploiting this haem-dependence using closely related competitor bacterium, haemolyticus (Hh). Hh strains capable producing novel haem-binding protein haemophilin (Hpl) possessed potent inhibitory activity restricting access haem in broth co-culture environment. Here, extend work cell culture models more represent human epithelium show high levels hpl expression protect epithelial line monolayers against adhesion NTHi. Inhibitory was dependent level Hpl production, which stimulated challenge nasopharyngeal exposure. Provided protective benefits translate vivo applications, Hpl-producing probiotic utility inhibiting requisite colonisation.