The clinical role of host and bacterial-derived extracellular vesicles in pneumonia

[Display omitted] •EVs are secreted by host cells and pathogens during infection.•Host EVs exert direct and cell-mediated antiviral and antibacterial effects.•EVs secreted during infection promote inflammation via immunogenic cargo molecules.•EVs are promising candidates for novel vaccines, biomarkers and therapeutics. Pneumonia is among the leading causes of morbidity and mortality worldwide. Due to constant evolution of respiratory bacteria and viruses, development of drug resistance and emerging pathogens, it constitutes a considerable health care threat. To enable development of novel strategies to control pneumonia, a better understanding of the complex mechanisms of interaction between host cells and infecting pathogens is vital. Here, we review the roles of host cell and bacterial-derived extracellular vesicles (EVs) in these interactions. We discuss clinical and experimental as well as pathogen-overarching and pathogen-specific evidence for common viral and bacterial elicitors of community- and hospital-acquired pneumonia. Finally, we highlight the potential of EVs for improved management of pneumonia patients and discuss the translational steps to be taken before they can be safely exploited as novel vaccines, biomarkers, or therapeutics in clinical practice.