Introduction
Dendritic cell (DC)-derived extracellular vesicles (EVs) are known to regulate host immunity, however, their role during bacterial pathogenesis remains unclear. We observed a critical Helicobacter pylori (Hp) virulence factor, the vacuolating cytotoxin A (VacA), specifically targets DC-EVs. Accumulating evidence suggests that VacA facilitates Hp persistence by limiting DC, T-cell and B-cell functions. How the toxin interacts with these cells in vivo remains poorly understood, but may be explained by DC-EVs disseminating VacA to distant immune centres and mediating specific cell interactions.
Aims
To characterise VacA’s influence on the physical properties of DC-EV and the impact of VacA+-EVs on immune cells functions.
Method
Murine DC cell line MutuDC and human primary DCs were assessed for VacA localisation by correlative light microscopy. Small EVs (sEVs) were isolated by ultracentrifugation for analysis by immunoblot, transmission electron microscopy, nanotracking and mass spectrometry, and evaluation of DC-EV-mediated delivery of VacA to recipient immune cells.
Results
VacA localised exclusively to EVs of MutuDC and human primary DCs. VacA localisation to DC-EVs was dependent on lipid raft. Moreover, VacA+-sEVs were enriched in key markers of immune cell functions and possessed the ability to deliver VacA to naïve immune cells. Analysis concerning the functional impacts of VacA+-sEVs is ongoing.
Conclusions
This study reveals that VacA specifically coats DC-EVs and alters DC-EV immune marker composition. We propose that VacA hijacks DC-EVs to facilitate its delivery to immune cells for dysregulation of immune signalling. Our findings highlight a previously unrecognised role of EVs in bacterial pathogenesis.