Klebsiella Pneumoniae-Derived Outer Membrane Vesicles Impair Endothelial Function by inhibiting SIRT1

Background The potential role of Klebsiella pneumoniae (K.pn) in hypertension development has been emphasized, although the specific mechanisms have not been well understood. Outer membrane vesicles (OMVs) released by gram-negative bacteria modulate host cell functions through delivery of bacterial moleculars to host cells. Endothelial dysfunction is an important early event in the pathogenesis of hypertension, yet the impact of K.pn-secreted OMVs (K.pn OMVs) on endothelial function remains unclear. This study aims to investigate the effects of K.pn OMVs on endothelial function and uncover the underlying mechanisms. Methods K.pn OMVs were purified from the bacterial culture medium using ultracentrifugation and characterized by transmission electron microscopy nanoparticle tracking analysis, and OMV marker expression. Endothelium-dependent relaxation was measure using wire myograph following in vivo or ex vivo treatment with K.pn OMVs. The superoxide anion production was measured by confocal microscopy and HUVECs senescence was assessed according to SA-β-gal activity. SIRT1 ovexpression or activator was utilized to investigate the underlying mechanisms. Results Our data showed that K.pn markedly impaired acetylcholine-induced endothelium-dependent relaxation, and elevated superoxide anion production in endothelial cells in vivo. Similarly, in vivo and ex vivo studies showed that K.pn OMVs caused significant endothelial dysfunction, provoked endothelial and enhanced blood pressure. Further examination revealed that K.pn OMVs reduced the levels of SIRT1 and p-eNOS, along with an increase in the levels of NOX2, COX-2, ET-1 and p53 in endothelial cells. Notably, overexpression or activation of SIRT1 attenuated the adverse effects and protein changes caused by K.pn OMVs on endothelial cells Conclusion This study reveals a novel role of K.pn OMVs in endothelial dysfunction and dissects the relevant mechanism involved in this process, which will help to establish a comprehensive understanding of K.pn OMVs in endothelial dysfunction and hypertension from a new scope.