PB0765 - Impaired platelet function caused by Vibrio cholera outer membrane vesicles

Monday, July 11, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Waltraud C. Schrottmaier, PhD

Postdoc
Medical University of Vienna
Vienna, Wien, Austria

Co-Author(s)

Anita Pirabe, MSc

PhD Student
Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna
Vienna, Wien, Austria
UR

Ulrike Resch

Postdoc
Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna
Vienna, Wien, Austria
JS

Jonas Santol

PhD Student
Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna
Vienna, Wien, Austria
SF

Sabine Frühwirth

Master student
Medical University of Vienna
Vienna, Wien, Austria
KA

Kyaw M. Aung

Postdoc
Umeå University
Umeå, Vasterbottens Lan, Sweden
MD

Mitesh Dongre

Postdoc
Umeå University
Umeå, Vasterbottens Lan, Sweden
AD

Astrid Digruber

PhD student
University of Veterinary Medicine Vienna
Vienna, Wien, Austria
BJ

Bernd Jilma

Specialist for Internal Medicine
department of Clinical Pharmacology
Vienna, Wien, Austria
AK

Alexander K. Kirschner

Associate professor
Medical University of Vienna
Vienna, Wien, Austria
ME

Monika Ehling-Schulz

Professor
University of Veterinary Medicine Vienna
Vienna, Wien, Austria
SW

Sun N. Wai

Professor
Umeå University
Umeå, Vasterbottens Lan, Sweden
MF

Mattias N. Forsell

Associate professor
Department of Clinical Microbiology, Umeå University, SWE
Umea, Vasterbottens Lan, Sweden
Alice Assinger, PhD

Associate professor
Medical University of Vienna
Vienna, Wien, Austria

Background: Haemorrhagic complications in cholera disease are associated with bacteraemia and increased mortality. Vibrio cholerae, the causative pathogen of cholera, sheds outer membrane vesicles (OMV) to modulate and evade host immunity. However, given the immune-sensing capacity of platelets, these OMV may also affect platelet function.

Aims: We aimed to investigate whether V. cholerae-derived OMV may modulate haemostatic/pro-thrombotic platelet function.

Methods: OMV were isolated in the late logarithmic growth phase. Effects of OMV on platelet function were analysed in vitro by pre-incubating platelets with OMV from V. cholerae before assessing platelet activation using flow cytometry, light transmission aggregometry and Western Blot in response to various agonists. Platelet spreading and cytoskeletal remodelling were assessed by (super-resolution) fluorescence microscopy. In vivo relevance was tested in a model of FeCl3-induced thrombosis using mice transfused with OMV-treated platelets. To clarify species specificity OMV effects on platelet degranulation and GPIIb/IIIa activation was compared to OMV from different bacteria via flow cytometry.

Results: V. cholerae-derived OMV significantly reduced platelet degranulation (measured by surface P-selectin) and almost abolished GPIIb/IIIa activation independently of the agonist. Investigation of intracellular signalling events revealed profound impairment of AKT phosphorylation, whereas phosphorylation of p38 and vasodilator-stimulated phosphoprotein (VASP) were unaffected. OMV also diminished platelet aggregation and curtailed platelet spreading, which involved aberrant rearrangement of the actin cytoskeleton. In vivo, mice transfused with OMV-treated platelets were protected from FeCl3-induced thrombosis. Similar effects of OMV on platelet CD62P exposure and GPIIb/IIIa activation were also observed for other Vibrio strains.

Conclusion(s): Our results show that OMV from V. cholerae strongly impair pro-thrombotic platelet function in vitro and in vivo, mediated by inhibition of the central signalling hub AKT and dysregulation of the actin cytoskeleton. Thereby, OMV-mediated platelet inhibition may represent an underlying mechanism that contributes to haemorrhagic complications in cholera patients.