Abstract Number: PB1651
Meeting: ISTH 2020 Congress
Background: Lipopolysaccharides (LPSs), are well-known mediators of the inflammatory response. A plethora of groups have reported that LPSs potentiate platelet responses after weak stimulation. However, it has also been reported multiple times that LPSs do not affect platelet functioning.
Aims: Investigation of platelet functioning in the presence of LPSs and determination of the cause of the discrepancy in the previously published data.
Methods: Whole anticoagulated blood of healthy volunteers (12 persons, 18-25 years of age) within 3 hours of collection was used for all experiments. Platelet responses, activation of polymorphonuclear neutrophils (PMN) and platelet-PMN heteroaggregate formation were analysed by flow cytometry, light transmission aggregometry and western blotting. Thrombus growth and PMN activity were assessed by means of fluorescent microscopy in parallel-plate flow chambers with fibrillar collagen type I. LPSs from E.coli O111:B4 and O127:B8 at concentration 10 µg/ml (for experiments with PMNs) or 100 µg/ml (for whole blood experiments) were utilized in experiments.
Results: The activity of all utilized LPSs was confirmed by their ability to activate PMNs. 30-min incubation of LPSs with PMNs with PRP or washed platelets enhanced platelet-PMNs heteroaggregate formation without activation of platelets. LPSs also increased the amount of highly activated PMNs during thrombus formation and slightly increased PMNs crawling velocity. LPSs did not substantially affect either thrombus growth or platelet aggregation. 0.5-2 hours incubation of platelets or whole blood with LPSs did not affect platelet functional responses (integrin activation, granule release, calcium signalling, phosphatidylserine exposure) to activation with ADP, collagen-related peptide of TRAP. LPSs were capable of restoring platelet responses reduced by sub-threshold doses of ADP upon P2 receptor desensitisation.
Conclusions: LPSs effects on platelet activation are limited to their effects on PMNs and their capability to compensate ADP-induced desensitisation of platelets. The study was supported by the Russian Science Foundation grant 17-74-20045.
To cite this abstract in AMA style:Martyanov A, Maiorov A, Filkova A, Ryabukh A, Panteleev M, Sveshnikova A. The Effects of E.coli Lipopolysaccharides on Platelet Function Are Limited to Re-Sensitization [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/the-effects-of-e-coli-lipopolysaccharides-on-platelet-function-are-limited-to-re-sensitization/. Accessed September 29, 2023.
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