The Effect of Probiotic Lactic Acid Bacteria (LAB) Strains on the Platelet Activation: A Flow Cytometry-Based Study

Abstract

Platelet-activation and agonist-induced platelet aggregation process to the pathogenesis of Infective Endocarditis (IE), bacteremia symptoms or other thrombotic complications and cardiovascular diseases. Activation of platelets by probiotic lactic acid bacteria strains is considered as thrombotic initiative factor contributing to the development and progression of Lactobacillus endocarditis. The main purpose of the current study was to evaluate the immunologic enhancement effect of probiotic strains L. plantarum, L. acidophilus and L. rhamnosus on the activation of blood platelets. Whole fresh blood flow cytometry was used to measure p-selectin expression and fibrinogen binding at basal levels and following stimulation with platelet agonists and probiotic lactic acid bacteria strains. Platelet activation was determined by labelling with FITC-conjugated anti-human fibrinogen and phycoerythrin (PE)- conjugated anti-human CD62p before analysis by flow cytometry. Thrombin Receptor Activator Peptide-6 (TRAP-6) was used as positive control. The percentage of CD62p-positive platelets, FITC-conjugated and the light scatter profiles of the agonist-activated platelets were used to identify the occurrence and degree of platelet activation. Probiotic lactic acid bacteria strains included in this study did not show any effect on spontaneous activation of human blood platelets. These test strains also failed to exacerbate or diminish the platelet activation property when co-incubated with TRAP-6 platelet agonist. Hence, this is the first in vitro report showing the safety of a group of probiotic lactic acid bacteria in terms of their potential to contribute to the pathogenesis of infective endocarditic (IE), bacteremia symptoms or other thrombotic disorders and correlated cardiovascular complications by initiating the platelet activation.