CC BY 4.0 · TH Open 2022; 06(03): e156-e167
DOI: 10.1055/a-1827-7365
Original Article

Platelet Toll-Like-Receptor-2 and -4 Mediate Different Immune-Related Responses to Bacterial Ligands

Marius Niklaus
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Philipp Klingler
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Katja Weber
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Angela Koessler
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Sabine Kuhn
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Markus Boeck
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
Anna Kobsar
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
,
1   Institute of Clinical Transfusion Medicine and Haemotherapy, University of Wuerzburg, Wuerzburg, Germany
› Institutsangaben

Abstract

Background Like immune cells, platelets express toll-like receptors (TLRs) on their surface membrane. TLR2 and TLR4 are able to recognize bacterial antigens and have the potential to influence hemostatic functions and classical intracellular signaling pathways. This study investigated the role of TLR2 and TLR4 for immune-related functions in human platelets.

Materials and Methods Washed platelets and neutrophils were prepared from fresh human peripheral blood. Basal-, Pam3CSK4- (as TLR2 agonist) and Lipopolysaccharides (LPS; as TLR4 agonist) -induced CD62P expression, fibrinogen binding and TLR2 or TLR4 expression, intracellular reactive oxygen species (ROS) production in H2DCFDA-loaded platelets and uptake of fluorescence-labeled TLR ligands, and fluorophore-conjugated fibrinogen were evaluated by flow cytometry. Analysis of platelet–neutrophil complexes was performed after coincubation of washed platelets and neutrophils in the presence and absence of TLR2 or TLR4 agonists on poly-L-lysine coated surfaces, followed by immunostaining and immunofluorescence imaging.

Results Pam3CSK4 rapidly and transiently increased TLR2 and TLR4 expression. Over the course of 30 minutes after activation with Pam3CSK4 and LPS, the expression of both receptors decreased. Pam3CSK4-stimulated intracellular ROS production and the uptake of TLR ligands or fibrinogen much stronger than LPS. Besides, TLR4 activation led to a significant increase of platelet–neutrophil contacts.

Conclusion Stimulation leads to rapid mobilization of TLR2 or TLR4 to the platelet surface, presumably followed by receptor internalization along with bound TLR ligands. After activation, platelet TLR2 and TLR4 mediate different immune-related reactions. In particular, TLR2 induces intracellular responses in platelets, whereas TLR4 initiates interactions with other immune cells such as neutrophils.

Supplementary Material



Publikationsverlauf

Eingereicht: 21. Januar 2022

Angenommen: 08. April 2022

Accepted Manuscript online:
18. April 2022

Artikel online veröffentlicht:
11. Juli 2022

© 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/)

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany