TY - JOUR A1 - Koessler, Juergen A1 - Klingler, Philipp A1 - Niklaus, Marius A1 - Weber, Katja A1 - Koessler, Angela A1 - Boeck, Markus A1 - Kobsar, Anna T1 - The Impact of Cold Storage on Adenosine Diphosphate-Mediated Platelet Responsiveness JF - TH Open N2 - Introduction  Cold storage of platelets is considered to contribute to lower risk of bacterial growth and to more efficient hemostatic capacity. For the optimization of storage strategies, it is required to further elucidate the influence of refrigeration on platelet integrity. This study focused on adenosine diphosphate (ADP)-related platelet responsiveness. Materials and Methods  Platelets were prepared from apheresis-derived platelet concentrates or from peripheral whole blood, stored either at room temperature or at 4°C. ADP-induced aggregation was tested with light transmission. Activation markers, purinergic receptor expression, and P2Y12 receptor function were determined by flow cytometry. P2Y1 and P2X1 function was assessed by fluorescence assays, cyclic nucleotide concentrations by immunoassays, and vasodilator-stimulated phosphoprotein (VASP)-phosphorylation levels by Western blot analysis. Results  In contrast to room temperature, ADP-induced aggregation was maintained under cold storage for 6 days, associated with elevated activation markers like fibrinogen binding or CD62P expression. Purinergic receptor expression was not essentially different, whereas P2Y1 function deteriorated rapidly at cold storage, but not P2Y12 activity. Inhibitory pathways of cold-stored platelets were characterized by reduced responses to nitric oxide and prostaglandin E1. Refrigeration of citrated whole blood also led to the attenuation of induced inhibition of platelet aggregation, detectable within 24 hours. Conclusion  ADP responsiveness is preserved under cold storage for 6 days due to stable P2Y12 activity and concomitant disintegration of inhibitory pathways enabling a higher reactivity of stored platelets. The ideal storage time at cold temperature for the highest hemostatic effect of platelets should be evaluated in further studies. KW - platelet physiology KW - cold storage KW - adenosine diphosphate KW - purinergic receptors KW - inhibitory signaling Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229387 VL - 4 IS - 3 ER - TY - JOUR A1 - Kobsar, Anna A1 - Koehnlechner, Karina A1 - Klingler, Philipp A1 - Niklaus, Marius A1 - Zeller-Hahn, Julia A1 - Koessler, Angela A1 - Weber, Katja A1 - Boeck, Markus A1 - Koessler, Juergen T1 - The effect of short-term refrigeration on platelet responsiveness JF - Scientific Reports N2 - Storage of platelet concentrates (PC) at cold temperature (CT) is discussed as an alternative to the current standard of storage at room temperature (RT). Recently, we could show that cold-induced attenuation of inhibitory signaling is an important mechanism promoting platelet reactivity. For developing strategies in blood banking, it is required to elucidate the time-dependent onset of facilitated platelet activation. Thus, freshly prepared platelet-rich-plasma (PRP) was stored for 1 and 2 h at CT (2–6 °C) or at RT (20–24 °C), followed by subsequent comparative analysis. Compared to RT, basal and induced vasodilator-stimulated phosphoprotein (VASP) phosphorylation levels were decreased under CT within 1 h by approximately 20%, determined by Western blot analysis and flow cytometry. Concomitantly, ADP- and collagen-induced threshold aggregation values were enhanced by up to 30–40%. Furthermore, platelet-covered areas on collagen-coated slides and aggregate formation under flow conditions were increased after storage at CT, in addition to induced activation markers. In conclusion, a time period of 1–2 h for refrigeration is sufficient to induce an attenuation of inhibitory signaling, accompanied with an enhancement of platelet responsiveness. Short-term refrigeration may be considered as a rational approach to obtain PC with higher functional reactivity for the treatment of hemorrhage. KW - short‑term refrigeration KW - platelet responsiveness KW - cold temperature Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301390 VL - 12 IS - 1 ER - TY - JOUR A1 - Schossee, Nadine A1 - Veit, Gabriele A1 - Gittel, Julia A1 - Viebahn, Johannes A1 - Niklaus, Marius A1 - Klingler, Philipp A1 - Üçeyler, Nurcan A1 - Klinker, Erdwine A1 - Kobsar, Anna A1 - Boeck, Markus A1 - Koessler, Juergen T1 - Profile of the single-use, multiple-pass protein A adsorber column in immunoadsorption JF - Vox Sanguinis N2 - Background and Objectives Immunoadsorptions (IA) are used to remove autoantibodies from the plasma in autoimmune disorders. In this study, we evaluated the effects of a single-use, recombinant staphylococcal protein A-based immunoadsorber on blood composition of the patient. Materials and Methods In a cohort of patients with myasthenia gravis or stiff-person syndrome, essential parameters of blood cell count, coagulation, clinical chemistry or plasma proteins and immunoglobulins (Ig) were measured before and after IA (n = 11). Results In average, IA reduced the levels of total IgG, IgG1, IgG2 and IgG4 by approximately 60%, the acetylcholine receptor autoantibody levels by more than 70%. IgG3, IgA or IgM were diminished to a lower extent. In contrast to fibrinogen or other coagulation factors, the column markedly removed vitamin K-dependent coagulation factors II, VII, IX and X by approximately 40%–70%. Accordingly, international normalized ratio and activated partial thromboplastin time were increased after IA by 59.1% and 32.7%, respectively. Coagulation tests almost returned to baseline values within 24 h. Blood cell count, electrolytes, total protein or albumin were not essentially affected. No clinical events occurred. Conclusion The single-use, multiple-pass protein A adsorber column is highly efficient to remove IgG1, IgG2 and IgG4 or specific acetylcholine receptor autoantibodies from the plasma. Coagulation parameters should be monitored, since the column has the capacity to largely reduce vitamin K-dependent factors. KW - plasma KW - apheresis technologies KW - apheresis-therapeutic KW - blood processing KW - haemostasis Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259689 VL - 117 IS - 3 ER - TY - JOUR A1 - Niklaus, Marius A1 - Klingler, Philipp A1 - Weber, Katja A1 - Koessler, Angela A1 - Kuhn, Sabine A1 - Boeck, Markus A1 - Kobsar, Anna A1 - Koessler, Juergen T1 - Platelet Toll-Like-Receptor-2 and -4 Mediate Different Immune-Related Responses to Bacterial Ligands JF - TH Open N2 - 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. KW - receptors KW - immunity KW - cell-cell interactions KW - platelet physiology Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301401 VL - 6 IS - 3 SP - e156 EP - e167 ER -