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Restored response to ADP downstream of purinergic P2Y 12 receptor in apheresis platelets after pathogen‐reducing xenon flash treatment
Author(s) -
Abe Hideki,
Abe Takaaki,
Shiba Masayuki,
Satake Masahiro
Publication year - 2018
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/trf.14578
Subject(s) - phosphorylation , platelet , chemistry , purinergic receptor , adenosine diphosphate , receptor , adenosine triphosphate , p2y receptor , biochemistry , biology , immunology , platelet aggregation
BACKGROUND Our previous study revealed that pathogen‐reducing filtered xenon flash‐treated platelets (fXe‐PLTs) showed sustained aggregation in response to adenosine diphosphate (ADP), but apheresis‐collected PLTs (Aph‐PLTs) showed reversible aggregation. STUDY DESIGN AND METHODS Aph‐PLTs, fXe‐PLTs, and freshly prepared PLTs (PRP‐PLTs) from whole blood were used to investigate the following responses to ADP: concentration response and effects of ADP receptor antagonists on aggregation, the cytosolic calcium (Ca 2+ ) flux downstream of P2Y 1 receptor signaling, and phosphorylation of vasodilator‐stimulated phosphoprotein (VASP) and signaling intermediate protein Akt downstream of the P2Y 12 receptor. RESULTS The aggregation of Aph‐PLTs by ADP (10 µM) changed from reversible to sustained in an fXe flash dose‐dependent manner. The concentration‐response curve of Aph‐PLTs showed a fivefold higher 50% effective concentration compared with PRP‐PLTs, and fXe treatment decreased it to threefold. While the basal Ca 2+ level was higher both in Aph‐ and fXe‐PLTs than in PRP‐PLTs, the increase of cytosolic Ca 2+ by ADP remained unchanged in Aph‐ and PRP‐PLTs, but was slightly reduced in fXe‐PLTs. Although the forskolin‐induced VASP phosphorylation was significantly reduced in Aph‐PLTs, and partially restored by the fXe treatment, ADP stimulation attenuated this phosphorylation to an equivalent extent among the three PLT types. The ADP‐stimulated time‐dependent Akt phosphorylation was weak in Aph‐PLTs, whereas fXe‐PLTs and PRP‐PLTs showed a marked increase. CONCLUSION These results indicate that the reversible aggregation of Aph‐PLTs is the consequence of insufficient Akt phosphorylation. The fXe treatment restores the increase of phosphorylated Akt, resulting in the sustained aggregation of fXe‐PLTs similar to those of PRP‐PLTs.