p38MAPK is involved in apoptosis development in apheresis platelet concentrates after riboflavin and ultraviolet light treatment.
BACKGROUND
Pathogen inactivation (PI) accelerates the platelet (PLT) storage lesion, including apoptotic-like changes. Proteomic studies have shown that phosphorylation levels of several kinases increase in PLTs after riboflavin and UV light (RF-PI) treatment. Inhibition of p38MAPK improved in vitro PLT quality, but the biochemical basis of this kinase's contribution to PLT damage requires further analysis.


METHODS
In a pool-and-split design, apheresis PLT concentrates were either treated or kept untreated with or without selected kinase inhibitors. Samples were analyzed throughout 7 days of storage, monitoring in vitro quality variables including phosphatidylserine exposure, degranulation, and glucose metabolism. Changes in the protein expression of Bax, Bak, and Bcl-xL and the activities of caspase-3 and -9 were determined by immunoblot analysis and flow cytometry, respectively.


RESULTS
The expression levels of the proapoptotic proteins Bax and Bak, but not the antiapoptotic protein Bcl-xL, were significantly increased after the RF-PI treatment. This trend was reversed in the presence of p38MAPK inhibitor SB203580. As a result of increasing proapoptotic protein levels, caspase-3 and -9 activities were significantly increased in RF-PI treatment during storage compared with control (p < 0.05). Similarly, p38MAPK inhibition significantly reduced these caspase activities compared with vehicle control after RF-PI treatment (p < 0.05).


CONCLUSIONS
These findings revealed that p38MAPK is involved in signaling leading to apoptosis triggered by RF-PI. Elucidation of the biochemical processes influenced by PI is a necessary step in the development of strategies to improve the PLT quality and ameliorate the negative effects of PI treatment.
Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.
Zhongming
Z
Chen
Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.|Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
Peter
P
Schubert
Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.
Brankica
B
Culibrk
Canadian Blood Services, Vancouver, British Columbia, Canada.|Centre for Blood Research, University of British Columbia, Vancouver, British Columbia, Canada.|Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
Dana V
DV
Devine
D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects*; D051017:Apoptosis Regulatory Proteins / Q000097:blood; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects*; D053148:Caspase 3 / Q000097:blood; D053453:Caspase 9 / Q000097:blood; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D017319:Photosensitizing Agents / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000097:blood; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011725:Pyridines / Q000494:pharmacology; D012256:Riboflavin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D000099190:MAP-Kinase-Activated Kinase 2
D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D053453:Caspase 9; D007093:Imidazoles; D047908:Intracellular Signaling Peptides and Proteins; D017319:Photosensitizing Agents; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011725:Pyridines; D012256:Riboflavin; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C505407:CASP3 protein, human; C506433:CASP9 protein, human; C093642:SB 203580