Thromb Haemost 2016; 116(06): 1111-1121
DOI: 10.1160/TH16-03-0206
Cellular Haemostasis and Platelets
Schattauer Publishers Schattauer

Human recombinant alkaline phosphatase inhibits ex vivo platelet activation in humans

Rahajeng N. Tunjungputri
1  Department of Internal Medicine, Radboud university medical center, Nijmegen, The Netherlands
2  Center for Tropical and Infectious Diseases (CENTRID), Faculty of Medicine Diponegoro University - Dr. Kariadi Hospital, Semarang, Indonesia
,
Esther Peters
3  Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
4  Department of Pharmacology and Toxicology, Radboud university medical center, Nijmegen, The Netherlands
,
Andre van der Ven
1  Department of Internal Medicine, Radboud university medical center, Nijmegen, The Netherlands
,
Philip G. de Groot
5  Department of Clinical Chemistry and Haematology, University Medical Centre, Utrecht, The Netherlands
,
Quirijn de Mast
1  Department of Internal Medicine, Radboud university medical center, Nijmegen, The Netherlands
5  Department of Clinical Chemistry and Haematology, University Medical Centre, Utrecht, The Netherlands
,
Peter Pickkers
3  Department of Intensive Care Medicine, Radboud university medical center, Nijmegen, The Netherlands
› Author Affiliations
Financial support: R. Tunjungputri is an awardee of the DIKTI-Neso Fellowship from the Ministry of Research, Technology and Higher Education, Indonesia, and Radboud university medical center, The Netherlands.
Further Information

Publication History

Received: 11 March 2016

Accepted after minor revision: 07 September 2016

Publication Date:
09 March 2018 (online)

Summary

Sepsis-associated acute kidney injury (AKI) is associated with high morbidity and mortality. Excessive platelet activation contributes to AKI through the formation of microthrombi and amplification of systemic inflammation. Two phase II trials demonstrated that bovine-intestinal alkaline phosphatase (AP) improved renal function in critically ill patients with sepsis-associated AKI. In this study, we characterised the platelet-inhibiting effects of a human recombinant AP. Whole blood and platelet-rich plasma (PRP) of healthy volunteers (n=6) was pre-treated ex vivo with recAP, whereafter platelet reactivity to ADP, collagen-related peptide (CRP-XL) and Pam3CSK4 was determined by flow cytometry. RecAP (40 U/ml) reduced the platelet reactivity to ADP (inhibition with a median of 47%, interquartile range 43–49%; p<0.001) and tended to reduce platelet reactivity to CRP-XL (9%, 2–25%; p=0.08) in whole blood. The platelet-inhibiting effects of recAP were more pronounced in PRP both for ADP- (64%, 54–68%; p=0.002) and CRP-XL-stimulated samples (60%, 46–71%; p=0.002). RecAP rapidly converted ADP into adenosine, whereas antagonism of the A2A adenosine receptor partially reversed the platelet inhibitory effects of recAP. Platelets of septic shock patients (n=5) showed a 31% (22–34%; p=0.03) more pronounced reactivity compared to healthy volunteers, and this was completely reversed by recAP treatment. In conclusion, we demonstrate that recAP inhibits ex vivo human platelet activation through dephosphorylation of ADP and formation of adenosine as its turnover product. RecAP is able to reverse the platelet hyperreactivity present in septic shock patients. These effects may contribute to the beneficial effects of recAP as a new therapeutic candidate for sepsis-associated AKI.