Platelet activation determines the severity of thrombocytopenia in dengue infection

Amrita Ojha, Dipika Nandi, Harish Batra, Rashi Singhal, Gowtham K. Annarapu, et al.

Scientific Reports. 2017 January 31. DOI: 10.1038/srep41697

Speaker: Tan Sia Seng (陳聲昇)                                   Time: 15:00-16:00, Mar. 29, 2017

Commentator: Chia-Yi Yu, Ph.D. (余佳益老師)          Place: Room 601

Abstract:

        Thrombocytopenia is a common finding in dengue patients and has been associated with bleeding in affected subjects resulting from either mild or severe dengue virus (DENV) infection. In health subjects, platelet counts between 150,000 and 450,000 platelets per μl, while in dengue patients, the platelet counts may reach as low as < 40,000 platelets per μl during fever days¹. Development of thrombocytopenia in dengue patients mainly rests on two events: decreased production of platelets in bone marrow and increased destruction and clearance of platelets². To investigate the possible mechanism of thrombocytopenia in DENV infections, the authors described a direct correlation between activation and depletion of platelets in these patients. Their results showed that the levels of platelet activation markers, such as P-selectin, PAC-1, Phosphatidylserine (PS), platelet-derived microparticle (MP) are increased during low platelet count period, especially on day 4 of fever. Platelet count recovery was observed on day 10, together with the decreased of platelet activation markers. In low platelet count period, high copies of DENV genome are detected in those activated platelets, along with C3 complement and IgG binding. Furthermore, the authors showed that the activated platelet increased by DENV infection via dosage-dependent method. Thus, large numbers of DENV-activated platelets were phagocytosed by monocytes. The clearance of DENV-activated platelet was prohibited in the presence of platelet activation inhibitor, prostacyclin. Altogether, the status of platelet activation is a key determinant of thrombocytopenia in dengue infection.

References

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