Platelet proteome reveals novel pathways of platelet activation and platelet-mediated immunoregulation in dengue

Abstract

Dengue is the most prevalent human arbovirus disease worldwide. Dengue virus (DENV) infection causes syndromes varying from self-limiting febrile illness to severe dengue. Although dengue pathophysiology is not completely understood, it is widely accepted that increased inflammation plays important roles in dengue pathogenesis. Platelets are blood cells classically known as effectors of hemostasis which have been increasingly recognized to have major immune and inflammatory activities. Nevertheless, the phenotype and effector functions of platelets in dengue pathogenesis are not completely understood. Here we used quantitative proteomics to investigate the protein content of platelets in clinical samples from patients with dengue compared to platelets from healthy donors. Our assays revealed a set of 252 differentially abundant proteins. In silico analyses associated these proteins with key molecular events including platelet activation and inflammatory responses, and with events not previously attributed to platelets during dengue infection including antigen processing and presentation, proteasome activity, and expression of histones. From these results, we conducted functional assays using samples from a larger cohort of patients and demonstrated evidence for platelet activation indicated by P-selectin (CD62P) translocation and secretion of granule-stored chemokines by platelets. In addition, we found evidence that DENV infection triggers HLA class I synthesis and surface expression by a mechanism depending on functional proteasome activity. Furthermore, we demonstrate that cell-free histone H2A released during dengue infection binds to platelets, increasing platelet activation. These findings are consistent with functional importance of HLA class I, proteasome subunits, and histones that we found exclusively in proteome analysis of platelets in samples from dengue patients. Our study provides the first in-depth characterization of the platelet proteome in dengue, and sheds light on new mechanisms of platelet activation and platelet-mediated immune and inflammatory responses.

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome

“…For example, it is now known that human and murine platelets have extensive and diverse transcriptomes (95). Furthermore, the platelet transcriptome and proteome are dynamic and can change in clinical disorders (96)(97)(98). Alterations in platelet RNAs (see PLATELETS IN SEPSIS AND SEPTIC ALI section below), biologically significant proteins, and protein synthetic functions occur in sepsis (E. A. Middleton and colleagues, unpublished results), and they may influence events in septic ARDS.…”

Structure and function of the ubiquitin‐proteasome system in platelets

“…Additionally, dengue virus infection leads to an enhanced expression of human leukocyte antigen (HLA) class I molecules on the platelet surface, which could be suppressed by the proteasome inhibitor bortezomib . This observation strongly supports the connection between the proteasome system and MHC class I expression in platelets.…”

High-resolution proteomics identifies potential new markers of Zika and dengue infections

“…PF4V1 is an inhibitor of angiogenesis and expressed at higher levels in Zika than in dengue patients. Consistently, it has been found down-regulated in platelets from dengue patients compared to control 18 , as high levels can promote rapid replication and propagation of the virus 19 . Indeed, the platelet count is one of the diagnostic indices used to distinguish between DENV and ZIKV infections 20 .…”