Dengue virus nonstructural protein 1 activates platelets via Toll-like receptor 4, leading to thrombocytopenia and hemorrhage

• Published in: PLoS pathogens 2019-04, Vol.15 (4), p.e1007625-e1007625
• Main Authors: Chao, Chiao-Hsuan, Wu, Wei-Chueh, Lai, Yen-Chung, Tsai, Pei-Jane, Perng, Guey-Chuen, Lin, Yee-Shin, Yeh, Trai-Ming
• Format: Article
• Language: English
• Subjects: Activation; Adenosine; Adenosine diphosphate; Animals; Antibodies; Apoptosis; Aquatic insects; ATPases; Biology and Life Sciences; Biotechnology; Blood platelets; Blood Platelets - immunology; Blood Platelets - metabolism; Blood Platelets - pathology; Cell culture; Cells, Cultured; Dengue - complications; Dengue - metabolism; Dengue - virology; Dengue fever; Dengue hemorrhagic fever; Dengue virus; Dengue Virus - immunology; Depletion; Development and progression; Disease transmission; Endothelial cells; Endothelium; Hemorrhage; Hemorrhage - etiology; Hemorrhage - metabolism; Hemorrhage - pathology; Hemorrhagic fevers; Humans; Immune system; Immunology; Immunotherapy; Infection; Infections; Inhibitors; Lipopolysaccharides; Lipopolysaccharides - toxicity; Macrophages; Macrophages - immunology; Macrophages - metabolism; Macrophages - pathology; Medical laboratories; Medical research; Medicine; Medicine and Health Sciences; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mitogens; Mosquitoes; P-selectin; Pathogenesis; Phagocytosis; Phosphatidylserine; Phospholipids; Platelet aggregation; Platelets; Polymyxin B; Proteins; Research and Analysis Methods; Risk factors; Serotypes; Shock; Signal transduction; Thrombocytopenia; Thrombocytopenia - etiology; Thrombocytopenia - metabolism; Thrombocytopenia - pathology; TLR4; TLR4 protein; Toll-Like Receptor 4 - metabolism; Toll-like receptors; Vector-borne diseases; Viral diseases; Viral infections; Viral Nonstructural Proteins - metabolism; Virus diseases; Viruses; Zika virus
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1007625

Dengue virus (DENV) infection, the most common mosquito-transmitted viral infection, can cause a range of diseases from self-limiting dengue fever to life-threatening dengue hemorrhagic fever and shock syndrome. Thrombocytopenia is a major characteristic observed in both mild and severe dengue disease and is significantly correlated with the progression of dengue severity. Previous studies have shown that DENV nonstructural protein 1 (NS1), which can be secreted into patients' blood, can stimulate immune cells via Toll-like receptor 4 (TLR4) and can cause endothelial leakage. However, it is unclear whether DENV NS1 can directly induce platelet activation or cause thrombocytopenia during DENV infection. In this study, we first demonstrated that DENV but not Zika virus cell culture supernatant could induce P-selectin expression and phosphatidylserine (PS) exposure in human platelets, both of which were abolished when NS1 was depleted from the DENV supernatant. Similar results were found using recombinant NS1 from all four serotypes of DENV, and those effects were blocked in the presence of anti-NS1 F(ab')2, anti-TLR4 antibody, a TLR4 antagonist (Rhodobacter sphaeroides lipopolysaccharide, LPS-Rs) and a TLR4 signaling inhibitor (TAK242), but not polymyxin B (an LPS inhibitor). Moreover, the activation of platelets by DENV NS1 promoted subthreshold concentrations of adenosine diphosphate (ADP)-induced platelet aggregation and enhanced platelet adhesion to endothelial cells and phagocytosis by macrophages. Finally, we demonstrated that DENV-induced thrombocytopenia and hemorrhage were attenuated in TLR4 knockout and wild-type mice when NS1 was depleted from DENV supernatant. Taken together, these results suggest that the binding of DENV NS1 to TLR4 on platelets can trigger its activation, which may contribute to thrombocytopenia and hemorrhage during dengue infection.