Dengue virus NS1 protein activates cells via Toll-like receptor 4 and disrupts endothelial cell monolayer integrity.
Complications arising from dengue virus infection include potentially fatal vascular leak, and severe disease has been linked with excessive immune cell activation. An understanding of the triggers of this activation is critical for the development of appropriately targeted disease control strategies. We show here that the secreted form of the dengue virus nonstructural protein 1 (NS1) is a pathogen-associated molecular pattern (PAMP). Highly purified NS1 devoid of bacterial endotoxin activity directly activated mouse macrophages and human peripheral blood mononuclear cells (PBMCs) via Toll-like receptor 4 (TLR4), leading to the induction and release of proinflammatory cytokines and chemokines. In an in vitro model of vascular leak, treatment with NS1 alone resulted in the disruption of endothelial cell monolayer integrity. Both NS1-mediated activation of PBMCs and NS1-induced vascular leak in vitro were inhibited by a TLR4 antagonist and by anti-TLR4 antibody treatment. The importance of TLR4 activation in vivo was confirmed by the reduction in capillary leak by a TLR4 antagonist in a mouse model of dengue virus infection. These results pinpoint NS1 as a viral toxin counterpart of the bacterial endotoxin lipopolysaccharide (LPS). Similar to the role of LPS in septic shock, NS1 might contribute to vascular leak in dengue patients, which highlights TLR4 antagonists as a possible therapeutic option.
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Naphak
N
Modhiran
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia. Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
Daniel
D
Watterson
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia. Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Brisbane, Queensland 4072, Australia.
David A
DA
Muller
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Adele K
AK
Panetta
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
David P
DP
Sester
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
Lidong
L
Liu
Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
David A
DA
Hume
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia. Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia. p.young@uq.edu.au katryn.stacey@uq.edu.au.
Katryn J
KJ
Stacey
Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia. Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia. p.young@uq.edu.au katryn.stacey@uq.edu.au.
Paul R
PR
Young
D000818:Animals; D002448:Cell Adhesion; D016207:Cytokines / Q000378:metabolism; D003716:Dengue Virus / Q000378:metabolism*; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D056747:Immunomodulation; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D017361:Viral Nonstructural Proteins / Q000276:immunology*
D016207:Cytokines; D018836:Inflammation Mediators; D015850:Interleukin-6; D012333:RNA, Messenger; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D017361:Viral Nonstructural Proteins