Proteomic Analysis of Endothelial Cell Autoantigens Recognized by Anti-Dengue Virus Nonstructural Protein 1 Antibodies

The Journal of Immunology

Lei³

et al. 2009

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The mechanisms underlying dengue hemorrhagic disease are incompletely understood. We previously showed that anti-dengue virus (DV) nonstructural protein 1 (NS1) Abs cross-react with human platelets and inhibit platelet aggregation. Based on sequence homology alignment, the cross-reactive epitopes reside in the C-terminal region of DV NS1. In this study, we compared the effects of Abs against full-length DV NS1 and NS1 lacking the C-terminal aa 271 to 352 (designated ΔC NS1). Anti-ΔC NS1 Abs exhibited lower platelet binding activity than that of anti-full-length NS1. Anti-full-length NS1 but not anti-ΔC NS1 Abs inhibited platelet aggregation, which was shown to involve integrin αIIbβ3 inactivation. We found that the bleeding time in full-length NS1-hyperimmunized mice was longer than that in the normal control mice. By contrast, ΔC NS1-hyperimmunized mice showed a bleeding time similar to that of normal control mice. Passively administered anti-DV NS1, but not anti-ΔC NS1, Ab level decreased markedly in serum and this decrease was correlated with Ab binding to platelets. A transient platelet loss in the circulation was observed after anti-DV NS1, but not anti-ΔC NS1, Ab administration. In summary, platelet dysfunction and bleeding tendency are induced by anti-full-length DV NS1 but not by anti-ΔC NS1 Abs. These findings may be important not only for understanding dengue hemorrhagic disease pathogenesis but also for dengue vaccine development.

Section: Nfection With Dengue Viruses (Dv)mentioning

confidence: 99%

Deletion of the C-Terminal Region of Dengue Virus Nonstructural Protein 1 (NS1) Abolishes Anti-NS1-Mediated Platelet Dysfunction and Bleeding Tendency

Chen¹,

The Journal of Immunology

Lei³

et al. 2009

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“…Antibodies induced by molecular mimicry between DENV and human proteins can cross-react with platelets, coagulation factors, and endothelial cells. These autoantibodies may contribute to thrombocytopenia, abnormal coagulation and fibrinolysis, and endothelial damage in DHF/DSS patients, causing hemorrhage (16,18,32,44). However, other factors, such as proinflammatory cytokines and secreted NS1, may also contribute to the development of hemorrhage during the acute stage of DENV infection (37,(45)(46)(47)(48).…”

Section: Discussionmentioning

confidence: 99%

“…An additional hypothesis has been proposed, suggesting that the autoimmunity of anti-DENV antibodies contributes to the pathogenesis of DHF/DSS (14,15). Many anti-DENV antibodies that are able to cross-react with human tissues have been found (16,17). For example, anti-NS1 antibodies can bind to platelets and cause thrombocytopenia in mice (18,19).…”

mentioning

confidence: 99%

Molecular Mimicry between Dengue Virus and Coagulation Factors Induces Antibodies To Inhibit Thrombin Activity and Enhance Fibrinolysis

Chuang

Liu

et al. 2014

J Virol

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Dengue virus (DENV) is the most common cause of viral hemorrhagic fever, and it may lead to life-threating dengue hemorrhagic fever and shock syndrome (DHF/DSS). Because most cases of DHF/DSS occur in patients with secondary DENV infection, anti-DENV antibodies are generally considered to play a role in the pathogenesis of DHF/DSS. Previously, we have found that antithrombin antibodies (ATAs) with both antithrombotic and profibrinolytic activities are present in the sera of dengue patients. However, the mechanism by which these autoantibodies are induced is unclear. In this study, we demonstrated that antibodies induced by DENV immunization in mice and rabbits could bind to DENV antigens as well as to human thrombin and plasminogen (Plg). The binding of anti-DENV antibodies to thrombin and Plg was inhibited by preadsorption with DENV nonstructural protein 1. In addition, affinity-purified ATAs from DENV-immunized rabbit sera could inhibit thrombin activity and enhance Plg activation both in vitro and in vivo. Taken together, our results suggest that molecular mimicry between DENV and coagulation factors can induce the production of autoantibodies with biological effects similar to those of ATAs found in dengue patients. These coagulation-factor cross-reactive anti-DENV antibodies can interfere with the balance of coagulation and fibrinolysis, which may lead to the tendency of DHF/DSS patients to bleed. IMPORTANCE Dengue virus (DENV) infection is the most common mosquito-borne viral disease in tropical and subtropical areas. Over 50million DENV infection cases develop each year, and more than 2.5 billion people are at risk of dengue-induced hemorrhagic fever and shock syndrome. Currently, there is no vaccine or drug treatment for DENV. In the present study, we demonstrated that DENV immunization could induce thrombin and plasminogen (Plg) cross-reactive antibodies, which were able to inhibit thrombin activity and enhance Plg activation. These results suggest that molecular mimicry between DENV antigens, thrombin, and Plg may elicit antibodies that disturb hemostasis. The selection of appropriate candidate antigens for use in DENV vaccines should prevent these potentially dangerous autoimmune responses.

“…Given the pathological effects reported for anti-NS1 Abs, the underlying mechanisms need to be characterized and the relevant epitopes identified. Considerable progress toward these goals has been achieved (30,(65)(66)(67)(68), raising the hope that safer NS1 candidate vaccines may be developed with modified or deleted harmful epitopes such as those involved in autoimmune responses.…”

Section: Discussionmentioning

confidence: 99%

Anti–Dengue Virus Nonstructural Protein 1 Antibodies Cause NO-Mediated Endothelial Cell Apoptosis via Ceramide-Regulated Glycogen Synthase Kinase-3β and NF-κB Activation

Chen

The Journal of Immunology

Wan

et al. 2013

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Immunopathogenetic mechanisms of dengue virus (DENV) infection are involved in hemorrhagic syndrome resulting from thrombocytopenia, coagulopathy, and vasculopathy. We have proposed a mechanism of molecular mimicry in which Abs against DENV nonstructural protein 1 (NS1) cross-react with human endothelial cells and cause NF-κB–regulated immune activation and NO-mediated apoptosis. However, the signaling pathway leading to NF-κB activation after the binding of anti-DENV NS1 Abs to endothelial cells is unresolved. In this study, we found that anti-DENV NS1 Abs caused the formation of lipid raftlike structures, and that disrupting lipid raft formation by methyl-β-cyclodextrin decreased NO production and apoptosis. Treatment with anti-DENV NS1 Abs elevated ceramide generation in lipid rafts. Pharmacological inhibition of acid sphingomyelinase (aSMase) decreased anti-DENV NS1 Ab-mediated ceramide and NO production, as well as apoptosis. Exogenous ceramide treatment induced biogenesis of inducible NO synthase (iNOS)/NO and apoptosis through an NF-κB–regulated manner. Furthermore, activation of glycogen synthase kinase-3β (GSK-3β) was required for ceramide-induced NF-κB activation and iNOS expression. Notably, anti-DENV NS1 Abs caused GSK-3β–mediated NF-κB activation and iNOS expression, which were regulated by aSMase. Moreover, pharmacological inhibition of GSK-3β reduced hepatic endothelial cell apoptosis in mice passively administered anti-DENV NS1 Abs. These results suggest that anti-DENV NS1 Abs bind to the endothelial cell membrane and cause NO production and apoptosis via a mechanism involving the aSMase/ceramide/GSK-3β/NF-κB/iNOS/NO signaling pathway.