Study on the mechanism of molecular mimicry for dengue hemorrhagic fever pathogenesis : Proteomic analysis of endothelial cell and platelet autoantigens recognized by dengue virus nonstructural protein 1 antibodies

• Main Authors: Hsien-Jen Cheng, 鄭獻仁
• Other Authors: Yee-Shin Lin
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/02430385310223704941

博士 === 國立成功大學 === 基礎醫學研究所 === 97 === Abstract Dengue virus (DV) infection may cause vascular leakage and hemorrhage. We previously showed a mechanism of molecular mimicry in which antibodies against DV nonstructural protein 1 (NS1) cross-reacted with endothelial cells and induced them to undergo apoptosis and immune activation. In this study, we found that the target proteins recognized by anti-DV NS1 antibodies on HMEC-1 endothelial cells were beta chain of H+-transporter/ATP synthase (ATPase 刍 chain), protein disulfide isomerase (PDI), vimentin intermediate filament, and heat shock protein 60 (HSP60). We confirmed their expression on the HMEC-1 cell surface. Co-localization was shown between the binding sites of anti-DV NS1 antibodies and target proteins on HMEC-1 cells. The antibodies against the target proteins cross-reacted with HMEC-1 cells, but DV NS1 protein pre-absorption inhibited cross-reaction. The cross-reactivity of anti-DV NS1 antibodies with target proteins, and vice versa, indicated a molecular mimicry mechanism. Synthetic peptides of NS1 amino acid residues 311-330 (P311-330), a predicted epitope analyzed using homologous alignments between the C-terminus of DV2 NS1 and target proteins, were bound to anti-ATPase, anti-PDI, and anti-HSP60 antibodies, but much less to anti-vimentin antibodies. The cross-reactivity of dengue hemorrhagic fever (DHF) patient sera with HMEC-1 cells was blocked by P311-330 pre-absorption, which showed that anti-DV NS1-recognized molecules on the endothelial cell surface that may be involved in the pathogenesis of dengue hemorrhage, and that P311-330 is one of the shared epitopes between DV NS1 and its target proteins. Our previous study also showed that antibodies against DV NS1 cross-reacted with platelets. In this study, we demonstrate that protein disulfide isomerase (PDI) on platelet surface is recognized by anti-DV NS1 antibodies. Anti-DV NS1 inhibited PDI activity and platelet aggregation, and both inhibitory effects were prevented when anti-DV NS1 were pre-absorbed with PDI. Anti-PDI antibodies bound to P311-330. The platelet binding activities of anti-PDI and anti-DV NS1 antibodies were reduced by P311-330 pre-absorption. Similar to the findings using anti-DV NS1, antibodies against P311-330 bound to PDI and platelets, followed by inhibition of PDI activity and platelet aggregation. Furthermore, the cross-reactivity of DHF patient sera with platelets was reduced when patient sera were pre-absorbed with PDI or P311-330. DHF patient sera also inhibited platelet aggregation, and this inhibitory effect was blocked by PDI or P311-330 pre-absorption. Therefore, anti-DV NS1 antibodies cross-react with PDI on platelet surface causing inhibition of platelet aggregation, which may have implications in dengue disease pathogenesis. Moreover, the amino acid residues 311-330 of DV NS1 possess an important epitope, which is involved in the autoimmune response of DV pathogenesis.