Annexin A2 on lung epithelial cell surface is recognized by severe acute respiratory syndrome-associated coronavirus spike domain 2 antibodies.
Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection causes lung failure characterized by atypical pneumonia. We previously showed that antibodies against SARS-CoV spike domain 2 (S2) in the patient sera can cross-react with human lung epithelial cells; however, the autoantigen is not yet identified. In this study, we performed proteomic studies and identified several candidate autoantigens recognized by SARS patient sera in human lung type II epithelial cell A549. Among the candidate proteins, annexin A2, which was identified by mass spectrometry analysis and had the highest score by Mascot data search, was further characterized and investigated for its role as an autoantigen. By confocal microscopic observation, SARS patient sera and anti-S2 antibodies were co-localized on A549 cells and both of them were co-localized with anti-annexin A2 antibodies. Anti-annexin A2 antibodies bound to purified S2 proteins, and anti-S2 bound to immunoprecipitated annexin A2 from A549 cell lysate in a dose-dependent manner. Furthermore, an increased surface expression and raft-structure distribution of annexin A2 was present in A549 cells after stimulation with SARS-induced cytokines interleukin-6 and interferon-gamma. Cytokine stimulation increased the binding capability of anti-S2 antibodies to human lung epithelial cells. Together, the upregulated expression of annexin A2 by SARS-associated cytokines and the cross-reactivity of anti-SARS-CoV S2 antibodies to annexin A2 may have implications in SARS disease pathogenesis.
Fang
Yi-Ting
YT
Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan, Taiwan.
Lin
Chiou-Feng
CF
Liao
Pao-Chi
PC
Kuo
Yu-Min
YM
Wang
Shuying
S
Yeh
Trai-Ming
TM
Shieh
Chi-Chang K
CC
Su
Ih-Jen
IJ
Lei
Huan-Yao
HY
Lin
Yee-Shin
YS
D017306:Annexin A2 / Q000276:immunology*; D000914:Antibodies, Viral / Q000276:immunology*; D000998:Antiviral Agents / Q000494:pharmacology; D001324:Autoantigens / Q000276:immunology*; D045744:Cell Line, Tumor; D003429:Cross Reactions / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology* / Q000473:pathology / Q000821:virology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000276:immunology*; D017434:Protein Structure, Tertiary; D020545:Respiratory Mucosa / Q000276:immunology* / Q000473:pathology / Q000821:virology; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology*; D045169:Severe Acute Respiratory Syndrome / Q000276:immunology* / Q000473:pathology / Q000821:virology; D064370:Spike Glycoprotein, Coronavirus; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D014759:Viral Envelope Proteins / Q000276:immunology*
C472822:ANXA2 protein, human; D017306:Annexin A2; D000914:Antibodies, Viral; D000998:Antiviral Agents; D001324:Autoantigens; C508600:IL6 protein, human; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D064370:Spike Glycoprotein, Coronavirus; D014759:Viral Envelope Proteins; D007371:Interferon-gamma