title: Increased expression of Toll-like receptors 7 and 9 in myasthenia gravis thymus characterized by active Epstein-Barr virus infection.
abstract: Considerable data implicate the thymus as the main site of autosensitization to the acetylcholine receptor in myasthenia gravis (MG), a B-cell-mediated autoimmune disease affecting the neuromuscular junction. We recently demonstrated an active Epstein-Barr virus (EBV) infection in the thymus of MG patients, suggesting that EBV might contribute to the onset or maintenance of the autoimmune response within MG thymus, because of its ability to activate and immortalize autoreactive B cells. EBV has been reported to elicit and modulate Toll-like receptor (TLR) 7- and TLR9-mediated innate immune responses, which are known to favor B-cell dysfunction and autoimmunity. Aim of this study was to investigate whether EBV infection is associated with altered expression of TLR7 and TLR9 in MG thymus. By real-time PCR, we found that TLR7 and TLR9 mRNA levels were significantly higher in EBV-positive MG compared to EBV-negative normal thymuses. By confocal microscopy, high expression levels of TLR7 and TLR9 proteins were observed in B cells and plasma cells of MG thymic germinal centers (GCs) and lymphoid infiltrates, where the two receptors co-localized with EBV antigens. An increased frequency of Ki67-positive proliferating B cells was found in MG thymuses, where we also detected proliferating cells expressing TLR7, TLR9 and EBV antigens, thus supporting the idea that EBV-associated TLR7/9 signaling may promote abnormal B-cell activation and proliferation. Along with B cells and plasma cells, thymic epithelium, plasmacytoid dendritic cells and macrophages exhibited enhanced TLR7 and TLR9 expression in MG thymus; TLR7 was also increased in thymic myeloid dendritic cells and its transcriptional levels positively correlated with those of interferon (IFN)-β. We suggested that TLR7/9 signaling may be involved in antiviral type I IFN production and long-term inflammation in EBV-infected MG thymuses. Our overall findings indicate that EBV-driven TLR7- and TLR9-mediated innate immune responses may participate in the intra-thymic pathogenesis of MG.
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: pcavalcante@istituto-besta.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Cavalcante
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: barbara.galbardi@istituto-besta.it.
authors.forename: Barbara
authors.initials: B
authors.lastname: Galbardi
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: sara.franzi@istituto-besta.it.
authors.forename: Sara
authors.initials: S
authors.lastname: Franzi
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: stefania.marcuzzo@istituto-besta.it.
authors.forename: Stefania
authors.initials: S
authors.lastname: Marcuzzo
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: claudia.barzago@istituto-besta.it.
authors.forename: Claudia
authors.initials: C
authors.lastname: Barzago
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: silvia.bonanno@istituto-besta.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bonanno
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: giorgia.camera@istituto-besta.it.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Camera
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: lorenzo.maggi@istituto-besta.it.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Maggi
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: dimos.kapetis@istituto-besta.it.
authors.forename: Dimos
authors.initials: D
authors.lastname: Kapetis
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: francesca.andreetta@istituto-besta.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Andreetta
authors.affiliation: Department of Pathological Anatomy, Azienda Ospedaliera Bolognini Seriate, Via Paterno 21, 24068, Seriate Bergamo, Italy. Electronic address: amelia.biasiucci@bolognini.bg.it.
authors.forename: Amelia
authors.initials: A
authors.lastname: Biasiucci
authors.affiliation: Department of Pathological Anatomy, Azienda Ospedaliera Bolognini Seriate, Via Paterno 21, 24068, Seriate Bergamo, Italy. Electronic address: teresio.motta@bolognini.bg.it.
authors.forename: Teresio
authors.initials: T
authors.lastname: Motta
authors.affiliation: Department of Pathological Anatomy, Azienda Ospedaliera Bolognini Seriate, Via Paterno 21, 24068, Seriate Bergamo, Italy. Electronic address: anatomiapat.seriate@bolognini.bg.it.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Giardina
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: carlo.antozzi@istituto-besta.it.
authors.forename: Carlo
authors.initials: C
authors.lastname: Antozzi
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: fulvio.baggi@istituto-besta.it.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Baggi
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: rmantegazza@istituto-besta.it.
authors.forename: Renato
authors.initials: R
authors.lastname: Mantegazza
authors.affiliation: Neurology IV-Neuroimmunology and Neuromuscular Diseases Unit, Fondazione Istituto Neurologico "Carlo Besta", Via Celoria 11, 20133 Milan, Italy. Electronic address: pbernasconi@istituto-besta.it.
authors.forename: Pia
authors.initials: P
authors.lastname: Bernasconi
mesh_terms: D000293:Adolescent; D000328:Adult; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology / Q000473:pathology / Q000821:virology; D049109:Cell Proliferation; D003713:Dendritic Cells / Q000276:immunology / Q000473:pathology / Q000821:virology; D020031:Epstein-Barr Virus Infections / Q000150:complications / Q000276:immunology* / Q000473:pathology / Q000821:virology; D005260:Female; D005786:Gene Expression Regulation; D018858:Germinal Center / Q000276:immunology / Q000473:pathology / Q000821:virology; D004854:Herpesvirus 4, Human; D006801:Humans; D016899:Interferon-beta / Q000235:genetics / Q000276:immunology; D019394:Ki-67 Antigen / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology / Q000473:pathology / Q000821:virology; D008297:Male; D009157:Myasthenia Gravis / Q000150:complications / Q000276:immunology* / Q000473:pathology / Q000821:virology; D012333:RNA, Messenger / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction; D013950:Thymus Gland / Q000276:immunology* / Q000473:pathology / Q000821:virology; D051199:Toll-Like Receptor 7 / Q000235:genetics / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000276:immunology*
chemical_list: D000956:Antigens, Viral; D019394:Ki-67 Antigen; D012333:RNA, Messenger; C495348:TLR7 protein, human; C495371:TLR9 protein, human; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; D016899:Interferon-beta
keywords: Epstein–Barr virus; Myasthenia gravis; Thymus; Toll-like receptor 7; Toll-like receptor 9