title: Enhanced suppression of polyclonal CD8+25+regulatory T cells via exosomal arming of antigen-specific peptide/MHC complexes.
abstract: Compared with CD4+25+regulatory T cells (Tregs), the mechanisms for natural, polyclonal CD8+25+Tregimmune suppression have been significantly less studied. We previously showed that polyclonal T cells can acquire antigen-specific targeting activity through arming with exosomal peptide-MHC (pMHC). In this study, we assessed the suppressive effect of CD8+25+Tregsor CD8+25+Tregsarmed with ovalbumin (OVA)-specific exosomes on other immune cells and OVA-specific dendritic cell (DCOVA)-stimulated antitumor immunity. We demonstrate that CD8+25+Tregsinhibit T cell proliferation in vitro in a cell contact-dependent fashion but independent of the expression of immunosuppressive IL-10, TGF-β, and CTLA-4. CD8+25+Tregsanergize naïve T cells upon stimulation by up-regulating T cell anergy-associatedEgr2and down-regulating IL-2 production. Tregsalso anergize DCs by preventing DC maturation through the down-regulation of Iab, CD80, CD86, and inflammatory cytokines, leading to defects in T cell stimulation. Moreover, CD8+25+Tregsinhibit CTLs through inducing CTL death via perforin-mediated apoptosis and through reducing effector CTL cytotoxic activity via down-regulating CTL perforin-production and degranulation. In addition, we show that CD8+25+Tregssuppress DCOVA-stimulated CTL responses in priming and effector phases and inhibit immunity against OVA-expressing CCLOVAlung cancer. Remarkably, polyclonal CD8+25+Tregsarmed with OVA-specific exosomal pMHC class-II (pMHC-II), or pMHC class-I (pMHC-I) complexes exert their enhanced inhibition of CTL responses in the priming and the effector phases, respectively. Taken together, our investigation reveals that assigning antigen specificity to nonspecific polyclonal CD8+25+Tregsfor enhanced immune suppression can be achieved through exosomal pMHC arming. This principle may have a great effect on Treg-mediated immunotherapy of autoimmune diseases.
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital, Soochow University, Soochow, China.
authors.forename: Chuanyong
authors.initials: C
authors.lastname: Mu
authors.affiliation: Cancer Research Department, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.|Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Xueshu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Cancer Research Department, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.|Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Cancer Research Department, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.|Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Aizhang
authors.initials: A
authors.lastname: Xu
authors.affiliation: Cancer Research Department, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.|Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Khawaja Ashfaque
authors.initials: KA
authors.lastname: Ahmed
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital, Soochow University, Soochow, China.
authors.forename: Xueqin
authors.initials: X
authors.lastname: Pang
authors.affiliation: Department of Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Rajni
authors.initials: R
authors.lastname: Chibbar
authors.affiliation: Department of Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Freywald
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital, Soochow University, Soochow, China.
authors.forename: Jianan
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Respiratory Medicine, The First Affiliated Hospital, Soochow University, Soochow, China; zhuyehan@suda.edu.cn.
authors.forename: Yehan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Cancer Research Department, Saskatchewan Cancer Agency, University of Saskatchewan, Saskatoon, Saskatchewan, Canada jim.xiang@usask.ca.|Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Jim
authors.initials: J
authors.lastname: Xiang
mesh_terms: D000818:Animals; D018122:B7-1 Antigen / Q000235:genetics / Q000276:immunology; D051940:B7-2 Antigen / Q000235:genetics / Q000276:immunology; D060908:CTLA-4 Antigen / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D017635:Clonal Anergy; D003602:Cytotoxicity, Immunologic; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D051767:Early Growth Response Protein 2 / Q000235:genetics / Q000276:immunology; D055354:Exosomes / Q000737:chemistry / Q000276:immunology*; D005786:Gene Expression Regulation; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology*; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology; D007376:Interleukin-2 / Q000235:genetics / Q000276:immunology; D008175:Lung Neoplasms / Q000235:genetics / Q000276:immunology* / Q000401:mortality / Q000473:pathology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009368:Neoplasm Transplantation; D010047:Ovalbumin / Q000494:pharmacology; D061251:Primary Cell Culture; D015398:Signal Transduction; D016019:Survival Analysis; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000276:immunology
chemical_list: D018122:B7-1 Antigen; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; C497965:Cd86 protein, mouse; D051767:Early Growth Response Protein 2; C497327:Egr2 protein, mouse; D015395:Histocompatibility Antigens Class I; C556062:IL10 protein, mouse; D007376:Interleukin-2; D016212:Transforming Growth Factor beta; D016753:Interleukin-10; D010047:Ovalbumin
keywords: CD8+25+ Tregs; CTL; dendritic cells; exosomal arming; pMHC complex