title: Induction of indoleamine 2, 3-dioxygenase in human dendritic cells by a cholera toxin B subunit-proinsulin vaccine.
abstract: Dendritic cells (DC) interact with naïve T cells to regulate the delicate balance between immunity and tolerance required to maintain immunological homeostasis. In this study, immature human dendritic cells (iDC) were inoculated with a chimeric fusion protein vaccine containing the pancreatic β-cell auto-antigen proinsulin linked to a mucosal adjuvant the cholera toxin B subunit (CTB-INS). Proteomic analysis of vaccine inoculated DCs revealed strong up-regulation of the tryptophan catabolic enzyme indoleamine 2, 3-dioxygenase (IDO1). Increased biosynthesis of the immunosuppressive enzyme was detected in DCs inoculated with the CTB-INS fusion protein but not in DCs inoculated with proinsulin, CTB, or an unlinked combination of the two proteins. Immunoblot and PCR analyses of vaccine treated DCs detected IDO1mRNA by 3 hours and IDO1 protein synthesis by 6 hours after vaccine inoculation. Determination of IDO1 activity in vaccinated DCs by measurement of tryptophan degradation products (kynurenines) showed increased tryptophan cleavage into N-formyl kynurenine. Vaccination did not interfere with monocytes differentiation into DC, suggesting the vaccine can function safely in the human immune system. Treatment of vaccinated DCs with pharmacological NF-κB inhibitors ACHP or DHMEQ significantly inhibited IDO1 biosynthesis, suggesting a role for NF-κB signaling in vaccine up-regulation of dendritic cell IDO1. Heat map analysis of the proteomic data revealed an overall down-regulation of vaccinated DC functions, suggesting vaccine suppression of DC maturation. Together, our experimental data indicate that CTB-INS vaccine induction of IDO1 biosynthesis in human DCs may result in the inhibition of DC maturation generating a durable state of immunological tolerance. Understanding how CTB-INS modulates IDO1 activity in human DCs will facilitate vaccine efficacy and safety, moving this immunosuppressive strategy closer to clinical applications for prevention of type 1 diabetes autoimmunity.
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America; Loma Linda University School of Medicine, Department of Basic Sciences, Division of Physiology, Loma Linda, CA, United States of America.
authors.forename: Jacques C
authors.initials: JC
authors.lastname: Mbongue
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America; Mass Spectrometer Core Facility, Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda University School of Medicine, Department of Basic Sciences, Loma Linda, CA, United States of America.
authors.forename: Dequina A
authors.initials: DA
authors.lastname: Nicholas
authors.affiliation: Mass Spectrometer Core Facility, Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda University School of Medicine, Department of Basic Sciences, Loma Linda, CA, United States of America; Department of Pharmacology and Toxicology, School of Medicine, University of Texas Medical Branch, Galveston, TX, United States of America.
authors.forename: Kangling
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America; Mass Spectrometer Core Facility, Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda University School of Medicine, Department of Basic Sciences, Loma Linda, CA, United States of America; Department of Molecular Biology, Chonbuk National University, Jeon-Ju, Republic of Korea.
authors.forename: Nan-Sun
authors.initials: NS
authors.lastname: Kim
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America; Loma Linda University School of Medicine, Department of Basic Sciences, Division of Microbiology and Molecular Genetics, Loma Linda, CA, United States of America.
authors.forename: Brittany N
authors.initials: BN
authors.lastname: Hamilton
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America.
authors.forename: Marco
authors.initials: M
authors.lastname: Larios
authors.affiliation: Mass Spectrometer Core Facility, Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda University School of Medicine, Department of Basic Sciences, Loma Linda, CA, United States of America.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Aichi Medical University, School of Medicine, Department of Molecular Target Medicine Screening, Nagakute, Aichi, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Umezawa
authors.affiliation: Endocrinology Section, JL Pettis Memorial VA Medical Center, Loma Linda, CA, United States of America.
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Firek
authors.affiliation: Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, United States of America; Mass Spectrometer Core Facility, Department of Biochemistry, Loma Linda University School of Medicine, Loma Linda University School of Medicine, Department of Basic Sciences, Loma Linda, CA, United States of America.
authors.forename: William H R
authors.initials: WH
authors.lastname: Langridge
mesh_terms: D002454:Cell Differentiation; D002772:Cholera Toxin / Q000235:genetics / Q000276:immunology*; D016000:Cluster Analysis; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D020869:Gene Expression Profiling; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000096:biosynthesis* / Q000235:genetics; D009000:Monocytes / Q000166:cytology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D011384:Proinsulin / Q000235:genetics / Q000276:immunology*; D020543:Proteome; D040901:Proteomics; D015398:Signal Transduction; D022223:Vaccines, Subunit / Q000235:genetics / Q000276:immunology*
chemical_list: D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D016328:NF-kappa B; D020543:Proteome; D022223:Vaccines, Subunit; D002772:Cholera Toxin; D011384:Proinsulin