Induction of indoleamine 2, 3-dioxygenase in human dendritic cells by a cholera toxin B subunit-proinsulin vaccine

• Published in: PloS one 2015-02, Vol.10 (2), p.e0118562
• Main Authors: Mbongue, Jacques C, Nicholas, Dequina A, Zhang, Kangling, Kim, Nan-Sun, Hamilton, Brittany N, Larios, Marco, Zhang, Guangyu, Umezawa, Kazuo, Firek, Anthony F, Langridge, William H R
• Format: Article
• Language: English
• Subjects: Antigens; Autoimmune diseases; Autoimmunity; Bar codes; Biochemistry; Biosynthesis; Cell Differentiation; Cholera; Cholera toxin; Cholera Toxin - genetics; Cholera Toxin - immunology; Cholera toxin B subunit; Cluster Analysis; Cytokines; Degradation products; Dendritic cells; Dendritic Cells - cytology; Dendritic Cells - immunology; Dendritic Cells - metabolism; Dendritic structure; Diabetes; Diabetes mellitus; Diabetes mellitus (insulin dependent); Dioxygenase; Disease; Enzymes; Fusion protein; Gene Expression Profiling; Health disparities; Homeostasis; Humans; Hydrocarbons; Hyperglycemia; Immune system; Immunity; Immunological tolerance; Immunology; Immunosuppression; Indoleamine-Pyrrole 2,3,-Dioxygenase - biosynthesis; Indoleamine-Pyrrole 2,3,-Dioxygenase - genetics; Infections; Inflammation; Inoculation; Insulin; Kinases; Lymphocytes; Lymphocytes T; Maturation; Medicine; Monocytes; Monocytes - cytology; Monocytes - metabolism; Mucosa; NF-kappa B - metabolism; NF-κB protein; Pancreas; Pharmacology; Physiological aspects; Proinsulin - genetics; Proinsulin - immunology; Protein biosynthesis; Protein synthesis; Proteins; Proteome; Proteomics; Public health; Signal Transduction; T cells; Therapeutic applications; Toxins; Tryptophan; Type 1 diabetes; Vaccination; Vaccine efficacy; Vaccines; Vaccines, Subunit - genetics; Vaccines, Subunit - immunology; Vibrio cholerae; Waterborne diseases
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0118562

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.