title: Impaired immune regulation after radioiodine therapy for Graves' disease and the protective effect of Methimazole.
abstract: Both therapies for Graves' disease (GD), radioactive iodine (RAI) and antithyroid drugs (ATD), were reported to have specific immune effects. We aimed at investigating the effects of RAI therapy on cellular subsets involved in immune regulation. We conducted a thirty day follow-up prospective cohort study of adult patients. Patients eligible for RAI therapy at our centre were approached. Twenty seven patients with GD were recruited, among whom 11 were treated with ATD. Twenty-two healthy subjects (HS) were also studied. Over time, frequency of regulatory T cells (Treg) and of invariant natural killer T cells (iNKT), along with Treg cell-mediated suppression and underlying mechanisms, were monitored in the peripheral blood. Variance in frequency of Treg and iNKT after RAI therapy was higher in GD patients than in HS over time (p < 0.0001). Reduced Treg suppressive function was observed after RAI therapy in GD patients (p = 0.002). ATD medication prior to RAI dampened these outcomes: less variation of Treg frequency (p = 0.0394), a trend toward less impaired Treg function, and prevention of reduced levels of suppressive cytokines (p < 0.05). Shortly after RAI therapy, alterations in immunoregulatory cells in patients with GD were observed and partially prevented by an ATD pretreatment. Worsening of autoimmunity after RAI was explained in previous studies by enhanced immune activity. This study adds new highlights on immune regulation deficiencies after therapeutic interventions in thyroid autoimmunity.
authors.affiliation: Department of Pediatrics, Sherbrooke University Hospital and Faculty of Medicine, 3001, 12e Avenue Nord, Sherbrooke, QC, JIH5N4, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Côté-Bigras
authors.affiliation: Department of Pediatrics, Sherbrooke University Hospital and Faculty of Medicine, 3001, 12e Avenue Nord, Sherbrooke, QC, JIH5N4, Canada.
authors.forename: Viet
authors.initials: V
authors.lastname: Tran
authors.affiliation: Department of Pediatrics, Sherbrooke University Hospital and Faculty of Medicine, 3001, 12e Avenue Nord, Sherbrooke, QC, JIH5N4, Canada.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Turcotte
authors.affiliation: Department of Pediatrics, Sherbrooke University Hospital and Faculty of Medicine, 3001, 12e Avenue Nord, Sherbrooke, QC, JIH5N4, Canada.
authors.forename: Marek
authors.initials: M
authors.lastname: Rola-Pleszczynski
authors.affiliation: Department of Nuclear Medicine and Radiobiology, Sherbrooke University Hospital and Faculty of Medicine, Sherbrooke, QC, JIH5N4, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Verreault
authors.affiliation: Department of Pediatrics, Sherbrooke University Hospital and Faculty of Medicine, 3001, 12e Avenue Nord, Sherbrooke, QC, JIH5N4, Canada. diane.rottembourg@usherbrooke.ca.
authors.forename: Diane
authors.initials: D
authors.lastname: Rottembourg
mesh_terms: D000328:Adult; D000368:Aged; D013956:Antithyroid Agents / Q000627:therapeutic use; D015551:Autoimmunity / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects* / Q000276:immunology; D005260:Female; D006111:Graves Disease / Q000188:drug therapy* / Q000276:immunology / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D007694:Killer Cells, Natural / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008297:Male; D008713:Methimazole / Q000627:therapeutic use*; D008875:Middle Aged; D011832:Radiation Injuries / Q000517:prevention & control*; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects* / Q000276:immunology / Q000528:radiation effects*; D055815:Young Adult
chemical_list: D013956:Antithyroid Agents; D007457:Iodine Radioisotopes; D008713:Methimazole
keywords: Antithyroid drugs; Graves’ disease; Natural killer T cells; Radioactive iodine; Regulatory T cells