Novel Antigen-Specific Immunomodulatory Tregitope-based Therapy to Address Autoimmune Pathogenesis in Graves' Disease

ABSTRACT SignificanceGravesdiseaseGDone of the most prevalent autoimmune diseasesis caused by stimulating autoantibodiesTSAbto the Thyroid Stimulating Hormone ReceptorTSHRresulting in hyperthyroidismCurrent methods for managing hyperthyroidism in GD target excess thyroid hormone secretion by ablation or removal of the thyroid or by blocking thyroid hormone synthesisEach of these therapies is associated with adverse effectsmost commonly hypothyroidism requiring life long replacement therapyImportantlynone of these approaches address the underlying anti TSHR CDT cell response that contributes to the continued production of TSAb auto antibodiesAutoimmunity is the result of an imbalance in Teffector TregulatoryTeff Tregimmune cell homeostasisand a loss of central or peripheral immune toleranceT regulatory epitopesTregitopesfound in IgG stimulate proliferation and activation of natural and induced Tregsthereby downregulating a Teff response to self antigensThese Tregitopes when administered with MHC Class II binding self antigen peptideswill elicit AntigenSpecific Adaptive Tolerance InductionASATIHypothesisTregitopesin combination with the target antigenTSHR CDT cell effector peptideswill reduce CDT cell activation and T dependent B cell production of TSAbDue to the short half life of peptides in vivoa practical Tregitope BioTherapeuticTreg BTwill need to be administered in a suitable delivery systemthat improves its PK PD properties with minimal toxicityThis project will identify TSHR peptides that stimulate a CDeffector immune response in PBMC from GD patientsand combine the optimal peptide swith Tregitopes in an effective delivery vehicleIn Specific AimTSHR peptides identified to stimulate a CDeffector cell response in GD patients will be tested for inhibition by Tregitopes in a TSHR bystander suppression assayTregitope peptides with and without TSHR peptides will then be formulated into two Treg BT delivery vehiclesachemically ligated to a recombinant FDA approved human serum albuminHSAor bformulated into poly lactic glycolic acidPLGAmicrospheresThe Treg BT will then be tested in the TSHR bystander suppression assay with PBMC from GD patientsIn Specific Aimthe candidate Treg BTHSATregitopeTSHR peptide or TregitopeTSHR peptides in microsphereswith appropriate controlswill be tested in vivo in a mouse model of GDHLA DRmice will be genetically immunized with an expression plasmid coding for the extracellular domain of TSHR to generate TSAbAfter TSAb response is establishedthe mice will be treated with the optimized Treg BT and serum TSAb and CDT cell responses will be monitoredOverall ImpactThese studies will produce candidate Treg BT whichcombined with TSHR peptidesstimulate a Treg mediated down regulation of TSAb autoantibodieswith potential fast track applicability to the treatment of patients with clinical Gravesdisease