GAD-alum immunotherapy in type 1 diabetes expands bifunctional Th1/Th2 autoreactive CD4 T cells

TY - JOUR

T1 - GAD-alum immunotherapy in type 1 diabetes expands bifunctional Th1/Th2 autoreactive CD4 T cells

AU - Arif, Sefina

AU - Gomez-Tourino, Iria

AU - Kamra, Yogesh

AU - Pujol-Autonell, Irma

AU - Hanton, Emily

AU - Tree, Timothy

AU - Melandri, Daisy

AU - Hull, Caroline

AU - Wherrett, Diane K.

AU - Beam, Craig

AU - Roep, Bart O.

AU - Lorenc, Anna

AU - Peakman, Mark

PY - 2020/6/1

Y1 - 2020/6/1

N2 - Aims/hypothesis: Antigen-specific therapy aims to modify inflammatory T cell responses in type 1 diabetes and restore immune tolerance. One strategy employs GAD65 conjugated to aluminium hydroxide (GAD-alum) to take advantage of the T helper (Th)2-biasing adjuvant properties of alum and thereby regulate pathological Th1 autoimmunity. We explored the cellular and molecular mechanism of GAD-alum action in the setting of a previously reported randomised placebo-controlled clinical trial conducted by Type 1 Diabetes TrialNet. Methods: In the clinical trial conducted by Type 1 Diabetes TrialNet, participants were immunised with 20 μg GAD-alum (twice or three times) or alum alone and peripheral blood mononuclear cell samples were banked at baseline and post treatment. In the present study, GAD-specific T cell responses were measured in these samples and GAD-specific T cell lines and clones were generated, which were then further characterised. Results: At day 91 post immunisation, we detected GAD-specific IL-13+ CD4 T cell responses significantly more frequently in participants immunised with GAD-alum (71% and 94% treated twice or three times, respectively) compared with those immunised with alum alone (38%; p = 0.003 and p = 0.0002, respectively) accompanied by high secreted levels of IL-13, IL-4 and IL-5, confirming a GAD-specific, GAD-alum-induced Th2 response. Of note, GAD-specific, IL-13+ CD4 T cells observed after immunisation co-secreted IFN-γ, displaying a bifunctional Th1/Th2 phenotype. Single-cell transcriptome analysis identified IL13 and IFNG expression in concert with the canonical Th2 and Th1 transcription factor genes GATA3 and TBX21, respectively. T cell receptor β-chain (TCRB) CDR3 regions of GAD-specific bifunctional T cells were identified in circulating naive and central memory CD4 T cell pools of non-immunised participants with new-onset type 1 diabetes and healthy individuals, suggesting the potential for bifunctional responses to be generated de novo by GAD-alum immunisation or via expansion from an existing public repertoire. Conclusions/interpretation: GAD-alum immunisation activates and propagates GAD-specific CD4 T cells with a distinctive bifunctional phenotype, the functional analysis of which might be important in understanding therapeutic responses.

AB - Aims/hypothesis: Antigen-specific therapy aims to modify inflammatory T cell responses in type 1 diabetes and restore immune tolerance. One strategy employs GAD65 conjugated to aluminium hydroxide (GAD-alum) to take advantage of the T helper (Th)2-biasing adjuvant properties of alum and thereby regulate pathological Th1 autoimmunity. We explored the cellular and molecular mechanism of GAD-alum action in the setting of a previously reported randomised placebo-controlled clinical trial conducted by Type 1 Diabetes TrialNet. Methods: In the clinical trial conducted by Type 1 Diabetes TrialNet, participants were immunised with 20 μg GAD-alum (twice or three times) or alum alone and peripheral blood mononuclear cell samples were banked at baseline and post treatment. In the present study, GAD-specific T cell responses were measured in these samples and GAD-specific T cell lines and clones were generated, which were then further characterised. Results: At day 91 post immunisation, we detected GAD-specific IL-13+ CD4 T cell responses significantly more frequently in participants immunised with GAD-alum (71% and 94% treated twice or three times, respectively) compared with those immunised with alum alone (38%; p = 0.003 and p = 0.0002, respectively) accompanied by high secreted levels of IL-13, IL-4 and IL-5, confirming a GAD-specific, GAD-alum-induced Th2 response. Of note, GAD-specific, IL-13+ CD4 T cells observed after immunisation co-secreted IFN-γ, displaying a bifunctional Th1/Th2 phenotype. Single-cell transcriptome analysis identified IL13 and IFNG expression in concert with the canonical Th2 and Th1 transcription factor genes GATA3 and TBX21, respectively. T cell receptor β-chain (TCRB) CDR3 regions of GAD-specific bifunctional T cells were identified in circulating naive and central memory CD4 T cell pools of non-immunised participants with new-onset type 1 diabetes and healthy individuals, suggesting the potential for bifunctional responses to be generated de novo by GAD-alum immunisation or via expansion from an existing public repertoire. Conclusions/interpretation: GAD-alum immunisation activates and propagates GAD-specific CD4 T cells with a distinctive bifunctional phenotype, the functional analysis of which might be important in understanding therapeutic responses.

KW - Autoreactive

KW - Epitopes

KW - GAD

KW - GAD-alum

KW - Glutamic acid decarboxylase

KW - IL-13

KW - Immunotherapy

KW - T cell receptor

KW - T cells

KW - TCR

KW - Th2

KW - TrialNet

UR - http://www.scopus.com/inward/record.url?scp=85082938550&partnerID=8YFLogxK

U2 - 10.1007/s00125-020-05130-7

DO - 10.1007/s00125-020-05130-7

M3 - Article

AN - SCOPUS:85082938550

SN - 0012-186X

VL - 63

SP - 1186

EP - 1198

JO - Diabetologia

JF - Diabetologia

IS - 6

ER -