Responders to low-dose ATG induce CD4+ T cell exhaustion in type 1 diabetes
Laura M. Jacobsen, Kirsten Diggins, Lori Blanchfield, James McNichols, Daniel J. Perry, Jason Brant, Xiaoru Dong, Rhonda Bacher, Vivian H. Gersuk, Desmond A. Schatz, Mark A. Atkinson, Clayton E. Mathews, Michael J. Haller, S. Alice Long, Peter S. Linsley, Todd M. Brusko
Laura M. Jacobsen, Kirsten Diggins, Lori Blanchfield, James McNichols, Daniel J. Perry, Jason Brant, Xiaoru Dong, Rhonda Bacher, Vivian H. Gersuk, Desmond A. Schatz, Mark A. Atkinson, Clayton E. Mathews, Michael J. Haller, S. Alice Long, Peter S. Linsley, Todd M. Brusko
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Clinical Research and Public Health Endocrinology Immunology

Responders to low-dose ATG induce CD4+ T cell exhaustion in type 1 diabetes

Abstract

BACKGROUND Low-dose anti–thymocyte globulin (ATG) transiently preserves C-peptide and lowers HbA1c in individuals with recent-onset type 1 diabetes (T1D); however, the mechanisms of action and features of the response remain unclear. Here, we characterized the post hoc immunological outcomes of ATG administration and their potential use as biomarkers of metabolic response to therapy (i.e., improved preservation of endogenous insulin production).METHODS We assessed gene and protein expression, targeted gene methylation, and cytokine concentrations in peripheral blood following treatment with ATG (n = 29), ATG plus granulocyte colony–stimulating factor (ATG/G-CSF, n = 28), or placebo (n = 31).RESULTS Treatment with low-dose ATG preserved regulatory T cells (Tregs), as measured by stable methylation of FOXP3 Treg-specific demethylation region (TSDR) and increased proportions of CD4+FOXP3+ Tregs (P < 0.001) identified by flow cytometry. While treatment effects were consistent across participants, not all maintained C-peptide. Responders exhibited a transient rise in IL-6, IP-10, and TNF-α (P < 0.05 for all) 2 weeks after treatment and a durable CD4+ exhaustion phenotype (increased PD-1+KLRG1+CD57– on CD4+ T cells [P = 0.011] and PD1+CD4+ Temra MFI [P < 0.001] at 12 weeks, following ATG and ATG/G-CSF, respectively). ATG nonresponders displayed higher proportions of senescent T cells (at baseline and after treatment) and increased methylation of EOMES (i.e., less expression of this exhaustion marker).CONCLUSION Altogether in these exploratory analyses, Th1 inflammation-associated serum and CD4+ exhaustion transcript and cellular phenotyping profiles may be useful for identifying signatures of clinical response to ATG in T1D.TRIAL REGISTRATION ClinicalTrials.gov NCT02215200.FUNDING The Leona M. and Harry B. Helmsley Charitable Trust (2019PG-T1D011), the NIH (R01 DK106191 Supplement, K08 DK128628), NIH TrialNet (U01 DK085461), and the NIH NIAID (P01 AI042288).

Authors

Laura M. Jacobsen, Kirsten Diggins, Lori Blanchfield, James McNichols, Daniel J. Perry, Jason Brant, Xiaoru Dong, Rhonda Bacher, Vivian H. Gersuk, Desmond A. Schatz, Mark A. Atkinson, Clayton E. Mathews, Michael J. Haller, S. Alice Long, Peter S. Linsley, Todd M. Brusko

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Figure 4

Differential effect of ATG and ATG/G-CSF on Tregs.

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Differential effect of ATG and ATG/G-CSF on Tregs. Blue lines represent ...
Blue lines represent the ATG arm, green lines the ATG/G-CSF arm, and red lines the placebo arm; solid lines denote responders and dashed lines nonresponders. Panels depict (A) the median percentage methylation of the TSDR region of FOXP3 (n = 255 samples over 3 time points) and (B) the percentage of FOXP3+CD4+ T cells via flow cytometry (n = 279 samples over 4 time points). Treatment effects were assessed via post hoc ANCOVA (*P < 0.05, **P < 0.001). In panel A, there was not a significant difference between ATG-treated participants and placebo- or ATG/G-CSF–treated and placebo at any single time point. However, there was a marked rise in the percentage methylation of the FOXP3 TSDR from baseline to 12 weeks (and baseline to 48 weeks) in those in the ATG/G-CSF arm (P < 0.001 for both).