Distinct pattern of peripheral lymphocyte subsets in Graves’ disease with persistency of anti-TSHR autoantibodies

Abstract

Background: Graves’ disease (GD) is characterized by the production of autoantibodies against the TSHR (TRAbs). With long-term treatment, serum concentrations of TRAbs decline but in some patients, despite being clinically stable, TRAbs persist for many years.

Objective: To investigate whether GD patients with persistence of TRAbs constitute a subset of patients that could be identified by phenotypic analysis of circulating lymphocytes, suggesting disease heterogeneity.

Materials and methods: Peripheral blood lymphocytes (including naïve, memory and effector T and B cells, Th17, regulatory T cells (Treg), recent thymic emigrants (RTEs) and double positive CD4⁺CD8⁺ (DP) cells) were analysed by flow cytometry in a cross-sectional study in 25 clinically stable GD patients, five patients at onset of GD disease and 40 healthy donors (HDs).

Results: GD patients with persistence of TRAbs showed a lower percentage of Treg and lower absolute numbers of central and effector memory CD8⁺ T cells than HD. No differences in RTEs were found in peripheral blood from GD patients compared to HD. Stable GD patients had higher percentage of DP cells of effector phenotype than HD.

Conclusions: Using extensive phenotypic analysis of lymphocyte subpopulations, it is possible to detect changes that help to identify patients with persistent TSHR antibodies and may contribute to understand why the autoimmune response is maintained.

Keywords:

• Graves’ disease
• lymphocyte subpopulations
• RTEs
• CD4⁺CD8⁺
• effector memory CD8
• TRAb

Acknowledgements

This work has been supported by positive discussion through ENTIRE network (BM0907; www.entire-net.eu). We thank Dr. Roger Colobran and Dra Paula Correa for helping in the procurement of the thymus tissue. We also thank Amanda Rus and Aroa Pardell for technical assistance. The authors are members of a consolidated group (2017 SGR 103) as recognized by the Agency for Management of University and Research Grants (AGAUR) of the Generalitat of Catalonia. This work was supported in part by project 14/00848 of the Instituto Carlos III (RPB).

Disclosure statement

The authors report no conflict of interest.

Authors’ contributions

ATS designed the research, performed most of the experiments, analyzed and interpreted the results, and drafted the manuscript; BS participated in the design of the study, interpretation of data and helped in writing the manuscript. BQS participated in the interpretation of data and helped in writing the manuscript. MAF participated in the design and analysis of flow cytometry experiments. AEC provided HD samples; BS and MPD provided patient samples. MPD and RPB participated in the design and analysis of the study and revised the manuscript. EMC conceptualized and designed the study, supervised the research and revised the manuscript; and all authors commented on the manuscript.