Soluble immune checkpoints associated with disease activity and treatment response in GD and TED

Abstract Context Soluble immune checkpoints play an important role in peripheral tolerance that has seldom been investigated in Graves' disease (GD) and thyroid eye disease (TED). Objective The objective of this work is to examine the alteration of soluble immune checkpoints in GD and TED. Methods We performed a quantitative multiplex analysis of 17 immune checkpoint proteins in serum from 50 GD patients without TED, 28 GD patients with TED, and 40 healthy controls. The association with demographic, serologic, clinical features and 27 cytokines was analyzed. A follow-up was conducted in GD patients without TED. Functional outcomes of sLAG-3 and sGITR were assessed in cell cultures using rh-LAG3, rh-GITR, an antagonistic LAG-3 antibody, and an antagonistic GITR antibody. Results GD Patients with TED had distinct sICP and cytokine profiles compared with GD patients without TED. Active patients with TED exhibited elevation in the levels of sBTLA, sLAG-3, sGITR, sCD80, sCD86, and sPD-L1. Further, GD patients without TED with high sBTLA, sCD27, and sCD40 levels at baseline showed a better improvement in thyrotropin receptor antibody titers after antithyroid drug treatment. Adding recombinant human GITR and LAG-3 to peripheral blood mononuclear cell cultures resulted in increased inflammatory cytokine secretion and decreased anti-inflammatory cytokine secretion. Conclusion The present study uncovers disturbed soluble immune checkpoints and cytokines in GD patients with and without TED and may pave the way for novel immunological screening, allowing for identification of patients with TED at higher risk of developing active disease and patients with GD a better treatment response after antithyroid drug treatment.