The serum concentration and activity of DPP4 is positively related with the severity of hyperthyroidism in patients with Graves’ disease

OBJECTIVE: Graves’ disease (GD) is an organ-specific autoimmune disease. The production of anti-thyrotropin receptor antibodies (TRAb) is associated with a loss of immune tolerance. Dipeptidyl peptidase-4 (DPP-4) is expressed on multiple immune cells. This study aimed to investigate the relationship between serum concentration/activity of DPP4 and the severity of hyperthyroidism in GD patients. METHODS: A total of 82 newly diagnosed drug-naive patients with GD hyperthyroidism, 20 patients with non-autoimmune thyrotoxicosis and 122 age- and sex- matched healthy controls were enrolled. The clinical parameters and serum concentration and activity of DPP4 were measured. RESULTS: The GD group had increased serum concentration and activity of DPP4 than the healthy controls and patients with non-autoimmune thyrotoxicosis, while no significant difference was observed in the latter two groups. Multivariate linear regression indicated that the serum concentration/activity of DPP4 were positively associated with FT3, FT4 and TRAb levels in the GD patients. And the positive association between serum concentration/activity of DPP4 and TRAb was remained even after adjustment for confounding factors (all p < 0.05). CONCLUSIONS: The GD patients had significantly increased serum concentration/activity of DPP4. And the serum concentration/activity of DPP4 was positively associated with the severity of hyperthyroidism in GD patients. KEY MESSAGES: The activity and concentration of DPP4 in patients with Graves’ disease were higher than those in healthy controls. There was a significant positive correlation between serum DPP4 concentration and TRAb levels in patients with Graves’ disease. In patients with Graves ‘disease, serum DPP4 activity was positively correlated with TRAb levels.