Backgroud:
Autoimmune thyroid diseases (AITD) are the most common organ specific autoimmune disorders. The reduction of serum dipeptidyl peptidase-IV (sDPPIV) levels have been reported in patients with autoimmune diseases. Few studies have analyzed the association between sDPPIV levels and AITD, especially in Graves’ disease (GD), Graves’ ophthalmopathy (GO) patients. So the aim of this study was to evaluate the association between sDPP-IV levels and 3 types of AITD, that is Graves’ disease (GD), Graves’ ophthalmopathy (GO), Hashimoto’s thyroiditis (HT).
Methods
65 newly diagnosed GD ,22 GO, 27 HT patients and 30 healthy individuals were recruited for this study. Clinical characteristics and thyroid function data were collected for all participants. sDPP-IV was measured by enzyme-linked immunosorbent assay.
Results
Compared with the controls, GD patients and GO patients had significantly lower sDPP-IV levels(662.2 ± 38.81 and 438.4 ± 31.78 vs.786.3 ± 46.95, P = 0.01 or P < 0.001). It was also found that in GO individuals, sDPP-IV was lower than in GD subjects(P = 0.002). The lower the sDPP-IV level is, the higher the risk for developing GD or GD will be. In addition, sDPP-IV levels have negative association with the antithyroid peroxidase antibody(TGab)(r =-0.20, p = 0.02) and antithyroglobulin antibody(TPOab)(r =-0.19, p = 0.03). But there was no significant relationship between thyroid hormone and sDPP-IV levels.GO parients were groups by proptosis with and without muscle thicken,the sDPP-IV levels in proptosis with muscle thicken were lower than proptosis without muscle thicken(P < 0.05).Logistic regression analysis showed that sDPP4 were negatively correlated with GO and GD.
Conclusions
Take together, the present study showed for the first time that sDPP-IV concentrations are aberrant in GD and GO patients and that the reduced sDPP-IV expression may be involved in the progression of GO and GD diseases.