A Predictive Role of Autoantibodies Against the Epitope aa168–183 of ENO1 in the Occurrence of Miscarriage Related to Thyroid Autoimmunity

Abstract

ObjectiveThe aim of the research is to study the association between the serum levels of autoantibodies against one important epitope (168FMILPVGAANFREAMR183, designated as P6) of α-enolase (ENO1-P6Abs) and miscarriage among euthyroid females with thyroid autoimmunity (TAI).MethodsAnti-ENO1-P6 total IgG was investigated in 432 euthyroid women, and its four subclasses were analyzed in 184 euthyroid women. The serum FT4, TSH, TgAb, and TPOAb levels were determined using an electrochemiluminescence immunoassay. The serum ENO1-P6Ab and anti-protein disulfide isomerase A3 autoantibody (PDIA3Ab) levels were determined using an enzyme-linked immunosorbent assay.ResultsThe serum levels of anti-ENO1-P6 total IgG, IgG2, IgG3, and IgG4 were significantly higher in euthyroid TAI females than in non-TAI controls. Additionally, anti-ENO1-P6 total IgG and its 4 subtypes were all markedly higher in euthyroid TAI females with pregnancy loss than those without miscarriage. Moreover, logistic regression analysis showed that highly expressed anti-ENO1-P6 total IgG, IgG1, IgG2, and IgG3 subtypes in the serum were all independent risk factors for euthyroid TAI-related miscarriage, and its IgG1 was also for non-TAI-related abortion. According to the trend test, the prevalence of miscarriage was increased in a titer-dependent manner with the raised levels of serum anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subtypes among euthyroid TAI females. The receiver operating characteristic curve analysis of anti-ENO1-P6 total IgG and IgG1, IgG2, and IgG3 subclass expressions in the serum for miscarriage prediction in euthyroid TAI females exhibited that the total areas under the curves were 0.773 ± 0.041, 0.761 ± 0.053, 0.827 ± 0.043, and 0.760 ± 0.050, respectively (all P <0.0001). Their corresponding optimal cut-off OD450 values were 0.68 (total IgG), 0.26 (IgG1), 0.97 (IgG2), and 0.48 (IgG3), with sensitivities of 70.8, 87.5, 83.3, and 85.4%, and specificities of 70.8, 59.1, 77.3, and 56.8%, respectively. There was an additive interaction between serum anti-ENO1-P6 and anti-PDIA3 total IgGs on the development of miscarriage (RERI = 23.6, AP = 0.79, SI = 5.37).ConclusionThe highly expressed ENO1-P6Abs may be important risk factors for euthyroid TAI-related miscarriage. The serum levels of ENO1-P6Abs may become good predictive markers for pregnancy loss in euthyroid TAI females, especially its IgG2 subclass expression.

Determination of the Predictive Roles and Potentially Pathogenic Antigen Epitopes of α-Enolase Related to the Development of Miscarriage in Females with Autoimmune Thyroiditis

“…The characteristics of the 432 participants from the non-AIT non-miscarriage, non-AIT miscarriage, AIT non-miscarriage, and AIT miscarriage groups were described in our previous study [ 20 ]. There were no significant differences in age, BMI, serum levels of free thyroxine (FT4), and serum ferritin (SF) between the four groups.…”

“…In order to study the role of ENO1Ab in miscarriage, logistic regression analysis (LRA) was performed for those potential risk factors of miscarriage in our participants [ 20 ]. As in our previous study, participants with either a smoking or drinking history were too few to be included in the LRA [ 20 ].…”

“…In order to study the role of ENO1Ab in miscarriage, logistic regression analysis (LRA) was performed for those potential risk factors of miscarriage in our participants [ 20 ]. As in our previous study, participants with either a smoking or drinking history were too few to be included in the LRA [ 20 ]. According to the results of the LRA, serum ENO1Ab levels were found as an independent risk factor in both AIT (OR = 15.295) and non-AIT women (OR = 4.795) ( Table 1 and Table 2 ).…”

“…However, only serum P6Ab exhibited both significantly higher levels in AIT patients with miscarriage than those without pregnancy loss, and significantly higher levels in AIT patients when compared with those of non-AIT women who all suffered from miscarriage. Finally, the serum P6Ab levels were further detected in a total of 432 women with euthyroidism in our other study, which consisted of 48 AIT miscarriage women and matched controls in a 1:2 ratio (96 AIT patients without miscarriage, 96 non-AIT patients with miscarriage, and 192 without miscarriage) [ 20 ]. We found that serum titers of anti-ENO1-P6 total IgG and its four subtypes were not only pronouncedly increased in AIT females compared to non-AIT women, but also significantly higher in AIT females with spontaneous abortion than those without abortion.…”

“…They were all independently associated with the occurrence of miscarriage in AIT patients. ROC showed that the largest AUC was 0.827 ± 0.043 for anti-ENO1-P6 IgG2 [ 20 ]. All these findings suggest that ENO1-P6Ab may be involved in the development of AIT-related miscarriage, and it can be potentially used as a good biomarker for that disorder, especially anti-ENO1-P6 IgG2.…”