Unveiling the link: anti-protein disulfide isomerase A3 autoantibody expression and polycystic ovary syndrome risk in euthyroid autoimmune thyroiditis women

Background: Polycystic ovary syndrome (PCOS) is a common complication of autoimmune thyroiditis (AIT) in women, but the underlying mechanism remains unclear. Protein disulfide isomerase A3 (PDIA3) is a ubiquitous protein. We have reported that PDIA3 autoantibody (PDIA3Ab) production results from autoimmune responses against thyrocytes, resulting in its high expression in euthyroid AIT patients. This study aimed to explore potential correlations between PDIA3Ab expression and concurrent PCOS in euthyroid AIT women.

Methods: This is a single-center cross-sectional study. All participants, who visited the First Hospital of China Medical University from April 2023 to May 2024, were assigned to four groups according to AIT and PCOS diagnostic criteria. The PDIA3Ab levels of total IgG and IgG subclasses were detected using ELISA.

Results: From highest to lowest, PDIA3Ab total serum IgG levels were categorized as follows: AIT-PCOS group > AIT-non-PCOS group > non-AIT-PCOS group > non-AIT-non-PCOS group Significant differences were observed between each pair of groups, except for the non-AIT-PCOS and non-AIT-non-PCOS groups. Further analysis of the subclasses of PDIA3Ab revealed that serum IgG1 levels in the AIT-PCOS and AIT-non-PCOS groups were significantly higher than those in the non-AIT-PCOS and non-AIT-non-PCOS groups. In addition, the AIT-PCOS group had significantly higher serum IgG3 levels than the other three groups. Binary logistic regression analysis revealed that the PDIA3Ab total IgG level was an independent risk factor for concurrent PCOS in euthyroid AIT women (Q4 vs. Q1: OR, 95%CI = 5.082, 1.348-19.16). Furthermore, a trend test demonstrated a titer-dependent increase in PCOS prevalence among AIT women as the PDIA3Ab total IgG level increased.

Conclusions: The expression of serum PDIA3Ab may indicate an increased risk of PCOS in euthyroid AIT women and could potentially serve as new targets for markers or immune intervention.