Alpha-lipoic acid upregulates the PPARγ/NRF2/GPX4 signal pathway to inhibit ferroptosis in the pathogenesis of unexplained recurrent pregnancy loss

Aim - With unknown etiology and limited treatment options, unexplained recurrent pregnancy loss (URPL) remains a thorny problem. Ferroptosis, a newly identified type of cell death, has been shown to be crucial in the development in reproductive disorders. This study aims to explore the specific mechanism of ferroptosis in URPL and to uncover whether alpha-lipoic acid (ALA) can inhibit ferroptosis, and then exert a protective effect in URPL. Method - The decidua tissues of URPL and control patients who actively terminated pregnancy were collected. The CBA/J x DBA/2 murine models of URPL were established, and were randomly treated with peroxisome proliferator activated receptor gamma (PPAR gamma) agonists (Rosiglitazone) and ALA. The CBA/J x BALB/c murine models of normal pregnancy were intraperitoneally injected with PPAR gamma inhibitors (T0070907). Here, we used reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH)/GSSG, and FeRhoNox-1 analysis to detect the level of ferroptosis. We used quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis to evaluate the mRNA level of PPAR gamma. Besides, western blot and immunofluorescence were utilized to test the expression profile of PPAR gamma/nuclear factor erythroid 2-related factor 2 (NRF2)/glutathione peroxidase 4 (GPX4). Results - In this study, we found that iron deposition was increased in the decidual tissue of patients with URPL. Additionally, the changes in cell morphology, the level of ROS, MDA, GSH, and the expression of ferroptosis marker proteins NRF2/GPX4 confirmed activated ferroptosis in URPL. Besides, bioinformatics analysis combined with experiments confirmed that PPAR gamma was critical in triggering NRF2/GPX4 pathway in URPL. Furthermore, URPL mouse models were established, and the results showed that PPAR gamma/NRF2/GPX4-mediated ferroptosis was also significantly increased, which could be mitigated by ALA treatment. Conclusion - Overall, these findings suggest that ferroptosis may play an important role in URPL, and ALA might be a promising therapeutic drug for improving pregnancy outcomes in URPL via targeting the PPAR gamma/NRF2/GPX4 pathway.