Uncovering Perturbed Molecular Pathways and Potential Biomarkers in Recurrent Pregnancy Loss Using a Systems Biology Approach

Miscarriages affect up to 20% of recognized pregnancies and potentially 50-70% of all conceptions. Recurrent pregnancy loss (RPL) affects 1-5% of recognized pregnancies and involves the loss of two or more consecutive pregnancies before 20 weeks. RPL's causes and molecular pathways remain poorly understood, resulting in a lack of reliable screening tools or effective preventive treatments. To identify the molecular pathways involved in RPL, we employed a hypothesis-free systems biology approach. We collected placental samples from 8 patients with RPL and 8 age-matched controls at 8-12 weeks of gestation, analyzed them using microarray, and performed next-generation proteomics study on blood samples (n=16) obtained during surgery. We identified 1,537 differentially expressed genes, notably including downregulated placenta-specific (n=113, OR: 31.8, p=4.4*10-88) and villous trophoblast differentiation-related (n=398, OR: 3.8, p=5.610-80) genes, indicating impaired trophoblastic functions. We observed an enrichment of immune-associated genes, including upregulated proinflammatory genes and downregulated anti-inflammatory genes, and enriched pathways related to graft rejection and autoimmune processes. We identified perturbed gene modules and validated transcriptomic results for 10 genes using qRT-PCR. We also found decreased placental protein products in maternal blood proteome that mirrored placental gene expression changes, serving as potential biomarkers for RPL. Our study not only contributes to a better understanding of RPL but also identifies potential target drug molecules and biomarkers for RPL, offering hope for more effective preventive treatments in the future. Despite these promising results, further validation in larger clinical studies is necessary to confirm the potential of our findings.