Discovery of protein lactylation-associated biomarkers and their potential pathogenic mechanisms in recurrent spontaneous abortion.

Protein lactylation plays a critical regulatory role in various human diseases; however, its function in recurrent spontaneous abortion (RSA) remains unclear. In this study, we integrated scRNA-seq (GSE214607), bulk RNA-seq (GSE26787 and GSE165004) datasets, and lactylation-related gene sets, and applied multiple machine learning methods to identify four lactylation-associated hub genes (HNRNPU, PTMA, CALD1, and S100A11). Immune infiltration analysis based on these genes revealed immune dysregulation in RSA, characterized by decreased expression of immunoregulatory cell-related genes and increased expression of monocyte-associated genes. Clustering analysis identified two molecular subtypes enriched in pathways related to cell cycle and chromosomal maintenance, and immune activation and metabolic dysfunction, respectively. Functional assays demonstrated that elevated lactate levels promoted S100A11 expression, inhibited trophoblast proliferation and invasion, reduced cellular sensitivity to apoptosis, and enhanced the expression of the anti-inflammatory cytokines IL-10 and TGF-β. Mechanistically, S100A11 activated the p38 MAPK-TGF-β1-SMAD-IL-10 signaling pathway to potentiate anti-inflammatory responses. Collectively, these findings suggest that lactate-mediated metabolic reprogramming regulates immune and trophoblasts functions via S100A11, contributing to RSA pathogenesis.