Sulfamethoxazole increases the risk of preeclampsia through PSMB6: A comprehensive multi-omics and experimental validation study.

BACKGROUND: Environmental and dietary exposure to sulfamethoxazole (SMX) has been detected in pregnant populations, but its impact on preeclampsia (PE)-related placental pathology-particularly through non-therapeutic chronic exposure-remains poorly understood. METHODS: We assessed the effects of maternal SMX exposure on placental structure in pregnant mice. Placental transcriptomic data and Mendelian randomisation (MR) analysis were integrated to identify candidate targets. Molecular docking, molecular dynamics simulations, cellular thermal shift assay (CETSA), and microscale thermophoresis (MST) were used to validate SMX-target interactions. Loss-of-function and SMX-exposure experiments in trophoblast cells were performed to evaluate mitochondrial respiration and oxidative phosphorylation (OXPHOS). RESULTS: Maternal SMX exposure disrupted the placental labyrinth, reduced the labyrinth/junctional zone ratio, and enlarged maternal blood sinuses. Integrative transcriptomic and MR analyses identified nine candidate targets, among which PSMB6 was downregulated in PE placentas and genetically associated with reduced PE risk (MR OR = 0.78). Docking and molecular dynamics simulations suggested stable SMX-PSMB6 binding, which CETSA and MST further supported. Single-cell and enrichment analyses linked PSMB6 to mitochondrial energy metabolism and OXPHOS in trophoblast cells. Functionally, PSMB6 knockdown impaired mitochondrial respiration and downregulated OXPHOS-related genes, while SMX exposure produced a similar mitochondrial dysfunction phenotype. CONCLUSION: These findings suggest that SMX exposure may contribute to PE-like placental abnormalities by affecting PSMB6, a protein homeostasis-related molecule, and impairing mitochondrial energy metabolism in trophoblasts, providing mechanistic insight into the placental effects of non-therapeutic SMX exposure.