Effects of hyperhomocysteinemia on placental morphology and function

Hyperhomocysteinemia (HHcy), characterized by elevated homocysteine levels, is associated with adverse pregnancy outcomes, though its mechanistic link to placental dysfunction remains unclear. This study aimed to explore how HHcy disrupts placental development to identify conserved molecular mechanisms related to adverse pregnancy outcomes.

We develop murine HHcy model using a high-methionine diet and observe placental and fetal developmental outcome at key pregnancy times (E7.5, E10.5, E13.5). Structural and functional anomalies were detected histopathologically and molecularly to examine potential placental pathology. Expression profiles in placental tissues were determined by transcriptome profiling to describe dysregulated pathways. Expression and activity of lysosomal-autophagy were examined by qRT-PCR, western blotting, and transmission electron microscopy. Clinical validation was performed using placental samples from spontaneous abortion (SA) patients with HHcy and without HHcy and matched controls.

HHcy-exposed mice exhibited significant reductions in embryo implantation rates and fetal viability, accompanied by impaired placental growth and structural disorganization. Histological analysis revealed atrophy of the ectoplacental cone, dilation of intervillous spaces, and diminished labyrinthine/junctional zones. Transcriptomic data highlighted enrichment of lysosomal and inflammatory pathways, corroborated by molecular evidence of lysosomal overload, suppressed autophagy-related gene expression and dysregulated autophagic flux. Placental samples from SA patients with HHcy mirrored these molecular alterations.

Our findings suggest that HHcy disrupts placental homeostasis, impairs lysosomal function, and triggers maladaptive autophagy, leading to adverse pregnancy outcomes. The conserved pathways suggest targeting the lysosomal - autophagic axis might treat HHcy - related pregnancy problems.