Maternal Gut Microbiota Regulates Neonatal Retinal Angiogenesis Through Lactational Metabolic Signalling

Early-life vascular development is a tightly regulated process that influences organ maturation and long-term cardiometabolic and neurovascular health. While the maternal microbiome is increasingly recognised as a determinant of neonatal immune, metabolic, and neurodevelopmental programming, its role in developmental angiogenesis remains poorly defined. Here, we investigated whether maternal gut microbiota regulates neonatal retinal vascular development through maternally derived metabolic signals. Using antibiotic-induced dysbiosis with a broad-spectrum antibiotic cocktail consisting of vancomycin, neomycin, metronidazole, amphotericin B, and ampicillin (VNMAA), together with germ-free animals, we assessed retinal angiogenesis at postnatal day 6 (P6) and P12. Maternal microbiome depletion significantly delayed retinal vascular extension at P6 and produced persistent abnormalities in P12 retinal vascular architecture, including reduced deep plexus vascular density, altered descending branch density, and reduced branching complexity after normalisation to vessel density. Whole-genome shotgun sequencing demonstrated pronounced remodelling of the maternal caecal microbiome following antibiotic treatment and reciprocal faecal microbiota transplantation (FMT), whereas P12 pup caecal communities were comparatively limited and did not mirror the dramatic restructuring observed in dams. Restoration of the maternal microbiome by FMT rescued neonatal vascular defects, supporting a causal role for maternal microbial state. Untargeted LC-MS metabolomics of maternal milk identified glycerophospholipid metabolism as a prominent microbiome-sensitive pathway. Choline and related lipid metabolites were prioritised as candidate mediators because of their position within this pathway and their biological relevance to membrane metabolism and endothelial function. In vitro endothelial assays demonstrated that choline modulates endothelial viability and promotes tubule formation. Together, these findings identify a maternal microbiota-milk metabolite-vascular axis regulating neonatal retinal angiogenesis and suggest that lactational metabolic signalling may represent an important mechanism through which maternal microbial ecology shapes offspring vascular development.