Bacterial-Derived Signals Selectively Remodel Glycosaminoglycan Biosynthetic Pathways in Reconstructed Human Corneal Epithelium

Proteoglycans (PGs) and their glycosaminoglycan (GAG) chains play key roles in corneal epithelial physiology and host–microbe interactions. Although bacterial exposure has been shown to alter PG and GAG biosynthesis, the contribution of specific bacterial-derived signals remains unclear. In this study, reconstructed human corneal epithelia (QobuR) were exposed to bacterial extracellular vesicles (BEVs) from Pseudomonas aeruginosa and Staphylococcus epidermidis, as well as to lipopolysaccharide, peptidoglycan, and lipoteichoic acid. The expression of 72 genes involved in PG and GAG biosynthesis and remodeling was analyzed by quantitative real-time PCR. Only 22 genes showed significant transcriptional alterations, indicating a highly selective response. Most changes affected enzymes involved in the generation of heparan sulfate (HS) and chondroitin sulfate (CS) fine structure, particularly sulfotransferases. Notably, HS3ST4 and HS3ST5 were consistently upregulated under all experimental conditions, suggesting that modulation of HS 3-O-sulfation represents a conserved corneal epithelial response to bacterial-derived stimuli. Whereas microbial-associated molecular patterns induced broader transcriptional responses, BEVs elicited more restricted and species-dependent effects. Overall, these findings demonstrate that bacterial-derived signals selectively remodel GAG biosynthetic pathways and provide new insights into the molecular mechanisms underlying host–microbe interactions at the ocular surface.