CY7 is an ionizable lipid engineered for localized pulmonary mRNA delivery. Its structure combines a cyclohexane-based core, a 4-dimethylaminopiperidine ionizable headgroup, two ester linkers, and four extended hydrophobic branches. In LNPs formulated with cholesterol, DSPC, and DMG-PEG, CY7 produced substantially higher local luciferase expression and lung-to-liver selectivity than SM-102 following intratracheal administration. CY7 LNPs also enhanced functional mRNA expression in pulmonary neutrophils, endothelial and epithelial cells, as well as dendritic and B cells in lung-draining lymph nodes. When used to deliver PcrV and OprF-I mRNAs, pulmonary CY7 LNP vaccination generated rapid antigen-independent innate protection followed by durable antigen-specific humoral, mucosal, and cellular immunity. In mouse models, it reduced bacterial burden and improved survival following challenge with laboratory and carbapenem-resistant Pseudomonas aeruginosa. CY7 remains a preclinical research lipid requiring further pharmacokinetic, repeat-dose, and translational safety evaluation.
