Dual-Scale Liposomal Assembly Enables Alveolar Macrophage-Targeted Gene Delivery in High-Altitude Pulmonary Edema and Acute Lung Injury.

Inhaled nanocarriers must withstand aerosolization, reach disease-relevant lung cells, and release their cargo into the cytosol, requirements seldom met simultaneously. We introduce a dual-scale, pH-responsive liposomal platform (oLip-RA) that reversibly aggregates into >1 μm clusters at neutral pH to promote size-dependent recognition by alveolar macrophages (AMs), then stepwise disassembles in endo/lysosomes into nanoscale liposomes, enabling endosomal escape and delivery of therapeutics (e.g., RNAs, proteins, antibodies). By relying on size rather than ligands, oLip-RA achieves macrophage targeting without susceptibility to pulmonary surfactant coronas. Mechanistically, clustering distributes aerosol shear across intervesicle contacts, while high-curvature subliposomes resist membrane failure, conferring superior nebulization stability over giant vesicles. Nebulization studies showed that oLip-RA preserves structure and function across two nebulizer types and retains AM tropism. Single-cell lung cytometry confirmed preferential AM uptake in vivo. In a hypoxia-driven high-altitude pulmonary edema (HAPE) model, inhaled oLip-RA reprogrammed AMs from pro-inflammatory M1 to anti-inflammatory M2, thereby restoring endothelial function (increased nitric oxide signaling and decreased permeability), preserving epithelial fluid clearance, and reducing pulmonary edema. As a scope extension, in a streamlined test in a lipopolysaccharide-induced acute lung injury model likewise oLip-RA reduced edema and tracer leakage, supporting its broader applicability while keeping HAPE as the primary focus. Together, these results establish oLip-RA as a nebulization-ready platform that resolves the deposition-to-escape "size paradox" and enables macrophage-targeted gene therapy across hypoxic and endotoxin-induced lung injuries.