Pulmonary Delivery of siRNA Anti-TNFα-loaded Lipid Nanoparticles for Rapid Recovery in Murine Acute Lung Injury

This study investigates the potential of pulmonary delivery of siRNA as an emergency therapy for acute lung injury (ALI). To obtain a quick anti-inflammatory response, TNF-α, a critical pro-inflammatory cytokine, is knocked down for its early involvement in inflammatory responses. Therefore, TNF-α siRNA-lipid nanoparticles (LNPs) are designed and characterized for cellular uptake in lipopolysaccharide (LPS)-activated RAW264.7 murine macrophages, primary alveolar macrophages, and neutrophils from a murine ALI model. Intracellular trafficking and siRNA cytoplasmic release are evaluated in untreated and LPS-activated RAW264.7 cells. LPS-activated cells exhibit a fast and strong uptake of LNPs, including in primary cells. In RAW264.7 cells, significant endosomal escape and siRNA cytoplasmic release are observed after 16 h. In vitro efficacy studies reveal consistent TNF-α inhibition across pre-, co-, and post-incubation protocols, confirming the versatility of siRNA-LNPs in preventive or curative conditions. After intratracheal administration of TNF-α siRNA-LNPs in a murine ALI model, the distribution of LNPs demonstrates an accumulation in immune cells, including macrophages and neutrophils, reducing TNF-α and IL-6 levels, indicating a rapid anti-inflammatory effect. This work underscores the efficacy of TNF-α siRNA-LNPs in treating lung inflammatory diseases like ALI and highlights the importance of optimizing LNP distribution and delivery timing to enhance therapeutic outcomes.