Pulmonary delivery of anti-inflammatory siRNA holds great potential in mitigating the cytokine storm during severe pneumonia. However, commonly utilized polycationic siRNA delivery vehicles can hardly penetrate the mucus barrier, thus greatly hurdling their therapeutic efficacy. Herein, TNF-α siRNA (siTNF-α) delivery nanocomplexes (NCs) are engineered with mucus/cytomembrane dual-penetration capabilities, realized via surfacecoating of NCs with RC, an inflammation-sheddable, charge-reversal pro-peptide of RAGE-binding peptide (RBP). RC-coated dendritic poly-Llysine/siTNF-α (DsT) NCs possess negative surface charges, and can thus efficiently penetrate the mucus layer after intratracheal administration. In the inflamed alveolar space with mild acidity, RC recovers to the cationic RBP and shed off, re-exposing the DsT NCs that efficiently transfect the alveolar macrophages and provokes TNF-α silencing. Thus, siTNF-α and RBP cooperatively alleviate the uncontrolled inflammation during acute lung injury. This study renders a unique approach for mediating trans-mucus nucleic acid delivery, and will find promising utilities for the treatment of severe pneumonia.

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Acute lung injury (ALI) is a lung inflammatory disease for which pulmonary delivery of drug and gene could be a useful strategy. In this study, cholesterol-conjugated polyamidoamine (PAM-Chol) was synthesized and characterized as a carrier for combined delivery of anti-inflammatory gene and drug into the lungs by inhalation. The PAM-Chol formed self-assembled micelles in an aqueous solution with a critical micelle concentration of 0.22 mg ml-1. An in vitro transfection assay to L2 lung epithelial cells showed that the PAM-Chol micelle had higher transfection efficiency than lipofectamine and polyethylenimine (25 kDa, PEI25k). As the anti-inflammatory drug, resveratrol was loaded into the cores of the PAM-Chol micelles using the oil-in-water emulsion/solvent evaporation method. In lipopolysaccharide (LPS)-activated macrophage cells, resveratrol-loaded PAM-Chol (PAM-Chol/Res) reduced pro-inflammatory cytokines, confirming the anti-inflammatory effects of resveratrol. In in vitro transfection assays to L2 cells, the PAM-Chol/Res micelles had transfection efficiency similar to that of PAM-Chol. The delivery of resveratrol or the heme oxygenase-1 gene (pHO-1) by inhalation was evaluated in an ALI animal model. Resveratrol delivery using the PAM-Chol/Res micelles inhibited the nuclear translocation of nuclear factor-κB (NF-κB) and reduced pro-inflammatory cytokines in the lungs. pHO-1 delivery using PAM-Chol induced HO-1 expression and reduced pro-inflammatory cytokines. However, the highest anti-inflammatory effects were obtained with combined delivery of pHO-1 and resveratrol using the pHO-1/PAM-Chol/Res complex, as demonstrated in cytokine assays and immunohistochemical studies. Therefore, the PAM-Chol micelle is an efficient carrier of resveratrol and pHO-1 into the lungs and could be useful for the treatment of ALI by inhalation.