Inflammation-responsive hierarchical delivery of anti-inflammatory siRNA and peptide alleviates cytokine storm in pneumonia

Abstract

Pulmonary delivery of anti-inflammatory siRNA holds great potential for the management of severe pneumonia. However, conventional siRNA carriers, primarily cationic polymers, struggle to penetrate the mucus barrier, resulting in limited transfection efficiency. Herein, nanocomplexes (NCs) capable of penetrating both the mucus and cytomembrane barriers were developed to deliver TNF-α siRNA (siTNF-α) for effective pneumonia management. To construct the NCs, membrane-penetrating polypeptide (DPP) first condensed siTNF-α and formed a cationic inner core, which was further coated with a charge-reversal polymer (PD) followed by the adsorption of a RAGE-binding peptide (RBP) via electrostatic interactions. The resulting RDDsT NCs exhibited negatively charged surfaces and thus enabled efficient mucus layer penetration after intratracheal administration in lipopolysaccharide (LPS)-induced acute lung injury (ALI) mice. In the slightly acidic microenvironment of inflamed alveolar space, PD underwent charge reversal from negatively charged to positively charged, shedding off to facilitate the intracellular delivery of the DPP/siTNF-α core into alveolar macrophages. Meanwhile, the liberated RBP blocked RAGE–ligand interactions, further down-regulating pro-inflammatory factors. Consequently, the cooperative action of siTNF-α and RBP alleviated inflammation and propelled the recovery of pulmonary functions. This study renders an enlightened strategy to overcome the mucus/cytomembrane barrier against pulmonary siRNA delivery, and holds profound potential for gene/peptide co-therapy against pneumonia.