The mucus layer and cell membrane are two major barriers against pulmonary siRNA delivery. Commonly used polycationic gene vectors can hardly penetrate the mucus layer due to the adsorption of mucin glycoproteins that trap and destabilize the polyplexes. Herein, guanidinated and fluorinated bifunctional helical polypeptides were developed to synchronizingly overcome these two barriers. The guanidine domain and α-helix facilitated trans-membrane siRNA delivery into macrophages, whereas fluorination of the polypeptides dramatically enhanced the mucus permeation capability by ∼240 folds, because incorporated fluorocarbon segments prevented adsorption of mucin glycoproteins onto polyplexes surfaces. Thus, when delivering TNF-α siRNA intratracheally, the top-performing polypeptide P7F7 provoked highly efficient gene knockdown by ∼96% at 200 μg/kg siRNA and exerted pronounced anti-inflammatory effect against acute lung injury. This study thus provides an effective strategy for transmucosal gene delivery, and it also renders promising utilities for the noninvasive, localized treatment of inflammatory pulmonary diseases.

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.

Herein, recent advances in the synthesis of the water-soluble polypeptides with ordered secondary structures via ring-opening polymerization of NCA/NTA and their biological applications are described.

A series of OEGylated poly(c-benzyl-L-glutamate) with different oligo-ethylene-glycol side-chain length, molecular weight (MW 5 8.4 3 10 3 to 13.5 3 10 4 ) and narrow molecular weight distribution (PDI 5 1.12-1.19) can be readily prepared from triethylamine initiated ring-opening polymerization of OEGylated c-benzyl-L-glutamic acid based N-carboxyanhydride. FTIR analysis revealed that the polymers adopted a-helical conformation in the solid-state. While they showed poor solubility in water, they exhibited a reversible upper critical solution temperature (UCST)-type phase behavior in various alcoholic organic solvents (i.e., methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, and isopropanol). Variable-temperature UV-vis analysis revealed that the UCST-type transition temperatures (T pt s) of the resulting polymers were highly dependent on the type of solvent, polymer concentration, side-and main-chain length.

Dysregulated inflammation and failure in resolution account for the incidence and deterioration of rheumatoid arthritis (RA). IL‐4 and miR‐21 possess complementary functions in inhibiting inflammation and fostering resolution. Thus, inflammation‐instructed nanocomplexes (NCs) are herein developed to mediate hierarchical co‐delivery of miR‐21 and IL‐4 to orchestrate the osteoimmune microenvironment against RA. The NCs comprise a cationic inner core assembled from the membrane‐penetrating, helical polypeptide (PG) and miR‐21, an outer layer based on the acid‐responsive, charge reversal polymer (PLL‐CA), and surface‐adsorbed IL‐4. The negatively charged NCs enable prolonged blood circulation after systemic administration, and thus passively accumulate in the inflamed joint. In the slightly acidic microenvironment of inflamed synovium, PLL‐CA transforms from negative to positive, which sheds off to liberate IL‐4 extracellularly and facilitate the intracellular delivery of the PG/miR‐21 core into macrophages. Thus, the anti‐inflammatory miR‐21 cooperates with the proresolving IL‐4 to attenuate inflammation via NF‐κB inhibition, promote macrophage polarization to M2a/M2c phenotypes, propel resolution, and promote tissue repair against Zymosan A‐induced arthritis. This study provides an effective strategy toward the programmed delivery of drug/gene cargoes at different extracellular/intracellular locations, and the combined mechanism of anti‐inflammation and proresolution renders insights into the treatment of inflammatory diseases.