Mixed polymeric micelles with glycyrrhizic acid as a delivery system for acute lung injury gene therapy

Abstract

Gene therapy for acute lung injury (ALI), a severe lung inflammation disease, was studied considerably in nowadays. Polymer was generally applied to a vector of non-viral gene delivery which could use for ALI therapy. In this study, polyamidoamine generation 2 dendrimer (PAM) was conjugated with histidine, arginine and cholesterol, known as PAMHRchol. Then, Glycyrrhizic acid (GA), the extraction of licorice root, was combined with PAMHRchol producing mixed micelle complex. PAMHRchol/GA would be reasonable to deliver DNA due to a positive charge of PAM surfaces. Moreover, histidine and arginine enhanced endosomal escape and cellular uptake. Owing to the pharmacological activity of GA, this study expected for alleviating LPS-induced inflammation, synergized with HO-1 therapeutic gene. To evaluate this hypothesis, pDNA/PAMHRchol/GA complex was used as a gene carrier and applied for ALI gene therapy. Firstly, the ratios of the complexes were decided in terms of high transfection efficiency and low toxicity in L2 lung epithelial cells. pDNA/PAMHRchol and pDNA/PAMHRchol/GA complexes had the optimum ratios at 1:9 and 1:9:8 respectively, and the complexes were characterized for micelle formation and stability. Unexpectedly, in the presence of GA, the transfection efficiency was increased, and it could deliver a gene into the various types of cells effectively. Moreover, the complexes reduced LPS-induced inflammatory cytokines in vitro, confirming the synergistic anti-inflammatory effects of PAM and GA. In the ALI animal models, pHO-1/PAMHRchol and pHO-1/PAMHRchol/GA were evaluated via intratracheal administration. It was shown that pHO-1/PAMHRchol/GA reduced pro-inflammatory cytokine in the BAL fluid and lung tissues. According to tissue analysis, PAMHRchol/GA complex delivered HO-1 gene and induced gene expression significantly, and the complex overcame the tissue damage in ALI. In conclusion, GA mixed with polymeric micelles enhanced a gene delivery with anti-inflammatory effect in the lung and could be effective in ALI gene therapy.