Treatment of Bleomycin-induced Pulmonary Fibrosis by Intratracheal Instillation Administration of Ellagic Acid-Loaded...

Idiopathic Pulmonary Fibrosis (IPF) is a rare and serious chronic interstitial lung disease that may endanger the lives of patients. The median survival time of patients with idiopathic pulmonary fibrosis is short, and the mortality rate is higher than that of many types of cancer. At present, pirfenidone (PFD) and nintedanib (NDNB) have been approved by FDA for IPF, but they can only delay the process of pulmonary fibrosis and cannot cure the disease. Therefore, it is urgent to develop other drugs with the effect of improving pulmonary fibrosis. Ellagic acid (EA) can inhibit the Wnt-signaling pathway and has an effect in treating pulmonary fibrosis induced by bleomycin (BLM) in mice. However, its solubility is poor, resulting in its low bioavailability and limited therapeutic benefits, so its clinical application has been limited. Herein, based on the characteristics of nano-drug lung delivery system, chitosan (CS) was selected as the carrier, and ellagic acid-loaded chitosan nanoparticles (EA-CS-NPs) were prepared by ionic gelation method. The EE% and DL% of prepared EA-CS-NPs was 73.73 ± 4.52% and 6.23 ± 1.09%, the particle size was 119.6 ± 5.51 nm (PDI = 0.234 ± 0.017), the zeta potential was 29.833 ± 0.503 mV. The morphology of the nanoparticles was observed by TEM microscope, which was round, uniform dispersion, indicating that the preparation process is stable and feasible. The toxicity experiment showed that EA-CS-NPs maintained 80% cell viability, significantly higher than that of the NDNB group, indicating lower toxicity and better inhibitory effects on TGF-β1-stimulated MLg and NIH-3T3 cells. Wound healing assay results showed that the inhibitory effect of EA-CS-NPs on cell migration was more pronounced than that of EA in the same amount of EA-containing drugs. Drug uptake experiments revealed that EA-CS-NPs significantly enhanced drug uptake in MLg and NIH-3T3 cells. In vivo, Cy7-CS-NPs exhibited higher fluorescence intensity in rat lungs compared to Cy7 solution, indicating better lung retention. The in vivo efficacy test showed that compared with the EA group, EA-CS-NPs could better reduce the area of pulmonary fibrosis and collagen deposition, improve lung function, and have a longer retention time in the lung. In summary, our results revealed that EA-CS-NPs may be a good choice for the treatment of pulmonary fibrosis.