Reparative Efficacy of Liposome-Encapsulated Oleanolic Acid against Liver Inflammation Induced by Fine Ambient Particulate Matter and Alcohol in Mice

Airborne fine particulate matter (PM2.5) is a severe problem and is associated with health issues including liver diseases. Workers performing manual labor tend to be alcohol consumers during work, where they are also exposed to PM2.5. Long-term PM2.5 exposure can increase oxidative stress, leading to inflammation. Whether long-term exposure to air pollution and alcohol synergistically increases liver fibrosis risk warrants investigation. Oleanolic acid (OA)—a triterpenoid—has antioxidant and anti-inflammatory activities, but its low water solubility and cytotoxicity impair its potential applications. In this study, we fabricated liposomal OA nanoparticles (Lipo-OAs); then, we evaluated the anti-inflammatory effect on exposed cells and the ameliorative effect of Lipo-OAs on PM2.5 and alcohol-induced liver fibrosis in mice. The half maximal inhibitory concentration of PM2.5 for hepatic stellate cells was 900 μg/mL; at a concentration of ≥600 μg/mL, PM2.5 significantly increased interleukin-6 and tumor necrosis factor-α production. OA encapsulation in Lipo-OAs, 353 ± 140 nm in diameter with 79% encapsulation efficiency, significantly reduced OA cytotoxicity. Lipo-OAs treatment significantly reduced alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltransferase levels; histologically, it alleviated steatosis and improved Ishak’s modified HAI score. In conclusion, Lipo-OAs have potential anti-inflammatory and reparative effects for PM2.5 and alcohol-induced liver injury treatment.