Inhibition of Mitochondrial Fatty Acid Oxidation Contributes to Development of Nonalcoholic Fatty Liver Disease Induced by Environmental Cadmium Exposure

Cadmium (Cd) is one of the most prevalent toxic metal pollutants widely distributed in water and soil environments. Epidemiological studies have shown that exposure to Cd is implicated in the prevalence of nonalcoholic fatty liver disease (NAFLD) in middle-aged human population, but biological evidence is lacking and its toxicological mechanism remains unclear for the disease predisposition from environmental Cd exposure. In this study, we established a chronic Cd-exposure mouse model mimicking the liver Cd deposition in middle-aged human population to determine whether the environmental Cd exposure can induce NAFLD. Results showed that hepatic Cd burden at levels of 0.95 and 6.04 μg/g wet weight resulting from 20-week Cd exposure at different doses induced NAFLD and nonalcoholic steatohepatitis-like phenotypes in mice, respectively. The Cd exposure caused marked hepatic mitochondrial dysfunction and fatty acid oxidation deficiency, along with significant suppression of sirtuin 1 (SIRT1) signaling pathway in the liver. In vitro study confirmed that Cd evidently inhibited the mitochondrial fatty acid oxidation in hepatocytes and that SIRT1 signaling was potentially involved in the process. Our findings suggest that exposure to environmental Cd is a tangible risk factor for NAFLD, and the induced public health risks deserve greater attention.