Apolipoprotein E deficiency and a mouse model of accelerated liver aging

The liver is the central metabolic organ which regulates several key aspects of lipid metabolism. The liver changes with age leading to an impaired ability to respond to hepatic insults and an increased incidence of liver disease in the elderly. Apolipoprotein E (ApoE) null mice have proved to be a very popular model to study spontaneous atherosclerosis, but recently it has been demonstrated that in ApoE-/- mice liver there are enzymatic and structural alterations, normally linked to the age. The purpose of this study was to consider ApoE-/- mice as a model for oxidative stress induced hepatic disease and to clarify how ApoE inactivation accelerates the aging process and causes liver disease.We used ApoE null mice and control mice at different ages (6 weeks and 15 months). Liver morphological damage as well as proteins involved in oxidative stress and liver ageing were all analyzed.Our study showed that ApoE null mice develop important age-related changes including oxidative stress, pseudocapillarization, increased polyploidy, decreased hepatocyte number and increased nuclear size. Our findings provide evidence that hypercholesterolemic ApoE-/- mice are more likely to develop severe liver injury, suggesting that in addition to vascular disease, increased cholesterol products and oxidative stress may also play a role in accelerating the progression of aging in the liver.