Microcirculatory disturbances and cellular changes during progression of hepatic steatosis to liver tumors.

Non-alcoholic fatty liver disease is closely associated with metabolic syndrome and comprises a pathological spectrum of liver disease ranging from steatosis to steatohepatitis and can progress to fibrosis/cirrhosis and hepatocellular carcinoma. In 2013, a mouse model was described that mimics non-alcoholic fatty liver disease progression from steatohepatitis to tumors in a short time span and with high incidence. As microcirculatory disturbances play a crucial role in liver disease, the suitability of the steatosis-inflammation-tumor model for microcirculatory studies was assessed. Herein, we present a comprehensive view on morphological, microvascular, cellular, and functional aspects of non-alcoholic fatty liver disease progression in the steatosis-inflammation-tumor model using intravital microscopy, biochemical, and histological techniques. Mice develop steatohepatitis, mild fibrosis, and liver tumors at ages of 6, 12, and 20 weeks, respectively. Non-alcoholic fatty liver disease progression was accompanied by several general aspects of disease severity like increasing liver/body weight index, non-alcoholic fatty liver disease activity score, and hepatocellular apoptosis. Intravital microscopic analysis revealed significant changes in hepatic microcirculation with increasing structural alterations, elevated leukocyte adherence, and impaired nutritive perfusion. Non-alcoholic fatty liver disease was further characterized by a lower sinusoidal density with a striking rise at 20 weeks. The characteristic microcirculatory changes make the model a convenient tool for analysis of microcirculation during progression from steatosis to liver tumor. Impact statement Significant alterations of microcirculation contribute to progression of NAFLD, a chronic liver disease with increasing medical and socio-economic impact. Characterization of microcirculation in a NAFLD model reflecting all relevant stages of disease progression was still missing. Thus, we evaluated microcirculatory and cellular changes in a steatosis-inflammation-tumor model using in vivo microscopy. Analyses revealed increasing structural alterations, elevated leukocyte-endothelial interaction, and impaired nutritive perfusion. Thus, this model is suitable for further studies investigating therapeutic approaches targeting these progressive microcirculatory disturbances.