Reciprocal Translation Between Pathophysiology and Practice in Health and Disease: Chapter 8 - The gut/liver axis, inflammation, and the pathogenesis of metabolic syndrome

Any extra-intestinal chronic disease or inflammation is a risk factor for the development of non-alcoholic fatty liver disease (NAFLD) and the metabolic syndrome (MetS). Similarly, anatomical, functional, or inflammatory intestinal disease increases the risk of liver disease. Increasing evidence suggests that the gut microbiota play an important role, not only in normal physiology but also in a number of disease states, including obesity, non-alcoholic steatosis hepatis (NASH) and MetS, undernutrition and changes in mood and behavior. Any stress or situation of growth requires upregulation of the activity of the liver to support an adaptive host response. Fat deposition is common in these conditions (NAFLD) and may play a supportive, rather than a damaging role. When mild NAFLD develops in situations of stress (trauma, infection, burns) or increased synthesis of biomass (pregnancy, lactation, puberty, cancer), it does so without clear damage. Storing fat in hepatocytes may support upregulation of their metabolic activity including local delivery of fatty acids as fuel for oxidation and for supporting the beneficial response of intermediary metabolism to stressful events and growth of biomass.