NAFLD starts with over-nutrition, imbalance between energy input and output for which the roles of genetic predisposition and environmental factors (diet, physical activity) are being redefined. Regulation of energy balance operates at both central nervous system and peripheral Selleckchem Daporinad sites, including adipose and liver. For example, the endocannabinoid
system could potentially be modulated to provide effective pharmacotherapy of NAFLD. The more profound the metabolic abnormalities complicating over-nutrition (glucose intolerance, hypoadiponectinemia, metabolic syndrome), the more likely is NAFLD to take on its progressive guise of non-alcoholic steatohepatitis (NASH). Interactions between steatosis and insulin resistance, visceral adipose Hydroxychloroquine expansion and subcutaneous adipose failure (with insulin resistance, inflammation and hypoadiponectinemia) trigger amplifying mechanisms for liver disease. Thus, transition from simple steatosis to NASH could be explained by unmitigated hepatic lipid partitioning with failure of local adaptive mechanisms leading to lipotoxicity. In part one of this review, we discuss newer concepts of appetite and metabolic regulation, bodily lipid distribution, hepatic lipid turnover, insulin resistance and adipose failure affecting adiponectin secretion. We review evidence
that NASH only occurs when over-nutrition is complicated by insulin resistance and a highly disordered metabolic milieu, the same ‘metabolic movers’ that MCE promote type 2 diabetes and atheromatous cardiovascular disease. The net effect is accumulation of lipid molecules in the liver. Which lipids and how they cause injury, inflammation and fibrosis will be discussed in part two. It is more than 30 years since alcoholic hepatitis-like lesions were
recognized among over-weight or diabetic non-drinkers, for which Ludwig, in 1980, coined the term non-alcoholic steatohepatitis (NASH).1 Interest in this disorder has burgeoned recently.2–6 A decade ago it was known that fatty liver had many causes,2 and the present convention is to label cases with definable single etiologies as such, e.g. drug-induced steatohepatitis, fatty liver associated with parenteral nutrition, rather than ‘secondary NASH’. The term non-alcoholic fatty liver disease (NAFLD) should be reserved for those cases in which there is not one single cause. The latter are nearly always associated with overweight, particularly central obesity and insulin resistance, and often glucose intolerance/type 2 diabetes (T2D), dyslipidemia, hypertension and other features of the metabolic syndrome.2–5 For this reason, we proposed the term metabolic steatohepatitis,2 but the simpler term NAFLD infers an inextricable relationship between this type of fatty liver and the metabolic complications of over-nutrition.