Hepatic Energy Fluxes in NASH and NAS Patients

Diseases along the nonalcoholic fatty liver disease spectrum, which are tightly coupled to the obesity epidemic, are soon to become the commonest indication for liver transplantation in the United States. Bariatric surgery shows great promise in the treatment of these diseases. The studies proposed herein will be the first to measure in humans the relationships among (i) the liver's ability to burn fat and make glucose, two of its primary functions; (ii) the severity of nonalcoholic fatty liver disease; and (iii) the responses to bariatric surgery. These experiments will support deeper future mechanistic investigations of the metabolic mechanisms underlying nonalcoholic steatohepatitis (NASH) improvement with bariatric surgery. The premise of this study is that deranged hepatic mitochondrial metabolism is a key biomarker and mediator of the nonalcoholic fatty liver disease (NAFLD)/NASH continuum, and the central hypothesis the investigators will test is that preoperative hepatic fat oxidation and glucose production flux parameters differ between low versus high NAFLD activity score (NAS), and response of the liver to bariatric surgery can be predicted by preoperative fluxes.