Kinetics of Metabolic Cofactors in NAFLD

Overview

There is a strong correlation between major adverse health consequences of obesity and development of non-alcoholic fatty liver disease (NAFLD). NAFLD is characterized by abnormal hepatic accumulation of triglycerides and other lipids. It has become a worldwide health problem that accelerates cirrhosis, type 2 diabetes mellitus (T2DM), and especially premature cardiovascular morbidity and mortality. The plasma level of glutathione (GSH) is typically depleted in individuals with metabolism related disorders. However, cellular GSH levels cannot be increased by supplementing GSH and it must be synthesized within the liver either de novo or by salvation pathway. The level of GSH is not enough to maintain and regulate the thiol redox status of the liver in subjects with high hepatic steatosis at fasting stage due to the depletion of glycine. Glycine can be synthesized via the interconversion of serine. It has been shown that the serine synthesis is downregulated in patients with NAFLD and supplementation of serine has attenuated alcoholic fatty liver by enhancing homocysteine metabolism in mice and rats. Depleted liver glutathione is also restored by the administration of N-acetylcystein as in acetaminophen poising. L-carnitine and nicotinamide that both stimulate the transfer of fatty acids from cytosol to mitochondria have been identified as two additional cofactors that are depleted in patients with NAFLD. In this study, the kinetics in blood of pivotal metabolic cofactors, serine, L-carnitine, N-acetylcystein and nicotinamide after single and simultaneous dietary supplementation, are measured.

In 10 healthy subjects with BMI \<30 kg/m2 the plasma concentrations of 4 natural compounds (nicotinamide riboside, L-carnitine, L-serine and N-acetylcystein) are measured by ultra-performance liquid chromatography-tandem mass spectrometry (UPLCMSMS) after individual and combined administration, on five consecutive days and at every hour during 9 hours after administration. The study will start at 8:00 every morning and at each time point, blood samples will be collected. The taste and any potential sensing of the co-factors such as vertigo, nausea, bowel movement will be recorded. Each participant will receive one oral dose of Day 1: 1 g nicotinamide riboside; Day 2: 3 g L-carnitine; Day 3: 5 g N-acetylcystein; Day 4: 20 g L-serine; Day 5: combined 1 g nicotinamide riboside, 3 g L-carnitine, 5 g N-acetylcystein, and 20 g L-serine In addition, untargeted metabolomics analysis as well as O-link proteomics analysis we be performed to study effect of the administered cofactors.