Characterization of acetaldehyde-protein adducts in alcohol-associated liver disease - Project Summary/Abstract Ethanol consumption has been on the rise throughout the COVID-19 pandemic and one of the major consequences has been a surge in alcohol-associated liver disease (ALD), especially severe alcoholic hepatitis (sAH). sAH is a life-threatening condition with 30-day patient mortality greater than 30%, limited treatment options, and often requires a liver transplant. There is an urgent need to identify novel mechanisms of ALD progression that are potential targets for treatment. The ethanol metabolite acetaldehyde (AcH) is known to form adducts on lysine residues within proteins, which affect protein function. Many proteins are known to bind to AcH, but no one has characterized the overall composition or downstream effects of these protein modifications on the pathogenesis of ALD. Albumin is one of the major proteins known to bind to AcH, and these AcH adducts mostly occur on the many exposed lysine residues throughout the albumin molecule. The fact that a single albumin can bind many AcH molecules combined with albumin being the most abundant protein in the liver and circulation means that albumin may act as a “sponge” for excess AcH. Therefore, any decrease in albumin levels may lead to increased modification of other proteins, having deleterious effects on ethanol-induced organ injury. My preliminary data shows that plasma albumin levels are decreased in heavy drinkers compared to control subjects in the absence of liver dysfunction. In albumin-deficient mice, ethanol feeding leads to decreased lymphocyte accumulation in the liver, but the mechanism is unknown. This project is designed to test the overarching hypothesis that albumin alters the distribution of AcH-protein adducts after ethanol consumption, modulating lymphocyte function in ALD. In Aim 1 (K99 phase) I will receive training from my mentor, Dr. Bin Gao, to determine how AcH and albumin regulate lymphocyte function. In Aim 2 (K99 phase), I will receive training in proteomic methods and analysis from my committee member Dr. Fritz to characterize the AcH-protein adductome in immune cells and albumin-deficient mice. In Aim 3 (R00 phase), I will use the training from the K99 phase to analyze public proteomic datasets and identify specific AcH-protein adducts that are present in patients with ALD. I will utilize cellular models to determine how these modifications impact immune cell and hepatocyte functions in the context of ALD. This project will provide a framework for how AcH-protein adducts modulate ALD using albumin as a model protein. The training provided by this grant will provide the PI with a strong foundation to achieve his long-term goal of identifying systemic mediators of ethanol-induced liver injury to develop therapeutics that protect against alcohol-induced injury in multiple ways. The NIAAA will provide an ideal environment for cross-disciplinary training and the necessary resources to transition to independence.
