Mechanism of neutrophilic NCF1 in alcohol-associated liver disease pathogenesis

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Project Summary Alcohol-associated liver disease (ALD) is a complex disease and represents a spectrum of histopathological changes in the liver. Accumulating evidence suggests that multiple types of immune cells are involved in the pathogenesis of alcohol-associated hepatitis (AH), particularly neutrophils. However, the mechanisms underlying neutrophils in mediating AH pathogenesis are not well understood. Our exploratory experiments had led to an important and clinical observation on the inter-patient variability and two distinct patterns of hepatic neutrophil infiltration. Our data also indicated that higher level of hepatic parenchymal neutrophils was associated with AH disease severity. The key question we would like to address in this application is how neutrophils drives disease severity and mediates liver injury in ALD. Mechanistically, neutrophils, as an innate inflammatory response, mediates tissue injury by producing inflammatory mediators and reactive oxygen species (ROS). ROS production in neutrophils is regulated by the multi-meric transmembrane enzyme complex, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). Among them, the NCF1 gene, which encodes the phagocytic oxidase (phox) unit p47phox, is predominantly expressed in neutrophils and plays an important role in controlling ROS production in neutrophils. Our data suggested that miR-223, the most abundant neutrophilic miRNA, may be a downstream target of NCF1 and its induction ameliorates alcohol-induced liver injury. In specific aim#1, we will determine the molecular mechanism on the inhibition of neutrophilic miR-223 by NCF1. Our data and planned experiments in specific aim#1 will expand our current knowledge on the signaling pathway in the neutrophils, neutrophilic Ncf1-induced oxidative stress, and miR- 223 expression. The next important question to address is how the inhibition of miR-223 by NCF1-induced oxidative stress leads to hepatocyte injury. In specific aim #2, we will determine the downstream crosstalk between neutrophil-induced ROS generation and hepatocytes via extracellular vesicles (EVs) leading to alcohol-induced liver injury. Taken together, we have developed animal and cellular models to mechanistically examine the roles of neutrophils in ALD pathogenesis. Understanding the mechanism linking neutrophils to ALD pathogenesis is of importance; this will pave a way for the discovery of potential targeted therapy for patients with ALD.