Acute alcoholic hepatitis (AH) is a severe inflammatory liver disease triggered by binge drinking. It has high mortality and treatment options are only poorly effective. AH only occurs in a small minority of heavy drinkers and most individuals appear to be protected from this form of liver injury. Previous work from our lab has identified the transcription factor FOXO3 as a possible protection factor and more recently we have determined that circulating monocytes from patients with AH have lost the ability to phosphorylate FOXO3 at S574 thus failing to generate a form of the protein (pFOXO3) that is normally induced by alcohol and appears to have protective, anti-inflammatory effects. This defect appears to result from abnormally high expression of the deacetylase SIRT7. It has long been known that macrophages and monocytes play an important role in the pathogenesis of AH. Blood monocyte counts are elevated in AH and both monocytes and macrophages have elevated inflammatory cytokine production in response to stimuli. This application will specifically examine blood monocytes and liver sections from patients with AH and heavy alcohol-consuming individuals who have never developed liver disease to determine the mechanisms that lead to abnormal FOXO3 phosphorylation in monocytes, the consequences of phosphorylation defects to abnormal monocyte function in AH, and whether or not abnormalities in the FOXO3 pathway serve as a susceptibility factor for the development of AH. We seek to test the hypothesis that alcohol consumption induces the formation of pFOXO3 in both monocytes and macrophages and pFOXO3 subsequently induces apoptosis and suppresses inflammatory cytokine production thus limiting alcohol-induced inflammation. We further hypothesize that high monocyte expression of SIRT7 prevents pFOXO3 formation and could serve as a potential therapeutic target. Finally, we propose to test whether variable ability to form pFOXO3 as a result of variations of SIRT7 expression plays a role in determining the intrinsic susceptibility of different individuals to alcoholic liver disease. We will test these hypotheses with two specific aims.
Aim 1 will determine the relationship between pFOXO3, SIRT7 and inflammatory responses in circulating monocytes from patients with acute alcoholic hepatitis. These experiments will involve obtaining blood monocytes from patients with alcoholic hepatitis and appropriate controls, and examining the relationship between FOXO3 phosphorylation and in vitro apoptosis and cytokine responses.
Aim 2 will examine the role of pFOXO3 in susceptibility to AH. These will examine blood monocytes from alcohol-consuming non-acutely ill patients with varying risk of development of AH, and liver sections from autopsy specimens from patients who died from alcohol-related MVAs. Overall, this proposal will use human disease specimens to rigorously test a novel mechanistic hypothesis of the pathogenesis of alcoholic hepatitis. and will extend the work from cell culture to mouse models to human patients with the ultimate goal of developing novel therapeutic approaches for this disease.
Alcoholic hepatitis is a severe acute liver disease that has high mortality and limited treatment options. This project will examine blood monocytes from patients with alcoholic hepatitis to determine whether abnormalities of the transcription factor FOXO3 lead to enhanced inflammatory responses. We will also determine if variations in the FOXO3 pathway contribute to risk of developing alcoholic hepatitis in sensitive individuals.
