Alcoholic Hepatitis: Molecular Mechanisms

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DESCRIPTION (provided by applicant): Alcohol accounts for nearly 100,000 deaths and public health costs are more than $116 billion per year. Neutrophilic steatohepatitis is one of the important pathologic findings in chronic alcoholics which represents a rate-limiting step in the progression to firbrosis/cirrhosis and clinical liver disease. Although significant advances have been made in our general understanding of the mechanisms of hepatic neutrophil infiltration over the last decade, the precise reason for neutrophil migration from hepatic vasculature to hepatocyte attachment and death are currently unknown. Clearly, understanding the mechanistic basis for hepatic neutrophil infiltration in chronic alcoholic patients is of high priority. In this project, our specific aims are three fold, and are based on the central hypothesis that osteopontin (OPN), a matricellular protein is induced in the rodent alcoholic hepatitis model and induction of OPN is the reason behind neurophil infiltration into hepatic parenchyma. It is further postulated that OPN-mediated hepatic neutrophil infiltration is preceded by neutrophil activation within the hepatic vasculature. Our experiments will focus on assessing OPN mRNA and protein expression in the in vivo alcoholic hepatitis Lieber DeCarli diet rodent model by in situ hybridization, RT-PCR, immunohistochemistry and Western blotting which is then correlated with hepatic neutrophil infiltration and liver injury. The in vivo rodent model of alcoholic hepatitis and in vitro studies will then investigate the role of OPN in neutrophil activation prior to neutrophil transmigration into liver by assessing L-selectin and Mac-1 (¿2integrin) integrin) by flow cytometry. Finally, the central role of OPN will be confirmed using OPN OPN-/- -/- mice and interventional experiments using neutralizing antibody against OPN in mice. The long-term goal of this project is to device appropriate therapies that will prevent neutrophilic steatohepatitis in chronic alcoholics by reducing neutrophil infiltration into liver.