Liver-specific glucocorticoid action in alcoholic liver disease.

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Project Summary Alcoholic hepatitis (AH) is a syndrome of inflammation, cholestasis, and liver failure with worsening profile in the US. The only available drug therapy for AH that moderately improve survival is glucocorticoids (GCs), with no new drugs successfully developed for decades. The rationale of GCs is to activate the glucocorticoid receptor (GR) to block cytotoxic and inflammatory pathways in AH patients. However, GC treatment of AH causes serious side effects, largely due to GCs’ adverse effects on extrahepatic tissues. Thus, liver-specific activation of GR may markedly improve AH therapy by minimizing GC’s extrahepatic adverse effects. A prerequisite for liver-specific GR targeting for alcoholic liver disease (ALD) is to fully understand the roles of liver-specific deficiency and activation of GR in ALD pathogenesis. Our long-term goal is to develop novel therapies for ALD. Bile acid (BA)-drug conjugates have been successfully developed for liver-specific drug targeting via the liver-specific BA transporter Na+-taurocholate cotransporting polypeptide (NTCP). We have successfully synthesized two first-in-class cholic acid (CA) conjugates of dexamethasone (DEX-CA) and verified their NTCP-dependent cellular uptake and activity. The objective of this R21 proposal is to develop these novel DEX-CAs as new drug candidates for ALD, and uncover how liver-specific deficiency and activation of GR regulate hepatic gene expression, metabolic homeostasis, and ALD pathogenesis. Our data mining found that AH human livers and livers from adult mice with hepatocyte-specific knockout of GR had highly similar down-regulation of certain key GR-target cytoprotective and anti-inflammatory genes, and impaired hepatic GR signaling was associated with cholestatic liver injury in our mouse studies. The central hypothesis is that GR in hepatocytes plays a key role in protecting against AH and alcoholic cirrhosis. By decreasing the adverse effects of GCs in extrahepatic tissues and exerting cytoprotective and anti- inflammatory effects on the liver, NTCP-mediated liver-specific GR activators will be a much-improved therapy for AH and a novel therapy for alcoholic cirrhosis. Aim 1 will characterize and optimize the pharmacokinetics and pharmacodynamics of the two classes of DEX-CAs in vitro and in vivo for maximum liver-specific GR activation. Aim 2 will delineate how liver-specific gene-dosage-dependent GR deficiency and activation of GR by DEX-CA affects ALD in mouse models of AH and alcoholic cirrhosis. This proposal is highly innovative because of its conceptual advances and up-to-date approaches. This study will develop highly innovative DEX-CA conjugates as new drug candidates and the first pharmacological tool for liver- specific activation of GR. It will uncover novel roles of gene-dosage-dependent GR deficiency and liver- specific activation of GR in regulating hepatic transcriptome, metabolic homeostasis and ALD pathogenesis, and whether the DEX-CA conjugate's actions are dependent on GR in hepatocytes. This will help develop novel improved therapy for AH and alcoholic cirrhosis via liver-specific activation of GR by DEX-CAs.