Gamma-ketoaldehyde scavengers for alcoholic liver disease

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DESCRIPTION (provided by applicant): Chronic alcohol overconsumption is the third largest risk factor for disease burden worldwide and is a frequent comorbidity of liver disease and cancer. While abstinence is a cornerstone of treatment, there is considerable interest in identifying other therapeutic interventions for alcoholic liver disease (ALD). Such advances are complicated by an incomplete understanding of the relationship between alcohol-specific metabolic responses and liver pathophysiology. The induction of a pro-inflammatory state, hallmark of ALD, appears to depend upon the unfavorable interplay among reactive oxygen species (ROS), protein adduct formation, and both the innate and adaptive immune responses. In this SBIR Phase I project, we hypothesize that the formation of highly reactive compounds, termed γ-ketoaldehydes (γ-KA), formed primarily by non-enzymatic free radical catalyzed lipid peroxidation and secondarily by cyclooxygenases (COX) activity, is crucial for ethanol-induced liver injury. γ-KAs react very rapidly with protein lysyl residues to form stable lactam adducts which elicit specific immune reactions. The formation of these γ-KA-protein adducts lead to immunogenicity, inflammation and end-organ damage. Hence, the use of selective scavengers of γ-KAs should lead to interruption of the pathogenic inflammatory responses leading to improvements in ALD. It has become increasingly evident that the interplay among ROS, lipid peroxidation and immune responses is important in the pathogenesis of ALD. Our collaborator (LJ Roberts, MD) has identified Salicylamine as an agent that rapidly and preferentially reacts with γ-KAs to prevent their adduction to cellular proteins and other amines. The goal of this proposal is to test the hypothesis that hepatic γ-KA scavenging will reduce liver injury (ALT) and have differential effects on innate and adaptive immune responses in ALD. We will determine the effects of orally administered Salicylamine on reducing the severity of alcohol liver injury an on immune responses in acute (2 day) and chronic (25 day) ethanol-fed mouse models. In study 1, we will examine the dose-response effects of Salicylamine on liver function (ALT, AST, triglyceride), as well as hepatic and circulating γ-KAs, anti-γ-KA antibody titers as well as livr monocyte infiltration when Salicylamine is administered concurrent with ethanol. We anticipate Salicylamine will significantly reduce protein adduction formation and improve liver function in a manner that is concordant with diminished adaptive immune responses including T and B cell proliferation, NFκB activation and TLR4 signaling. In study 2 we will employ the same 2 day and 25 day ethanol-fed mouse models to induce liver injury, but will administer Salicylamine (in a dose-dependent manner) after the primary ethanol administration then monitor the same endpoints as in study 1. If these studies demonstrate that Salicylamine reduces alcohol liver injury and/or have a differential effect on immune responses, Phase II studies will be proposed to further refine the mechanisms of action of Salicylamine desired for product development and regulatory approvals in a subsequent SBIR grant.