Role of Hepatokines in Alcohol-associated Liver Disease - Abstract Alcohol-associated hepatitis (AH) is a severe and life-threatening form of alcohol-associated liver disease (ALD) with high short-term mortality. Hepatocytes are the primary alcohol metabolizing cells, and excess alcohol consumption has direct detrimental effect on hepatocytes. While it is evident that alcohol-induced metabolic perturbations in the hepatocytes contribute to inflammation and dysregulated immune response, the specific mechanisms by which hepatocytes alter the immune cell function in AH remains unclear. Recently, hepatokines, predominantly hepatocyte secreted proteins, have drawn significant attention due to their metabolic, and immunomodulatory effects on immune and non-immune cells. Hepatokines can regulate immune cell activation and function, inflammation, steatosis, and liver damage. However, the role of hepatokines in ALD/AH is unknown. Our preliminary data from hepatokine profiling using human and mice liver and serum with AH, showed elevated levels of hepatokine, Fibrinogen Like 1 (FGL1) which correlated with increased disease severity. Previous reports indicate a positive correlation of serum (and liver) FGL-1 levels with hepatic steatosis, and inflammation. Reportedly, FGL-1 interacts with its receptor LAG3 (co-inhibitory receptor on T cells) resulting in immune cell exhaustion, a feature classically associated with AH patients. Consistent with this, we found increase in LAG3 expression in human and mice liver with AH. Thus, we hypothesized that FGL1/LAG3 is involved in the pathogenesis of AH, altering immune cell function. FGL1 is known to be transcriptionally regulated by IL6/STAT3 signaling. Our novel data indicate that in primary mouse and human hepatocytes, alcohol-induces the phosphorylation of a key signaling kinase, Bruton’s tyrosine kinase (BTK), and using a BTK inhibitor, significantly reduced alcohol-induced pSTAT3, IL6, and FGL1. Thus, we provide the mechanism by which FGL1 is regulated by BTK in hepatocytes. In preclinical models of AH, we will use FGL1-/- mice to assess liver inflammation, damage, and immune cell function. Using hepatic-BTK deletion in mice, we will assess the role of hepatic-BTK in regulating FGL1, in vivo. Using FDA approved LAG3 inhibitor we will assess the immune cell function in AH. Lastly, using FGL1 neutralizing antibodies, we will assess therapeutic benefits in mice with AH. Results from this study will define the role of, FGL1 in regulating steatosis, inflammation, and immune cell function, in AH. These novel findings will highlight the therapeutic potential using FDA approved LAG3 inhibitor/FGL1 antibodies to restore immune cell function in AH.
