LAUSR

Background & Aims: Emerging evidence suggests that the receptor tyrosine kinase EphB2 regulates tissue inflammation and fibrosis. However, its contribution to non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD or NASH) remains largely unknown; thus, we aimed to determine its role. Methods: In NAFLD/NASH patients, hepatic EphB2 and serum EphrinB2 ligands were evaluated. Disease phenotyping was performed in male and female wild type (WT), EphB2-/-, EphB2-kinase-dead (EphB2K661R), EphB2-kinase-overactive (EphB2F620D) mice, and in macrophage-specific EphB2-/- mice fed the obesogenic Gubra-Amylin NASH diet for 22-28 weeks and the Choline Deficient Amino-acid improved high-fat diets for 10-12 weeks. The role of EphB2 in inflammation was investigated in bone marrow-derived macrophages. Pharmacological inhibition of EphB2 for the treatment of NASH was also evaluated in vivo. Histology, hydroxyproline assay, flow cytometry, gene expression, biochemical assays, and RNA sequencing were used to dissect the molecular mechanism underlying macrophages’ EphB2 function in NASH. Results: Hepatic EphB2 was strongly upregulated in NASH patients and correlated with NASH fibrosis score. Serum EphrinB2 was also elevated in NASH patients. In mouse models of NASH, EphB2-/- mice showed a significant reduction in liver steatosis, inflammation, and fibrosis compared to WT mice. This is supported by a significant reduction of liver fat content, pro-inflammatory and fibrotic genes in EphB2-/- compared to WT mice. EphB2 forward signaling is likely the main driver of NASH progression as depicted by the significant increase in steatosis, inflammation, and fibrosis observed in EphB2F620D compared to WT and EphB2K661R mice. Flow cytometry revealed a reduced macrophage population in EphB2-/- mice compared to WT mice.In addition, bone marrow-derived macrophages from EphB2-/- mice showed reduced inflammation when stimulated with LPS in vitro. Interestingly, macrophage-specific EphB2-/- showed a reduction of NASH fibrosis and associated metabolic syndrome. Conclusions: We have identified EphB2 as a key player in the pathogenesis of fatty liver disease in humans and mice and its therapeutic targeting could potentially mitigate NASH fibrosis and associated metabolic syndrome National Institutes of Health (NIH) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.