EphB2 deficiency in hepatic stellate cells mitigates fibrogenesis in metabolic dysfunction-associated steatohepatitis by attenuating the TGFβ/SMAD signaling
Authors: Kamdem Severin Donald , Pellizzari Sarah , Yoshigi Masaaki , Kameni Ernest , Pham Tuan , Evason Kimberley , Boudina Sihem 
Published: May 2024

Background & Aims: The receptor tyrosine kinase EphB2 is now emerging as a critical regulator of inflammation and fibrogenesis in metabolic dysfunction-associated steatohepatitis (MASH) though the underlying mechanism remain unclear. We aimed to investigate the role or mechanism by which EphB2 contributes in the progression of MASH fibrogenesis. Hypothesis: We hypothesized that EphB2 in hepatic stellate cells (HSCs) promotes MASH-liver fibrosis Methods: Single nuclear RNA-sequencing of liver from human and mouse MASH were analyzed for EphB2 expression. Human liver biopsies obtained from patients with MASH were used to assess EphB2 expression by immunohistochemistry. Primary human HSCs were stimulated with TGFβ with or without TGFβR/SMAD inhibitors (SB525334, CS208, and SIS3 at 1μM) and EphB2 expression assessed by qPCR, western blot and immunofluorescence staining. EphB2 was silenced in primary human HSCs using siRNA and the resulting HSCs assess for TGBβ-induced HSC-myofibroblasts transition. MASH models were developed in hepatocyte-specific EphB2 knockout and HSCs EphB2 knockout and wild-type mice fed a high fat diet for 26 weeks or a choline-deficient amino-acid defined (CDAA) high fat diet for 10 weeks. Statistical analysis was performed using GraphPad Prism and a p-value < 0.05 was considered significant. Results: The expression of EphB2 was 3-fold significantly upregulated in liver specimens from patients with advanced MASH and correlated with disease severity. EphB2 was modestly expressed in hepatocyte, but strongly induced in HSCs in human and mouse MASH. Hepatocyte-specific EphB2 deficiency does not inhibit the development of steatohepatitis and fibrosis in mice fed the CDAA-diet. TGFβ/SMAD signaling promotes an 8-fold increase of EphB2 expression in human HSCs while siRNA silencing of EphB2 in human HSCs was suffcient to abolished TGFβ-mediated HSCs activation. Interestingly, HSCs-specific EphB2 knockout mice developed 2.5 to 6-fold less fibrosis than wild-type controls in response to high fat diets feeding suggesting that EphB2 expression on HSCs is required for the development of fibrogenesis in MASH. Deletion of EphB2 in activated HSCs after fibrosis was established in mice was suffcient to mitigate MASH fibrosis. Conclusions: EphB2 is upregulated in human and mouse MASH. Upregulation of EphB2 in human HSCs is mediated via the TGFβ/SMAD signaling. HSCs expressing EphB2 regulate the development of MASH-fibrosis. Specific EphB2 inhibitors could potentially mitigates fibrogenesis in MASH, opening up an avenue for the treatment of MASH.

Funding sources: NIDDK, NIAMS, APS postdoctoral fellowship.

This is the full abstract presented at the American Physiology Summit 2024 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.