Since 1997, Professor Jian Wu’s research group at Fudan University Shanghai Medical College has been actively participating in the annual meeting of the American Association for the Study of Liver Diseases (AASLD 2023). This year, the research group has had four abstracts selected for poster presentations and one abstract chosen for an oral presentation in a thematic session. The selected abstracts primarily focus on three main topics: the molecular basis of the Hedgehog signaling pathway in hepatocellular carcinoma; the molecular mechanisms of the JCAD protein in liver fibrosis and regeneration; and the mechanisms by which gut microbiota-derived metabolites promote the progression of chronic liver disease. “Hepatology Digest” had the privilege of inviting Dr. Jian Wu to the conference to discuss the research findings and their significance, share insights and advice on scientific research, and talk about the topics and experiences that caught his interest during the conference. The interview video and summaries of the five research presentations are provided below.

Hepatology Digest ▲ Dr. Jian Wu Interviewed Live at AASLD 2023

Research One

Oral #43552 | Gut Microbe-produced Imidazole Propionate Aggravated Hepatic Fibrosis by Boosting Hepatocellular Death and M1 Macrophage Polarization.

First Author: Qin Zhu, PhD candidate, Department of Gastroenterology, Zhongshan Hospital, Fudan University.

This study proposes that imidazole propionate (ImP), a tryptophan-derived metabolite from the gut, promotes hepatocellular death and exacerbates liver fibrosis through the “gut-liver axis.” The research reveals that the levels of ImP in the blood of patients with chronic hepatitis B/cirrhosis are significantly higher compared to the healthy control group. In mouse models of fibrosis induced by carbon tetrachloride toxicity and HBV infection, intraperitoneal injection of ImP further worsens liver damage and fibrosis. ImP promotes the expression of DNA damage marker phosphorylated H2AX and oxidative stress, leading to the infiltration of liver macrophages. Isolated bone marrow-derived macrophages (BMDM) from mice, when induced with lipopolysaccharide (LPS) to M1 polarization, showed significantly upregulated gene expression associated with M1 macrophage polarization in the presence of ImP. Treatment of primary mouse liver cells with LPS combined with ImP significantly increased liver damage compared to LPS alone, and the supernatant further enhanced the pro-inflammatory polarization of BMDM. BMDMs treated with LPS combined with ImP promoted the activation of hepatic stellate cells. Therefore, gut microbiota-derived metabolite imidazole propionate may exacerbate liver fibrosis by promoting hepatocellular death and M1 macrophage polarization. The study suggests that gut microbiota-derived metabolites could potentially serve as targets for the treatment of chronic liver diseases.

Poster #3427-A | Secretome of Senescent Hepatic Stellate Cells Favors Malignant Transformation from Nonalcoholic Steatohepatitis-Fibrotic Progression to Hepatocellular Carcinoma. First Author: Yuan Zhou, Outstanding Master’s Graduate from the School of Basic Medical Sciences, Fudan University, 2023.

This study proposes a new hypothesis that senescent hepatic stellate cells promote malignant transformation of liver cells from nonalcoholic steatohepatitis (NASH)-fibrotic progression to hepatocellular carcinoma (HCC) through the secretion of protein components that favor inflammatory lipid transformation. Activated hepatic stellate cells can undergo apoptosis or senescence. Using a high-fat, high-sugar diet-fed mouse model, the study observed a dynamic change in the gradual increase and subsequent decrease of senescent hepatic stellate cells during the progression from simple fatty liver to NASH-fibrosis-HCC. Using unlabeled quantitative mass spectrometry-based proteomics, the complete secretome expression profile of senescent hepatic stellate cells was analyzed. The results revealed that the secretome of senescent hepatic stellate cells, after activation and senescence, contains key cytokine components that influence proliferation, epithelial-mesenchymal transition, or migration. The secreted proteins from senescent hepatic stellate cells can activate the β-catenin/Wnt and Hedgehog signaling pathways within liver cells, thereby accelerating the malignant transformation of lipid-transformed liver cells. The study suggests that the increased specific secretome components of senescent hepatic stellate cells are important factors driving malignant transformation of liver cells in the context of chronic inflammatory fibrosis. This novel concept contributes to the development of more rational strategies for intervening in the progression of NASH fibrosis.

Poster #4222-A | The Presence of TGF-β1/SMAD3-enhanced Gli2 Isoforms Contributes to Malignant Behaviors of Hepatocellular Carcinoma.

First Author: Dr. Jia Ding, Associate Chief Physician, Jing’an District Central Hospital, Shanghai.

This study introduces the activation of a non-classical Hedgehog signaling pathway mediated by TGF-β1/SMAD3, promoting the progression and metastasis of hepatocellular carcinoma (HCC). The Hedgehog signaling pathway consists of secreted ligands, transmembrane protein receptors, and the transcription factor GLI, with around 50-60% of HCC tissues expressing high levels of key molecules in this pathway. However, the study found that approximately 50% of GLI2 in liver cancer tissue does not depend on ligands but is activated by TGF-β1/SMAD3, identifying two new GLI2 isoforms. SMAD3 binds to GLI2, collectively initiating downstream gene transcription regulating stemness, epithelial-mesenchymal transition, drug resistance, and migration. Inhibiting TGF-β/SMAD3 signaling reduces lung metastasis in a mouse orthotopic liver transplantation tumor model. The non-classical Hedgehog signaling pathway is validated not only in a transgenic HBV-related HCC mouse model but also in clinical data showing that HCC patients with high GLI2 expression have significantly shorter disease-free survival than those with low expression. The study suggests that intervening in the non-classical Hedgehog signaling pathway could be a potential strategy for HCC treatment.

Poster #4575-C | Suppressing Cholestatic Fibrotic Progression by Targeting JCAD in Hepatic Stellate Cells.

First Author: Li Xie, PhD candidate, School of Basic Medical Sciences, Fudan University.

This study discovers that in cholestatic liver disease models, JCAD is a positive regulator in the process of liver fibrosis. JCAD promotes the transcription of fibrosis-promoting genes, including connective tissue growth factor, through the Hippo signaling pathway, actively participating in the activation and proliferation of hepatic stellate cells (HSC), leading to fibrosis. Primary biliary cholangitis (PBC), a representative of chronic cholestatic bile duct cell injury, is an autoimmune disease that often results in liver fibrosis progressing to cirrhosis, indicating end-stage liver disease. HSC activation is a major cause of liver fibrosis in PBC. The study finds that JCAD is strongly positive in liver biopsy sections of PBC patients and colocalizes with YAP, suggesting JCAD may be involved in the progression of PBC. Further investigation in bile duct-ligated mice reveals that JCAD is highly expressed simultaneously with smooth muscle α-actin when HSC is activated. Knocking out JCAD systemically or specifically in HSC reduces HSC activation and extracellular matrix synthesis, improving liver fibrosis. This effect is similar to the application of the YAP inhibitor verteporfin or YAP knockdown. The study elucidates the crucial role of JCAD in the activation of hepatic stellate cells, providing a potential molecular target to slow down the progression of cholestatic fibrosis.

Poster #4409-A | JCAD Deficiency Accelerates NASH-HCC Development through Leakage of Bile Acids due to Impaired Intrahepatic Biliary Duct Integrity.

First Author: Li Zhang, PhD candidate, School of Basic Medical Sciences, Fudan University.

This study reveals that JCAD deficiency promotes the progression of diet-induced nonalcoholic steatohepatitis-hepatocellular carcinoma (NASH-HCC) in mice. The incidence of nonalcoholic fatty liver disease-related hepatocellular carcinoma (NASH-HCC) is increasing year by year. JCAD, as a tight junction protein between liver cells, its deficiency results in impaired intrahepatic biliary duct integrity, leading to bile acid leakage. The toxicity of bile acids further promotes the progression of NASH-HCC. Two NASH-HCC models were employed in the study: a high-fat, high-energy diet with high-fructose and glucose water (HFCD-HF/G) model and a choline-deficient high-fat diet (CD-HFD) model, inducing primary NASH-HCC in JCAD knockout and wild-type mice, respectively, to simulate the natural progression of NASH-HCC. The study found that JCAD deficiency in both NASH-HCC models led to malignant progression, manifested by an increase in the number and heterogeneity of liver tumors. Characterization of tight junction proteins and intrahepatic biliary ducts through transmission electron microscopy indicated bile duct injury, compromised tight junction protein barrier, and bile stasis in JCAD knockout mice. At the genetic level, there was dysregulation in the expression of genes related to bile acid synthesis, metabolism, and transport. Further confirmation through fluorescence isothiocyanate (FITC)-dextran liver cell interstitial leakage and cell connection integrity testing confirmed the barrier function disruption of biliary epithelial cells caused by JCAD deficiency. This study suggests the promoting role of bile acids in the progression of NASH-HCC, providing potential therapeutic approaches for NASH-HCC.

Expert Introduction

Currently a distinguished professor at Fudan University School of Basic Medical Sciences, a dual-appointed professor in the Department of Gastroenterology at Zhongshan Hospital, Fudan University, and a doctoral supervisor.