Zhi-Bin Zhao

Inositol-requiring enzyme 1α (IRE1α) and the downstream spliced form of X-Box Binding Protein 1 (XBP1s) have been identified as tumor promotors. However, how IRE1α–XBP1s signaling affects tumor progression in a non-cell autonomous manner remains unclear. Here we show that the hepatocyte IRE1α–XBP1s axis unexpectedly inhibits liver metastasis by confining local metainflammation. Genetic ablation of IRE1α or XBP1 in mouse hepatocytes exacerbates liver metastasis due to the accumulation of inflammatory monocytes (IMs). Mechanistically, a non-canonical Forkhead box O1 (FoxO1)-glutamine synthetase (GS) pathway endows the IRE1α- or XBP1-null hepatocytes with the metabolic activity to secrete glutamine, which is necessary and sufficient for IM fitness. Reintroduction of hepatocyte XBP1s or blockade of glutamine metabolism effectively reduces IMs and mitigates disease progression. Importantly, clinical patient survival with liver metastases positively correlates with hepatocyte XBP1s expression. Our study defines a paradigm of hepatocyte–IM interaction that can be leveraged to treat liver metastasis.

Background: Kupffer cells and monocyte-derived macrophages (MoMs) are difficult to study in human primary biliary cholangitis (PBC) even though they reflect a dynamic hepatic immune population. Objective: We aim to investigate the role of hepatic macrophage and its therapeutic potential in human PBC and murine autoimmune cholangitis. Design: Phenotypic analysis of hepatic macrophages in patients with PBC and dnTGFβRII mice model was performed by single-cell RNA sequencing, flow cytometry and immunohistochemistry. Depletion of hepatic macrophages and inhibition of MoMs were performed in murine autoimmune cholangitis. Lyz2-Cre -mediated Atg5 knockout mice and co-culture experiments were applied to explore the role and mechanism of macrophage autophagy in autoimmune cholangitis. Therapeutic intervention was performed using nanoparticle-capsuled small interfering RNA against Atg5 . Results: Kupffer cells from patients with PBC and dnTGFβRII mice upregulate genes associated with inflammatory responses and exhibit increased autophagy. Further, macrophage-specific knockout of Atg5 leads to reduction of inflammation and bile duct damage. We propose that the mechanism of this modulation is secondary to decreased activation of pathogenic CD8 ⁺ T cells. Indeed, Kupffer cells maintain CD8 ⁺ T cell tolerance through expression of inducible nitric oxide synthase (iNOS) and generation of NO. Increased autophagy resulted in degradation of iNOS in Kupffer cells and abrogated their suppressive activity against CD8 ⁺ T cells. Finally, we report that targeted downregulation of Kupffer cell autophagy in vivo using cationic lipid-assisted nanoparticles encapsulating siRNA against Atg5 leads to reduction of liver inflammation and bile duct damage. Conclusion: Macrophage autophagy promotes autoimmune cholangitis and strongly supports this pathway as a potential therapeutic target.

The specific mechanisms underlying effector pathways in autoimmune liver disease remain enigmatic and therefore constructing appropriate murine models to investigate disease pathogenesis becomes critical. A spontaneous severe murine model of autoimmune liver disease has been previously established in dnTGFβRII Aire ^−/− mice, exhibiting disease phenotypes that resemble both human primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH). The data suggests that auto‐reactive liver‐specific CD8 ⁺ T cells are the primary pathogenic cells in liver injury. In this study, these data are advanced through the use of both single‐cell sequencing and extensive in vitro analysis. The results identify a specific expanded pathogenic subset of PD‐1 ⁺ CD8 ⁺ T cells in the liver, exhibiting strong functional activity and cytotoxicity against target cells. Depletion of PD‐1 ⁺ CD8 ⁺ T cells using CAR‐T cells effectively alleviates the disease. GSDMD‐mediated pyroptosis is found to be aberrantly activated in the livers of model mice, and treatment with a GSDMD‐specific inhibitor significantly inhibits disease progression. In vitro experiments reveal that PD‐1 ⁺ CD8 ⁺ T cells can induce the pyroptosis of hepatocytes through elevated production of granzyme B and perforin‐1. These results provide a novel explanation for the cytotoxic activity of pathogenic liver PD‐1 ⁺ CD8 ⁺ T cells in autoimmune liver diseases and offer potential therapeutic targets.

Extrahepatic cholangiocarcinoma (ECC), a highly malignant type of cancer with increasing incidence, has a poor prognosis due to limited treatment options. Based on genomic analysis of ECC patient samples, here we report that aldo-keto reductase family 1 member C1 (AKR1C1) is highly expressed in human ECC tissues and closely associated with ECC progression and poor prognosis. Intriguingly, we show that inducible AKR1C1 knockdown triggers ECC cells to undergo ferroptosis. Mechanistically, AKR1C1 degrades the protein stability of the cytochrome P450 family member CYP1B1, a newly discovered mediator of ferroptosis, via ubiquitin-proteasomal degradation. Additionally, AKR1C1 decreases CYP1B1 mRNA level through the transcriptional factor aryl-hydrocarbon receptor (AHR). Furthermore, the AKR1C1–CYP1B1 axis modulates ferroptosis in ECC cells via the cAMP–PKA signaling pathway. Finally, in a xenograft mouse model of ECC, AKR1C1 depletion sensitizes cancer cells to ferroptosis and synergizes with ferroptosis inducers to suppress tumor growth. Therefore, the AKR1C1–CYP1B1–cAMP signaling axis is a promising therapeutic target for ECC treatment, especially in combination with ferroptosis inducers.

Primary biliary cholangitis (PBC) is a cholestatic autoimmune liver disease characterized by autoreactive T cell response against intrahepatic small bile ducts. Here, we use Il12b^-/-Il2ra^-/- mice (DKO mice) as a model of autoimmune cholangitis and demonstrate that Cd8a knockout or treatment with an anti-CD8α antibody prevents/reduces biliary immunopathology. Using single-cell RNA sequencing analysis, we identified CD8⁺ tissue-resident memory T (Trm) cells in the livers of DKO mice, which highly express activation- and cytotoxicity-associated markers and induce apoptosis of bile duct epithelial cells. Liver CD8⁺ Trm cells also upregulate the expression of several immune checkpoint molecules, including PD-1. We describe the development of a chimeric antigen receptor to target PD-1-expressing CD8⁺ Trm cells. Treatment of DKO mice with PD-1-targeting CAR-T cells selectively depleted liver CD8⁺ Trm cells and alleviated autoimmune cholangitis. Our work highlights the pathogenic role of CD8⁺ Trm cells and the potential therapeutic usage of PD-1-targeting CAR-T cells.

In this study, we comprehensively charted the cellular landscape of colorectal cancer (CRC) and well-matched liver metastatic CRC using single-cell and spatial transcriptome RNA sequencing. We generated 41,892 CD45 ⁻ nonimmune cells and 196,473 CD45 ⁺ immune cells from 27 samples of six CRC patients, and found that CD8_CXCL13 and CD4_CXCL13 subsets increased significantly in liver metastatic samples that exhibited high proliferation ability and tumor-activating characterization, contributing to better prognosis of patients. Distinct fibroblast profiles were observed in primary and liver metastatic tumors. F3 ⁺ fibroblasts enriched in primary tumors contributed to worse overall survival by expressing protumor factors. However, MCAM ⁺ fibroblasts enriched in liver metastatic tumors might promote generation of CD8_CXCL13 cells through Notch signaling. In summary, we extensively analyzed the transcriptional differences of cell atlas between primary and liver metastatic tumors of CRC by single-cell and spatial transcriptome RNA sequencing, providing different dimensions of the development of liver metastasis in CRC.