Single-Cell Characterization of Hepatic CD8+ T Cells in a Murine Model of Primary Biliary Cholangitis

Targeting pathogenic CD8+ tissue-resident T cells with chimeric antigen receptor therapy in murine autoimmune cholangitis

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.

[High expression of COX6B2 in gastric cancer is associated with poor long-term prognosis and promotes cell proliferation and cell cycle progression by inhibiting p53 signaling]

OBJECTIVE

To investigate the effect of COX6B2 expression in gastric cancer tissues on the patients' long-term prognosis and its underlying mechanism.

METHODS

Based on the public databases and the medical records of patients, we analyzed the expression level of COX6B2 in gastric cancer and adjacent tissues and its influence on long-term prognosis of the patients. Enrichment analysis were used to predict the possible role of COX6B2 in gastric cancer. The effects of lentivirusmediated COX6B2 knockdown on biological behaviors of gastric cancer cells were examined using CCK-8 assay, flow cytometry, and Western blotting.

RESULTS

TCGA database and the results of immunohistochemistry, Western blotting and realtime PCR all demonstrated a significantly higher expression of COX6B2 in gastric cancer tissues (P < 0.05). Kaplan-Meier plotter database and Kaplan-Meier curves showed that the patients with high COX6B2 expression had significantly shorter postoperative survival (P < 0.05). A high expression of COX6B2 in gastric cancer tissues was closely correlated with clinicopathologic stage, CEA and CA19-9 (P < 0.05). A high expression of COX6B2, CEA level≥5 μg/L and CA19-9 level≥37 kU/L were independent risk factors affecting postoperative 5-year survival rate of gastric cancer patients (P < 0.05), and COX6B2 expression level had a predictive value for long-term prognosis of the patients (P < 0.05). GO and KEGG enrichment analyses showed that COX6B2 was mainly involved in the regulation of cell cycle. In the in vitro cell experiment, COX6B2 overexpression significantly promoted gastric cancer cell proliferation, increased the percentage of G1/S phase cells and inhibited the cellular expressions of p53 and p21 (P < 0.05).

CONCLUSION

s COX6B2 is highly expressed in gastric cancer and is closely correlated with a poor long-term prognosis of the patients possibly by promoting gastric cancer cell proliferation and regulating cell cycle.

Regulatory T cells in inflamed liver are dysfunctional in murine primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic autoimmune disease characterized by immune-mediated destruction of intrahepatic small bile ducts. CD8 T cells play a critical role in biliary destruction. However, regulatory T cells (Tregs) have also been identified in the portal tracts of PBC patients. This study tested the hypothesis that hepatic Tregs in PBC were dysfunctional in suppressing immune responses in disease by using our human PBC-like autoimmune cholangitis (AIC) mouse model induced by 2-octynoic acid-conjugated ovalbumin (2-OA-OVA). Our results showed that female and male mice immunized with 2-OA-OVA developed AIC; however, female AIC mice had more severe liver inflammation and fibrosis than male AIC mice. Levels of functional effector CD8 T cells and their chemoattractants, CXCL9 and CXCL10, in the liver were markedly elevated in female AIC mice than in male AIC mice. These results reinforce that CD8 T cells are the primary effector cells in PBC. The number of hepatic Tregs in AIC mice was also higher than in saline-treated mice, but there was no difference between male and female AIC mice. The suppressive function of AIC Tregs was evident despite a discrepancy in the changes in their co-inhibitory receptors and inhibitory cytokines. However, the expansion of hepatic Tregs by low-dose IL-2 treatment did not reduce immune responses to AIC, which may be due to the dysfunction of Tregs in inhibiting T cells. In conclusion, the function of Tregs in the inflamed liver of PBC was insufficient, and low-dose IL-2 treatment could not restore their function to suppress pathological immune responses. Transferring normal Tregs or directly targeting effector CD8 T cells may be beneficial for treating PBC.

Animal models of primary biliary cholangitis: status and challenges

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune liver disease. The aetiology of PBC remains unclear, and its pathogenesis is complex. Animal models are essential to clarify the pathogenesis of PBC and explore the occurrence of early events.

MAIN BODY

Herein, we review recent research progress in PBC animal models, including genetically modified, chemically inducible, biologically inducible, and protein-immunised models. Although these animal models exhibit several immunological and pathological features of PBC, they all have limitations that constrain further research and weaken their connection with clinical practice.

CONCLUSION

The review will benefit efforts to understand and optimise animal models in order to further clarify PBC pathogenesis and molecular targets for therapeutic interventions.

Research progress on the application of single-cell sequencing in autoimmune diseases

Autoimmune diseases (AIDs) are caused by immune tolerance deficiency or abnormal immune regulation, leading to damage to host organs. The complicated pathogenesis and varied clinical symptoms of AIDs pose great challenges in diagnosing and monitoring this disease. Regrettably, the etiological factors and pathogenesis of AIDs are still not completely understood. It is noteworthy that the development of single-cell RNA sequencing (scRNA-seq) technology provides a new tool for analyzing the transcriptome of AIDs. In this essay, we have summarized the development of scRNA-seq technology, and made a relatively systematic review of the current research progress of scRNA-seq technology in the field of AIDs, providing a reference to preferably understand the pathogenesis, diagnosis, and treatment of AIDs.