Impaired antibacterial response of liver sinusoidal Vγ9+Vδ2+ T cells in patients with chronic liver disease

Investigating Human Liver Tissue-Resident Memory T Cells from the Perspectives of Gastroenterologists and Hepatologists

Liver tissue-resident memory T (TRM) cells play a pivotal role in hepatic immune responses. Their unique residence within liver sinusoids allow continuous antigen surveillance. In this review, we highlight the role of liver TRM cells in protective immunity and disease pathology. Comparisons between human and murine liver TRM cells reveal species-specific characteristics, suggesting the need for human-focused studies. One key finding is the involvement of liver TRM cells in viral hepatitis, where they can both control infection and contribute to liver damage. Liver TRM cells also exhibit dual roles in metabolic-associated steatotic liver disease, promoting inflammation and fibrosis while also contributing to fibrosis resolution. In autoimmune liver diseases, such as autoimmune hepatitis and primary sclerosing cholangitis, the presence of liver TRM cells correlates with disease severity. In this review, we underscore the importance of liver TRM cells in vaccine development, particularly vaccines against malaria. Future research should focus on the mechanisms governing TRM-cell formation, maintenance, and function, with the aim of supporting their protective roles while mitigating detrimental effects. Advancing our understanding of liver TRM cells will enhance our knowledge of liver immunology and inform novel therapeutic strategies for liver disease management.

Tissue-resident and innate-like T cells in patients with advanced chronic liver disease

Chronic liver disease results from the orchestrated interplay of components of innate and adaptive immunity in response to liver tissue damage. Recruitment, positioning, and activation of immune cells can contribute to hepatic cell death, inflammation, and fibrogenesis. With disease progression and increasing portal pressure, repeated translocation of bacterial components from the intestinal lumen through the epithelial and vascular barriers leads to persistent mucosal, hepatic, and systemic inflammation which contributes to tissue damage, immune dysfunction, and microbial infection. It is increasingly recognised that innate-like and adaptive T-cell subsets located in the liver, mucosal surfaces, and body cavities play a critical role in the progression of advanced liver disease and inflammatory complications of cirrhosis. Mucosal-associated invariant T cells, natural killer T cells, γδ T cells, and tissue-resident memory T cells in the gut, liver, and ascitic fluid share certain characteristic features, which include that they recognise microbial products, tissue alarmins, cytokines, and stress ligands in tissues, and perform effector functions in chronic liver disease. This review highlights recent advances in the comprehension of human tissue-resident and unconventional T-cell populations and discusses the mechanisms by which they contribute to inflammation, fibrosis, immunosuppression, and antimicrobial surveillance in patients with cirrhosis. Understanding the complex interactions of immune cells in different compartments and their contribution to disease progression will provide further insights for effective diagnostic interventions and novel immunomodulatory strategies in patients with advanced chronic liver disease.

γδ T cells: The potential role in liver disease and implications for cancer immunotherapy

The γδ T cell subset was discovered over 30 years ago, yet continues to be an exciting and challenging component of the adaptive immune response. While γδ T cells represent a very small fraction of all T cells in humans, γδ T cells have a vital effect on human immunity, serving as a bridge between the innate and adaptive immune systems. The characteristics of γδ T cells include recognition of non-MHC restrictive antigens, as well as the ability to secrete an abundance of cytokines, suggesting that γδ T cells have high antitumor activity. As such, they have gained ample attention with respect to tumor immunotherapy in the last decade. The γδ T cell subset comprises up to ∼15-20% of the T-lymphocyte population in the liver, although the liver is recognized as an immune organ with primary immune functions, the role of γδ T cells in liver disease has not been established. Herein, we present a comprehensive overview of molecular mechanisms underlying immune γδ T cell activity in liver disease, including immune liver injury, viral hepatitis, cirrhosis, and hepatocellular carcinoma, and review γδ T cell-based clinical immunotherapeutic approaches.

Characterisation and induction of tissue-resident gamma delta T-cells to target hepatocellular carcinoma

Immunotherapy is now the standard of care for advanced hepatocellular carcinoma (HCC), yet many patients fail to respond. A major unmet goal is the boosting of T-cells with both strong HCC reactivity and the protective advantages of tissue-resident memory T-cells (TRM). Here, we show that higher intratumoural frequencies of γδ T-cells, which have potential for HLA-unrestricted tumour reactivity, associate with enhanced HCC patient survival. We demonstrate that γδ T-cells exhibit bona fide tissue-residency in human liver and HCC, with γδTRM showing no egress from hepatic vasculature, persistence for >10 years and superior anti-tumour cytokine production. The Vγ9Vδ2 T-cell subset is selectively depleted in HCC but can efficiently target HCC cell lines sensitised to accumulate isopentenyl-pyrophosphate by the aminobisphosphonate Zoledronic acid. Aminobisphosphonate-based expansion of peripheral Vγ9Vδ2 T-cells recapitulates a TRM phenotype and boosts cytotoxic potential. Thus, our data suggest more universally effective HCC immunotherapy may be achieved by combining aminobisphosphonates to induce Vγ9Vδ2TRM capable of replenishing the depleted pool, with additional intratumoural delivery to sensitise HCC to Vγ9Vδ2TRM-based targeting.

The Agonists of Peroxisome Proliferator-Activated Receptor-γ for Liver Fibrosis

Liver fibrosis is a common link in the transformation of acute and chronic liver diseases to cirrhosis. It is of great clinical significance to study the factors associated with the induction of liver fibrosis and elucidate the method of reversal. Peroxisome proliferator-activated receptors (PPARs) are a class of nuclear transcription factors that can be activated by peroxisome proliferators. PPARs play an important role in fibrosis of various organs, especially the liver, by regulating downstream targeted pathways, such as TGF-β, MAPKs, and NF-κB p65. In recent years, the development and screening of PPAR-γ ligands have become a focus of research. The PPAR-γ ligands include synthetic hypolipidemic and antidiabetic drugs. In addition, microRNAs, lncRNAs, circRNAs and nano new drugs have attracted research interest. In this paper, the research progress of PPAR-γ in the pathogenesis and treatment of liver fibrosis was discussed based on the relevant literature in recent years.