Invariant natural killer T cells: Not to be ignored in liver disease

Immune microenvironment changes of liver cirrhosis: emerging role of mesenchymal stromal cells

Cirrhosis is a progressive and diffuse liver disease characterized by liver tissue fibrosis and impaired liver function. This condition is brought about by several factors, including chronic hepatitis, hepatic steatosis, alcohol abuse, and other immunological injuries. The pathogenesis of liver cirrhosis is a complex process that involves the interaction of various immune cells and cytokines, which work together to create the hepatic homeostasis imbalance in the liver. Some studies have indicated that alterations in the immune microenvironment of liver cirrhosis are closely linked to the development and prognosis of the disease. The noteworthy function of mesenchymal stem cells and their paracrine secretion lies in their ability to promote the production of cytokines, which in turn enhance the self-repairing capabilities of tissues. The objective of this review is to provide a summary of the alterations in liver homeostasis and to discuss intercellular communication within the organ. Recent research on MSCs is yielding a blueprint for cell typing and biomarker immunoregulation. Hopefully, as MSCs researches continue to progress, novel therapeutic approaches will emerge to address cirrhosis.

T lymphocyte-mediated pyroptosis: A new regulatory mechanism in non-viral liver disease

T lymphocyte-mediated pyroptosis plays an important role in the development of non-viral liver diseases. Pyroptosis as a programmed cell death process, has been a hot topic of research on disease pathogenesis in recent years. As one of the most common immune cells in the body, T cells are the major players in adaptive immunity. An increasing number of studies have shown that T lymphocyte-mediated pyroptosis functions in non-viral liver diseases to regulate immune function, alter the immune microenvironment, and thus influence disease progression. These findings will guide us and provide new ideas for the development of subsequent therapeutic agents for non-viral liver diseases.

Crosstalk Between Autophagy and Innate Immunity: A Pivotal Role in Hepatic Fibrosis

Liver fibrosis is a repair process of chronic liver injuries induced by toxic substances, pathogens, and inflammation, which exhibits a feature such as deposition of the extracellular matrix. The initiation and progression of liver fibrosis heavily relies on excessive activation of hepatic stellate cells (HSCs). The activated HSCs express different kinds of chemokine receptors to further promote matrix remodulation. The long-term progression of liver fibrosis will contribute to dysfunction of the liver and ultimately cause hepatocellular carcinoma. The liver also has abundant innate immune cells, including DCs, NK cells, NKT cells, neutrophils, and Kupffer cells, which conduct complicated functions to activation and expansion of HSCs and liver fibrosis. Autophagy is one specific type of cell death, by which the aberrantly expressed protein and damaged organelles are transferred to lysosomes for further degradation, playing a crucial role in cellular homeostasis. Autophagy is also important to innate immune cells in various aspects. The previous studies have shown that dysfunction of autophagy in hepatic immune cells can result in the initiation and progression of inflammation in the liver, directly or indirectly causing activation of HSCs, which ultimately accelerate liver fibrosis. Given the crosstalk between innate immune cells, autophagy, and fibrosis progression is complicated, and the therapeutic options for liver fibrosis are quite limited, the exploration is essential. Herein, we review the previous studies about the influence of autophagy and innate immunity on liver fibrosis and the molecular mechanism to provide novel insight into the prevention and treatment of liver fibrosis.

Crosstalk between NK cells and hepatic stellate cells in liver fibrosis (Review)

Liver fibrosis is a common pathological process of chronic liver diseases, including viral hepatitis and alcoholic liver disease, and ultimately progresses to irreversible cirrhosis and cancer. Hepatic stellate cells (HSCs) are activated to produce amounts of collagens in response to liver injury, thus triggering the initiation and progression of fibrogenesis. Natural killer (NK) cells serve as the essential component of hepatic innate immunity and are considered to alleviate fibrosis by killing activated HSCs. Current antifibrotic interventions have improved fibrosis, but fail to halt its progression in the advanced stage. Clarifying the interaction between NK cells and HSCs will provide clues to the pathogenesis and potential therapies for advanced liver fibrosis.

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.