sTim-3 alleviates liver injury via regulation of the immunity microenvironment and autophagy

Hepatoprotective efficacy and interventional mechanism of JianPi LiShi YangGan formula in acute-on-chronic liver failure

ETHNOPHARMACOLOGICAL RELEVANCE

Acute-on-chronic liver failure (ACLF) progresses rapidly with a high short-term death rate. Although JianPi LiShi YangGan formula (YGF) has been used to treat ACLF by managing inflammatory responses and reducing endotoxemia, hepatocyte injury, and mortality, the underlying mechanisms remain unclear.

AIM OF THE STUDY

This study aims to investigate the potential mechanisms underlying the efficacy and protective benefits of YGF in mice with ACLF.

MATERIALS AND METHODS

YGF composition was determined using high-performance liquid chromatography coupled with mass spectrometry. We constructed a mouse model of ACLF using carbon tetrachloride, lipopolysaccharide (LPS), and D-galactosamine (D-Gal), as well as an in vitro model of D-Gal/LPS-induced hepatocyte injury. The therapeutic effects of YGF in ACLF mice were verified using hematoxylin-eosin, Sirius red, and Masson staining, and by measuring serum alanine transaminase (ALT), aspartate transaminase (AST), and inflammatory cytokine levels. Mitochondrial damage in hepatocytes was evaluated using electron microscopy, while superoxide anion levels in liver tissue were investigated using dihydroethidium. Transcriptome analysis, immunohistochemistry, western blotting, and immunofluorescence assays were performed to explore the mechanisms underlying the ameliorative effects of YGF against ACLF.

RESULTS

In mice with ACLF, YGF therapy partially decreased serum inflammatory cytokine levels, as well as hepatocyte injury and liver fibrosis. The livers of ACLF mice treated with YGF exhibited decreased mitochondrial damage and reactive oxygen species generation, as well as a decreased number of M1 macrophages and increased number of M2 macrophages. Transcriptome analysis revealed that YGF may regulate biological processes such as autophagy, mitophagy, and PI3K/AKT signaling. In ACLF mice, YGF promoted mitophagy and inhibited PI3K/AKT/mTOR pathway activation in hepatocytes. Meanwhile, the autophagy inhibitor 3M-A reduced the capacity of YGF to induce autophagy and protect against hepatocyte injury in vitro. In contrast, the PI3K agonist 740 Y-P suppressed the ability of YGF to control PI3K/AKT/mTOR pathway activation and induce autophagy.

CONCLUSIONS

Together, our findings suggest that YGF mediates autophagy, tight junctions, cytokine generation, and other biological processes. In addition, YGF inhibits hepatic inflammatory responses and ameliorates hepatocyte injury in mice with ACLF. Mechanistically, YGF can promote mitophagy to ameliorate acute-on-chronic liver failure by inhibiting the PI3K/AKT/mTOR pathway.

Autophagy in hepatic macrophages can be regulator and potential therapeutic target of liver diseases: A review

Hepatic macrophages are a complex population of cells that play an important role in the normal functioning of the liver and in liver diseases. Autophagy, as a maintainer of cellular homeostasis, is closely connected to many liver diseases. And its roles are not always beneficial, but manifesting as a double-edged sword. The polarization of macrophages and the activation of inflammasomes are mediated by intracellular and extracellular signals, respectively, and are important ways for macrophages to take part in a variety of liver diseases. More attention should be paid to autophagy of hepatic macrophages in liver diseases. In this review, we focus on the regulatory role of hepatic macrophages' autophagy in a variety of liver diseases; especially on the upstream regulator of polarization and inflammasomes activation of the hepatic macrophages. We believe that the autophagy of hepatic macrophages can become a potential therapeutic target for management of liver diseases.

The Immune Pathogenesis of Acute-On-Chronic Liver Failure and the Danger Hypothesis

Acute-on-chronic liver failure (ACLF) is a group of clinical syndromes related to severe acute liver function impairment and multiple-organ failure caused by various acute triggering factors on the basis of chronic liver disease. Due to its severe condition, rapid progression, and high mortality, it has received increasing attention. Recent studies have shown that the pathogenesis of ACLF mainly includes direct injury and immune injury. In immune injury, cytotoxic T lymphocytes (CTLs), dendritic cells (DCs), and CD4⁺ T cells accumulate in the liver tissue, secrete a variety of proinflammatory cytokines and chemokines, and recruit more immune cells to the liver, resulting in immune damage to the liver tissue, massive hepatocyte necrosis, and liver failure, but the key molecules and signaling pathways remain unclear. The “danger hypothesis” holds that in addition to the need for antigens, damage-associated molecular patterns (DAMPs) also play a very important role in the occurrence of the immune response, and this hypothesis is related to the pathogenesis of ACLF. Here, the research status and development trend of ACLF, as well as the mechanism of action and research progress on various DAMPs in ACLF, are summarized to identify biomarkers that can predict the occurrence and development of diseases or the prognosis of patients at an early stage.

Ginsenoside Rb1 alleviates liver injury induced by 3-chloro-1,2-propanediol by stimulating autophagic flux

In recent years, foodborne pollutants have become a hot issue in the field of food safety. 3-chloro-1,2-propanediol (3-MCPD) is a widely existing food contaminant. In our previous study, it was confirmed that 3-MCPD can block autophagic flux by inhibiting lysosomal function, thus causing liver injury. Ginseng is a traditional Chinese herbal medicine that contains a variety of bioactive ingredients, among which ginsenoside Rb1 (Gs-Rb1) is the most abundant. In this study, we aim to use Gs-Rb1 to improve 3-MCPD-induced autophagic flux blockage to alleviate liver injury. First, a nontoxic dose of Gs-Rb1 was identified by screening with the MTT method in which Gs-Rb1was added to HepG2 cells and co-treated with 3-MCPD. We found that Gs-Rb1 effectively enhanced the cell activity inhibited by 3-MCPD. Meanwhile, apoptosis data showed that Gs-Rb1 significantly alleviated the apoptosis of HepG2 cells induced by 3-MCPD. Subsequently, we found that Gs-Rb1 could alleviate autophagic flux blockage caused by 3-MCPD in a dose-dependent manner by detecting autophagy-related protein levels and transfecting mRFP-GFP-LC3 adenovirus. On this basis, we used Western blotting and qPCR to explore whether miR-128 was involved in the alleviation effect of Gs-Rb1 on autophagic flux blockade induced by 3-MCPD. The results showed that Gs-Rb1 inhibited the expression of miR-128 and promoted the nuclear expression and target gene transcription of TFEB. Finally, the findings were confirmed by using a hsa-miR-128 inhibitor and mimic. We found that hsa-miR-128 inhibitor alleviated the autophagic flux blockage and apoptosis caused by 3-MCPD and Gs-Rb1 also had a certain alleviation effect on the autophagic flux blockage and apoptosis caused by hsa-miR-128 mimic. This study elaborated the mechanism by which Gs-Rb1 alleviates hepatotoxicity induced by foodborne 3-MCPD by stimulating autophagic flux via miR-128-targeted TFEB, which provides a reliable theoretical basis and target for the use of natural substances to reduce the harm of food processing pollutants on the human body. PRACTICAL APPLICATION: We found that natural ginsenoside Rb1 can alleviate liver injury induced by 3-MCPD(a toxic substance found in foods such as refined vegetable oil, soy sauce, and baby milk powder), which is conducive to the development and utilization of ginseng and has practical significance for the prevention of foodborne liver injury.

The mitochondria-targeting antioxidant MitoQ alleviated lipopolysaccharide/ d-galactosamine-induced acute liver injury in mice

The mitochondria are the primary source of reactive oxygen species (ROS) under pathological condition, but the significance of mitochondrial ROS in the development of Lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced acute liver injury remains unclear. In the present study, the level of mitochondrial ROS in LPS/D-Gal has been determined by MitoSox staining and the potential roles of mitochondrial ROS in LPS/D-Gal-induced liver injury have been investigated by using the mitochondria-targeting antioxidant MitoQ. The results indicated that LPS/D-Gal exposure induced the generation of mitochondrial ROS while treatment with MitoQ reduced the level of mitochondrial ROS. Treatment with MitoQ ameliorated LPS/D-Gal-induced histopathologic abnormalities, suppressed the elevation of AST and ALT, and increased the survival rate of the experimental animals. Treatment with MitoQ also suppressed LPS/D-Gal-induced production of tumor necrosis factor α (TNF-α), inhibited the activities of caspase-3, caspase-8 and caspase-9, decreased the level of cleaved caspase-3 and reduced the counts of TUNEL positive cells. These results indicate that mitochondrial ROS is involved in the development of LPS-induced acute liver injury and the mitochondria-targeting antioxidant MitoQ might have potential value for the treatment of inflammation-based acute liver injury.