Potential therapies for acute-on-chronic liver failure

S100A9/RAGE pathway regulation of mitophagy and the effect of JianPi LiShi YangGan formula in acute-on-chronic liver failure

ETHNOPHARMACOLOGICAL RELEVANCE

Mitophagy regulates cellular homeostasis and liver inflammation; however, it is inhibited in acute-on-chronic liver failure (ACLF), which drives disease progression. The JianPi LiShi YangGan formula (YGF) has the potential to improve inflammatory responses and reduce mortality in patients with ACLF. However, the precise mechanisms underlying these effects remain unknown.

AIM OF THE STUDY

We investigated the role of S100A9/RAGE signaling in mitophagy and the protective effects of traditional Chinese medicinal compounds on ACLF.

MATERIALS AND METHODS

An ACLF mouse model was established using carbon tetrachloride, lipopolysaccharide, and d-galactose. Hematoxylin and eosin staining and enzyme-linked immunosorbent assay were employed to evaluate the hepatoprotective effect of YGF in ACLF mice. Mitochondrial damage was assessed using transmission electron microscopy. Protein levels of mitophagy-related indicators were assessed through immunohistochemistry and western blotting, and immunofluorescence staining was performed to observe Lamp2 and COX-IV co-localization.

RESULTS

The hepatocytes of ACLF mice contained damaged mitochondria, decreased mitophagy-related protein (Pink1, Parkin, and LC3B) expression and activated S100A9/RAGE signaling. Inhibiting S100A9 or RAGE improved liver injury in ACLF mice and enhanced Lamp2-COX-IV co-localization. In alpha mouse liver 12 (AML12) cells overexpressing RAGE, recombinant S100A9 protein inhibited mitophagy induced by 3-chlorocarbonyl benzoyl chloride. YGF reduced mitochondrial damage, increased Pink1, Parkin, and LC3B levels, and enhanced mitophagy while inhibiting S100A9/RAGE activation in the hepatocytes of ACLF mice.

CONCLUSIONS

This study found that S100A9/RAGE pathway activation impairs mitophagy, and YGF alleviates liver injury by downregulating S100A9 and RAGE signaling, which may be a novel therapeutic strategy for ACLF.

Beyond the Limits of Conventional Coagulation Tests: A Comprehensive Overview of ACLF-Related Coagulopathies

Acute-on-chronic liver failure (ACLF) is a complex and severe condition marked by multiple organ failure and high short-term mortality. Coagulopathy, a key component of ACLF, is characterized by rebalanced hemostasis with both hypo- and hypercoagulable features, increasing the risk of bleeding and thrombosis. Conventional coagulation tests, including prothrombin time (PT) and platelet count, fail to fully capture the complexity of coagulation dysfunction in ACLF. Advanced diagnostic tools, like viscoelastic tests (VETs), offer a more comprehensive assessment, yet they remain limited in evaluating endothelial dysfunction and fail to account for reduced levels of anticoagulant factors. Emerging therapeutic strategies targeting coagulopathies in ACLF hold promise, but their clinical efficacy remains unclear. A more nuanced approach to diagnosing and managing coagulopathy in ACLF is needed, incorporating advanced hemostatic profiling to better inform prognosis and guide treatment decisions.

Acute-on-Chronic Liver Failure: Steps Towards Consensus

Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized by organ failure and high short-term mortality. Since its first definition in 2013, many international organizations have defined this syndrome and, till now, there has been no agreement regarding definitions and diagnostic criteria. Although the precise mechanism of ACLF is unknown, precipitant factors and the systemic inflammation response play a major role. Specific management of this high-mortality syndrome is still under development, but a general consensus in the diagnosis and management of ACLF is needed.

Mechanisms and treatment approaches for ACLF

Acute-on-chronic liver failure (ACLF) is a life-threatening syndrome characterized by decompensation of cirrhosis, severe systemic inflammation and organ failures. ACLF is frequently triggered by intra- and/or extrahepatic insults, such as bacterial infections, alcohol-related hepatitis or flares of hepatic viruses. The imbalance between systemic inflammation and immune tolerance causes organ failures through the following mechanisms: (i) direct damage of immune cells/mediators; (ii) worsening of circulatory dysfunction resulting in organ hypoperfusion and (iii) metabolic alterations with prioritization of energetic substrates for inflammation and peripheral organ 'energetic crisis'. Currently, the management of ACLF includes the support of organ failures, the identification and treatment of precipitating factors and expedited assessment for liver transplantation (LT). Early LT should be considered in patients with ACLF grade 3, who are unlikely to recover with the available treatments and have a mortality rate > 70% at 28 days. However, the selection of transplant candidates and their prioritization on the LT waiting list need standardization. Future challenges in the ACLF field include a better understanding of pathophysiological mechanisms leading to inflammation and organ failures, the development of specific treatments for the disease and personalized treatment approaches. Herein, we reviewed the current knowledge and future perspectives on mechanisms and treatment of ACLF.

Liver transplantation for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) occurs in the context of advanced liver disease and is associated with hepatic and extrahepatic organ failure, eventually leading to a major risk of short-term mortality. To date, there are very few effective therapeutic options for ACLF. In many cases, liver transplantation is the only life-saving treatment that has acceptable outcomes in carefully selected recipients. This Review addresses key aspects of the use of liver transplantation for patients with ACLF, providing an in-depth discussion of existing evidence regarding candidate selection, the optimal window for transplantation, potential prioritisation of liver grafts for this indication, and the global management of ACLF to bridge patients to liver transplantation.

Acute decompensation of cirrhosis versus acute-on-chronic liver failure: What are the clinical implications?

It is essential to identify the subgroup of patients who experience poorer outcomes in order to adapt clinical management effectively. In the context of liver disease, the earlier the identification occurs, the greater the range of therapeutic options that can be offered to patients. In the past, patients with acute decompensation (AD) of chronic liver disease were treated as a homogeneous group, with emphasis on identifying those at the highest risk of death. In the last 15 years, a differentiation has emerged between acute-on-chronic liver failure syndrome (ACLF) and AD, primarily due to indications that the latter is linked to a less favorable short-term prognosis. Nevertheless, the definition of ACLF varies among the different knowledge societies, making it challenging to assess its true impact compared with AD. Therefore, the purpose of this review is to provide a detailed analysis emphasizing the critical importance of identifying ACLF in the field of advanced liver disease. We will discuss the differences between Eastern and Western approaches, particularly in relation to the occurrence of liver failure and disease onset. Common characteristics, such as the dynamic nature of the disease course, will be highlighted. Finally, we will focus on two key clinical implications arising from these considerations: the prevention of ACLF before its onset and the clinical management strategies once it develops, including liver transplantation and withdrawal of care.

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.

IGF2BP3/HIF1A/YAP signaling plays a role in driving acute-on-chronic liver failure through activating hepatocyte reprogramming

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a syndrome with both high prevalence and mortality. However, the underlying mechanisms remain elusive and there is no effective therapeutic approach available. Here we aim to uncover novel molecular mechanisms of ACLF and identify potential therapeutic targets.

METHOD

We performed integrative analysis of 3 transcriptomic datasets and subsequent bioinformatic analysis aiming for potential genes of significance in ACLF development, identifying a critical role of IGF2BP3/HIF1A signaling in development of ACLF. Expression of molecules in IGF2BP3/HIF1A pathway and hepatocyte reprogramming markers in clinical samples were then determined by western blot and quantitative PCR. N6-methyladenosine (m6A) RNA modification of HIF1A was analyzed by m6A dot assay and PCR following m6A-antibody precipitation. The molecular mechanisms among IGFBP3, HIF1α and YAP1 were further validated by gene overexpression and knockdown experiments in HepG2 and Hep3B cells. Cell phenotypes of hepatocyte reprogramming were determined by EdU staining, sphere formation assay and immunoblotting of relevant markers.

RESULTS

Our data demonstrated that IGF2BP3 recognized m6A modification in HIF1A mRNA as an m6A reader, thereby promoting expression of HIF1A by increasing RNA stability. HIF1A activated Rho GTPases (RhoA) and suppressed phosphorylation of YAP via inhibiting LATS1/2, promoting translocation of non-phosphorylated YAP into the nucleus, resulting in fetal liver programme and ultimate hepatic injury in ACLF patients.

CONCLUSION

We reveal a novel molecular mechanism that IGF2BP3/HIF1A/YAP signaling promotes hepatocyte reprogramming, causing hepatic injury in ACLF. Our study provides potential targets for treatment of ACLF.