Mechanisms and aetiology-dependent treatment of acute liver failure

Therapeutic effect of hUC-MSCs from different transplantation routes on acute liver failure in rats

Objective

Acute liver failure (ALF) is a rare yet serious clinical syndrome. Recent studies have indicated that stem cells can effectively treat this condition. However, the optimal route for stem cell transplantation in the treatment of ALF remains unclear. This study aims to investigate the most effective transplantation route for stem cell therapy in ALF.

Methods

Human umbilical cord mesenchymal stem cells (hUC-MSCs) expressing both luciferase and green fluorescent protein were generated using a lentiviral vector. The hUC-MSCs were transplanted via the tail vein, portal vein, and abdominal cavity. The survival and distribution of the transplanted hUC-MSCs in rats were assessed through in vivo imaging and immunofluorescence. Furthermore, the therapeutic effects of hUC-MSCs transplanted via different routes on ALF were compared.

Results

The survival time of hUC-MSCs transplanted via the tail vein and portal vein was shorter compared to those transplanted intraperitoneally. The distribution of hUC-MSCs varied by transplantation route: those injected via the tail vein and portal vein were primarily found in the lungs and liver, respectively, while intraperitoneally transplanted hUC-MSCs predominantly localized in the abdominal cavity. In ALF rats, hUC-MSCs transplanted via the tail vein and portal vein improved survival rates, enhanced liver pathology, and reduced levels of inflammatory cytokines in liver tissue. In contrast, abdominal transplantation of hUC-MSCs showed no significant therapeutic effect.

Conclusion

hUC-MSCs transplanted via the tail vein and portal vein exhibited similar therapeutic effects on ALF; however, abdominal transplantation of hUC-MSCs showed no significant effect.

Overview of ferroptosis and pyroptosis in acute liver failure

In this editorial, we comment on the article by Zhou et al published in a recent issue. We specifically focus on the crucial roles of ferroptosis and pyroptosis in acute liver failure (ALF), a disease with high mortality rates. Ferroptosis is the result of increased intracellular reactive oxygen species due to iron accumulation, glutathione (GSH) depletion, and decreased GSH peroxidase 4 activity, while pyroptosis is a procedural cell death mediated by gasdermin D which initiates a sustained inflammatory process. In this review, we describe the characteristics of ferroptosis and pyroptosis, and discuss the involvement of the two cell death modes in the onset and development of ALF. Furthermore, we summarize several interfering methods from the perspective of ferroptosis and pyroptosis for the alleviation of ALF. These observations might provide new targets and a theoretical basis for the treatment of ALF, which are also crucial for improving the prognosis of patients with ALF.

Med1 inhibits ferroptosis and alleviates liver injury in acute liver failure via Nrf2 activation

BACKGROUND

Extensive hepatocyte mortality and the absence of specific medical therapy significantly contribute to the unfavorable prognosis of acute liver failure (ALF). Ferroptosis is a crucial form of cell death involved in ALF. In this study, we aimed to determine the impact of Mediator complex subunit 1 (Med1) on ferroptosis and its potential hepatoprotective effects in ALF.

RESULTS

Med1 expression is diminished in the liver of lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced ALF mice, as well as in hepatocytes damaged by H2O2 or TNF-α/D-GalN in vitro. Med1 overexpression mitigates liver injury and decreases the mortality rate of ALF mice by ferroptosis inhibition. The mechanism by which Med1 inhibits erastin-induced ferroptosis in hepatocytes involves the upregulation of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant genes heme oxygenase-1 (HO-1), glutamate cysteine ligase catalytic (GCLC), and NAD(P)H quinone oxidoreductase 1 (NQO1). Furthermore, Med1 overexpression suppresses the transcription of proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the liver of mice with LPS/D-GalN-induced ALF.

CONCLUSION

Overall, our research findings indicate that Med1 suppresses ferroptosis and alleviates liver injury in LPS/D-GalN-induced ALF through the activation of Nrf2. These findings substantiate the therapeutic viability of targeting the Med1-Nrf2 axis as a means of treating individuals afflicted with ALF.

New advances in the study of PD-1/PD-L1 inhibitors-induced liver injury

The application of immune checkpoint inhibitors (ICIs) has made extraordinary achievements in tumor treatment. Among them, programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors can improve the prognosis of advanced tumors, and have been widely used in clinical practice to treat many types of cancers. However, excessive immune response can also induce immune-related adverse events (irAEs) involving many organs. Of these, immune-related liver injury is the relatively common and carries the highest morbidity, which has attracted the attention of hepatologists all over the world. The incidence of this type of liver injury depends specifically on factors such as the type of drug being combined, viral infection, type of cancer and liver transplantation. Although there is no unanimity on the mechanism of PD-1/PD-L1 inhibitor-induced liver injury, in this review, we also summarize the current evidence that provides insights into the pathogenesis of PD-1/PD-L1 inhibitor-induced liver injury, including the fact that PD-1/PD-L1 inhibitors cause reactivation of CTLs, aberrant presentation of autoantigens, hepatic immune tolerance environment is disrupted, and cytokine secretion, among other effects. Patients usually develop liver injury after the use of PD-1/PD-L1 inhibitors, and clinical symptoms mainly include weakness, muscle pain, nausea and vomiting, and jaundice. Histologically, the main manifestation is lobular hepatitis with lobular inflammatory infiltration. Since the specific biomarkers for PD-1/PD-L1 inhibitor-associated liver injury have not been identified yet, alpha-fetoprotein, IL-6, and IL-33 have the potential to be biomarkers for predicting this type of liver injury in the future, but this requires further research. We also describe the examination and treatment of this type of liver injury, which usually includes eliminating related influencing factors, regularly monitoring liver function, temporarily retaining or permanently stopping ICIs treatment according to the severity of toxicity, and using corticosteroids. This review may provide useful information for the future clinical practice of PD-1/PD-L1 inhibitors.