Establishment of a murine model of acute-on-chronic liver failure with multi-organ dysfunction

Uridine diphosphate glucuronosyltransferase 1A1 prevents the progression of liver injury

BACKGROUND

Uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) plays a crucial role in metabolizing and detoxifying endogenous and exogenous substances. However, its contribution to the progression of liver damage remains unclear.

AIM

To determine the role and mechanism of UGT1A1 in liver damage progression.

METHODS

We investigated the relationship between UGT1A1 expression and liver injury through clinical research. Additionally, the impact and mechanism of UGT1A1 on the progression of liver injury was analyzed through a mouse model study.

RESULTS

Patients with UGT1A1 gene mutations showed varying degrees of liver damage, while patients with acute-on-chronic liver failure (ACLF) exhibited relatively reduced levels of UGT1A1 protein in the liver as compared to patients with chronic hepatitis. This suggests that low UGT1A1 levels may be associated with the progression of liver damage. In mouse models of liver injury induced by carbon tetrachloride (CCl4) and concanavalin A (ConA), the hepatic levels of UGT1A1 protein were found to be increased. In mice with lipopolysaccharide or liver steatosis-mediated liver-injury progression, the hepatic protein levels of UGT1A1 were decreased, which is consistent with the observations in patients with ACLF. UGT1A1 knockout exacerbated CCl4- and ConA-induced liver injury, hepatocyte apoptosis and necroptosis in mice, intensified hepatocyte endoplasmic reticulum (ER) stress and oxidative stress, and disrupted lipid metabolism.

CONCLUSION

UGT1A1 is upregulated as a compensatory response during liver injury, and interference with this upregulation process may worsen liver injury. UGT1A1 reduces ER stress, oxidative stress, and lipid metabolism disorder, thereby mitigating hepatocyte apoptosis and necroptosis.

Protective effect of continuous blood purification on liver, kidney, and intestinal function in rats with oral carbon tetrachloride poisoning

BACKGROUND

Carbon tetrachloride (CCl₄) poisoning is a common type of poisoning in chemical workers, but there is no specific clinical drug available to treat liver, kidney, and intestinal injuries caused by this kind of poisoning.

AIM

To explore the protective effect of continuous blood purification (CBP) on liver, kidney, and intestinal function in rats with oral CCl₄ poisoning and the potential mechanism involved.

METHODS

Sprague-Dawley rats were divided into control group, model group (CCl₄), and CBP treatment group (CCl₄ + CBP). The rat model was established by gavage of CCl₄. Peripheral blood samples were collected to detect the number of white blood cells and neutrophils, and the levels of blood urea nitrogen (BUN), creatinine (Cr), C-reactive protein (CRP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), D-lactic acid (D-LA), intestinal fatty acid binding protein (I-FABP), and procalcitonin (PCT). Liver, kidney, and intestinal tissues were collected for pathological examination, and the relative protein expression level of nuclear transcription factor-κB (NF-κB) pathway molecules was detected by immunohistochemistry and Western blot.

RESULTS

CBP treatment significantly reduced the increase of white blood cell and neutrophil counts (P < 0.05) and the increase of serum BUN, Cr, CRP, ALT, AST, D-LA, I-FABP and PCT (P < 0.05) induced by CCl₄. CBP treatment also reduced the expression of neutrophil gelatinase-associated lipocalin in kidney tissue and the pathological changes in the liver, kidney, and intestine. Immunohistochemistry and Western blot showed that CBP treatment could reduce the activation of the NF-κB pathway induced by CCl₄ (P < 0.05).

CONCLUSION

CBP has a protective effect against liver, kidney, and intestinal injuries induced by CCl₄, and it may improve the symptoms of liver, kidney, and intestinal injuries by reducing the activation of the NF-κB pathway induced by CCl₄.

Sepsis-induced endothelial dysfunction drives acute-on-chronic liver failure through Angiopoietin-2-HGF-C/EBPβ pathway

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is an acute liver and multisystem failure in patients with previously stable cirrhosis. A common cause of ACLF is sepsis secondary to bacterial infection. Sepsis-associated ACLF involves a loss of differentiated liver function in the absence of direct liver injury, and its mechanism is unknown. We aimed to study the mechanism of sepsis-associated ACLF using a novel mouse model.

APPROACH AND RESULTS

Sepsis-associated ACLF was induced by cecal ligation and puncture procedure (CLP) in mice treated with thioacetamide (TAA). The combination of TAA and CLP resulted in a significant decrease in liver synthetic function and high mortality. These changes were associated with reduced metabolic gene expression and increased CCAAT enhancer binding protein beta (C/EBPβ) transcriptional activity. We found that C/EBPβ binding to its target gene promoters was increased. In humans, C/EBPβ chromatin binding was similarly increased in the ACLF group compared with control cirrhosis. Hepatocyte-specific Cebpb knockout mice had reduced mortality and increased gene expression of hepatocyte differentiation markers in TAA/CLP mice, suggesting that C/EBPβ promotes liver failure in these mice. C/EBPβ activation was associated with endothelial dysfunction, characterized by reduced Angiopoietin-1/Angiopoietin-2 ratio and increased endothelial production of HGF. Angiopoietin-1 supplementation or Hgf knockdown reduced hepatocyte C/EBPβ accumulation, restored liver function, and reduced mortality, suggesting that endothelial dysfunction induced by sepsis drives ACLF through HGF-C/EBPβ pathway.

CONCLUSIONS

The transcription factor C/EBPβ is activated in both mouse and human ACLF and is a potential therapeutic target to prevent liver failure in patients with sepsis and cirrhosis.

Downregulated VISTA enhances Th17 differentiation and aggravates inflammation in patients with acute-on-chronic liver failure

BACKGROUND AND AIMS

Persistent inflammatory response and immune activation are the core mechanisms underlying acute-on-chronic liver failure (ACLF). Previous studies have shown that deficiency of V-type immunoglobulin domain-containing suppressor of T-cell activation (VISTA) exacerbates the progression of inflammatory diseases. We aimed to clarify the role of VISTA in the pathogenesis of ACLF.

METHODS

Blood and liver samples were collected from healthy subjects, stable cirrhosis, and ACLF patients to characterize VISTA expression and function. An ACLF mouse model was used to ascertain potential benefits of anti-VISTA monoclonal antibody (mAb) treatment.

RESULTS

VISTA expression was significantly reduced in the naïve and central memory CD4+ T cells from patients with ACLF. The expression of VISTA on CD4+ T cells was associated with disease severity and prognosis. VISTA downregulation contributed to the activation and proliferation of CD4+ T cells and enhanced the differentiation of T helper 17 cells (Th17) and secretion of inflammatory cytokines through the activated Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling pathway. Moreover, agonistic anti-VISTA mAb treatment inhibited the activation and cytokine production of CD4+ T cells and reduced mortality and liver inflammation of the ACLF mice.

CONCLUSIONS

The decreased expression of VISTA may facilitate development of Th17 cells and promote the progression of inflammation in ACLF patients. These findings are helpful for elucidating the pathogenesis of ACLF and for the identification of new drug targets.

Liver Regeneration in Acute on Chronic Liver Failure

Liver regeneration is a multifaceted process by which the organ regains its original size and histologic organization. In recent decades, substantial advances have been made in our understanding of the mechanisms underlying regeneration following loss of hepatic mass. Liver regeneration in acute liver failure possesses several classic pathways, while also exhibiting unique differences in key processes such as the roles of differentiated cells and stem cell analogs. Here we summarize these unique differences and new molecular mechanisms involving the gut-liver axis, immunomodulation, and microRNAs with an emphasis on applications to the patient population through stem cell therapies and prognostication.

The progress to establish optimal animal models for the study of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) defines a complicated and multifaceted syndrome characterized by acute liver dysfunction following an acute insult on the basis of chronic liver diseases. It is usually concurrent with bacterial infection and multi-organ failure resulting in high short-term mortality. Based on the cohort studies in ACLF worldwide, the clinical course of ACLF was demonstrated to comprise three major stages including chronic liver injury, acute hepatic/extrahepatic insult, and systemic inflammatory response caused by over-reactive immune system especially bacterial infection. However, due to the lack of optimal experimental animal models for ACLF, the progress of basic study on ACLF is limping. Though several experimental ACLF models were established, none of them can recapitulate and simulate the whole pathological process of ACLF patients. Recently, we have developed a novel mouse model for ACLF combining chronic liver injury [injection of carbon tetrachloride (CCl₄) for 8 weeks], acute hepatic insult (injection of a double dose CCl₄), and bacterial infection (intraperitoneal injection of Klebsiella pneumoniae), which could recapitulate the major clinical features of patients with ACLF worsened by bacterial infection.

Prospect of Animal Models for Acute-on-chronic Liver Failure: A Mini-review

Acute-on-chronic liver failure (ACLF) is a clinical syndrome that develops in patients with chronic liver diseases following a precipitating event and associated with a high mortality rate due to systemic multiorgan failure. Establishing a suitable and stable animal model to precisely elucidate the molecular basis of ACLF pathogenesis is essential for the development of effective early diagnostic and treatment strategies. In this context, this article provides a concise and inclusive review of breakthroughs in ACLF animal model development.

Acute-on-chronic liver failure (ACLF) in 2022: have novel treatment paradigms already arrived?

INTRODUCTION

Acute-on-chronic failure (ACLF) is a recognized syndrome in patients with chronic liver disease and is characterized by acute decompensation, organ failure(s), and a high short-term mortality. ACLF is often triggered by ongoing alcohol consumption, gastrointestinal bleeding and/or infections, and is pathophysiologically characterized by uncontrolled systemic inflammation coupled with paradoxical immunoparesis. Patients with ACLF require prompt and early recognition. Management requires extensive utilization of clinical resources often including escalation to intensive care.

AREAS COVERED

Currently, there are no specific targeted treatments for established ACLF, and management revolves around treating underlying precipitants and providing organ support. In this article, we review the epidemiology and pathophysiology of ACLF and summarize recent advances in management strategies of this syndrome, focusing specifically on novel emerging therapies.

EXPERT COMMENTARY

ACLF is a challenging condition with rapid clinical course, high short-term mortality and varying clinical phenotypes. Management of ACLF is broadly focused on supportive care often in an intensive care setting with liver transplantation proving to be an increasingly relevant and effective rescue therapy. This disease has clear pathogenesis and epidemiological burden, thus distinguishing it from decompensated cirrhosis; there is clear clinical need for the development of specific and nuanced therapies to treat this condition.

Plasma Interleukin-6 Level: A Potential Prognostic Indicator of Emergent HBV-Associated ACLF

OBJECTIVE

To identify markers that predict the progression to hepatitis B virus-associated acute-on-chronic liver failure (HBV-ACLF).

METHODS

We recruited 125 patients with chronic hepatitis B (CHB) between September 2013 and March 2017. During hospitalization, 25 patients progressed to LF and were classified as the LF group, while the remaining 100 patients were classified as the non-LF (NLF) group. We compared the kinetic changes in clinical and immune indicators including age, total bilirubin level, prothrombin time, model for end-stage liver disease score, interleukin (IL)-6, IL-8, and IL-10 cytokine levels, and number of T helper 17 and regulatory T cells between groups to determine their association with progression to HBV-ACLF. The prognostic value of clinical and immune indicators was determined using the area under the receiver operating characteristic curve (AUC) value.

RESULTS

Cox regression analysis suggested that the plasma IL-6 level could predict CHB progression to HBV-ACLF (relative risk = 1.082, 95% confidence interval: 1.006-1.164; P=0.034). The AUC value, sensitivity, and specificity of baseline IL-6 level for predicting HBV-ACLF were 82.63%, 83.3%, and 82.9%, respectively (P=0.001).

CONCLUSION

A high plasma IL-6 level in CHB patients could be an early biomarker for HBV-ACLF.