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

Efficacy and safety of mesenchymal stem cell therapy in acute on chronic liver failure: a systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND

Acute-on-chronic liver failure has become a serious global health burden, which is characterized by an acute deterioration of liver function, rapidly evolving organ failure, and high short-term mortality in patients with chronic liver disease. The pathogenesis includes extensive hepatic necrosis, which is related to intense systemic inflammation and subsequently causes the inflammatory cytokine storm, resulting in portal hypertension, organ dysfunction, and organ failure. Mesenchymal stem cells can function as seed cells to remodel and repair damaged liver tissues, thus showing potential therapeutic alternatives for patients with chronic liver disease. However, standard treatment protocols for mesenchymal stem cells in acute-on-chronic liver failure patients have not been established.

METHODS

We conducted a detailed search from PubMed/Medline, Web of Science, EMBASE, and Cochrane Library to find randomized controlled trials published before October 23, 2021. We formulated criteria for the literature screening according to the PICOS principle (Population, Intervention, Comparison, Outcome, Study design). Subsequently, the bias risk assessment tool was used to assess the quality of all enrolled studies. Finally, outcome measurements including the model of end-stage liver disease score, albumin, total bilirubin, coagulation function, and aminotransferase were extracted for statistical analysis.

RESULTS

A total of 7 clinical trials were included. The results of enrolled studies indicated that patients with acute-on-chronic liver failure who received mesenchymal stem cells inoculation showed a decreased MELD score in 4 weeks and 24 weeks, compared with counterparts who received conventional treatment. Reciprocally, mesenchymal stem cells inoculation improved the ALB levels in 4 weeks and 24 weeks. For secondary indicators, mesenchymal stem cells treatment significantly reduced INR levels and ALT levels, compared with the control group. Our results showed no significant differences in the incidence of adverse reactions or serious adverse events monitored in patients after mesenchymal stem cells inoculation.

CONCLUSION

This meta-analysis indicated that mesenchymal stem cell infusion is effective and safe in the treatment of patients with acute-on-chronic liver failure. Without increasing the incidence of adverse events or serious adverse events, MSC treatment improved liver function including a decrease in MELD score and an increase in ALB levels in patients with acute-on-chronic liver failure. However, large-cohort randomized controlled trials with longer follow-up periods are required to further confirm our conclusions.

Gasdermin D deletion prevents liver injury and exacerbates extrahepatic damage in a murine model of alcohol-induced ACLF

Background

Gasdermin D (GSDM-D), a key executor of pyroptosis, is increased in various liver diseases and contributes to disease progression. Alcohol induces inflammasome activation and cell death, which are both linked to GSDM-D activation. However, its role in alcohol-induced acute-on-chronic liver failure (ACLF) remains unclear.

Methods

ACLF was induced in GSDM-D-deficient or wild-type (WT) mice by 28-day bile duct ligation surgery plus a single 5 g/kg alcohol binge leading to acute decompensation. Nine hours after the alcohol binge, blood, liver, kidney and cerebellum specimens were collected for analysis.

Results

Active GSDM-D was significantly increased in humans and mice ACLF livers compared with both healthy controls and cirrhotic livers. GSDM-D-deficient mice with ACLF showed decreased inflammation, neutrophil infiltration and fibrosis in the liver, together with a reduction in pyroptotic, apoptotic and necroptotic death, compared with WT ACLF mice. Notably, GSDM-D-deficient mice also showed decreased liver regeneration and hepatocyte function. This was associated with an increase in senescence and expression of stem-like/cholangiocyte markers in the liver. Interestingly, in the kidney, GSDM-D-deficient mice showed an increase in histopathological damage score, decreased function and increased expression of necroptosis-related genes. In the cerebellum, GSDM-D deficiency increased the expression of neuroinflammation markers, astrocyte activation and apoptosis-related genes.

Conclusion

Our data indicate that GSDM-D deficiency has organ-specific effects in ACLF. While it reduces inflammation, neutrophil activation, cell death and fibrosis in the liver, GSDM-D deficiency impairs the synthetic function and increases senescence in hepatocytes. GSDM-D deficiency also increases kidney injury and neuroinflammation in ACLF.

Hepatic and extrahepatic metabolic modulation in hbv-related decompensated cirrhosis and acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) and decompensated cirrhosis (DC) are life-threatening syndromes that can develop at the end-stage of chronic hepatitis B virus (HBV) infection. Both ACLF and DC are complicated by hepatic and extrahepatic pathogeneses. To better understand the compartment-specific metabolic modulations related to their pathogenesis, HBV-DC, HBV-ACLF patients, and controls (30 each) were analyzed by metabolomics using portal (Port), hepatic vein (Hep), and peripheral (Peri) serum. Compartment ratios of metabolites (RatioHep/Port, RatioPeri/Hep, and RatioPort/Peri) were calculated. The liver tissues (10 per group) were analyzed using transcriptomics and metabolomics. An additional 75 patients with ACLF, 20 with DC, and 20 with liver cirrhosis (LC) were used to confirm oxlipid dysregulation. Both multi-omics datasets suggest suppressed energy, amino acid, and pyrimidine metabolism in the ACLF/DC liver. The serum metabolomic variations were contributed primarily by disease rather than sampling compartments, as both HBV-ACLF and HBV-DC patients demonstrated abnormal profiles of amino acids and peptides, indoles, purines, steroids, and benzimidazoles. In ACLF/DC patients, impaired hepatic metabolism resulted in a highly correlated hepatic and portal vein serum metabolome and release of inflammatory lipids and heme metabolites from the liver. HBV-ACLF showed higher RatioPeri/Hep of extrahepatic inflammatory oxlipids, while HBV-DC patients showed higher RatioPort/Peri of gut microbial metabolites. An inflammatory oxlipid outburst was confirmed in the early stages of HBV-ACLF. The inflammatory effects of the selected oxlipids were confirmed in monocytes. These findings support a synergy between liver-specific mechanisms and systemic inflammation in ACLF/DC development, and that pro-inflammatory oxlipids are metabolic signatures of early HBV-ACLF.

Metabolic Dysregulation and Metabolite Imbalances in Acute-on-chronic Liver Failure: Impact on Immune Status

Liver failure encompasses a range of severe clinical syndromes resulting from the deterioration of liver function, triggered by factors both within and outside the liver. While the definition of acute-on-chronic liver failure (ACLF) may vary by region, it is universally recognized for its association with multiorgan failure, a robust inflammatory response, and high short-term mortality rates. Recent advances in metabolomics have provided insights into energy metabolism and metabolite alterations specific to ACLF. Additionally, immunometabolism is increasingly acknowledged as a pivotal mechanism in regulating immune cell functions. Therefore, understanding the energy metabolism pathways involved in ACLF and investigating how metabolite imbalances affect immune cell functionality are crucial for developing effective treatment strategies for ACLF. This review methodically examined the immune and metabolic states of ACLF patients and elucidated how alterations in metabolites impact immune functions, offering novel perspectives for immune regulation and therapeutic management of liver failure.

Pre-treatment with tocilizumab reduces lipopolysaccharide-induced acute lung injury in biliary cirrhotic rats

Infection-related lipopolysaccharide (LPS) release causes cytokine storm and acute lung injury. Emerging data show that the interleukin 6 (IL-6) inhibitor tocilizumab can improve lung damage in patients with sepsis. This study aimed to investigate the therapeutic effect of tocilizumab on acute lung injury in cirrhotic rats. Biliary cirrhosis was induced in Sprague-Dawley rats with common bile duct ligation (BDL). Sham-operated rats served as surgical controls. Tocilizumab was administered on post-operative day 21, and LPS was injected intraperitoneally on day 29. Three hours after LPS injection, hemodynamic parameters, biochemistry data, and arterial blood gas analysis were evaluated, along with measurements of IL-6 and tumor necrosis factor-α (TNF-α). Liver and lung histology was examined, and protein levels were analyzed. LPS administration reduced portal pressure, portal venous flow and cardiac index in the BDL rats. In addition, LPS administration induced acute lung injury, hypoxia and elevated TNF-α and IL-6 levels. Pre-treatment with tocilizumab did not affect hemodynamic and biochemistry data, but it ameliorated lung injury and decreased TNF-α, IL-6, and CD68-positive macrophage infiltration. Moreover, tocilizumab administration improved hypoxia and gas exchange in the BDL rats, and downregulated hepatic and pulmonary inflammatory protein expression. In conclusion, LPS administration induced acute lung injury in biliary cirrhotic rats. Pre-treatment with tocilizumab reduces lung damage and hypoxia, possibly by downregulating inflammatory proteins and reducing IL-6, TNF-α and CD68-positive macrophage recruitment in the lung.

Chishao - Fuzi herbal pair restore the macrophage M1/M2 balance in acute-on-chronic liver failure

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional herbal pair Paeoniae Radix Rubra (roots of Paeonia lactiflora Pall., Chishao in Chinese) and Aconiti Lateralis Radix Praeparata (lateral roots of Aconitum carmichaelii Debeaux, Fuzi in Chinese) are widely used for the treatment of liver diseases, demonstrating clinical efficacy against acute-on-chronic liver failure (ACLF). As the core drug pair representing the "clearing method" and "warming method" in traditional Chinese medicine (TCM), they align with the TCM syndromic characteristics of ACLF, characterized by a mixture of deficiencies and realities. However, the molecular mechanisms underlying the anti-ACLF effects of Chishao - Fuzi herbal pair remain unclear.

AIM OF THE STUDY

To reveal the immunoinflammatory status of patients with hepatitis B virus-related ACLF (HBV-ACLF) based on macrophage polarization and to explore the mechanism of action of Chishao - Fuzi herbal pair in regulating macrophage polarization against ACLF.

MATERIALS AND METHODS

Peripheral blood samples were prospectively obtained from patients with HBV-ACLF, patients with chronic hepatitis B (CHB) in the immunoactive phase and healthy individuals. Flow cytometry, qRT-qPCR, and ELISA were used to reveal the activation status of monocyte-macrophages and the expression differences in related cytokines in the peripheral blood of patients with HBV-ACLF. Then, an ACLF rat model and a macrophage inflammation model in vitro were established. Hematoxylin-eosin staining, immunohistochemical staining, transmission electron microscopy, flow cytometry, western blotting, RT-qPCR, and ELISA were used to observe changes in the expression of M1/M2 macrophage markers and related inflammatory factors after Chishao - Fuzi herbal pair intervention, both in vivo and in vitro.

RESULTS

Patients with HBV-ACLF exhibited an imbalance in M1/M2 macrophage polarization, showing a tendency to activate M1 macrophages with high expression of CD86 and iNOS. This imbalance led to an increase in relevant pro-inflammatory factors (IL-1β, IL-6, TNF-α) and a decrease in anti-inflammatory factors (IL-10, TGF-β, VEGF), exacerbating the uncontrolled immune-inflammatory response. Chishao - Fuzi herbal pair intervention improved liver function, coagulation function, and histopathological injury in ACLF rats. It also partially ameliorated endotoxemia and inflammatory injury in ACLF. The mechanism was to restore the immune-inflammatory imbalance and prevent the exacerbation of inflammatory response to liver failure by promoting macrophage polarization toward M2 anti-inflammatory direction, inhibiting M1 macrophage activation, and increasing the levels of anti-inflammatory factors and decreasing pro-inflammatory factors.

CONCLUSION

Chishao - Fuzi herbal pair can reduce the systemic inflammatory burden of liver failure by modulating macrophage polarization and restoring ACLF immune-inflammatory imbalance. This study provides new perspectives and strategies for studying HBV-ACLF immune reconstitution and inflammatory response control.

A clinical study of non-bioartificial liver DPMAES support system in hepatitis B-related acute-on-chronic liver failure

This study aims to observe the clinical efficacy of the dual plasma molecular adsorption exchange system (DPMAES) in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF), with a focus on its regulatory effect on cytokine storm. A total of 60 HBV-ACLF patients were enrolled in this study. The observation group, comprising 30 patients, received DPMAES treatment, while the control group underwent PE treatment. We compared the efficacy changes between the two groups post-treatment. A total of 55 HBV-ACLF patients who completed the study were analyzed, Patients treated with DPMAES showed significant improvements in clinical outcomes. After DPMAES treatment, HBV-ACLF patients exhibited notably 90 day survival rate increased by 18% compared to those in the PE group. Moreover, total bilirubin levels decreased markedly, albumin and platelet levels increased compared to the PE group. After DPMAES treatment, the patient showed a significant decrease in inflammatory cytokine IL-6 (t = 5.046, P < 0.001) and a significant decrease in procalcitonin (t = 4.66, P < 0.001). DPMAES was more effective than PE in rapidly reducing TBiL, improving coagulation function and mitigating cytokine storm. It maintained platelet stability more effectively while minimizing albumin consumption to a greater extent, significantly improved 90-day survival.Trial registration: Chinese Clinical Trial Registry, ChiCTR2300076117.

Comparative analysis of monocyte-derived dendritic cell phenotype and T cell stimulatory function in patients with acute-on-chronic liver failure with different clinical parameters

BACKGROUND

Acute-on-Chronic Liver Failure (ACLF) patients experience systemic inflammation as well as immune dysfunction and exhaustion. The phenotype and functionality of monocyte-derived dendritic cells in ACLF patients with different clinical parameters have not been elucidated.

METHODS

This study included 37 cases of ACLF, 20 cases of Chronic Hepatitis B (CHB) patients, and 12 healthy controls. Demographic and laboratory parameters were collected from the enrolled patients. Peripheral blood samples were obtained from the participants. Monocyte-derived dendritic cells were induced and cultured, followed by co-culturing with T cells from the patients. Cell surface markers and intracellular markers were analyzed using flow cytometry. The relationship between these markers and clinical parameters was compared.

RESULTS

Our study found that ACLF patients had lower expression levels of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells compared to both CHB patients and healthy controls. IL-4, GM-CSF, and alcohol were found to promote the expression of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells. In ACLF patients, higher levels of procalcitonin (PCT), lower levels of albumin, decreased prothrombin activity and deceased patients were associated with lower expression of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells. Peripheral blood mononuclear cells (PBMCs), after removing adherent cells, were co-cultured with monocyte-derived DC. Our study revealed that patients with infection and low albumin levels exhibited a decreased proportion of T cell subsets within PBMCs. Additionally, these patients' T cells showed lower levels of Ki-67 and interferon-gamma (IFN-γ) production.

CONCLUSION

ACLF patients exhibit varying clinical states, with differences in the phenotype and the ability of monocyte-derived dendritic cells to stimulate T cells. Alcohol can stimulate the maturation of monocyte-derived dendritic cells.

Progesterone modulates extracellular heat-shock proteins and interlukin-1β in human choriodecidual after Escherichia coli infection

INTRODUCTION

Chorioamnionitis is an adverse condition in human pregnancy caused by many bacterial pathogens including Escherichia coli (E. coli); which has been associated with higher risk of preterm birth. We recently reported that human maternal decidua (MDec) tissue responds to E. coli infection by secreting extracellular heat-shock proteins (eHsp)-60, -70 and interlukin-1β (IL-1β). Previous studies have shown that progesterone (P4) regulates the immune response, but it is unknown whether P4 inhibits the secretion of eHsp. The aim of this investigation was to determine the role of P4 on the secretion of eHsp-27, -60, -70 and IL-1β in MDec after 3, 6, and 24 h of E. coli infection.

METHODS

Nine human feto-maternal interface (HFMi) tissues were included and mounted in the Transwell culture system. Only the maternal decidua (MDec) was stimulated for 3, 6 and 24 h with E. coli alone or in combination with progesterone and RU486. After each treatment, the HFMi tissue was recovered to determine histological changes and the culture medium recovered to evaluate the levels of eHsp-27, -60, -70 and IL-1β by ELISA and mRNA expression by RT-PCR.

RESULTS

No structural changes were observed in the HFMi tissue treated with P4 and RU486. However, stimulation with E. coli produces diffuse inflammation and ischemic necrosis. E. coli induced infection decreases, in time- and dose-dependent manner, eHsp-27 and increases eHsp-60, eHsp-70 and IL-1β levels. In contrast, incubation of HFMi tissue with E. coli + P4 reversed eHsp and IL-1β secretion levels relative to E. coli stimulation group but not relative to the control group. The same profile was observed on the expression of eHsp-27 and eHsp-60.

DISCUSSION

we found that progesterone modulates the anti-inflammatory (eHsp-27) and pro-inflammatory (eHsp-60 and eHsp-70) levels of eHsp induced by E. coli infection in human choriodecidual tissue. eHsp-60 and eHsp-70 levels were not completely reversed; maintaining the secretion of IL-1β, which has been associated with adverse events during pregnancy.

Sterile inflammation in liver transplantation

Sterile inflammation is the immune response to damage-associated molecular patterns (DAMPs) released during cell death in the absence of foreign pathogens. In the setting of solid organ transplantation, ischemia-reperfusion injury results in mitochondria-mediated production of reactive oxygen and nitrogen species that are a major cause of uncontrolled cell death and release of various DAMPs from the graft tissue. When properly regulated, the immune response initiated by DAMP-sensing serves as means of damage control and is necessary for initiation of recovery pathways and re-establishment of homeostasis. In contrast, a dysregulated or overt sterile inflammatory response can inadvertently lead to further injury through recruitment of immune cells, innate immune cell activation, and sensitization of the adaptive immune system. In liver transplantation, sterile inflammation may manifest as early graft dysfunction, acute graft failure, or increased risk of immunosuppression-resistant rejection. Understanding the mechanisms of the development of sterile inflammation in the setting of liver transplantation is crucial for finding reliable biomarkers that predict graft function, and for development of therapeutic approaches to improve long-term transplant outcomes. Here, we discuss the recent advances that have been made to elucidate the early signs of sterile inflammation and extent of damage from it. We also discuss new therapeutics that may be effective in quelling the detrimental effects of sterile inflammation.

Acute kidney injury in patients with acute-on-chronic liver failure: clinical significance and management

Acute-on-chronic-liver failure (ACLF) refers to a phenomenon in which patients with chronic liver disease develop multiple organ failure due to acute exacerbation of underlying liver disease. More than 10 definitions of ACLF are extant around the world, and there is lack of consensus on whether extrahepatic organ failure is a main component or a consequence of ACLF. Asian and European consortiums have their own definitions of ACLF. The Asian Pacific Association for the Study of the Liver ACLF Research Consortium does not consider kidney failure as a diagnostic criterion for ACLF. Meanwhile, the European Association for the Study of the Liver Chronic Liver Failure and the North American Consortium for the Study of End-stage Liver Disease do consider kidney failure as an important factor in diagnosing and assessing the severity of ACLF. When kidney failure occurs in ACLF patients, treatment varies depending on the presence and stage of acute kidney injury (AKI). In general, the diagnosis of AKI in cirrhotic patients is based on the International Club of Ascites criteria: an increase of 0.3 mg/dL or more within 48 hours or a serum creatinine increase of 50% or more within one week. This study underscores the importance of kidney failure or AKI in patients with ACLF by reviewing its pathophysiology, prevention methods, and treatment approaches.

DLL4-Notch signalling in acute-on-chronic liver failure: State of the art and perspectives

Acute-on-chronic liver failure (ACLF) is a syndrome characterized by acute decompensation of chronic liver disease associated with multiple-organ failures and high short-term mortality. Acute insults to patients with chronic liver disease can lead to ACLF, among which, hepatitis B virus-related ACLF is the most common type of liver failure in the Asia-Pacific region. Currently, immune-metabolism disorders and systemic inflammation are proposed to be the main mechanisms of ACLF. The resulting cholestasis and intrahepatic microcirculatory dysfunction accelerate the development of ACLF. Treatments targeting immune regulation, metabolic balance, microcirculation maintenance and bile duct repair can alleviate inflammation and restore the tissue structure. An increasing number of studies have demonstrated that delta-like ligand 4 (DLL4), one of the Notch signalling ligands, plays a vital role in immune regulation, metabolism, angiogenesis, and biliary regeneration, which participate in liver pathological and physiological processes. The detailed mechanism of the DLL4-Notch signalling pathway in ACLF has rarely been investigated. Here, we review the evidence showing that DLL4-Notch signalling is involved in ACLF and analyse the potential role of DLL4 in the treatment of ACLF.

Targeted modulation of gut microbiota by traditional Chinese medicine and natural products for liver disease therapy

The gut microbiota not only constitutes intestinal microenvironment homeostasis and human health but also exerts indispensable roles in the occurrence and progression of multiple liver diseases, including alcohol-related liver disease, nonalcoholic fatty liver disease, autoimmune liver disease and liver cancer. Given the therapeutic status of these diseases, their prevention and early therapy are crucial, and the detailed mechanism of gut microbiota in liver disease urgently needs to be explored. Meanwhile, multiple studies have shown that various traditional Chinese medicines, such as Si Miao Formula, Jiangzhi Granules, Liushen Capsules, Chaihu-Shugan Power, Cassiae Semen and Gynostemma, as well as some natural products, including Costunolide, Coprinus comatus polysaccharide, Antarctic krill oil, Oridonin and Berberine, can repair liver injury, improve fatty liver, regulate liver immunity, and even inhibit liver cancer through multiple targets, links, and pathways. Intriguingly, the aforementioned effects demonstrated by these traditional Chinese medicines and natural products have been shown to be closely related to the gut microbiota, directly driving the strategy of traditional Chinese medicines and natural products to regulate the gut microbiota as one of the breakthroughs in the treatment of liver diseases. Based on this, this review comprehensively summarizes and discusses the characteristics, functions and potential mechanisms of these medicines targeting gut microbiota during liver disease treatment. Research on the potential effects on gut microbiota and the regulatory mechanisms of traditional Chinese medicine and natural products provides novel insights and significant references for developing liver disease treatment strategies. In parallel, such explorations will enhance the comprehension of traditional Chinese medicine and natural products modulating gut microbiota during disease treatment, thus facilitating their clinical investigation and application.