Mitochondrial dysfunction governs immunometabolism in leukocytes of patients with acute-on-chronic liver failure

Serum FGF21 as a predictor of response to atezolizumab and bevacizumab in HCC

Background & Aims

Fibroblast growth factor 21 (FGF21) is a crucial regulator of cell metabolism. Tumour-secreted FGF21 has shown immune-checkpoint factor functions, and high FGF21 levels are associated with a poor prognosis for patients. However, its prognostic value and impact on treatment response in patients with hepatocellular carcinoma (HCC) treated with immune-checkpoint inhibitors (ICIs) remain unclear. Thus, this study investigated the potential of high FGF21 levels as a prognostic marker and whether traditional ICI-based therapy can improve the prognosis of patients with high FGF21 levels.

Methods

In this retrospective multicentre study, patients with unresectable HCC who received atezolizumab/bevacizumab in the NORTE study group (n = 117) were classified into high (≥915 pg/ml; n = 29) and non-high (n = 88) FGF21 groups. For validation, we investigated patients treated with atezolizumab/bevacizumab in an independent cohort (n = 285). Overall survival, progression-free survival, and treatment response were compared between patients with and without high baseline FGF21 levels.

Results

The median overall survival (p <0.001) and progression-free survival (p = 0.045) were significantly shorter in the high FGF21 group than in the non-high FGF21 group. Independent cohort analysis validated these results. In the overall cohort, the median progression-free survival (5.75 vs. 8.84 months; p = 0.027) and median overall survival (14.13 vs. 22.08 months; p <0.001) were significantly shorter in the high FGF21 group than in the non-high FGF21 group. The durable response (≥6 months) + complete response rate was significantly decreased in the high FGF21 group (p = 0.045). No patient with a high FGF21 level achieved a complete response, whereas this was achieved in 4.1% (13/319) of patients with non-high FGF21 levels. Multivariate Cox regression analysis identified high baseline serum FGF21 as an independent poor prognostic factor for overall survival (hazard ratio 2.20, p <0.001).

Conclusions

Serum FGF21 may be a robust, non-invasive prognostic and treatment response marker for unresectable HCC treated with atezolizumab/bevacizumab.

Impact and implications

FGF21 has been reported to act as a secreted immune-checkpoint factor, and elevated levels of FGF21 are associated with a poor prognosis in patients with HCC. It is not fully understood whether ICIs can overcome the impact of high FGF21 levels on the shortened prognosis of patients with HCC. In this multicentre retrospective study, patients with HCC and high baseline levels of serum FGF21 who received atezolizumab/bevacizumab treatment exhibited a significantly shorter overall survival and shorter progression-free survival. These findings suggest serum FGF21 as a robust prognostic marker and an indicator of treatment response in unresectable HCC treated with ICI-based therapy. These findings could be crucial for the implementation of personalised treatment strategies for unresectable HCC. However, identifying optimal therapeutic options for patients with unresectable HCC and high serum FGF21 levels remains an urgent and critical clinical issue.

NK-cell-elicited gasdermin-D-dependent hepatocyte pyroptosis induces neutrophil extracellular traps that facilitate HBV-related acute-on-chronic liver failure

BACKGROUND AND AIMS

HBV infection is a major etiology of acute-on-chronic liver failure (ACLF). At present, the pattern and regulation of hepatocyte death during HBV-ACLF progression are still undefined. Evaluating the mode of cell death and its inducers will provide new insights for developing therapeutic strategies targeting cell death. In this study, we aimed to elucidate whether and how immune landscapes trigger hepatocyte death and lead to the progression of HBV-related ACLF.

APPROACH AND RESULTS

We identified that pyroptosis represented the main cell death pattern in the liver of patients with HBV-related ACLF. Deficiency of MHC-I in HBV-reactivated hepatocytes activated cytotoxic NK cells, which in turn operated in a perforin/granzyme-dependent manner to trigger GSDMD/caspase-8-dependent pyroptosis of hepatocytes. Neutrophils selectively accumulated in the pyroptotic liver, and HMGB1 derived from the pyroptotic liver constituted an important factor triggering the generation of pathogenic extracellular traps in neutrophils (NETs). Clinically, elevated plasma levels of myeloperoxidase-DNA complexes were a promising prognostic biomarker for HBV-related ACLF. More importantly, targeting GSDMD pyroptosis-HMGB1 release in the liver abrogates NETs that intercept the development of HBV-related ACLF.

CONCLUSIONS

Studying the mechanisms that selectively modulate GSDMD-dependent pyroptosis, as well as its immune landscapes, will provide a novel strategy for restoring the liver function of patients with HBV-related ACLF.

Mechanisms of immunity in acutely decompensated cirrhosis and acute-on-chronic liver failure

The identification of systemic inflammation (SI) as a central player in the orchestration of acute-on-chronic liver failure (ACLF) has opened new avenues for the understanding of the pathophysiological mechanisms underlying this disease condition. ACLF, which develops in patients with acute decompensation of cirrhosis, is characterized by single or multiple organ failure and high risk of short-term (28-day) mortality. Its poor outcome is closely associated with the severity of the systemic inflammatory response. In this review, we describe the key features of SI in patients with acutely decompensated cirrhosis and ACLF, including the presence of a high blood white cell count and increased levels of inflammatory mediators in systemic circulation. We also discuss the main triggers (i.e. pathogen- and damage-associated molecular patterns), the cell effectors (i.e. neutrophils, monocytes and lymphocytes), the humoral mediators (acute phase proteins, cytokines, chemokines, growth factors and bioactive lipid mediators) and the factors that influence the systemic inflammatory response that drive organ failure and mortality in ACLF. The role of immunological exhaustion and/or immunoparalysis in the context of exacerbated inflammatory responses that predispose ACLF patients to secondary infections and re-escalation of end-organ dysfunction and mortality are also reviewed. Finally, several new potential immunogenic therapeutic targets are debated.

Omics in acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is a critical syndrome that develops in patients with chronic liver disease and is characterized by acute decompensation, single- or multiple-organ failure and high short-term mortality. Over the past few decades, ACLF has been progressively recognized as an independent clinical entity, and several criteria and prognostic scores have been proposed and validated by different scientific societies. However, controversies still exist in some aspects across regions, which mainly involve whether the definition of underlying liver diseases should include cirrhosis and non-cirrhosis. The pathophysiology of ACLF is complicated and remains unclear, although accumulating evidence based on different aetiologies of ACLF shows that it is closely associated with intense systemic inflammation and immune-metabolism disorder, which result in mitochondrial dysfunction and microenvironment imbalance, leading to disease development and organ failure. In-depth insight into the biological pathways involved in the mechanisms of ACLF and potential mechanistic targets that improve patient survival still needs to be investigated. Omics-based analytical techniques, including genomics, transcriptomics, proteomics, metabolomics and microbiomes, have developed rapidly and can offer novel insights into the essential pathophysiologic process of ACLF. In this paper, we briefly reviewed and summarized the current knowledge and recent advances in the definitions, criteria and prognostic assessments of ACLF; we also described the omics techniques and how omics-based analyses have been applied to investigate and characterize the biological mechanisms of ACLF and identify potential predictive biomarkers and therapeutic targets for ACLF. We also outline the challenges, future directions and limitations presented by omics-based analyses in clinical ACLF research.

Proteomics-guided Biomarker Discovery, Validation, and Pathway Perturbation in Infection-related Acute Decompensation of Cirrhosis

BACKGROUND & AIMS

Inappropriate treatment of infections fuels drug resistance, organ failures, and costs in cirrhosis. We explored proteomics to improve infection diagnosis and management in acutely decompensated (AD) cirrhosis.

METHODS

We enrolled 391 patients with AD cirrhosis (92% males, median-age: 41 years), 84 in the discovery cohort (54 infected, 30 non-infected), 147 in the validation cohort I (106 infected, 41 non-infected), and 160 in the validation cohort II (108 infected, 52 non-infected). High-throughput proteomics identified biomarkers in the discovery cohort, validated through enzyme-linked immunoassay in subsequent cohorts. A model for infection was evaluated through discrimination, calibration, and decision curves and was externally validated.

RESULTS

Infected patients exhibited higher leucocyte counts, procalcitonin, organ failures, Model for End-stage Liver Disease scores, and 30-day mortality (P < .001 each). Proteomics identified 516 proteins, 27 upregulated and 38 downregulated, in infections. LGALS3BP, PLTP, CFP, and GPX3 were independently linked to infections (adjusting for severity and systemic inflammatory response syndrome), with composite area under the receiver operating characteristic curve (AUC) of 0.854 (95% confidence interval [CI], 0.787-0.922) in validation cohort I. A PACIFY model (LGALS3BP + procalcitonin + CLIF-COF + lactate) predicted infections with AUC of 0.965 (95% CI, 0.933-0.997) and 0.906 (95% CI, 0.860-0.952) in validation cohorts I and II, outperforming procalcitonin, systemic inflammatory response syndrome, white blood cell, neutrophil-to-lymphocyte ratio, neutrophil %, and composite models (P < .001). The model demonstrated fair calibration, with decision curves indicating a net benefit of the model in treating infections and reducing unnecessary antimicrobial use. Consistent findings were observed on external validation (AUC, 0.949; 95% CI, 0.916-0.982), re-enforcing the accuracy and clinical utility of the model. A deployable app was developed for infection risk estimation, enhancing practical applicability. Impaired phagocytosis, complement functions, hypocoagulation, hypofibrinolysis, dysregulated carbohydrate metabolism, autophagy, heightened cell death, and proteolysis were key perturbed pathways in infections.

CONCLUSION

The study identifies novel protein signatures and pathways linked with infections in AD cirrhosis. A biomarker-guided treatment of infections can limit unnecessary antimicrobial use and the burden of drug resistance in cirrhosis.

Distinct immunometabolic signatures in circulating immune cells define disease outcome in acute-on-chronic liver failure

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a complication of cirrhosis characterized by multiple organ failure and high short-term mortality. The pathophysiology of ACLF involves elevated systemic inflammation leading to organ failure, along with immune dysfunction that heightens susceptibility to bacterial infections. However, it is unclear how these aspects are associated with recovery and nonrecovery in ACLF.

APPROACH AND RESULTS

Here, we mapped the single-cell transcriptome of circulating immune cells from patients with ACLF and acute decompensated (AD) cirrhosis and healthy individuals. We further interrogate how these findings, as well as immunometabolic and functional profiles, associate with ACLF-recovery (ACLF-R) or nonrecovery (ACLF-NR). Our analysis unveiled 2 distinct states of classical monocytes (cMons). Hereto, ACLF-R cMons were characterized by transcripts associated with immune and stress tolerance, including anti-inflammatory genes such as RETN and LGALS1 . Additional metabolomic and functional validation experiments implicated an elevated oxidative phosphorylation metabolic program as well as an impaired ACLF-R cMon functionality. Interestingly, we observed a common stress-induced tolerant state, oxidative phosphorylation program, and blunted activation among lymphoid populations in patients with ACLF-R. Conversely, ACLF-NR cMon featured elevated expression of inflammatory and stress response genes such as VIM , LGALS2 , and TREM1 , along with blunted metabolic activity and increased functionality.

CONCLUSIONS

This study identifies distinct immunometabolic cellular states that contribute to disease outcomes in patients with ACLF. Our findings provide valuable insights into the pathogenesis of ACLF, shedding light on factors driving either recovery or nonrecovery phenotypes, which may be harnessed as potential therapeutic targets in the future.

Mitochondrial dysfunction and lipid alterations in primary sclerosing cholangitis

OBJECTIVES

Indications of mitochondrial dysfunction are commonly seen in liver diseases, but data are scarce in primary sclerosing cholangitis (PSC). Analyzing circulating and liver-resident molecules indirectly reflecting mitochondrial dysfunction, we aimed to comprehensively characterize this deficit in PSC, and whether this was PSC specific or associated with cholestasis.

MATERIALS AND METHODS

We retrospectively included plasma from 191 non-transplant patients with large-duct PSC and 100 healthy controls and explanted liver tissue extracts from 24 PSC patients and 18 non-cholestatic liver disease controls. Using mass spectroscopy, we profiled lipids and fatty acids, carnitine, acylcarnitines, and metabolites in the tryptophan-kynurenine-nicotinamide pathway.

RESULTS

Hierarchal clustering of fatty acid levels identified patients with PSC and healthy controls as separate clusters. Compared to healthy controls, PSC patients had increased levels of monounsaturated fatty acids (MUFA) and palmitate (C16:0) in plasma, but reduced levels of long-chain saturated fatty acids (SFAs). These findings were more pronounced in PSC patients with cholestasis. Several n-3 polyunsaturated fatty acids were elevated in PSC but not associated with cholestasis. Acylcarnitine ratios C2/C5 and C2/C3 were elevated while C2/C16 was reduced in PSC, indicating impaired mitochondrial fatty acid oxidation of medium-long chained fatty acids. Levels of intermediates in the tryptophan-kynurenine pathway indicated impaired NAD biosynthesis, suggesting impaired energy supply to mitochondria in PSC.

CONCLUSIONS

We found that mitochondrial dysfunction was prominent in PSC and associated with increasing cholestasis. Whether this is merely a marker of liver disease and severity, or an underlying driver and potential therapeutic target in PSC remains to be explored.

Grifola frondosa Polysaccharide Ameliorates Inflammation by Regulating Macrophage Polarization of Liver in Type 2 Diabetes Mellitus Rats

SCOPE

Grifola frondosa polysaccharide (GFP) has a positive effect in regulating type 2 diabetes mellitus (T2DM), but the understanding of its regulatory mechanism is still limited. Accumulating evidence suggests that hepatic inflammation is crucial in the onset and progression of insulin resistance (IR) and T2DM. However, the question of whether GFP can modulate T2DM via regulating hepatic inflammation and the underlying mechanism has not yet been reported.

METHODS AND RESULTS

High-fat diet (HFD) fed combined with streptozocin (STZ) injections rat model and Lipopolysaccharides (LPS)-treated bone marrow-derived macrophages (BMDM) model are used. The results showed that GFP intervention reduces weight loss and hyperglycemia symptoms, besides lowers FINS, HOMA-IR, IPGTT-AUC, and IPITT-AUC in T2DM rats. Meanwhile, GFP intervention reduces the secretion level of inflammatory factors and increases the secretion level of anti-inflammatory factors in the liver tissue of T2DM rats. Furthermore, GFP reduces macrophage infiltration in liver tissue, inhibits macrophage M1-type polarization, and promotes M2-type polarization.

CONCLUSIONS

These results suggest that GFP intervention could attenuate the hepatic inflammatory and insulin resistance in T2DM rats by inhibiting hepatic macrophage infiltration and modulating M1/M2 polarization. The findings provide new evidence for GFP in the early prevention and treatment of T2DM.

Palmitoylcarnitine impairs immunity in decompensated cirrhosis

Background & Aims

In patients with cirrhosis, acute decompensation (AD) correlates with a hyperinflammatory state driven by mitochondrial dysfunction, which is a significant factor in the progression toward acute-on-chronic liver failure (ACLF). Elevated circulating levels of acylcarnitine, indicative of mitochondrial dysfunction, are predictors of mortality in ACLF patients. Our hypothesis posits that acylcarnitines not only act as biomarkers, but also actively exert detrimental effects on circulating immune cells.

Methods

Plasma acylcarnitine levels were measured in 20 patients with AD cirrhosis and 10 healthy individuals. The effects of selected medium- and long-chain acylcarnitines on mitochondrial function were investigated in peripheral leucocytes from healthy donors by determining mitochondrial membrane potential (Δψm) and mitochondrial respiration using the JC-1 dye and Agilent Seahorse XF technology. Changes regarding mitochondrial ultrastructure and redox systems were assessed by transmission electron microscopy and gene and protein expression analysis.

Results

Plasma levels of several acylcarnitine species were significantly elevated in patients with AD cirrhosis compared with healthy individuals, alongside increased levels of inflammatory mediators (cytokines and chemokines). Notably, the long-chain acylcarnitine palmitoylcarnitine (C16:0-carnitine, 1.51-fold higher, p = 0.0059) impaired Δψm and reduced the spare respiratory capacity of peripheral mononuclear leucocytes. Additionally, C16:0-carnitine induced mitochondrial oxidative stress, suppressed the expression of the antioxidant gene HMOX1, and increased CXCL8 expression and IL-8 release. Etomoxir, which blocks acylcarnitine entry into the mitochondria, reversed the suppression of HMOX1. Similarly, trimetazidine, a fatty acid beta-oxidation inhibitor, prevented C16:0-carnitine-induced CXCL8 expression. Importantly, oxidative stress and Δψm impairment caused by C16:0-carnitine were less severe in the presence of albumin, a standard therapy for AD cirrhosis.

Conclusions

Our findings suggest that long-chain acylcarnitines induce mitochondrial injury in immune cells, thereby contributing to the development of immune dysfunction associated with cirrhosis.

Impact and implications

Patients with acute decompensation of cirrhosis and acute-on-chronic liver failure (ACLF) display a systemic hyperinflammatory state and leukocyte mitochondrial dysfunction. We discovered that apart from being increased in the circulation of these patients, the long-chain palmitoylcarnitine is able to elicit cytokine secretion paired with mitochondrial dysfunction in leukocytes from healthy donors. In particular, we show that inhibiting the metabolism of palmitoylcarnitine could reverse these detrimental effects. Our findings underline the importance of immunometabolism as a treatment target in patients with acute decompensation of cirrhosis and 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.

Targeting TGR5 to mitigate liver fibrosis: Inhibition of hepatic stellate cell activation through modulation of mitochondrial fission

Chronic hepatitis B virus (HBV) infection continues to be a prominent cause of liver fibrosis and end-stage liver disease in China, necessitating the development of effective therapeutic strategies. This study investigated the potential of targeting TGR5 to alleviate liver fibrosis by impeding the activation of hepatic stellate cells (HSCs), which play a pivotal role in fibrotic progression. Using the human hepatic stellate cell line LX-2 overexpressing hepatitis B virus X protein (HBX), this study revealed that TGR5 activation through INT-777 inhibits HBX-induced LX-2 cell activation, thereby ameliorating liver fibrosis, which is associated with the attenuation of mitochondrial fission and introduces a novel regulatory pathway in liver fibrosis. Additional experiments with mitochondrial fission inducers and inhibitors confirm the crucial role of mitochondrial dynamics in TGR5-mediated effects. In vivo studies using TGR5 knockout mice substantiate these findings, demonstrating exacerbated fibrosis in the absence of TGR5 and its alleviation with the mitochondrial fission inhibitor Mdivi-1. Overall, this study provides insights into TGR5-mediated regulation of liver fibrosis through the modulation of mitochondrial fission in HSCs, suggesting potential therapeutic strategies for liver fibrosis intervention.

FGF21 modulates immunometabolic homeostasis via the ALOX15/15-HETE axis in early liver graft injury

Fibroblast growth factor 21 (FGF21) is essential for modulating hepatic homeostasis, but the impact of FGF21 on liver graft injury remains uncertain. Here, we show that high FGF21 levels in liver graft and serum are associated with improved graft function and survival in liver transplantation (LT) recipients. FGF21 deficiency aggravates early graft injury and activates arachidonic acid metabolism and regional inflammation in male mouse models of hepatic ischemia/reperfusion (I/R) injury and orthotopic LT. Mechanistically, FGF21 deficiency results in abnormal activation of the arachidonate 15-lipoxygenase (ALOX15)/15-hydroxy eicosatetraenoic acid (15-HETE) pathway, which triggers a cascade of innate immunity-dominated pro-inflammatory responses in grafts. Notably, the modulating role of FGF21/ALOX15/15-HETE pathway is more significant in steatotic livers. In contrast, pharmacological administration of recombinant FGF21 effectively protects against hepatic I/R injury. Overall, our study reveals the regulatory mechanism of FGF21 and offers insights into its potential clinical application in early liver graft injury after LT.

The Impact of Liver Failure on the Immune System

Liver failure profoundly affects the immune system, leading to dysregulation of innate and adaptive immune response. This review explores the intricate relationship between liver function and immune homeostasis. The role of the liver as a central hub in immune response initiation is elucidated, emphasizing its involvement in hepatic inflammation induction and subsequent systemic inflammation. Cytokines, chemokines, growth factors, and lipid mediators orchestrate these immune processes, serving as both prognostic biomarkers and potential therapeutic targets in liver failure-associated immune dysregulation, which might result from acute-on-chronic liver failure (ACLF) and cirrhosis. Furthermore, the review delves into the mechanisms underlying immunosuppression in liver failure, encompassing alterations in innate immune cell functions such as neutrophils, macrophages, and natural killer cells (NK cells), as well as perturbations in adaptive immune responses mediated by B and T cells. Conclusion: Understanding the immunological consequences of liver failure is crucial for developing targeted therapeutic interventions and improving patient outcomes in liver disease management.

Disrupted mitochondrial transcription factor A expression promotes mitochondrial dysfunction and enhances ocular surface inflammation by activating the absent in melanoma 2 inflammasome

PURPOSE

Severe dry eye disease causes ocular surface damage, which is highly associated with mitochondrial dysfunction. Mitochondrial transcription factor A (TFAM) is essential for packaging mitochondrial DNA (mtDNA) and is crucial for maintaining mitochondrial function. Herein, we aimed to explore the effect of a decreased TFAM expression on ocular surface damage.

METHODS

Female C57BL/6 mice were induced ocular surface injury by topical administrating benzalkonium chloride (BAC). Immortalized human corneal epithelial cells (HCECs) were stimulated by tert-butyl hydroperoxide (t-BHP) to create oxidative stress damage. HCECs with TFAM knockdown were established. RNA sequencing was employed to analyze the whole-genome expression. Mitochondrial changes were measured by transmission electron microscopy, Seahorse metabolic flux analysis, mitochondrial membrane potential, and mtDNA copy number. TFAM expression and inflammatory cytokines were determined using RT-qPCR, immunohistochemistry, immunofluorescence, and immunoblotting.

RESULTS

In both the corneas of BAC-treated mice and t-BHP-induced HCECs, we observed impaired TFAM expression, accompanied by mitochondrial structure and function defects. TFAM downregulation in HCECs suppressed mitochondrial respiratory capacity, reduced mtDNA content, induced mtDNA leakage into the cytoplasm, and led to inflammation. RNA sequencing revealed the absent in melanoma 2 (AIM2) inflammasome was activated in the corneas of BAC-treated mice. The AIM2 inflammasome activation was confirmed in TFAM knockdown HCECs. TFAM knockdown in t-BHP-stimulated HCECs aggravated mitochondrial dysfunction and the AIM2 inflammasome activation, thereby further triggering the secretion of inflammatory factors such as interleukin (IL) -1β and IL-18.

CONCLUSIONS

TFAM reduction impaired mitochondrial function, activated AIM2 inflammasome and promoted ocular surface inflammation, revealing an underlying molecular mechanism for ocular surface disorders.

Acute kidney injury in patients with cirrhosis: Acute Disease Quality Initiative (ADQI) and International Club of Ascites (ICA) joint multidisciplinary consensus meeting

Patients with cirrhosis are prone to developing acute kidney injury (AKI), a complication associated with a markedly increased in-hospital morbidity and mortality, along with a risk of progression to chronic kidney disease. Whereas patients with cirrhosis are at increased risk of developing any phenotype of AKI, hepatorenal syndrome (HRS), a specific form of AKI (HRS-AKI) in patients with advanced cirrhosis and ascites, carries an especially high mortality risk. Early recognition of HRS-AKI is crucial since administration of splanchnic vasoconstrictors may reverse the AKI and serve as a bridge to liver transplantation, the only curative option. In 2023, a joint meeting of the International Club of Ascites (ICA) and the Acute Disease Quality Initiative (ADQI) was convened to develop new diagnostic criteria for HRS-AKI, to provide graded recommendations for the work-up, management and post-discharge follow-up of patients with cirrhosis and AKI, and to highlight priorities for further research.

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.

Outcome Predictors of Acute-on-Chronic Liver Failure: A Narrative Review

Complications of acute-on-chronic liver failure (ACLF) include increased short-term mortality. Extrahepatic organ failures result from chronic liver disease and acute hepatic injury. This combination characterizes end-stage liver disease. Its rapid progression makes it challenging for hepatologists and intensivists to treat. The varied definitions of this condition lead to varied clinical presentations. Hepatic or extrahepatic failures are more prevalent in chronic hepatitis B or cirrhosis patients who receive an additional injury. Numerous intensity parameters and prognosis ratings, including those for hepatitis B virus (HBV), have been developed and verified for various patients and causes of the disease. Liver regeneration, liver transplantation (LT), or antiviral therapy for HBV-related ACLF are the main treatment aims for various organ failures. LT is the best treatment for HBV-ACLF. In some HBV-related ACLF patients, nucleos(t)ide analogs and artificial liver assistance may enhance survival. Combining epidemiological and clinical studies, this review updates our understanding of HBV-ACLF's definition, diagnosis, epidemiology, etiology, therapy, and prognosis.

Development and validation of a prognostic model for 90-day survival in patients with alcohol-associated cirrhosis and acute decompensation

BACKGROUND/PURPOSE

Patients with alcohol-associated cirrhosis and acute decompensation are considered critically ill and have a higher risk of short-term mortality. This study aimed to establish a nomogram to evaluate their 90-day survival and identify factors that affect disease progression.

METHODS

We included patients from September 2008 to December 2016 (n = 387 in the derivation group) and from January 2017 to August 2020 (n = 157 in the validation group). LASSO regression and Cox multivariate risk regression were used to analyze the influencing factors of the 90-day mortality risk, and a nomogram was constructed. The performance of a model was analyzed based on the C-index, area under the receiver operating curve, calibration curve, and decision curve analysis.

RESULTS

Total bilirubin >10 upper limit of normal, high-density lipoprotein cholesterol, lymphocyte and monocyte ratios ≤2.33, white blood cells, and hemoglobin were identified as independent risk factors affecting the 90-day mortality risk of patients and the nomogram was developed. A nomogram demonstrated excellent model predictive accuracy in both the derivation and validation cohorts (C-index: 0.976 and 0.945), which was better than other commonly used liver scoring models (p < 0.05). The nomogram also performed good calibration ability and more clinical net benefit. According to the nomogram score, patients were divided into high- and low-risk groups. Mortality was significantly higher in the high-risk group than in the low-risk group (p < 0.0001).

CONCLUSION

The nomogram could accurately predict the 90-day mortality risk in patients with alcohol-associated cirrhosis and acute decompensation, helping to identify high-risk patients and personalize treatment at their first admission.

Monocyte bioenergetics: An immunometabolic perspective in metabolic dysfunction-associated steatohepatitis

Monocytes (Mos) are crucial in the evolution of metabolic dysfunction-associated steatotic liver disease (MASLD) to metabolic dysfunction-associated steatohepatitis (MASH), and immunometabolism studies have recently suggested targeting leukocyte bioenergetics in inflammatory diseases. Here, we reveal a peculiar bioenergetic phenotype in circulating Mos of patients with MASH, characterized by high levels of glycolysis and mitochondrial (mt) respiration. The enhancement of mt respiratory chain activity, especially complex II (succinate dehydrogenase [SDH]), is unbalanced toward the production of reactive oxygen species (ROS) and is sustained at the transcriptional level with the involvement of the AMPK-mTOR-PGC-1α axis. The modulation of mt activity with dimethyl malonate (DMM), an SDH inhibitor, restores the metabolic profile and almost abrogates cytokine production. Analysis of a public single-cell RNA sequencing (scRNA-seq) dataset confirms that in murine models of MASH, liver Mo-derived macrophages exhibit an upregulation of mt and glycolytic energy pathways. Accordingly, the DMM injection in MASH mice contrasts Mo infiltration and macrophagic enrichment, suggesting immunometabolism as a potential target in MASH.

The intersection of virus infection and liver disease: A comprehensive review of pathogenesis, diagnosis, and treatment

Liver disease represents a significant global burden, placing individuals at a heightened risk of developing cirrhosis and liver cancer. Viral infections act as a primary cause of liver diseases on a worldwide scale. Infections involving hepatitis viruses, notably hepatitis B, C, and E viruses, stand out as the most prevalent contributors to acute and chronic intrahepatic adverse outcome, although the hepatitis C virus (HCV) can be effectively cured with antiviral drugs, but no preventative vaccination developed. Hepatitis B virus (HBV) and HCV can lead to both acute and chronic liver diseases, including liver cirrhosis and hepatocellular carcinoma (HCC), which are principal causes of worldwide morbidity and mortality. Other viruses, such as Epstein-Barr virus (EBV) and cytomegalovirus (CMV), are capable of causing liver damage. Therefore, it is essential to recognize that virus infections and liver diseases are intricate and interconnected processes. A profound understanding of the underlying relationship between virus infections and liver diseases proves pivotal in the effective prevention, diagnosis, and treatment of these conditions. In this review, we delve into the mechanisms by which virus infections induce liver diseases, as well as explore the pathogenesis, diagnosis, and treatment of liver diseases. This article is categorized under: Infectious Diseases > Biomedical Engineering.

Immunopathogenesis of acute on chronic liver failure

Acute-on-chronic liver failure is a well-established description of a high-mortality syndrome of chronic liver disease (usually cirrhosis) with organ failure. While the exact definition is under refinement, the accepted understanding of this entity is in patients with chronic liver disease and various organs in failure and where systemic inflammation is a major component of the pathobiology. There are limited therapies for a disease with such a poor prognosis, and while improvements in the critical care management and for very few patients, liver transplantation, mean 50% can survive to hospital discharge, rapid application of new therapies is required. Here we explain the current understanding of the immunologic abnormalities seen in acute-on-chronic liver failure across the innate and adaptive immune systems, the role of the hepatic cell death and the gut-liver axis, and recommendations for future research and treatment paradigms.

Characteristics and risk factors for invasive fungal infection in hospitalized patients with acute-on-chronic hepatitis B liver failure: a retrospective cohort study from 2010 to 2023

BACKGROUND AND AIM

The global burden of invasive fungal infections (IFIs) is emerging in immunologic deficiency status from various disease. Patients with acute-on-chronic hepatitis B liver failure (ACHBLF) are prone to IFI and their conditions are commonly exacerbated by IFI. However, little is known about the characteristics and risk factors for IFI in hospitalized ACHBLF patients.

METHODS

A total of 243 hospitalized ACHBLF patients were retrospectively enrolled from January 2010 to July 2023. We performed restricted cubic spline analysis to determine the non-linear associations between independent variables and IFI. The risk factors for IFI were identified using logistic regression and the extreme gradient boosting (XGBoost) algorithm. The effect values of the risk factors were determined by the SHapley Additive exPlanations (SHAP) method.

RESULTS

There were 24 ACHBLF patients (9.84%) who developed IFI on average 17.5 (13.50, 23.00) days after admission. The serum creatinine level showed a non-linear association with the possibility of IFI. Multiple logistic regression revealed that length of hospitalization (OR = 1.05, 95% CI: 1.02-1.08, P = 0.002) and neutrophilic granulocyte percentage (OR = 1.04, 95% CI: 1.00-1.09, P = 0.042) were independent risk factors for IFI. The XGBoost algorithm showed that the use of antibiotics (SHAP value = 0.446), length of hospitalization (SHAP value = 0.406) and log (qHBV DNA) (SHAP value = 0.206) were the top three independent risk factors for IFI. Furthermore, interaction analysis revealed no multiplicative effects between the use of antibiotics and the use of glucocorticoids (P = 0.990).

CONCLUSION

IFI is a rare complication that leads to high mortality in hospitalized ACHBLF patients, and a high neutrophilic granulocyte percentage and length of hospitalization are independent risk factors for the occurrence of IFI.

Mitochondrial Dysfunction and Metabolic Reprogramming in Obesity and Asthma

Mitochondrial dysfunction and metabolic reprogramming have been extensively studied in many disorders ranging from cardiovascular to neurodegenerative disease. Obesity has previously been associated with mitochondrial fragmentation, dysregulated glycolysis, and oxidative phosphorylation, as well as increased reactive oxygen species production. Current treatments focus on reducing cellular stress to restore homeostasis through the use of antioxidants or alterations of mitochondrial dynamics. This review focuses on the role of mitochondrial dysfunction in obesity particularly for those suffering from asthma and examines mitochondrial transfer from mesenchymal stem cells to restore function as a potential therapy. Mitochondrial targeted therapy to restore healthy metabolism may provide a unique approach to alleviate dysregulation in individuals with this unique endotype.

Letter: Severe underweight and sarcopenia in decompensated cirrhosis are associated with high FGF21 levels

This article is linked to Alkhouri et al papers. To view these articles, visit https://doi.org/10.1111/apt.17709 and https://doi.org/10.1111/apt.17907

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.

Mitochondrial dysfunction affects hepatic immune and metabolic remodeling in patients with hepatitis B virus-related acute-on-chronic liver failure

BACKGROUND

Immune dysregulation and metabolic derangement have been recognized as key factors that contribute to the progression of hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF). However, the mechanisms underlying immune and metabolic derangement in patients with advanced HBV-ACLF are unclear.

AIM

To identify the bioenergetic alterations in the liver of patients with HBV-ACLF causing hepatic immune dysregulation and metabolic disorders.

METHODS

Liver samples were collected from 16 healthy donors (HDs) and 17 advanced HBV-ACLF patients who were eligible for liver transplantation. The mitochondrial ultrastructure, metabolic characteristics, and immune microenvironment of the liver were assessed. More focus was given to organic acid metabolism as well as the function and subpopulations of macrophages in patients with HBV-ACLF.

RESULTS

Compared with HDs, there was extensive hepatocyte necrosis, immune cell infiltration, and ductular reaction in patients with ACLF. In patients, the liver suffered severe hypoxia, as evidenced by increased expression of hypoxia-inducible factor-1α. Swollen mitochondria and cristae were observed in the liver of patients. The number, length, width, and area of mitochondria were adaptively increased in hepatocytes. Targeted metabolomics analysis revealed that mitochondrial oxidative phosphorylation decreased, while anaerobic glycolysis was enhanced in patients with HBV-ACLF. These findings suggested that, to a greater extent, hepa-tocytes used the extra-mitochondrial glycolytic pathway as an energy source. Patients with HBV-ACLF had elevated levels of chemokine C-C motif ligand 2 in the liver homogenate, which stimulates peripheral monocyte infiltration into the liver. Characterization and functional analysis of macrophage subsets revealed that patients with ACLF had a high abundance of CD68+ HLA-DR+ macrophages and elevated levels of both interleukin-1β and transforming growth factor-β1 in their livers. The abundance of CD206+ CD163+ macrophages and expression of interleukin-10 decreased. The correlation analysis revealed that hepatic organic acid metabolites were closely associated with macrophage-derived cytokines/chemokines.

CONCLUSION

The results indicated that bioenergetic alteration driven by hypoxia and mitochondrial dysfunction affects hepatic immune and metabolic remodeling, leading to advanced HBV-ACLF. These findings highlight a new therapeutic target for improving the treatment of HBV-ACLF.

LONP1 ameliorates liver injury and improves gluconeogenesis dysfunction in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a severe liver disease with complex pathogenesis. Clinical hypoglycemia is common in patients with ACLF and often predicts a worse prognosis. Accumulating evidence suggests that glucose metabolic disturbance, especially gluconeogenesis dysfunction, plays a critical role in the disease progression of ACLF. Lon protease-1 (LONP1) is a novel mediator of energy and glucose metabolism. However, whether gluconeogenesis is a potential mechanism through which LONP1 modulates ACLF remains unknown.

METHODS

In this study, we collected liver tissues from ACLF patients, established an ACLF mouse model with carbon tetrachloride (CCl 4 ), lipopolysaccharide (LPS), and D-galactose (D-gal), and constructed an in vitro hypoxia and hyperammonemia-triggered hepatocyte injury model. LONP1 overexpression and knockdown adenovirus were used to assess the protective effect of LONP1 on liver injury and gluconeogenesis regulation. Liver histopathology, biochemical index, mitochondrial morphology, cell viability and apoptosis, and the expression and activity of key gluconeogenic enzymes were detected to explore the underlying protective mechanisms of LONP1 in ACLF.

RESULTS

We found that LONP1 and the expressions of gluconeogenic enzymes were downregulated in clinical ACLF liver tissues. Furthermore, LONP1 overexpression remarkably attenuated liver injury, which was characterized by improved liver histopathological lesions and decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in ACLF mice. Moreover, mitochondrial morphology was improved upon overexpression of LONP1. Meanwhile, the expression and activity of the key gluconeogenic enzymes were restored by LONP1 overexpression. Similarly, the hepatoprotective effect was also observed in the hepatocyte injury model, as evidenced by improved cell viability, reduced cell apoptosis, and improved gluconeogenesis level and activity, while LONP1 knockdown worsened liver injury and gluconeogenesis disorders.

CONCLUSION

We demonstrated that gluconeogenesis dysfunction exists in ACLF, and LONP1 could ameliorate liver injury and improve gluconeogenic dysfunction, which would provide a promising therapeutic target for patients with ACLF.

Mitochondrial Stress and Mitokines: Therapeutic Perspectives for the Treatment of Metabolic Diseases

Mitochondrial stress and the dysregulated mitochondrial unfolded protein response (UPRmt) are linked to various diseases, including metabolic disorders, neurodegenerative diseases, and cancer. Mitokines, signaling molecules released by mitochondrial stress response and UPRmt, are crucial mediators of inter-organ communication and influence systemic metabolic and physiological processes. In this review, we provide a comprehensive overview of mitokines, including their regulation by exercise and lifestyle interventions and their implications for various diseases. The endocrine actions of mitokines related to mitochondrial stress and adaptations are highlighted, specifically the broad functions of fibroblast growth factor 21 and growth differentiation factor 15, as well as their specific actions in regulating inter-tissue communication and metabolic homeostasis. Finally, we discuss the potential of physiological and genetic interventions to reduce the hazards associated with dysregulated mitokine signaling and preserve an equilibrium in mitochondrial stress-induced responses. This review provides valuable insights into the mechanisms underlying mitochondrial regulation of health and disease by exploring mitokine interactions and their regulation, which will facilitate the development of targeted therapies and personalized interventions to improve health outcomes and quality of life.

Adaptive changes in tumor cells in response to reductive stress

Reductive stress is characterized by an excess of cellular electron donors and can be linked with various human pathologies including cancer. We developed melanoma cell lines resistant to reductive stress agents: rotenone (ROTR), n-acetyl-L-cysteine, (NACR), or dithiothreitol (DTTR). Resistant cells divided more rapidly and had intracellular homeostatic redox-couple ratios that were shifted towards the reduced state. Resistance caused alterations in general cell morphology, but only ROTR cells had significant changes in mitochondrial morphology with higher numbers that were more isolated, fragmented and swollen, with greater membrane depolarization and decreased numbers of networks. These changes were accompanied by lower basal oxygen consumption and maximal respiration rates. Whole cell flux analyses and mitochondrial function assays showed that NACR and DTTR preferentially utilized tricarboxylic acid (TCA) cycle intermediates, while ROTR used ketone body substrates such as D, L-β-hydroxybutyric acid. NACR and DTTR cells had constitutively decreased levels of reactive oxygen species (ROS), although this was accompanied by activation of nuclear factor erythroid 2-related factor 2 (Nrf2), with concomitant increased expression of the downstream gene products such as glutathione S-transferase P (GSTP). Further adaptations included enhanced expression of endoplasmic reticulum proteins controlling the unfolded protein response (UPR). Although expression patterns of these UPR proteins were distinct between the resistant cells, a trend implied that resistance to reductive stress is accompanied by a constitutively increased UPR phenotype in each line. Overall, tumor cells, although tolerant of oxidative stress, can adapt their energy and survival mechanisms in lethal reductive stress conditions.

Management of type 2 diabetes in patients with compensated liver cirrhosis: Short of evidence, plenty of potential

BACKGROUND AND AIMS

Treatment of type 2 diabetes (T2D) in patients with compensated cirrhosis is challenging due to hypoglycemic risk, altered pharmacokinetics, and the lack of robust evidence on the risk/benefit ratio of various drugs. Suboptimal glycemic control accelerates the progression of cirrhosis, while the frequent coexistence of nonalcoholic fatty liver disease (NAFLD) with T2D highlights the need for a multifactorial therapeutic approach.

METHODS

A literature search was performed in Medline, Google Scholar and Scopus databases till July 2023, using relevant keywords to extract studies regarding the management of T2D in patients with compensated cirrhosis.

RESULTS

Metformin, sodium-glucose co-transporter-2 inhibitors (SGLT2i), and glucagon-like peptide-1 receptor agonists (GLP-1 RA) are promising treatment options for patients with T2D and compensated liver cirrhosis, offering good glycemic control with minimal risk of hypoglycemia, while their pleiotropic actions confer benefits on NAFLD and body weight, and decrease cardiorenal risk. Sulfonylureas cause hypoglycemia, thus should be avoided, while in specific studies, dipeptidyl peptidase-4 inhibitors have been correlated with increased risk of decompensation and variceal bleeding. Despite the benefits of thiazolidinediones in nonalcoholic steatohepatitis, concerns about edema and weight gain limit their use in compensated cirrhosis. Insulin does not exert hepatotoxic effects and can be administered safely in combination with other drugs; however, the risk of hypoglycemia should be considered.

CONCLUSIONS

The introduction of new hepatoprotective diabetes drugs into clinical practice, including tirzepatide, SGLT2i, and GLP-1 RA, sets the stage for future trials to investigate the ideal therapeutic regimen for people with T2D and compensated cirrhosis.

Niujiao Dihuang Jiedu decoction promotes SLC7A11 m5C methylation modification against ferroptosis in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) constitutes a prevalent manifestation of liver failure within clinical settings. This condition manifests swiftly and is characterized by an exceedingly elevated fatality rate.

OBJECTIVE

While numerous investigations have delved into the role of RNA methylation in ferroptosis, the impact of such methylation on ACLF-associated ferroptosis remains notably underexplored. This study aimed to elucidate the molecular mechanism underlying the efficacy of Niujiao Dihuang Jiedu decoction (NDD) in mitigating ferroptosis in ACLF, with a specific focus on RNA 5-methylcytosine (m5C) methylation.

MATERIALS AND METHODS

An ACLF rat model was established alongside an erastin-induced ferroptosis model in LO2 cells. Both in vitro and in vivo experiments were conducted to substantiate NDD's influence on ferroptosis. The modifying influence of methylase NOL1/NOP2/sun domain (NSUN5) upon SLC7A11, a key ferroptosis-associated gene, was probed through dot blot, immunofluorescence co-localization, and RNA binding protein immunoprecipitation (RIP) experiments.

RESULTS

Serological and hepatic histopathological findings indicated NDD's discernible therapeutic impact on ACLF. Furthermore, ferroptosis phenotype experiments revealed NDD's proficiency in effectively impeding the occurrence and development of ferroptosis. Dot blot assays demonstrated a reduction in the overall RNA m5C levels during cellular ferroptosis. Furthermore, through immunofluorescence co-localization and RIP techniques, we found that the propensity of methylase NSUN5 to associate with SLC7A11 mRNA, thereby enhancing its protein translation and conferring resistance against ferroptosis.

CONCLUSION

RNA methylation is involved in the process of ACLF-associated ferroptosis, and NDD can inhibit ACLF-associated ferroptosis by fostering SLC7A11 m5C methylation.

Mitochondrial Dysfunction in Metabolic Dysfunction Fatty Liver Disease (MAFLD)

Nonalcoholic fatty liver disease (NAFLD) has become an increasingly common disease in Western countries and has become the major cause of liver cirrhosis or hepatocellular carcinoma (HCC) in addition to viral hepatitis in recent decades. Furthermore, studies have shown that NAFLD is inextricably linked to the development of extrahepatic diseases. However, there is currently no effective treatment to cure NAFLD. In addition, in 2020, NAFLD was renamed metabolic dysfunction fatty liver disease (MAFLD) to show that its pathogenesis is closely related to metabolic disorders. Recent studies have reported that the development of MAFLD is inextricably associated with mitochondrial dysfunction in hepatocytes and hepatic stellate cells (HSCs). Simultaneously, mitochondrial stress caused by structural and functional disorders stimulates the occurrence and accumulation of fat and lipo-toxicity in hepatocytes and HSCs. In addition, the interaction between mitochondrial dysfunction and the liver-gut axis has also become a new point during the development of MAFLD. In this review, we summarize the effects of several potential treatment strategies for MAFLD, including antioxidants, reagents, and intestinal microorganisms and metabolites.

Interleukin-8 predicts short-term mortality in acute-on-chronic liver failure patients with hepatitis B-related-related cirrhosis background

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a distinctive and severe syndrome, marked by an excessive systemic inflammatory response. In vivo, interleukin 8 (IL-8) is an essential pro-inflammatory cytokine. We aimed to investigate the value of serum IL-8 levels in predicting mortality in ACLF patients in the background of hepatitis B virus-related cirrhosis.

METHODS

In this study, we conducted a retrospective analysis of the clinical baseline characteristics of 276 patients with ACLF in the context of HBV-related cirrhosis. Logistic regression analysis was employed to identify independent risk factors for short-, intermediate-, and long-term mortality. Using these independent risk factors, we developed a nomogram model, which was subsequently validated. To assess the clinical usefulness of the nomogram model, we performed decision curve analysis (DCA).

RESULTS

Out of the 276 patients with ACLF, 98 (35.5%), 113 (40.9%), and 128 (46.4%) died within 28, 90, and 180 days, respectively. Serum IL-8 levels were only an independent predictor of 28-day mortality and could simply classify ACLF patients. Conversely, mean arterial pressure (MAP), HBV-DNA, and COSHACLF IIs were independent predictors of mortality across all three observation periods. We constructed a nomogram based on IL-8 that was able to visualise and predict 28-day mortality with a C-index of 0.901 (95% CI: 0.862-0.940). Our calibration curves, Predicted Probability of Death & Actual Survival Status plot, and Confusion Matrix demonstrated the nomogram model's strong predictive power. DCA indicated the nomogram's promising clinical utility in predicting 28-day mortality in ACLF patients.

CONCLUSION

Serum IL-8 levels predict short-term mortality in ACLF patients in the background of HBV-associated cirrhosis, and the developed Nomogram model has strong predictive power and good clinical utility.

Yi-Qi-Jian-Pi formula inhibits hepatocyte pyroptosis through the IDH2-driven tricarboxylic acid cycle to reduce liver injury in acute-on-chronic liver failure

ETHNOPHARMACOLOGICAL RELEVANCE

Yi-Qi-Jian-Pi formula (YQJPF) is a commonly used traditional Chinese medicine (TCM) compound used to treat acute-on-chronic liver failure (ACLF) in China, but its specific mechanism of action has not been fully clarified.

AIM OF THE STUDY

The aim of this study was to determine the effect of YQJPF on liver injury and hepatocyte pyroptosis in rats and further explore its molecular mechanism of action.

MATERIALS AND METHODS

This study established carbon tetrachloride (CCl4)-, lipopolysaccharide (LPS)- and D-galactose (D-Gal)-induced in vivo models of ACLF in rats and in vitro LPS-induced hepatocyte injury models. Animal experiments were divided into the following groups: control, ACLF model, groups with different doses of YQJPF (5.4, 10.8, and 21.6 g/kg), and western medicine (methylprednisolone). There were 7 rats in the control group and 11 in the other groups. Serological, immunohistochemical, and pathological analyses were used to observe the effect of YQJPF on the liver of ACLF rats. The protective effect of YQJPF on hepatocytes was further verified by RT-qPCR, western blotting, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and other methods.

RESULTS

YQJPF significantly improved liver injury in vivo and in vitro, which depended on the regulation of hepatocyte NLRP3/GSDMD-induced pyroptosis. In addition, we found that mitochondrial membrane potential and ATP production decreased after LPS treatment of hepatocytes, which suggested that YQJPF may improve mitochondrial energy metabolism disorders in hepatocytes. We administered a hepatocyte mitochondrial uncoupling agent, FCCP, to determine whether mitochondrial metabolic disorders affected cell pyroptosis. The results showed that the expression of IL-18, IL-1β, and NLRP3 proteins increased significantly, indicating that the effect of this drug on hepatocyte pyroptosis may be related to mitochondrial metabolism disorders. We found that YQJPF significantly restored the tricarboxylic acid (TCA) cycle rate-limiting enzyme activity and affected the content of TCA metabolites. Furthermore, we revealed that the IDH2 gene, which plays a unique role in ACLF, is a key factor in the regulation of the mitochondrial TCA cycle and can be upregulated under the action of YQJPF.

CONCLUSIONS

YQJPF can inhibit classical pyroptosis in hepatocytes by regulating TCA cycle metabolism, thus alleviating liver injury, and IDH2 may be a potential upstream regulatory target of YQJPF.

Liver metabolomics reveals potential mechanism of Jieduan-Niwan formula against acute-on-chronic liver failure (ACLF) by improving mitochondrial damage and TCA cycle

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a refractory disease with high mortality, which is characterized by a pathophysiological process of inflammation-related dysfunction of energy metabolism. Jieduan-Niwan formula (JDNWF) is a eutherapeutic Chinese medicine formula for ACLF. However, the intrinsic mechanism of its anti-ACLF effect still need to be studied systematically.

PURPOSE

This study aimed to investigate the mechanism of JDNWF against ACLF based on altered substance metabolic profile in ACLF the expression levels of related molecules.

MATERIALS AND METHODS

The chemical characteristics of JDNWF were characterized using ultra performance liquid chromatography (UPLC) coupled with triple quadrupole mass spectrometry. Wistar rats subjected to a long-term CCL4 stimulation followed by a combination of an acute attack with LPS/D-GalN were used to establish the ACLF model. Liver metabolites were analyzed by LC-MS/MS and multivariate analysis. Liver function, coagulation function, histopathology, mitochondrial metabolic enzyme activity and mitochondrial damage markers were evaluated. The protein expression of mitochondrial quality control (MQC) was investigated by western blot.

RESULTS

Liver function, coagulation function, inflammation, oxidative stress and mitochondrial enzyme activity were significantly improved by JDNWF. 108 metabolites are considered as biomarkers of JDNWF in treating ACLF, which were closely related to TCA cycle. It was further suggested that JDNWF alleviated mitochondrial damage and MQC may be potential mechanism of JDNWF improving mitochondrial function.

CONCLUSIONS

Metabolomics revealed that TCA cycle was impaired in ACLF rats, and JDNWF had a regulatory effect on it. The potential mechanism may be improving the mitochondrial function through MQC pathway, thus restoring energy metabolism.

Mesenchymal stem cell-regulated miRNA-mRNA landscape in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a major challenge in the field of hepatology. While mesenchymal stem cell (MSC) therapy can improve the prognosis of patients with ACLF, the molecular mechanisms through which MSCs attenuate ACLF remain poorly understood. We performed global miRNA and mRNA expression profiling via next-generation sequencing of liver tissues from MSC-treated ACLF mice to identify important signaling pathways and major factors implicated in ACLF alleviation by MSCs.

METHODS

Carbon tetrachloride-induced ACLF mice were treated with saline or mouse bone marrow-derived MSCs. Mouse livers were subjected to miRNA and mRNA sequencing. Related signal transduction pathways were obtained through Gene Set Enrichment Analysis. Functional enrichment, protein-protein interaction, and immune infiltration analyses were performed for the differentially expressed miRNA target genes (DETs). Hub miRNA and mRNA associated with liver injury were analyzed using LASSO regression. The expression levels of hub genes were subjected to Pearson's correlation analysis and verified using RT-qPCR. The biological functions of hub genes were verified in vitro.

RESULTS

The tricarboxylic acid cycle and peroxisome proliferator-activated receptor pathways were activated in the MSC-treated groups. The proportions of liver-infiltrating NK resting cells, M2 macrophages, follicular helper T cells, and other immune cells were altered after MSC treatment. The expression levels of six miRNAs and 10 transcripts correlated with the degree of liver injury. miR-27a-5p was downregulated in the mouse liver after MSC treatment, while its target gene E2f2 was upregulated. miR-27a-5p inhibited E2F2 expression, suppressed G1/S phase transition and proliferation of hepatocytes, in addition to promoting their apoptosis.

CONCLUSIONS

This is the first comprehensive analysis of miRNA and mRNA expression in the liver tissue of ACLF mice after MSC treatment. The results revealed global changes in hepatic pathways and immune subpopulations. The miR-27a-5p/E2F2 axis emerged as a central regulator of the MSC-induced attenuation of ACLF. The current findings improve our understanding of the molecular mechanisms through which MSCs alleviate ACLF.

Novel Morphological Profiling Assay Connects ex Vivo Endothelial Cell Responses to Disease Severity in Liver Cirrhosis

Background and Aims

Endothelial cell (EC) dysfunction in response to circulating plasma factors is a known causal factor in many systemic diseases. However, no appropriate assay is available to investigate this causality ex vivo. In liver cirrhosis, systemic inflammation is identified as central mechanism in progression from compensated to decompensated cirrhosis (DC), but the role of ECs therein is unknown. We aimed to develop a novel ex vivo assay for assessing EC responses to patient-derived plasma (PDP) and assess the potential of this assay in a cohort of liver cirrhosis patients.

Methods

Image-based morphological profiling was utilized to assess the impact of PDP on cultured ECs. Endothelial cell (EC) monolayers were exposed to 25% stabilized PDP (20 compensated cirrhoses, 20 DCs, and 20 healthy controls (HCs). Single-cell morphological profiles were extracted by automated image-analysis following staining of multiple cellular components and high-content imaging. Patient profiles were created by dimension reduction and cell-to-patient data aggregation, followed by multivariate-analysis to stratify patients and identify discriminating features.

Results

Patient-derived plasma (PDP) exposure induced profound changes in EC morphology, displaying clear differences between controls and DC patients. Compensated cirrhosis patients showed overlap with healthy controls and DC patients. Supervised analysis showed Child-Pugh (CP) class could be predicted from EC morphology. Most importantly, CP-C patients displayed distinct EC phenotypes, in which mitochondrial changes were most discriminative.

Conclusion

Morphological profiling presents a viable tool to assess the endothelium ex vivo. We demonstrated that the EC phenotype corresponds with disease severity in liver cirrhosis. Moreover, our results suggest the presence of mitochondrial dysfunction in ECs of CP-C patient.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

Biomolecular map of albumin identifies signatures of severity and early mortality in acute liver failure

BACKGROUND & AIMS

Acute liver failure (ALF) is associated with high mortality. Alterations in albumin structure and function have been shown to correlate with outcomes in cirrhosis. We undertook a biomolecular analysis of albumin to determine its correlation with hepatocellular injury and early mortality in ALF.

METHODS

Altogether, 225 participants (200 patients with ALF and 25 healthy controls [HC]) were enrolled. Albumin was purified from the baseline plasma of the training cohort (ALF, n = 40; survivors, n = 8; non-survivors, n = 32; and HC, n = 5); analysed for modifications, functionality, and bound multi-omics signatures; and validated in a test cohort (ALF, n = 160; survivors, n = 53; non-survivors, n = 107; and HC, n = 20).

RESULTS

In patients with ALF, albumin is more oxidised and glycosylated with a distinct multi-omics profile than that in HC, more so in non-survivors (p <0.05). In non-survivors, albumin was more often bound (p <0.05, false discovery rate <0.01) to proteins associated with inflammation, advanced glycation end product, metabolites linked to arginine, proline metabolism, bile acid, and mitochondrial breakdown products. Increased bacterial taxa (Listeria, Clostridium, etc.) correlated with lipids (triglycerides [4:0/12:0/12:0] and phosphatidylserine [39:0]) and metabolites (porphobilinogen and nicotinic acid) in non-survivors (r2 >0.7). Multi-omics signature-based probability of detection for non-survival was >90% and showed direct correlation with albumin functionality and clinical parameters (r2 >0.85). Probability-of-detection metabolites built on the top five metabolites, namely, nicotinic acid, l-acetyl carnitine, l-carnitine, pregnenolone sulfate, and N-(3-hydroxybutanoyl)-l-homoserine lactone, showed diagnostic accuracy of 98% (AUC 0.98, 95% CI 0.95-1.0) and distinguish patients with ALF predisposed to early mortality (log-rank <0.05). On validation using high-resolution mass spectrometry and five machine learning algorithms in test cohort 1 (plasma and paired one-drop blood), the metabolome panel showed >92% accuracy/sensitivity and specificity for prediction of mortality.

CONCLUSIONS

In ALF, albumin is hyperoxidised and substantially dysfunctional. Our study outlines distinct 'albuminome' signatures capable of distinguishing patients with ALF predisposed to early mortality or requiring emergency liver transplantation.

IMPACTS AND IMPLICATIONS

Here, we report that the biomolecular map of albumin is distinct and linked to severity and outcome in patients with acute liver failure (ALF). Detailed structural, functional, and albumin-omics analysis in patients with ALF led to the identification and classification of albumin-bound biomolecules, which could segregate patients with ALF predisposed to early mortality. More importantly, we found albumin-bound metabolites indicative of mitochondrial damage and hyperinflammation as a putative indicator of <30-day mortality in patients with ALF. This preclinical study validates the utility of albuminome analysis for understanding the pathophysiology and development of poor outcome indicators in patients with ALF.

Roles of systemic inflammatory and metabolic responses in the pathophysiology of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is the most severe form of acutely decompensated cirrhosis and is characterised by the presence of one or more organ failures, intense systemic inflammation, peripheral blood lymphopenia, and a high risk of death without liver transplantation within 28 days. Herein, we propose the hypothesis that intense systemic inflammation may lead to organ failures through five different non-mutually exclusive mechanisms. First, pathogen-associated molecular patterns and inflammatory mediators (i.e. cytokines and lipid mediators) stimulate the production of the vasorelaxant nitric oxide in the walls of splanchnic arterioles, leading to enhanced splanchnic and systemic vasodilation which, in turn, induces enhanced activity of endogenous vasoconstrictor systems causing renal vasoconstriction and acute kidney injury. Second, neutrophils that reach the systemic circulation are prone to adhere to the vascular endothelium. Cytokines and lipid mediators act on the endothelium in microvessels of vital organs, an effect that favours the migration of neutrophils (and probably other leukocytes) to surrounding tissues where neutrophils can cause tissue damage and thereby contribute to organ failure. Third, cytokines and lipid mediators promote the formation of microthrombi that impair microcirculation and tissue oxygenation. Fourth, acute inflammation stimulates intense peripheral catabolism of amino acids whose products may be metabotoxins that contribute to hepatic encephalopathy. Fifth, acute inflammatory responses, which include the production of a broad variety of biomolecules (proteins and lipids), and an increase in biomass (i.e., granulopoiesis requiring de novo nucleotide synthesis), among others, are energetically expensive processes that require large amounts of nutrients. Therefore, immunity competes with other maintenance programmes for energy. The brain stem integrates the energy demand of each organ system, with immunity considered a top priority. The brain stem may "decide" to make a trade-off which involves the induction of a dormancy programme that permits the shutdown of mitochondrial respiration and oxidative phosphorylation in peripheral organs. In the context of acutely decompensated cirrhosis, the consequence of a shutdown of mitochondrial respiration and ATP production would be a dramatic decrease in organ function.

Transcriptomics unveils immune metabolic disruption and a novel biomarker of mortality in patients with HBV-related acute-on-chronic liver failure

Background & Aims

HBV-related acute-on-chronic liver failure (HBV-ACLF) is a complex syndrome associated with high short-term mortality. This study aims to reveal the molecular basis and identify novel HBV-ACLF biomarkers.

Methods

Seventy patients with HBV-ACLF and different short-term (28 days) outcomes underwent transcriptome sequencing using peripheral blood mononuclear cells. Candidate biomarkers were confirmed in two external cohorts using ELISA.

Results

Cellular composition analysis with peripheral blood mononuclear cell transcriptomics showed that the proportions of monocytes, T cells and natural killer cells were significantly correlated with 28-day mortality. Significant metabolic dysregulation of carbohydrate, energy and amino acid metabolism was observed in ACLF non-survivors. V-set and immunoglobulin domain-containing 4 (VSIG4) was the most robust predictor of patient survival (adjusted p = 1.74 × 10-16; variable importance in the projection = 1.21; AUROC = 0.89) and was significantly correlated with pathways involved in the progression of ACLF, including inflammation, oxidative phosphorylation, tricarboxylic acid cycle and T-cell activation/differentiation. Plasma VSIG4 analysis externally validated its diagnostic value in ACLF (compared with chronic liver disease and healthy groups, AUROC = 0.983). The prognostic performance for 28-/90-day mortality (AUROCs = 0.769/0.767) was comparable to that of three commonly used scores (COSSH-ACLFs, 0.867/0.884; CLIF-C ACLFs, 0.840/0.835; MELD-Na, 0.710/0.737). Plasma VSIG4 level, as an independent predictor, could be used to improve the prognostic performance of clinical scores. Risk stratification based on VSIG4 expression levels (>122 μg/ml) identified patients with ACLF at a high risk of death. The generality of VSIG4 in other etiologies was validated.

Conclusions

This study reveals that immune-metabolism disorder underlies poor ACLF outcomes. VSIG4 may be helpful as a diagnostic and prognostic biomarker in clinical practice.

Impact and implications

Acute-on-chronic liver failure (ACLF) is a lethal clinical syndrome associated with high mortality. We found significant immune cell alterations and metabolic dysregulation that were linked to high mortality in patients with HBV-ACLF based on transcriptomics using peripheral blood mononuclear cells. We identified VSIG4 (V-set and immunoglobulin domain-containing 4) as a diagnostic and prognostic biomarker in ACLF, which could specifically identify patients with ACLF at a high risk of death.

Recent progress in understanding mitokines as diagnostic and therapeutic targets in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide and the leading contributor to cancer-related deaths. The progression and metastasis of HCC are closely associated with altered mitochondrial metabolism, including mitochondrial stress response. Mitokines, soluble proteins produced and secreted in response to mitochondrial stress, play an essential immunomodulatory role. Immunotherapy has emerged as a crucial treatment option for HCC. However, a positive response to therapy is typically dependent on the interaction of tumor cells with immune regulation within the tumor microenvironment. Therefore, exploring the specific immunomodulatory mechanisms of mitokines in HCC is essential for improving the efficacy of immunotherapy. This study provides a comprehensive overview of the association between HCC and the immune microenvironment and highlights recent progress in understanding the involvement of mitochondrial function in preserving liver function. In addition, a systematic review of mitokines-mediated immunomodulation in HCC is presented. Finally, the potential diagnostic and therapeutic roles of mitokines in HCC are prospected and summarized. Recent progress in mitokine research represents a new prospect for mitochondrial therapy. Considering the potential of mitokines to regulate immune function, investigating them as a relevant molecular target holds great promise for the diagnosis and treatment of HCC.

Sympathetic nervous activation, mitochondrial dysfunction and outcome in acutely decompensated cirrhosis: the metabolomic prognostic models (CLIF-C MET)

BACKGROUND AND AIMS

Current prognostic scores of patients with acutely decompensated cirrhosis (AD), particularly those with acute-on-chronic liver failure (ACLF), underestimate the risk of mortality. This is probably because systemic inflammation (SI), the major driver of AD/ACLF, is not reflected in the scores. SI induces metabolic changes, which impair delivery of the necessary energy for the immune reaction. This investigation aimed to identify metabolites associated with short-term (28-day) death and to design metabolomic prognostic models.

METHODS

Two prospective multicentre large cohorts from Europe for investigating ACLF and development of ACLF, CANONIC (discovery, n=831) and PREDICT (validation, n=851), were explored by untargeted serum metabolomics to identify and validate metabolites which could allow improved prognostic modelling.

RESULTS

Three prognostic metabolites strongly associated with death were selected to build the models. 4-Hydroxy-3-methoxyphenylglycol sulfate is a norepinephrine derivative, which may be derived from the brainstem response to SI. Additionally, galacturonic acid and hexanoylcarnitine are associated with mitochondrial dysfunction. Model 1 included only these three prognostic metabolites and age. Model 2 was built around 4-hydroxy-3-methoxyphenylglycol sulfate, hexanoylcarnitine, bilirubin, international normalised ratio (INR) and age. In the discovery cohort, both models were more accurate in predicting death within 7, 14 and 28 days after admission compared with MELDNa score (C-index: 0.9267, 0.9002 and 0.8424, and 0.9369, 0.9206 and 0.8529, with model 1 and model 2, respectively). Similar results were found in the validation cohort (C-index: 0.940, 0.834 and 0.791, and 0.947, 0.857 and 0.810, with model 1 and model 2, respectively). Also, in ACLF, model 1 and model 2 outperformed MELDNa 7, 14 and 28 days after admission for prediction of mortality.

CONCLUSIONS

Models including metabolites (CLIF-C MET) reflecting SI, mitochondrial dysfunction and sympathetic system activation are better predictors of short-term mortality than scores based only on organ dysfunction (eg, MELDNa), especially in patients with ACLF.

Acute-on-chronic liver failure: far to go-a review

Acute-on-chronic liver failure (ACLF) has been recognized as a severe clinical syndrome based on the acute deterioration of chronic liver disease and is characterized by organ failure and high short-term mortality. Heterogeneous definitions and diagnostic criteria for the clinical condition have been proposed in different geographic regions due to the differences in aetiologies and precipitating events. Several predictive and prognostic scores have been developed and validated to guide clinical management. The specific pathophysiology of ACLF remains uncertain and is mainly associated with an intense systemic inflammatory response and immune-metabolism disorder based on current evidence. For ACLF patients, standardization of the treatment paradigm is required for different disease stages that may provide targeted treatment strategies for individual needs.

A multistrain probiotic increases the serum glutamine/glutamate ratio in patients with cirrhosis: a metabolomic analysis

To explore the potential mechanisms underlying the effects of a probiotic in cirrhotic patients, we analyzed the blood metabolome using proton nuclear magnetic resonance (1H-NMR) spectroscopy in 32 patients with cirrhosis and cognitive dysfunction or falls. Patients were randomized to receive a multistrain probiotic or placebo for 12 weeks. Among the 54 metabolites identified, the only significant changes in the probiotic group were an increase in glutamine, a decrease in glutamate, and an increase in the glutamine/glutamate ratio. In the placebo group, glutamate increased and the glutamine/glutamate ratio decreased. Our results suggest the multistrain probiotic could influence glutamine/glutamate metabolism, increasing the capacity of ammonia detoxification.

Essential role for albumin in preserving liver cells from TNFα-induced mitochondrial injury

Cytokine-induced inflammation and mitochondrial oxidative stress are key drivers of liver tissue injury. Here, we describe experiments modeling hepatic inflammatory conditions in which plasma leakage leads to large amounts of albumin to reach the interstitium and parenchymal surfaces to explore whether this protein plays a role in preserving hepatocyte mitochondria against the damaging actions of the cytotoxic cytokine tumor necrosis factor alpha (TNFα). Hepatocytes and precision-cut liver slices were cultured in the absence or presence of albumin in the cell media and then exposed to mitochondrial injury with the cytokine TNFα. The homeostatic role of albumin was also investigated in a mouse model of TNFα-mediated liver injury induced by lipopolysaccharide and D-galactosamine (LPS/D-gal). Mitochondrial ultrastructure, oxygen consumption, ATP and reactive oxygen species (ROS) generation, fatty acid β-oxidation (FAO), and metabolic fluxes were assessed by transmission electron microscopy (TEM), high-resolution respirometry, luminescence-fluorimetric-colorimetric assays and NADH/FADH₂ production from various substrates, respectively. TEM analysis revealed that in the absence of albumin, hepatocytes were more susceptible to the damaging actions of TNFα and showed more round-shaped mitochondria with less intact cristae than hepatocytes cultured with albumin. In the presence of albumin in the cell media, hepatocytes also showed reduced mitochondrial ROS generation and FAO. The mitochondria protective actions of albumin against TNFα damage were associated with the restoration of a breakpoint between isocitrate and α-ketoglutarate in the tricarboxylic acid cycle and the upregulation of the antioxidant activating transcription factor 3 (ATF3). The involvement of ATF3 and its downstream targets was confirmed in vivo in mice with LPS/D-gal-induced liver injury, which showed increased hepatic glutathione levels, indicating a reduction in oxidative stress after albumin administration. These findings reveal that the albumin molecule is required for the effective protection of liver cells from mitochondrial oxidative stress induced by TNFα. These findings emphasize the importance of maintaining the albumin levels in the interstitial fluid within the normal range to protect the tissues against inflammatory injury in patients with recurrent hypoalbuminemia.

Evolution of non-thyroidal illness syndrome in acute decompensation of liver cirrhosis and acute-on-chronic liver failure

BACKGROUND AND AIMS

Non-thyroidal illness syndrome (NTIS) is frequent in critically ill patients and associated with adverse outcomes. We aimed to characterize the evolution of NTIS in patients with acute decompensation (AD) of cirrhosis and acute-on-chronic liver failure (ACLF), since NTIS is not well described in these newly defined syndromes.

METHODS

Thyroid hormones (TH) were quantified at baseline in consecutive patients with cirrhosis. In addition, 76 inflammatory mediators were quantified by proximity extension analysis assay in a subgroup of patients. Associations between TH, cirrhosis stage, mortality and inflammation were assessed.

RESULTS

Overall, 437 patients were included, of whom 165 (37.8%), 211 (48.3%), and 61 (14%) had compensated cirrhosis (CC), AD, and ACLF. FT₃ concentrations were lower in AD versus CC, and further decreased in ACLF. Importantly, NTIS was present in 83 (39.3%) patients with AD and in 44 (72.1%) patients with ACLF (P<0.001). Yet, TSH and TSH-based indexes (TSH/FT₃-ratio, thyroid index) showed an U-shaped evolution during progression of cirrhosis, suggesting a partially preserved responsiveness of the hypothalamus and pituitary in AD. Infections were associated with lower FT₃ concentrations in AD, but not in ACLF. Low FT₃ concentrations correlated significantly with 90-day mortality. Both, AD/ACLF and NTIS, were associated with signatures of inflammatory mediators, which were partially non-overlapping.

CONCLUSION

NTIS is frequent already in AD and therefore precedes critically illness in a subgroup of patients with decompensated cirrhosis. This might constitute a new paradigm of TH signaling in cirrhosis, offering opportunities to explore preventive effects of TH in AD.

Research progress on short-term prognosis of acute-on-chronic liver failure

INTRODUCTION

Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized as a severe condition with rapid progression, poor therapeutic response and poor prognosis. Early and timely evaluation of the prognosis is helpful for providing appropriate clinical intervention and prolonging patient survival.

AREAS COVERED

Currently, there are no specific dynamic and comprehensive approaches to assess the prognosis of patients with ACLF. This article reviews the progress in evaluating the short-term prognosis of ACLF to provide future directions for more dynamic prospective large-scale multicenter studies and a basis for individualized and precise treatment for ACLF patients. We searched PubMed and Web of Science with the term 'acute on chronic liver failure' and 'prognosis.' There was no date or language restriction, and our final search was on 26 October 2022.

EXPERT OPINION

ACLF is a dynamic process, and the best prognostic marker is the clinical evolution of organ failure over time. New prognostic markers are developing not only in the fields of genetics and histology but also toward diversification combined with imaging. Determining which patients will benefit from continued advanced life support is a formidable challenge, and accurate short-term prognostic assessments of ACLF are a good approach to addressing this issue.

ALKBH5 attenuates mitochondrial fission and ameliorates liver fibrosis by reducing Drp1 methylation

Mitochondrial metabolism plays a pivotal role in various cellular processes and fibrosis. However, the mechanism underlying mitochondrial metabolic function and liver fibrosis remains poorly understood. In this study, we determined whether mitochondrial metabolism mediates liver fibrosis using cells, animal models, and clinical samples to elucidate the potential effects and underlying mechanism of mitochondrial metabolism in liver fibrosis. We report that AlkB Homolog 5 (ALKBH5) decreases mitochondrial membrane potential (MMP) and oxygen consumption rate (OCR), suppresses mitochondrial fission and hepatic stellate cell (HSC) proliferation and migration and ameliorates liver fibrosis. Enhancement of mitochondrial fission, an essential event during HSC proliferation and migration, is dependent on decreased ALKBH5 expression. Furthermore, we reveal that low ALKBH5 expression is associated with elevated N6-methyladenosine (m⁶A) mRNA levels. Mechanistically, ALKBH5 mediates m⁶A demethylation in the 3'UTR of Drp1 mRNA and induces its translation in a YTH domain family proteins 1 (YTHDF1)-independent manner. Subsequently, in transforming growth factor-β1 (TGF-β1) induced HSC, Dynamin-related protein 1 (Drp1) mediates mitochondrial fission and increases cell proliferation and migration. Decreased Drp1 expression inhibits mitochondrial fission and suppresses HSC proliferation and migration. Notably, human fibrotic liver and heart tissue exhibited enhanced mitochondrial fission; increased YTHDF1, Drp1, alpha-smooth muscle actin (α-SMA) and collagen I expression; decreased ALKBH5 expression and increased liver fibrosis. Our results highlight a novel mechanism by which ALKBH5 suppresses mitochondrial fission and HSC proliferation and migration by reducing Drp1 methylation in an m⁶A-YTHDF1-dependent manner, which may indicate a demethylation-based approach for liver fibrosis diagnosis and therapy.

Down-regulated cylindromatosis enhances NF-κB activation and aggravates inflammation in HBV-ACLF patients

The pathogenesis of liver in patients with hepatitis B virus-associated acute chronic liver failure (HBV-ACLF) remains largely unknown. We aimed to elucidate the molecular mechanism underlying the pathogenesis of liver in HBV-ACLF patients by using multiple approaches including transcriptome analysis. We performed transcriptomic sequencing analysis on the liver of HBV-ACLF patients (n = 6), chronic hepatitis B (n = 6), liver cirrhosis (n = 6) and normal control (n = 5), then explored the potential pathogenesis mechanism in liver specimen from another 48 subjects and further validated the molecular and cellular mechanisms using THP-1 cells. RNA-sequencing data analysis indicated that, among the genes up-regulated in HBV-ACLF, genes related to inflammatory response and chemotaxis accounted for a large proportion of the total DEGs. A number of key chemokines (CCL2, CCL5, CCL20, CXCL5, CXCL6, CXCL8) and NF-ĸB pathway were identified to be robust in the liver samples from HBV-ACLF patients. Interestingly, cylindromatosis (CYLD) was found to be downregulated in the liver of HBV-ACLF patients, in line with the well-established role of CYLD in regulating most of the chemokines and pro-inflammatory cytokines (CCL2, CCL5, CCL20, CXCL5, CXCL6, CXCL8, IL-6, IL-1β) via inhibition of NF-ĸB. Indeed, the knockdown of CYLD resulted in sustained activation of NF-ĸB in macrophages and enhanced chemokines and inflammatory cytokines production, which in turn enhanced chemotactic migration of neutrophil, monocyte, T lymphocytes, and NK cell. In conclusions, down-regulated CYLD aggravated inflammatory cell chemotaxis through enhancing NF-κB activation in HBV-ACLF patients, thereby participating in the pathogenesis of HBV-ACLF injury.