The Role of Monocytes and Macrophages in Acute and Acute-on-Chronic Liver Failure

Safety of treating acute liver injury and failure

INTRODUCTION

Acute liver injury and progression to acute liver failure can be life-threatening conditions that require prompt careful clinical assessment and therapeutic management.

AREAS COVERED

The aim of this article is to review the safety and side effect profile of pharmacological therapies used in the treatment of acute liver injury with specific focus on hepatic toxicity. We performed an extensive literature search with the terms 'acute liver injury,' 'acute liver failure,' 'therapy,' 'safety,' 'adverse reactions' and 'drug induced liver injury.' A thorough discussion of the main drugs and devices used in patients with acute liver injury and acute liver failure, its safety profile and the management of complications associated to therapy of these conditions is presented.

EXPERT OPINION

Several pharmacological approaches are used in acute liver injury and acute liver failure in an empirical basis. Whilst steroids are frequently tried in serious drug-induced liver injury there is concern on a potential harmful effect of these agents because of the higher mortality in patients receiving the drug; hence, statistical approaches such as propensity score matching might help resolve this clinical dilemma. Likewise, properly designed clinical trials using old and new drugs for subjects with serious drug-induced liver injury are clearly needed.

Soluble CD163 Is a Predictor of Mortality in Patients With Decompensated Cirrhosis

Background: Soluble CD163 (sCD163) is a scavenger receptor membrane protein expressed almost exclusively on Kupffer cells and other macrophages. It was found to be associated with the severity of liver cirrhosis. The aim of the present study was to determine whether the novel biomarker sCD163 predicts outcomes in patients with decompensated cirrhosis. Materials and Methods: A single-center, observational, prospective study with 345 decompensated cirrhosis patients was conducted in the Gastroenterology Department between January 2017 and December 2020. Their plasma samples were tested by enzyme-linked immunosorbent assay (ELISA) for sCD163 within 24 hours of admission. These patients were followed up at 28 days, 3 months and 6 months. The independent risk factors were identified with uni- and multivariate logistic regression analyses. We evaluated the predictive performance of the new scoring system (including sCD163) and the original scoring system. Results: The sCD163 level was significantly higher in non-surviving patients than in surviving patients. Positive associations were found between sCD163 levels and the Child-Turcotte-Pugh (CTP), Model for End-Stage Liver Disease (MELD) and albumin-bilirubin (ALBI) scores. Logistic regression confirmed that sCD163 was an independent risk factor for 28-day, 3-month, and 6-month mortality. The areas under the receiver operating characteristic curves (AUROCs) of the use of sCD163 for the prediction of 28-day, 3-month, and 6-month mortality were relatively higher (AUROCs: 0.856; 0.823 and 0.811, respectively). The AUROCs of the new scores obtained by adding sCD163 to the original scoring systems (CTP + sCD163, MELD + sCD163 and ALBI + sCD163) showed that the new scoring systems had better predictive performance than the original scoring systems at all time points (P < 0.001). Conclusion: sCD163 is a prognostic predictor of short-term and long-term outcomes in decompensated cirrhosis patients. Accordingly, the addition of sCD163 to the original clinical scoring systems improved their prognostic performance.

Toxicity of Tetrabromobisphenol A and Its Derivative in the Mouse Liver Following Oral Exposure at Environmentally Relevant Levels

As typical brominated flame retardants (BFRs), tetrabromobisphenol A (TBBPA) and its derivative TBBPA-bis(2,3-dibromopropyl ether) (TBBPA-BDBPE) are ubiquitous in various environmental compartments. However, the potential health risk posed by these compounds, especially at environmentally relevant levels, remains unclear. In this study, using adult male mice, we investigated the toxicity of orally administered TBBPA and TBBPA-BDBPE at an environmentally relevant dose (57 nmol/kg body weight). After a single exposure and daily exposure, we assessed lipid metabolism homeostasis, the transcriptome, and immune cell components in the liver. We found that the single exposure to TBBPA or TBBPA-BDBPE alone increased the number of hepatic macrophages, induced alterations in the levels of lipids, including triacylglycerol and free fatty acids, and caused transcriptome perturbation. The results from the daily administration groups showed that TBBPA and TBBPA-BDBPE both significantly increased the triacylglycerol content; however, the elevation of hepatic macrophages was observed only in the TBBPA-BDBPE treatment group. This study confirmed that environmentally relevant levels of TBBPA and TBBPA-BDBPE are toxic to the liver. Our findings revealed that dysfunction of the liver is a health concern, following exposure to BFRs, even at very low concentrations. The chronic effects induced by TBBPA and its derivatives should be further investigated.

Safety of High-Volume Plasmapheresis in Children With Acute Liver Failure

OBJECTIVES

Paediatric acute liver failure (P-ALF) is a rare condition and is associated with a high mortality rate. Management of P-ALF aims to stabilise vital organ functions and to remove circulating toxins and provide vital plasma factors that are lacking. High-volume plasmapheresis (HVP) removes protein-bound substances and improves survival in adult ALF. It is unknown if this effect can be extrapolated to P-ALF. The aim of this study is to report the safety and feasibility of HVP in P-ALF.

METHODS

Children with P-ALF were offered HVP if bilirubin was higher than 200 μmol/L or if the aetiology was toxic hepatitis. HVP was performed with fresh frozen plasma corresponding to 10% of the body weight on a minimum of 3 consecutive days. Diagnostics, biochemical and clinical data during HVP as well as outcome data after 3 months were collected from 2012 to 2019 and retrospectively analysed.

RESULTS

Sixteen children were treated by HVP and completed at least one series of three treatment sessions with HVP. The only complication seen was an increase in pH > 7.55 in three children within the first 12 hours and was corrected with hydrochloric acid. No bleeding or septic episodes were noted during HVP. Eight children survived without liver transplantation, two survived after successful grafting and a total of six children died. The liver injury unit score between survivors with their own liver and the rest, the two groups was significantly different (P = 0.005).

CONCLUSION

HVP with fresh frozen plasma is feasible and well tolerated in children with P-ALF. No serious adverse events and no procedure-related mortality were observed.

LR12 Promotes Liver Repair by Improving the Resolution of Inflammation and Liver Regeneration in Mice with Thioacetamide- (TAA-) Induced Acute Liver Failure

Background

Triggering receptor expressed on myeloid cells-1 (TREM-1) controls the mobilization of inflammatory cells in response to injury and consequently enhances liver damage. LR12 is a TREM-1 inhibitory peptide. However, the role of LR12 in acute liver failure (ALF) has remained elusive. This study was aimed at indicating whether LR12 could promote liver repair in mice with thioacetamide- (TAA-) induced ALF.

Methods

BALB/c mice were intraperitoneally injected with TAA, followed by intravenous injection of LR12. Damage and regeneration of the liver were assessed. LO2 cells and macrophages were used to assess the therapeutic effects of LR12.

Results

Mice treated with TAA for 24 h developed ALF, while liver inflammation was alleviated after LR12 treatment. Moreover, LR12 promoted hepatocyte regeneration in mice with TAA-induced ALF. In vitro, the supernatant from TAA+LR12-treated macrophages promoted the proliferation of LO2 cells. Cytokine protein microarray analysis suggested that LR12 promoted the secretion of C-C chemokine ligand 20 (CCL20) from macrophages. Besides, neutralization of CCL20 blocked the effects of LR12, thus inhibited the proliferation of LO2 cells in vitro, aggregated the liver inflammation, and restrained hepatocyte regeneration in ALF mice in vivo. Furthermore, we also found that LR12 activated the p38 mitogen-activated protein kinase (MAPK) pathway in hepatocytes through promoting the secretion of CCL20 from macrophages.

Conclusions

LR12 could improve the resolution of inflammation and liver regeneration in mice with TAA-induced ALF by promoting the secretion of CCL20 from macrophages and activating the p38 MAPK pathway. Therefore, LR12 could be an attractive therapeutic target for the treatment of ALF.

Aberrant methylation of UBE2Q1 promoter is associated with poor prognosis of acute-on-chronic hepatitis B pre-liver failure

Acute-on-chronic hepatitis B liver failure (ACHBLF) is one severe liver disease with rapid progression and high mortality. Identification of specific markers for the prediction of ACHBLF has important clinical significance. We explored the feasibility of UBE2Q1 gene promoter methylation as an early prediction and prognosis biomarker of ACHBLF.UBE2Q1 promoter methylation frequency was detected in 60 patients with acute-on-chronic hepatitis B pre-liver failure (Pre-ACHBLF), 40 patients with chronic hepatitis B and 20 cases of healthy control (HC). The UBE2Q1 mRNA was detected by quantitative real-time polymerase chain reaction.The methylation frequency of the UBE2Q1 promoter in pre-ACHBLF patients was 38.33%, which was significantly lower than that in chronic hepatitis B patients (60.00%) and HCs (65.00%). The UBE2Q1 mRNA expression in pre-ACHBLF patients with UBE1Q1 non-methylation was significantly higher than that in patients with UBE1Q1 promoter methylation. Further analysis showed that hypomethylation of the UBE2Q1 promoter was positively correlated with total bilirubin and international normalized ratio levels in patients with pre-ACHBLF, but negatively correlated with PTA level. COX multivariate analysis showed that the model for end-stage liver disease score and UBE2Q1 promoter hypomethylation status were potential early warning factors that can predict the progression of pre-ACHBLF to ACHBLF. The sensitivity and specificity of UBE2Q1 promoter methylation status combined with the model for end-stage liver disease score for early diagnosis of ACHBLF were 92.9% and 75.0%, respectively. The area under the receiver-operating characteristic curve was 0.895.The hypomethylation of UBE2Q1 promoter is associated with severity of Pre-ACHBLF, which could serve as a potential prognostic biomarker for pre-ACHBLF.

Ferulic acid positively modulates the inflammatory response to septic liver injury through the GSK-3β/NF-κB/CREB pathway

AIMS

Ferulic acid (FA) is a component found in plants that has free radical scavenging and liver-protective properties. Acute liver injury (ALI) is a serious complication of sepsis and is closely associated with changes in the levels of inflammatory factors. This study was taken to examine the role of FA in cecal ligation and perforation (CLP)-induced murine ALI and lipopolysaccharide (LPS)-induced cellular ALI models.

MATERIALS AND METHODS

An in vivo ALI model was established by performing CLP surgery on C57BL/6 mice. After the ALI model was established, mice were examined for liver injury, including HE staining to observe tissue sections, the percentage of liver/body weight and inflammatory factor levels. Myeloperoxidase (MPO), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were measured in liver or serum using commercial kits. An in vitro ALI model was established using LPS-stimulated RAW264.7 cells. Cell viability was measured by MTT method and the intracellular levels of IL-10, IL-1β, IL-6, IL-12 and TNF-α inflammatory factors were measured using kits. The expression of GSK-3β, NF-κB and CREB was measured by western blot or immunofluorescence.

KEY FINDINGS

FA pretreatment significantly reduced liver/body weight ratio, decreased MPO, AST and ALT activity, alleviated the inflammatory responses and improved CLP-induced histopathological changes in liver. In addition, in vitro results showed that FA could dose-dependently increase the viability of RAW264.7 cells and decrease the levels of pro-inflammatory factors.

SIGNIFICANCE

In conclusion, our data suggest that FA can ameliorate ALI-induced inflammation via the GSK-3β/NF-κB/CREB pathway, suggesting that FA can be used to protect the liver against ALI.

Patterns of acute decompensation in hospitalized patients with cirrhosis and course of acute-on-chronic liver failure

INTRODUCTION

Recently, based on data from the PREDICT study, the European Foundation for the Study of Chronic Liver Failure (EF-CLIF) consortium proposed pathophysiological/prognostic groups in hospitalized patients with cirrhosis: stable decompensated cirrhosis (SDC), unstable decompensated cirrhosis (UDC), pre-acute-on-chronic liver failure (pre-ACLF), and ACLF. We evaluated the outcomes of these subgroups in a real-life cohort of hospitalized patients with cirrhosis.

METHODS

Patients with cirrhosis developing first AD between 09/2010 and 12/2017 at the Vienna General Hospital were evaluated for this retrospective analysis.

RESULTS

Two hundred and ten patients with cirrhosis (aged 57.6 ± 11.8 years) including n = 45 (21.4%) SDC, n = 100 (47.6%) UDC, n = 28 (13.3%) pre-ACLF, and n = 37 (17.6%) with ACLF were considered. The proposed AD subgroups discriminated between patients with favorable (1-year mortality: SDC: 6.7% and UDC: 19.6%) and dismal prognosis (90-day mortality: pre-ACLF: 42.9%). Interestingly, systemic inflammation gradually increased (e.g., C-reactive protein, SDC: 0.9 mg/dl, vs. UDC: 2.0 mg/dl vs. pre-ACLF: 3.2 mg/dl, p < 0.001) while renal function was progressively deteriorating (creatinine levels, SDC: 0.8 mg/dl vs. UDC: 0.9 mg/dl vs. pre-ACLF: 1.2 mg/dl, p < 0.001) across prognostic subgroups in patients with cirrhosis.

DISCUSSION

The recently proposed pathophysiological/prognostic EF-CLIF subgroups are also reproduceable in a real-life cohort of cirrhotic patients. As ACLF is a common and important complication, patients at risk of pre-ACLF at index AD should be evaluated and if disease proceeds, been treated early and aggressively to avoid excessive mortality.

Worldwide flavor enhancer monosodium glutamate combined with high lipid diet provokes metabolic alterations and systemic anomalies: An overview

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Flavor enhancing high lipid diet acts as silent killer.

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Monosodium glutamate mixed with high lipid diet alters redox-status.

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Monosodium glutamate mixed with high lipid diet induces systemic anomalies.

In this fast-food era, people depend on ready-made foods and engage in minimal physical activities that ultimately change their food habits. Majorities of such foods have harmful effects on human health due to higher percentages of saturated fatty acids, trans-fatty acids, and hydrogenated fats in the form of high lipid diet (HLD). Moreover, food manufacturers add monosodium glutamate (MSG) to enhance the taste and palatability of the HLD. Both MSG and HLD induce the generation of reactive oxygen species (ROS) and thereby alter the redox-homeostasis to cause systemic damage. However, MSG mixed HLD (MH) consumption leads to dyslipidemia, silently develops non-alcoholic fatty liver disease followed by metabolic alterations and systemic anomalies, even malignancies, via modulating different signaling pathways. This comprehensive review formulates health care strategies to create global awareness about the harmful impact of MH on the human body and recommends the daily consumption of more natural foods rich in antioxidants instead of toxic ingredients to counterbalance the MH-induced systemic anomalies.

Sources and prevention of graft infection during long-term ex situ liver perfusion

INTRODUCTION

The use of normothermic liver machine perfusion to repair injured grafts ex situ is an emerging topic of clinical importance. However, a major concern is the possibility of microbial contamination in the absence of a fully functional immune system. Here, we report a standardized approach to maintain sterility during normothermic liver machine perfusion of porcine livers for one week.

METHODS

Porcine livers (n = 42) were procured and perfused with blood at 34°C following aseptic technique and standard operating procedures. The antimicrobial prophylaxis was adapted and improved in a step-wise manner taking into account the pathogens that were detected during the development phase. Piperacillin-Tazobactam was applied as a single dose initially and modified to continuous application in the final protocol. In addition, the perfusion machine was improved to recapitulate partially the host's defense system. The final protocol was tested for infection prevention during one week of perfusion.

RESULTS

During the development phase, microbial contamination occurred in 27 out of 39 (69%) livers with a mean occurrence of growth on 4 ± 1.6 perfusion days. The recovered microorganisms suggested an exogenous source of microbial contamination. The antimicrobial agents (piperacillin/tazobactam) could be maintained above the targeted minimal inhibitory concentration (8-16 mg/L) only with continuous application. In addition to continuous application of piperacillin/tazobactam, partial recapitulation of the host immune system ex situ accompanied by strict preventive measures for contact and air contamination maintained sterility during one week of perfusion.

CONCLUSION

The work demonstrates feasibility of sterility maintenance for one week during ex situ normothermic liver perfusion.

Monocyte dysregulation: consequences for hepatic infections

Liver disorders due to infections are a substantial health concern in underdeveloped and industrialized countries. This includes not only hepatotropic viruses (e.g., hepatitis B, hepatitis C) but also bacterial and parasitic infections such as amebiasis, leishmaniasis, schistosomiasis, or echinococcosis. Recent studies of the immune mechanisms underlying liver disease show that monocytes play an essential role in determining patient outcomes. Monocytes are derived from the mononuclear phagocyte lineage in the bone marrow and are present in nearly all tissues of the body; these cells function as part of the early innate immune response that reacts to challenge by external pathogens. Due to their special ability to develop into tissue macrophages and dendritic cells and to change from an inflammatory to an anti-inflammatory phenotype, monocytes play a pivotal role in infectious and non-infectious liver diseases: they can maintain inflammation and support resolution of inflammation. Therefore, tight regulation of monocyte recruitment and termination of monocyte-driven immune responses in the liver is prerequisite to appropriate healing of organ damage. In this review, we discuss monocyte-dependent immune mechanisms underlying hepatic infectious disorders. Better understanding of these immune mechanisms may lead to development of new interventions to treat acute liver disease and prevent progression to organ failure.

Combined Effects of Myeloid Cells in the Neuroblastoma Tumor Microenvironment

Despite multimodal treatment, survival chances for high-risk neuroblastoma patients remain poor. Immunotherapeutic approaches focusing on the activation and/or modification of host immunity for eliminating tumor cells, such as chimeric antigen receptor (CAR) T cells, are currently in development, however clinical trials have failed to reproduce the preclinical results. The tumor microenvironment is emerging as a major contributor to immune suppression and tumor evasion in solid cancers and thus has to be overcome for therapies relying on a functional immune response. Among the cellular components of the neuroblastoma tumor microenvironment, suppressive myeloid cells have been described as key players in inhibition of antitumor immune responses and have been shown to positively correlate with more aggressive disease, resistance to treatments, and overall poor prognosis. This review article summarizes how neuroblastoma-driven inflammation induces suppressive myeloid cells in the tumor microenvironment and how they in turn sustain the tumor niche through suppressor functions, such as nutrient depletion and generation of oxidative stress. Numerous preclinical studies have suggested a range of drug and cellular therapy approaches to overcome myeloid-derived suppression in neuroblastoma that warrant evaluation in future clinical studies.

Macrophages in Chronic Liver Failure: Diversity, Plasticity and Therapeutic Targeting

Chronic liver injury results in immune-driven progressive fibrosis, with risk of cirrhosis development and impact on morbidity and mortality. Persistent liver cell damage and death causes immune cell activation and inflammation. Patients with advanced cirrhosis additionally experience pathological bacterial translocation, exposure to microbial products and chronic engagement of the immune system. Bacterial infections have a high incidence in cirrhosis, with spontaneous bacterial peritonitis being the most common, while the subsequent systemic inflammation, organ failure and immune dysregulation increase the mortality risk. Tissue-resident and recruited macrophages play a central part in the development of inflammation and fibrosis progression. In the liver, adipose tissue, peritoneum and intestines, diverse macrophage populations exhibit great phenotypic and functional plasticity determined by their ontogeny, epigenetic programming and local microenvironment. These changes can, at different times, promote or ameliorate disease states and therefore represent potential targets for macrophage-directed therapies. In this review, we discuss the evidence for macrophage phenotypic and functional alterations in tissue compartments during the development and progression of chronic liver failure in different aetiologies and highlight the potential of macrophage modulation as a therapeutic strategy for liver disease.

Protective Effects of Taraxacum officinale L. (Dandelion) Root Extract in Experimental Acute on Chronic Liver Failure

BACKGROUND

Taraxacum officinale (TO) or dandelion has been frequently used to prevent or treat different liver diseases because of its rich composition in phytochemicals with demonstrated effect against hepatic injuries. This study aimed to investigate the possible preventing effect of ethanolic TO root extract (TOERE) on a rat experimental acute on chronic liver failure (ACLF) model.

METHODS

Chronic liver failure (CLF) was induced by human serum albumin, and ACLF was induced in CLF by D-galactosamine and lipopolysaccharide (D-Gal-LPS). Five groups (n = 5) of male Wistar rats (200-250 g) were used: ACLF, ACLF-silymarin (200 mg/kg b.w./day), three ACLF-TO administered in three doses (200 mg, 100 mg, 50 mg/kg b.w./day).

RESULTS

The in vivo results showed that treatment with TOERE administered in three chosen doses before ACLF induction reduced serum liver injury markers (AST, ALT, ALP, GGT, total bilirubin), renal tests (creatinine, urea), and oxidative stress tests (TOS, OSI, MDA, NO, 3NT). Histopathologically, TOERE diminished the level of liver tissue injury and 3NT immunoexpression.

CONCLUSIONS

This paper indicated oxidative stress reduction as possible mechanisms for the hepatoprotective effect of TOERE in ACLF and provided evidence for the preventive treatment.

Adipocyte Fatty Acid-Binding Protein as a Predictor of Outcome in Alcohol-induced Acute-On-Chronic Liver Failure

BACKGROUND

Alcohol is the leading cause of acute-on-chronic liver failure (ACLF). Several severity scores predict the outcome of ACLF. However, there is a lack of simple biomarkers in predicting the outcome of these sick patients. Fatty acid-binding proteins (FABPs) are small cytosolic proteins that play a major role in lipid metabolism, energy homeostasis, and inflammation, but, have not been investigated in alcohol-induced ACLF (A-ACLF).

OBJECTIVES

The primary objective was to assess the correlation between serum adipocyte-FABP (A-FABP) and liver-FABP (L-FABP) levels on mortality at day 90. Secondary objectives were to compare the levels between controls and A-ACLF, correlate L-FABP, and A-FABP levels on the development of organ failure/sepsis at day 90.

METHODS

In this prospective observational pilot study, we included patients with A-ACLF and age-matched healthy controls. FABP's were analyzed by enzyme-linked immunosorbent assay method. The patients were followed up for 90 days.

RESULTS

Twenty-five patients with A-ACLF (mean age: 40years; mean model for end-stage liver disease NA: 29.8; median Modified Maddrey's discriminant function [mDF]: 95) and 12 controls (mean age: 36.83yrs) were included in the study. A-FABP and L-FABP levels were significantly high in patients with A-ACLF than controls. Forty-four percent of patients with A-ACLF developed sepsis, 48% developed organ failure, and 44% expired by day 90. On multivariate Cox regression analysis, A-FABP (hazard ratio [HR]: 1.27 [1.08-1.5]; P = 0.003), Asian Pacific Association for the Study of Liver ACLF research consortium score (HR: 3.3[1.15-9.54]; P = 0.02), L-FABP (HR: 0.69 [0.52-0.91]; P = 0.009), and serum protein levels (HR: 0.03 [0.003-0.36]; P = 0.005) predicted mortality. A-FABP (1.17 [1.07-1.29]; P = 0.001), and serum bilirubin (1.05 [0.99-1.12]; P = 0.06) predicted development of organ failure, and only mDF (HR: 1.04 [1.01-1.07]; P = 0.009) predicted the development of sepsis on multivariate analysis. Fifteen patients received steroid therapy, of which 13.34% were nonresponders.

CONCLUSIONS

In a selected group of patients with A-ACLF, A-FABP is highly sensitive at predicting mortality and outcome. If validated in a large, diverse sample, A-FABP can be used as a simple biomarker for prognostication in A-ACLF.

[Application of double plasma molecular adsorption system in children with acute liver failure]

OBJECTIVE

To study the efficacy and safety of double plasma molecular absorption system (DPMAS) in the treatment of pediatric acute liver failure (PALF).

METHODS

A prospective analysis was performed on the medical data of children with PALF who were hospitalized in the Intensive Care Unit (ICU), Hunan Children's Hospital, from March 2018 to June 2020. The children were randomly divided into two groups:plasma exchange group (PE group) and DPMAS group (n=18 each). The two groups were compared in terms of clinical indices after treatment, laboratory markers before and after treatment, and adverse events after treatment.

RESULTS

Compared with the PE group, the DPMAS group had a significantly lower number of times of artificial liver support therapy and a significantly shorter duration of ICU stay (P < 0.05), while there was no significant difference in the 12-week survival rate between the two groups (P > 0.05). There was no significant difference in laboratory markers between the two groups before treatment (P > 0.05). After treatment, both groups had reductions in the levels of total bilirubin, interleukin-6, and tumor necrosis factor-α, and the DPMAS group had significantly greater reductions than the PE group (P < 0.05). Both groups had a significant reduction in alanine aminotransferase (P < 0.05), while there was no significant difference between the two groups (P > 0.05). The PE group had a significant increase in albumin, while the DPMAS group had a significant reduction in albumin (P < 0.05). The PE group had a significant reduction in prothrombin time, while the DPMAS group had a significant increase in prothrombin time (P < 0.05). There was no significant difference between the two groups in the rebound rate of total bilirubin and the overall incidence rate of adverse events after treatment (P > 0.05).

CONCLUSIONS

DPMAS is safe and effective in the treatment of PALF and can thus be used as an alternative to artificial liver support therapy.

PD-1 blockade improves Kupffer cell bacterial clearance in acute liver injury

Patients with acute liver failure (ALF) have systemic innate immune suppression and increased susceptibility to infections. Programmed cell death 1 (PD-1) expression by macrophages has been associated with immune suppression during sepsis and cancer. We therefore examined the role of the programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) pathway in regulating Kupffer cell (KC) inflammatory and antimicrobial responses in acetaminophen-induced (APAP-induced) acute liver injury. Using intravital imaging and flow cytometry, we found impaired KC bacterial clearance and systemic bacterial dissemination in mice with liver injury. We detected increased PD-1 and PD-L1 expression in KCs and lymphocyte subsets, respectively, during injury resolution. Gene expression profiling of PD-1⁺ KCs revealed an immune-suppressive profile and reduced pathogen responses. Compared with WT mice, PD-1–deficient mice and anti–PD-1–treated mice with liver injury showed improved KC bacterial clearance, a reduced tissue bacterial load, and protection from sepsis. Blood samples from patients with ALF revealed enhanced PD-1 and PD-L1 expression by monocytes and lymphocytes, respectively, and that soluble PD-L1 plasma levels could predict outcomes and sepsis. PD-1 in vitro blockade restored monocyte functionality. Our study describes a role for the PD-1/PD-L1 axis in suppressing KC and monocyte antimicrobial responses after liver injury and identifies anti–PD-1 immunotherapy as a strategy to reduce infection susceptibility in ALF.

Inhibition of androgen/AR signaling inhibits diethylnitrosamine (DEN) induced tumour initiation and remodels liver immune cell networks

A promotional role for androgen receptor (AR) signaling in hepatocellular carcinogenesis is emerging. In pre-clinical models, including diethylnitrosamine- (DEN-) induced hepatocellular carcinoma (HCC), anti-androgen therapies delay hepatocarcinogenesis. However, pharmacologic anti-androgen therapy in advanced HCC patients fails, suggesting that AR plays a role in HCC onset. This study aims to characterize AR expression and function throughout DEN-induced liver inflammation and carcinogenesis and evaluate the efficacy of prophylactic AR antagonism to prevent hepatocarcinogenesis. We demonstrate that pharmacologic AR antagonism with enzalutamide inhibits hepatocellular carcinogenesis. With enzalutamide treatment, we observe decreased CYP2E1 expression, reducing DEN-induced hepatocyte death and DNA ethyl-adducts. AR protein expression analyses show that DEN causes an initial upregulation of AR in portal fibroblasts and leukocytes, but not hepatocytes, suggesting that hepatocyte-autonomous AR signaling is not essential for DEN-induced carcinogenesis. Ablating androgen signaling by surgical castration reduced pre-carcinogen Kupffer cell populations but did not alter DEN-mediated immune cell recruitment nor AR expression. In this study, we identified that anti-androgen interventions modulate mutagenic DNA adducts, tumour initiation, and immune cell composition. Additionally, we find that AR expression in hepatocytes is not present during nor required for early DEN-mediated carcinogenesis.

Fatal acute-on-chronic liver failure in amiodarone-related steatohepatitis: a case report

BACKGROUND

Amiodarone is an antiarrhythmic drug that has been recognized to induce hepatotoxicity. We report a case of acute-on-chronic liver failure (ACLF) in a patient who was receiving amiodarone for more than 2 years. The patient developed cirrhosis and suppurative microabscesses of the liver and died of progressive liver failure.

CASE PRESENTATION

A 69-year-old woman with risk factors for nonalcoholic fatty liver disease (NAFLD) was treated with oral amiodarone at a daily dose of 400 mg for more than 2 years, until she developed epigastralgia and vomiting. Initial laboratory findings included leukocytosis and elevated liver enzymes. Images of abdominal computed tomography scan revealed diffusely increased hepatic attenuation density (in contrast to decreased density in NAFLD), hepatomegaly, periportal edema, and ascites. Liver biopsy targeting the hotspot identified through positron emission tomography confirmed the diagnosis of amiodarone-associated chronic steatohepatitis and superimposed microabscesses. The patient died of progressive ACLF despite intensive supportive care.

CONCLUSION

Accumulation of amiodarone can result in chronic liver disease and pose an additional risk of ACLF following infection.

Circulating Bile Acids in Liver Failure Activate TGR5 and Induce Monocyte Dysfunction

BACKGROUND & AIMS

Retention of bile acids in the blood is a hallmark of liver failure. Recent studies have shown that increased serum bile acid levels correlate with bacterial infection and increased mortality. However, the mechanisms by which circulating bile acids influence patient outcomes still are elusive.

METHODS

Serum bile acid profiles in 33 critically ill patients with liver failure and their effects on Takeda G-protein-coupled receptor 5 (TGR5), an immunomodulatory receptor that is highly expressed in monocytes, were analyzed using tandem mass spectrometry, novel highly sensitive TGR5 bioluminescence resonance energy transfer using nanoluciferase (NanoBRET, Promega Corp, Madison, WI) technology, and in vitro assays with human monocytes.

RESULTS

Twenty-two patients (67%) had serum bile acids that led to distinct TGR5 activation. These TGR5-activating serum bile acids severely compromised monocyte function. The release of proinflammatory cytokines (eg, tumor necrosis factor α or interleukin 6) in response to bacterial challenge was reduced significantly if monocytes were incubated with TGR5-activating serum bile acids from patients with liver failure. By contrast, serum bile acids from healthy volunteers did not influence cytokine release. Monocytes that did not express TGR5 were protected from the bile acid effects. TGR5-activating serum bile acids were a risk factor for a fatal outcome in patients with liver failure, independent of disease severity.

CONCLUSIONS

Depending on their composition and quantity, serum bile acids in liver failure activate TGR5. TGR5 activation leads to monocyte dysfunction and correlates with mortality, independent of disease activity. This indicates an active role of TGR5 in liver failure. Therefore, TGR5 and bile acid metabolism might be promising targets for the treatment of immune dysfunction in liver failure.

[Application of double plasma molecular adsorption system in children with acute liver failure]

OBJECTIVE

To study the efficacy and safety of double plasma molecular absorption system (DPMAS) in the treatment of pediatric acute liver failure (PALF).

METHODS

A prospective analysis was performed on the medical data of children with PALF who were hospitalized in the Intensive Care Unit (ICU), Hunan Children's Hospital, from March 2018 to June 2020. The children were randomly divided into two groups:plasma exchange group (PE group) and DPMAS group (n=18 each). The two groups were compared in terms of clinical indices after treatment, laboratory markers before and after treatment, and adverse events after treatment.

RESULTS

Compared with the PE group, the DPMAS group had a significantly lower number of times of artificial liver support therapy and a significantly shorter duration of ICU stay (P < 0.05), while there was no significant difference in the 12-week survival rate between the two groups (P > 0.05). There was no significant difference in laboratory markers between the two groups before treatment (P > 0.05). After treatment, both groups had reductions in the levels of total bilirubin, interleukin-6, and tumor necrosis factor-α, and the DPMAS group had significantly greater reductions than the PE group (P < 0.05). Both groups had a significant reduction in alanine aminotransferase (P < 0.05), while there was no significant difference between the two groups (P > 0.05). The PE group had a significant increase in albumin, while the DPMAS group had a significant reduction in albumin (P < 0.05). The PE group had a significant reduction in prothrombin time, while the DPMAS group had a significant increase in prothrombin time (P < 0.05). There was no significant difference between the two groups in the rebound rate of total bilirubin and the overall incidence rate of adverse events after treatment (P > 0.05).

CONCLUSIONS

DPMAS is safe and effective in the treatment of PALF and can thus be used as an alternative to artificial liver support therapy.

Glutathione-S-transferase alpha-4 in Hippocampus abdominalis (big-belly seahorse): Molecular characterization, antioxidant properties, and its potent immune response

Glutathione-S-transferase (GST) is a key enzyme in the phase-II detoxification process and is a biomarker of oxidative stress. In this study, we analyzed the molecular, biochemical, and antioxidant properties of GST alpha-4 from Hippocampus abdominalis (HaGSTA-4). Also, the spatial and temporal expression of HaGSTA-4 upon immune challenge with abiotic and biotic stimulants were evaluated. The HaGSTA-4 ORF encodes 223 amino acids with a molecular weight of 25.7 kDa, and an estimated isoelectric point (pI) of 8.47. It consists of the GST_C superfamily and thioredoxin-like superfamily domain. The phylogenetic tree revealed that HaGSTA-4 is evolutionarily conserved with its GST alpha class counterparts. From pairwise alignment, the highest values of identity (78.5%) and similarity (85.7%) were with Parambassis ranga GSTA-4. Protein rHaGSTA-4 exhibited the highest conjugation activity towards 1-chloro-2,4-dinitrobenzene (CDNB) at pH 7 and 20 °C. A disk diffusion assay showed that rHaGSTA-4 significantly protects cells from the stress of exposure to ROS inducers such as CuSO₄, CdCl₂, and ZnCl₂. Furthermore, overexpressed HaGSTA-4 defended cells against oxidative stress caused by H₂O₂; evidence of selenium-independent peroxidase activity. From qPCR, the tissue-specific expression profile demonstrates that HaGSTA-4 is most highly expressed in the kidney, followed by the intestine and stomach, among fourteen different tissues extracted from healthy seahorses. The mRNA expression profile of HaGSTA-4 upon immune challenge varied depending on the tissue and the time after challenge. Altogether, this study suggests that HaGSTA-4 may be involved in protection against oxidative stress, in immune defense regulation, and xenobiotic metabolism.

Development of Lipid Nanoparticles for the Delivery of Macromolecules Based on the Molecular Design of pH-Sensitive Cationic Lipids

Considerable efforts have been made on the development of lipid nanoparticles (LNPs) for delivering of nucleic acids in LNP-based medicines, including a first-ever short interfering RNA (siRNA) medicine, Onpattro, and the mRNA vaccines against the coronavirus disease 2019 (COVID-19), which have been approved and are currently in use worldwide. The successful rational design of ionizable cationic lipids was a major breakthrough that dramatically increased delivery efficiency in this field. The LNPs would be expected to be useful as a platform technology for the delivery of various therapeutic modalities for genome editing and even for undiscovered therapeutic mechanisms. In this review, the current progress of my research, including the molecular design of pH-sensitive cationic lipids, their applications for various tissues and cell types, and for delivering various macromolecules, including siRNA, antisense oligonucleotide, mRNA, and the clustered regularly interspaced short palindromic repeats (CRISPR)-associated (Cas) system will be described. Mechanistic studies regarding relationships between the physicochemical properties of LNPs, drug delivery, and biosafety are also summarized. Furthermore, current issues that need to be addressed for next generation drug delivery systems are discussed.

Liver-lung interactions in acute respiratory distress syndrome

Patients with liver diseases are at high risk for the development of acute respiratory distress syndrome (ARDS). The liver is an important organ that regulates a complex network of mediators and modulates organ interactions during inflammatory disorders. Liver function is increasingly recognized as a critical determinant of the pathogenesis and resolution of ARDS, significantly influencing the prognosis of these patients. The liver plays a central role in the synthesis of proteins, metabolism of toxins and drugs, and in the modulation of immunity and host defense. However, the tools for assessing liver function are limited in the clinical setting, and patients with liver diseases are frequently excluded from clinical studies of ARDS. Therefore, the mechanisms by which the liver participates in the pathogenesis of acute lung injury are not totally understood. Several functions of the liver, including endotoxin and bacterial clearance, release and clearance of pro-inflammatory cytokines and eicosanoids, and synthesis of acute-phase proteins can modulate lung injury in the setting of sepsis and other severe inflammatory diseases. In this review, we summarized clinical and experimental support for the notion that the liver critically regulates systemic and pulmonary responses following inflammatory insults. Although promoting inflammation can be detrimental in the context of acute lung injury, the liver response to an inflammatory insult is also pro-defense and pro-survival. A better understanding of the liver–lung axis will provide valuable insights into new diagnostic targets and therapeutic strategies for clinical intervention in patients with or at risk for ARDS.

Hepatoprotective effect of apolipoprotein A4 against carbon tetrachloride induced acute liver injury through mediating hepatic antioxidant and inflammation response in mice

Apolipoprotein A4 (ApoA4) regulates lipid and glucose metabolism and exerts anti-inflammatory effects in atherogenesis and colitis. The present study explored the presumed protective role of ApoA4 in carbon tetrachloride (CCl4)-induced acute liver injury (ALI) in mice. The ALI model in wild type (WT), ApoA4 knock-out (ApoA4-KO) and ApoA4 transgenic (ApoA4-TG) mice was induced by a single intraperitoneal administration of CCl4. Liver and blood were harvested from mice to assess liver functions, immunohistological changes, immune cell populations and cytokine profiles. ApoA4 deficiency aggravated, and ApoA4 overexpression alleviated CCl4-inflicted liver damage by controlling levels of anti-oxidant enzymes. ApoA4 deletion increased the recruitment of monocytes/macrophages into the injured liver and upregulated the plasma levels of IL-6, TNF-α and MCP-1, but lower IL-10 and IFN-γ. ApoA4 over-expression rescued this effect and resulted in lower percentages of monocytes/macrophages and dendritic cells, the ratio of blood pro-inflammatory to anti-inflammatory monocytes and reduced plasma concentrations of IL-6, but enhanced IL-10 and IFN-γ. We propose ApoA4 as a potential new therapeutic target for the management of liver damage.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Cell Therapy for Liver Disease: From Promise to Reality

Over the last decade, there has been a considerable progress in the development of cell therapy products for the treatment of liver diseases. The quest to generate well-defined homogenous cell populations with defined mechanism(s) of action has enabled the progression from use of autologous bone marrow stem cells comprising of heterogeneous cell populations to allogeneic cell types such as monocyte-derived macrophages, regulatory T cells, mesenchymal stromal cells, macrophages, etc. There is growing evidence regarding the multiple molecular mechanisms pivotal to various therapeutic effects and hence, careful selection of cell therapy product for the desired putative effects is crucial. In this review, we have presented an overview of the cell therapies that have been developed thus far, with preclinical and clinical evidence for their use in liver disease. Limitations associated with these therapies have also been discussed. Despite the advances made, there remain multiple challenges to overcome before cell therapies can be considered as viable treatment options, and these include larger scale clinical trials, scalable production of cells according to good manufacturing practice standards, pathways for delivery of cell therapy within hospital environments, and costs associated with the production.

Hepatic macrophages in liver homeostasis and diseases-diversity, plasticity and therapeutic opportunities

Macrophages, which are key cellular components of the liver, have emerged as essential players in the maintenance of hepatic homeostasis and in injury and repair processes in acute and chronic liver diseases. Upon liver injury, resident Kupffer cells (KCs) sense disturbances in homeostasis, interact with hepatic cell populations and release chemokines to recruit circulating leukocytes, including monocytes, which subsequently differentiate into monocyte-derived macrophages (MoMϕs) in the liver. Both KCs and MoMϕs contribute to both the progression and resolution of tissue inflammation and injury in various liver diseases. The diversity of hepatic macrophage subsets and their plasticity explain their different functional responses in distinct liver diseases. In this review, we highlight novel findings regarding the origins and functions of hepatic macrophages and discuss the potential of targeting macrophages as a therapeutic strategy for liver disease.

Invasive aspergillosis complication in yellow fever vaccine induced viscerotropic disease

Invasive aspergillosis (IA) usually occurs in immunocompromised hosts, but in the last decade IA has emerged in critically ill non-neutropenic patients, as those with severe Influenza and Chronic Obstructive Pulmonary Disease (COPD). We report an unusual fatal case of disseminated IA in a non-immunocompromised patient following yellow fever vaccine-associated viscerotropic disease.

Systematic analysis on multiple Gene Expression Omnibus data sets reveals fierce immune response in hepatitis B virus-related acute liver failure

Acute liver failure (ALF) caused by hepatitis B virus (HBV) is common type of liver failure in the world, with high morbidity and mortality rates. However, the prevalence, genetic background and factors determining the development of HBV‐related ALF are rarely studied. In this study, we examined three Gene Expression Omnibus (GEO) data sets by bioinformatics analysis to identify differentially expressed genes (DEGs), key biological processes and pathways. Immune infiltration analysis showed high immune cells infiltration in HBV‐related ALF tissue. We then confirmed natural killer cells and macrophages infiltration in clinical samples by immunohistochemistry assay, implying these cells play a significant role in HBV‐ALF. We found 1277 genes were co‐up‐regulated and that 1082 genes were co‐down‐regulated in the 3 data sets. Inflammation‐related pathways were enriched in the co‐up‐regulated genes and synthetic metabolic pathways were enriched in the co‐down‐regulated genes. WGCNA also revealed a key module enriching in immune inflammation response and identified 10 hub genes, differentially expressed in an independent data set. In conclusion, we identified fierce immune inflammatory response to elucidate the immune‐driven mechanism of HBV‐ALF and 10 hub genes based on gene expression profiles.

Profiling the Course of Resolving vs. Persistent Inflammation in Human Monocytes: The Role of IL-1 Family Molecules

Monocytes and macrophages have a central role in all phases of an inflammatory reaction. To understanding the regulation of monocyte activation during a physiological or pathological inflammation, we propose two in vitro models that recapitulate the different phases of the reaction (recruitment, initiation, development, and resolution vs. persistence of inflammation), based on human primary blood monocytes exposed to sequential modifications of microenvironmental conditions. These models exclusively describe the functional development of blood-derived monocytes that first enter an inflammatory site. All reaction phases were profiled by RNA-Seq, and the two models were validated by studying the modulation of IL-1 family members. Genes were differentially modulated, and distinct clusters were identified during the various phases of inflammation. Pathway analysis revealed that both models were enriched in pathways involved in innate immune activation. We observe that monocytes acquire an M1-like profile during early inflammation, and switch to a deactivated M2-like profile during both the resolving and persistent phases. However, during persistent inflammation they partially maintain an M1 profile, although they lose the ability to produce inflammatory cytokines compared to M1 cells. The production of IL-1 family molecules by ELISA reflected the transcriptomic profiles in the distinct phases of the two inflammatory reactions. Based on the results, we hypothesize that persistence of inflammatory stimuli cannot maintain the M1 activated phenotype of incoming monocytes for long, suggesting that the persistent presence of M1 cells and effects in a chronically inflamed tissue is mainly due to activation of newly incoming cells. Moreover, being IL-1 family molecules mainly expressed and secreted by monocytes during the early stages of the inflammatory response (within 4-14 h), and the rate of their production decreasing during the late phase of both resolving and persistent inflammation, we suppose that IL-1 factors are key regulators of the acute defensive innate inflammatory reaction that precedes establishment of longer-term adaptive immunity, and are mainly related to the presence of recently recruited blood monocytes. The well-described role of IL-1 family cytokines and receptors in chronic inflammation is therefore most likely dependent on the continuous influx of blood monocytes into a chronically inflamed site.

Elevated neopterin levels are associated with acute-on-chronic liver failure and mortality in patients with liver cirrhosis

BACKGROUND

Macrophage activation plays a central role in hepatic and systemic inflammation and is involved in the pathogenesis of acute-on-chronic liver failure (ACLF).

AIMS

This study aimed to investigate neopterin levels in patients admitted for acute decompensation (AD) of cirrhosis, evaluating its relationship with ACLF and prognosis.

METHODS

This prospective cohort study included 205 adult subjects hospitalized for AD of cirrhosis. Twenty-one healthy subjects and 89 patients with stable cirrhosis were evaluated as controls.

RESULTS

Circulating neopterin was higher in AD as compared to stable cirrhosis and healthy controls (p<0.001). ACLF was independently associated with higher neopterin levels (OR 1.015, 95% CI 1.002-1.028, p = 0.025). In the multivariate Cox regression analysis, neopterin levels (HR = 1.002, IC 95% 1.000-1.004, p = 0.041), Child-Pugh class C, and ACLF were predictors of 30-day survival. Among patients with ACLF, the Kaplan-Meier survival probability was 71.4% in those with neopterin levels < 25 nmol/L and 31.0% if neopterin ≥ 25 nmol/L (p<0.001).

CONCLUSIONS

Higher circulating neopterin was associated with ACLF in patients hospitalized for AD of cirrhosis. Neopterin levels were also independently predictors of high short-term mortality, especially among patients with ACLF, and could represent a useful biomarker of macrophage activation in clinical practice.

Functional activity of peripheral blood monocytes in patients with opisthorchiasis coupled to liver fibrosis intensity

The aim is to examine activity of peripheral blood monocytes from patients with opisthorchiasis coupled to intensity of liver fibrosis. Materials and Methods. A total of 74 patients with chronic opisthorchiasis (39 males and 35 females, average age 42.3 years) and 32 apparently healthy subjects (17 males and 15 females, average age 41.5 years) aged 24 to 60 years were enrolled. Opisthorchiasis was mainly diagnosed by parasitological assays to detect adult parasite eggs or bodies in duodenal contents and/or feces in all 74 patients. Liver fibrosis was assessed by elastometry according to the METAVIR scale. Functional activity of peripheral blood monocytes was performed in all patients with opisthorchiasis and healthy individuals from the control group by chemiluminescent analysis to measure intensity of reactive oxygen species production in lucigenin- and luminol-dependent spontaneous and zymosan-induced reactions. Results. Liver fibrosis F2 and F3—F4 stage according to METAVIR scale was found in 20.3% and 17.6% of patients with opisthorchiasis, respectively. While analyzing total pool of reactive oxygen species in the luminol-dependent process in patients with opisthorchiasis, a significantly decreased monocyte functional activity was observed as compared to healthy subjects that was evidenced by significantly decreased maximum intensity of produced reactive oxygen species as well as area under the chemiluminescence curve both in spontaneous and zymosan-induced reaction. Such parameters in liver fibrosis F3—F4 compared to F0—F1 in zymosan-induced response were lowered. Monocyte functional activity in spontaneous luminol-dependent reaction did not differ significantly depending on liver fibrosis intensity in patients with opisthorchiasis. The phagocytosis activation index in patients with opisthorchiasis with liver fibrosis F3—F4 compared to F0—F1 and F2 stage was lower. Similar changes were observed in the lucigenin-dependent reaction. Conclusion. The data obtained undoubtedly provide promising evidence to interpret the mechanisms behind liver fibrosis in patients with opisthorchiasis and create new opportunities for development of diagnostic and therapeutic technologies.

Systemic MCP-1 Levels Derive Mainly From Injured Liver and Are Associated With Complications in Cirrhosis

Background and Aims: Monocyte chemotactic protein-1 (MCP-1) is a potent chemoattractant for monocytes. It is involved in pathogenesis of several inflammatory diseases. Hepatic MCP-1 is a readout of macrophage activation. While inflammation is a major driver of liver disease progression, the origin and role of circulating MCP-1 as a biomarker remains unclear.

Methods: Hepatic CC-chemokine ligand 2 (CCL2) expression and F4/80 staining for Kupffer cells were measured and correlated in a mouse model of chronic liver disease (inhalative CCl₄ for 7 weeks). Next, hepatic RNA levels of CCL2 were measured in explanted livers of 39 patients after transplantation and correlated with severity of disease. Changes in MCP-1 were further evaluated in a rat model of experimental cirrhosis and acute-on-chronic liver failure (ACLF). Finally, we analyzed portal and hepatic vein levels of MCP-1 in patients receiving transjugular intrahepatic portosystemic shunt insertion for complications of portal hypertension.

Results: In this mouse model of fibrotic hepatitis, hepatic expression of CCL2 (P = 0.009) and the amount of F4/80 positive cells in the liver (P < 0.001) significantly increased after induction of hepatitis by CCl₄ compared to control animals. Moreover, strong correlation of hepatic CCL2 expression and F4/80 positive cells were seen (P = 0.023). Furthermore, in human liver explants, hepatic transcription levels of CCL2 correlated with the MELD score of the patients, and thus disease severity (P = 0.007). The experimental model of ACLF in rats revealed significantly higher levels of MCP-1 plasma (P = 0.028) and correlation of hepatic CCL2 expression (R = 0.69, P = 0.003). Particularly, plasma MCP-1 levels did not correlate with peripheral blood monocyte CCL2 expression. Finally, higher levels of MCP-1 were observed in the hepatic compared to the portal vein (P = 0.01) in patients receiving TIPS. Similarly, a positive correlation of MCP-1 with Child-Pugh score was observed (P = 0.018). Further, in the presence of ACLF, portal and hepatic vein levels of MCP-1 were significantly higher compared to patients without ACLF (both P = 0.039).

Conclusion: Circulating levels of MCP-1 mainly derive from the injured liver and are associated with severity of liver disease. Therefore, liver macrophages contribute significantly to disease progression. Circulating MCP-1 may reflect the extent of hepatic macrophage activation.

NLRP3 inflammasome and related cytokines reflect the immune status of patients with HBV-ACLF

BACKGROUND

The NLRP3 inflammasome has been suggested to play a crucial role in host antiviral defense, including against hepatitis B virus (HBV) infection. In the present study, we measured expression of NLRP3 and its related cytokines in patients with different stages of HBV-related acute-on-chronic liver failure (HBV-ACLF), a pattern of end-stage liver disease that occurs frequently in patients with chronic HBV (CHB) infection or HBV-related cirrhosis.

METHODS

A total of 75 subjects including 30 HBV-ACLF patients, 30 CHB patients, and 15 healthy controls (HCs) were enrolled. The NLRP3 inflammasome and its components (caspase-1, interleukin (IL)-1β, and IL-18) were measured in peripheral blood mononuclear cells (PBMCs), macrophages, and liver using flow cytometry, quantitative real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry. The LPS was used to evaluate changes in NLRP3 and its related cytokines in CD14⁺ monocytes which may reflect immune status. Cytokine expression was measured using RT-PCR.

RESULTS

Patients with HBV-ACLF had lower NLRP3 inflammasome expression in peripheral CD14⁺ monocytes, particularly in the middle-to-late stage, but higher expression in liver macrophages compared to CHB and HCs. Compared with H-LPS or L-LPS alone, L-LPS sequential H-LPS can significantly inhibit the expression of NLRP3 and its related cytokines.

CONCLUSION

Differential expression patterns of the NLRP3 inflammasome in the periphery and liver might be related to immune dysfunction and recruitment of monocytes to the injured liver during disease progression. Persistent systemic inflammation is likely a cause of compromised immune status in patients with HBV-ACLF.

Multispectral Imaging Enables Characterization of Intrahepatic Macrophages in Patients With Chronic Liver Disease

Intrahepatic macrophages influence the composition of the microenvironment, host immune response to liver injury, and development of fibrosis. Compared with stellate cells, the role of macrophages in the development of fibrosis remains unclear. Multispectral imaging allows detection of multiple markers in situ in human formalin‐fixed, paraffin‐embedded tissue. This cutting‐edge technology is ideal for analyzing human liver tissues, as it allows spectral unmixing of fluorophore signals, subtraction of auto‐fluorescence, and preservation of hepatic architecture. We analyzed five different antibodies commonly observed on macrophage populations (CD68, MAC387, CD163, CD14, and CD16). After optimization of the monoplex stains and development of a Spectral Library, we combined all of the antibodies into a multiplex protocol and used them to stain biopsies collected from representative patients with chronic liver diseases, including chronic hepatitis C, nonalcoholic steatohepatitis, and autoimmune hepatitis. Various imaging modalities were tested, including cell phenotyping, tissue segmentation, t‐distributed stochastic neighbor embedding plots, and phenotype matrices that facilitated comparison and visualization of the identified macrophage and other cellular profiles. We then tested the feasibility of this platform to analyze numerous regions of interest from liver biopsies with multiple patients per group, using batch analysis algorithms. Five populations showed significant differences between patients positive for hepatitis C virus with advanced fibrosis when compared with controls. Three of these were significantly increased in patients with advanced fibrosis when compared to controls, and these included CD163+CD16+, CD68+, and CD68+MAC387+. Conclusion: Spectral imaging microscopy is a powerful tool that enables in situ analysis of macrophages and other cells in human liver biopsies and may lead to more personalized therapeutic approaches in the future.

The Generation and Identity of Human Myeloid-Derived Suppressor Cells

Myeloid-derived suppressor cells (MDSCs) are cells of myeloid lineage with a potent immunosuppressive capacity. They are present in cancer patients as well as in patients with severe inflammatory conditions and infections. MDSCs exist as two main subtypes, the granulocytic (G-MDSCs) and the monocytic (Mo-MDSCs) type, as defined by their surface phenotype and functions. While the functions of MDSCs have been investigated in depth, the origin of human MDSCs is less characterized and even controversial. In this review, we recapitulate theories on how MDSCs are generated in mice, and whether this knowledge is translatable into human MDSC biology, as well as on problems of defining MDSCs by their immature cell surface phenotype in relation to the plasticity of myeloid cells. Finally, the challenge of pharmacological targeting of MDSCs in the future is envisioned.

Therapeutic Targeting of Hepatic Macrophages for the Treatment of Liver Diseases

Hepatic macrophages play a central role in maintaining homeostasis in the liver, as well as in the initiation and progression of liver diseases. Hepatic macrophages are mainly derived from resident hepatic macrophages called Kupffer cells or circulating bone marrow-derived monocytes. Kupffer cells are self-renewing and typically non-migrating macrophages in the liver and are stationed in the liver sinusoids in contrast to macrophages originating from circulating monocytes. Kupffer cells regulate liver homeostasis by mediating immunity against non-pathogenic blood-borne molecules, while participating in coordinated immune responses leading to pathogen clearance, leukocyte recruitment and antigen presentation to lymphocytes present in the vasculature. Monocyte-derived macrophages infiltrate into the liver tissue when metabolic or toxic damage instigates and are likely dispensable for replenishing the macrophage population in homeostasis. In recent years, different populations of hepatic macrophages have been identified with distinct phenotypes with discrete functions, far beyond the central dogma of M1 and M2 macrophages. Hepatic macrophages play a central role in the pathogenesis of acute and chronic liver failure, liver fibrosis, non-alcoholic fatty liver disease, alcoholic liver disease, viral hepatitis, and hepatocellular carcinoma, as well as in disease resolution. The understanding of the role of hepatic macrophages in liver diseases provides opportunities for the development of targeted therapeutics for respective malignancies. This review will summarize the current knowledge of the hepatic macrophages, their origin, functions, their critical role in maintaining homeostasis and in the progression or resolution of liver diseases. Furthermore, we will provide a comprehensive overview of the therapeutic targeting strategies against hepatic macrophages developed for the treatment of liver diseases.

Sulforaphane Protects Cells against Lipopolysaccharide-Stimulated Inflammation in Murine Macrophages

Inflammation is an essential part for the general or innate immune defenses to defend against tissue damage and accelerate the curing process by providing protection against pathogens. Sulforaphane (SFN) is a natural isothiocyanate that has potential properties against inflammation, along with other protective functions. The purpose of this study was to examine the mechanism of its protective effect on lipopolysaccharide (LPS)-induced inflammation in Raw 264.7 macrophages. Here, we compared LPS-challenged macrophages with or without SFN pretreatment. Macrophages were pre-incubated for 6 h with a wide range of concentrations of SFN (0 to 50 µM), and then treated with LPS for 24 h. Nitric oxide (NO) concentration and gene expression of different inflammatory mediators, i.e., interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β, were measured. SFN neither directly reacted with cytokines, nor with NO. To understand the mechanisms, we performed analyses of the expression of regulatory enzyme inducible nitic oxide synthase (iNOS), the transcription factor NF-E2-related factor 2 (Nrf2), and its enzyme heme-oxygenase (HO)-1. Our results revealed that LPS increased significantly the expression of inflammatory cytokines and concentration of NO in non-treated cells. SFN was able to prevent the expression of NO and cytokines through regulating inflammatory enzyme iNOS and activation of Nrf2/HO-1 signal transduction pathway.

Crosstalk network among multiple inflammatory mediators in liver fibrosis

Liver fibrosis is the common pathological basis of all chronic liver diseases, and is the necessary stage for the progression of chronic liver disease to cirrhosis. As one of pathogenic factors, inflammation plays a predominant role in liver fibrosis via communication and interaction between inflammatory cells, cytokines, and the related signaling pathways. Damaged hepatocytes induce an increase in pro-inflammatory factors, thereby inducing the development of inflammation. In addition, it has been reported that inflammatory response related signaling pathway is the main signal transduction pathway for the development of liver fibrosis. The crosstalk regulatory network leads to hepatic stellate cell activation and proinflammatory cytokine production, which in turn initiate the fibrotic response. Compared with the past, the research on the pathogenesis of liver fibrosis has been greatly developed. However, the liver fibrosis mechanism is complex and many pathways involved need to be further studied. This review mainly focuses on the crosstalk regulatory network among inflammatory cells, cytokines, and the related signaling pathways in the pathogenesis of chronic inflammatory liver diseases. Moreover, we also summarize the recent studies on the mechanisms underlying liver fibrosis and clinical efforts on the targeted therapies against the fibrotic response.

A Benzenediamine Analog FC-99 Drives M2 Macrophage Polarization and Alleviates Lipopolysaccharide- (LPS-) Induced Liver Injury

Macrophages have variable functional phenotypes, high diversity, and plasticity and are involved in the pathogenesis of sepsis-induced liver injury. Alteration of macrophage polarization through activated (M1) macrophage to alternatively activated (M2) macrophage has emerged as a potential therapeutic strategy. This study was designed to explore the effect of a benzenediamine analog FC-99 on macrophage polarization in vitro and lipopolysaccharide- (LPS-) induced liver injury followed by the underlying mechanisms. For in vitro experiments, FC-99 inhibited M1-related macrophage factors and promoted M2-related markers induced by IL-4 in the mouse macrophage cell line RAW264.7. Moreover, FC-99-induced macrophages polarized to M2 phenotype which could be repressed by a PPAR-γ inhibitor but not STAT6 siRNA knockdown, indicating FC-99-induced M2 macrophage polarization through PPAR-γ rather than STAT6 signal. In LPS-induced septic mice, FC-99 pretreated mice displayed lower expression of M1 markers together with the increased M2 marker CD206 and improvement of liver injury. These findings illustrated that FC-99 could promote M2 macrophage polarization via PPAR-γ signaling and seemed to be a potential therapeutic candidate for inflammatory liver injury.

Physiologic constraints of using exosomes in vivo as systemic delivery vehicles

Systemic delivery of exosomes meets hurdles which had not been elucidated using live molecular imaging for their biodistribution. Production and uptake of endogenous exosomes are expected to be nonspecific and specific, respectively, where external stimuli of production of exosomes and their quantitative degree of productions are not understood. Despite this lack of understanding of basic physiology of in vivo behavior of exosomes including their possible paracrine or endocrine actions, many engineering efforts are taken to develop therapeutic vehicles. Especially, the fraction of exosomes’ taking the routes of waste disposal and exerting target actions are not characterized after systemic administration. Here, we reviewed the literature about in vivo distribution and disposal/excretion of exogenous or endogenous exosomes and, from these limited resources of knowledge currently available, summarized the knowledge and the uncertainties of exosomes on physiologic standpoints. An eloquent example of the investigations to understand the roles and confounders of exosomes’ action in the brain was highlighted with emphasis on the recent discovery of brain lymphatics and hypothesis of glymphatic/lymphatic clearance pathways in diseases as well as in physiologic processes. The possibility of delivering therapeutic exosomes through the systemic circulation, across blood-brain barriers and finally to target cells such as microglia, astrocytes and/or neurons is a good testbed in which the investigators can formulate problems to solve for both understanding (science) and application (engineering).

Acute kidney injury spectrum in patients with chronic liver disease: Where do we stand?

Acute kidney injury (AKI) is a common complication of liver cirrhosis and is of the utmost clinical and prognostic relevance. Patients with cirrhosis, especially decompensated cirrhosis, are more prone to develop AKI than those without cirrhosis. The hepatorenal syndrome type of AKI (HRS–AKI), a spectrum of disorders in prerenal chronic liver disease, and acute tubular necrosis (ATN) are the two most common causes of AKI in patients with chronic liver disease and cirrhosis. Differentiating these conditions is essential due to the differences in treatment. Prerenal AKI, a more benign disorder, responds well to plasma volume expansion, while ATN requires more specific renal support and is associated with substantial mortality. HRS–AKI is a facet of these two conditions, which are characterized by a dysregulation of the immune response. Recently, there has been progress in better defining this clinical entity, and studies have begun to address optimal care. The present review synopsizes the current diagnostic criteria, pathophysiology, and treatment modalities of HRS–AKI and as well as AKI in other chronic liver diseases (non-HRS–AKI) so that early recognition of HRS–AKI and the appropriate management can be established.

Human amnion mesenchymal stem cells attenuate atherosclerosis by modulating macrophage function to reduce immune response

Mesenchymal stem cells (MSCs) show immunosuppressive activities and alleviate atherosclerosis (AS) formation in apolipoprotein E-knockout (apoE-KO) mice. Human amnion mesenchymal stem cells (hAMSCs), a particular population of mesenchymal stem cells, have been shown to have immunomodulatory abilities. The present study investigated the effects of hAMSCs treatment on early atherosclerotic plaque formation and the progression of established lesion in apoE-KO mice. In total, 36 mice were fed with a high-fat diet. Mice were subjected to hAMSCs-injection treatment simultaneously with high-fat diet (early treatment) or after 8 weeks of high-fat diet (delayed treatment). In each treatment, mice were divided into three groups: i) hAMSCs group with hAMSCs treatment; ii) PBS group injected with PBS; and iii) control group without injection. Histological results showed that the plaque area in the aortic arch of mice was significantly reduced after hAMSCs treatment in the early and delayed treatment groups. In addition, immunohistochemical analysis suggested that the accumulation of macrophages was significantly decreased after hAMSCs treatment. Similarly, the release of the pro-inflammatory cytokine tumor necrosis factor-α was also decreased, whereas the release of the anti-inflammatory cytokine interleukin-10 was increased. In addition, hAMSCs treatment suppressed the phosphorylation of p65 and inhibitor of κB-α, suggesting that NF-κB pathway was involved in the hAMSCs-mediated suppression of immune response. In conclusion, hAMSCs treatment was effective in reducing immune response, which is the one of the major causes of AS, eventually leading to a significant reduction in size of athero-sclerotic lesions.

The Protective Effect of Magnesium Lithospermate B on Hepatic Ischemia/Reperfusion via Inhibiting the Jak2/Stat3 Signaling Pathway

Acute inflammation is an important component of the pathogenesis of hepatic ischemia/reperfusion injury (HIRI). Magnesium lithospermate B (MLB) has strong neuroprotective and cardioprotective effects. The purpose of this study was to determine whether MLB had underlying protective effects against hepatic I/R injury and to reveal the potential mechanisms related to the hepatoprotective effects. In this study, we first examined the protective effect of MLB on HIRI in mice that underwent 1 h ischemia followed by 6 h reperfusion. MLB pretreatment alleviated the abnormal liver function and hepatocyte damage induced by I/R injury. We found that serum inflammatory cytokines, including IL-6, IL-1β, and TNF-α, were significantly decreased by MLB during hepatic ischemia/reperfusion (I/R) injury, suggesting that MLB may alleviate hepatic I/R injury via inhibiting inflammatory signaling pathways. Second, we investigated the protein level of p-Jak2/Jak2 and p-Stat3/Stat3 using Western blotting and found that MLB could significantly inhibit the activation of the Jak2/Stat3 signaling pathway, which was further verified by AG490 in a mouse model. Finally, the effect of MLB on the Jak2/Stat3 pathway was further assessed in an in vitro model of RAW 264.7 cells; 1 µg/ml LPS induced the secretion of inflammatory mediators, including IL-6, TNF-α, and activation of the Jak2/Stat3 signaling pathway. MLB significantly inhibited the abnormal secretion of inflammatory factors and the activation of the Jak2/Stat3 signaling pathway in RAW264.7 cells. In conclusion, MLB was found for the first time to reduce inflammation induced by hepatic I/R via suppressing the Jak2/Stat3 pathway.