HMGB1 is a Central Driver of Dynamic Pro-inflammatory Networks in Pediatric Acute Liver Failure induced by Acetaminophen. Sci Rep. 2019;9:5971. [PMID: 30979951 PMCID: PMC6461628 DOI: 10.1038/s41598-019-42564-5]

Alleviation of acetaminophen-induced liver failure using silibinin nanoliposomes: An in vivo study

BACKGROUND

Acetaminophen (Act) overdose is a known inducer of liver failure in both children and adults. Cell annihilation ensues following acetaminophen overdose and its toxic metabolites by depleting cellular GSH storage and increasing ROS levels. Silymarin extract and its major compound silibinin (SLB) possess robust antioxidant properties by inducing ROS elimination; however, low bioavailability and rapid metabolism limit their applications. Herein, we aimed at using SLB liposomes to combat acetaminophen-induced acute liver toxicity.

METHODS

We have developed a SLB-lipid complex to improve SLB loading efficiency within nanoliposome by using the lipid film method. Liposomes were characterized by using DLS and TEM analysis, and the release pattern, and toxicity profile on the normal cells as well as histopathological and serum analysis were investigated to reveal relevant enzyme activities in an animal model.

RESULTS

Data demonstrated that negatively-charged SLB liposomes of 115 nm had homogeneous spherical morphology, and entrapped a considerable quantity of SLB of almost 40%. Liposomes shows a favorable release pattern and were not toxic against NIH3T3 mouse fibroblast cells. The animal study revealed that treatment of mice with SLB nanoliposomes could significantly preserve liver function as revealed by the reduced levels of ALT and AST hepatic enzymes as well as ALP in the serum. Our data indicated that intraperitoneal administration of SLB Lip could significantly reduce ALT enzyme levels (p < 0.05) compared to N-acetylcysteine, while i.v administration resulted in no significant difference compared to control animals with no treatment.

CONCLUSION

The results of this study support the significant hepatoprotective effect of SLB nanoliposomes against acetaminophen-induced toxicity depending on the route of administration.

Spotlight on liver macrophages for halting liver disease progression and injury

INTRODUCTION

Over the past two decades, understanding of hepatic macrophage biology has provided astounding details of their role in the progression and regression of liver diseases. The hepatic macrophages constitute resident macrophages, Kupffer cells, and circulating bone marrow monocyte-derived macrophages, which play a diverse role in liver injury and repair. Imbalance in the macrophage population leads to pathological consequences and is responsible for the initiation and progression of acute and chronic liver injuries. Further, distinct populations of hepatic macrophages and their high heterogeneity make their complex role enigmatic. The unique features of distinct phenotypes of macrophages have provided novel biomarkers for defining the stages of liver diseases. The distinct mechanisms of hepatic macrophages polarization and recruitment have been at the fore front of research. In addition, the secretome of hepatic macrophages and their immune regulation has provided clinically relevant therapeutic targets.

AREAS COVERED

Herein we have highlighted the current understanding in the area of hepatic macrophages, and their role in the progression of liver injury.

EXPERT OPINION

It is essential to ascertain the physiological and pathological role of evolutionarily conserved distinct macrophage phenotypes in different liver diseases before viable approaches may see a clinical translation.

Novel luteolin@pro-phytomicelles: In vitro characterization and in vivo evaluation of protection against drug-induced hepatotoxicity

A novel nanoformulation with the small molecule phytochemical dipotassium glycyrrhizinate as a nanomaterial was developed for the oral delivery of luteolin (Lut), a widely used phytochemical, but it suffered from poor water solubility and low oral bioavailability. This novel nanoformulation, named Lut@pro-phytomicelles, can be fabricated with a simple process. Lut@pro-phytomicelles can instantly dissolve into aqueous mediums and formulate through self-assembly a clear phytomicelle solution with a Lut encapsulation efficiency of 99.16 ± 0.90%, a small micelle size of 30.32 ± 0.12 nm, and a narrow polydispersity index of 0.138 ± 0.024. The optimized formulation demonstrated that Lut had solubility in up to 50 mg/ml of water as a result of its encapsulation within DG phytomicelles. Lut@pro-phytomicelles exhibited excellent characteristics, including good storage stability, a fast in vitro release profile, improvement in in vitro antioxidant activity, and high safety potential. In the oral bioavailability evaluation, a shorter Tmax, increased Cmax, and improved AUC0-t were obtained with Lut@pro-phytomicelles when compared to bare Lut. The distribution evaluation further showed that Lut@pro-phytomicelles could effectively increase the concentrations of Lut in all the tested organs and gastrointestinal segments. In the protection efficacy evaluation, 100 mg/kg Lut@pro-phytomicelles demonstrated strong effects against acetaminophen-induced hepatotoxicity. The mechanisms of inhibiting high-mobility group box 1 signaling and suppressing oxidative stress were involved in this strong treatment effect. These results showed that simple but novel Lut@pro-phytomicelles provided a new, promising nano-delivery system for Lut with a significantly improved in vivo profile.

An Update on Pediatric Acute Liver Failure: Emerging Understanding of the Impact of Immune Dysregulation and Novel Opportunities for Intervention

Pediatric acute liver failure (PALF) is a complex, unpredictable, often rapidly progressive, potentially devastating clinical syndrome that occurs in infants, children, and adolescents without pre-existing liver disease. PALF is characterized by acute onset of hepatocellular injury and liver-based coagulopathy, frequently accompanied by hepatic encephalopathy. Etiologies include drug and toxin exposures, metabolic and genetic disorders, infections, and immune-mediated disease. PALF management primarily involves early contact with and consideration of transfer to a pediatric liver transplant center and intensive supportive multidisciplinary clinical care, with targeted therapies available for a subset of causes. Outcomes include survival with native liver, death, and liver transplantation. Efforts to develop reliable clinical prognostic tools to predict PALF outcomes early in the course of disease have not yet been fulfilled, and the possibility remains that some transplanted PALF patients might have survived without transplantation.

Perfluorooctane sulfonate aggravates CCl4-induced hepatic fibrosis via HMGB1/TLR4/Smad signaling

Perfluorooctane sulfonate (PFOS) is a widespread environmental pollutant and may cause a variety of adverse health effects. The hepatotoxicity of PFOS has attracted particular attention, given the fact that the liver has one of the highest PFOS accumulations among human tissues. In this study, we revealed that subchronic PFOS exposure may exacerbate carbon tetrachloride (CCl₄ )-induced liver fibrosis in animal models. Administration with 1 mg/kg PFOS every other day for 56 days dramatically enhanced CCl₄ -mediated liver injury and hepatic stellate cell (HSC) activation. Furthermore, PFOS exposure may promote the activation of high-mobility group box 1 (HMGB1)/toll-like receptor 4 (TLR4) signaling pathway through inducing the secretion of HMGB1 from hepatocytes. PFOS exposure induced the translocation of HMGB1 from the nucleus into the cytoplasm of hepatocytes and cultured BRL-3A cells at a starting concentration of 50 μM. This process is accompanied with concurrent flux of calcium, suggesting a link between calcium signaling and HMGB1 release following PFOS exposure. Finally, we showed that PFOS-exposed conditional medium (PFOS-CM) of hepatocytes may induce the translocation of Smad2/3 in HSCs in a TLR4-dependent manner. Taken together, subchronic PFOS exposure might play a pro-fibrotic role via a HMGB1/TLR4-dependent Smad signaling in HSCs. Our findings for the first time uncovered an involvement of PFOS exposure in liver fibrosis via HMGB1/TLR4/Smad signaling.

HMGB1: An overview of its roles in the pathogenesis of liver disease

High-mobility group box 1 (HMGB1) is an abundant architectural chromosomal protein that has multiple biologic functions: gene transcription, DNA replication, DNA-damage repair, and cell signaling for inflammation. HMGB1 can be released passively by necrotic cells or secreted actively by activated immune cells into the extracellular milieu after injury. Extracellular HMGB1 acts as a damage-associated molecular pattern to initiate the innate inflammatory response to infection and injury by communicating with neighboring cells through binding to specific cell-surface receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation end products (RAGE). Numerous studies have suggested HMGB1 to act as a key protein mediating the pathogenesis of chronic and acute liver diseases, including nonalcoholic fatty liver disease, hepatocellular carcinoma, and hepatic ischemia/reperfusion injury. Here, we provide a detailed review that focuses on the role of HMGB1 and HMGB1-mediated inflammatory signaling pathways in the pathogenesis of liver diseases.

Dynamics of Systemic Inflammation as a Function of Developmental Stage in Pediatric Acute Liver Failure

The Pediatric Acute Liver Failure (PALF) study is a multicenter, observational cohort study of infants and children diagnosed with this complex clinical syndrome. Outcomes in PALF reflect interactions among the child’s clinical condition, response to supportive care, disease severity, potential for recovery, and, if needed, availability of a suitable organ for liver transplantation (LTx). Previously, we used computational analyses of immune/inflammatory mediators that identified three distinct dynamic network patterns of systemic inflammation in PALF associated with spontaneous survivors, non-survivors (NS), and LTx recipients. To date, there are no data exploring age-specific immune/inflammatory responses in PALF. Accordingly, we measured a number of clinical characteristics and PALF-associated systemic inflammatory mediators in daily serum samples collected over the first 7 days following enrollment from five distinct PALF cohorts (all spontaneous survivors without LTx): infants (INF, <1 year), toddlers (TOD, 1–2 years.), young children (YCH, 2–4 years), older children (OCH, 4–13 years) and adolescents (ADO, 13–18 years). Among those groups, we observed significant (P<0.05) differences in ALT, creatinine, Eotaxin, IFN-γ, IL-1RA, IL-1β, IL-2, sIL-2Rα, IL-4, IL-6, IL-12p40, IL-12p70, IL-13, IL-15, MCP-1, MIP-1α, MIP-1β, TNF-α, and NO2−/NO3−. Dynamic Bayesian Network inference identified a common network motif with HMGB1 as a central node in all sub-groups, with MIG/CXCL9 being a central node in all groups except INF. Dynamic Network Analysis (DyNA) inferred different dynamic patterns and overall dynamic inflammatory network complexity as follows: OCH>INF>TOD>ADO>YCH. Hypothesizing that systemically elevated but sparsely connected inflammatory mediators represent pathological inflammation, we calculated the AuCon score (area under the curve derived from multiple measures over time divided by DyNA connectivity) for each mediator, and identified HMGB1, MIG, IP-10/CXCl10, sIL-2Rα, and MCP-1/CCL2 as potential correlates of PALF pathophysiology, largely in agreement with the results of Partial Least Squares Discriminant Analysis. Since NS were in the INF age group, we compared NS to INF and found greater inflammatory coordination and dynamic network connectivity in NS vs. INF. HMGB1 was the sole central node in both INF and NS, though NS had more downstream nodes. Thus, multiple machine learning approaches were used to gain both basic and potentially translational insights into a complex inflammatory disease.

Increased risk of acute liver failure by pain killer drugs in NAFLD: Focus on nuclear receptors and their coactivators

Non-alcoholic fatty liver disease (NAFLD) is a global condition characterized by an accumulation of lipids in the hepatocytes. NAFLD ranges from simple steatosis, a reversible and relatively benign condition, to fibrosis with non-alcoholic steatohepatitis (NASH), potentially leading to cirrhosis and hepatocarcinoma. NAFLD can increase the susceptibility to severe liver injury with eventual acute liver failure induced by specific hepatotoxic drugs, including acetaminophen (APAP), which is commonly used as analgesic and antipyretic. Although several animal models have been used to clarify the predisposing role of hepatic steatosis to APAP intoxication, the exact mechanism is still not clear. Here, we shed a light into the association between NAFLD and APAP toxicity by examining the peculiar role of nuclear receptor peroxisome proliferator-activated receptor α (PPARα) and coactivator peroxisome proliferator-activated receptor gamma coactivator 1-β (PGC-1β) in driving fatty acid metabolism, inflammation and mitochondria redox balance. The knowledge of the mechanism that exposes patients with NAFLD to higher risk of acute liver failure by pain killer drug is the first step to eventually claim for a reduction of the maximal diurnal dose of APAP for subjects with liver steatosis.

Evaluation of the Biomarkers HMGB1 and IL-6 as Predictors of Mortality in Cirrhotic Patients with Acute Kidney Injury

Background

Acute kidney injury (AKI) affects from 20% to 50% of cirrhotic patients, and the one-month mortality rate is 60%. The main cause of AKI is bacterial infection, which worsens circulatory dysfunction through the release of HMGB1 and IL-6.

Objectives

To evaluate HMGB1 and IL-6 as biomarkers of morbidity/mortality.

Methods

Prospective, observational study of 25 hospitalised cirrhotic patients with AKI. Clinical and laboratory data were collected at the time of diagnosis of AKI, including serum HMGB1 and IL-6.

Results

The mean age was 55 years; 70% were male. Infections accounted for 13 cases. The 30-day and three-month mortality rates were 17.4% and 30.4%, respectively. HMGB1 levels were lower in survivors than in nonsurvivors at 30 days (1174.2 pg/mL versus 3338.5 pg/mL, p = 0.035), but not at three months (1540 pg/mL versus 2352 pg/mL, p = 0.243). Serum IL-6 levels were 43.3 pg/mL versus 153.3 pg/mL (p = 0.061) at 30 days and 35.8 pg/mL versus 87.9 pg/mL (p = 0.071) at three months, respectively. The area under the ROC curve for HMGB1 was 0.842 and 0.657, and that for IL-6 was 0.803 and 0.743 for discriminating nonsurvivors at 30 days and three months, respectively. In multivariate analysis, no biomarker was independently associated with mortality.

Conclusion

HMGB1 levels were associated with decreased survival in cirrhotics. Larger studies are needed to confirm our results.

Role of High-Mobility Group Box-1 in Liver Pathogenesis

High-mobility group box 1 (HMGB1) is a highly abundant DNA-binding protein that can relocate to the cytosol or undergo extracellular release during cellular stress or death. HMGB1 has a functional versatility depending on its cellular location. While intracellular HMGB1 is important for DNA structure maintenance, gene expression, and autophagy induction, extracellular HMGB1 acts as a damage-associated molecular pattern (DAMP) molecule to alert the host of damage by triggering immune responses. The biological function of HMGB1 is mediated by multiple receptors, including the receptor for advanced glycation end products (RAGE) and Toll-like receptors (TLRs), which are expressed in different hepatic cells. Activation of HMGB1 and downstream signaling pathways are contributing factors in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), and drug-induced liver injury (DILI), each of which involves sterile inflammation, liver fibrosis, ductular reaction, and hepatic tumorigenesis. In this review, we will discuss the critical role of HMGB1 in these pathogenic contexts and propose HMGB1 as a bona fide and targetable DAMP in the setting of common liver diseases.

High mobility group box-1 release from H2O2-injured hepatocytes due to sirt1 functional inhibition

BACKGROUND

High mobility group box-1 (HMGB1), recognized as a representative of damage-associated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited.

AIM

To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress.

METHODS

C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H₂O₂ were used to establish an in vitro model. Serum alanine aminotransferase, liver H₂O₂ content and catalase activity, lactate dehydrogenase and 8-hydroxy-2-deoxyguanosine content, nicotinamide adenine dinucleotide (NAD⁺) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation.

RESULTS

When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H₂O₂ could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD⁺-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD⁺ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation.

CONCLUSION

The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.