Involvement of tumor necrosis factor-alpha in development of hepatic injury in galactosamine-sensitized mice

The Experience of Using Multipotent Mesenchymal Stromal Cells in the Treatment of Severe Recurrent Cholangitis in Children with Biliary Atresia after Kasai Surgery

This article describes the experience of application of multipotent mesenchymal stromal cells in the complex therapy of severe recurrent cholangitis in 2 children with biliary atresia after Kasai surgery. In both children, hepatic cellular insufficiency and portal hypertension developed against the background of long-term inflammatory process poorly controlled by standard therapy, which was the indication for liver transplantation. During the course of mesenchymal stromal cells therapy, the relief of the inflammatory process and functional recovery of the liver were achieved. At the time of preparing the article, the follow-up of two children since the start of multipotent mesenchymal stromal cell therapy was 3 years 9 months and 2 years 6 months. No recurrence of cholangitis was observed in the patients during the follow-up period, the liver function was preserved. There are no indications for liver transplantation at this moment. Thus, despite the fact that the mechanisms of therapeutic action of multipotent mesenchymal stromal cells in biliary atresia require further investigation, we obtained promising results suggesting the possibility of using mesenchymal stromal cells in the treatment of postoperative complications in children with biliary atresia.

Hepatoprotective Effects of Albumin-Encapsulated Nanoparticles of a Curcumin Derivative COP-22 against Lipopolysaccharide/D-Galactosamine-Induced Acute Liver Injury in Mice

Acute liver injury (ALI) is a severe syndrome and can further develop into acute liver failure (ALF) which can lead to high mortality and cause irreversible liver injuries in the clinic. Liver transplantation is the most common treatment; however, liver donors are lacking, and the progression of ALF is rapid. Nanoparticles can increase the bioavailability and the targeted accumulation of drugs in the liver, so as to significantly improve the therapeutic effect of ALI. Curcumin derivative COP-22 exhibits low cytotoxicity and effective anti-inflammatory activity; however, it has poor water solubility. In this study, COP-22-loaded bovine serum albumin (BSA) nanoparticles (22 NPs) were prepared and characterized. They exhibit effective hepatoprotective effects by inhibiting inflammation, oxidative stress, and apoptosis on Lipopolysaccharide/D-Galactosamine-induced acute liver injury of mice. The anti-inflammatory activity of 22 NPs is related to the regulation of the NF-κB signaling pathways; the antioxidant activity is related to the regulation of the Nrf2 signaling pathways; and the apoptosis activity is related to mitochondrial pathways, involving Bcl-2 family and Caspase-3 protein. These three cellular pathways are interrelated and affected each other. Moreover, 22 NPs could be passively targeted to accumulate in the liver through the retention effect and are more easily absorbed than 22.HCl salt in the liver.

A narrative review of liver regeneration-from models to molecular basis

Objective

To elucidate the characteristics of different liver regeneration animal models, understand the activation signals and mechanisms related to liver regeneration, and obtain a more comprehensive conception of the entire liver regeneration process.

Background

Liver regeneration is one of the most enigmatic and fascinating phenomena of the human organism. Despite suffering significant injuries, the liver still can continue to perform its complex functions through the regeneration system. Although advanced topics on liver regeneration have been proposed; unfortunately, complete regeneration of the liver has not been achieved until now. Therefore, increasing understanding of the liver regenerative process can help improve our treatment of liver failure. It will provide a new sight for the treatment of patients with liver injury in the clinic.

Methods

Literatures on liver regeneration animal models and involved basic research on molecular mechanisms were retrieved to analyze the characteristics of different models and those related to molecular basis.

Conclusions

The process of liver regeneration is complex and intricate, consisting of various and interactive pathways. There is sufficient evidence to demonstrate that liver regeneration is similar between humans and rodents. At the same time, many of the same cytokines, growth factors, and signaling pathways are relevant. There are many gaps in our current knowledge. Understanding of this knowledge will provide more supportive clinical treatment strategies, including small-scale liver transplantation and high-quality regenerative process after surgical resection, and offer possible targets to treat the dysregulation of regeneration that occurs in chronic hepatic diseases and tumors. Current research work, such as the use of animal models as in vivo vectors for high-quality human hepatocytes, represents a unique and significant cutting edge in the field of liver regeneration.

Actions and Therapeutic Potential of Madecassoside and Other Major Constituents of Centella asiatica: A Review

Centella asiatica is a popular herb well-known for its wide range of therapeutic effects and its use as a folk medicine for many years. Its therapeutic properties have been well correlated with the presence of asiaticoside, madecassoside, asiatic and madecassic acids, the pentacyclic triterpenes. The herb has been extensively known to treat skin conditions; nevertheless, several pre-clinical and clinical studies have scientifically demonstrated its effectiveness in other disorders. Among the active constituents that have been identified in Centella asiatica, madecassoside has been the subject of only a relatively small number of scientific reports. Therefore, this review, while including other major constituents of this plant, focuses on the therapeutic potential, pharmacokinetics and toxicity of madecassoside.

Susceptibility of Asialoglycoprotein Receptor-Deficient Mice to Lps/Galactosamine Liver Injury and Protection by Betaine Administration

BACKGROUND

Work from our laboratory has shown that the ethanol-induced increase in apoptotic hepatocellular death is closely related to the impairment in the ability of the asialoglycoprotein receptor (ASGP-R) to remove neighboring apoptotic cells. In this study, we assessed the role of ASGP-R in fulminant liver failure and investigated whether prior treatment with betaine (a naturally occurring tertiary amine) is protective.

METHODS

Lipopolysaccharide (LPS; 50 μg/kg BW) and galactosamine (GalN; 350 mg/kg BW) were injected together to wild-type and ASGP-R-deficient mice that were treated for two weeks prior with or without 2% betaine in drinking water. The mice were sacrificed 1.5, 3, or 4.5 h post-injection, and tissue samples were collected.

RESULTS

LPS/GalN injection generate distinct molecular processes, which includes increased production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), thus causing apoptosis as evident by increased caspase-3 activity. ASGP-R deficient animals showed increased liver caspase activities, serum TNF-α and IL-6 levels, as well as more pronounced liver damage compared with the wild-type control animals after intraperitoneal injection of LPS/GalN. In addition, prior administration of betaine was found to significantly attenuate the LPS/GalN-induced increases in liver injury parameters.

CONCLUSION

Our work underscores the importance of normal functioning of ASGP-R in preventing severe liver damage and signifies a therapeutic role of betaine in prevention of liver injuries from toxin-induced fulminant liver failure.

Kaempferol protects mice from d-GalN/LPS-induced acute liver failure by regulating the ER stress-Grp78-CHOP signaling pathway

Kaempferol is a flavonoid compound that has many functions, such as anti-inflammation and antioxidation. Acute liver failure (ALF) is a life-threatening illness accompanied by serious inflammation and extensive hepatocyte apoptosis. The aim of this study was to examine the therapeutic potential of kaempferol and its mechanism in ALF. In a murine ALF model induced by d-galactosamine (d-GalN, 700 mg/kg) / lipopolysaccharide (LPS, 10 μg/kg), mice were pretreated with kaempferol at 2 h before d-GalN/LPS administration and then sacrificed 6 h after d-GalN/LPS injection. Lethality, liver damage, endoplasmic reticulum(ER) stress, hepatocyte viability and apoptosis were evaluated. Whether pretreatment of kaempferol protected hepatocytes from ER stress-induced apoptosis was detected in vitro. Pretreatment of kaempferol decreased lethality, prolonged the survival time and significantly protected against liver injury, which was indicated by decreased transaminase levels and the well-preserved liver structure. The protective effect of kaempferol on the ALF mouse model was achieved by inhibiting hepatocyte apoptosis. Moreover, pretreatment of kaempferol increased the expression of glucose-regulated/binding immunoglobulin protein 78 (Grp78), decreased the expression of C/EBP-homologous protein (CHOP), and protected hepatocytes from ER stress-induced apoptosis in vitro. Our results showed that pretreatment of Grp78 siRNA partially negated the hepatic protection from kaempferol and reversed the inhibition of CHOP protein expression in d-GalN/LPS-induced ALF mice. In conclusion, kaempferol inhibits hepatocyte apoptosis to protect mice from liver failure by regulating the ER stress-Grp78-CHOP signaling pathway. Therefore, kaempferol may be used to treat ALF.

Madecassoside prevents acute liver failure in LPS/D-GalN-induced mice by inhibiting p38/NF-κB and activating Nrf2/HO-1 signaling

Madecassoside (MA), a triterpenoid saponin isolated from Centella asiatica, exerts various pharmacological activities including antioxidative and anti-inflammatory effects. The aim of this study was to explore the protective effect of MA in the treatment of lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced acute liver failure(ALF) in mice. We hypothesized that MA administration may decrease the degree of liver injury caused by LPS/D-GalN. In this study, we investigated this hypothesis by treating a mouse model of LPS/D-GalN-induced liver injury with MA. Our study demonstrated that MA (20 mg/kg and 40 mg/kg) treatment for 10 days attenuated LPS/D-GalN-induced liver injury by protecting liver function, suppressing the production of inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, and recovering antioxidant enzyme activity. MA also significantly suppressed LPS-stimulated protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 by blocking the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and eukaryotic transcription factor nuclear factor-kappa B (NF-κB). In addition, MA treatment enhanced protein levels of heme oxygenase (HO)-1 and anti-oxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) through the upregulation of nuclear factor E2-related factor 2 (Nrf2) in LPS-stimulated liver injury. These results suggest that MA is a promising agent for the treatment of LPS/D-GalN-induced liver injury that could serve as a candidate for the development of a hepatoprotective drug against ALF.

A systems pharmacology-oriented discovery of a new therapeutic use of the TCM formula Liuweiwuling for liver failure

Multiple components of traditional Chinese medicine (TCM) formulae determine their treatment targets for multiple diseases as opposed to a particular disease. However, discovering the unexplored therapeutic potential of a TCM formula remains challenging and costly. Inspired by the drug repositioning methodology, we propose an integrated strategy to feasibly identify new therapeutic uses for a formula composed of six herbs, Liuweiwuling. First, we developed a comprehensive systems approach to enrich drug compound-liver disease networks to analyse the major predicted diseases of Liuweiwuling and discover its potential effect on liver failure. The underlying mechanisms were subsequently predicted to mainly attribute to a blockade of hepatocyte apoptosis via a synergistic combination of multiple effects. Next, a classical pharmacology experiment was designed to validate the effects of Liuweiwuling on different models of fulminant liver failure induced by D-galactosamine/lipopolysaccharide (GalN/LPS) or thioacetamide (TAA). The results indicated that pretreatment with Liuweiwuling restored liver function and reduced lethality induced by GalN/LPS or TAA in a dose-dependent manner, which was partially attributable to the abrogation of hepatocyte apoptosis by multiple synergistic effects. In summary, the integrated strategy discussed in this paper may provide a new approach for the more efficient discovery of new therapeutic uses for TCM formulae.

Hepatic Immune System: Adaptations to Alcohol

Both the innate and adaptive immune systems are critical for the maintenance of healthy liver function. Immune activity maintains the tolerogenic capacity of the liver, modulates hepatocellular response to various stresses, and orchestrates appropriate cellular repair and turnover. However, in response to heavy, chronic alcohol exposure, the finely tuned balance of pro- and anti-inflammatory functions in the liver is disrupted, leading to a state of chronic inflammation in the liver. Over time, this non-resolving inflammatory response contributes to the progression of alcoholic liver disease (ALD). Here we review the contributions of the cellular components of the immune system to the progression of ALD, as well as the pathophysiological roles for soluble and circulating mediators of immunity, including cytokines, chemokines, complement, and extracellular vesicles, in ALD. Finally, we compare the role of the innate immune response in health and disease in the liver to our growing understanding of the role of neuroimmunity in the development and maintenance of a healthy central nervous system, as well as the progression of neuroinflammation.

Qingchangligan formula attenuates the inflammatory response to protect the liver from acute failure induced by d-galactosamine/lipopolysaccharide in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The Qingchangligan formula, a traditional Chinese medicine comprising five herbs, is useful for treatment of patients with liver failure; however, its protective and regulatory mechanisms remain elusive.

AIM OF THE STUDY

To test the hypothesis that the Qingchangligan formula protects mice against acute liver failure by inhibiting liver inflammation.

MATERIALS AND METHODS

Acute liver failure (ALF) was induced by intraperitoneal injection of D-GalN (700mg/kg) plus LPS (10μg/kg). The Qingchangligan formula was administered to mice in three doses of 50mg/kg (on day 1, day 2, and day 3) prior to D-GalN/LPS injection by intragastric administration. The mice in different groups were sacrificed at 6h after D-GalN/LPS injection, and liver samples and blood were collected for analysis.

RESULTS

Administration of the Qingchangligan formula not only ameliorated liver injury, as evidenced by reduced transaminase levels and well-preserved liver architecture, but also decreased the lethality in ALF mice. Moreover, in the ALF model, pretreatment with the Qingchangligan formula alleviated liver inflammation and decreased hepatocyte apoptosis. Further demonstrating the protective effects of the Qingchangligan formula, we found that pretreatment with the Qingchangligan formula reduced the expression of inflammatory cytokines by decreasing the expression of components of the mitogen-activated protein kinase (MAPK) pathway and promoting autophagy in vitro and in vivo.

CONCLUSIONS

Our findings demonstrated that the Qingchangligan formula exerts a protective effect against the pathophysiology of ALF, especially in regulating liver inflammation, and provide a rationale for using the Qingchangligan formula as a potential therapeutic strategy to ameliorate ALF.

Exosomes derived from human menstrual blood-derived stem cells alleviate fulminant hepatic failure

Background

Human menstrual blood-derived stem cells (MenSCs) are a novel source of MSCs that provide the advantage of being easy to collect and isolate. Exosomes contain some mRNAs and adhesion molecules that can potentially impact cellular and animal physiology. This study aimed to investigate the therapeutic potential of MenSC-derived exosomes (MenSC-Ex) on AML12 cells (in vitro) and D-GalN/LPS-induced FHF mice (in vivo).

Methods

Transmission electron microscopy and Western blot were used to identify MenSC-Ex. Antibody array was used to examine cytokine levels on MenSC-Ex. MenSC-Ex were treated in D-GalN/LPS-induced AML12 in vitro. Cell proliferation and apoptosis were measured. MenSC-Ex were injected into the tail veins of mice 24 h before treatment with D-GalN/LPS. Blood and liver tissues served as physiological and biochemical indexes. The number of liver mononuclear cells (MNCs) and the amount of the active apoptotic protein caspase-3 were determined to elaborate the mechanism of hepatoprotective activity.

Results

Human menstrual blood-derived stem cell-derived exosomes (MenSC-Ex) are bi-lipid membrane vesicles that have a round, ball-like shape with a diameter of approximately 30–100 nm. Cytokine arrays have shown that MenSC-Ex expressed cytokines, including ICAM-1, angiopoietin-2, Axl, angiogenin, IGFBP-6, osteoprotegerin, IL-6, and IL-8. MenSC-Ex markedly improved liver function, enhanced survival rates, and inhibited liver cell apoptosis at 6 h after transplantation. MenSC-Ex migrated to sites of injury and to AML12 cells (a mouse hepatocyte cell line), respectively. Moreover, MenSC-Ex reduced the number of liver mononuclear cells (MNCs) and the amount of the active apoptotic protein caspase-3 in injured livers.

Conclusions

In conclusion, our results provide preliminary evidence for the anti-apoptotic capacity of MenSC-Ex in FHF and suggest that MenSC-Ex may be an alternative therapeutic approach to treat FHF.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0453-6) contains supplementary material, which is available to authorized users.

Staphylococcal enterotoxin B induces hepatic injury and lethal shock in endotoxin-resistant C3H/HeJ mice despite a deficient macrophage response

Bacterial toxins, including endotoxin/LPS as well as superantigens, are major causative agents of multi-organ failure associated with sepsis and liver disease. However, the precise mechanisms initiating cell activation by the toxins have not been clarified. We compared lethal shock and cytokine production in response to LPS with responses to the superantigen staphylococcal enterotoxin B (SEB) in both LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice treated with D-galactosamine (GalN). LPS was not lethal and did not induce production of TNF-α in C3H/HeJ mice. In contrast, SEB produced lethal shock associated with liver failure and induced cytokines such as TNF-α, IFN-γ, and IL-2 in both C3H/HeN and C3H/HeJ mice. Peritoneal macrophages from C3H/HeJ mice did not produce TNF-α in vitro in response to SEB or LPS. However, no significant difference was observed in production of TNF-α in response to stimulation in vitro by SEB between C3H/HeN and C3H/HeJ splenic lymphocytes. We have demonstrated that SEB causes lethal toxicity associated with liver injury in LPS-hyporesponsive C3H/HeJ mice and that as the underlying mechanism, the normal T-cell function in these mice still maintained the sensitivity to SEB since the genetic defect of C3H/HeJ mice unresponsive to LPS and SEB is restricted in macrophages/monocytes and does not extend to T cells.

Lipopolysaccharide-induced vacuoles in macrophages: Their origin is plasma membrane-derived organelles and endoplasmic reticulum, but not lysosomes

Lipopolysaccharide (LPS) is one of the potent activators of macrophages. LPS was shown to induce cell spreading and large vacuoles in the cytoplasm of a macrophage-like cell line, JY3. These vacuoles were negative for acid phosphatase histochemistry and did not take up Lucifer yellow added to the medium. Latex beads were incorporated into cytoplasmic vesicles distinct from the vacuoles. These results indicated that the vacuoles are neither phagosomes nor lysosomes.

DiIC18(3), a specific marker of endoplasmic reticulum (ER), stained the vacuoles intensely, and DiOC6(3) stained the vacuoles at a density similar to nuclear envelope, suggesting ER origin of their membrane. Glucose-6-phosphatase, however, was not detected histochemically.

Vacuoles were also stained with wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or WGA-biotin, suggesting that the vacuoles originated from plasma membrane-endosome-trans Golgi network-secretory granule pathway. Golgi markers, TPPase or BODIPY-ceramide were not localized to the vacuolar membrane.

These results indicate that the vacuoles may have dual origins; ER and plasma membrane-derived organelles.

Hepatoprotective effects of AdipoRon against d-galactosamine-induced liver injury in mice

Adiponectin is an antidiabetic and antiatherogenic adipokine, which plays distinct roles in the balance of energy homoeostasis. As an insulin sensitizing hormone, adiponectin exerts multiple biological effects by the specific receptors (AdipoR1 and AdipoR2), through activation of AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor (PPAR)α pathways. AdipoRon, an orally active synthetic small-molecule AdipoR agonist, shows very similar effects to adiponectin in vitro and in vivo, which could be a promising therapeutic approach for obesity-related disorders. In view of the regulatory effects of adiponectin or AdipoRon on inflammatory response and energy metabolism, they might be endowed a curative potential for tissue damage. Hence, its effects and possible mechanism were investigated. In vitro studies on hepatocytes (L02) and macrophages (RAW264.7) suggested a protective and anti-inflammatory potential of AdipoRon. The effects were verified in acute hepatic injury mice induced by d-galactosamine (D-GalN): hepatic lesions were restored by AdipoRon or bicyclol (positive reference drug) pretreatment, which were characterized by a significant increase in serological and hepatic biomarkers (AST, ALT, MDA and NOSs). Besides, AdipoRon attenuated the inflammation in the liver, characterized by the dwindling proinflammatory macrophage infiltration, as well as the shrinkage of tumor necrosis factor-α (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6); meanwhile conversely promoted AMPK activation by phosphorylation. Combined with liver histopathology, these results demonstrated the hepatoprotective effects of AdipoRon against D-GalN-induced damage, which might be ascribed to the attenuation of inflammation, inhibition of free radical reactions, as well as enhancement of liver energy metabolism.

Opposing role of tumor necrosis factor receptor 1 signaling in T cell-mediated hepatitis and bacterial infection in mice

Death receptor (DR) ligands such as tumor necrosis factor (TNF) have been identified as fundamental mediators of liver damage both in mouse models and in humans. While the essential site of function of DR signaling is conceivably the hepatocyte, a systematic analysis is missing. Using mice with conditional gene ablation, we analyzed the tissue-specific function of DR signaling in T cell-dependent (concanavalin A) and independent (lipopolysaccharide/galactosamine) hepatitis and in models of bacterial infection (Listeria monocytogenes, lipopolysaccharide). We report that lipopolysaccharide/galactosamine-induced liver injury depends on hepatocyte-intrinsic TNF receptor 1 (p55, TNFR1). In contrast, we show that T cell-induced hepatitis was independent of TNFR1 signaling in hepatocytes, T cells, or endothelial cells. Moreover, T cell-induced hepatitis was independent of hepatocyte-intrinsic Fas-associated protein with death domain, TNF-related apoptosis-inducing ligand receptor, or Fas signaling. Instead, concanavalin A-induced hepatitis was completely prevented in mice with myeloid-derived cell (MDC)-specific deletion of TNFR1. Significantly, however, mice lacking TNFR1 in MDCs succumbed to listeria infection, although they displayed similar sensitivity toward endotoxin-induced septic shock when compared to control mice. These results suggest that TNFR1 signaling in MDCs is a critical mediator of both the detrimental and the protective functions of TNF in T cell-induced hepatitis and bacterial infection, respectively.

CONCLUSION

The critical site of action of DRs is completely dependent on the nature of hepatitis; the data specify MDCs as the essential cell type of TNFR1 function in T cell-mediated hepatitis and in the response to listeria, thereby identifying the opposing role of MDC TNFR1 in autoimmunity and bacterial infection. (Hepatology 2016;64:508-521).

BML-111 Protected LPS/D-GalN-Induced Acute Liver Injury in Rats

Lipoxins (LXs) display unique pro-resolving and anti-inflammatory functions in a variety of inflammatory conditions. The present study was undertaken to investigate the effects of BML-111 (5(S),6(R),7-trihydroxyheptanoic acid methyl ester), the agonist of lipoxin A₄ receptor, in a model of Lipopolysaccharides (LPS) and d-Galactosamine (d-GalN) induced acute liver injury, and to explore the mechanisms. Histopathological analyses were carried out to quantify liver injury degree. The activities of myeloperoxidase (MPO) were examined to evaluate the levels of neutrophil infiltration. The activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum were detected to evaluate the functions of the liver. The amounts of tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and interleukin-1β (IL-1β) were measured using enzyme-linked immunosorbent assay (ELISA), and the expression levels of transforming growth factor-β1(TGF-β1) and cyclooxygenase-2 (COX-2) were examined using Western blotting. The antioxidant capacity, the activities of inducible nitric oxide synthase (iNOS), the contents of malondialdehyde (MDA) and nitric oxide (NO) were analyzed with the kits via biochemical analysis. We established the model of acute liver injury with lipopolysaccharide and d-Galactosamine (LPS/d-GalN): (1) histopathological results and MPO activities, with the activities of AST and ALT in serum, consistently demonstrated LPS and d-GalN challenge could cause severe liver damage, but BML-111 could prevent pathological changes, inhibit neutrophil infiltration, and improve the hepatic function; (2) LPS/d-GalN increased TNF-α, IL-1β, COX-2, and IL-10, while decreasing TGF-β1. However, BML-111 could repress LPS/d-GalN -induced TNF-α, IL-1β and COX-2, meanwhile increasing the expression levels of TGF-β1 and IL-10; (3) LPS/d-GalN inhibited the activities of superoxide dismutase (SOD), catalase (CAT), total antioxidant capacity (T-AOC), and hydroxyl radical-scavenging ability, simultaneously increasing the levels of MDA and NO, so also the activity of iNOS. Otherwise, BML-111 could reverse all the phenomena. In a word, BML-111 played a protective role in acute liver injury induced by LPS and d-GalN in rats, through improving antioxidant capacity and regulating the balance of inflammatory cytokines.

Chlorogenic acid inhibits cholestatic liver injury induced by α-naphthylisothiocyanate: involvement of STAT3 and NFκB signalling regulation

OBJECTIVES

Chlorogenic acid (CGA) is one of the most widely consumed polyphenols in diets and is recognized to be a natural hepatoprotective agent. Here, we evaluated the protective effect and the potential mechanism of CGA against ɑ-naphthylisothiocyanate (ANIT)-induced cholestasis and liver injury.

METHODS

Twenty-five male 129/Sv mice were administered with CGA, and ANIT challenge was performed at 75 mg/kg on the 4th day. Blood was collected and subjected to biochemical analysis; the liver tissues were examined using histopathological analysis and signalling pathways.

KEY FINDINGS

Chlorogenic acid almost totally attenuated the ANIT-induced liver damage and cholestasis, compared with the ANIT group. Dose of 50 mg/kg of CGA significantly prevented ANIT-induced changes in serum levels of alanine aminotransferase, alkaline phosphatases, total bile acid, direct bilirubin, indirect bilirubin (5.3-, 6.3-, 18.8-, 158-, 41.4-fold, P<0.001) and aspartate aminotransferase (4.6-fold, P<0.01). Expressions of the altered bile acid metabolism and transport-related genes were normalized by cotreatment with CGA. The expressions of interleukin 6, tumour necrosis factor-α and suppressor of cytokine signalling 3 were found to be significantly decreased (1.2-fold, ns; 11.0-fold, P<0.01; 4.4-fold, P<0.05) in the CGA/ANIT group. Western blot revealed that CGA inhibited the activation and expression of signal transducer and activator of transcription 3 and NFκB.

CONCLUSIONS

These data suggest that CGA inhibits both ANIT-induced intrahepatic cholestasis and the liver injury. This protective effect involves down-regulation of STAT3 and NFκB signalling.

3,3'-Diindolylmethane attenuates LPS-mediated acute liver failure by regulating miRNAs to target IRAK4 and suppress Toll-like receptor signalling

BACKGROUND AND PURPOSE

Acute liver failure (ALF) is a severe and potentially lethal clinical syndrome. 3,3'-Diindolylmethane (DIM) is a natural plant-derived compound with anti-cancer activities. Recently, DIM has also been shown to have anti-inflammatory properties. Here, we tested the hypothesis that DIM would suppress endotoxin-induced ALF.

EXPERIMENTAL APPROACH

We investigated the therapeutic potential of DIM in a mouse model of D-galactosamine/Lipopolysaccharide (GalN/LPS)-induced ALF. The efficacy of DIM treatment was assessed by survival, liver histopathology, serum levels of alanine transaminase, pro-inflammatory cytokines and number of activated liver macrophages. Effects of DIM on the expression of two miRNAs, 106a and 20b, and their predicted target gene were measured by qRT-PCR and Western blotting. Effects of DIM on the release of TNF-α from RAW264.7 macrophages transfected with mimics of these miRNAs and activated by LPS was assessed by elisa.

KEY RESULTS

DIM treatment protected mice from ALF symptoms and reduced the number of activated liver macrophages. DIM increased expression of miR-106a and miR-20b in liver mononuclear cells and decreased expression of their predicted target gene IL-1 receptor-associated kinase 4 (IRAK4), involved in signalling from Toll-like receptor 4 (TLR4). In vitro transfection of RAW264.7 cells using miRNA mimics of miR-106a and 20b decreased expression of IRAK4 and of TNF-α secretion, following LPS stimulation.

CONCLUSIONS AND IMPLICATIONS

DIM attenuated GalN/LPS-induced ALF by regulating the expression of unique miRNAs that target key molecules in the TLR4 inflammatory pathway. DIM may represent a potential novel hepatoprotective agent.

Clinical and pathological features of Nerium oleander extract toxicosis in wistar rats

BACKGROUND

Nerium oleander has been widely studied for medicinal purposes for variety of maladies. N. oleander has also been reported having noxious effects because of its number of components that may show signs of toxicity by inhibiting plasma lemma Na+, K+-ATPase. The present study was performed to scrutinize the toxic effect of N. oleander leaves extract and its clinical and pathological features in wistar rats.

RESULTS

Hematological analysis showed significant variations in RBCs count (P = 0.01), Hb (P = 0.001), Hct (P = 0.0003), MCV (P = 0.013), lymphocyte count (P = 0.015), neutrophil count (P = 0.003), monocyte count (P = 0.012) and eosinophil count (P = 0.006). Histopathological studies have shown that in T1 group noticeable infiltration of inflammatory cells was found with low level of vascular damage. In T2 group, increased proportion of binucleated and inflammatory cells, hepatic necrosis, widening of sinusoidal spaces and mild level of vascular damage was observed.

CONCLUSION

Taken together these findings we can conclude that N. oleander leaves extract significantly affects on experimental animals due to its toxicity. Efforts must be exerted to purify different chemical components from extract with no inflammation as this plant is utilized in folk medicine with narrow therapeutic indices.

Sulforaphane increases the survival rate in rats with fulminant hepatic failure induced by D-galactosamine and lipopolysaccharide

Fulminant hepatic failure (FHF) is a life-threatening clinical syndrome, with liver transplantation being the only effective therapy. Sulforaphane (SFN) is a natural compound that is extracted from cruciferous vegetables and possesses potent anti-inflammatory, antioxidant, and anticancer activities. This study was designed to test the hypothesis that SFN (3 mg/kg) may protect against FHF induced in rats by administering a combination of D-galactosamine (GalN; 300 mg/kg) and lipopolysaccharide (LPS; 30 μg/kg). The rats were given a single intraperitoneal injection of SFN, 1 hour before the FHF induction. Sulforaphane reduced the mortality and alleviated the pathological liver injury. In addition, SFN significantly reduced the increase in serum aminotransferase activities and lipid peroxidation. The glutathione content decreased in the GalN/LPS group, and this decrease was attenuated by SFN. Increases in serum tumor necrosis factor α, interleukin-6, and interleukin-10, which were observed in GalN/LPS-treated rats, were significantly reduced after using SFN. The GalN/LPS treatment increased the expression of superoxide dismutase-1, glutathione peroxidase 2, catalase, and heme oxygenase-1 genes. Sulforaphane inhibited the induction of reactive oxygen species scavenging proteins. Moreover, SFN inhibited GalN/LPS-induced caspase-3 activation and suppressed FAS and FASL expression. These findings suggest that SFN alleviates GalN/LPS-induced liver injury, possibly by exerting antioxidant, anti-inflammatory, and antiapoptotic effects and modulating certain antioxidant defense enzymes.

Emodin ameliorated lipopolysaccharide-induced fulminant hepatic failure by blockade of TLR4/MD2 complex expression in D-galactosamine-sensitized mice

Emodin has been reported to possess anti-inflammatory and anti-oxidant activities. The aim of this study was to explore the effect and mechanism of emodin on lipopolysaccharide (LPS)-induced fulminant hepatic failure (FHF) in D-galactosamine (D-GalN)-sensitized mice. Our results showed that pretreatment with emodin inhibited the elevation of plasma aminotransferases, alleviated the hepatic histopathological abnormalities and improved the survival rate of LPS/D-GalN-primed mice. Moreover, emodin markedly attenuated the increased serum and hepatic tumor necrosis factor-α (TNF-α) production, and activated hepatic p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signal pathways in LPS/D-GalN-challenged mice. Furthermore, using an in vitro experiment, we found that emodin dose-dependently suppressed TNF-α production, dampened AP-1 and NF-κB activation, and blocked toll-like receptor (TLR) 4/myeloid differentiation factor (MD) 2 complex expression in LPS-elicited RAW264.7 mouse macrophage cells. Taken together, these data suggested that emodin could effectively prevent LPS-induced FHF, which might be mediated by inhibition of TNF-α production, deactivation of MAPKs and NF-κB, and blockade of TLR4/MD2 complex expression.

Protective effect of linarin against D-galactosamine and lipopolysaccharide-induced fulminant hepatic failure

Linarin was isolated from Chrysanthemum indicum L. Fulminant hepatic failure is a serious clinical syndrome that results in massive inflammation and hepatocyte death. Apoptosis is an important cellular pathological process in d-galactosamine (GalN)/lipopolysaccharide (LPS)-induced liver injury, and regulation of liver apoptosis might be an effective therapeutic method for fulminant hepatic failure. This study examined the cytoprotective mechanisms of linarin against GalN/LPS-induced hepatic failure. Mice were given an oral administration of linarin (12.5, 25 and 50mg/kg) 1h before receiving GalN (800 mg/kg)/LPS (40 μg/kg). Linarin treatment reversed the lethality induced by GalN/LPS. After 6h of GalN/LPS injection, the serum levels of alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor (TNF)-α, interleukin-6 and interferon-γ were significantly elevated. GalN/LPS increased toll-like receptor 4 and interleukin-1 receptor-associated kinase protein expression. These increases were attenuated by linarin. Linarin attenuated the increased expression of Fas-associated death domain and caspase-8 induced by GalN/LPS, reduced the cytosolic release of cytochrome c and caspase-3 cleavage induced by GalN/LPS, and reduced the pro-apoptotic Bim phosphorylation induced by GalN/LPS. However, linarin increased the level of anti-apoptotic Bcl-xL and phosphorylation of STAT3. Our results suggest that linarin alleviates GalN/LPS-induced liver injury by suppressing TNF-α-mediated apoptotic pathways.

BRP, a polysaccharide fraction isolated from Boschniakia rossica, protects against galactosamine and lipopolysaccharide induced hepatic failure in mice

The aim of this study was to investigate the hepatoprotective effect of BRP, a polysaccharide fraction isolated from Boschniakia rossica, against galactosamine and lipopolysaccharide induced fulminant hepatic failure. Mice were injected with a single dose of galactosamine/lipopolysaccharide with or without pretreatment of BRP. Results showed marked reduction of hepatic necrosis, serum marker enzymes and levels of tumor necrosis factor-α and interleukin-6 in BRP pretreated mice when compared with galactosamine/lipopolysaccharide-challenged mice. Mice pretreated with BRP decreased the activation of caspases-3 and caspase-8, and showed a reduced level of DNA fragmentation of liver cells. BRP also reduced hepatic lipid peroxidation, increased potential of hepatic antioxidative defense system, and reduced hepatic nitric oxide level which was elevated by galactosamine/lipopolysaccharide injection. Immunoblot analysis showed down-regulation of inducible nitric oxide synthase and cyclooxygenase-2 proteins of liver tissues in BRP pretreated group when compared with galactosamine/lipopolysaccharide-challenged group. Furthermore, treatment with galactosamine/lipopolysaccharide markedly increased toll-like receptor 4, nuclear level of nuclear factor-κB, and phosphorylation of both extracellular signal-regulated kinase and c-Jun N-terminal kinase in liver tissues. However, these increases were attenuated by pretreatment with BRP. The results suggest that BRP alleviates galactosamine/lipopolysaccharide-induced liver injury by enhancing antioxidative defense system, suppressing inflammatory responses and reducing apoptotic signaling.

Hepatoprotective effect of cryptotanshinone from Salvia miltiorrhiza in D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure

Cryptotanshinone from Salvia miltiorrhiza Bunge was investigated for hepatoprotective effects in d-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant hepatic failure. Cryptotanshinone (20 or 40 mg/kg) was orally administered 12 and 1h prior to GalN (700 mg/kg)/LPS (10 μg/kg) injection. The increased mortality and TNF-α levels by GalN/LPS were declined by cryptotanshinone pretreatment. In addition, cryptotanshinone attenuated GalN/LPS-induced apoptosis, characterized by the blockade of caspase-3, -8, and -9 activation, as well as the release of cytochrome c from the mitochondria. In addition, cryptotanshinone significantly suppressed JNK, ERK and p38 phosphorylation induced by GalN/LPS, and phosphorylation of TAK1 as well. Furthermore, cryptotanshinone significantly inhibited the activation of NF-κB and suppressed the production of proinflammatory cytokines. These findings suggested that hepatoprotective effect of cryptotanshinone is likely associated with its anti-apoptotic activity and the down-regulation of MAPKs and NF-κB associated at least in part with suppressing TAK1 phosphorylation.

IL-25 prevents and cures fulminant hepatitis in mice through a myeloid-derived suppressor cell-dependent mechanism

Fulminant hepatitis (FH) is a disease characterized by massive destruction of hepatocytes with severe impairment of liver function. The pathogenesis of FH is not fully understood, but hyperactivity of T cells and macrophages with excessive production of cytokines are important hallmarks of the condition. In this study, we investigated the role of interleukin (IL)-25 in FH. IL-25 expression was evaluated in patients with FH and in livers of mice with FH induced by D-galactosamine (D-Gal) and lipopolysaccharide (LPS). Mice were treated with IL-25 before D-Gal/LPS-induced FH and before or after concanavalin A (ConA)-induced FH. Mononuclear cells were isolated from livers of mice treated with or without IL-25 and analyzed for GR1(+) CD11b(+) cells. CFSE-labeled T cells were cocultured with GR1(+) CD11b(+) cells and their proliferation was evaluated by flow cytometry. Mice were also treated with a depleting anti-GR1 antibody before IL-25 and D-Gal/LPS administration. IL-25 was constitutively expressed in mouse and human liver and down-regulated during FH. IL-25 prevented D-Gal/LPS-induced FH and this effect was associated with increased infiltration of the liver with cells coexpressing GR1 and CD11b. In vitro studies showed that GR1(+) CD11b(+) cells isolated from mice given IL-25 inhibited T-cell proliferation. Consistently, in vivo depletion of GR1(+) cells abrogated the protective effect of IL-25 in experimental D-Gal/LPS-induced FH. IL-25 was both preventive and therapeutic in ConA-induced FH.

CONCLUSIONS

IL-25 expression is markedly reduced during human and experimental FH. IL-25 promotes liver accumulation of GR1(+) CD11b(+) cells with immunoregulatory properties.

Antagonism of the histamine H4 receptor reduces LPS-induced TNF production in vivo

Objective

Antagonism of the histamine H₄ receptor (H₄R) has been shown to be anti-inflammatory in a number of preclinical disease models, however the exact mechanisms behind this are still being uncovered. In vitro, the receptor interacts with TLR and impacts inflammatory mediator production from a number of different cell types. Here it is shown that this interaction also occurs in vivo.

Materials and methods

Wild-type and H₄R deficient BALB/c mice received an i.p. injection of LPS in PBS in conjunction with p.o. JNJ 7777120 or JNJ 28307474 (H₄R antagonists). Two hours later blood was collected and TNF was measured.

Results

Two different H₄R antagonists inhibited LPS-induced TNF production in mice and this production was also reduced in H₄R-deficient mice. The TNF mRNA analysis showed that the major source of the cytokine was the liver and not blood, and that the H₄R antagonist only reduced the expression levels in the liver. Depletion or inactivation of macrophages reduced the TNF levels and eliminated the H₄R sensitivity. Treatment with an H₄R antagonist also reduced LPS-induced liver injury and blocked LPS-enhanced lung inflammation in mice.

Conclusion

The data support an interaction between H₄R and TLR activation in vivo that can drive inflammatory responses.

Electronic supplementary material

The online version of this article (doi:10.1007/s00011-013-0612-5) contains supplementary material, which is available to authorized users.

Geniposidic acid protects against D-galactosamine and lipopolysaccharide-induced hepatic failure in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposidic acid (GA) is an iridoid glucoside isolated from Gardeniae jasminoides Ellis (Rubiaceae) that has long been used to treat inflammation, jaundice and hepatic disorders.

AIMS OF THE STUDY

This study examined the cytoprotective properties of GA against D-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant hepatic failure.

MATERIALS AND METHODS

Mice were given an intraperitoneal injection of GA (12.5, 25, 50 mg/kg) 1h before receiving GalN (800 mg/kg)/LPS (40 μg/kg). Liver and blood samples were collected 1 and 8 h after GalN/LPS injection.

RESULTS

The survival rate of the GA group was significantly higher than the control. GalN/LPS increased serum aminotransferase activity, serum tumor necrosis factor-α level and hepatic lipid peroxidation and decreased hepatic glutathione content. These changes were attenuated by GA. GA augmented increases in serum interleukin-6 level, heme oxygenase-1 and NF-E2-related factor 2 protein expression. Mice treated with GA decreased cleaved caspase-8 and caspase-3 protein expression and showed significantly fewer apoptotic cells. GA increased Bcl-xL protein expression and decreased Bax protein expression. Moreover, GA treatment enhanced phosphorylation of signal transducer and activator of transcription 3.

CONCLUSION

Our findings suggest that geniposidic acid alleviates GalN/LPS-induced liver injury by enhancing antioxidative defense system and reducing apoptotic signaling pathways.

Inhibition of glycogen synthase kinase 3β ameliorates D-GalN/LPS-induced liver injury by reducing endoplasmic reticulum stress-triggered apoptosis

Background

Glycogen synthase kinase 3β(GSK3β) is a ubiquitous serine-threonine protein kinase that participates in numerous cellular processes and disease pathophysiology. We aimed to determine therapeutic potential of GSK3β inhibition and its mechanism in a well-characterized model of lipopolysaccharide (LPS)-induced model of acute liver failure (ALF).

Methodology

In a murine ALF model induced by D-GalN(700 mg/kg)/LPS(10 µg/kg), we analyzed GSK3β mechanisms using a specific chemical inhibitor, SB216763, and detected the role of endoplasmic reticulum stress (ERS). Mice were administered SB216763 at 2 h before or after D-GalN/LPS injection, respectively, and then sacrificed 6 h after D-GalN/LPS treatment to evaluate its prophylactic and therapeutic function. The lethality rate, liver damage, ERS, cytokine expression, MAP kinase, hepatocyte apoptosis and expression of TLR 4 were evaluated, respectively. Whether the inhibition of GSK3β activation protected hepatocyte from ERS-induced apoptosis was investigated in vitro.

Principal Findings

GSK3β became quickly activated (dephosphorylated) upon D-GalN/LPS exposure. Administration of SB216763 not only ameliorated liver injury, as evidenced by reduced transaminase levels, and well-preserved liver architecture, but also decreased lethality. Moreover, GSK3β inhibition resulted in down-regulation of pro-apoptotic proteins C/EBP–homologous protein(CHOP) and caspase-12, which are related to ERS. To further demonstrate the role of ERS, we found that GSK3β inhibition protected hepatocyte from ERS-induced cell death. GSK3β inhibition down-regulated the MAPK pathways, reduced expression of inflammatory cytokines and decreased expression of TLR4.

Conclusions

Our findings demonstrate the key function of GSK3β signaling in the pathophysiology of ALF, especially in regulating the ERS, and provide a rationale for targeting GSK3β as a potential therapeutic strategy to ameliorate ALF.

Japonicone A antagonizes the activity of TNF-α by directly targeting this cytokine and selectively disrupting its interaction with TNF receptor-1

Anti-TNF biologics are effective therapies for various inflammatory diseases. Unfortunately, their clinical use is associated with an increased risk of infections. Selectively inhibiting TNF receptor-1 (TNFR1)-mediated signaling while preserving TNFR2 signaling may reduce inflammation yet maintain host immune response to pathogens. However, few small molecules that selectively target the TNF/TNFR system have been discovered. In the present study, we identified Japonicone A (Jap A), a nature compound derived from Inula japonica Thunb, as a novel TNF-α antagonist, as it reduced the TNF-α-mediated cytotoxicity on L929 cells and inhibited the binding of (125)I-labeled TNF-α to L929 cell surface. Furthermore, Jap A could directly bind to TNF-α rather than TNFR1 as determined by surface plasmon resonance. More importantly, Jap A could effectively inhibit the binding of TNF-α to TNFR1, while displaying only marginal inhibitory effects on that to TNFR2. Jap A also could block TNFR1-mediated signaling as it inhibited TNF-α-induced NF-κB activation in 293 cells. In addition, Jap A suppressed TNF-α-induced expressions of adhesion molecules (ICAM-1, VCAM-1) and chemokine (MCP-1) in the endothelial cells by blocking TNF-α-triggered multiple signaling pathways. Data from in vivo experiments demonstrated that Jap A protected mice from acute hepatitis induced by TNF-α/d-galactosamine, but did not compromise host antiviral immunity in adenovirus-infected mice. These results indicate that Jap A can directly target TNF-α, selectively disrupt its interaction with TNFR1, and antagonize its pro-inflammatory activities without compromising host defense against virus, thus emphasizing the potential of Jap A as an interesting lead compound for development of new anti-inflammatory drugs.

Ron receptor-dependent gene regulation in a mouse model of endotoxin-induced acute liver failure

BACKGROUND

Prior experimentation has shown that loss of the tyrosine kinase (TK) signaling domain of the Ron receptor leads to marked hepatocyte protection in a model of lipopolysaccharide-induced acute liver failure (ALF) in D-galactosamine (GalN)-sensitized mice. The aim of this study was to identify the role of Ron in the regulation of hepatic gene expression.

METHODS

Microarray analyses were performed on liver RNA isolated sequentially from wild-type (WT) and TK-/- mice during the progression of ALF. Gene array data were validated using Western and immunohistochemistry analyses as well as with ex vivo culture systems.

RESULTS

At baseline, 101 genes were differentially expressed between WT and TK-/- livers, which regulate processes involved in hypoxia, proliferation, apoptosis and metabolism. One hour after ALF induction, WT livers exhibited increased cytokine expression compared to TK-/- livers, and after 4 hours, an induction of suppressor of cytokine signaling (SOCS) genes as well as JAK-STAT pathway activation were prominent in TK-/- livers compared to controls.

CONCLUSION

Our studies suggest a novel hepato-protective mechanism in Ron TK-/- mice wherein increased and sustained SOCS production and JAK-STAT activation in the hepatocyte may inhibit the destructive proinflammatory milieu and promote survival factors which blunt hepatic death and the ensuing development of ALF.

The role of innate immunity in HBV infection

Hepatitis B virus (HBV) infection is one of the main causes of chronic liver diseases. Whether HBV infection is cleared or persists is determined by both viral factors and host immune responses. It becomes clear that innate immunity is of importance in protecting the host from HBV infection and persistence. However, HBV develops strategies to suppress the antiviral immune responses. A combined therapeutic strategy with both viral suppression and enhancement of antiviral immune responses is needed for effective long-term clearance and cure for chronic HBV infection. We and others confirmed that bifunctional siRNAs with both gene silencing and innate immune activation properties are beneficial for inhibition of HBV and represent a potential approach for treatment of viral infection. Understanding the nature of liver innate immunity and their roles in chronic HBV progression and HBV clearance may aid in the design of novel therapeutic strategies for chronic HBV infection.

Hepatoprotective effects of IL-22 on fulminant hepatic failure induced by d-galactosamine and lipopolysaccharide in mice

Interleukin-22 (IL-22), a member of the IL-10 cytokine family that is produced by activated Th22, Th1 and Th17 cells as well as natural killer cells, plays an important role in increase of innate immunity, protection from damage and enhancement of regeneration. Here, we examined the effects of IL-22 on acute liver failure model induced by d-galactosamine (GalN) and lipopolysaccharide (LPS). Administration of recombinant human IL-22 (rhIL-22) reduced the death rate markedly and prevented mice from severe hepatic injury, as evidenced by decreased serum alanine aminotransferase (ALT) and total bilirubin (T.Bil) activity as well as improved histological signs in liver. Furthermore, IL-22 treatment decreased the hepatic malondialdehyde (MDA) contents and increased the reduced glutathione levels. Serum tumor necrosis factor α (TNF-α) level and hepatic caspase-3 activity were significantly lower in mice administrated with IL-22. Moreover, IL-22 treatment significantly enhanced activation of STAT3 and up-regulated the expression of Bcl-xL, heme oxygenase-1 (HO-1) and redox factor-1 (Ref-1) in the liver injury induced by GalN/LPS. Collectively, these data indicate that IL-22 can provide critical protection against GalN/LPS-induced liver injury through anti-apoptotic, anti-oxidant and anti-inflammatory actions.

Protective effects of luteolin against apoptotic liver damage induced by D-galactosamine/lipopolysaccharide in mice

In this study, the protective effects of luteolin (1, a major component of Cirsium japonicum) were examined against d-galactosamine (GalN)/lipopolysaccharide (LPS)-induced fulminant hepatic failure. Mice received an intraperitoneal injection of 1 (25, 50, 100, and 200 mg·kg(-1)) 1 h before treatment with GalN (700 mg·kg(-1))/LPS (10 μg·kg(-1)). Treatment with GalN/LPS resulted in increased mortality and serum aminotransferase activity. These increases were attenuated by pretreatment with 1. Treatment with GalN/LPS induced an increase in the serum level of tumor necrosis factor-α (TNF-α) and protein expression of TNF-α receptor-associated death domain, and these increases were prevented by 1. In addition, 1 attenuated apoptosis induced by GalN/LPS treatment, which was analyzed using a caspase-3 and -8 activity assay, as well as by proapoptotic BH3-only protein and cytochrome c protein expression, and by a terminal deoxynuleotidyl transferase-mediated dUTP nick end-labeling method. After GalN/LPS injection, nuclear phosphorylated c-Jun levels showed a significant increase, which were attenuated by 1. The present findings suggest that luteolin ameliorates D-GalN/LPS-induced liver injury and that this protection is likely due to inhibition of the extrinsic and intrinsic apoptotic pathways.

Macrophages and tissue injury: agents of defense or destruction?

The past several years have seen the accumulation of evidence demonstrating that tissue injury induced by diverse toxicants is due not only to their direct effects on target tissues but also indirectly to the actions of resident and infiltrating macrophages. These cells release an array of mediators with cytotoxic, pro- and anti-inflammatory, angiogenic, fibrogenic, and mitogenic activity, which function to fight infections, limit tissue injury, and promote wound healing. However, following exposure to toxicants, macrophages can become hyperresponsive, resulting in uncontrolled or dysregulated release of mediators that exacerbate acute tissue injury and/or promote the development of chronic diseases such as fibrosis and cancer. Evidence suggests that the diverse activity of macrophages is mediated by distinct subpopulations that develop in response to signals within their microenvironment. Understanding the precise roles of these different macrophage populations in the pathogenic response to toxicants is key to designing effective treatments for minimizing tissue damage and chronic disease and for facilitating wound repair.

14-Deoxyandrographolide desensitizes hepatocytes to tumour necrosis factor-alpha-induced apoptosis through calcium-dependent tumour necrosis factor receptor superfamily member 1A release via the NO/cGMP pathway

BACKGROUND AND PURPOSE

Andrographis paniculata (AP) has been found to display hepatoprotective effect, although the mechanism of action of the active compounds of AP in this context still remains unclear. Here, we evaluated the hepatoprotective efficacy of 14-deoxyandrographolide (14-DAG), a bioactive compound of AP, particularly its role in desensitization of hepatocytes to tumour necrosis factor-alpha (TNF-alpha)-induced signalling of apoptosis.

EXPERIMENTAL APPROACH

TNF-alpha-mediated ligand receptor interaction in hepatocytes in the presence of 14-DAG was studied in vitro in primary hepatocyte cultures, with the help of co-immunoprecipitation, confocal microscopy and FACS analysis. Events associated with 14-DAG-induced TNFRSF1A release from hepatocytes were determined using immunoblotting, biochemical assay and fluorimetric studies. Pulse-chase experiments with radiolabelled TNF-alpha and detection of apoptotic nuclei by terminal transferase-mediated dUTP nick-end labelling were performed under in vivo conditions.

KEY RESULTS

14-DAG down-regulated the formation of death-inducing signalling complex, resulting in desensitization of hepatocytes to TNF-alpha-induced apoptosis. Pretreatment of hepatocytes with 14-DAG accentuated microsomal Ca-ATPase activity through induction of NO/cGMP pathway. This resulted in enhanced calcium influx into microsomal lumen with the formation of TNFRSF1A-ARTS-1-NUCB2 complex in cellular vesicles. It was followed by the release of full-length 55 kDa TNFRSF1A and a reduction in the number of cell surface TNFRSF1A, which eventually caused diminution of TNF-alpha signal in hepatocytes.

CONCLUSION AND IMPLICATION

Taken together, the results demonstrate for the first time that 14-DAG desensitizes hepatocytes to TNF-alpha-mediated apoptosis through the release of TNFRSF1A. This can be used as a strategy against cytokine-mediated hepatocyte apoptosis in liver dysfunctions.

Hepatoprotective effects of Sedum sarmentosum on D-galactosamine/lipopolysaccharide-induced murine fulminant hepatic failure

The hepatoprotective effects of sarmentosin-containing extracts of Sedum sarmentosum (SS) in D-galactosamine (D-GalN) / lipopolysaccharide (LPS)-induced fulminant hepatic failure mouse model. Pretreatment with SS markedly protected mice from lethal liver injury, which has known to be associated with an abrupt elevation of serum tumor necrosis factor (TNF)-α level. Indeed, SS significantly blocked the elevation of TNF-α and alanine aminotransferase and aspartate aminotransferase as well. SS also remarkably reduced number of apoptotic hepatocytes and DNA fragmentation in the liver, which correlated with blockade of caspase-3 activation. In addition, SS suppressed the increased expression of toll-like receptor 4 (TLR4). The activation of c-Jun NH(2)-terminal kinase, extracellular signal-regulated kinase, and p38 induced by D-GalN/LPS was also significantly suppressed by SS treatment. Furthermore, SS significantly inhibited the activation of nuclear factor-κB. In RAW 264.7 cells stimulated with LPS, TNF-α release and TLR4 expression was suppressed by SS pretreatment, which was in line with in vivo results. These findings suggested that SS prevents D-GalN/LPS-induced fulminant hepatic failure, and this protection is likely associated with its anti-apoptotic activity and the down-regulation of mitogen activated protein kinase activity associated at least in part with suppressing the transcription of LPS receptors.

Protective effects of Asiaticoside on acute liver injury induced by lipopolysaccharide/D-galactosamine in mice

Asiaticoside (AS), a triterpenoid product isolated from Centella asiatica, has been described to exhibit anti-in fl ammatory activities in several inflammatory models. However, the effects of AS on liver injury are poorly understood. The present study was undertaken to investigate whether AS is efficacious against Lipopolysaccharide (LPS) /D-galactosamine (D-GalN)-induced acute liver injury in mice and its potential mechanisms. AS (5, 10 and 20 mg/kg/d) was pretreated orally once daily for 3 days before LPS/D-GalN injected in mice. The mortality, hepatic tissue histology, plasma levels of Tumor necrosis factor-alpha (TNF-alpha) and alanine aminotransferase (ALT) and aspartate aminotransferase (AST), hepatic tissue TNF-alpha and caspase-3 activity were measured. Besides, western blotting analysis of phospho-p38 mitogen-activated protein kinase (phospho-p38 MAPK), phospho-c-jun N-terminal kinase (phospho-JNK) and phospho-extracellular signal regulated kinase (phospho-ERK) were determined. As a result, AS showed significant protection as evidenced by the decrease of elevated aminotransferases, hepatocytes apoptosis and caspase-3, alleviation of mortality and improvement of liver pathological injury in a dose-dependent manner. Further, we found that AS dose-dependently reduced the elevation of phospho-p38 MAPK, phospho-JNK, phospho-ERK protein and TNF-alpha mRNA expression in liver tissues and plasma TNF-alpha. These results suggest that AS has remarkable hepatoprotective effects on LPS/D-GalN-induced liver injury and the possible mechanism is related to inhibition of TNF-alpha and MAPKs.

Anti-apoptotic activity of gentiopicroside in D-galactosamine/lipopolysaccharide-induced murine fulminant hepatic failure

This study investigated the hepatoprotective effects of gentiopicroside on d-galactosamine (d-GalN) and lipopolysaccharide (LPS)-induced fulminant hepatic failure. Mice were administrated orally with gentiopicroside (40 or 80 mg/kg body weight) at 12h and 1h before d-GalN (700 mg/kg)/LPS (10 microg/kg) injection. Gentiopicroside markedly reduced the increases in serum aminotransferase activities and lipid peroxidation. The glutathione content decreased in d-GalN/LPS alone group, and this decrease was attenuated by gentiopicroside. Increases in serum tumor necrosis factor-alpha (TNF-alpha), which were observed in d-GalN/LPS alone group, were significantly reduced by gentiopicroside. Importantly, gentiopicroside attenuated d-GalN/LPS-induced apoptosis of hepatocytes, as estimated by the caspase-3 cleavage, poly(ADP-ribose) polymerase (PARP) cleavage, and DNA fragmentation. d-GalN/LPS-induced caspase-8 and -9 activation was significantly suppressed by gentiopicroside. Moreover, increased cytosolic cytochrome c protein was reduced by gentiopicroside. Also, the increased ratio of Bax and Bcl-2 protein was significantly attenuated by gentiopicroside. After 6h of d-GalN/LPS injection, phosphorylated c-jun N-terminal kinase (JNK) and extracellular signal regulated kinase (ERK) was significantly increased, whereas phosphorylation JNK and ERK were attenuated by gentiopicroside. Our results suggest that gentiopicroside offers remarkable hepatoprotection against damage induced by d-GalN/LPS related with its anti-apoptotic activities.

In vitro inhibition of lipopolysaccharide and mycobacterium bovis bacillus Calmette Guérin-induced inflammatory cytokines and in vivo protection from D-galactosamine/LPS -mediated liver injury by the medicinal plant Sclerocarya birrea

Sclerocarya birrea is a medicinal plant used for the treatment of inflammatory- and bacterial-related diseases. The present study investigated in vitro and in vivo the effects of the stem bark methanol extract of S. birrea. Nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by bone marrow-derived macrophages (BMDM) pre-incubated with or without S. birrea, and stimulated with Lipopolysaccharide (LPS) or infected with live Mycobacterium bovis Bacillus Calmette Guérin (BCG) was evaluated. S. birrea extract inhibited, in a concentration-dependent manner, nitrite, TNF, IL-1beta, IL-6 and IL-12p40 production by BMDM stimulated with LPS or infected with live BCG. The iNOS expression was reduced by S. birrea after stimulation of BMDM with LPS. In addition, S. birrea inhibited the nuclear factor kB (NF-kB) activation by both LPS and BCG. The effects of the plant extract were also evaluated in an in vivo model of liver injury induced by D-galactosamine/LPS (D-GalN/LPS) administration in mice. S. birrea limited D-GalN/LPS-liver injury as assessed by a reduction in transaminases and TNF, IL-1beta, IL-6 serum levels, and translocation of NF-kB to the nucleus. Taken together, our data indicate that stem bark methanol extract of S. birrea possesses anti-inflammatory properties by inhibiting NF-kB activation and cytokine release induced by inflammatory or infectious stimuli.

Protective effects of quercetin on liver injury induced by ethanol

Quercetin, a natural compound of multiple origins, has broad biopharmacological effects, such as antioxidant, directly scavenging free radical, and hepatoprotectivity effects. This study is designed to investigate the interveneous effect of quercetin on liver injury induced by ethanol in rats. The rats that were orally treated with 50% ethanol for continuous ten days, which resulted in cell necrosis, fibrosis and inflammatory infiltration, were included in this study. Higher contents of AST, ALT ADH, γ-GT, TG in plasma and MDA in liver tissue, and lower content of GSH in liver tissue were highlighted in ethanol-treated rats when compared with healthy ones. The levels of cytokines such as IL-1β, IL-1, IL-6, IL-8, and TNF-α in rats plasma were also significantly enhanced, and level of IL-10 was obviously lowered through ethanol treatment. By preventive and synchronism treatment with quercetin for fourteen days, the contents of AST, ALT ADH, γ-GT, TG and MDA, and levels of IL-1β, IL-1, IL-6, IL-8, and TNF-α were significantly reduced, whereas GSH and level of IL-10 were obviously increased. It may be deduced that quercetin, by multiple mechanisms interplay, demonstrated somewhat protective effect on liver injury induced by ethanol in rats.

Macrophages and inflammatory mediators in chemical toxicity: a battle of forces

Macrophages function as control switches of the immune system, providing a balance between pro- and anti-inflammatory responses. To accomplish this, they develop into different subsets: classically (M1) or alternatively (M2) activated macrophages. Whereas M1 macrophages display a cytotoxic, proinflammatory phenotype, much like the soldiers of The Dark Side of The Force in the Star Wars movies, M2 macrophages, like Jedi fighters, suppress immune and inflammatory responses and participate in wound repair and angiogenesis. Critical to the actions of these divergent or polarized macrophage subpopulations is the regulated release of inflammatory mediators. When properly controlled, M1 macrophages effectively destroy invading pathogens, tumor cells, and foreign materials. However, when M1 activation becomes excessive or uncontrolled, these cells can succumb to The Dark Side, releasing copious amounts of cytotoxic mediators that contribute to disease pathogenesis. The activity of M1 macrophages is countered by The Force of alternatively activated M2 macrophages, which release anti-inflammatory cytokines, growth factors, and mediators involved in extracellular matrix turnover and tissue repair. It is the balance in the production of mediators by these two macrophage subpopulations that ultimately determines the outcome of the tissue response to chemical toxicants.

Role of monocytes and macrophages in experimental and human acute liver failure

Acute liver failure (ALF) is a devastating clinical syndrome characterised by progressive encephalopathy, coagulopathy, and circulatory dysfunction, which commonly leads to multiorgan failure and death. Central to the pathogenesis of ALF is activation of the immune system with mobilisation of cellular effectors and massive production of cytokines. As key components of the innate immune system, monocytes and macrophages are postulated to play a central role in the initiation, progression and resolution of ALF. ALF in humans follows a rapidly progressive clinical course that poses inherent difficulties in delineating the role of these pivotal immune cells. Therefore, a number of experimental models have been used to study the pathogenesis of ALF. Here we consider the evidence from experimental and human studies of ALF on the role of monocytes and macrophages in acute hepatic injury and the ensuing extrahepatic manifestations, including functional monocyte deactivation and multiple organ failure.