Mechanisms of inflammatory liver injury: adhesion molecules and cytotoxicity of neutrophils

Good Cells Go Bad: Immune Dysregulation in the Transition from Acute Liver Injury to Liver Failure After Acetaminophen Overdose

The role of inflammatory cells and other components of the immune system in acetaminophen (APAP)-induced liver injury and repair has been extensively investigated. Although this has resulted in a wealth of information regarding the function and regulation of immune cells in the liver after injury, apparent contradictions have fueled controversy around the central question of whether the immune system is beneficial or detrimental after APAP overdose. Ultimately, this may not be a simple assignment of "good" or "bad." Clinical studies have clearly demonstrated an association between immune dysregulation and a poor outcome in patients with severe liver damage/liver failure induced by APAP overdose. To date, studies in mice have not uniformly replicated this connection. The apparent disconnect between clinical and experimental studies has perhaps stymied progress and further complicated investigation of the immune system in APAP-induced liver injury. Mouse models are often dismissed as not recapitulating the clinical scenario. Moreover, clinical investigation is most often focused on the most severe APAP overdose patients, those with liver failure. Notably, recent studies have made it apparent that the functional role of the immune system in the pathogenesis of APAP-induced liver injury is highly context dependent and greatly influenced by the experimental conditions. In this review, we highlight some of these recent findings and suggest strategies seeking to resolve and build on existing disconnects in the literature. SIGNIFICANCE STATEMENT: Acetaminophen overdose is the most frequent cause of acute liver failure in the United States. Studies indicate that dysregulated innate immunity contributes to the transition from acute liver injury to acute liver failure. In this review, we discuss the evidence for this and the potential underlying causes.

Measurement of Cell Death in Mammalian Cells

Methods for assessing mammalian cell death are presented in this article, which is divided into six sections: (1) a brief overview of cytotoxicity and pathways of cell death; (2) a method to measure cell death using lactate dehydrogenase (LDH) release as a marker of membrane integrity; (3) a flow cytometry method that simultaneously measures two types of cell death, necrosis and apoptosis; (4) use of fluorescence microscopy and nuclear morphology to assess apoptosis and necrosis; (5) the use of multi-well plates and high-content analysis imaging systems to assess nuclear morphology; and (6) a discussion of the use of cytotoxicity assays to determine the mechanisms of cell death. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Measurement of plasma membrane integrity and viability using LDH release Basic Protocol 2: Measurement of necrosis and apoptosis using flow cytometry Basic Protocol 3: Determination of nuclear morphology and membrane integrity Alternate Protocol 1: Assessment of nuclear morphology and membrane integrity using DAPI and PI Alternate Protocol 2: Assessment of nuclear morphology using multi-well plates Basic Protocol 4: Measurement of time-dependent toxicity using cell death markers.

Hepatoprotective effect of Moringa oleifera leaves aquatic extract against lead acetate-induced liver injury in male Wistar rats

Current research was performed to explore the hepatoprotective potential of Moringa oleifera leaves extract on lead acetate-induced hepatic injury. Twenty-four male Wistar rats were divided equally into 4 groups. The first group was control, while the second, third, and fourth groups were given 200 mg/kg aqueous Moringa extract only, 100 mg/kg lead only, and 100 mg/kg lead plus 200 mg/kg aqueous Moringa leaves extract, respectively, via oral gavage for 4 weeks. Weight gain and feed efficiency ratio were recorded. Serum lipid profiles, liver enzyme activities, and proteins beside hepatic superoxide dismutase activity, reduced glutathione, tumor necrosis factor alpha (TNF-α), and deoxyribonucleic acid fragmentation were assessed. Liver histopathological examination and nuclear factor kappa B (NF-kB) immunohistochemistry were performed. Administration of lead lowered (P < 0.05) weight gain, feed efficiency ratio, and perturbed lipid profile than control. Lead increased liver enzyme activities and TNF-α, while reduced serum proteins and hepatic antioxidant markers compared to control. Lead aggravated hepatic DNA fragmentation beside the presence of histopathological lesions. Co-administration of aqueous Moringa extract with lead significantly alleviated lead-induced adverse effects. The administration of aqueous Moringa extract with its antioxidant significantly restored the lead perturbations through reduction of oxidative stress-induced DNA damage via amelioration of NF-kB and TNF-α which kept hepatocyte integrity and reduced serum hepatic enzyme activities.

Protective effects of spironolactone against hepatic ischemia/reperfusion injury in rats

Objectives

In the present study, it was aimed to study the antioxidant effects of spironolactone (SPL) to determine its possible protective effects in hepatic ischemia reperfusion injury.

Material and Methods

Hepatic artery, portal vein, and bile duct of Wistar albino rats were clamped for 45 minutes under anesthesia to form an ischemia period. Then reperfusion was allowed and the rats were decapitated 60 minutes later. SPL (20 mg/kg, p.o.) or SF was orally administered for 30 minutes before ischemia. Rats in the control arm underwent sham surgery and were administered isotonic saline. Liver function was studied by measuring aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-α), and interleukin 1beta (IL-1β) levels. Malondialdehyde (MDA), glutathione (GSH), luminol, and lucigenin levels, myeloperoxidase (MPO) and Na+-K+-ATPase enzyme activities were analyzed to study tissue injury under light microscope.

Results

While IR increased AST, ALT, TNF-α, and IL-1β levels and MDA, luminol, and lusigenin levels and MPO activities, it caused a decrease in GSH levels and Na+K+-ATPase activity. Spironolactone administration significantly improved these values.

Conclusion

Protective effects of SPL against ischemia/reperfusion injury via various mechanisms suggest that this agent may become a novel treatment agent in clinical practice.

Influence of nanostructured calcium aluminate and calcium silicate on the liver: histological and unbiased stereological analysis

AIM

To examine the potential systemic toxicity of nanostructured materials based on calcium silicate and calcium aluminate, for potential application in Dentistry.

METHODOLOGY

Twenty-four Albino Wistar rats aged 2 months were used as an in vivo animal model for subcutaneous implantation of the investigated materials, placed in polyethylene tubes. Thirty days after implantation, the livers of the rats were analysed and following histological and stereological parameters were evaluated for volume density of hepatocytes and blood sinusoids, number and numerical density of hepatocytes, surface of hepatocytes and their nucleuses, nucleocytoplasmic ratio and mitotic index of hepatocytes. Stereological measurements were achieved using Cavalieri's principle, with grid P2 and unbiased analysis. Additionally, immunohistochemistry studies were performed to further analyse changes in liver tissue. Several haematological and biochemical parameters of blood of experimental animals were also analysed, as well as local tissue reactions around the implants. Statistical analysis was performed using parametric (anova and t-test) and nonparametric tests (Kruskal-Wallis and Mann-Whitney U-test) depending on data distribution.

RESULTS

Implanted dental cements led to an increase in stereological and histological parameters in liver tissue compared to control rats. Although the investigated parameters mostly showed significant differences between control and experimental animals, the liver tissue of the experimental animals did not have visible signs of pathological changes. This was supported by the analysis of blood parameters which were not significantly different between control and experimental animals. Also, the subcutaneous tissues had minimal inflammatory reactions. Immunohistochemistry studies revealed that nanostructured materials induced proliferation of hepatocytes, but that the immunological response to the materials was not strong enough to induce proliferation of immunoreactive cells in liver in the observed time period.

CONCLUSIONS

This study was performed as a contribution to the attestation of the biocompatibility of dental cements based on calcium silicate and calcium aluminate. Although these materials induced several changes in the liver structure, they were not clinically relevant and represent a normal and reversible response of the liver to the presence of biocompatible materials in the body. Blood and immunohistochemistry analyses and local tissue reactions further confirmed that these materials possess good biocompatible potential.

Repressor and activator protein accelerates hepatic ischemia reperfusion injury by promoting neutrophil inflammatory response

Repressor and activator protein (Rap1) directly regulates nuclear factor-κB (NF-κB) dependent signaling, which contributes to hepatic IRI. We here intended to investigate the effect of Rap1 in hepatic ischemia reperfusion injury (IRI) and to explore the underlying mechanisms. The association of Rap1 expression with hepatic inflammatory response were investigated in both human and rat liver transplantation. The effect of Rap1 in hepatic IRI was studied in Rap1 knockout mice IRI model in vivo and primary cells in vitro. Our results showed that over expression of Rap1 was associated with severe liver graft inflammatory response, especially in living donor liver transplantation. The results were also validated in rat liver transplantation model. In mice hepatic IRI model, the knockout of Rap1 reduced hepatic damage and hepatic inflammatory response. In primary cells, the knockout of Rap1 suppressed neutrophils migration activity and adhesion in response to liver sinusoidal endothelial cells through down-regulating neutrophils F-Actin expression and CXCL2/CXCR2 pathway. In addition, the knockout of Rap1 also decreased production of pro-inflammatory cytokines/chemokines in primary neutrophils and neutrophils-induced hepatocyte damage. In conclusion, Rap1 may induce hepatic IRI through promoting neutrophils inflammatory response. Rap1 may be the potential therapeutic target of attenuating hepatic IRI.

Houttuynia cordata Facilitates Metformin on Ameliorating Insulin Resistance Associated with Gut Microbiota Alteration in OLETF Rats

Metformin and Houttuynia cordata are representative anti-diabetic therapeutics in western and oriental medicine, respectively. The current study examined the synergistic anti-diabetic effect of Houttuynia cordata extraction (HCE) and metformin combination in Otsuka Long–Evans Tokushima Fatty (OLETF) rats. Fecal microbiota were analyzed by denaturing gradient gel electrophoresis (DGGE) and real-time PCR. Combining HCE + metformin resulted in significantly ameliorated glucose tolerance (oral glucose tolerance test (OGTT))—the same as metformin alone. Particularly, results of the insulin tolerance test (ITT) showed that combining HCE + metformin dramatically improved insulin sensitivity as compared to metformin treatment alone. Both fecal and serum endotoxin, as well as cytokines (tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6)) were significantly ameliorated by HCE + metformin compared to metformin alone. Meanwhile, the activation of AMPK (adenosine monophosphate-activated protein kinase) by metformin was distinctly enhanced by HCE. Both of HCE and metformin evidently changed the gut microbiota composition, causing the alteration of bacterial metabolite, like short-chain fatty acids. H. cordata, together with metformin, exerts intensive sensibilization to insulin; the corresponding mechanisms are associated with alleviation of endotoxemia via regulation of gut microbiota, particularly Roseburia, Akkermansia, and Gram-negative bacterium.

Antihypercholesterolemic Effects of Fruit Aqueous Extract of Copernicia prunifera (Miller) H. E. Moore in Mice Diet-Induced Hypercholesterolemia

The present objective of the investigation is to evaluate the antihypercholesterolemic activity of the aqueous fruit pulp extract (APE) of Copernicia prunifera (Miller) H. E. Moore (Arecaceae family). Various chemical characterization methods like thin layer chromatography, Fourier transform infrared spectroscopy, 1H and 13C NMR, and molecular weight by gel permeation chromatography have been employed to characterize the extracted pectin. The present study demonstrated that hypercholesterolemic diet (HD) created hypercholesterolemia, caused significant increases in body weight, total cholesterol, and low-density lipoprotein, and caused decreases in high-density lipoprotein in serum compared with SD group. Two doses (APE 150 and 300 mg/Kg b.w./day) were administered to hyperlipidemic mice for 90 days. APE reversed body weight changes, changed serum lipids to normal values, and significantly inhibited the changes of lipid peroxidation and inflammation in the liver tissues. The renal parameters analyzed (urea and creatinine) altered by diet were reverted to normal values. Our results revealed that aqueous fruit pulp extracts of carnauba reduced hypercholesterolemia showing a potential preventive effect against cardiovascular diseases without side effects cause.

Possible Involvement of Nitric Oxide in Enhanced Liver Injury and Fibrogenesis during Cholestasis in Cytoglobin-deficient Mice

This study clarified the role of Cygb, the fourth globin in mammals originally discovered in rat hepatic stellate cells (HSCs), in cholestatic liver disease. Bile duct ligation (BDL) augmented inflammatory reactions as revealed by increased infiltrating neutrophils, CD68⁺-macrophages, and chemokine expression in Cygb^-/- mice. In these mice, impairment of bile canalicular indicated by the loss of CD10 expression, down-regulation of bile salt transporters, increased total bile acid, and massive apoptotic and necrotic hepatocytes occurred with the release of cytochrome c, activation of caspase 3, resulting in reduced animal survival compared to wild-type mice. In Cygb^-/- mouse liver, all of NO metabolites and oxidative stress were increased. Treatment with NO inhibitor restrained all above phenotypes and restored CD10 expression in BDL Cygb^-/- mice, while administration of NO donor aggravated liver damage in BDL-wild type mice to the same extent of BDL-Cygb^-/- mice. N-acetylcysteine administration had a negligible effect in all groups. In mice of BDL for 1-3 weeks, expression of all fibrosis-related markers was significantly increased in Cygb^-/- mice compared with wild-type mice. Thus, Cygb deficiency in HSCs enhances hepatocyte damage and inflammation in early phase and fibrosis development in late phase in mice subjected to BDL, presumably via altered NO metabolism.

The anti-TNF-α antibody infliximab inhibits the expression of fat-transporter-protein FAT/CD36 in a selective hepatic-radiation mouse model

Previously, we reported a radiation-induced inflammation triggering fat-accumulation through fatty-acid-translocase/cluster of differentiation protein 36 (FAT/CD36) in rat liver. Furthermore, inhibition of radiation-induced FAT/CD36-expression by anti-tumor necrosis factor-α (anti-TNF-α) (infliximab) was shown in vitro. The current study investigates fat-accumulation in a mouse-model of single-dose liver-irradiation (25-Gray) and the effect of anti-TNF-α-therapy on FAT/CD36 gene-expression. Mice livers were selectively irradiated in vivo in presence or absence of infliximab. Serum- and hepatic-triglycerides, mRNA, and protein were analyzed by colorimetric assays, RT-PCR, Immunofluorescence and Western-Blot, respectively. Sudan-staining was used demonstrating fat-accumulation in tissue. In mice livers, early (1–3 h) induction of TNF-α-expression, a pro-inflammatory cytokine, was observed. It was followed by elevated hepatic-triglyceride level (6–12 h), compared to sham-irradiated controls. In contrast, serum-triglyceride level was decreased at these time points. Similar to triglyceride level in mice livers, Sudan staining of liver cryosections showed a quick (6–12 h) increase of fat-droplets after irradiation. Furthermore, expression of fat-transporter-protein FAT/CD36 was increased at protein level caused by radiation or TNF-α. TNF-α-blockage by anti-TNF-α showed an early inhibition of radiation-induced FAT/CD36 expression in mice livers. Immunohistochemistry showed basolateral and cytoplasmic expression of FAT/CD36 in hepatocytes. Moreover, co-localization of FAT/CD36 was detected with α-smooth muscle actin (α-SMA⁺) cells and F4/80⁺ macrophages. In summary, hepatic-radiation triggers fat-accumulation in mice livers, involving acute-phase-processes. Accordingly, anti-TNF-α-therapy prevented early radiation-induced expression of FAT/CD36 in vivo.

Quinoid derivatives of the nevirapine metabolites 2-hydroxy- and 3-hydroxy-nevirapine: activation pathway to amino acid adducts

Quinoid electrophiles from the nevirapine metabolites, 2-OH- and 3-OH-nevirapine, react with nitrogen-based bionucleophiles yielding covalent adducts.

Free radical scavengers improve liver function but not morphological changes induced by reperfusion injury

OBJECTIVE

Reperfusion injury (RI) is associated with high generation of reactive oxygen species (ROS), but the extent of involvement of these agents in the injury remains controversial. The present study aimed to examine the effectiveness of ROS scavengers against hepatic reperfusion injury in the rat.

METHODS

The RI was induced in the liver using an isolated slow-flow, reflow perfused rat liver in both anterograde and retrograde perfusion. The effects of gentisic acid, N-acetyl cysteine, and trolox C on the superoxide production, liver function, and morphological changes were examined using different biochemical and histological assays.

RESULTS

The hepatic RI caused a significant (p < 0.05) increase in superoxide production and enzyme releases and a decrease in bile flow in both directions. Histological changes induced by RI include apoptosis, necrosis, pale cytoplasm, cell vacuolation, and attenuation of cell cords. Although the production of superoxide in retrograde direction was significantly less than the anterograde, the extent of the injury in the retrograde was greater than the anterograde direction. Pretreatment of the livers with each of the test compounds significantly reduced the release of lactate dehydrogenase and aspartate aminotransferase and improved bile flow in the liver exposed to hypoxia/reperfusion. However, they failed to protect the liver against the structural alterations induced by RI.

CONCLUSION

ROS scavengers can reduce superoxide-induced damage and improve the liver function, but they are not able to prevent the structural changes. It shows that ROS are not the sole causative mechanism of hepatic RI and other mechanisms and mediators may be involved.

Investigation into the role of the cholinergic system in radiation-induced damage in the rat liver and ileum

It has been previously shown that acetylcholine (ACh) may affect pro-inflammatory and anti-inflammatory cytokines. The role of the cholinergic system in radiation-induced inflammatory responses and tissue damage remains unclear. Therefore, the present study was designed to determine the radio-protective properties of the cholinergic system in the ileum and the liver of rats. Rats were exposed to 8-Gy single-fraction whole-abdominal irradiation and were then decapitated at either 36 h or 10 d post-irradiation. The rats were treated either with intraperitoneal physiological saline (1 ml/kg), physostigmine (80 µg/kg) or atropine (50 μg/kg) twice daily for 36 h or 10 d. Cardiac blood samples and liver and ileal tissues were obtained in which TNF-α, IL-1β and IL-10 levels were assayed using ELISA. In the liver and ileal homogenates, caspase-3 immunoblots were performed and myeloperoxidase (MPO) activity was analyzed. Plasma levels of IL-1β and TNF-α increased significantly following radiation (P < 0.01 and P < 0.001, respectively) as compared with non-irradiated controls, and physostigmine treatment prevented the increase in the pro-inflammatory cytokines (P < 0.01 and P < 0.001, respectively). Plasma IL-10 levels were not found to be significantly changed following radiation, whereas physostigmine augmented IL-10 levels during the late phase (P < 0.01). In the liver and ileum homogenates, IL-1β and TNF-α levels were also elevated following radiation, and this effect was inhibited by physostigmine treatment but not by atropine. Similarly, physostigmine also reversed the changes in MPO activity and in the caspase-3 levels in the liver and ileum. Histological examination revealed related changes. Physostigmine experiments suggested that ACh has a radio-protective effect not involving the muscarinic receptors.

Mechanisms of Acute Liver Failure

Acute liver failure (ALF) is characterized by the sudden onset of liver failure in a patient without evidence of chronic liver disease. This definition is important, as it differentiates patients with ALF from patients who suffer from liver failure owing to end-stage chronic liver disease [1].

The protective effects of n-acetylcysteine against acute hepatotoxicity

OBJECTIVES

N-acetylcysteine (NAC) increases tissue levels of glutathione and has been widely investigated as a protective and antioxidative agent. This study evaluated the protective effect of NAC on under carbon tetrachloride (CCl4)-induced acute liver injury in the rat.

METHODS

Three-month-old Sprague-Dawley rats were intraperitoneally administered 4 mL/kg CCl4 (1:1 dissolved in olive oil, group 1) or 4 mL/kg CCl4 + NAC 150 mg/kg, 3 and 6 h after CCL4 (group 2) or 4 mL/kg olive oil (group 3, control). Twenty-four hours after administering CCl4, all of the rats were sacrificed. Biochemical assessment of serum transaminases and malonaldehyde (MDA) and tissue MDA, myeloperoxidase (MPO), and nitric oxide was done. Histopathological assessments were performed.

RESULTS

Serum transaminases and tissue and serum MDA and tissue MPO were all increased in group 1 compared to control and were significantly decreased in the group treated with NAC. Histopathological comparison of the groups showed a decrease in congestion, polymorphonuclear leukocytes, mononuclear leukocytes, vacuolar degeneration of hepatocyte, and hepatocellular necrosis in the group treated with NAC.

CONCLUSION

Our results suggest that NAC prevents experimental acute hepatic failure by preventing oxidative stress.

Hydrogen sulfide modulates sinusoidal constriction and contributes to hepatic microcirculatory dysfunction during endotoxemia

Hydrogen sulfide (H₂S) affects vascular resistance; however, its effect on the hepatic microcirculation has not been investigated. Hepatic sinusoidal perfusion is dysregulated during sepsis, contributing to liver injury. Therefore, the present study determined the effect of H₂S on the hepatic microcirculation and the contribution of endogenous H₂S to hepatic microcirculatory dysfunction in an endotoxin model of sepsis. Portal infusion of H₂S increased portal pressure in vivo (6.8 ± 0.2 mmHg before H₂S vs. 8.6 ± 0.8 mmHg peak during H₂S infusion, P < 0.05). Using intravital microscopy, we observed decreased sinusoidal diameter (6.2 ± 0.27 μm before H₂S vs. 5.7 ± 0.3 μm after H₂S, P < 0.05) and increased sinusoidal heterogeneity during H₂S infusion (P < 0.05) and net constriction. Since hepatic H₂S levels are elevated during sepsis, we used the cystathionine γ lyase inhibitor DL-propargylglycine (PAG) to determine the contribution of H₂S to the hypersensitization of the sinusoid to the vasoconstrictor effect of endothelin-1 (ET-1). PAG treatment significantly attenuated the sinusoidal sensitization to ET-1 in endotoxin-treated animals. ET-1 infusion increased portal pressure to 175% of baseline in endotoxemic animals, which was reduced to 143% following PAG treatment (P < 0.05). PAG abrogated the increase in sinusoidal constriction after ET-1 infusion in LPS-treated rats (30.9% reduction in LPS rats vs. 11.6% in PAG/LPS rats, P < 0.05). Moreover, PAG treatment significantly attenuated the increase in NADH fluorescence following ET-1 exposure during endotoxemia (61 grayscale units LPS vs. 21 units in PAG/LPS, P < 0.05), suggesting an improvement in hepatic oxygen availability. This study is the first to demonstrate a vasoconstrictor action of H₂S on the hepatic sinusoid and provides a possible mechanism for the protective effect of PAG treatment during sepsis.

Overview of hepatotoxicity

This overview presents some of the salient features of liver biology and physiology that form the basis for a variety of experimental tools that are used for the study of chemical histopathology. Prevalence and risk of heptatoxicity are examined among a subset of chemicals from the EPA IRIS database. The goal is to provide an objective assessment of the magnitude of the problem of chemically-induced hepatotoxicity and contextual background against which the diversity of responses of the liver to toxicants and the analytical methods available for their study can be appreciated.

A comparison of hepatic ischemia/hypoxia-reperfusion injury models

INTRODUCTION

A number of hepatic ischemia/hypoxia-reperfusion models have been described. This study characterised the functional and structural changes induced by the most commonly used in vivo and in situ models for hypoxia/ischemia-reperfusion in the rat liver.

METHODS

A range of no-flow, slow-flow and lobar ischemia and reperfusion models were established in the rat liver. Changes following reperfusion were monitored using physiological, biochemical, histological and pharmacological assessments, including bile production, oxygen consumption, lignocaine extraction, enzyme release, and disposition of exogenous markers.

RESULTS

Short periods of hepatic ischemia/hypoxia-reperfusion led to minimal changes in liver function whereas long periods of ischemia-reperfusion led to substantial liver injury. The most severe injury was found with the slow flow, reflow model. The formation of cell vacuoles, blebs and focal hepatitis were the most important liver morphological changes observed as a consequence of ischemia/hypoxia. The major liver histological findings after reperfusion were dispersed apoptosis and local necrosis. Hepatic ischemia/hypoxia-reperfusion was also associated with significant changes in the hepatic extracellular and intracellular spaces.

DISCUSSION

The morphology and function of the liver associated with a range of hepatic ischemia/hypoxia-reperfusion models varies with the duration of the insult and between models. The choice of model is therefore an important consideration in seeking to resolve any particular hypothesis associated with hepatic ischemia/hypoxia-reperfusion.

Gene expression profiling of whole blood in ipilimumab-treated patients for identification of potential biomarkers of immune-related gastrointestinal adverse events

BACKGROUND

Treatment with ipilimumab, a fully human anti-CTLA-4 antibody approved for the treatment of advanced melanoma, is associated with some immune-related adverse events (irAEs) such as colitis (gastrointestinal irAE, or GI irAE) and skin rash, which are managed by treatment guidelines. Nevertheless, predictive biomarkers that can help identify patients more likely to develop these irAEs could enhance the management of these toxicities.

METHODS

To identify candidate predictive biomarkers associated with GI irAEs, gene expression profiling was performed on whole blood samples from 162 advanced melanoma patients at baseline, 3 and 11 weeks after the start of ipilimumab treatment in two phase II clinical trials (CA184004 and CA184007). Overall, 49 patients developed Grade 2 or higher (grade 2+) GI irAEs during the course of treatment. A repeated measures analysis of variance (ANOVA) was used to evaluate the differences in mean expression levels between the GI irAE and No-GI irAE groups of patients at the three time points.

RESULTS

In baseline samples, 27 probe sets showed differential mean expression (≥ 1.5 fold, P ≤ 0.05) between the GI irAE and No-GI irAE groups. Most of these probe sets belonged to three functional categories: immune system, cell cycle, and intracellular trafficking. Changes in gene expression over time were also characterized. In the GI irAE group, 58 and 247 probe sets had a ≥ 1.5 fold change in expression from baseline to 3 and 11 weeks after first ipilimumab dose, respectively. In particular, on-treatment expression increases of CD177 and CEACAM1, two neutrophil-activation markers, were closely associated with GI irAEs, suggesting a possible role of neutrophils in ipilimumab-associated GI irAEs. In addition, the expression of several immunoglobulin genes increased over time, with greater increases in patients with grade 2+ GI irAEs.

CONCLUSIONS

Gene expression profiling of peripheral blood, sampled before or early in the course of treatment with ipilimumab, resulted in the identification of a set of potential biomarkers that were associated with occurrence of GI irAEs. However, because of the low sensitivity of these biomarkers, they cannot be used alone to predict which patients will develop GI irAEs. Further investigation of these biomarkers in a larger patient cohort is warranted.

Innate immune cells in liver inflammation

Innate immune system is the first line of defence against invading pathogens that is critical for the overall survival of the host. Human liver is characterised by a dual blood supply, with 80% of blood entering through the portal vein carrying nutrients and bacterial endotoxin from the gastrointestinal tract. The liver is thus constantly exposed to antigenic loads. Therefore, pathogenic microorganism must be efficiently eliminated whilst harmless antigens derived from the gastrointestinal tract need to be tolerized in the liver. In order to achieve this, the liver innate immune system is equipped with multiple cellular components; monocytes, macrophages, granulocytes, natural killer cells, and dendritic cells which coordinate to exert tolerogenic environment at the same time detect, respond, and eliminate invading pathogens, infected or transformed self to mount immunity. This paper will discuss the innate immune cells that take part in human liver inflammation, and their roles in both resolution of inflammation and tissue repair.

Xanthohumol suppresses inflammatory response to warm ischemia-reperfusion induced liver injury

Liver ischemia/reperfusion (I/R) leads to formation of reactive oxygen species (ROS), which cause hepatic injury and initiate an inflammatory response, which is a critical problem after liver surgery and transplantation. Xanthohumol, the major prenylated chalcone found in hops, has been discussed for its anti-inflammatory and ROS-scavenging properties, and thus, we aimed to investigate the effect of xanthohumol in a model of warm I/R liver injury. Xanthohumol was applied to BALB/c mice orally at a dose of 1 mg/g body weight for 5 days before I/R-injury was induced by clamping the vascular blood supply to the median and left lateral liver lobe for 1 h followed by a 6 h period of reperfusion. At this time, HPLC analysis revealed hepatic xanthohumol levels of approximately 2 μM, a concentration which has been shown to inhibit inflammatory effects in vitro. Assessment of hepatic HMOX1 expression, hepatic glutathione content and immunohistochemical analysis for proteins conjugated with the reactive aldehyde 4-hydroxynonenal indicated that I/R-induced oxidative stress was significantly inhibited in xanthohumol-fed compared to control mice. Histological analysis, TUNEL staining and determination of transaminase serum levels revealed no significant effects of xanthohumol on acute hepatocellular injury. However, at the same time point, pretreatment with xanthohumol almost completely blunted the I/R-induced AKT and NFκB activation and the expression of the proinflammatory genes IL-1alpha, IL-6, MCP-1 and ICAM-1, which are known to play a crucial role in the subacute phase of I/R-induced liver damage. In conclusion, these data indicate the potential of xanthohumol application to prevent adverse inflammatory responses to I/R-induced liver damage such as after surgical liver resection or transplantation.

Measurement of cell death in mammalian cells

This unit presents methods used to assess cell death in mammalian cells. The unit is divided into five sections: (1) a brief overview of cytotoxicity and pathways of cell death, (2) an improved method to measure cell death using lactate dehydrogenase (LDH) release as a marker of membrane integrity, (3) a flow cytometry method that simultaneously measures two types of cell death, oncosis and apoptosis, (4) use of nuclear morphology to assess apoptosis and oncosis, and (5) a brief discussion of the use of cytotoxicity assays to determine the mechanisms of cell death.

Lead hepatotoxicology: a study in an animal model

The increasing use of lead (Pb) for industrial purposes has resulted in the significant increase in environmental contamination of our planet especially in concern to water and food. In this study using the electron scanning microscopy (SEM), the authors showed the effects of this metal as a result of a chronic and cumulative process. As a primary method of detection of Pb in situ, SEM was chosen, coupled with a detection system Noran Voyager of basic microanalysis X-ray (SEM-XRM), with detection system energy dispersive spectrometry. Mice BALB/c was used as a study model. An animal model of inflammation was used, that consisted in the formation of a subcutaneous pocket of air. It was observed that 75% of Pb stock was captured by the liver, the main target organ in the capture of the metal, the kidney was the second organ to capture the Pb stock and the third was the spleen. It was verified that a low deposition of Pb was found in the lungs and the brain. The main results of this study showed how Pb is captured by different organs. We also demonstrated the vulnerability to inflammation of this metal.

Pathogenesis of the hyperlipidemia of Gram-negative bacterial sepsis may involve pathomorphological changes in liver sinusoidal endothelial cells

The Gram-negative bacterium Pseudomonas aeruginosa is one of the most common opportunistic pathogens, especially after liver transplantation. Pathophysiological alterations of liver sinusoidal endothelial cells (LSECs) have far-reaching repercussions on the liver and on metabolism. LSECs are perforated with fenestrations, pores that facilitate the transfer of lipoproteins and macromolecules between blood and hepatocytes. Gram-negative bacterial endotoxin (lipopolysaccharide, LPS) and the P. aeruginosa toxin, pyocyanin, have marked effects on LSECs. Initial loss of LSEC porosity (defenestration) induced by P. aeruginosa pyocyanin and LPS may confer subsequent immune tolerance to circulating bacterial antigens and toxins. This review collates the known immune responses of the liver to Gram-negative bacterial toxins, with a focus on LSECs. Hyperlipidemia is an important response to Gram-negative bacterial sepsis. The mechanisms proposed for sepsis-associated hyperlipidemia include tissue lipoprotein lipase inhibition and upregulated hepatic triglyceride production. In this review, we propose defenestration of the LSECs by bacterial toxins as an additional mechanism for the hyperlipidemia of sepsis. Given the role of LSECs in hyperlipidemia and liver allograft rejection, LSEC changes induced by P. aeruginosa toxins including LPS and pyocyanin may have significant clinical implications.

Inflammatory stress and idiosyncratic hepatotoxicity: hints from animal models

Adverse drug reactions (ADRs) present a serious human health problem. They are major contributors to hospitalization and mortality throughout the world (Lazarou et al., 1998; Pirmohamed et al., 2004). A small fraction (less than 5%) of ADRs can be classified as "idiosyncratic." Idiosyncratic ADRs (IADRs) are caused by drugs with diverse pharmacological effects and occur at various times during drug therapy. Although IADRs affect a number of organs, liver toxicity occurs frequently and is the primary focus of this review. Because of the inconsistency of clinical data and the lack of experimental animal models, how IADRs arise is largely undefined. Generation of toxic drug metabolites and induction of specific immunity are frequently cited as causes of IADRs, but definitive evidence supporting either mechanism is lacking for most drugs. Among the more recent hypotheses for causation of IADRs is that inflammatory stress induced by exogenous or endogenous inflammagens is a susceptibility factor. In this review, we give a brief overview of idiosyncratic hepatotoxicity and the inflammatory response induced by bacterial lipopolysaccharide. We discuss the inflammatory stress hypothesis and use as examples two drugs that have caused IADRs in human patients: ranitidine and diclofenac. The review focuses on experimental animal models that support the inflammatory stress hypothesis and on the mechanisms of hepatotoxic response in these models. The need for design of epidemiological studies and the potential for implementation of inflammation interaction studies in preclinical toxicity screening are also discussed briefly.

[The role of oxidative stress in alcoholic liver injury]

INTRODUCTION

Oxidative stress plays an important role in pathogenesis of alcoholic liver injury. The main source of free oxygen species is cytochrome P450-dependent monooxygenase, which can be induced by ethanol. ROLE OF CYTOCHROME P4502E1 IN ETHANOL-INDUCED OXIDATIVE STRESS: Reactive oxygen species produced by this enzyme are more important in intracellular oxidative damage compared to species derived from activated phagocytes. Free radicals lead to lipid peroxidation, enzymatic inactivation and protein oxidation. ROLE OF MITOCHONDRIA IN ALCOHOL-INDUCED OXIDATIVE STRESS. Production of mitochondrial reactive oxygen species is increased, and glutathione content is decreased in chronically ethanol-fed animals. Oxidative stress in mitochondria leads to mitochondrial DNA damage and has a dual effect on apoptosis. ROLE OF KUPFFER CELLS IN ALCOHOL-INDUCED LIVER INJURY: Chronic ethanol consumption is associated with increased release of endotoxin from gut lumen into portal circulation. Endotoxin activates Kupffer cells, which then release proinflammatory cytokines and oxidants. ROLE OF NEUTROPHILS IN ALCOHOL-INDUCED LIVER INJURY: Alcoholic liver injury leads to the accumulation of neutrophils, which release reactive oxygen species and lysosomal enzymes and contribute to hepatocyte damage and necrosis. ROLE OF NITRIC OXIDE IN ALCOHOL-INDUCED OXIDATIVE STRESS: High amounts of nitric oxide contribute to the oxidative damage, mainly by generating peroxynitrites. ROLE OF ANTIOXIDANTS IN ETHANOL-INDUCED OXIDATIVE STRESS: Chronic ethanol consumption is associated with reduced liver glutathione and alpha-tocopherol level and with reduced superoxide dismutase, catalase and glutathione peroxidase activity.

CONCLUSION

Oxidative stress in alcoholic liver disease is a consequence of increased production of oxidants and decreased antioxidant defense in the liver.

Distinct contributions of CD4+ T cell subsets in hepatic ischemia/reperfusion injury

Helper T cells are known to mediate hepatic ischemia/reperfusion (I/R) injury. However, the precise mechanisms and subsets of CD4(+) T cells that contribute to this injury are still controversial. Therefore, we sought to determine the contributions of different CD4(+) T cell subsets during hepatic I/R injury. Wild-type, OT-II, or T cell receptor (TCR)-delta-deficient mice were subjected to 90 min of partial hepatic ischemia followed by 8 h of reperfusion. Additionally, wild-type mice were pretreated with anti-CD1d, -NK1.1, or -IL-2R-alpha antibodies before I/R injury. OT-II mice had diminished liver injury compared with wild-type mice, implicating that antigen-dependent activation of CD4(+) T cells through TCRs is involved in hepatic I/R injury. TCR-delta knockout mice had decreased hepatic neutrophil accumulation, suggesting that gammadelta T cells regulate neutrophil recruitment. We found that natural killer T (NKT) cells, but not NK cells, contribute to hepatic I/R injury via CD1d-dependent activation of their TCRs, as depletion of NKT cells by anti-CD1d antibody or depletion of both NKT cells and NK cells by anti-NK1.1 attenuated liver injury. Although regulatory T cells (Treg) are known to suppress T cell-dependent inflammation, depletion of Treg cells had little effect on hepatic I/R injury. The data suggest that antigen-dependent activation of CD4(+) T cells contributes to hepatic I/R injury. Among the subsets of CD4(+) T cells, it appears that gammadelta T cells contribute to neutrophil recruitment and that NKT cells directly injure the liver. In contrast, NK cells and Treg have little effects on hepatic I/R injury.

Histological and biochemical alterations in early-stage lobar ischemia-reperfusion in rat liver

AIM: To investigate the structural and biochemical changes in the early stage of reperfusion in the rat livers exposed to lobar ischemia-reperfusion (IR).

METHODS: The median and left lobes of the liver were subjected to 60 min ischemia followed by 5, 10, 30, 45, 60 and 120 min reperfusion. Blood samples were taken at different time intervals to test enzyme activities and biochemical alterations induced by reperfusion. At the end of each reperfusion period, the animals were killed by euthanasia and tissue samples were taken for histological examination and immunohistochemistry.

RESULTS: Cell vacuolation, bleb formation and focal hepatitis were the most important changes occur during ischemia. While some changes including bleb formation were removed during reperfusion, other alterations including portal hepatitis, inflammation and the induction of apoptosis were seen during this stage. The occurrence of apoptosis, as demonstrated by apoptotic cells and bodies, was the most important histological change during reperfusion. The severity of apoptosis was dependent on the time of reperfusion, and by increasing the time of reperfusion, the numbers of apoptotic bodies was significantly enhanced. The amounts of lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, creatinine and urea were significantly increased in serum obtained from animals exposed to hepatic IR.

CONCLUSION: Inflammation and subsequent apoptotic cell death were the most important changes in early-stage hepatic reperfusion injury, and the number of apoptotic bodies increased with time of reperfusion.

Failure of P-selectin blockade alone to protect the liver from ischemia-reperfusion injury in the isolated blood-perfused rat liver

AIM: To determine if blockade of P-selectin in the isolated blood-perfused cold ex vivo rat liver model protects the liver from ischemia-reperfusion injury.

METHODS: The effect of P-selectin blockade was assessed by employing an isolated blood-perfused cold ex vivo rat liver with or without P-selectin antibody treatment before and after 6 h of cold storage in University of Wisconsin solution.

RESULTS: In our isolated blood-perfused rat liver model, pre-treatment with P-selectin antibody failed to protect the liver from ischemia-reperfusion injury, as judged by the elevated aspartate aminotransferase activity. In addition, P-selectin antibody treatment did not significantly reduced hepatic polymorphonuclear leukocyte accumulation after 120 min of perfusion. Histological evaluation of liver sections obtained at 120 min of perfusion showed significant oncotic necrosis in liver sections of both ischemic control and P-selectin antibody-treated groups. However, total bile production after 120 min of perfusion was significantly greater in P-selectin antibody-treated livers, compared to control livers. No significant difference in P-selectin and ICAM-1 mRNAs and proteins, GSH, GSSG, and nuclear NF-κB was found between control and P-selectin antibody-treated livers.

CONCLUSION: In conclusion, we have shown that blockade of P-selectin alone failed to reduced polymorphonuclear leukocyte accumulation in the liver and protect hepatocytes from ischemia-reperfusion injury in the isolated blood-perfused cold-ex vivo rat liver model.

Identification and preliminary validation of novel biomarkers of acute hepatic ischaemia/reperfusion injury using dual-platform proteomic/degradomic approaches

Hepatic ischaemia/reperfusion (I/R), a major cause of liver damage associated with multiple trauma, haemorrhagic and septic shock, and liver transplantation, contributes significantly to multiple organ failure. Development of novel sensitive biomarkers that detect early stages of liver damage is vital for effective management and treatment of ischaemic liver injury. By using high-throughput immunoblotting and cation-anion exchange chromatography/reversed-phase liquid chromatography-tandem mass-spectrometry, we identified several hepatic proteins, including argininosuccinate synthase (ASS) and estrogen sulfotransferase (EST-1), which were degraded in the liver and rapidly released into circulation during I/R injury. ASS accumulated in serum within 10 min, reached a steady state at 30 min, and persisted up until 3 h after reperfusion following 30 min of total hepatic ischaemia. EST-1 appeared rapidly in blood and attained maximum within 1 hour followed by a decline at 3 h of reperfusion. No ASS or EST-1 protein was detected in serum of control or sham operated rats. ASS and EST-1 exhibited greater sensitivity and specificity toward I/R liver injury as compared with alanine aminotransferase (ALT), an established marker of hepatocellular necrosis. In contrast, serum ASS and EST-1 were undetectable in rats with chronic alcoholic liver disease, while the levels of ALT protein were significantly increased. In addition, ASS, but not EST-1 or ALT accumulated in blood only 6 h after treatment with hepatotoxic combination of lipopolysaccharide and D-galactosamine. These data demonstrate the utility of ASS and EST-1 as novel sensitive and specific biomarkers of acute liver ischaemic injury for prospective clinical studies.

Molecular mediators of liver ischemia and reperfusion injury: a brief review

Ischemia and reperfusion injury is a dynamic process that involves multiple organ systems in various clinical states including transplantation, trauma, and surgery. Research into this field has identified key molecular and signaling players that mediate, modulate, or augment cellular, tissue, and organ injury during this disease process. Further elucidation of the molecular mechanisms should provide the rationale to identify much-needed novel therapeutic options to prevent or ameliorate organ damage due to ischemia and reperfusion in clinics.

Endogenous A1 adenosine receptors protect against hepatic ischemia reperfusion injury in mice

Hepatic ischemia reperfusion (IR) injury is a major clinical problem during the perioperative period and occurs frequently after major hepatic resection or liver transplantation. Exogenous and endogenous A(1) adenosine receptor (A(1)AR) activation protects against renal IR injury. In this study, we questioned whether exogenous and endogenous A(1)AR activation protects against hepatic IR injury in vivo. A(1)AR wild-type (WT) or knockout mice were subjected to 60 minutes of partial hepatic IR. Some animals were treated with a selective A(1)AR agonist, 2-chloro-N(6)-cyclopentyladenosine (CCPA; 0.1 mg/kg), or a selective A(1)AR antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 0.4 mg/kg), 15 minutes before hepatic ischemia. Twenty-four hours after hepatic IR, the A(1) knockout mice and DPCPX-treated A(1) wild-type (A(1)WT) mice developed significantly worse liver injury (alanine aminotransferase, liver necrosis, neutrophil infiltration, and apoptosis) compared to A(1)AR WT mice. However, the selective A(1)AR agonist CCPA failed to protect against hepatic IR injury in A(1)WT mice. Our results show that the endogenous A(1)ARs protect against hepatic IR injury in vivo by primarily reducing apoptosis and necrosis with subsequent reductions in proinflammatory neutrophil infiltration. However, in contrast to the kidneys, in which exogenous A(1)AR activation protected against IR injury, exogenous A(1)AR activation failed to protect against liver injury after IR. We conclude that endogenous A(1)AR activation prevents worsened murine liver IR injury primarily by reducing necrotic and apoptotic cell death. Harnessing the mechanisms of cytoprotection with endogenous A(1)AR activation may lead to new therapies for perioperative hepatic IR injury.

Analysis of chemokines and reactive oxygen species formation by rat and human neutrophils induced by microcystin-LA, -YR and -LR

Microcystins (MC), a family of heptapeptide toxins produced by some genera of Cyanobacteria, have potent hepatotoxicity and tumor-promoting activity. Leukocyte infiltration in the liver was observed in MC-induced acute intoxication. Although the mechanisms of hepatotoxicity are still unclear, neutrophil infiltration in the liver may play an important role in triggering toxic injury and tumor development. The present study reports the effects of MC-LA, MC-YR and MC-LR (1 and 1000 nM) on human and rat neutrophils functions in vitro. Cell viability, DNA fragmentation, mitochondrial membrane depolarization and intracellular reactive oxygen species (ROS) levels were measured by flow cytometry. Extracellular ROS content was measured by lucigenin-amplified chemiluminescence, and cytokines were determined by ELISA. We found that these MC increased interleukin-8 (IL-8), cytokine-induced neutrophil chemoattractant-2alphabeta (CINC-2alphabeta) and extracellular ROS levels in human and rat neutrophils. Apart from neutrophil presence during the inflammatory process of MC-induced injury, our results suggest that hepatic neutrophil accumulation is further increased by MC-induced neutrophil-derived chemokine.

Remote ischemic preconditioning: a novel protective method from ischemia reperfusion injury--a review

BACKGROUND

Restoration of blood supply to an organ after a critical period of ischemia results in parenchymal injury and dysfunction of the organ referred to as reperfusion injury. Ischemia reperfusion injury is often seen in organ transplants, major organ resections and in shock. Ischemic preconditioning (IPC) is an adaptational response of briefly ischemic tissues which serves to protect against subsequent prolonged ischemic insults and reperfusion injury. Ischemic preconditioning can be mechanical or pharmacological. Direct mechanical preconditioning in which the target organ is exposed to brief ischemia prior to prolonged ischemia has the benefit of reducing ischemia-reperfusion injury (IRI) but its main disadvantage is trauma to major vessels and stress to the target organ. Remote (inter organ) preconditioning is a recent observation in which brief ischemia of one organ has been shown to confer protection on distant organs without direct stress to the organ.

AIM

To discuss the evidence for remote IPC (RIPC), underlying mechanisms and possible clinical applications of RIPC. METHODS OF SEARCH: A Pubmed search with the keywords "ischemic preconditioning," "remote preconditioning," "remote ischemic preconditioning," and "ischemia reperfusion" was done. All articles on remote preconditioning up to September 2006 have been reviewed. Relevant reference articles from within these have been selected for further discussion.

RESULTS

Experimental studies have demonstrated that the heart, liver, lung, intestine, brain, kidney and limbs are capable of producing remote preconditioning when subjected to brief IR. Remote intra-organ preconditioning was first described in the heart where brief ischemia in one territory led to protection in other areas. Translation of RIPC to clinical application has been demonstrated by the use of brief forearm ischemia in preconditioning the heart prior to coronary bypass and in reducing endothelial dysfunction of the contra lateral limb. Recently protection of the heart has been demonstrated by remote hind limb preconditioning in children who underwent surgery on cardiopulmonary bypass for congenital heart disease. The RIPC stimulus presumably induces release of biochemical messengers which act either by the bloodstream or by the neurogenic pathway resulting in reduced oxidative stress and preservation of mitochondrial function. Studies have demonstrated endothelial NO, Free radicals, Kinases, Opioids, Catecholamines and K(ATP) channels as the candidate mechanism in remote preconditioning. Experiments have shown suppression of proinflammatory genes, expression of antioxidant genes and modulation of gene expression by RIPC as a novel method of IRI injury prevention.

CONCLUSION

There is strong evidence to support RIPC. The underlying mechanisms and pathways need further clarification. The effective use of RIPC needs to be investigated in clinical settings.

Aggravation of different types of experimental colitis by depletion or adhesion blockade of neutrophils

BACKGROUND & AIMS

Neutrophils are generally thought to play an important proinflammatory role in the pathogenesis of inflammatory bowel disease. The objective of this study was to evaluate whether blocking the invasion of neutrophils by anti-L-selectin monoclonal antibodies modulates chemically induced colitis and how this modulation is accomplished.

METHODS

Trinitrobenzene sulfonic acid/dinitrobenzene sulfonic acid (TNBS/DNBS)-induced colitis was studied in rats on treatment with anti-L-selectin monoclonal antibodies (mAb) or antineutrophil antiserum. Different anti-L-selectin mAb, either blocking or nonblocking, as well as F(ab)(2) fragments were evaluated. Additionally, leukocyte migration was examined using intravital microscopy. Furthermore, the effect of neutrophil depletion in rat TNBS-induced colitis was studied either prior to or after colitis induction as well as murine CD4(+)CD45RB(high) transfer colitis. Finally, bacterial translocation during DNBS-induced colitis was studied in neutrophil-depleted and control rats.

RESULTS

Anti-L-selectin mAb treatment resulted in increased mortality and bowel inflammation as well as hemorrhagic eye secretion. No clear difference was found between blocking and nonblocking mAb or F(ab)(2) fragments. For all investigated antibodies/fragments, either complete blockade of leukocyte invasion or marked neutrophil depletion was found. Accordingly, neutrophil depletion by antiserum resulted in aggravation of rat DNBS-induced colitis as well as murine transfer colitis.

CONCLUSIONS

Adhesion blockade or neutrophil depletion aggravates rat TNBS/DNBS-induced colitis together with extraintestinal manifestations of the eyes. Therefore, neutrophils appear to have an important role in mucosal repair processes. Importantly, adhesion blockade as a therapeutic concept can be detrimental in inflammatory bowel disease.

Endocannabinoids and cannabinoid receptors in ischaemia-reperfusion injury and preconditioning

Ischaemia-reperfusion (I/R) is a pivotal mechanism of organ injury during stroke, myocardial infarction, organ transplantation and vascular surgeries. Ischaemic preconditioning (IPC) is a potent endogenous form of tissue protection against I/R injury. On the one hand, endocannabinoids have been implicated in the protective effects of IPC through cannabinoid CB1/CB2 receptor-dependent and -independent mechanisms. However, there is evidence suggesting that endocannabinoids are overproduced during various forms of I/R, such as myocardial infarction or whole body I/R associated with circulatory shock, and may contribute to the cardiovascular depressive state associated with these pathologies. Previous studies using synthetic CB1 receptor agonists or knockout mice demonstrated CB1 receptor-dependent protection against cerebral I/R injury in various animal models. In contrast, several follow-up reports have shown protection afforded by CB1 receptor antagonists, but not agonists. Excitedly, emerging studies using potent CB2 receptor agonists and/or knockout mice have provided compelling evidence that CB2 receptor activation is protective against myocardial, cerebral and hepatic I/R injuries by decreasing the endothelial cell activation/inflammatory response (for example, expression of adhesion molecules, secretion of chemokines, and so on), and by attenuating the leukocyte chemotaxis, rolling, adhesion to endothelium, activation and transendothelial migration, and interrelated oxidative/nitrosative damage. This review is aimed to discuss the role of endocannabinoids and CB receptors in various forms of I/R injury (myocardial, cerebral, hepatic and circulatory shock) and preconditioning, and to delineate the evidence supporting the therapeutic utility of selective CB2 receptor agonists, which are devoid of psychoactive effects, as a promising new approach to limit I/R-induced tissue damage.

Acute oral toxicity of colchicine in rats: effects of gender, vehicle matrix and pre-exposure to lipopolysaccharide

The oral toxicity of a single administration by gavage (10, 20 or 30 mg kg(-1) body weight) of colchicine (COL) was determined in young, mature male and female Sprague-Dawley rats. The effect of COL was evaluated in the presence or absence of additional treatment variables that included vehicle and lipopolysaccharide (LPS) pre-exposure. The vehicle for COL was either Half and Half cream (H & H) or saline, and each group included pretreatment with either saline or a low, minimally toxic dose (83 microg kg(-1) body weight) of LPS. Colchicine toxicity in both male and female age-matched rats was characterized by progressively more severe dose-related clinical signs of toxicity. These included mortality, decreased body weight and feed intake during the first several days after dosing, with recovery thereafter in surviving animals. There were differences in the severity of the toxic response to COL between male and female rats. The most notable sex-related difference was in COL lethality. Female rats were two times more susceptible to the lethal effects of COL than male rats. Saline or H & H delivery vehicles did not result in any apparent qualitative or quantitative differences in COL toxicity. LPS pretreatment significantly potentiated COL lethality in both males and females, although the potentiation in males was greater than in females. LPS pretreatment modestly increased the COL induced anorexic effect in surviving males, but not in surviving female animals. LPS did not appear to modulate either the body weights or clinical signs of COL induced toxicity in surviving males or females.

Cannabinoid-2 receptor agonist HU-308 protects against hepatic ischemia/reperfusion injury by attenuating oxidative stress, inflammatory response, and apoptosis

In this study, we have investigated the role of the cannabinoid CB(2) (CB(2)) receptor in an in vivo mouse model of hepatic ischemia/reperfusion (I/R) injury. In addition, we have assessed the role of the CB(2) receptor in TNF-alpha-induced ICAM-1 and VCAM-1 expression in human liver sinusoidal endothelial cells (HLSECs) and in the adhesion of human neutrophils to HLSECs in vitro. The potent CB(2) receptor agonist HU-308, given prior to the induction of I/R, significantly attenuated the extent of liver damage (measured by serum alanine aminotransferase and lactate dehydrogenase) and decreased serum and tissue TNF-alpha, MIP-1alpha, and MIP-2 levels, tissue lipid peroxidation, neutrophil infiltration, DNA fragmentation, and caspase 3 activity. The protective effect of HU-308 against liver damage was also preserved when given right after the ischemic episode. HU-308 also attenuated the TNF-alpha-induced ICAM-1 and VCAM-1 expression in HLSECs, which expressed CB(2) receptors, and the adhesion of human neutrophils to HLSECs in vitro. These findings suggest that selective CB(2) receptor agonists may represent a novel, protective strategy against I/R injury by attenuating oxidative stress, inflammatory response, and apoptosis.

Neutrophil interaction with the hemostatic system contributes to liver injury in rats cotreated with lipopolysaccharide and ranitidine

Cotreatment of rats with nontoxic doses of ranitidine (RAN) and lipopolysaccharide (LPS) causes liver injury, and this drug-inflammation interaction might be a model for idiosyncratic adverse drug responses in humans. Both polymorphonuclear neutrophils (PMNs) and the hemostatic system have been shown to be important in the injury. We tested the hypothesis that PMNs cause liver injury by interacting with the hemostatic system and producing subsequent hypoxia. In rats cotreated with LPS/RAN, PMN depletion by anti-PMN serum reduced fibrin deposition and hypoxia in the liver. PMN depletion also reduced the plasma concentration of active plasminogen activator inhibitor-1 (PAI-1), a major down-regulator of the fibrinolytic system. This suggests that PMNs promote fibrin deposition by increasing PAI-1 concentration. PMNs were activated in the livers of LPS/RAN-cotreated rats as evidenced by increased staining for hypochlorous acid-modified proteins generated by the myeloperoxidase-hydrogen peroxide-chloride system of activated phagocytes. Antiserum against the PMN adhesion molecule CD18 protected against LPS/RAN-induced liver injury. Because CD18 is important for PMN transmigration and activation, these results suggest that PMN activation is required for the liver injury. Furthermore, anti-CD18 serum reduced biomarkers of hemostasis and hypoxia, suggesting the necessity for PMN activation in the interaction between PMNs and the hemostatic system/hypoxia. Liver injury, liver fibrin, and plasma PAI-1 concentration were also reduced by eglin C, an inhibitor of proteases released by activated PMNs. In summary, PMNs are activated in LPS/RAN-cotreated rats and participate in the liver injury in part by contributing to hemostasis and hypoxia.

Cannabinoid-2 receptor mediates protection against hepatic ischemia/reperfusion injury

Hepatic ischemia-reperfusion (I/R) injury continues to be a fatal complication that can follow liver surgery or transplantation. We have investigated the involvement of the endocannabinoid system in hepatic I/R injury using an in vivo mouse model. Here we report that I/R triggers several-fold increases in the hepatic levels of the endocannabinoids anandamide and 2-arachidonoylglycerol, which originate from hepatocytes, Kupffer, and endothelial cells. The I/R-induced increased tissue endocannabinoid levels positively correlate with the degree of hepatic damage and serum TNF-alpha, MIP-1alpha, and MIP-2 levels. Furthermore, a brief exposure of hepatocytes to various oxidants (H2O2 and peroxynitrite) or inflammatory stimuli (endotoxin and TNF-alpha) also increases endocannabinoid levels. Activation of CB2 cannabinoid receptors by JWH133 protects against I/R damage by decreasing inflammatory cell infiltration, tissue and serum TNF-alpha, MIP-1alpha and MIP-2 levels, tissue lipid peroxidation, and expression of adhesion molecule ICAM-1 in vivo. JWH133 also attenuates the TNF-alpha-induced ICAM-1 and VCAM-1 expression in human liver sinusoidal endothelial cells (HLSECs) and the adhesion of human neutrophils to HLSECs in vitro. Consistent with the protective role of CB2 receptor activation, CB2-/- mice develop increased I/R-induced tissue damage and proinflammatory phenotype. These findings suggest that oxidative/nitrosative stress and inflammatory stimuli may trigger endocannabinoid production, and indicate that targeting CB2 cannabinoid receptors may represent a novel protective strategy against I/R injury. We also demonstrate that CB2-/- mice have a normal hemodynamic profile.

Investigations toward enhanced understanding of hepatic idiosyncratic drug reactions

Idiosyncratic drug reactions (IDRs) of a hepatic origin are a major health concern and a notoriously difficult challenge for the pharmaceutical industry. These types of adverse events are rare, with a typical occurrence of 1 in 100 to 1 in 100,000 patients. Typical adverse outcomes are most likely statistically impossible to predict in traditional preclinical safety studies or clinical trials. Unfortunately, these reactions can pose a significant risk to the public health, resulting in devastating consequences such as irreversible liver injury, liver transplantation and fatality. This review provides many examples of experimental efforts that are underway for a better understanding of molecular events that may be responsible for IDRs. A list of existing hypotheses for IDRs is also provided, each with current literature examples or supporting evidence. The possibilities for developing suitable animal models for the prediction and characterisation of IDRs are elaborated, especially for a drug-inflammation interaction rat model of hepatic IDR. The need for predictive biomarkers of IDR is addressed, with the exploration of some possible candidates. Finally, the use of primary human hepatocyte culture systems is explored as an in vitro system, with application for providing an increased mechanistic knowledge of IDR. Several examples of informative studies on the nature of IDRs that employ toxicogenomic and proteomic technologies are summarised.

Influence of indole acetic acid on antioxidant levels and enzyme activities of glucose metabolism in rat liver

Indole acetic acid (IAA) is an auxin and can be synthesized in animals. This compound is metabolized in vitro by peroxidase, producing reactive oxygen species. The toxic effect of indole acetic acid in leukocytes is associated with peroxidase activities and these processes have been implicated in activation of glucose and glutamine metabolism. However, studies in vitro have shown that IAA, in absence of peroxidase, is an antioxidant almost as high in potency as those of other indolic compounds. The purpose of this study was to investigate the possible involvement of a toxic effect of indole acetic acid in the liver, as evidenced by oxidative stress and enzyme activities of the glucose pathway. The animals received IAA by subcutaneous or gavage administration in a phosphate buffered saline (the control group received only the phosphate buffered saline). The other groups received IAA at concentrations of 1 mg, 18 mg and 40 mg per kg of body mass per day. Treatments with 18 mg and 40 mg IAA decreased the activity of catalase by both subcutaneous (30% and 26%) or gavage administration (19% and 28%), respectively. A similar effect was observed on the activity of glutathione peroxidase of animals exposed to 18 mg and 40 mg IAA: A decrease of 34% and 29%, respectively, for subcutaneous administration and a decrease of 29% and 25%, respectively, for gavage administration. However, in neither source of administration did the acid alter superoxide dismutase, glutathione reductase and myeloperoxidase activities. Another alteration was observed in respect of reduced glutathione content in this organ. The lipid peroxidation level showed a significant decrease with subcutaneous (30%, 29% and 24%) and gavage administration (25%, 26% and 24%) using 1 mg, 18 mg and 40 mg of IAA, respectively compared with the control. The reduced glutathione content and catalase activity in the plasma were not altered by either of the two methods of administration. In addition to these findings, after subcutaneous or gavage administration of IAA, the activities of hepatic enzymes of glucose metabolism were not affected (glucokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase and citrate synthase). Evidence is presented herein that IAA did not have a pro-oxidant effect in the liver as deduced from a reduction of catalase and glutathione peroxidase activities, a decrease of lipid peroxidation content and no alteration of the pool of reduced glutathione. The effects of IAA were independent of the way of administration.

Mechanisms of Acute Liver Failure

Acute liver failure is characterized by the sudden onset of liver failure in a patient without evidence of chronic liver disease. This definition is important, as it differentiates patients with acute liver failure from patients who suffer from liver failure owing to end-stage chronic liver disease.

x-Irradiation in Rat Liver: Consequent Upregulation of Hepcidin and Downregulation of Hemojuvelin and Ferroportin-1 Gene Expression

PURPOSE

To prospectively analyze hepcidin, hemojuvelin, and ferroportin-1 expression after x-irradiation of rat liver and isolated rat hepatocytes.

MATERIALS AND METHODS

The treatment of the rats and this study were approved by the local committee and the public authority on animal welfare. Rat livers in vivo and isolated rat hepatocytes in vitro were irradiated. The total number of rats in this study was 43. RNA extracted from livers (1, 3, 6, 12, 24, and 48 hours after irradiation) and from hepatocytes (1, 3, 6, 12, and 24 hours after irradiation) was analyzed with real-time polymerase chain reaction and Northern blot. Cytokines and prohepcidin in serum of irradiated rats were quantitatively detected with enzyme-linked immunosorbent assay. Sham-irradiated animals served as controls in all experiments. Differences between sham-irradiated and irradiated data groups were tested with analysis of variance and Dunnett post hoc test.

RESULTS

In vivo, a significant radiation-induced increase of hepcidin (P=.034), interleukin (IL) 1beta (P=.008), IL-6 (P<.011), and tumor necrosis factor alpha (TNF-alpha) (P=.047) expression could be detected within the first 48 hours after irradiation. Expression of hemojuvelin (P=.008) and ferroportin-1 (P=.002) was significantly decreased. Serum iron levels were decreased because of irradiation (P<.058); prohepcidin serum levels were increased (P=.05). In rat hepatocytes in vitro, hepcidin RNA levels were significantly downregulated after irradiation (P<.001). Incubation of irradiated hepatocytes with IL-1beta, IL-6, or TNF-alpha led to upregulation of hepcidin expression in vitro up to 6 hours after irradiation, with subsequent significant downregulation for incubation with IL-1beta (P<.001). Hemojuvelin expression behaved in a way opposite to that of hepcidin.

CONCLUSION

x-Irradiation of the liver induced changes of hepcidin gene expression that are probably induced by acute phase mediators produced within the liver itself.