D-galactosamine-induced mouse hepatic apoptosis: possible involvement with tumor necrosis factor, but not with caspase-3 activity

Pyruvate Kinase M2: A Novel Biomarker for the Early Detection of Acute Kidney Injury

The identification of biomarkers for the early detection of acute kidney injury (AKI) is clinically important. Acute kidney injury (AKI) in critically ill patients is closely associated with increased morbidity and mortality. Conventional biomarkers, such as serum creatinine (SCr) and blood urea nitrogen (BUN), are frequently used to diagnose AKI. However, these biomarkers increase only after significant structural damage has occurred. Recent efforts have focused on identification and validation of new noninvasive biomarkers for the early detection of AKI, prior to extensive structural damage. Furthermore, AKI biomarkers can provide valuable insight into the molecular mechanisms of this complex and heterogeneous disease. Our previous study suggested that pyruvate kinase M2 (PKM2), which is excreted in the urine, is a sensitive biomarker for nephrotoxicity. To appropriately and optimally utilize PKM2 as a biomarker for AKI requires its complete characterization. This review highlights the major studies that have addressed the diagnostic and prognostic predictive power of biomarkers for AKI and assesses the potential usage of PKM2 as an early biomarker for AKI. We summarize the current state of knowledge regarding the role of biomarkers and the molecular and cellular mechanisms of AKI. This review will elucidate the biological basis of specific biomarkers that will contribute to improving the early detection and diagnosis of AKI.

Proline protects liver from D-galactosamine hepatitis by activating the IL-6/STAT3 survival signaling pathway

The oral administration of proline, one of the non-essential amino acids, has been shown to effectively protect the liver from D-galactosamine (GalN)-induced liver injury and to improve the survival rate. The aim of this study was to investigate the mechanism of this protective action of proline. We paid particular attention to the effect of proline on inflammatory activation, regenerative response, and the associated signal transduction in the liver. Male Fischer rats received intraperitoneal injections of GalN (1.4 g/kg) with or without the oral administration of proline (2 g/kg) 1 h before GalN treatment. Liver pathology, plasma indices of inflammation, and the level of proliferative marker in the liver were monitored. The hepatic activation of interleukin-6 (IL-6)/signal transducer and activator of transcription (STAT)-3 pathway, which is downstream of tumor necrosis factor (TNF)-α/nuclear factor-κB, was also studied. GalN induced massive inflammatory expansion in the liver, leading to a high death rate (60 %) more than 72 h after the treatment. Proline administration significantly suppressed inflammatory infiltration in the live after 48 h, which was accompanied by depletion of plasma TNF-α, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase. The mRNA expression of histone H3, a marker of proliferation, was significantly upregulated in the liver of proline-treated animals. Furthermore, IL-6/STAT-3 pathway, an anti-inflammatory and regenerative signaling pathway, was strongly activated prior to these observations, with the upregulated expression of downstream genes. These results suggest that the tissue-protective mechanism of proline involves the early activation of IL-6/STAT-3 pathway in the liver, with subsequent activation of the regenerative response and suppression of massive inflammatory activation.

Health-promoting effects of green tea

Green tea is manufactured from the leaves of the plant Camellia sinensis Theaceae and has been regarded to possess anti-cancer, anti-obesity, anti-atherosclerotic, anti-diabetic, anti-bacterial, and anti-viral effects. Many of the beneficial effects of green tea are related to the activities of (-)-epigallocatechin gallate (EGCG), a major component of green tea catechins. For about 20 years, we have engaged in studies to reveal the biological activities and action mechanisms of green tea and EGCG. This review summarizes several lines of evidence to indicate the health-promoting properties of green tea mainly based on our own experimental findings.

Aqueous garlic extract attenuates hepatitis and oxidative stress induced by galactosamine/lipoploysaccharide in rats

Injection of D-galactosamine and lipopolysaccharide (DGaIN/LPS) is useful as an experimental model of acute hepatic damage. Juvenile rats were used for investigation. The hepatoprotective activity of aqueous garlic (Allium sativum) extract (AGE) at a dose of 300 mg/kg body weight for 14 days, intraperitoneal (i.p.) prior to the induction of DGalN/LPS, was investigated against DGalN/LPS-induced hepatitis in rats. DGalN/LPS (300 mg/kg body weight/30 microg/kg body weight, i.p.), induced hepatic damage that was manifested by a significant increase in the activities of marker enzymes [alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and gamma glutamyl transferase (gamma GT)], bilirubin, lipid peroxides (LPO), tumor necrosis factor (TNF-alpha) and myeloperoxidase (MPO) activity level in serum. Also, the lipid profile in serum and liver homogenate including total cholesterol, triglycerides, free fatty acids and phospholipids were significantly deteriorated. The antioxidant enzyme activities (superoxide dismutase, SOD; reduced glutathione, GSH; catalase, CAT and glutathione peroxidase, GPX) in liver homogenate were significantly decreased in the DGalN/LPS. Pretreatment of rats with AGE reversed these altered parameters near to normal control values. Results of this study revealed that AGE could afford a significant protection in the alleviation of DGalN/LPS-induced hepatic damage.

Galactosamine-induced hepatotoxic effect and hepatoprotective role of a protein isolated from the herb Cajanus indicus L in vivo

dd(+)-Galactosamine is a well-known experimental hepatotoxin. The present study was conducted to determine the protective role of a 43-kD protein isolated from the leaves of the herb Cajanus indicus L against D(+)-galactosamine (GalN) induced liver damage in mice. Both preventive and curative effects of the protein have been investigated in the study. The protein was administered intraperitoneally at a dose of 2 mg/kg body weight for 4 days before and after GalN intoxication at a dose of 800 mg/kg body weight for 3 days. The increased activities of serum marker enzymes, alanine aminotransferase, and alkaline phosphatase because of GalN administration, were significantly reduced by the protein treatment. The protein also normalized the altered activities of antioxidant enzymes superoxide dismutase, catalase, glutathione reductase, and glutathione-S-transferase as well as the levels of cellular metabolites, reduced glutathione, glutathione disulfide, and total thiols. In addition, the enhanced hepatic lipid peroxidation because of GalN intoxication was also effectively inhibited by the protein treatment. Results suggest that GalN caused hepatic damages via oxidative insult and that the protein provided protection through its antioxidant mechanism.

Green tea with a high catechin content suppresses inflammatory cytokine expression in the galactosamine-injured rat liver

Galactosamine is known to induce hepatic injury in rats and the galactosamine-induced hepatitis is believed to be similar to viral hepatitis both morphologically and functionally. In the present study, we examined how drinking green tea affects the gene expression of inflammatory cytokines which may be up-regulated in galactosamine-induced hepatitis. As has been reported, galactosamine caused hepatic injury in rats as evidenced by an increase in serum transaminase activities and histological observations of the liver. The results of the reverse transcription and polymerase chain reaction indicated an increased gene expression of inflammatory cytokines, tumor necrosis factor-alpha and interleukin-1beta, in the injured liver and the enzyme linked immunoassay showed an increase in the serum levels of these cytokines. Oral administration of green tea rich in catechins (Healthya green tea) restored these biomarkers in the galacotsamine-treated rats to near the control levels. These results suggest that the drinking of green tea with a high catechin content may help to prevent and/or attenuate the development of a certain type of hepatitis.

Antioxidant activity of medicinal herb Rhodococcum vitis-idaea on galactosamine-induced liver injury in rats

Aim of the study was to evaluate in vivo antioxidant action of medicinal herb Rhodococcum vitis-idaea (Rh.v) on galactosamine (GalN)-induced rat liver toxicity. The results showed that the hepatotoxicity and oxidative stress induced by GalN (700 mg/kg, s.c.) after 24 h evidenced by an increase in serum alanine aminotransferase and glutathione (GSH) S-transferase activities, and lipid peroxidation in liver homogenate were significantly inhibited, when 10 times diluted Rh.v. extract (5 ml/kg, i.p.) was given to rats 12 and 1 h before GalN treatment demonstrating that the extract of Rh.v is a potent antioxidant and protective against GalN-induced hepatotoxicity. The main antioxidant compound of the herb water extract used in the experiment was determined as arbutin, which possess 8% of dry weight of the herb. The electron spin resonance (ESR) spectrometer analysis revealed that the arbutin isolated from Rh.v exhibited strong superoxide and hydroxyl radical scavenging ability.

Induction of apoptosis by 2,3,7,8-tetrachlorodibenzo-p-dioxin following endotoxin exposure

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent and persistent environmental toxin that induces hepatotoxicity and increases endotoxin-induced liver injury. The objective of this study was to evaluate whether TCDD could modulate apoptosis and cytokine-controlled apoptotic signaling pathways following lipopolysaccharide (LPS) exposure in female B6C3F1 mice. The effects of TCDD treatment were most dramatic late in the time course (10-14 days posttreatment). Serum enzyme activities were elevated at day 10 (100 microg TCDD/40 microg LPS treatment) and day 14 (100 microg TCDD/saline treatment), indicating peak liver damage occurred at those times. Histological examination of perfused livers showed an increase in apoptotic cells at day 14 in animals treated with 10 microg TCDD. Caspase-1 activity was suppressed at 14 days in mice treated with 100 microg TCDD/40 microg LPS and 100 microg TCDD/4 microg LPS compared to the respective corn oil (CO)/LPS-treated controls. Caspase-3 activity was suppressed at 14 days in 100 microg TCDD/saline-100 microg TCDD/40 microg LPS- and 100 microg TCDD/4 microg LPS-treated mice compared to respective CO/saline- or CO/LPS-treated control mice. At 40 microg LPS, caspase activity was stimulated in TCDD (100 microg)-exposed mice at 3 and 7 days and then suppressed at 10 and 14 days. Western blot analysis, electrophoretic mobility shift assay, and ELISA did not show any effect by TCDD (100 microg) on IkappaB-beta and IkappaB-alpha protein expression or on DNA binding activity of the nuclear NFkappaB protein. These data indicate that TCDD induces apoptosis 14 days posttreatment; however, we found no evidence of suppression of the antiapoptotic transcription factor NFkappaB.

Evaluation of oxidative stress during apoptosis and necrosis caused by D-galactosamine in rat liver

Eighteen and twenty-four hours after intraperitoneal administration of D-galactosamine (1g/kg body weight) to rats, the activity of caspase-3-like protease in the liver increased significantly compared with that in the control group given saline. Histological examinations including the in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method found apoptotic hepatocytes 18 hr after the administration of D-galactosamine. Caspase-3 activity was barely detectable in the plasma of control rats, but increased significantly 24 hr after drug administration along with a dramatic increase in glutamate-oxaloacetate transaminase (GOT). These results indicated that D-galactosamine causes apoptosis in the liver by activating caspase-3, which is released to the plasma by secondary necrosis. The concentration of lipid hydroperoxides in the liver increased significantly 24 hr after D-galactosamine administration. In contrast, the concentration of vitamin C in the liver decreased significantly 18 and 24 hr after D-galactosamine administration. These results suggest that D-galactosamine induces severe oxidative stress in the liver, leading to extensive necrosis.

The role of cytokines in liver failure and regeneration: potential new molecular therapies

The liver is a unique organ, and first in line, the hepatocytes encounter the potential to proliferate during cell mass loss. This phenomenon is tightly controlled and resembles in some way the embryonal co-inhabitant cell lineage of the liver, the embryonic hematopoietic system. Interestingly, both the liver and hematopoietic cell proliferation and growth are controlled by various growth factors and cytokines. IL-6 and its signaling cascade inside the cells through STAT3 are both significantly important for liver regeneration as well as for hematopoietic cell proliferation. The process of liver regeneration is very complex and is dependent on the etiology and extent of liver damage and the genetic background. In this review we will initially describe the clinical relevant condition, portraying a number of available animal models with an emphasis on the relevance of each one to the human condition of fulminant hepatic failure (FHF). The discussion will then be focused on the role of cytokines in liver failure and regeneration, and suggest potential new therapeutic modalities for FHF. The recent findings on the role of IL-6 in liver regeneration and the activity of the designer IL-6/sIL-6R fusion protein, hyper-IL-6, in particular, suggest that this molecule could significantly enhance liver regeneration in humans, and as such could be a useful treatment for FHF in patients.

Hyper-IL-6 gene therapy reverses fulminant hepatic failure

Fulminant hepatic failure is a catastrophic condition caused by massive hepatocellular apoptosis and necrosis. Inhibition of hepatocyte apoptosis and the enhancement of the endogenous potential for liver regeneration could potentially form an effective basis for treatment of this condition. In response to injury in the liver, IL-6 mediates the acute-phase response and induces both cytoprotective and mitogenic functions. Hyper-IL-6 is a superagonistic designer cytokine consisting of human IL-6 linked by a flexible peptide chain to the secreted form of the IL-6 receptor. In a mouse model of acute liver failure induced by d-galactosamine administration, a single low dose of a hyper-IL-6-encoding adenoviral vector, in contrast to an adeno-IL-6 vector, maintained liver function, prevented the progression of liver necrosis, and induced liver regeneration, leading to dramatically enhanced survival. Thus, hyper-IL-6 gene therapy may be useful for the treatment of fulminant hepatic failure, which is often fatal even following treatment by transplantation.

Liver regeneration induced by a designer human IL-6/sIL-6R fusion protein reverses severe hepatocellular injury

The cytokine IL-6 plays a significant role in liver regeneration in conjunction with additional growth factors (HGF, TNF-alpha, and TGF-alpha). Many IL-6 effects depend on a naturally occurring soluble IL-6 receptor (sIL-6R). Here, the chimeric protein hyper-IL-6, constructed from the human IL-6 protein fused to a truncated form of its receptor, was found to have superagonistic IL-6 properties, and as such, enhanced liver cell regeneration. Hyper-IL-6 reversed the state of hepatotoxicity and enhanced the survival rates of rats suffering from fulminant hepatic failure after D-galactosamine administration. The hyper-IL-6 protein has a significant potential for use in the treatment of severe human liver diseases.

Effects of ZNC-2381, a new oral compound, on several hepatic injury models and on hepatocellular apoptosis in mice and rats

The hepatoprotective effect of ZNC-2381 (1-(4-aminophenyl) methyl-3-(3-nitrophenyl)-1,3-dihydroimidazo[4,5-b]pyridine-2-one), a novel 2-one dihydroimidazopyridine derivative, has been evaluated in several experimental models of hepatic injury. In mice, oral ZNC-2381, administered at doses of 3, 10 or 30 mgkg(-1), 1 h before induction of hepatic injury with concanavalin A, dose-dependently inhibited increases in serum alanine aminotransferase (ALT) activity. Apoptosis of liver cells, as indicated by DNA fragmentation (nucleosome assay) and DNA-ladder formation (electrophoresis), was also inhibited dose-dependently. ZNC-2381 dose-dependently inhibited concanavalin A-induced increases in serum tumour necrosis factor (TNF)-alpha levels, and TNF-alpha mRNA expression in the liver. Oral ZNC-2381 also dose-dependently inhibited increases in serum ALT activity in mice with hepatic injury induced by Propionibacterium acnes and a bacterial lipopolysaccharide (LPS) or D-galactosamine-LPS, and in rats with D-galactosamine-induced hepatic injury. These results indicate that oral ZNC-2381 inhibits cytokine (TNF-alpha) production and cytokine-related hepatocellular apoptosis, and might thus prevent different types of hepatic injury.