Anti-oxidant ebselen causes the resolution of experimentally induced hepatic fibrosis in rats

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Inverse Association between Serum Selenium Level and Severity of Liver Fibrosis: A Cross-Sectional Study

Selenium has been well recognized for its important role in human health. Prior studies showed that low serum selenium was associated with various diseases, including cardiovascular disease, cancer, infertility, and cognitive decline. Recent studies demonstrated an association between selenium deficiency and liver cirrhosis. In our study, we aimed to explore the association between serum selenium levels and severity of liver fibrosis. In total, 5641 participants at an age of 12 and above, from the 2017–2018 United States National Health and Nutrition Examination Survey, were enrolled. The severity of liver fibrosis was determined by liver ultrasound transient elastography. There was a significant linear decrease in liver stiffness measurement (LSM) values in male groups with increased serum selenium levels. The beta coefficient (β) = −1.045 in male groups. A significantly negative association was also observed in the group of age ≥ 60. In addition, those in the highest quartile of serum selenium had lower LSM values (β = −0.416). This is the first study using LSM to demonstrate the correlation between selenium deficiency and severity of liver cirrhosis. Our findings suggest that a high plasma selenium concentration is negatively correlated with the severity of liver cirrhosis and there are gender and age differences.

Protective effect of ebselen on bleomycin-induced lung fibrosis: analysis of the molecular mechanism of lung fibrosis mediated by oxidized diacylglycerol

The molecular mechanisms underlying the development of pulmonary fibrosis remain unknown, and effective treatments have not yet been developed. It has been shown that oxidative stress is involved in lung fibrosis. Oxidized diacylglycerol (DAG) produced by oxidative stress is thought to play an important role in lung fibrosis. This study assessed the effect of oxidized DAG in an animal model of pulmonary fibrosis induced by aspiration of bleomycin (BLM) into the lungs. The inhibitory effect of ebselen on pulmonary fibrosis was also investigated. In lung fibrotic tissue induced by BLM, an increase in lipid peroxides and collagen accumulation was observed. Moreover, the levels of oxidized DAG, which has strong protein kinase C (PKC) activation activity, were significantly increased over time following the administration of BLM. Western blotting showed that phosphorylation of PKCα and δ isoforms was increased by BLM. Oral administration of ebselen significantly suppressed the increase in oxidized DAG induced by BLM and improved lung fibrosis. PKCα and δ phosphorylation were also significantly inhibited. The mRNA expression of α-smooth muscle actin and collagen I (marker molecules for fibrosis), as well as the production of transforming growth factor-β and tumor necrosis factor-α(a potentially important factor in the fibrotic process), were increased by BLM and significantly decreased by ebselen. The administration of BLM may induce lipid peroxidation in lung tissue, while the oxidized DAG produced by BLM may induce overactivation of PKCα and δ, resulting in the induction of lung fibrosis.

The Role and Mechanisms of Selenium Supplementation on Fatty Liver-Associated Disorder

Non-alcoholic fatty liver disease (NAFLD) is the most frequent chronic liver disease without effective therapy. Selenium, as an essential trace element for humans, is notable for its antioxidant properties. The previous study shows that selenium levels in NAFLD patients are lower than normal ones. Selenium supplementation can effectively alleviate metabolic disorders by relieving anti-oxidative stress and anti-inflammatory regulation. However, the correlation between selenium and NAFLD has not been fully clarified. Herein, we review the current studies on selenium in regulating the different stages of NAFLD and summarize relevant clinical trials to highlight the potential roles of selenium in NAFLD treatment.

Melatonin restores zinc levels, activates the Keap1/Nrf2 pathway, and modulates endoplasmic reticular stress and HSP in rats with chronic hepatotoxicity

BACKGROUND

Melatonin (MLT) is a potent antioxidant molecule that is shown to have a beneficial effect in various pathological situations, due to its action against free radicals.

AIM

To evaluate the effect of MLT on carbon tetrachloride (CCl₄) induced liver injury in rats in terms of oxidative stress, reticular stress, and cell damage.

METHODS

Twenty male Wistar rats (230-250 g) were divided into four groups: Control rats, rats treated with MLT alone, rats treated with CCl₄ alone, and rats treated with CCl₄ plus MLT. CCl₄ was administered as follows: Ten doses every 5 d, ten every 4 d, and seven every 3 d. MLT was administered intraperitoneally at a dose of 20 mg/kg from the 10^th wk to the end of the experiment (16^th wk).

RESULTS

MLT was able to reduce the release of liver enzymes in the bloodstream and to decrease oxidative stress in CCl₄ treated rats by decreasing the level of thiobarbituric acid reactive substances and increasing superoxide dismutase activity, with a lower reduction in serum zinc levels, guaranteeing a reduction in liver damage; additionally, it increased the expression of nuclear factor (erythroid-derived 2)-like 2 and decreased the expression of Kelch-like ECH-associated protein 1. MLT also decreased the expression of the proteins associated with endoplasmic reticulum stress, i.e., glucose-regulated protein 78 and activating transcription factor 6, as well as of heat shock factor 1 and heat shock protein 70.

CONCLUSION

MLT has a hepatoprotective effect in an experimental model of CCl₄-induced liver injury, since it reduces oxidative stress, restores zinc levels, and modulates endoplasmic reticulum stress.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Protective efficacy of thymoquinone or ebselen separately against arsenic-induced hepatotoxicity in rat

Arsenic (As) exposure is associated with adverse health outcomes to the living organisms. In the present study, the hepato-protective ability of thymoquinone (TQ), the active principle of Nigella sativa seed, or ebselen (Eb), an organoselenium compound, against As intoxication in female rats was investigated. For this purpose, animals were allocated randomly into control, As (20 mg/kg), TQ (10 mg/kg), Eb (5 mg/kg), As+TQ, and As+Eb groups that were orally administered for 28 consecutive days. Arsenic exposure resulted in hepatic oxidative damage which was evidenced by marked decreases in antioxidant parameters (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione (GSH)) concomitant with high malondialdehyde (MDA) level. Furthermore, As toxicity induced significant elevations in liver accumulation of As, serum hepatic indices (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin (TB)), and apoptotic marker (B cell lymphoma 2(Bcl2), Bcl-2-associated X protein (Bax), and caspase 3) levels. Additionally, notable increments in hepatic fibrotic markers (epidermal growth factor (EFG) and transforming growth factor beta 1 (TGF-β1)) associated with high nitric oxide, interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-α), and myeloperoxidase (MPO) levels were noticed following As intoxication. Biochemical findings were well-supported by hepatic histopathological screening. The co-treatment of As-exposed rats with TQ or Eb considerably improved liver function and antioxidant status together with lessened hepatic As content, inflammation, apoptosis, and fibrosis. The overall outcomes demonstrated that TQ or Eb ameliorates As-induced liver injury through their favorable antioxidant, anti-inflammatory, anti-apoptotic, and fibrolytic properties.

Selenium and selenoprotein P in nonalcoholic fatty liver disease

Conflicting data link nonalcoholic fatty liver disease (NAFLD), a disease with no currently approved treatment, with selenium (Se) and selenoprotein P (SELENOP), a glycoprotein synthesized and primarily secreted by the hepatocytes, functioning as a Se transporter from the liver to other tissues. This review aims to summarize the evidence between Se, SELENOP, and NAFLD, which may hopefully clarify whether current data on Se and SELENOP in NAFLD warrant further investigation for their diagnostic and therapeutic potential. Most, albeit not all, experimental data show a favorable effect of Se on hepatic steatosis, inflammation, and fibrosis. It seems that Se may exert an antioxidant effect on the liver, at least partly via increasing the activity of glutathione peroxidase, whose depletion contributes to the pathogenesis of hepatic inflammation and fibrosis. Se may also affect metalloproteinases, cytokines, and growth factors participating in the pathogenesis of NAFLD and, most importantly, may induce the apoptosis of hepatic stellate cells, the key players in hepatic fibrosis. However, the association between Se or SELENOP and insulin resistance, which is a principal pathogenetic factor of NAFLD, remains inconclusive. Clinical studies on Se or SELENOP in NAFLD are conflicting, apart from those in advanced liver disease (cirrhosis or hepatocellular carcinoma), in which lower circulating Se and SELENOP are constant findings. Existing data warrant further mechanistic studies in valid animal models of human NAFLD. Prospective cohort studies and possibly randomized controlled trials are also needed to elucidate the diagnostic and therapeutic potential of Se supplementation in selected NAFLD individuals with Se deficiency.

Antifibrogenic effect of melatonin in rats with experimental liver cirrhosis induced by carbon tetrachloride

Background and Aim

Liver diseases are a major public health problem, accounting for a significant number of hospital visits and admissions and an increasing mortality rate. Melatonin (MLT) is a powerful antioxidant molecule that has been shown to be beneficial under various conditions. The objective was to evaluate the effect of MLT on experimental liver cirrhosis induced by carbon tetrachloride (CCl₄) in rats.

Methods

Twenty male Wistar rats (230–250 g) were divided into four groups. I: control group (CO); II: CO + MLT; III: CCl₄; and IV: CCl₄ + MLT. CCl₄ was administered intraperitoneally (i.p.) as follows: 10 doses every 5 days, 10 doses every 4 days, and 7 doses every 3 days. MLT was administered i.p. at a dose of 20 mg/kg from the 10th week to the end of the experiment (16th week).

Results

In the CCl₄ + MLT group, we found that MLT caused a decrease in the level of F2‐isoprostanes and NQO1 expression. We also found that MLT reduced the inflammatory process as shown by decreased expressions of NF‐KB/p65 and inducible nitric oxide synthase (iNOS) and a smaller amount of inflammatory infiltrate. MLT reduced the expression of transforming growth factor beta1 (TGF‐β1), alpha‐smooth muscle actin (α‐SMA), and vascular endothelial growth factor (VEGF). Picrosirius staining showed that MLT decreases fibrosis.

Conclusion

MLT has a potent antifibrogenic effect, modulating the parameters of oxidative stress, angiogenesis, and inflammation.

Synergistic effect of Ebselen and gamma radiation on breast cancer cells

PURPOSE

To explore the synergistic effect of a seleno-organic compound Ebselen (Ebs) and/or γ-radiation to exert antitumor effects on human breast cancer (MCF-7) cell line in vitro.

MATERIALS AND METHODS

Ebs cytotoxicity at various concentrations (10, 25, 50 and 75 μg), cell proliferation and clonogenic assay of Ebs and/or γ-radiation (at 1, 3 and 6 Gy), expression of p-IκBα and NF-κB, inflammatory cytokines levels (TNF-α, IL-2, INF-γ, IL-10 and TGF-β), apoptotic factors (Caspase-3, Granzyme-B and TRAIL) and angiogenic factor (VEGF) were investigated.

RESULTS

The results showed that the effective dosage of this combination was observed at 25 μg/ml of Ebs with γ-radiation at 6 Gy. Data displayed a significant reduction in NF-κB mRNA along with an elevation in granzyme-B mRNA and TRAIL mRNA expression. Furthermore, protein expression of caspase-3 was elevated, whereas p-IκBα and p-NF-κB(p65) protein expression was reduced significantly. Also, a significant decline in TNF-α, IL-2, INF-γ, TGF-β with a significant increase in IL-10 levels were revealed. Meanwhile, a significant decrease in VEGF level and proliferation capacity were observed.

CONCLUSIONS

We conclude that a combination of Ebs with radiotherapy has a major antitumor efficiency in inducing apoptosis and inhibiting cancer cell progression, due to the synergistic effect in regulating gene and protein expression, and in a modulating response of pro-and anti-inflammatory cytokines.

Effects of Copper, Zinc, and Vitamin Complex (Cernevit®) on Hepatic Healing in Rats Experimentally Subjected to Blunt Hepatic Trauma

Solid organ injuries following blunt trauma are frequently encountered. The use of non-operative approach is gradually increasing. Thus, research on the methods that could enhance healing in solid organ injuries is in progress. Agents known to have antioxidant property were used after an experimentally induced blunt hepatic trauma. Thirty-two Wistar albino rats weighing 200 g were dropped from a height of 40 cm on to the right upper abdominal quadrant to produce a grade II-III hepatic injury. Rats were divided into control, Zn-administered, Cu-administered, and vitamin complex-administered groups, with eight rats in each. Aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) levels were measured in the blood samples. The percentage of cells displaying Ki-67 nuclear staining was estimated. The sections were stained with hematoxylin and eosin and the degree of inflammation in the samples was semi-quantitatively assessed. Treatment with zinc, copper, and Cernevit® caused varying levels of decrease in AST, ALT, and LDH levels compared to the control group. Ki-67 positivity was significantly lower in group I compared with groups II and III (p = 0.002). Ki-67 positivity was significantly higher in group II compared to the other groups (p < 0.05). A marked improvement was observed in inflammation in group II. Copper and zinc treatment decreased inflammation as well as blood levels of AST and ALT, and enhanced the healing of traumatized hepatic tissue. However, Cernevit® reduced only the degree of inflammation.

Diethylnitrosamine-induced cirrhosis in Wistar rats: an experimental feasibility study

The experimental models of the development of cirrhosis in rats require a long time. Many studies in animals have demonstrated similarities in histological pattern with human cirrhosis. Just like the relation between cirrhosis and increased lipid peroxidation (LPO), which contributes to the worsening of the disease. However, few studies have focused on the reduction of time to establish cirrhosis and evaluated the expression of heat-shock protein 70 (HSP70) in cirrhotic livers of rodents. The present study proposes the adaptation of an experimental cirrhosis model using diethylnitrosamine (DEN). Twenty-six male Wistar rats, weighing ±270 g, divided into two groups: (i) CO-control and (ii) DEN-diethylnitrosamine. The DEN group received 50 mg/kg of DEN twice a week intraperitoneally for 7 weeks. The model developed cirrhosis in 7 weeks. The liver function tests showed that the animals with DEN-induced cirrhosis had increased levels when compared to control. The histological examination showed changes in the liver architecture, with severe ductal proliferation, signs of chronic damage, cholestasis, lymphocytic infiltrate, steatosis, and extensive parenchymal loss. We also found nodular formations with homogeneous pattern, increased LPO, increased expression of iNOS, TGF beta, α-SMA, and NQO1. However, the HSP70 expression was reduced in cirrhotic animals. This study showed signs of cirrhosis in liver based on biochemical, histological, and molecular analysis. The reduced expression of HSP70 appears to be associated with increased oxidative stress, contributing to the worsening of the disease.

The CYP2E1 inhibitor DDC up-regulates MMP-1 expression in hepatic stellate cells via an ERK1/2- and Akt-dependent mechanism

DDC (diethyldithiocarbamate) could block collagen synthesis in HSC (hepatic stellate cells) through the inhibition of ROS (reactive oxygen species) derived from hepatocyte CYP2E1 (cytochrome P450 2E1). However, the effect of DDC on MMP-1 (matrix metalloproteinase-1), which is the main collagen degrading matrix metalloproteinase, has not been reported. In co-culture experiments, we found that DDC significantly enhanced MMP-1 expression in human HSC (LX-2) that were cultured with hepatocyte C3A cells either expressing or not expressing CYP2E1. The levels of both proenzyme and active MMP-1 enzyme were up-regulated in LX-2 cells, accompanied by elevated enzyme activity of MMP-1 and decreased collagen I, in both LX-2 cells and the culture medium. H2O2 treatment abrogated DDC-induced MMP-1 up-regulation and collagen I decrease, while catalase treatment slightly up-regulated MMP-1 expression. These data suggested that the decrease in ROS by DDC was partially responsible for the MMP-1 up-regulation. ERK1/2 (extracellular signal-regulated kinase 1/2), Akt (protein kinase B) and p38 were significantly activated by DDC. The ERK1/2 inhibitor (U0126) and Akt inhibitor (T3830) abrogated the DDC-induced MMP-1 up-regulation. In addition, a p38 inhibitor (SB203580) improved MMP-1 up-regulation through the stimulation of ERK1/2. Our data indicate that DDC significantly up-regulates the expression of MMP-1 in LX-2 cells which results in greater MMP-1 enzyme activity and decreased collagen I. The enhancement of MMP-1 expression by DDC was associated with H2O2 inhibition and coordinated regulation by the ERK1/2 and Akt pathways. These data provide some new insights into treatment strategies for hepatic fibrosis.

Carbon tetrachloride-induced hepatic injury through formation of oxidized diacylglycerol and activation of the PKC/NF-κB pathway

Protein kinase C (PKC) participates in signal transduction, and its overactivation is involved in various types of cell injury. PKC depends on diacylglycerol (DAG) for its activation in vivo We have previously reported that DAG peroxides (DAG-O(O)H) activate PKC in vitro more strongly than unoxidized DAG, suggesting that DAG-O(O)H, if generated in vivo under oxidative stress, would act as an aberrant signal transducer. The present study examined whether DAG-O(O)H are formed in carbon tetrachloride (CCl(4))-induced acute rat liver injury in association with activation of the PKC/nuclear factor (NF)-κB pathway. A single subcutaneous injection of CCl(4) resulted in a marked increase in hepatic DAG-O(O)H content. At the molecular level, immunohistochemistry and subcellular fractionation combined with immunoblotting localized PKCα, βI, βII and δ isoforms to cell membranes, while immunoblotting showed phosphorylation of the p65 subunit of NF-κB, and immunoprecipitation using isoform-specific anti-PKC antibodies revealed specific association of PKCα and p65. In addition, expression of tumor necrosis factor α (TNFα) and neutrophil invasion increased in the CCl(4)-treated rats. Furthermore, we demonstrated that Vitamin E, one of the most important natural antioxidants that suppresses peroxidation of membrane lipids, significantly inhibited the CCl(4)-induced increase in hepatic DAG-O(O)H content and TNFα expression as well as phosphorylation of PKCα and p65. These data demonstrate for the first time that DAG-O(O)H are generated in the process of CCl(4)-induced liver injury, resulting in activation of the PKC/NF-κB pathway and TNFα-mediated aggravation of liver injury.

Hepatoprotective effects and mechanisms of dehydrocavidine in rats with carbon tetrachloride-induced hepatic fibrosis

AIM OF THE STUDY

The current study was designed to examine the effects and possible mechanisms of dehydrocavidine (DC) on carbon tetrachloride (CCl4)-induced hepatic fibrosis in male Sprague-Dawley (SD) rats.

MATERIALS AND METHODS

Hepatic fibrosis was induced in male rats with CCl4 administration for 12 weeks. Liver histopathological study was performed, and the liver function was examined by determining the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and total bilirubin (TBIL) for evaluating the effect of DC on hepatic fibrosis. The possible mechanisms were investigated by measuring hepatic collagen metabolism and oxidative stress level. Furthermore, oligo microarray analysis of 263 genes was performed, and quantitative real-time RT-PCR was used to verify 4 of the abnormally expressed genes (Bcl2, Cyp3a13, IL18 and Rad50).

RESULTS

DC treatment significantly inhibited the loss of body weight and the increase of liver weight induced by CCl4. DC also improved the liver function of rats as indicated by decreased serum enzymatic activities of ALT, AST, ALP and TBIL. Histopathological results indicated that DC alleviated liver damage and reduced the formation of fibrous septa. Moreover, DC significantly decreased liver hydroxyproline (Hyp) and increased urine Hyp. It also decreased liver malondialdehyde concentration, increased activities of liver superoxide dismutase, catalase and glutathione peroxidase. Microarray analysis revealed that DC altered the expression of genes related to apoptosis, cytokines and other proteins involved in tissue repair.

CONCLUSIONS

Our findings indicate that DC can protect rats from CCl4-induced hepatic fibrosis through reducing oxidative stress, promoting collagenolysis, and regulating fibrosis-related genes.

Hepatoprotective and antioxidant effects of licorice extract against CCl₄-induced oxidative damage in rats

Licorice has been used in Chinese folk medicine for the treatment of various disorders. Licorice has the biological capabilities of detoxication, antioxidation, and antiinfection. In this study, we evaluated the antihepatotoxic effect of licorice aqueous extract (LE) on the carbon tetrachloride (CCl₄)-induced liver injury in a rat model. Hepatic damage, as reveled by histology and the increased activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) activities, and decreased levels of serum total protein (TP), albumin (Alb) and globulin (G) were induced in rats by an administration of CCl₄ at 3 mL/kg b.w. (1:1 in groundnut oil). Licorice extract significantly inhibited the elevated AST, ALP and ALT activities and the decreased TP, Alb and G levels caused by CCl₄ intoxication. It also enhanced liver super oxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), Glutathione S-transferase (GST) activities and glutathione (GSH) level, reduced malondialdehyde (MDA) level. Licorice extract still markedly reverses the increased liver hydroxyproline and serum TNF-α levels induced by CCl₄ intoxication. The data of this study support a chemopreventive potential of licorice extract against liver oxidative injury.

Fibrogenic potential of human multipotent mesenchymal stromal cells in injured liver

Multipotent mesenchymal stromal cells (MSC) are currently investigated clinically as cellular therapy for a variety of diseases. Differentiation of MSC toward endodermal lineages, including hepatocytes and their therapeutic effect on fibrosis has been described but remains controversial. Recent evidence attributed a fibrotic potential to MSC. As differentiation potential might be dependent of donor age, we studied MSC derived from adult and pediatric human bone marrow and their potential to differentiate into hepatocytes or myofibroblasts in vitro and in vivo. Following characterization, expanded adult and pediatric MSC were co-cultured with a human hepatoma cell line, Huh-7, in a hepatogenic differentiation medium containing Hepatocyte growth factor, Fibroblast growth factor 4 and oncostatin M. In vivo, MSC were transplanted into spleen or liver of NOD/SCID mice undergoing partial hepatectomy and retrorsine treatment. Expression of mesenchymal and hepatic markers was analyzed by RT-PCR, Western blot and immunohistochemistry. In vitro, adult and pediatric MSC expressed characteristic surface antigens of MSC. Expansion capacity of pediatric MSC was significantly higher when compared to adult MSC. In co-culture with Huh-7 cells in hepatogenic differentiation medium, albumin expression was more frequently detected in pediatric MSC (5/8 experiments) when compared to adult MSC (2/10 experiments). However, in such condition pediatric MSC expressed alpha smooth muscle more strongly than adult MSC. Stable engraftment in the liver was not achieved after intrasplenic injection of pediatric or adult MSC. After intrahepatic injection, MSC permanently remained in liver tissue, kept a mesenchymal morphology and expressed vimentin and alpha smooth muscle actin, but no hepatic markers. Further, MSC localization merges with collagen deposition in transplanted liver and no difference was observed using adult or pediatric MSC. In conclusion, when transplanted into an injured or regenerating liver, MSC differentiated into myofibroblasts with development of fibrous tissue, regardless of donor age. These results indicate that MSC in certain circumstances might be harmful due to their fibrogenic potential and this should be considered before potential use of MSC for cell therapy.

Catalase and glutathione peroxidase mimics

Overproduction of the reactive oxygen species (ROS) superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)) are increasingly implicated in human disease and aging. ROS are also being explored as important modulating agents in a number of cell signaling pathways. Earlier work has focused on development of small catalytic scavengers of O(2)(-), commonly referred to as superoxide dismutase (SOD) mimetics. Many of these compounds also have substantial abilities to catalytically scavenge H(2)O(2) and peroxynitrite (ONOO(-)). Peroxides have been increasingly shown to disrupt cell signaling cascades associated with excessive inflammation associated with a wide variety of human diseases. Early studies with enzymatic scavengers like SOD frequently reported little or no beneficial effect in biologic models unless SOD was combined with catalase or a peroxidase. Increasing attention has been devoted to developing catalase or peroxidase mimetics as a way to treat overt inflammation associated with the pathophysiology of many human disorders. This review will focus on recent development of catalytic scavengers of peroxides and their potential use as therapeutic agents for pulmonary, cardiovascular, neurodegenerative and inflammatory disorders.

Protective effect of diphenylmethyl selenocyanate against CCl4-induced hepatic injury

Organoselenocyanates represent an important class of chemopreventive agent, which possess antioxidative, antimutagenic as well as cancer chemopreventive properties. The present study is an attempt to evaluate the protective effect of diphenylmethyl selenocyanate -- a synthetic organoselenocyanate against carbon tetrachloride (CCl(4))-induced hepatic damage in Swiss albino mice in vivo. Mice were pretreated with the Se-compound orally in a duration dependent manner (7 and 15 days) to observe its protective action against an acute toxic dose (24 h) of CCl(4) (single injection at a dose of 20 microl and 50 microl kg(-1) b.w.) that induced hepatic necrosis and caused DNA damage (strand breaks) in the hepatocytes. This study revealed that pretreatment with the Se-compound reduced the extent of massive hepatic necrosis in a duration dependent manner, but it had no modulatory effect on hepatocellular apoptosis caused by acute toxic doses of CCl(4). It was also found that the Se-compound could significantly (P < 0.01) prevent the CCl(4)-induced elevation of DNA damage in hepatocytes measured by comet assay in a duration dependent manner. So these findings will further strengthen the view that organoselenocyanate is an effective chemopreventive agent against acute hepatic damage, caused by halogenated alkanes such as CCl(4).

Expression of MMPs and TIMPs in liver fibrosis - a systematic review with special emphasis on anti-fibrotic strategies

In liver tissue matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitors of metalloproteinases, TIMPs) play a pivotal role in both, fibrogenesis and fibrolysis. The current knowledge of the pathophysiology of liver fibrogenesis with special emphasis on MMPs and TIMPs is presented. A systematic literature search was conducted. All experimental models of liver fibrosis that evaluated a defined anti-fibrotic intervention in vivo or in vitro considering MMPs and TIMPs were selected. The methodological quality of all these publications has been critically appraised using an objective scoring system and the content has been summarized in a table.

Melatonin prevents experimental liver cirrhosis induced by thioacetamide in rats

Liver cirrhosis is a critical stage of chronic liver diseases that can produce liver failure, portal hypertension and hepatocarcinoma. Sustained oxidative stress plays a key role in cell damage and fibrosis induced during liver cirrhosis. We evaluated the effect of oxidative stress regulation by melatonin on the development of parenchymal destruction and stellate cell activation in experimental liver cirrhosis. Melatonin was administered to rats with liver cirrhosis induced by thioacetamide (TAA) for 1 or 3 months. Liver injury was assessed by serological analysis, as well as hematoxylin-eosin staining and the in situ apoptosis detection assay in liver sections. Oxidative stress was evaluated by lipoperoxide and reduced glutathione levels, and by the measurement of catalase and superoxide dismutase activities in liver and serum respectively. The activation of stellate cells was evaluated by alpha-smooth muscle actin expression in liver sections. Our results showed that TAA induced oxidative stress with extensive tissue damage and enhanced alpha-smooth muscle actin expression in liver. Melatonin prevented the oxidative stress-related changes associated with TAA toxicity. In conclusion, the study showed that melatonin prevents the tissue damage and fibrosis associated with TAA-induced liver cirrhosis in rats.

Pathological comparison of hepatic-fibrosis models induced by porcine serum and carbon tetrachloride in rats

AIM: To compare liver pathological changes between two different hepatic-fibrosis models induced by porcine serum and carbon tetrachloride in rats.

METHODS: Hepatic fibrosis was induced in rats by biweekly intraperitoneal injection of porcine serum (0.5 mL) or 400 mL/L carbon tetrachloride (2 mL/kg) for 7 weeks. Five rats were randomly selected from the survivals in each group. Liver tissue was removed, fixed, sliced and stained with hematoxylin and esosin for routine light-microscopy, Masson trichrome for collagen, Jame's double ammoniated siver solution for reticulin, and then subjected to semiquantitative evaluation by pathological image analyzer. Another portion of liver tissue was prepared for electron microscopy.

RESULTS: Liver tissue in rats receiving pig serum displayed narrow fibrotic sepatae including obvious collagen deposition and more mesenchymal constituents, and collagen was confined to the septae. Hepatocellular injury is rare. In contrast, in the livers from rats treated with CCl₄, the fibrotic septae were coarse, more cellular and diffuse. The parenchymal damage was more severe and extensive. The fatty metamorphosis of hepatocytes was evident. Semiquantitative analyses suggested that quantity of collagenic fibers and reticular fibers in CCl₄ group were significantly higher than those in porcine serum group.

CONCLUSION: Hepatic fibrosis in rats induced by CCl₄ is more severe than that induced by porcine serum.

The antioxidant and antifibrogenic effects of the glycosaminoglycans hyaluronic acid and chondroitin-4-sulphate in a subchronic rat model of carbon tetrachloride-induced liver fibrogenesis

Hepatic fibrosis involves the interplay of many factors including reactive oxygen species. Recent reports described antioxidant properties of glycosaminoglycans (GAGs). Since several findings have shown that hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S) may act as antioxidant molecules, the aim of this research was to evaluate the antioxidant effects of HYA and C4S treatment in a rat model of liver fibrosis. The effect on tissue inhibitors of metalloproteinases (TIMPs) was also studied. Liver fibrosis was induced in rats by eight intraperitoneal injections of CCl4, twice a week for 6 weeks. HYA or C4S alone (25 mg/kg) or HYA and C4S in combination (12.5 + 12.5 mg/kg) were administered daily by the same route during the 6 weeks. At the end of the 6-week treatment period (24 h after the last dose of GAGs), the following parameters were evaluated: (1) serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, as index of hepatic cell disruption; (2) hepatic conjugated dienes (CD), as index of lipid peroxidation; (3) hepatic TIMPs activity and expression; (4) hepatic superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity, as index of endogenous defences; (5) hepatic hydroxyproline, as index of collagen deposition. CCl4-induced liver fibrosis enhanced lipid peroxidation and TIMPs activation, increased ALT and AST, depleted antioxidants SOD and GPx, and caused collagen deposition in liver tissue. Treatment with GAGs, especially when in combination, successfully reduced ALT and AST rise, lipid peroxidation by evaluating conjugated dienes, TIMPs activation and mRNA expression, partially restored SOD and GPx activities, and limited collagen deposition in the hepatic tissue. The data obtained showed that these molecules were able to limit hepatic injury induced by chronic CCl4 intoxication and especially limited liver fibrosis. They also confirm that HYA and C4S may exert antioxidant mechanism, while reduction of TIMPs expression suggests that GAGs may influence MMPs and TIMPs imbalance in liver fibrosis.