Enhanced hepatic lipid peroxidation in patients with primary biliary cirrhosis

Iron as spirit of life to share under monopoly

Any independent life requires iron to survive. Whereas iron deficiency causes oxygen insufficiency, excess iron is a risk for cancer, generating a double-edged sword. Iron metabolism is strictly regulated via specific systems, including iron-responsive element (IRE)/iron regulatory proteins (IRPs) and the corresponding ubiquitin ligase FBXL5. Here we briefly reflect the history of bioiron research and describe major recent advancements. Ferroptosis, a newly coined Fe(II)-dependent regulated necrosis, is providing huge impact on science. Carcinogenesis is a process to acquire ferroptosis-resistance and ferroptosis is preferred in cancer therapy due to immunogenicity. Poly(rC)-binding proteins 1/2 (PCBP1/2) were identified as major cytosolic Fe(II) chaperone proteins. The mechanism how cells retrieve stored iron in ferritin cores was unraveled as ferritinophagy, a form of autophagy. Of note, ferroptosis may exploit ferritinophagy during the progression. Recently, we discovered that cellular ferritin secretion is through extracellular vesicles (EVs) escorted by CD63 under the regulation of IRE/IRP system. Furthermore, this process was abused in asbestos-induced mesothelial carcinogenesis. In summary, cellular iron metabolism is tightly regulated by multi-system organizations as surplus iron is shared through ferritin in EVs among neighbor and distant cells in need. However, various noxious stimuli dramatically promote cellular iron uptake/storage, which may result in ferroptosis.

Biomarkers of oxidative stress as an assessment of the redox status of the liver in dogs

Background

Oxidative stress is associated with a diverse group of liver disorders across species.

Objectives

Determine whether glutathione (GSH) concentration in plasma and red blood cells correlates with liver GSH concentration in dogs and evaluate whether other markers of systemic oxidative stress, plasma vitamin E and urine 8‐isoprostanes/creatinine (F₂‐IsoPs/Cr) concentrations, correlate with liver GSH.

Animals

Thirty‐four client‐owned dogs undergoing clinically indicated liver biopsy and 15 healthy control dogs.

Methods

Prospective, observational cross‐sectional study. Urine and blood were collected before liver biopsy. Plasma, erythrocyte, and liver GSH were measured using high performance liquid chromatography (HPLC); vitamin E was measured by HPLC, and F₂‐IsoPs/Cr was measured by gas chromatography/mass spectrometry.

Results

All dogs were treated at the discretion of the attending clinician (24/34 received antioxidants; 4/34 fed therapeutic liver diet), which included dogs with primary or secondary liver disease (inflammatory (n = 21), metabolic (n = 9), vascular (n = 2), and neoplastic (n = 2)). Median GSH concentrations in plasma, erythrocyte, and liver were 0.18 mg/dL (range 0.14 to 0.56 mg/dL), 56.7 mg/dL (18.3 to 79.2 mg/dL), and 181 mg/dL (39.9 to 527 mg/dL), respectively. No significant correlations were found between liver GSH and erythrocyte GSH, plasma GSH, vitamin E, or F₂‐IsoPs/Cr. Dogs undergoing clinically indicated liver biopsy had significantly higher urine F₂‐IsoPs/Cr than did healthy controls (5.89 vs 2.98 ng/mg; P < .0001).

Conclusions and Clinical Importance

Erythrocyte and plasma GSH are not indicative of liver GSH concentration in dogs. In addition, dogs undergoing clinically indicated liver biopsy have evidence of increased systemic oxidative stress compared to healthy controls.

Protective Effects of Ginsenosides on 17α-Ethynyelstradiol-Induced Intrahepatic Cholestasis via Anti-Oxidative and Anti-Inflammatory Mechanisms in Rats

The present study was designed to assess the effects and potential mechanisms of ginsenosides on 17[Formula: see text]-ethynyelstradiol (EE)-induced intrahepatic cholestasis (IC). Ginsenoside at doses of 30, 100, 300[Formula: see text]mg/kg body weight was intragastrically (i.g.) given to rats for 5 days to examine the effect on EE-induced IC. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and total bile acid (TBA) were measured. Hepatic malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined. Protein expression of proinflammatory cytokines TNF-[Formula: see text], IL-6 and IL-1[Formula: see text] was analyzed by immunohistochemistry and Western blot. Results indicated that ginsenosides remarkably prevented EE-induced increase in the serum levels of AST, ALT, ALP and TBA. Moreover, the elevation of hepatic MDA content induced by EE was significantly reduced, while hepatic SOD activities were significantly increased when treated with ginsenosides. Histopathology of the liver tissue showed that pathological injuries were relieved after treatment with ginsenosides. In addition, treatment with ginsenosides could significantly downregulate the protein expression of TNF-[Formula: see text], IL-6 and IL-1[Formula: see text] compared with EE group. These findings indicate that ginsenosides exert the hepatoprotective effect on EE-induced intrahepatic cholestasis in rats, and this protection might be attributed to the attenuation of oxidative stress and inflammation.

Dysregulation of antioxidant responses in patients diagnosed with concomitant Primary Sclerosing Cholangitis/Inflammatory Bowel Disease

OBJECTIVE

Primary Sclerosing Cholangitis (PSC) is a chronic cholestatic liver disease that is characterized by severe peri-biliary tract inflammation and fibrosis, elevated oxidative stress and hepatocellular injury. A hallmark of PSC patients is the concurrent diagnosis of Inflammatory Bowel Disease occurring in approximately 70%-80% of PSC patients (PSC/IBD). The objective of this study was to determine the impact of end stage PSC/IBD on cellular antioxidant responses and the formation of protein carbonylation.

METHODS

Using hepatic tissue and whole cell extracts isolated from age-matched healthy humans and patients diagnosed with end stage PSC/IBD, overall inflammation, oxidative stress, and protein carbonylation were assessed by Western blotting, and immunohistochemistry.

RESULTS

Increased immunohistochemical staining for CD3+ (lymphocyte), CD68 (Kupffer cell) and myeloperoxidase (neutrophil) colocalized with the extensive Picrosirius red stained fibrosis confirming the inflammatory aspect of PSC. Importantly, the increased inflammation also colocalized with elevated periportal post-translational modification by the reactive aldehydes 4-HNE, MDA and acrolein. 4-HNE, MDA and acrolein IHC all displayed a significant component in hepatocytes adjacent to fibrotic regions. Furthermore, acrolein was also elevated within the nuclei of periportal inflammatory cells whereas MDA staining was increased in hepatocytes across the lobule. Prussian Blue staining, when compared to the positive controls (ALD, NASH), did not display any evidence of iron accumulation in PSC/IBD livers. Western analysis of PSC/IBD anti-oxidant responses revealed elevated expression of SOD2, GSTπ as well as upregulation of Akt Ser473 phosphorylation. In contrast, expression of GSTμ, GSTA4, catalase, Gpx1 and Hsp70 were suppressed. These data were further supported by a significant decrease in measured GST activity. Dysregulation of anti-oxidant responses in the periportal region of the liver was supported by elevated SOD2 and GSTπ IHC signals in periportal hepatocytes and cholangiocytes. Expression of the Nrf2-regulated proteins HO-1, NAD(P)H quinone reductase (NQO1) and Gpx1 was primarily localized to macrophages. In contrast, catalase staining decreased within periportal hepatocytes and was not evident within cholangiocytes.

CONCLUSIONS

Results herein provide additional evidence that cholestasis induces significant increases in periportal oxidative stress and suggest that there are significant differences in the cellular and subcellular generation of reactive aldehydes formed during cholestatic liver injury. Furthermore, these data suggest that anti-oxidant responses are dysregulated during end-stage PSC/IBD supporting pathological data. This work was funded by NIH5R37AA009300-22 D.R.P.

Role of 4-hydroxynonenal-protein adducts in human diseases

SIGNIFICANCE

Oxidative stress provokes the peroxidation of polyunsaturated fatty acids in cellular membranes, leading to the formation of aldheydes that, due to their high chemical reactivity, are considered to act as second messengers of oxidative stress. Among the aldehydes formed during lipid peroxidation (LPO), 4-hydroxy-2-nonenal (HNE) is produced at a high level and easily reacts with both low-molecular-weight compounds and macromolecules, such as proteins and DNA. In particular, HNE-protein adducts have been extensively investigated in diseases characterized by the pathogenic contribution of oxidative stress, such as cancer, neurodegenerative, chronic inflammatory, and autoimmune diseases.

RECENT ADVANCES

In this review, we describe and discuss recent insights regarding the role played by covalent adducts of HNE with proteins in the development and evolution of those among the earlier mentioned disease conditions in which the functional consequences of their formation have been characterized.

CRITICAL ISSUES

Results obtained in recent years have shown that the generation of HNE-protein adducts can play important pathogenic roles in several diseases. However, in some cases, the generation of HNE-protein adducts can represent a contrast to the progression of disease or can promote adaptive cell responses, demonstrating that HNE is not only a toxic product of LPO but also a regulatory molecule that is involved in several biochemical pathways.

FUTURE DIRECTIONS

In the next few years, the refinement of proteomical techniques, allowing the individuation of novel cellular targets of HNE, will lead to a better understanding the role of HNE in human diseases.

Nitric oxide is a potential mediator of hepatic inflammation and fibrogenesis in autoimmune hepatitis

BACKGROUND

Despite advances in the understanding of the pathophysiological basis of autoimmune hepatitis (AIH), it is still difficult to delineate the mechanisms involved in progression from hepatic inflammation toward fibrosis. Our aim was to study serum concentrations of NO in AIH of different histological severity and possible effects of immunosuppressive therapy on NO production.

MATERIALS AND METHODS

We studied serum NO metabolites (NOx) in 47 consecutive patients with AIH and in 28 age- and sex-matched controls.

RESULTS

Serum NOx concentrations were higher in AIH patients than in controls (10.3 (4.5-27.3 µmol/L) vs. 4.3 (1.6-14.3 µmol/L), p < 0.001). According to liver histology, median NOx concentrations were significantly higher in patients with severe interface hepatitis compared to patients with mild-moderate interface hepatitis (12.3 (4.5-27.3 µmol/L) vs. 9.3 (4.6-20.3 µmol/L), p = 0.029). Similarly, serum NOx concentrations were significantly higher in patients with advanced fibrosis than in those with early fibrosis (12.2 (4.6-27.3 µmol/L) vs. 9.3 (6.6-12.8 µmol/L), p = 0.018). NOx concentrations decreased in 16 AIH patients who were tested also after biochemical remission was achieved (12.6 (4.5-22.8 µmol/L) at baseline and 5.9 (2.8-10.5 µmol/L) after remission, p = 0.001).

CONCLUSION

This study shows that serum NOx levels are associated with the histological severity of AIH. Hepatocyte inflammation and injury may activate hepatic stellate cells and kupffer cells, and the consequences may include release of NO, which ultimately promotes hepatic fibrosis. Immunosuppressive therapy inhibits this process and the production of NO.

Oxidative stress and antioxidant status in patients with autoimmune liver diseases

OBJECTIVE

To estimate oxidative stress and antioxidant components during different stages of autoimmune liver diseases and assess their possible implication on disease progression.

METHODS

We determined several markers of oxidative injury (isoprostane, aldehydes, protein carbonyls, 3-nitrotyrosine, and myeloperoxidase) and antioxidant components (glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase) in whole blood, serum, and urine in 49 patients with autoimmune cholestatic liver diseases (AC) and 36 patients with autoimmune hepatitis (AIH) and healthy subjects matched for sex and age.

RESULTS

Both AC and AIH patients had increased levels of all lipid and protein oxidative injury products and significantly decreased whole blood glutathione levels compared to controls. AIH patients had significantly higher levels of aldehydes and glutathione peroxidase activity and significantly lower protein carbonyl levels compared to AC patients. Protein carbonyl and isoprostane levels increased and glutathione levels decreased gradually with progression from mild fibrosis to severe fibrosis and cirrhosis in both AC and AIH patients. In addition, both cirrhotic AC and AIH patients had significantly higher protein carbonyls compared to non-cirrhotics.

DISCUSSION

We provide novel findings in support of a major contribution of oxidant/antioxidant imbalance in the progression of liver injury in AC and AIH.

The Role of e-NOS in Chronic Cholestasis-Induced Liver and Renal Injury in Rats: The Effect of N-Acetyl Cysteine

Introduction. The role of chronic cholestasis (CC) in liver injury and fibrosis remains unclear. The aims of this study were to define the role of endothelial nitric oxide synthase (e-NOS) in CC and the protective effect of N-acetyl-L-cysteine (NAC) in liver and kidney injury. Materials and Methods. Group A (sham group); Group B (CBDL); and Group C (CBDL + NAC). Group C received daily dosage of NAC (100 mg/kg) intraperitoneally for up to 4 weeks. Results. The rate of bridging fibrosis was higher (100% versus 20%, P = .025), but the intensity of e-NOS in liver was lower in rats that received NAC (1.3 versus 2.7, P = .046). The necrotic area in the kidneys among rats that received NAC was lower at week 4 (48% versus 57%; P < .001). The numbers of e-NOS stained cells in kidney were similar in sham group and the two groups with CBDL. Discussion. NAC reduced the stimulus for liver fibrosis in this rat model of CC and attenuated liver and kidney injury. Our study showed that e-NOS expression increased in liver tissue of rats with CC and that this was reversed by NAC. Treatment with NAC might restore e-NOS protein expression and prevent liver injury in CC.

Hepatic Injury Correlates With Apoptosis, Regeneration, and Nitric Oxide Synthase Expression in Canine Chronic Liver Disease

Assessment of the clinical severity, pathogenesis, and prognosis of canine chronic liver disease poses significant challenges to clinicians and pathologists, relating in part to a lack of standardized terminology and assessment methods and also to a lack of understanding of the pathogenesis of chronic liver disease in the dog. This study graded the severity of necroinflammatory activity in chronic liver disease in dogs using a modification of Ishak’s grading scheme for human chronic liver disease and examined the association of grade score with hepatocellular apoptosis, regeneration, nitric oxide synthase isoform expression, copper and iron accumulation, and indicators of oxidative stress. Formalin-fixed, paraffin-embedded hematoxylin and eosin (HE)–stained liver biopsies from 45 dogs with chronic liver disease and 55 healthy control dogs were graded for various morphologic components of liver injury and response. The cumulative score for grade of necroinflammatory activity was strongly and significantly correlated with immunoreactive labels for hepatocellular proliferation (Ki-67); apoptosis (cleaved caspase-3); inducible nitric oxide synthase (iNOS) in lobular, portal, and septal stromal cells; endothelial nitric oxide synthase (eNOS) in hepatocytes and lobular, portal, and septal stromal cells; and total stainable hepatic iron. A weaker significant correlation was found between grade and accumulation of hepatocellular copper. No significant correlation was found between grade and immunoreactivity for malondialdehyde-protein adducts. These results document a method for grading of the severity of necroinflammatory disease in canine liver biopsies and show an association with increased iNOS and eNOS expression.

Prophylactic effect of resveratrol against ethinylestradiol-induced liver cholestasis

Estrogens, and particularly glucuronides such as ethinylestradiol (EE), have been shown to cause cholestasis in animal studies, by reducing bile acid uptake by hepatocytes. The aim of the present article was to investigate anticholestatic activity of resveratrol (RES) against liver cholestasis induced by EE in adult female rats. The daily oral administration of the RES at a concentration of 25 mg/kg body weight for 15 days to rats treated with EE (100 μg/kg body weight for 5 days) resulted in a significant protection against EE-induced decrease in both serum cholesterol and bile acid levels as well as against an increase of serum bilirubin concentration. The treatment also resulted in a significant increase in hepatic superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase activities as well as hepatic protein-bound and nonprotein sulfhydryl groups. RES inhibited serum alkaline phosphatase, alanine aminotransferase, pi-glutathione-S-transferase, gamma-glutamyl transpeptidase, and alpha-glutathione-S-transferase activities, as well as reduced serum tumor necrosis factor-alpha, nitric oxide, and hepatic malondialdehyde as compared to EE-treated rats. The results clearly suggest that RES has a powerful prophylactic action in cholestasis induced by EE. Taken together, RES has potential as a preventive and therapeutic agent for cholestasis and deserves clinical trial in the near future as an adjuvant therapy in women treated with estrogen.

Beneficial effect of docosahexaenoic acid on cholestatic liver injury in rats

Bile duct obstruction and subsequent cholestasis are associated with hepatocellular injury, cholangiocyte proliferation, stellate cell activation, Kupffer cell activation, oxidative stress, inflammation and fibrosis. Docosahexaenoic acid (DHA) is an essential polyunsaturated fatty acid that has been shown to possess health beneficial effects, including hepatoprotection. However, the molecular mechanism of DHA-mediated hepatoprotection is not fully understood. In the present study, we report the protective effect of DHA on cholestatic liver injury. Cholestasis was produced by bile duct ligation (BDL) in male Sprague-Dawley rats for 3 weeks. Daily administration of DHA was started 2 weeks before injury and lasted for 5 weeks. In comparison with the control group, the BDL group showed hepatic damage as evidenced by histological changes and elevation in serum biochemicals, ductular reaction, fibrosis, inflammation and oxidative stress. These pathophysiological changes were attenuated by chronic DHA supplementation. DHA alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), intereukin-1beta, connective tissue growth factor and collagen expression. The anti-fibrotic effect of DHA was accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad 2/3 activity critical to the fibrogenic potential of TGF-β1. DHA also attenuated BDL-induced leukocyte accumulation and nuclear factor-κB (NF-κB) activation. Further studies demonstrated an inhibitory effect of DHA on redox-sensitive intracellular signaling molecule extracellular signal-regulated kinase (ERK). Taken together, the hepatoprotective, anti-inflammatory and anti-fibrotic effects of DHA seem to be multifactorial. The beneficial effects of chronic DHA supplementation are associated with anti-oxidative and anti-inflammatory potential as well as down-regulation of NF-κB and transforming growth factor beta/Smad signaling probably via interference with ERK activation.

Advances in methods for the determination of biologically relevant lipid peroxidation products

Lipid peroxidation is recognized to be an important contributor to many chronic diseases, especially those of an inflammatory pathology. In addition to their value as markers of oxidative damage, lipid peroxidation products have also been shown to have a wide variety of biological and cell signalling effects. In view of this, accurate and sensitive methods for the measurement of lipid peroxidation products are essential. Although some assays have been described for many years, improvements in protocols are continually being reported and, with recent advances in instrumentation and technology, highly specialized and informative techniques are increasingly used. This article gives an overview of the most currently used methods and then addresses the recent advances in some specific approaches. The focus is on analysis of oxysterols, F(2)-isoprostanes and oxidized phospholipids by gas chromatography or liquid chromatography mass spectrometry techniques and immunoassays for the detection of 4-hydroxynonenal.

Primary biliary cirrhosis is associated with oxidative stress and endothelial dysfunction but not increased cardiovascular risk

AIM

  Primary biliary cirrhosis (PBC) is a chronic cholestatic disease which is associated with hypercholesterolaemia. Further, cholestatic diseases are associated with deficiencies of anti-oxidant vitamins. Despite these associations PBC is not associated with an increase in cardiovascular mortality. The aim of this study is to assess if primary biliary cirrhosis is associated with oxidative stress, endothelial dysfunction and alteration of vascular compliance which is a surrogate marker for cardiovascular risk.

METHODS

  Fifty-one PBC patients and 34 control subjects were studied. Lipid soluble vitamins A, and E in addition to ascorbate and carotenoids were measured to assess anti-oxidant status. C-reactive protein, hydroperoxides and adhesion molecules sICAM-l/sVCAM-l were assessed as serological measures of endothelial function. Finally, measures of vascular compliance were assessed by applanation tonometer.

RESULTS

  CRP, sICAM and sVCAM were all significantly higher in PBC patients (469.14 vs 207.13, P < 0.001; 768.12 vs 308.03,P < 0.001; 708.40 vs 461.31, P < 0.001) whilst anti-oxidant vitamin levels were lower in PBC patients, with ascorbate, vitamin E and vitamin A all significantly lower in PBC patients (39.91 vs 72.68, P < 0.001; 2.63 vs 3.14, P = 0.02; 1.08 vs 1.81, P < 0.001). Despite these findings PBC patients have a lower pulse wave velocity than control subjects (8.22 m/s vs 8.78 m/s, P = 0.022).

CONCLUSION

  PBC patients appear to have reduced vascular risk as assessed by pulse wave velocity but concurrently have evidence of endothelial dysfunction, inflammation and anti-oxidant deficiency.

Enhanced hepatic Nrf2 activation after ursodeoxycholic acid treatment in patients with primary biliary cirrhosis

The cytoprotective mechanisms of ursodeoxycholic acid (UDCA) in primary biliary cirrhosis (PBC) have not been fully clarified. UDCA has some antioxidant properties. Nuclear factor-E2-related factor-2 (Nrf2) plays a critical role in protecting a variety of tissues against oxidative stress. Therefore, to investigate the potential antioxidant effects of UDCA in PBC, we determined the intracellular status of both oxidant stress and antioxidant defenses in paired pre- and posttreatment liver biopsies from 13 PBC patients by immunodetection of 8-hydroxydeoxyguanosine (8-OHdG), Nrf2-, and Nrf2-mediated antioxidant proteins. After UDCA treatment, the number of 8-OHdG-positive hepatocytes or bile duct cells decreased with improvement of hepatic injury. The hepatic levels of both total and phosphorylated Nrf2 protein were increased, along with upregulation of nuclear phosphorylated Nrf2 expression in bile duct cells. In addition, the levels of both thioredoxin (TRX) and thioredoxin reductase 1 (TrxR1) protein were increased in the liver after UDCA. The upregulation of hepatic TRX or TrxR1 protein expression positively correlated with that of total Nrf2 protein expression. In conclusion, UDCA treatment can enhance hepatic Nrf2 activation and upregulate hepatic TRX and TrxR1 protein expression. Hepatic Nrf2 activation may play a role in the therapeutic response to UDCA in PBC.

Liver fibrosis in biliary atresia

Biliary atresia (BA) is the most common cholestatic liver disorder requiring liver transplantation in children. Hepatic fibrosis is not only a universal and prominent feature of BA, it is also the most important predictor of outcome following portoenterostomy (PE). Without PE, the progression of hepatic fibrosis is quite dramatic, such that liver cirrhosis is established within a few weeks after birth. Etiologies and molecular networks underpinning such an expeditious fibrogenic process have not been well established. However, immune and nonimmune factors implicated in the pathogenesis of BA, and the resultant cholestasis and oxidative stress, appear to be the main triggers of hepatic fibrosis in BA. Owing to a lack of validated noninvasive tools to monitor liver fibrosis, current prognostic models of BA entail clinical and biochemical variables reflecting liver dysfunction rather than hepatic fibrogenesis. Further work is necessary to validate the results of preliminary studies indicating a good relationship between liver fibrosis determined by transient elastography and other clinical and routinely performed biochemical parameters in pediatric patients. Although a prime candidate for a number of antifibrotic therapies on the horizon, owing to poor understanding of molecular mechanisms, a clear framework of antifibrotic targets has not been outlined in BA. Similarly, specific antifibrotic therapies have not yet been incorporated in clinical practice, limiting these measures to prompt diagnosis and PE operation, prevention and treatment of cholangitis and optimal nutritional support including the administration of fat-soluble vitamins.

Chronic administration of ursodeoxycholic acid decreases portal pressure in rats with biliary cirrhosis

Liver cirrhosis is characterized by increased IHR (intrahepatic resistance) and lipid peroxidation, and decreased antioxidative defence. The present study investigates the effects of administration for 1 month of the antioxidant UDCA (ursodeoxycholic acid) in BDL (bile-duct-ligated) cirrhotic rats. Splanchnic haemodynamics, IHR, hepatic levels of TBARS (thiobarbituric acid-reacting substances), GSH (glutathione), SOD (superoxide dismutase) activity, nitrite, PIIINP (N-terminal propeptide of type III procollagen) and collagen deposition, histological examination of liver, mRNA expression of PIIIP-alpha1 (type III procollagen) and TGF-beta1 (transforming growth factor-beta1), protein expression of TXS (thromboxane synthase) and iNOS (inducible NO synthase), and TXA2 (thromboxane A2) production in liver perfusates were measured. The results showed that portal pressure and IHR, hepatic levels of PIIINP, hepatic collagen deposition, mRNA expression of PIIIP-alpha1 and TGF-beta1, protein expression of iNOS and TXS, and production of TXA2 in liver perfusates were significantly decreased in UDCA-treated BDL rats. The increased levels of hepatic GSH and SOD activity and decreased levels of TBARS and nitrite were also observed in UDCA-treated BDL rats. In UDCA-treated BDL rats, the reduction in portal pressure resulted from a decrease in IHR, which mostly acted through the suppression of hepatic TXA2 production and lipid peroxidation, and an increase in antioxidative defence, leading to the prevention of hepatic fibrosis.

Oxidized low-density-lipoprotein accumulation is associated with liver fibrosis in experimental cholestasis

OBJECTIVE

The aim of the present study was to examine the probable relationship between the accumulation of oxLDL and hepatic fibrogenesis in cholestatic rats.

INTRODUCTION

There is growing evidence to support the current theories on how oxidative stress that results in lipid peroxidation is involved in the pathogenesis of cholestatic liver injury and fibrogenesis. One of the major and early lipid peroxidation products, OxLDL, is thought to play complex roles in various immuno-inflammatory mechanisms.

METHODS

A prolonged (21-day) experimental bile duct ligation was performed on Wistar-albino rats. Biochemical analysis of blood, histopathologic evaluation of liver, measurement of the concentration of malondialdehyde (MDA) and superoxide-dismutase (SOD) in liver tissue homogenates, and immunofluorescent staining for oxLDL in liver tissue was conducted in bile-duct ligated (n=8) and sham-operated rats (n=8).

RESULTS

Significantly higher levels of MDA and lower concentrations of SOD were detected in jaundiced rats than in the sham-operated rats. Positive oxLDL staining was also observed in liver tissue sections of jaundiced rats. Histopathological examination demonstrated that neither fibrosis nor other indications of hepatocellular injury were found in the sham-operated group, while features of severe hepatocellular injury, particularly fibrosis, were found in jaundiced rats.

CONCLUSION

Our results support the finding that either oxLDLs are produced as an intermediate agent during exacerbated oxidative stress or they otherwise contribute to the various pathomechanisms underlying the process of liver fibrosis. Whatever the mechanism, it is clear that an association exists between elevated oxLDL levels and hepatocellular injury, particularly with fibrosis. Further studies are needed to evaluate the potential effects of oxLDLs on the progression of secondary biliary cirrhosis.

Tetrathiomolybdate protects against bile duct ligation-induced cholestatic liver injury and fibrosis

Tetrathiomolybdate (TM), a potent copper-chelating drug, was initially developed for the treatment of Wilson's disease. Our working hypothesis is that the fibrotic pathway is copper-dependent. Because biliary excretion is the major pathway for copper elimination, a bile duct ligation (BDL) mouse model was used to test the potential protective effects of TM. TM was given in a daily dose of 0.9 mg/mouse by means of intragastric gavage 5 days before BDL. All the animals were killed 5 days after surgery. Plasma liver enzymes and total bilirubin were markedly decreased in TM-treated BDL mice. TM also inhibited the increase in plasma levels of tumor necrosis factor (TNF)-alpha and transforming growth factor (TGF)-beta1 seen in BDL mice. Cholestatic liver injury was markedly attenuated by TM treatment as shown by histology. Hepatic collagen deposition was significantly decreased, and it was paralleled by a significant suppression of hepatic smooth muscle alpha-actin and fibrogenic gene expression in TM-treated BDL mice. Although the endogenous antioxidant ability was enhanced, oxidative stress as shown by malondialdehyde and 4-hydroxyalkenals, hepatic glutathione/oxidized glutathione ratio, was not attenuated by TM treatment, suggesting the protective mechanism of TM may be independent of oxidative stress. In summary, TM attenuated BDL-induced cholestatic liver injury and fibrosis in mice, in part by inhibiting TNF-alpha and TGF-beta1 secretion. The protective mechanism seems to be independent of oxidative stress. Our data provide further evidence that TM might be a potential therapy for hepatic fibrosis.

Does Pharmaconutrition with L-Arginine and/or α-Tocopherol Improve the Gut Barrier in Bile Duct Ligated Rats?

BACKGROUND/AIM

Nitric oxide supplementation and antioxidant therapy modulate gut barrier function, but the relationships between enhanced nitric oxide production, antioxidant administration, and biliary obstruction remain unclear. We evaluated the role of nitric oxide and alpha-tocopherol supplementation in bile duct ligated rats.

METHODS

Fifty male Wistar albino rats underwent sham operation (group I; control animals) or bile duct ligation (groups II, III, IV, and V). The ligation groups received the following regimens: standard pellet diet (group II), pellet diet plus intramuscularly administered alpha-tocopherol (group III), and L-arginine-enriched pellet diet without (group IV) or with (group V) alpha-tocopherol. Nitric oxide, malondialdehyde, and alpha-tocopherol concentrations were assessed at the end of 3 weeks. Liver and intestinal samples were scored histologically. Mesenteric lymph node and liver cultures were assessed for bacterial translocation.

RESULTS

The liver malondialdehyde concentration was highest in group III. The nitric oxide content in the liver was higher in groups III and V, as were the blood alpha-tocopherol levels. Bacterial translocation was evident following bile duct ligation, but did not differ among the treatment groups. Intestinal histology revealed that group III had the lowest villus height, that group V had the least villus count, and that group II had the highest mucous cell count. The fibrosis scores were higher in groups IV and V.

CONCLUSIONS

An obvious effect of alpha-tocopherol (with or without L-arginine) on the gut barrier could not be demonstrated. Moreover, the L-arginine-enriched diet promoted fibrosis in the liver. Thus, while biliary duct obstruction triggers bacterial translocation, nitric oxide and/or alpha-tocopherol supplementation did not seem to improve the gut barrier in our model.

Implications of oxidative stress and hepatic cytokine (TNF-alpha and IL-6) response in the pathogenesis of hepatic collagenesis in chronic arsenic toxicity

INTRODUCTION

Noncirrhotic portal fibrosis has been reported to occur in humans due to prolonged intake of arsenic contaminated water. Further, oxystress and hepatic fibrosis have been demonstrated by us in chronic arsenic induced hepatic damage in murine model. Cytokines like tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) are suspected to play a role in hepatic collagenesis. The present study has been carried out to find out whether increased oxystress and cytokine response are associated with increased accumulation of collagen in the liver due to prolonged arsenic exposure and these follow a dose-response relationship.

METHODS

Male BALB/c mice were given orally 200 microl of water containing arsenic in a dose of 50, 100, and 150 mug/mouse/day for 6 days a week (experimental group) or arsenic-free water (<0.01 microg/l, control group) for 3, 6, 9 and 12 months. Hepatic glutathione (GSH), protein sulfhydryl (PSH), glutathione peroxidase (GPx), Catalase, lipid peroxidation (LPx), protein carbonyl (PC), interleukin (IL-6), tumor necrosis factor (TNF-alpha), arsenic and collagen content in the liver were estimated from sacrificed animals.

RESULTS

Significant increase of lipid peroxidation and protein oxidation in the liver associated with depletion of hepatic thiols (GSH, PSH), and antioxidant enzymes (GPx, Catalase) occurred in mice due to prolonged arsenic exposure in a dose-dependent manner. Significant elevation of hepatic collagen occurred at 9 and 12 months in all the groups associated with significant elevation of TNF-alpha and IL-6. However, arsenic level in the liver increased progressively from 3 months onwards. There was a positive correlation between the hepatic arsenic level and collagen content (r = 0.8007), LPx (r = 0.779) and IL-6 (r = 0.7801). Further, there was a significant negative correlation between GSH and TNF-alpha (r = -0.5336)) and LPx (r = -0.644).

CONCLUSION

Increasing dose and duration of arsenic exposure in mice cause progressive increase of oxystress and elevation of cytokines associated with increasing level of collagen in the liver.

[Significance of serum oxidative stress related markers and genotype of GST gene in the pathogeneses of primary biliary cirrhosis]

The studies using an immunohistological technique revealed that overexpression of oxidative stress-related substance such as HNE was observed in the liver of primary biliary cirrhosis patients. These data suggested that oxidative stress participated in the pathogenesis of primary biliary cirrhosis. Therefore we analyzed serum oxdative stress marker (8-OHdG) and anti oxidative substances (Mn-SOD and TRX) to evaluate their clinical significance. In addition we analyzed the genotype of anti oxidative substance GST that has been reported to relate susceptibility of autoimmune disease. Serum levels of 8-OHdG, Mn-SOD and TRX in PBC patients were significantly higher than those of healthy subjects (P<0.001). Though there was no relation between serum level of 8-OHdG and clinical data, positive correlation between serum level of Mn-SOD, TRX and serum level of ALP, IgM was observed. Positive correlation was also observed between serum level of Mn-SOD and TRX. Serum levels of Mn-SOD of patients who responded to UDCA therapy were significantly higher than those of patients who did not response to therapy (P<0.01). Although genotypic difference of GSTM1 and GSTT1 by peripheral blood mononuclear cells did not relate to susceptibility of PBC, serum titer of AMA of GSTM1 null and GSTT1 null patients were significantly higher than those of GSTM1 positive and/or GSTT1 positive patients (P< 0.05). These findings suggest that serum oxidative stress-related markers may reflect the extent of liver damage of PBC, and may relate to the efficacy of UDCA therapy on PBC. It also made clear that genotype of GST related to the titer of AMA.

The effect of N-acetylcysteine (NAC) on liver and renal tissue inducible nitric oxide synthase (iNOS) and tissue lipid peroxidation in obstructive jaundice stimulated by lipopolysaccharide (LPS)

Morbidity and mortality rates are very high in obstructive jaundice when it is associated with sepsis and multiple organ failure. Nitric oxide (NO) formation and increased expression of inducible nitric oxide synthase (iNOS) also take place in obstructive jaundice (OJ). N-Acetylcysteine (NAC) has a beneficial effect by demonstrating anti-inflammatory activity such as inhibits cytokine expression/release, inhibiting the adhesion molecule expression and inhibiting nuclear factor kappa B (NFkappaB). The aim of this study was to investigate the effects of NAC on liver and renal tissue iNOS, and liver tissue lipid peroxidation in lipopolysaccharide (LPS) induced obstructive jaundice. We randomized 48 rats into six groups. Group A: Sham group; group B: OJ group; group C: OJ+NAC; group D: OJ+LPS (Escherichia coli LPS serotype L-2630, 100mg, Sigma) group E: OJ+NAC+LPS; group F: OJ+LPS+NAC. NAC was started subcutaneously 100mg/kg. LPS was injected intraperitoneally and then at the tenth day we sacrificed the rats. Liver malondialdehyde (MDA) increased and liver ATPase decreased in groups B-D when compared to group A. After the administration of NAC (groups C-E), liver MDA levels decreased, tissue ATPase levels increased as compared to other groups. The liver and renal tissue iNOS expression was increased in groups B, D, and F. After the administration of NAC (groups C-E) the liver and renal tissue iNOS expression were decreased. Our results indicated that NAC prevented the deleterious effects of LPS in OJ by reducing iNOS expression via lipid peroxidation in liver and renal tissue; if it was administrated before LPS. But NAC failed to prevent the iNOS expression and lipid peroxidation if there was established endotoxemia in OJ.

Oxidant stress in type I autoimmune hepatitis: the link between necroinflammation and fibrogenesis?

Autoimmune hepatitis (AIH) is a chronic liver disease of unknown aetiology characterized by circulating autoantibodies, hyperglobulinaemia and interface hepatitis. The mechanisms of progression from initial autoimmune attack to fibrosis and cirrhosis are unclear but oxidant stress may be involved. Markers of lipid peroxidation, antioxidant status, hepatic fibrogenesis and liver function were measured in blood and urine in 35 controls and in 33 patients with type-1 AIH; histology was assessed in 18 patients. In AIH, markers of lipid peroxidation were significantly elevated (8-isoprostane in both plasma and urine P < 0.001; plasma malondialdehyde P = 0.017). Total antioxidant capacity in protein-free serum and total glutathione in both whole blood and plasma were significantly reduced (P = 0.007, P = 0.037, P < 0.001, respectively). The antioxidants selenium, vitamin A and vitamin E were significantly decreased (P = 0.007, P < 0.001, P = 0.025, respectively); vitamin C was unchanged. Urinary 8-isoprostane correlated positively with interface hepatitis and necroinflammatory score and with hepatic fibrogenesis (type III procollagen peptide). Interface hepatitis correlated negatively with vitamin A and whole blood total glutathione. Oxidant stress, as reflected in blood and urine by a wide range of pro- and antioxidant markers, is a significant feature of AIH and provides a probable mechanism linking hepatic necroinflammation to fibrogenesis and disease progression.

A case of advanced primary biliary cirrhosis treated with granulocyte and monocyte apheresis

Generally, the most effective treatment for advanced primary biliary cirrhosis (PBC) is liver transplantation, but adjunct therapies are needed. We report here a first case of advanced PBC treated with a new immunotherapy, granulocyte and monocyte apheresis (GCAP). A column (Adacolumn, Japan Immunoresearch Laboratory Takasaki, Japan) was filled with cellulose acetate beads to selectively adsorb granulocytes and monocytes/macrophages. A 49-year-old woman was diagnosed with PBC in 1987. In June 2001, steroid pulse therapy and adjuvant fresh frozen plasma was given for moderate jaundice but without success. In July, as total bilirubin rapidly increased, treatment with GCAP was started and succeeded in suppressing the rapid deterioration of total bilirubin (value changes after each of four applications: 15.4-->14.0, 27.2-->25.1, 25.8-->24.0, 25.7-->23.7 mg/dL) and improving prothrombin time (16.4-->14.5 s). Although GCAP therapy did not prevent a fatal outcome, it suppressed rapid deterioration of jaundice and increased quality of life for a month.

4-Hydroxy-2-nonenal: a product and mediator of oxidative stress

The onset of lipid peroxidation within cellular membranes is associated with changes in their physiochemical properties and with the impairment of enzymatic functions located in the membrane environment. There is increasing evidence that aldehydic molecules generated endogenously during the process of lipid peroidation are causally involved in most of the pathophysiological effects associated with oxidative stress in cells and tissues. 4-Hydroxy-2-nonenal (HNE), among them, is believed to be largely responsible for cytopathological effects observed during oxidative stree in vivo and has achieved the status of one of the best recognized and most studied of the cytotoxic products of lipid peroxidation. In the present review, I provide a comprehensive summary of HNE, as the product and mediator or oxidative stress.

High-molecular-mass isoform of aminopeptidase N/CD13 in serum from cholestatic patients

BACKGROUND

Because non-denaturing electrophoresis and aminopeptidase activity staining often detect noncovalent multi-enzyme complexes, we adopted procedures to specifically detect the aminopeptidase N (APN) molecule itself in liver disease serum.

METHODS

Sera or their immunoprecipitate with anti-APN monoclonal antibody were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) or two-dimensional electrophoresis and subsequent Western blotting with rabbit anti-APN serum.

RESULTS

In all the patient sera examined, the 140-kDa APN isoform was predominant. In all the sera from 10 patients with cholestatic diseases (8 with extra-hepatic cholestasis and 2 with primary biliary cirrhosis), we observed the 260-kDa isoform that was immunoprecipitated with monoclonal APN antibodies and had a similar isoelectric point to the 140-kDa isoform. However, the 260-kDa isoform was observed faintly in 2 out of 12 patients with other liver diseases, including chronic hepatitis and cirrhosis.

CONCLUSIONS

We found a novel high-molecular-mass APN isoform (260-kDa) in serum, which is highly likely to be a homodimer of APNs bound covalently and a promising marker of cholestasis. This suggests increased cross-linking reaction between two APN molecules in cholestatic patients.

Oxidant stress is a significant feature of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic cholestatic disorder characterised by an immunological, and often granulomatous, attack on bile ducts leading to fibrosis, cirrhosis, liver failure and death. Animal and human studies suggest that oxidant stress plays a key role in progression of other liver diseases, but no comprehensive investigation has been performed previously in PBC. A wide range of lipid peroxidation and antioxidant markers were measured in the blood and urine of 41 patients with histologically confirmed PBC. Lipid peroxidation markers were significantly elevated [plasma and urinary 8-isoprostane, P<0.001; plasma malondialdehyde (MDA), P=0.007] compared to age- and sex-matched controls. The most striking antioxidant depletion occurred with plasma total glutathione where levels were significantly reduced (30% of controls). Total serum antioxidant levels were decreased (P=0.013) and serum selenium and vitamin A were also lower (both P<0.001); vitamins C and E were normal. Most patients had early disease biochemically and were Child-Pugh grade A. Urinary 8-isoprostane correlated positively with Ludwig stage and markers of hepatic injury and cholestasis. This study clearly demonstrates that oxidant stress, as reflected in a comprehensive spectrum of lipid peroxidation and antioxidant markers, is a significant feature of early-stage PBC.

Expression of uncoupling protein-2 in biliary epithelial cells in primary biliary cirrhosis

BACKGROUND/AIMS

Uncoupling proteins are thought to protect cells from oxidative stresses. Because uncoupling protein-2 is expressed in liver and reactive oxygen species are involved in pathogenesis of various liver diseases, this protein may protect liver cells from disease-associated oxidative stress. However, uncoupling protein-2 expression in human liver has not been examined.

METHODS

We investigated hepatic uncoupling protein-2 distribution in various liver diseases including primary biliary cirrhosis, autoimmune hepatitis, chronic viral hepatitis, and histologically normal liver by immunohistochemistry.

RESULTS

Uncoupling protein-2 was expressed in some hepatocytes, however, the degree of hepatocytic uncoupling protein-2 expression did not differ significantly among liver diseases and normal liver. Uncoupling protein-2 was abundant in biliary epithelial cells in primary biliary cirrhosis but not in other liver specimens. Enhanced uncoupling protein-2 expression in biliary epithelial cells was specific for primary biliary cirrhosis and did not result simply from cholestasis. The percentage of uncoupling protein-2 positive bile ducts in primary biliary cirrhosis patients treated with ursodeoxycholic acid was significantly lower than in untreated patients.

CONCLUSIONS

These results suggest that uncoupling protein-2 is involved in the pathogenesis of primary biliary cirrhosis.

The effects of antithrombin-III on inducible nitric oxide synthesis in experimental obstructive jaundice. An immunohistochemical study

The absence of bile in the gastrointestinal tract stimulates bacterial overgrowth and bacterial translocation. In the response to endotoxin and LPS-induced endotoxemia which may be prevented by antithrombin-III (AT-III); endothelial cells; and various cells release cytokines, nitric oxide (NO) and other mediators. The purpose of this study was to examine blood NO levels and renal inducible NO synthase (iNOS) expression and determine whether AT-III has an inhibiting effect on renal injury and iNOS expression in obstructive jaundice (OJ). Forty rats were randomized into four groups: group A (Sham), group B (Sham+AT-III, 250 IU kg(-1)), group C (OJ), group D (OJ+AT-III, 250 IU kg(-1)). All animals were sacrificed on the 10th day and blood samples were taken for bilirubin and NO level determination. In addition, iNOS expression of the renal tissues was evaluated immunohistochemically. Blood NO levels were found to be 32.99 micromol l(-1) in group A, 32.26 micromol l(-1) in group B, 46.33 micromol l(-1) in group C, and 34.71 micromol l(-1) in group D. The intensity of iNOS staining in the OJ+AT-III group was less than the intensity of iNOS staining in the OJ group in the renal tissue. This study shows that OJ causes increased production of NO in blood and increased iNOS expression in the kidney. AT-III inhibits iNOS expression and reduces the level of blood NO. Thus, our findings indicate that under conditions of OJ, AT-III limits renal cellular injury by inhibiting LPS-induced iNOS expression.

Damaged interlobular bile ducts in primary biliary cirrhosis show reduced expression of glutathione-S-transferase-pi and aberrant expression of 4-hydroxynonenal

BACKGROUND/AIMS

Chronic inflammation induces oxidative stress by producing reactive oxygen species. We investigated how the oxidative stress associated with chronic cholangitis induce bile duct damages in primary biliary cirrhosis.

METHODS

The intracellular status of lipid peroxidation due to oxidative stress and that of glutathione, an endogenous cytoprotective molecule, were examined in primary biliary cirrhosis and controls by immunostaining of 4-hydroxynonenal and glutathione-S-transferase-pi. The former is a by-product of lipid peroxidation, and the latter is involved in the formation of intracellular glutathione.

RESULTS

In the damaged bile ducts of primary biliary cirrhosis, glutathione-S-transferase-pi expression was markedly reduced, reflecting reduction of intracellular glutathione, and perinuclear expression of 4-hydroxynonenal was frequent, reflecting active lipid peroxidation associated with biliary epithelial damages. There was diffuse/luminal expression of 4-hydroxynonenal in the bile ducts frequent in primary biliary cirrhosis and controls, likely reflecting absorption of 4-hydroxynonenal, also a component of oxidized low-density lipoprotein, from bile via scavenger receptor class B type 1 on biliary epithelium.

CONCLUSIONS

The data suggest that lipid peroxidation in the bile ducts with reduced expression of glutathione-S-transferase-pi, may be an important pathologic process leading to the bile duct damage of primary biliary cirrhosis.

Biochemical and morphological changes in herniated human intervertebral disc

The molecular and morphologic features of herniated human intervertebral disc tissues are of particular importance to clarify the pathogenesis. The present study analyzed the biochemical and morphological features of herniated intervertebral disc tissues to determine the constituent factors responsible for intervertebral disc herniation. A total of 32 herniated disc specimens and 4 control disc samples were analyzed. Collagen subunit composition, collagenase activity, lipid peroxidation level, caspase-3 activity, metal levels, morphologic studies, and genetic analysis were performed on herniated disc tissues of chronic (group A) and acute (group B) group and compared with findings of control group. Nick translation analysis in situ revealed apoptotic-positive stained DNA fragments as black-brown spots in herniated disc tissues. The presence of type II collagen in control disc samples and its absence in herniated samples were confirmed immunohistochemically. The increased caspase-3 activity, the apoptotic-positive stained DNA fragments, and the electron microscopic findings suggest enhanced programmed cell death in herniated discs. The significant increase in lipid peroxidation levels and collagenase activity, and the low metal levels suggest the enhancement of cell death signals in herniated discs, caused by oxygen stress. Linkage analysis of herniated disc tissues in Japanese individuals may suggest ethnic variation. These findings may be helpful in understanding the pathogenesis of herniated disc disease.