Changes in Liver Ganglioside Metabolism in Obstructive Cholestasis - the Role of Oxidative Stress.

Bile acids have been implicated in cholestatic liver damage, primarily due to their detergent effect on membranes and induction of oxidative stress. Gangliosides can counteract these harmful effects by increasing the rigidity of the cytoplasmic membrane. Induction of haem oxygenase (HMOX) has been shown to protect the liver from increased oxidative stress. The aim of this study was to determine the changes in the synthesis and distribution of liver gangliosides following bile duct ligation (BDL), and to assess the effects of HMOX both on cholestatic liver injury and ganglioside metabolism. Compared to controls, BDL resulted in a significant increase in total as well as complex gangliosides and mRNA expression of corresponding glycosyltransferases ST3GalV, ST8SiaI and B3GalTIV. A marked shift of GM1 ganglioside from the intracellular compartment to the cytoplasmic membrane was observed following BDL. Induction of oxidative stress by HMOX inhibition resulted in a further increase of these changes, while HMOX induction prevented this effect. Compared to BDL alone, HMOX inhibition in combination with BDL significantly increased the amount of bile infarcts, while HMOX activation decreased ductular proliferation. We have demonstrated that cholestasis is accompanied by significant changes in the distribution and synthesis of liver gangliosides. HMOX induction results in attenuation of the cholestatic pattern of liver gangliosides, while HMOX inhibition leads to the opposite effect.

Heme oxygenase is not involved in the anti-proliferative effects of statins on pancreatic cancer cells.

BACKGROUND: Pancreatic cancer is recognized as one of the most fatal tumors due to its aggressiveness and resistance to therapy. Statins were previously shown to inhibit the proliferation of cancer cells via various signaling pathways. In healthy tissues, statins activate the heme oxygenase pathway, nevertheless the role of heme oxygenase in pancreatic cancer is still controversial. The aim of this study was to evaluate, whether anti-proliferative effects of statins in pancreatic cancer cells are mediated via the heme oxygenase pathway. METHODS: In vitro effects of various statins and hemin, a heme oxygenase inducer, on cell proliferation were evaluated in PA-TU-8902, MiaPaCa-2 and BxPC-3 human pancreatic cancer cell lines. The effect of statins on heme oxygenase activity was assessed and heme oxygenase-silenced cells were used for pancreatic cancer cell proliferation studies. Cell death rate and reactive oxygen species production were measured in PA-TU-8902 cells, followed by evaluation of the effect of cerivastatin on GFP-K-Ras trafficking and expression of markers of invasiveness, osteopontin (SPP1) and SOX2. RESULTS: While simvastatin and cerivastatin displayed major anti-proliferative properties in all cell lines tested, pravastatin did not affect the cell growth at all. Strong anti-proliferative effect was observed also for hemin. Co-treatment of cerivastatin and hemin increased anti-proliferative potential of these agents, via increased production of reactive oxygen species and cell death compared to individual treatment. Heme oxygenase silencing did not prevent pancreatic cancer cells from the tumor-suppressive effect of cerivastatin or hemin. Cerivastatin, but not pravastatin, protected Ras protein from trafficking to the cell membrane and significantly reduced expressions of SPP1 (p < 0.05) and SOX2 (p < 0.01). CONCLUSIONS: Anti-proliferative effects of statins and hemin on human pancreatic cancer cell lines do not seem to be related to the heme oxygenase pathway. While hemin triggers reactive oxygen species-induced cell death, cerivastatin targets Ras protein trafficking and affects markers of invasiveness.

The effect of heme oxygenase on ganglioside redistribution within hepatocytes in experimental estrogen-induced cholestasis.

Cholestasis is characterized by the elevation of serum total bile acids (TBA), which leads to the production of both free radicals and oxidative stress. Although they do not share the same mechanisms, membrane glycosphingolipids (GSL) and the antioxidant enzyme heme oxygenase-1 (HMOX1) both act against the pro-oxidative effect of TBA. The aim of the study was to assess the role of HMOX on GSL redistribution and composition within hepatocytes in the rat model of estrogen-induced cholestasis. Compared to the controls, an increase of total gangliosides in the liver homogenates of the cholestatic group (P=0.001) was detected; further, it paralleled along with the activation of their biosynthetic b-branch pathway (P<0.01). These effects were partially prevented by HMOX activation. Cholestasis was accompanied by a redistribution of GM1 ganglioside from the cytoplasm to the sinusoids; while HMOX activation led to the retention of GM1 in the cytoplasm (P=0.014). Our study shows that estrogen-induced cholestasis is followed by changes in the synthesis and/or distribution of GSL. These changes are not only triggered by the detergent power of accumulated TBA, but also by their pro-oxidant action. Increases in the antioxidant defenses might represent an important supportive therapeutic measure for patients with cholestatic liver disease.

Protective effects of inhaled carbon monoxide in endotoxin-induced cholestasis is dependent on its kinetics.

Carbon monoxide (CO), a product of heme oxygenase (HMOX), has many beneficial biological functions and is a promising therapeutic agent for many pathological conditions. However, the kinetics of inhaled CO and its protective role in endotoxin-induced cholestasis is not fully known. Thus, our objective was to characterize the kinetics of inhaled CO and then investigate its use in early phase experimental endotoxin-induced cholestasis. Female Wistar rats were randomly divided into 4 groups: CON (control), LPS (lipopolysaccharide, 6 mg/kg), CO (250 ppm COx1h), and CO + LPS. Rats were sacrificed at 0-12 h after LPS administration. Tissues and blood were collected for liver injury markers and tissue CO distribution measurements. Livers were harvested for measurements of Hmox activity, Hmox1 mRNA expression, cytokines (IL10, IL6, TNF), and bile lipid and pigment transporters. Half-lives of CO in spleen, blood, heart, brain, kidney, liver, and lungs were 2.4 ± 1.5, 2.3 ± 0.8, 1.8 ± 1.6, 1.5 ± 1.2, 1.1 ± 1.1, 0.6 ± 0.3, 0.6 ± 0.2 h, respectively. CO treatment increased liver IL10 mRNA and decreased TNF expression 1 h after LPS treatment and prevented the down-regulation of bile acid and bilirubin hepatic transporters (Slc10a1, Abcb11, and Abcc2, p < 0.05), an effect closely related to the kinetics. The protective effect of CO against cholestatic liver injury persisted even 12 h after CO exposure, as shown by attenuation of serum cholestatic markers in CO-treated animals. CO exposure substantially attenuated endotoxin-induced cholestatic liver injury and was directly related to the kinetics of inhaled CO. This data underscores the importance of the kinetics of inhaled CO for the proper design of experimental and clinical studies of using CO as a treatment strategy.

[Acute myocardial infarction in young patients--severe failures in the system of acute and secondary care]. / Akutní infarkt myokardu u mladých nemocných - závazné nedostatky v systému akutní a následné péce.

INTRODUCTION: The incidence of cardiovascular (CV) diseases and acute myocardial infarction (AMI) in Czech Republic is de-clining. In spite of this in a proportion of patients AMI occurs in young age. The aim of our project was to assess the character of risk factors, precipitating diseases and the quality of care in young AMI survivors. METHODS: We included 132 patients (97 men and 35 women) in whom AIM with ST elevations occurred before age of 45 years in men and age of 50 years in women. Several results were compared to a control group composed of 84 healthy volunteers of comparable age. We assessed the course of the disease, extent of coronary involvement, subsequent therapy and control of risk factors after 3 years from the index event. RESULTS: Smoking represented the main risk factor - 85% patents were active smokers at the time of AMI and 9% were former smokers, 64% patients had a positive family history of CV disease. We found a higher prevalence of dyslipidemia history in men. In spite of high rate of statin use, laboratory examination during follow-up revealed higher triglyceride values and low levels of HDL-cholesterol in both genders. All together 23% of patients had a history of provoking underlying disease or precipitating factors (inflammatory diseases, malignancies, combined thrombophilias, drug abuse). In total 95% of patients underwent coronary angiography during the acute phase of AMI, the median time from pain onset to intervention was 9 hours. Most patients had single vessel disease, 14% had even coronary angiogram without clinically significant stenosis. The subsequent care was satisfactory concerning the rate of drug prescriptions. However, target lipid values were not reached in 78% patients and blood pressure targets in 37%. CONCLUSIONS: In patients who suffered AMI in young age, risk factors are dominated by smoking and positive family history of CV diseases. One fifth of patients suffer from other underlying disease (inflammatory disease, malignancies, combined thrombophilia) or have another precipitating factor (febrile disease, drug abuse). The acute care seems unsatisfactory due to late arrival of most patients to catheterization laboratories (underestimation of the disease, incorrect initial diagnosis). Subsequent therapy is well composed but lacks in intensity.

Association of systemic lupus erythematosus with low serum bilirubin levels.

OBJECTIVE: Systemic lupus erythematosus (SLE) is accompanied by severe oxidative stress. Bilirubin has been reported as a strong negative predictor of oxidative stress-mediated diseases, such as atherosclerosis. The objective of our study was to evaluate the association between serum bilirubin levels and SLE manifestation. METHODS: The study was performed with 259 SLE patients, diagnosed according to American Rheumatism Association (ARA) criteria. A subset of these patients, having normal hepatic function (n = 218, mean age 39.5 years), was studied in greater detail to eliminate the possible confounding effects of any underlying or drug-induced liver disease on the serum bilirubin levels. Age-matched healthy subjects (n = 180) served as the control group. A standard biochemical and immunological work-up was performed on all subjects. RESULTS: Compared to the controls, substantially lower levels of serum bilirubin were detected in SLE patients (p < 10⁻5); these were inversely correlated with disease activity and extent (p < 0.05). Furthermore, each 1 µmol/L decrease in serum bilirubin was associated with a 37% increase in the odds for a positive SLE status [odds ratio (OR) 1.37, 95% confidence interval (CI) 1.28-1.47, p < 10⁻5]. Simultaneously, the odds of unconjugated hyperbilirubinaemia (a phenotypic sign of Gilbert's syndrome) were more than four times lower in SLE patients (OR 0.235, 95% CI 0.072-0.764, p = 0.016). CONCLUSION: Low serum bilirubin represented a strong predictor of the manifestation of SLE symptoms. The most likely explanation for this finding is the increased consumption of bilirubin due to the severe oxidative stress accompanying SLE. Subjects with higher serum bilirubin levels, such as those with Gilbert's syndrome, might be protected from the development of SLE.

Histochemical detection of GM1 ganglioside using cholera toxin-B subunit. Evaluation of critical factors optimal for in situ detection with special emphasis to acetone pre-extraction.

A comparison of histochemical detection of GM1 ganglioside in cryostat sections using cholera toxin B-subunit after fixation with 4% formaldehyde and dry acetone gave tissue-dependent results. In the liver no pre-treatment showed detectable differences related to GM1 reaction products, while studies in the brain showed the superiority of acetone pre-extraction (followed by formaldehyde), which yielded sharper images compared with the diffuse, blurred staining pattern associated with formaldehyde. Therefore, the aim of our study was to define the optimal conditions for the GM1 detection using cholera toxin B-subunit. Ganglioside extractability with acetone, the ever neglected topic, was tested comparing anhydrous acetone with acetone containing admixture of water. TLC analysis of acetone extractable GM1 ganglioside from liver sections did not exceed 2% of the total GM1 ganglioside content using anhydrous acetone at -20 degrees C, and 4% at room temperature. The loss increased to 30.5% using 9:1 acetone/water. Similarly, photometric analysis of lipid sialic acid, extracted from dried liver homogenates with anhydrous acetone, showed the loss of gangliosides into acetone 3.0 +/- 0.3% only. The loss from dried brain homogenate was 9.5 +/- 1.1%. Thus, anhydrous conditions (dry tissue samples and anhydrous acetone) are crucial factors for optimal in situ ganglioside detection using acetone pre-treatment. This ensures effective physical fixation, especially in tissues rich in polar lipids (precipitation, prevention of in situ diffusion), and removal of cholesterol, which can act as a hydrophobic blocking barrier.

[Nuclear factor kappa B in the treatment of inflammatory and tumor diseases]. / Nukleární faktor kappa B v lécbe zánetlivých a nádorových onemocnení.

Since its discovery in 1986 nuclear factor kappa B attracted attention of scientists all over the world. Intensive research has proved its indisputable role in pathogenesis of particularly inflammatory and tumor diseases and revealed many possibilities in the modulation of its function. For some of the modulators distinct therapeutic effects have been proved in in vitro and in vivo studies or even in the clinical trials, some of them are still to be tested. One may expect wide use of different inhibitors or modulators of nuclear factor kappa B in various indications, which will markedly enhance the therapeutic effect.

[Gilbert's syndrome--myths and reality]. / Gilbertuv syndrom--mýty a realita.

Gilbert's syndrome is defined as a hereditary, mild, chronic, unconjugated hyperbilirubinemia occurring in the absence of overt hemolysis or any other evidence of liver disease. It is caused by a mutation of the specific UDP glucuronosyl transferase conjugating bilirubin with glucuronic acid resulting in a reduced activity of this enzyme. Gilbert's syndrome is considered as a rather benign disorder without necessity of any therapeutic intervention. It is therefore crucial to establish a correct diagnosis and differentiate this syndrome from serious disorders of the liver tissue. In recent years strong antioxidant effects of bilirubin were demonstrated in numerous studies and the protective role of hyperbilirubinemia in the pathogenesis of various oxidative stress-mediated diseases was suggested. Gilbert's syndrome and its relationship to associated disorders such as hemolysis, pigment cholelithiasis, neonatal jaundice, schizophrenia and drug interactions are also being discussed.

[New views on immunopathology of viral hepatitis B and C]. / Nové pohledy na imunopatologii virových hepatitid B a C.

The interaction of non-cythopatic, hepatotropic viruses of hepatitis B and C with the host's immune system plays a critical role in determining the viral clearance and it contributes to the liver damage. The initial line of defence is antigen non-specific and is mediated by natural killer cells and macrophages. Simultaneously, virus-specific immunity is induced by professional antigen presenting cells that process and present viral antigens to T and B lymphocytes in the regional lymph nodes. Thereafter, viral specific T helper cells are activated and these cells initiate the anti-viral immune responses of B and CTL lymphocytes. Early, multispecific T cell responses are associated with viral clearance, whereas the imbalance of viral specific Th1 and Th2 lymphocytes plays a crucial role in the viral persistence. The imbalance of viral specific Th1 and Th2 lymphocytes leads to inadequate activation of antigen specific CTL cells. After recognition of viral antigens, T helper lymphocytes are differentiated to Th1 and Th2 cells according to the type of secreted cytokines. Th1 cells produce cytokines: interleukin-2, IFN-gamma, TNF-alpha, which are responsible for effective activation of CTL cells. In contrast, interleukin-4, interleukin-5 and interleukin-10 are secreted by Th2 cells, which are involved in activation of B lymphocytes and in production of neutralizing antibodies. These finding suggests that the viral clearance is associated with the early development and adequate mounting of the anti-viral multispecific immune responses of T helper and cytotoxic T lymphocytes.

[CEACAM1--a less well-known member of the family of carcinoembryonic antigens]. / CEACAM1--méne známý clen rodiny karcinoembryonálního antigenu.

CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule 1) is a transmembrane glycoprotein belonging to the carcinoembryonic antigen (CEA) family and immunoglobulin superfamily. It is localized mainly in the apical domains of polarized epithelia, leukocytes and endothelia. With respect to this wide tissue distribution the research is focused on the study of its biological functions. Structural and functional analyses show that the extracellular domain of CEACAM1 participates in homotypic and heterotypic adhesion, whereas the cytoplasmic domain takes part in cell growth inhibition and signal transduction. Whereas CEA is highly expressed in adenocarcinomas, CEACAM1 expression is down regulated in many tumors and its tumor-supressive function was confirmed. CEACAM1 also takes part in insulin metabolism, acts as a promotor of cholesterol crystallization and serves as a binding receptor for certain bacterial strains in humans as well as hepatitis virus in mice.

[Statins in the treatment of tumors. Fiction or a new therapeutic approach?]. / Statiny v lécbe nádorových onemocnení. Fikce nebo nový terapeutický prístup?

HMG-CoA reductase inhibitors (statins) belong to the key hypocholesterolemic drugs. Besides this very important function, several others have been recently demonstrated such as the inhibition of atherogenous plaque formation, platelet aggregation, or improvement of endothelial function and fibrinolytic activity, or even the direct protective effects of statins on the mortality of acute myocardial infarction. Aside from the major interest of both the medical community and pharmaceutical companies remain the very important anti-tumor effects of this group of drugs. As based on recent medical research, inhibition of HMG-CoA reductase, the key enzyme in the cholesterol biosynthesis, brings about depletion of several intermediates. The most important one seems to be farnesyl pyrophosphate, which has a very important role in the cell signaling affecting apoptosis. The aim of the survey is to summarize present knowledge in this medical field and to demonstrate the enormous curative potential of this group of drugs.

Carcinoembryonic antigen-related cell adhesion molecule 1 is the 85-kilodalton pronase-resistant biliary glycoprotein in the cholesterol crystallization promoting low density protein-lipid complex.

A pronase resistant 85-kd glycoprotein in the Concanavalin A-binding fraction (CABF) of biliary glycoproteins has been reported to act as a promotor of cholesterol crystallization. De Bruijn et al. (Gastroenterology 1996;110:1936-1944) found this protein in a low-density protein-lipid complex (LDP) with potent cholesterol crystallization promoting activity. This study identifies and characterizes this protein. An LDP was prepared from CABF by discontinuous gradient ultracentrifugation. Proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), blotting and immunochemical staining with anti-carcinoembryonic antigen, CEA-related adhesion molecule 1 (CEACAM1) cross-reacting antibodies. Biliary concentrations of CEA cross-reacting proteins were determined in patients with and without gallstones. Two isoforms of CEACAM1 (85- and 115-kd bands), CEA and 2 CEA cross-reacting protein bands of 40 and 50 kd were found in human bile. All bands were also present in CABF, but only a subfraction of the 85-kd band found in the LDP was resistant to digestion with pronase. CEACAM1-85 exhibited potent cholesterol crystallization promoting activity in vitro and accounted for most of the activity in CABF. Total CEA cross-reacting protein concentrations were the same in gallbladder biles from patients with cholesterol and pigment gallstones but only half of those in biles from nongallstone subjects. In conclusion, we have identified the protein component of the cholesterol crystallization promoting LDP to be CEACAM1-85.

Immunoaffinity isolation of CEACAM1 on hydrazide-derivatized cellulose with immobilized monoclonal anti-CEA antibody.

Carcinoembryonic cell adhesion molecule 1 (CEACAM1) is a human membrane glycoprotein belonging to the carcinoembryonic antigen (CEA) family and to the immunoglobulin superfamily. It is expressed in apical membranes of many epithelial cells in gastrointestinal and urogenital tract and also in granulocytes and lymphocytes, and its biological effect in human tissues has recently been discussed in literature. The purpose of this study was to isolate CEACAM1 glycoprotein from bile and characterize its purity and recovery which has not been described before. Affinity chromatography of CEACAM1 on hydrazide-activated cellulose with immobilized monoclonal anti-CEA F34-187 antibody is described. The immunoglobulin carbohydrate moiety was oxidized by periodate and then bound to hydrazide-activated matrix. Crude protein fraction from bile was applied on the affinity column and after extensive washing of non-bound proteins CEACAM1 was eluted with 6 M guanidine-HCl. A single immunopositive 85 kDa band was detected on Western blots with anti-CEA antibody after SDS-PAGE. We found out that CEACAM1 was not stainable with any common method of protein staining and the only non-specific method which could detect the 85 kDa band was a lectin staining.