Gene expression changes in cancellous bone of type 2 diabetics: a biomolecular basis for diabetic bone disease.

PURPOSE: Diabetes mellitus type 2 (2DM) is associated with altered bone quality. In order to analyze associated changes on a molecular level, we investigated the gene expression of key factors of osteoblast metabolism in type 2 diabetics. METHODS: Total mRNA and protein of bone samples from 2DM patients and non-diabetic patients were isolated, and subsequently, reverse transcription polymerase chain reaction (RT-PCR) or Western blot was performed. Furthermore, pro- and anti-inflammatory serum cytokine levels were determined using a cytokine array. RESULTS: Expression of runt-related transcription factor 2 (RUNX2) was increased by 53 %. Expression of the bone sialoproteins, secreted phosphoprotein 1 (SPP1; osteopontin), and integrin-binding sialoprotein (IBSP), was elevated by more than 50 %, and activating transcription factor 4 (ATF4) expression was 13 % lower in the investigated diabetes group compared to the control group. Similarly, the expression of versican (VCAN) and decorin (DCN) was upregulated twofold in the diabetic group. At the same time, 2DM patients and controls show alterations in pro- and anti-inflammatory cytokine levels in the serum. CONCLUSIONS: This study identifies considerable changes in the expression of transcription factors and extracellular matrix (ECM) components of bone in 2DM patients. Furthermore, the analysis of key differentiation factors of osteoblasts revealed significant alterations in gene expression of these factors, which may contribute to the dysregulation of energy metabolism in 2DM.

Decrease of global methylation improves significantly hepatic differentiation of Ad-MSCs: possible future application for urea detoxification.

Hepatocyte transplantation is considered to be an alternative to orthotopic liver transplantation. Cells can be used to bridge patients waiting for a donor organ, decrease mortality in acute liver failure, and support metabolic liver diseases. The limited availability of primary human hepatocytes for such applications has led to the generation of alternative hepatocyte-like cells from various adult stem or precursor cells. The aim of this study was to generate hepatocyte-like cells from adipose-derived mesenchymal stem cells (Ad-MSCs) for clinical applications, which are available "off the shelf." Epigenetic changes in hepatocyte-like cells were induced by 5-azacytidine, which, in combination with other supplements, leads to significantly improved metabolic and enzymatic activities compared to nontreated cells. Cells with sufficient hepatic features were generated with a four-step protocol: 5-azacytidine (step 1); epidermal growth factor (step 2); fibroblast growth factor-4, dexamethasone, insulin-transferrin-sodium-selenite, and nicotinamide (step 3); and hepatocyte growth factor, dexamethasone, insulin-transferrin-sodium-selenite, and nicotinamide (step 4). Generated differentiated cells had higher phase I (CYP1A1/2, CYP2E1, CYP2B6, CYP3A4) and phase II activities compared to the undifferentiated cells. A strong expression of CYP3A7 and a weak expression of 3A4, as well as the important detoxification markers α-fetoprotein and albumin, could also be detected at the mRNA level. Importantly, urea metabolism (basal, NH4-stimulated, NH4- and ornithine-stimulated) was comparable to freshly isolated human hepatocytes, and unlike cryopreserved human hepatocytes, this activity was maintained after 6 months of cryopreservation. These findings suggest that these cells may be suitable for clinical application, especially for treatment of urea cycle disorders.

Differential effects of clinically used derivatives and metabolites of artemisinin in the activation of constitutive androstane receptor isoforms.

BACKGROUND AND PURPOSE: Widespread resistance to antimalarial drugs requires combination therapies with increasing risk of pharmacokinetic drug-drug interactions. Here, we explore the capacity of antimalarial drugs to induce drug metabolism via activation of constitutive androstane receptors (CAR) by ligand binding. EXPERIMENTAL APPROACH: A total of 21 selected antimalarials and 11 major metabolites were screened for binding to CAR isoforms using cellular and in vitro CAR-coactivator interaction assays, combined with in silico molecular docking. Identified ligands were further characterized by cell-based assays and primary human hepatocytes were used to elucidate induction of gene expression. KEY RESULTS: Only two artemisinin derivatives arteether and artemether, the metabolite deoxyartemisinin and artemisinin itself demonstrated agonist binding to the major isoforms CAR1 and CAR3, while arteether and artemether were also inverse agonists of CAR2. Dihydroartemisinin and artesunate acted as weak inverse agonists of CAR1. While arteether showed the highest activities in vitro, it was less active than artemisinin in inducing hepatic CYP3A4 gene expression in hepatocytes. CONCLUSIONS AND IMPLICATIONS: Artemisinin derivatives and metabolites differentially affect the activities of CAR isoforms and of the pregnane X receptor (PXR). This negates a common effect of these drugs on CAR/PXR-dependent induction of drug metabolism and further provides an explanation for artemisinin consistently inducing cytochrome P450 genes in vivo, whereas arteether and artemether do not. All these drugs are metabolized very rapidly, but only artemisinin is converted to an enzyme-inducing metabolite. For better understanding of pharmacokinetic drug-drug interaction possibilities, the inducing properties of artemisinin metabolites should be considered.

Superior antitumoral activity of dimerized targeted single-chain TRAIL fusion proteins under retention of tumor selectivity.

Although targeting of the death receptors (DRs) DR4 and DR5 still appears a suitable antitumoral strategy, the limited clinical responses to recombinant soluble TNF-related apoptosis inducing ligand (TRAIL) necessitate novel reagents with improved apoptotic activity/tumor selectivity. Apoptosis induction by a single-chain TRAIL (scTRAIL) molecule could be enhanced >10-fold by generation of epidermal growth factor receptor (EGFR)-specific scFv-scTRAIL fusion proteins. By forcing dimerization of scFv-scTRAIL based on scFv linker modification, we obtained a targeted scTRAIL composed predominantly of dimers (Db-scTRAIL), exceeding the activity of nontargeted scTRAIL ∼100-fold on Huh-7 hepatocellular and Colo205 colon carcinoma cells. Increased activity of Db-scTRAIL was also demonstrated on target-negative cells, suggesting that, in addition to targeting, oligomerization equivalent to an at least dimeric assembly of standard TRAIL per se enhances apoptosis signaling. In the presence of apoptosis sensitizers, such as the proteasomal inhibitor bortezomib, Db-scTRAIL was effective at picomolar concentrations in vitro (EC(50) ∼2 × 10(-12) M). Importantly, in vivo, Db-scTRAIL was well tolerated and displayed superior antitumoral activity in mouse xenograft (Colo205) tumor models. Our results show that both targeting and controlled dimerization of scTRAIL fusion proteins provides a strategy to enforce apoptosis induction, together with retained tumor selectivity and good in vivo tolerance.

Effects of atorvastatin metabolites on induction of drug-metabolizing enzymes and membrane transporters through human pregnane X receptor.

BACKGROUND AND PURPOSE: Atorvastatin metabolites differ in their potential for drug interaction because of differential inhibition of drug-metabolizing enzymes and transporters. We here investigate whether they exert differential effects on the induction of these genes via activation of pregnane X receptor (PXR) and constitutive androstane receptor (CAR). EXPERIMENTAL APPROACH: Ligand binding to PXR or CAR was analysed by mammalian two-hybrid assembly and promoter/reporter gene assays. Additionally, surface plasmon resonance was used to analyse ligand binding to CAR. Primary human hepatocytes were treated with atorvastatin metabolites, and mRNA and protein expression of PXR-regulated genes was measured. Two-hybrid co-activator interaction and co-repressor release assays were utilized to elucidate the molecular mechanism of PXR activation. KEY RESULTS: All atorvastatin metabolites induced the assembly of PXR and activated CYP3A4 promoter activity. Ligand binding to CAR could not be proven. In primary human hepatocytes, the para-hydroxy metabolite markedly reduced or abolished induction of cytochrome P450 and transporter genes. While significant differences in co-activator recruitment were not observed, para-hydroxy atorvastatin demonstrated only 50% release of co-repressors. CONCLUSIONS AND IMPLICATIONS: Atorvastatin metabolites are ligands of PXR but not of CAR. Atorvastatin metabolites demonstrate differential induction of PXR target genes, which results from impaired release of co-repressors. Consequently, the properties of drug metabolites have to be taken into account when analysing PXR-dependent induction of drug metabolism and transport. The drug interaction potential of the active metabolite, para-hydroxy atorvastatin, might be lower than that of the parent compound.

Further characterization of autologous NeoHepatocytes for in vitro toxicity testing.

Gold standard for in vitro toxicity tests and drug screenings is primary human hepatocytes (hHeps). Because of their limited availability efforts have been made to provide alternatives, e.g., monocyte-derived NeoHepatocytes. In the past years it has been critically discussed if gaining hepatocyte features is associated with trans-differentiation of monocytes or their activation towards a macrophage phenotype. Generating NeoHepatocytes in the presence of six different human AB sera, fetal calf serum (FCS) or autologous serum showed that yield and quality of NeoHepatocytes is inversely correlated to macrophage activation. Using autologous serum constantly the highest amount of cells with the best metabolic capacity was obtained. Focus of this study was to further analyze bio-transformation capacity of the optimized NeoHepatocytes for use as in vitro toxicity test-system. Treatment of the optimized NeoHepatocytes with two different pro-teratogenic substances with corresponding metabolites and eight known hepatotoxins showed comparable toxicity to hHeps. Bio-transformation rates, assessed by testosterone metabolism, were comparable in both cell types. Our data reveal that use of autologous serum reduced macrophage activation which improved yield and function of NeoHepatocytes resulting in bio-transformation and toxicity profiles comparable to hHeps. Thus, their easy accessibility makes them an ideal candidate for in vitro toxicity studies.

Autologous serum improves yield and metabolic capacity of monocyte-derived hepatocyte-like cells: possible implication for cell transplantation.

Hepatocyte-transplantation is a therapeutic approach for diverse acute and chronic liver diseases. As availability of primary cells is limited, there is an increasing demand for hepatocyte-like cells (e.g., neohepatocytes generated from peripheral blood monocytes). The aim of this study was to evaluate the effects of six different human AB sera, fetal calf serum, or autologous serum on production of neohepatocytes. The yield and quality of neohepatocytes varied considerably depending on the different sera. Using autologous sera for the whole production process we constantly generated the highest amount of cells with the highest metabolic activity for phase I (e.g., CYP1A1/2, CYP3A4) and phase II enzymes (e.g., glutathione-S-transferase). Moreover, similar effects were seen examining glucose and urea metabolism. Especially, glucose-6-phosphatase and PAS staining showed distinct serum-dependent differences. The role of macrophage activation was investigated by measuring the secretion of TNF-α, TGF-ß, and RANKL, MMP activity, as well as mRNA levels of different interleukins in programmable cells of monocytic origin (PCMO). Our data clearly demonstrate that the use of autologous serum reduced initial macrophage activation in PCMOs and subsequently improved both yield and function of differentiated neohepatocytes. The autologous approach presented here might also be useful in other stem cell preparation processes where cell activation during generation shall be kept to a minimum.

Protective role of HO-1 for alcohol-dependent liver damage.

BACKGROUND/AIMS: Alcoholic liver disease is continuously increasing in developed countries being a leading cause of death worldwide. Chronic ethanol consumption induces oxidative stress by accumulation of reactive oxygen intermediates (ROI) while reducing the cellular antioxidant defense. Induction of heme oxygenase-1 (HO-1) may protect primary human hepatocytes (hHeps) from such damage. Thus, the aim of this study was to investigate the potential of polyphenols to protect hHeps from ethanol-dependent oxidative damage. METHODS: hHeps were isolated by collagenase perfusion. ROI and cellular glutathione (GSH) were measured by fluorescent-based assays. Cellular damage was determined by lactate dehydrogenase (LDH) leakage and staining for apoptosis and necrosis. Nuclear translocation of Nrf2 and HO-1 expression were analyzed by Western blot. RESULTS: Ethanol and TGF-ß rapidly increase ROI and reduce GSH in hHeps, causing apoptosis with a release of approximately 40% total LDH after 72 h. Similar to incubation with hemin preincubation and co-incubation of cells with nifedipine, verapamil and quercetin significantly reduce oxidative stress and resulting cellular damage, in a dose-dependent manner, by initiating nuclear translocation of Nrf2 which in turn induces HO-1 under the control of p38 and ERK. Blocking of HO-1 activity with ZNPP9 reverses the protective effect of all three substances. CONCLUSION: Our results suggest that increasing HO-1 activity in hHeps protects them from oxidative stress-dependent damage. As polyphenols have great potential to induce HO-1 expression, they may play an important role for future therapeutic strategies to protect liver from oxidative stress-dependent damage observed during chronic alcohol consumption.

Intrasplenic or subperitoneal hepatocyte transplantation to increase survival after surgically induced hepatic failure?

BACKGROUND: As a basis for future clinical questions, we evaluated the efficacy of hepatocyte transplantation in a surgical model using a subperitoneal or intrasplenic approach for cell implantation. METHODS: In rats, acute liver failure was induced by subtotal hepatectomy. Series of allogenic hepatocyte transplantations were performed by varying cell number, site, and sequence of cell transplantation. RESULTS: Following subperitoneal or intrasplenic cell implantation subsequent to liver surgery, no survival benefit was achieved when compared to the control groups. However, intrasplenic cell implantation 24 h prior to liver surgery revealed a statistically significantly higher animal survival (72 vs. 29%). CONCLUSION: According to our experience, both timing and site of cell implantation played an important role in hepatocyte transplantation. Intrasplenic hepatocyte transplantation 1 day before liver surgery showed the best results in terms of survival. Consequently, we were able to establish a model of hepatocyte transplantation which may be the basis for further investigations evaluating potential treatment modalities to overcome deleterious postoperative liver insufficiency.

Cobalt-protoporphyrin induced heme oxygenase overexpression and its impact on liver regeneration.

Cobalt-protoporphyrin (CoPP)-dependent induction of heme oxygenase (HO)-1 has been shown to protect from ischemia-reperfusion injury, which remains a major source of graft loss after liver transplantation. The impact of HO-1 on liver regeneration, especially in reduced-size grafts, has not yet been evaluated. Using an experimental model, we investigated HO-1 induction by CoPP treatment on postoperative recovery of ischemically injured livers following partial (70%) hepatectomy. Wistar rats underwent partial hepatectomy under temporary inflow occlusion (30 minutes). One group of animals received CoPP (5 mg/kg body weight i.p.) 24 hours prior to surgery to induce high levels of HO-1 at the time of surgery, and the second group served as nontreated controls. At postoperative days 1, 4, 7, and 10, animals were exsanguinated, and blood and liver samples were stored for enzymatic (serum AST and ALT levels) and histologic (mitotic index) analyses (n = 5 each day). Additionally, postoperative body weight and weight of the remnant liver were measured. Although serum AST and ALT levels as well as remnant liver weight were comparable between both groups, CoPP-treated animals recovered from surgery more quickly as indicated by postoperative body weight. Moreover, the number of mitotic cells was significantly increased in this group at day 1 (33 +/- 5 versus 20 +/- 5 per 2000 hepatocytes) as compared with nontreated animals. Liver regeneration of ischemically injured livers following partial hepatectomy was improved by HO-1 overexpression following preoperative CoPP administration. Thus, it is conceivable that prevention of ischemia-reperfusion injury by HO-1 overexpression also might be beneficial for reduced-size liver grafts without affecting their proliferative capacity.

Effects on protein and mRNA expression levels of p53 induced by fluoride in human embryonic hepatocytes.

We investigated the effects of protein and mRNA expression levels on p53 induced by fluoride in human embryo hepatocyte L-02 cells. The protein and mRNA levels of p53 in L-02 cells were measured after in vitro cultured L-02 was exposed to sodium fluoride at different doses (40, 80, and 160 microg/ml) for 24 h. The results showed that the cell survival rate of L-02 cells in the high dose fluoride group was significantly lower than that of the control group. The protein expression levels of p53 in the middle and high dose fluoride group were significantly higher than in the control group and elevated with increasing fluoride concentration. The mRNA expression levels of p53 in the fluoride groups were markedly higher than in the control group. The mRNA expression level of p53 in the high dose fluoride group was however lower compared to the middle dose fluoride group, but similar to the low dose fluoride group. These finding suggest that fluoride can decrease the L-02 cells survival rate and induce protein and mRNA expressions of p53; however, there is no consistency between the protein expression level of p53 and the mRNA expression level.

Changes in serum levels of growth factors in healthy individuals after living related liver donation.

INTRODUCTION: To obtain better insight into the kinetics of hepatic growth factors following partial hepatectomy for living related liver donation, we investigated the postoperative changes in serum levels of hepatocyte growth factor (HGF), epidermal growth factor (EGF), vascular epidermal growth factor (VEGF), and transforming growth factor-alpha (TGF-alpha). PATIENTS AND METHODS: Eighteen healthy donors undergoing right hepatectomy for living related donation were enrolled in this study. Serum levels of HGF, EGF, VEGF, and TGF-alpha were measured using enzyme-linked immunosorbent assay kits before surgery, at 2 hours after resection, and daily during 5 days postoperatively. RESULTS: Mean preoperative HGF serum levels in healthy adults were 778 +/- 64 pg/mL. Within 2 hours after operation, they significantly increased to 9608 +/- 3111 pg/mL afterward decreasing to 2726 +/- 241 at day 1 and 2283 +/- 250 pg/mL at day 2. Hereafter HGF serum levels stabilized at increased levels until day 5 (2109 +/- 138, 2047 +/- 219, 2283 +/- 336 pg/mL, respectively). At all time points, the differences between pre- and postoperative HGF levels were significant (P < .01). In contrast, VEGF and EGF serum levels showed no significant differences between pre- and postoperative levels at all time points. TGF-alpha was not detected using a commercially available test with a detection limit of 10 ng/mL, suggesting only low TGF-alpha serum levels following liver resection. CONCLUSION: Significantly increased HGF serum levels after hepatectomy demonstrate its crucial role among the other investigated growth factors in regeneration of the remnant liver tissue during the early period after the operation.

Effects of human hepatocyte growth factor on the proliferation of human hepatocytes and hepatocellular carcinoma cell lines.

BACKGROUND: Hepatocyte growth factor (HGF) has been suggested to initiate both hepatocyte and tumor cell proliferation after partial hepatectomy, thereby supporting local tumor recurrence. The aim of this study was to clarify the role of HGF in the regeneration of human hepatocyte and the growth of residual hepatocellular carcinoma cells after liver resection. PATIENTS/METHODS: 36 patients who underwent partial hepatectomy for hepatocellular carcinoma (HCC) or living liver donation have been analyzed for HGF serum levels at day -1 through day 5 following surgery using an enzyme-linked immunosorbent assay. Isolated human hepatocytes and HCC cell lines (Hep 3B, Hep G2) were treated either with recombinant human (rh)-HGF, or sera from the 36 patients in the presence or absence of anti-HGF in order to measure their proliferative capacity using (3)H-thymidine incorporation. RESULTS: Basal HGF levels were significantly higher in HCC than in healthy patients (1,573 +/- 131 vs. 778 +/- 64 pg/ml; p < 0.001), however, the postoperative rise of HGF in healthy patients was higher (9,608 +/- 3111 vs. 2,060 +/- 148 pg/ml) than in HCC patients. Incubation of human hepatocytes and Hep 3B cells with rh-HGF revealed a dose-dependent increase in DNA synthesis, while anti-HGF partially abolished this effect. Sera from normal and resected HCC patients stimulated DNA synthesis only in human hepatocytes, whereas it was inhibited in HCC cell lines. CONCLUSION: HGF plays an important role in hepatocyte proliferation but contrary to in vitro results, HGF does not play a major role for the progression of hepatocarcinoma cells in vivo.

Role of iron in tumor cell protection from the pro-apoptotic effect of nitric oxide.

F2The host defense against tumor cells is in part based upon the production of nitric oxide (NO) by activated macrophages. However, carcinogenesis may involve mechanisms that protect tumor cells from NO-mediated apoptosis. In the present study, we have assessed the effects of exogenous NO on the proliferation and survival of human liver (AKN-1), lung (A549), skin (HaCat), and pancreatic (Capan-2) tumor cell lines, compared with normal skin-derived epithelial cell cultures. Except to the HaCat cell line, all of the other human epithelioid cells were sensitive to the antiproliferation effect of S-nitroso-N-acetyl-penicillamine or Deta NONOate, whereas tumor cells had low if any response to sodium nitroprusside. Growth inhibition with exogenous NO correlated with increased apoptosis, but was not mediated by cyclic GMP, peroxynitrite generation, or poly(ADP-ribose) polymerase modulation, all of which involved in NO-mediated growth inhibition of normal skin-derived epithelial cell cultures. The simultaneous addition of iron-containing compounds protected tumor cells from NO-mediated growth inhibition and apoptosis. Intracellular iron quantification indicated that, as deferoxamine, exogenous NO significantly decreased intracellular ferric iron levels in tumor cells. Together, the current study reveals that intracellular iron elevation rescues tumor cells from NO-mediated iron depletion and subsequent growth inhibition and apoptosis.

Inhibition of nitric oxide synthesis by aminoguanidine increases intestinal damage in the acute phase of rat TNB-colitis.

The role of nitric oxide (NO) in the pathophysiology of inflammatory bowel diseases (IBD) is controversially discussed. The aim of the present study was to investigate the role of NO inhibition in the acute phase of rat 2,4,6-trinitrobenzenesulphonic acid (TNB)-colitis. To inhibit NO synthesis we used aminoguanidine (AG) as a selective inhibitor of inducible nitric oxide synthase (iNOS). TNB-colitis was induced in rats with and without pretreatment with AG (200 mg kg-1 body weight in the drinking water). The severity of colitis was observed over a period of 7 days. On days 1 and 2, AG reduced concentrations of plasma nitrate and nitrite as well as of portal 6-keto-prostaglandin 1alpha. AG pretreatment increased colonic damage and inflammatory response, assessed by colonic myeloperoxidase and serum lactate dehydrogenase activity, macroscopic damage score, tumour necrosis factor-alpha concentration in stool and colonic glutathione content. The AG-treated group showed a higher and prolonged nuclear factor kappaB (NF-kappaB)/Rel binding activity in the colon. We conclude that NOS inhibition by AG is not beneficial in acute intestinal inflammation. With regard to appropriate therapeutic strategies, NF-kappaB/Rel activation might be a more suitable target.

Modulation of endogenous nitric oxide synthase in experimental acute pancreatitis: role of anti-ICAM-1 and oxygen free radical scavengers.

OBJECTIVE: To evaluate, in an experimental model of acute pancreatitis, the impact of nitric oxide on the disease process and the interaction between nitric oxide and oxygen free radicals. SUMMARY BACKGROUND DATA: Nitric oxide and oxygen free radicals are involved in the pathophysiology of acute pancreatitis. It is well established that oxygen free radicals play an important role in the development of pancreatic cell damage and remote organ failure, but the impact of nitric oxide on the disease process and the interactions between the two radical species remain controversial. METHODS: Necrotizing pancreatitis (NP) was induced in Wistar rats by intraductal sodium taurocholate infusion after pretreatment with isotonic saline (NP-S), superoxide dismutase/catalase (NP-SOD/CAT), or an anti-ICAM-1 antibody (aICAM-1). Sham-operated rats received isotonic saline (SHX). After an observation period of 5 minutes and 24 hours, the pancreas was removed for microscopy, glutathione, and myeloperoxidase (MPO) analysis. The inducible NO synthase (NOS-2) was detected by Western blotting or RT-PCR. Serum was analyzed for nitrite/nitrate (NO2-/NO3-) and S-nitrosothioles (RSNO), while plasma was used to assay for trypsinogen activation peptides (TAP). RESULTS: NP-S animals showed a significant decrease in GSH levels after NP-induction as compared with animals under therapy. Increased MPO levels in the NP-S group were significantly reduced by aICAM-1 while SOD/CAT injection showed no changes. Serum NO-derivatives peaked at 12 hours while TAP levels had a maximum at 6 hours after NP induction, and were lower after aICAM-1 application SOD/CAT treatment increased both parameters. Extended acinar cell damage and inflammatory infiltrate developed in NP-S animals and was significantly improved by SOD/CAT and aICAM-1 treatment. RT-PCR and Western-blot analysis revealed NOS-2 expression in the NP-S group, which was reduced by radical scavengers and aICAM-1. CONCLUSION: Enhanced nitric oxide synthase expression and increased nitric oxide derivatives are found during severe acute pancreatitis. Oxygen free radicals and neutrophils seem to be potent and important regulation mechanisms for nitric oxide synthase activity and nitric oxide-mediated toxicity but imply only a secondary role for nitric oxide in the local pathologic mechanism of this disease.

Upregulation of intraepithelial lymphocyte (IEL) function in the small intestinal mucosa in sepsis.

Host defense mechanisms preventing bacterial invasion are particularly important in the gastrointestinal tract, since most gram-negative infections originate from there. Intraepithelial lymphocytes (IEL) seem to play an important role in this immune surveillance of the intestine, although their function in sepsis is not fully understood. To evaluate the characteristics of IEL in sepsis, C57BL/6 mice received a non-lethal dose of LPS and IEL were harvested at various time points thereafter. Although IEL displayed no phenotypic changes after endotoxemia, they displayed enhanced cytolytic activity and increased proliferation after LPS injection In addition, IEL from septic mice showed enhanced gamma interferon (IFN-gamma) production after LPS administration. The production of IFN-gamma may have induced the increased intestinal NOS-2 mRNA expression which was observed after endotoxemia. In conclusion, endotoxemia leads to functional activation of IEL without phenotypic changes. The activation of IEL and the subsequently increased NOS-2 expression may be important mechanisms in maintaining the mucosal barrier after sublethal LPS challenge.

Effects of hepatocellular iron imbalance on nitric oxide and reactive oxygen intermediates production in a model of sepsis.

BACKGROUND/AIMS: In mammals iron homeostasis is most important, as imbalance of iron such as iron overload may lead to severe diseases. Recently, it has been shown that the iron regulatory protein-1 is partially controlled by nitric oxide and reactive oxygen intermediates, molecules frequently seen in inflammatory events. The aim of the present study was to investigate the effects of impaired iron homeostasis on the interaction of nitric oxide, and reactive oxygen intermediate formation in hepatocytes in a model of acute inflammation. METHODS: Hepatocytes isolated from Corynebacterium parvum (C parvum)-injected rats were used to examine the formation of nitrogen and oxygen intermediates by iron deprivation and iron overload in the presence of lipopolysaccharide. In addition, we investigated the RNA binding and aconitase activity of iron regulatory protein-1. RESULTS: In the present study we show that iron overload in lipopolysaccharide-treated C. parvum-primed hepatocytes downregulated the RNA binding of iron regulatory protein-1 and aconitase activity. Subsequently, we observed a reduced formation of nitrite/nitrate and S-nitrosothiols but an increased production of reactive oxygen species, and hepatocellular damage. Moreover, the addition of iron to cell cultures caused a further increase in cellular damage, a drop in the cellular glutathione pool, and an increase in peroxynitrite and hydroxyl-like radicals. In contrast, addition of deferoxamine (an iron chelator) to lipopolysaccharide-treated C. parvum-primed hepatocytes protected cells by stabilizing the GSH content, maintaining the nitric oxide formation, and by reducing Fenton oxidants. CONCLUSIONS: Our results show that the antioxidative effects of iron chelators prevent the formation of toxic Fenton oxidants in severe inflammatory events, which should be considered in the treatment of disorders characterized by an iron imbalance.

Glutathione depletion causes cell growth inhibition and enhanced apoptosis in pancreatic cancer cells.

BACKGROUND: Recent studies have demonstrated that various tumors express enhanced levels of the radical scavenger glutathione (GSH). Moreover, there are grounds for claiming that GSH plays a crucial role in cell proliferation and tumor resistance. In the current study, we investigated the relation between cell growth and GSH levels in the pancreatic adenocarcinoma cell line, AsPC-1, and the significance of GSH in tumor resistance to chemotherapy. METHODS: Cell growth in AsPC-1 was initiated through transforming growth factor-alpha (TGF-alpha) or fetal calf serum (FCS). Then, cell cycle, cell proliferation, and cellular GSH content were analyzed at different times in the presence or absence of buthionine sulfoximine (BSO). The impact of GSH on chemotherapy-induced apoptosis was studied using 5-fluorouracil or melphalan in the presence or absence of BSO. Finally, we compared the GSH content of 15 pancreatic tumor specimens with 10 normal pancreatic tissue specimens. RESULTS: Analysis of GSH in pancreatic tissues demonstrated increased GSH levels in cancerous compared with normal tissue (17.5 +/- 2.3 vs. 8. 8 +/- 1.4 nmol/mg protein; P < 0.004). Incubation of AsPC-1 with TGF-alpha or FCS resulted in cell proliferation and cell cycle activity, whereas GSH content was not altered. Incubation of GSH-depleted cells with TGF-alpha did not stimulate cell growth. In addition, GSH-depletion resulted in an increased rate of apoptosis after melphalan (6.3 +/- 0.3 % vs. 11.2 +/- 0.3 %; P < 0.001), but not after 5-fluorouracil treatment. CONCLUSIONS: Taken together, our results show enhanced GSH levels in pancreatic carcinoma and an essential role of GSH in cell proliferation and in resistance of AsPC-1 cells. Therefore, GSH-depletion may improve the efficacy of adjuvant therapy in pancreatic carcinoma.