Prostaglandin E(1) protects human liver sinusoidal endothelial cell from apoptosis induced by hypoxia reoxygenation

Toxic responses of liver in Lateolabrax maculatus during hypoxia and re-oxygenation

Estuarine environmental have been reported to undergo significant fluctuations in oxygen concentrations with hypoxic conditions and subsequent re-oxygenation events being of significant concern for resident fish populations. In this study we assessed the toxicological effects of hypoxia and re-oxygenation on the liver of hypoxia-sensitive spotted sea bass (Lateolabrax maculatus) that were exposed to hypoxia (1.17 mg/L dissolved oxygen) for 12 h and then re-oxygenated for 12 h. The activities of glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase in serum significantly increased under hypoxia (p < 0.05) and continued to increase during re-oxygenation (p < 0.05), indicating that normal liver function might be disrupted by hypoxia and might become worse during re-oxygenation for 12h. Total protein, albumin, and globulin levels in serum decreased under hypoxia but began to return to normal during re-oxygenation, showing that protein synthesis in the liver decreased during hypoxia but could be restored by re-oxygenation. We also used RNA-Seq technology to identify changes in gene expression in the liver during hypoxia and re-oxygenation. Transcriptome sequencing revealed that the hypoxia-inducible factor (HIF-1) signaling pathway, apoptosis, and purine metabolism transcripts were significantly enriched under hypoxia and re-oxygenation conditions. A total of 15 and 16 apoptosis-related genes were induced by hypoxia and re-oxygenation stress, respectively. The apoptosis index increased from the normal to the hypoxic condition and was highest under re-oxygenation. Additionally, 19 and 29 genes, that are involved in purine metabolism in the liver of L. maculatus during hypoxia and re-oxygenation, respectively, were dysregulated. Unexpectedly, the serum uric acid level significantly increased during hypoxia and significantly decreased under re-oxygenation, indicating the presence of purine metabolic disorder in the liver of L. maculatus. These results illustrate that hypoxia poses a pronounced threat to hepatocyte function in L. maculatus and that liver damage is difficult to reverse with 12 h of re-oxygenation, and it may actually become worse when re-oxygenation is established.

Prostaglandin E1 protects cardiomyocytes against hypoxia-reperfusion induced injury via the miR-21-5p/FASLG axis

Background: Prostaglandin-E1 (PGE1) is a potent vasodilator with anti-inflammatory and antiplatelet effects. However, the mechanism by which PGE1 contributes to the amelioration of cardiac injury remains unclear.

Methods: The present study was designed to investigate how PGE1 protects against hypoxia/reoxygenation (H/R)-induced injuries by regulating microRNA-21-5p (miR-21-5p) and fas ligand (FASLG). Rat H9C2 cells and isolated primary cardiomyocytes were cultured under hypoxic conditions for 6 h (6H, hypoxia for 6 h), and reoxygenated for periods of 6 (6R, reoxygenation for 6 h), 12, and 24 h, respectively. Cells from the 6H/6R group were treated with various doses of PGE1; after which, their levels of viability and apoptosis were detected.

Results: The 6H/6R treatment regimen induced the maximum level of H9C2 cell apoptosis, which was accompanied by the highest levels of Bcl-2-associated X protein (Bax) and cleaved-caspase-3 expression and the lowest level of B-cell lymphoma 2 (Bcl-2) expression. Treatment with PGE1 significantly diminished the cell cytotoxicity and apoptosis induced by the 6H/6R regimen, and also decreased expression of IL-2, IL-6, P-p65, TNF-α, and cleaved-caspase-3. In addition, we proved that PGE1 up-regulated miR-21-5p expression in rat cardiomyocytes exposed to conditions that produce H/R injury. FASLG was a direct target of miR-21-5p, and PGE1 reduced the ability of H/R-injured rat cardiomyocytes to undergo apoptosis by affecting the miR-21-5p/FASLG axis. In addition, we proved that PGE1 could protect primary cardiomyocytes against H/R-induced injuries.

Conclusions: These results indicate that PGE1 exerts cardioprotective effects in H9C2 cells during H/R by regulating the miR-21-5p/FASLG axis.

Role of oxylipins generated from dietary PUFAs in the modulation of endothelial cell function

Oxylipins, which are circulating bioactive lipids generated from polyunsaturated fatty acids (PUFAs) by cyclooxygenase, lipooxygenase and cytochrome P450 enzymes, have diverse effects on endothelial cells. Although studies of the effects of oxylipins on endothelial cell function are accumulating, a review that provides a comprehensive compilation of current knowledge and recent advances in the context of vascular homeostasis is lacking. This is the first compilation of the various in vitro, ex vivo and in vivo reports to examine the effects and potential mechanisms of action of oxylipins on endothelial cells. The aggregate data indicate docosahexaenoic acid-derived oxylipins consistently show beneficial effects related to key endothelial cell functions, whereas oxylipins derived from other PUFAs exhibit both positive and negative effects. Furthermore, information is lacking for certain oxylipin classes, such as those derived from α-linolenic acid, which suggests additional studies are required to achieve a full understanding of how oxylipins affect endothelial cells.

New aspects of hepatic endothelial cells in physiology and nonalcoholic fatty liver disease

The liver is the central metabolic hub for carbohydrate, lipid, and protein metabolism. It is composed of four major types of cells, including hepatocytes, endothelial cells (ECs), Kupffer cells, and stellate cells. Hepatic ECs are highly heterogeneous in both mice and humans, representing the second largest population of cells in liver. The majority of them line hepatic sinusoids known as liver sinusoidal ECs (LSECs). The structure and biology of LSECs and their roles in physiology and liver disease were reviewed recently. Here, we do not give a comprehensive review of LSEC structure, function, or pathophysiology. Instead, we focus on the recent progress in LSEC research and other hepatic ECs in physiology and nonalcoholic fatty liver disease and other hepatic fibrosis-related conditions. We discuss several current areas of interest, including capillarization, scavenger function, autophagy, cellular senescence, paracrine effects, and mechanotransduction. In addition, we summarize the strengths and weaknesses of evidence for the potential role of endothelial-to-mesenchymal transition in liver fibrosis.

Effects of misoprostol treatment on doxorubicin induced renal injury in rats

We investigated the potential nephroprotective effects of misoprostol (MP) on doxorubicin (DOX) induced renal injury using histologic and biochemical assessment of rat kidneys. We used 21 male rats divided into three groups: group 1, control; group 2, DOX; group 3, DOX + MP. The control group was given 0.5 ml 0.9% NaCl and 1 ml 0.9% NaCl orally for 6 days. DOX was administered as a single dose of 20 mg/kg on day 3. MP was administered orally for 6 days. We found that treatment with MP decreased serum creatinine and blood urea nitrogen levels significantly. DOX increased the malondialdehyde level and decreased catalase, superoxide dismutase activities and glutathione level. These alterations were prevented in renal tissues by MP. MP also decreased NADPH oxidase-4 and caspase-3 levels. In the DOX + MP group, oxidative stress was decreased, antioxidant activity was increased and histopathological changes were reduced compared to the DOX group. Renal injury caused by DOX was attenuated by MP treatment owing to the antioxidative and anti-apoptotic effects of MP.

Protective role of misoprostol in prevention of gentamicin ototoxicity

OBJECTIVES

To demonstrate potential protective effect of misoprostol on cochlear toxicity caused by gentamicin with electrophysiological tests and histopathological studies.

MATERIALS AND METHODS

The study included 80 ears of 40 rats with normal hearing threshold and DPOAE value in both ears. Animals were assigned into 4 groups. The rats were randomized into 4 groups. Group I (n = 10): Gentamicin, Group II (n = 10): Gentamicin plus misoprostol, Group III (n = 10): Saline; Group IV (n = 10): Misoprostol. All drugs used in the study were given once daily for 15 days. DPOAE and ABR measurements were repeated after drug administration. Subsequently, the rats' cochleae were examined histopathologically. Baseline DPOAE and ABR values were compared to those obtained after drug exposure and cochlear toxicity was evaluated in electrophysiological manner.

RESULTS

When At baseline, there were no significant differences in DPOAE responses at frequencies of 1001, 1501, 2002, 3003, 4004, 6006 and 7996 Hz among groups. However In DPOAE test, statistically significant difference was observed between the pre-study basal values and post-study results in groups other than gentamicin + misoprostol group. Additionally, It was found that there was a significant difference in DPOAE response at frequency of 4004 Hz obtained at baseline and after drug exposure according to measurements of epithelial vacuolization in stria vascularis. While ABR threshold values were compared at baseline, there were no significant difference in ABR threshold values of left and right ear between groups. Histopathologically it was also found that there were significant differences measurements of epithelial vacuolization in stria vascularis and inflammation among groups (p < 0.05).

CONCLUSION

By these results, misoprostol, a potent antioxidant, has protective effect against cochlear damage, and that may be a safe alternative.

Role of matrix metalloproteinases in cholestasis and hepatic ischemia/reperfusion injury: A review

Matrix metalloproteinases (MMPs) are a family of proteases using zinc-dependent catalysis to break down extracellular matrix (ECM) components, allowing cell movement and tissue reorganization. Like many other proteases, MMPs are produced as zymogens, an inactive form, which are activated after their release from cells. Hepatic ischemia/reperfusion (I/R) is associated with MMP activation and release, with profound effects on tissue integrity: their inappropriate, prolonged or excessive expression has harmful consequences for the liver. Kupffer cells and hepatic stellate cells can secrete MMPs though sinusoidal endothelial cells are a further source of MMPs. After liver transplantation, biliary complications are mainly attributable to cholangiocytes, which, compared with hepatocytes, are particularly susceptible to injury and ultimately a major cause of increased graft dysfunction and patient morbidity. This paper focuses on liver I/R injury and cholestasis and reviews factors and mechanisms involved in MMP activation together with synthetic compounds used in their regulation. In this respect, recent data have demonstrated that the role of MMPs during I/R may go beyond the mere destruction of the ECM and may be much more complex than previously thought. We thus discuss the role of MMPs as an important factor in cholestasis associated with I/R injury.

New insights into host-pathogen interactions during Entamoeba histolytica liver infection

Amoebiasis is the third worldwide disease due to a parasite. The causative agent of this disease, the unicellular eukaryote Entamoeba histolytica, causes dysentery and liver abscesses associated with inflammation and human cell death. During liver invasion, before entering the parenchyma, E. histolytica trophozoites are in contact with liver sinusoidal endothelial cells (LSEC). We present data characterizing human LSEC responses to interaction with E. histolytica and identifying amoebic factors involved in the process of cell death in this cell culture model potentially relevant for early steps of hepatic amoebiasis. E. histolytica interferes with host cell adhesion signalling and leads to diminished adhesion and target cell death. Contact with parasites induces disruption of actin stress fibers and focal adhesion complexes. We conclude that interference with LSEC signalling may result from amoeba-triggered changes in the mechanical forces in the vicinity of cells in contact with parasites, sensed and transmitted by focal adhesion complexes. The study highlights for the first time the potential role in the onset of hepatic amoebiasis of the loss of liver endothelium integrity by disturbance of focal adhesion function and adhesion signalling. Among the amoebic factors required for changed LSEC adherence properties we identified the Gal/GalNAC lectin, cysteine proteases and KERP1.

Protective Effects of N-acetylcysteine and a Prostaglandin E1 Analog, Alprostadil, Against Hepatic Ischemia: Reperfusion Injury in Rats

Ischemia–reperfusion (I/R) injury has a complex pathophysiology resulting from a number of contributing factors. Therefore, it is difficult to achieve effective treatment or protection by individually targeting the mediators or mechanisms. Our aim was to analyze the individual and combined effects of N-acetylcysteine (NAC) and the prostaglandin E1 (PGE1) analog alprostadil on hepatic I/R injury in rats. Thirty male Sprague-Dawley rats were randomly divided into five groups (six rats per group) as follows: Control group, I/R group, I/R + NAC group, I/R + alprostadil group, and I/R + NAC + alprostadil group. The rats received injections of NAC (150 mg/kg) and/or alprostadil (0.05 μg/kg) over a period of 30 min prior to ischemia. These rats were then subjected to 60 min of hepatic ischemia followed by a 60-min reperfusion period. Hepatic superoxide dismutase (SOD), catalase, and glutathione levels were significantly decreased as a result of I/R injury, but they were increased in groups treated with NAC. Hepatic malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) activities were significantly increased after I/R injury, but they were decreased in the groups with NAC treatment. Alprostadil decreased NO production, but had no effect on MDA and MPO. Histological results showed that both NAC and alprostadil were effective in improving liver tissue morphology during I/R injury. Although NAC and alprostadil did not have a synergistic effect, our findings suggest that treatment with either NAC or alprostadil has benefits for ameliorating hepatic I/R injury.

Platelet adhesion and fusion to endothelial cell facilitate the metastasis of tumor cell in hypoxia-reoxygenation condition

To investigate the relevant molecular mechanisms of platelet in promoting metastasis of tumor cell. The adhesion of fluorescence dye labeled-platelet to human liver sinusoidal endothelial cell (LSEC) line and tumor cell lines were detected by fluorescence microscope and fluorescence plate reader or laser scanning confocal microscope. The relevant adhesion molecules were analyzed by the antibody blockage experiment. The immune colloidal gold transmission electron microscope (TEM), flow cytometry and dye transfer were used to decipher the adhesion and fusion of platelet and LSEC. The tumor cells adhesion to vessels in ischemia condition was analyzed on mouse mesenteric vessels and the metastasis and neovascularization of metastatic foci in pulmonary tissue were also detected after tumor cells injected into nude mice via tail veil. After hypoxia-reoxygenation, tumor cell or LSEC markedly increased its adhesion with platelet, which could be blocked by different antibodies to platelet adhesion molecules. Platelet increased adhesion of tumor cell to LSEC in dose-dependent manner. The fusion of platelet and LSEC was demonstrated by translocation of fluorescent dye from platelet into the adherent LSEC; gpIIb emerged on the LSEC; and confirmed by TEM. The morphological examination found platelet presented between tumor cell and LSEC. Animal experiment indicated that the tumor adhesion to vessels was seldom in normal condition, but increased in ischemia-reperfusion condition, and further significantly enhanced by platelets. The number of tumor metastatic foci and the density of blood vessels within metastatic foci in lung were markedly increased by tumor cell pre-adhered with platelet. The adhesion or fusion of platelet to endothelial cell mediated by platelet surface adhesion molecules, which could promote the adhesion of tumor cell with endothelial cells and the tumor metastasis.

Protective effects of prostaglandin E1 on human umbilical vein endothelial cell injury induced by hydrogen peroxide

AIM

To investigate the protective effects of prostaglandin E(1) (PGE(1)) against H(2)O(2)-induced oxidative damage on human umbilical vein endothelial cells (HUVECs).

METHODS

HUVECs were pretreated with PGE(1) (0.25, 0.50, and 1.00 micromol/L) for 24 h and exposed to H(2)O(2) (200 micromol/L) for 12 h, and cell viability was measured by the MTT assay. LDH, NO, SOD, GSH-Px, MDA, ROS, and apoptotic percentage were determined. eNOS expression was measured by Western blotting and real-time PCR.

RESULTS

PGE(1) (0.25-1.00 micromol/L) was able to markedly restore the viability of HUVECs under oxidative stress, and scavenged intracellular reactive oxygen species induced by H(2)O(2). PGE(1) also suppressed the production of lipid peroxides, such as MDA, restored the activities of endogenous antioxidants including SOD and GSH-Px, and inhibited cell apoptosis. In addition, PGE(1) significantly increased NO content, eNOS protein, and mRNA expression.

CONCLUSION

PGE(1) effectively protected endothelial cells against oxidative stress induced by H(2)O(2), an activity that might depend on the up-regulation of NO expression.

Prostaglandin E1 prevents liver failure after excessive hepatectomy in the rat by up-regulating Cyclin C, Cyclin D1, and Bclxl

Prostaglandin E1 (PGE1) has wide-ranging effects on cytoprotection and may play a role in preventing liver failure following excessive hepatectomy. We examined the effect of PGE1 on hepatocyte apoptosis and liver regeneration after 95% hepatectomy in a rat model. PGE1 or vehicle was intravenously administered 30 minutes before and during hepatectomy. The extent of hepatocyte injury was evaluated by serum alanine aminotransferase and aspartate aminotransferase levels. To evaluate hepatocyte apoptosis and liver regeneration, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and Ki67 labeling were performed. The expression levels of Bcl-xL, Bcl-2, Bax, Cyclin C, Cyclin D1, Cyclin E, p21, transforming growth factor-beta, plasminogen activator inhibitor-1, and glyceraldehyde-2-phosphate dehydrogenase mRNA were also examined by reverse transcription-polymerase chain reaction. Survival was improved in the PGE1 group (26.6%), whereas all rats in the vehicle group died within 60 hours. PGE1 significantly suppressed the release of alanine aminotransferase and aspartate aminotransferase at 12 hours postoperatively. Pretreatment with PGE1 significantly increased the Ki67-positive cell count and decreased the terminal deoxynucleotidyl transferase dUTP nick end labeling positive cell count after hepatectomy, and also significantly increased the expression levels of Bcl-xL, Cyclin C, and Cyclin D1. Our results suggest that pretreatment with PGE1 may increase survival following hepatectomy by salvaging the remaining liver tissue, which it does by inhibiting apoptosis and stimulating hepatocyte proliferation.

Hepatoprotective effects of misoprostol and silymarin on carbon tetrachloride-induced hepatic damage in rats

The aim of this study was to investigate the effect of misoprostol, silymarin or the co-administration of misoprostol + silymarin on the carbon tetrachloride (CCl(4))-induced hepatic injury in rats. Misoprostol (10, 100, 1000 microg/kg), silymarin (25 mg/kg) or misoprostol (100 microg/kg) + silymarin (25 mg/kg) was given once daily orally simultaneously with CCl(4) and for 15 days thereafter. The results showed that misoprostol (10, 100 or 1000 microg/kg) conferred significant protection against the hepatotoxic actions of CCl(4) in rats, reducing serum alanine aminotransferase (ALT) levels by 24.7%, 42.6% and 49.4%, respectively compared with controls. Misoprostol, given at 100 or 1000 microg/kg, decreased aspartate aminotransferase (AST) by 28 and 43.6% and alkaline phosphatase (ALP) by 19.3% and 53.4% respectively. Meanwhile, silymarin reduced ALT, AST and ALP levels by 62.7%, 66.1% and 65.1% respectively. The co-administration of misoprostol (100 microg/kg) and silymarin (25 mg/kg) resulted in 61.4%, 66.1% and 57.5% reduction in ALT, AST and ALP levels respectively. Histopathological alterations and depletion of hepatocyte glycogen and DNA content by CCl(4) were markedly reduced after treatment with misoprostol, silymarin or misoprostol + silymarin. Image analysis of liver specimens revealed a marked reduction in liver necrosis; area of damage: 32.4%, 24% and 10.2% after misoprostol (10, 100 or 1000 microg/kg), 7.2% after silymarin and 10.9% after treatment with misoprostol 100 microg/kg + silymarin, compared with CCl(4) control group (46.7%). These results indicate that treatment with misoprostol protects against hepatocellular necrosis induced by CCl(4). This study suggests a potential therapeutic use for misoprostol in liver injury.

Nuclear localization of active matrix metalloproteinase-2 in cigarette smoke-exposed apoptotic endothelial cells

Cigarette smoke (CS)-induced activation of proteases such as matrix metalloproteinases (MMPs) contributes to lung alveolar destruction due to cell death. The aim of this study was to determine whether MMPs are produced in pulmonary artery endothelial cells (PAECs) and whether CS activation of MMPs is associated with apoptosis. Cultured PAECs were exposed to CS and subjected to assessments of apoptosis and MMPs. Western blotting and in situ zymography were performed to localize gelatinolytic activity and to identify enzymes. CS-induced apoptosis, i.e., enhanced annexin V binding and cleaved poly-ADP-ribose-polymerase (PARP), correlated with increased degradation of gelatin, a substrate of MMPs. The levels of pro-MMP-2 and active MMP-2 were increased in cytosolic and nuclear fractions isolated from CS-exposed cells. MMP-2 protein colocalized with gelatinolytic activity in the nucleus of CS-exposed cells undergoing apoptosis. These observations support the notion that MMP-2 contributes to CS-induced gelatinase activity, which localizes in the nuclear region primarily and correlates with annexin V binding and PARP cleavage. This suggests a novel function of MMP-2 in the degradation of the nuclear matrix in CS-induced endothelial apoptosis.

Antibody library-based tumor endothelial cells surface proteomic functional screen reveals migration-stimulating factor as an anti-angiogenic target

Angiogenesis is critical for cancer development and metastasis. Here we have employed a functional antibody library-based proteomic screen to identify proteins that participate in and might be used as therapeutic targets for tumor-related angiogenesis. Mice were immunized with human esophageal cancer endothelial cells (HECEC). The antibody library was established with the mouse spleen cells the serum of which had most anti-angiogenic effect. Monoclonal antibodies were subjected to an immunoreactive and functional screen and monoclonal antibodies that reacted strongly with cell surface antigens of HECECs and influenced their behavior were selected. Antigens that recognized by the antibodies were obtained by immunoprecipitation and then identified by mass spectrometry analysis. Migration-stimulating factor (MSF), the antigen of 1D2 antibody was identified using this approach. Further studies demonstrated that the 1D2 antibody suppressed MSF-effected migration and adhesion of HECECs on fibronectin matrix. Biodistribution assay showed that MSF targeting antibody 1D2 could specifically home to the xenograft with humanized blood vessel. Targeting treatment with 1D2 antibody significantly suppressed tumor growth through inhibition of human tumor-related angiogenesis. These results indicate that the functional antibody library-based proteomic screen can successfully identify proteins that involved in tumor-related angiogenesis and MSF may be a target for the anti-angiogenic treatment of the esophageal cancer.

Reduced glutathione in the liver as a potential viability marker in non-heart-beating donors

Although the use of non-heart-beating donors (NHBD) is the oldest type of organ transplantation, the results were and still are disappointing. To consider using a liver from NHBD, it is of importance to assess the graft viability. Our aim was to assess the role of reduced liver glutathione (rGSHL) as a potential predictive marker of liver function before transplantation. Autotransplanted livers were subjected to 0, 60, and 90 minutes of ischemia in 20 pigs. We analyzed systemic cardiocirculatory parameters, bowel ischemia by endotoxin, endotoxin-neutralizing capacity, oxidative stress, hepatic perfusion parameters, liver enzymes, local bowel ischemia, and liver oxidative stress (rGSHL and oxidized glutathione in the liver). Autotransplantation was comparable to donor explantation/recipient transplantation with respect to systemic and hepatic parameters. Liver ischemia for 0, 60, and 90 minutes resulted in survival in 100% (NHBD-0), 71% (NHBD-60), and 57% (NHBD-90) of animals. Of all parameters, only hepatic microperfusion, pHi of the sigmoid colon, and bowel ischemia by endotoxin in the NHBD-90 group showed significant changes compared to NHBD-60 and control animals. Although systemic endotoxin-neutralizing capacity and total glutathione in erythrocytes levels were mainly influenced by cold perfusion, hepatic oxidative stress increased with ischemia time. The cut-off value of 11.5 ng/mmol of rGSHL could distinguish survivors from nonsurvivors, independent of the ischemia time. In conclusion, rGSHL has the potential of becoming an important viability marker, as it could predict survival in autotransplantation NHBD model regardless of the ischemia time. Further investigation to declare reasons for differing rGSHL levels within the liver is required.

Enhancement of the action of the antivascular drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA; ASA404) by non-steroidal anti-inflammatory drugs

AIM

5,6-Dimethylxanthenone-4-acetic acid (DMXAA) (ASA404), a low molecular weight antivascular drug currently in clinical trial, acts both directly on the tumour vascular endothelium and indirectly through the induction of inflammatory cytokines and other vasoactive molecules from macrophages and other host cells. We wished to determine whether co-administration of non-steroidal anti-inflammatory drugs (NSAIDs) could modulate the antivascular effects of DMXAA in mice.

METHODS

The effects of diclofenac, salicylate, ibuprofen, celecoxib and rofecoxib on the antitumour response to DMXAA were compared using growth delay assays of Colon 38 adenocarcinomas in C57Bl mice. Concentrations of DMXAA in mice were measured by high performance liquid chromatography.

RESULTS

Administration of DMXAA alone (25 mg/kg i.p.) or of NSAIDs alone induced small tumour growth delays from 2 to 7 days. Co-administration of each of the NSAIDs augmented DMXAA effects with tumour growth delays from 4.5 to >20 days. The possibility of a pharmacokinetic interaction was investigated using diclofenac and it was found that diclofenac did not affect DMXAA pharmacokinetics.

CONCLUSIONS

NSAIDs increase the antitumour activity of DMXAA in a murine tumour model. The effects are consistent with hypothesis that NSAIDs antagonises some of the protective effects of prostaglandins released in response to vascular injury. Co-administration of NSAIDs with DMXAA might be considered as a possible strategy for use in combination cancer therapy.

Prostaglandin analogue misoprostol attenuates neurotoxin 1-methyl-4-phenylpyridinium-induced mitochondrial damage and cell death in differentiated PC12 cells

Defects in mitochondrial function have been shown to participate in the induction of neuronal cell injury. The present study assessed the preventive effect of a prostaglandin E(1) analogue misoprostol against the toxicity of parkinsonian neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) with respect to the mitochondria-mediated cell death process and oxidative stress. MPP(+) induced the nuclear damage, the changes in the mitochondrial membrane permeability, the formation of reactive oxygen species and the depletion of GSH, which leads to cell death in differentiated PC12 cells. Misoprostol prevented the toxic effect of MPP(+). Treatment with misoprostol significantly attenuated the MPP(+)-induced mitochondrial membrane permeability change that leads to the increase in pro-apoptotic Bax and Cytochrome c levels, and subsequent caspase-3 activation. The protective effect of misoprostol may be supported by the inhibitory effect of prostaglandin E(1) on the MPP(+) toxicity. Misoprostol significantly attenuated another parkinsonian neurotoxin rotenone-induced cell death. The results show that misoprostol may prevent the MPP(+) toxicity by suppressing the mitochondrial membrane permeability change that leads to the Cytochrome c release and caspase-3 activation. The preventive effect seems to be ascribed to the inhibitory effect on the formation of reactive oxygen species and depletion of GSH.

The role of adhesion molecules, alpha v beta 3, alpha v beta 5 and their ligands in the tumor cell and endothelial cell adhesion

Tumor metastasis is a complex process involving the interaction between tumor cells and endothelial cells in which some adhesion molecules play an important role. It was our aim to investigate the role of the adhesion molecules, alpha v beta 3 and alpha v beta 5 and their ligands, developmental endothelial locus-1 (Del-1) and L1, in tumor cell adhesion to endothelial cells in vitro. In this study, the expression and regulation of alpha v beta 3, alpha v beta 5 and intercellular adhesion molecule -1 on liver sinusoidal endothelial cells and liver cancer endothelial cells (T3A) were analyzed by real-time PCR and fluorescent-activated cell sorter. The expression and regulation of the integrin ligands, Del-1 and L1, in six tumor cell lines were analyzed by real-time PCR and western blot. We found the expressions of alpha v beta 3 and alpha v beta 5 were higher on T3A than that on liver sinusoidal endothelial cells, whereas expression of intercellular adhesion molecule-1 was lower on T3A than that on liver sinusoidal endothelial cells. After 24 h hypoxia, the expressions of alpha v beta 3 and alpha v beta 5 were upregulated on T3A and liver sinusoidal endothelial cells; the expression of intercellular adhesion molecule-1 was increased on liver sinusoidal endothelial cells, but remained unchanged on T3A. Del-1 and L1 expression levels were obviously diverse in various tumor cell lines and differentially modulated after 12 h hypoxia. The adhesion of tumor cells with Del-1 and L1 expression was higher in T3A than that in liver sinusoidal endothelial cells, and was significantly increased under hypoxic conditions. Interestingly, the tumor cell adherence could be inhibited by antibodies against alpha v beta 5 and alpha v beta 5, but not by an antibody against intercellular adhesion molecule-1. The adhesion of tumor cells without Del-1 and L1 expression was also higher on T3A than that on liver sinusoidal endothelial cells, but the adhesion could not be inhibited by antibodies against alpha v beta 5, alpha v beta 5 or intercellular adhesion molecule-1, suggesting that other receptors are involved. In conclusion, alpha v beta 5, alpha v beta 5 and their ligands Del-1 and L1 play an important role in the process of tumor cells moving from the original place.

Omega 3 - Omega 6: What is right for the liver?

Linoleic and alpha-linolenic acids are the fatty acids designated as "essential" since they are not synthesized by mammalian cells and must be provided in the diet. The recent dietary shift towards the consumption of n-6 (omega-6) at the expense of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) is thought to be a primary cause of many diseases related to the Western diet. The body converts linoleic acid to arachidonic acid and derives eicosapentaenoic acid from alpha-linolenic acid. Ideally the effects of these fatty acids and their eicosanoid derivatives are tailored to the specific biological needs of the body. The balance between n-3 and n-6 PUFAs is essential for metabolism and maintenance of the functions of both classes. The availability of n-3 long chain PUFAs plays a major role in regulating both fat accumulation and its elimination by the liver. Derangement of hepatic n-6:n-3 PUFA ratio impacts on the histological pattern of fatty liver through modulation of the amount of intrahepatic lipids. Moreover, the influence of PUFAs and their eicosanoid products on hepatic microcirculation and ischemia/reperfusion injury has been demonstrated in many studies. This concise review article will focus on the role of PUFAs and eicosanoids in hepatic steatosis, microcirculation and ischemia/reperfusion injury.

Phenotypic and Functional Differences between Human Liver Cancer Endothelial Cells and Liver Sinusoidal Endothelial Cells

BACKGROUND/AIMS

The phenotypic and functional characteristics of microvascular endothelial cells derived from human liver cancer (HLCEC) were analyzed in vitro and compared with those of human liver sinusoidal endothelial cells (LSEC).

METHODS AND RESULTS

Flow-cytometric and real-time PCR analysis indicated that expressions of tumor necrosis factor receptor (TNFR) p75, alphavbeta3 and alphavbeta5 were increased, while those of TNFR p55 and intercellular-adhesion molecule 1 (ICAM-1) were decreased in HLCEC compared with LSEC. The functional analysis indicated that HLCEC exhibited higher angiogenic ability than LSEC, including proliferation capacity, ability to form capillary-like networks and release of matrix metalloproteinases. In response to tumor necrosis factor, LSEC exhibited a significant dose-dependent cytotoxicity, while HLCEC did not. Moreover, the coagulant and fibrinolytic capacity was increased in HLCEC. In addition, tumor cell adherence was significantly higher on HLCEC than on LSEC, while leukocyte adherence was lower on HLCEC than on LSEC. The cytoadherence of HLCEC was inhibited by antibodies against alphavbeta3 and alphavbeta5,and of LSEC by antibodies against ICAM-1.

CONCLUSION

These results indicate that tumor-derived endothelial cells are phenotypically and functionally different from those derived from normal liver tissue. These differences are valuable for understanding tumor angiogenesis and metastasis.

A caspase inhibitor, IDN-6556, ameliorates early hepatic injury in an ex vivo rat model of warm and cold ischemia

This study examined the efficacy of the caspase inhibitor, IDN-6556, in a rat model of liver ischemia-reperfusion injury. Livers from male Sprague-Dawley rats were reperfused for 120 minutes after 24 hours of 4 degrees C cold storage in University of Wisconsin solution. Portal blood flow measurements estimated sinusoidal resistance, and bile production, alanine aminotransferase activities, and Suzuki scores were evaluated as parameters of hepatocyte/liver injury. Treated livers were exposed to 25 or 50 microM of IDN-6556 in University of Wisconsin storage solution and/or the perfusate. All treatment regimens with IDN-6556 significantly improved portal blood flow measured at 120 minutes, and significant improvements were seen as early as 30 minutes when inhibitor was also present in the perfusate (P < 0.01). All treatment groups with IDN-6556 significantly increased bile production by 3-4-fold compared with controls (P < 0.01), and reductions in alanine aminotransferase activities were seen within 90 minutes of reperfusion (P < 0.05). These data were confirmed by improved Suzuki scores (less sinusoidal congestion, necrosis, and vacuolization) in all treated groups. Livers from the IDN-6556-treated groups had markedly reduced caspase activities and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling)-positive cells, suggesting reductions in apoptosis. IDN-6556 present in cold storage media ameliorated liver injury due to cold ischemia and reperfusion injury and may be a rational therapeutic approach to reduce the risk of liver ischemia in the clinical setting.

The effect of intraportal prostaglandin E1 on adhesion molecule expression, inflammatory modulator function, and histology in canine hepatic ischemia/reperfusion injury

BACKGROUND

Prostaglandin E1 (PGE1) is known to protect the liver from I/R, however, the mechanism of cytoprotection is not well understood. This study investigates the effect of intraportal infusion of PGE1 in a warm liver ischemia/reperfusion (I/R) model on cytokines, adhesion molecules and liver structure.

MATERIALS AND METHODS

Twenty dogs underwent laparotomy under general anesthesia. PGE1 (0.02 microg\kg\min) was perfused through the portal vein in the PGE1 group (n = 10), or a similar volume of Ringer's solution in the control group (n = 10) for 15 min. Liver ischemia was induced by hepatic artery and portal vein occlusion and PGE1 was infused via the portal vein for 60 min. The occlusion was released and PGE1 infusion recommenced for 30 min. Blood and liver biopsies were sampled at baseline, 60 min ischemia, and 30 min reperfusion and assessed for transaminases, cytokines, adhesion molecules, and electron microscopy.

RESULTS

PGE1 infusion significantly reduced transaminases TNF-alpha, sICAM-1, sP-selectin, and sE-selectin on ischemia and reperfusion. PGE1 reduced hepatocytic degeneration, portal and central ICAM-1 expression, central and sinusoidal VCAM-1 expression, portal and central P-selectin expression, and portal and sinusoidal E-selectin expression on reperfusion.

CONCLUSION

Intraportal PGE1 infusion reduced I/R injury and was associated with down-regulation of ICAM-1, VCAM-1, P-selectin, and E-selectin on reperfusion.

Morphologic, phenotypic and functional characteristics of endothelial cells derived from human hepatic cavernous hemangioma

BACKGROUNDS/AIMS

The pathogenesis of cavernous hemangiomas is largely unknown, and it is speculated that abnormal vasculogenesis and angiogenesis may be involved. In this study, the characteristics of cavernous hemangioma endothelial cells (CHECs) derived from the human liver were analyzed in terms of morphology, phenotype and function and compared with human liver sinusoidal endothelial cells (LSECs).

METHODS AND RESULTS

By transmission electron microscopy, abnormally expanded endoplasmic reticulum (ER) and similarly arranged cytoplasmic vacuoles were only found in CHECs. Phenotypic analysis showed that the expression of alphavbeta3 was significantly increased in CHECs. mRNA expression of vascular endothelial growth factor A, and angiopoietins 1 and 2 was significantly increased in CHECs compared to LSECs. The functional analysis indicated that CHECs released more vascular endothelial growth factor A, produced significantly more pro-matrix metalloproteinase 2 (pro-MMP2) and activated MMP2, and exhibited higher procoagulant and fibrinolytic activities compared with LSECs. Confocal microscopy revealed that MMP2 was concentrated in some cytoplasmic granules of CHECs and was consistent with the distribution of expanded ER. CHECs exhibited more activated angiogenesis capacity and formed abnormal capillary-like structures in vitro.

CONCLUSION

These results suggested that endothelial cells (ECs) derived from human cavernous hemangiomas differ from normal ECs in morphology, phenotype and function.

The Use of Prostaglandins in the Immediate Postsurgical Liver Transplant Period

INTRODUCTION

Experimental evidence has suggested that prostaglandins have positive effects on hepatic perfusion after transplantation. However, randomized clinical trials have failed to show their usefulness to decrease the incidence of primary nonfunction. In order to demonstrate its therapeutic role, we performed a clinical study in which PGE1 was administered only after the appearance of posttransplant liver dysfunction.

MATERIALS AND METHODS

Forty patients with macroscopic signs of hypoperfusion or lacking bile production at the end of the operation (n = 24) or with an increase in transaminases and fall in biliary production in the first 24 hours postsurgery (n = 16) were administered alprostadil (PGE1; 0.01 mug/kg/min to the maximum plateau of 0.06 mug/kg/min). We measured the mean values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), activated thromboplastin time-ratio (aPTT-r), international normalized ratio (INR), bilirubin, creatinine and plasma nitrogen, PaO(2)/FiO(2) at the start of the treatment and every 6 hours for 48 hours, and daily diuresis.

RESULTS

There appeared to be a significant decrease in AST, INR, aPTT-r, and creatinine clearance (P < .05), while there was a significant rise in the blood urea nitrogen (P < .001). ALT and bilirubin did not show significant variations. The PaO(2)/FiO(2) ratio showed a significant decrease (P < .001) in pulmonary vasodilatation.

CONCLUSIONS

Prostaglandins used in the manner in our study showed a significant efficiency to improve liver dysfunction after transplantation.

Hypoxia-reoxygenation-induced apoptosis in cultured neonatal rat cardiomyocyets and the protective effect of prostaglandin E

The aim of the present study was to investigate the effect of prostaglandin (PG) E1 on hypoxia/re-oxygenation (H/R) apoptosis and the expression of bcl-2 and bax in cultured neonatal rat cardiomyocytes. The H/R model was made using the first generation of cultured neonatal rat cardiomyocytes. Hypoxia/re-oxygenation apoptosis was studied by electron microscopy and agarose gel electrophoresis. The percentage of apoptotic cells was measured by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL). The expression of bcl-2 and bax was detected by in situ hybridization and immunohistochemical staining. Most cells of the H/R group tested by electron microscopy showed cytoplasmic concentration, nuclear chromatin condensation and margination. Prostaglandin E1 (5, 15 and 45 microg/L) relieved the injury. The results of DNA electrophoresis in the H/R group showed a typical DNA ladder and the DNA ladder decreased gradually corresponding with increasing doses of PGE1. The TUNEL staining showed that the total number of apoptotic cells in the H/R group was much more than that in the PGE1 (45 microg/L) group. The results of in situ hybridization and immunohistochemical staining showed that the bcl-2 content in the H/R group was lower than that in the control group; bax content showed the reverse. Compared with the H/R group, bcl-2 content was significantly higher in the PGE1 (5, 15 and 45 microg/L) groups. However, bax content in the PGE1 (5, 15 and 45 microg/L) groups was significantly lower than that in the H/R group. 6. In conclusion, H/R injury can induce cardiomyocyte apoptosis. Prostaglandin E1 obviously has anti-apoptotic effects on cardiomyocytes and the mechanisms probably involve the inhibition of bax expression and increased expression of bcl-2.

Oxygen radicals and matrix metalloproteinases mediate reperfusion liver injury

Many pathological processes involve the breakdown and remodeling of the extracellular matrix, which is mediated by the family of important enzymes known as matrix metalloproteinases (MMPs). One such process is warm ischemia/reperfusion (I/R) injury, the most important cause of dysfunction of liver allografts. We monitored protein expression of MMP-9 by Western blotting in rat liver after I/R. We also monitored changes in total MMP activity in the serum before and after I/R. Ischemia was induced by clamping the common hepatic artery and portal vein for 40 minutes and reperfusing for 90 minutes. Blood samples collected before ischemia and after reperfusion were analyzed for AST, hydroxyl radical, and tumor necrosis factor (TNFalpha). This protocol resulted in a high level of MMP-9 expression in liver tissue. Total MMP activity in serum was also significantly increased. Levels of AST, hydroxyl radicals, and TNF alpha were concomitantly increased. Ilomastat, an MMP inhibitor, attenuated the I/R-induced liver injury. After administration of the oxygen radical scavenger N-acetylcysteine (NAC), total MMP activity was suppressed, and liver injury was again attenuated. These results indicated that reperfusion liver injury induced an increase in MMP-9 protein expression and in serum MMP activity. The protective effects of an MMP inhibitor and NAC indicate that oxygen radical production is involved in MMP expression and liver injury associated with I/R.

Assessment of apoptosis in epidermal lamellar cells in clinically normal horses and those with laminitis

OBJECTIVE

To determine and compare the number, type, location, and distribution of apoptotic epidermal cells in the laminae of clinically normal horses and horses with laminitis.

SAMPLE POPULATION

Formalin-fixed samples of digital lamellar tissue from 47 horses (including clinically normal horses [controls; n = 7], horses with acute [4] and chronic [7] naturally acquired laminitis, and horses with black walnut extract-induced [11] or carbohydrate overload-induced [18] laminitis).

PROCEDURE

Blocks of paraffin-embedded lamellar tissues were stained for DNA fragmentation with the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) technique. Differential immunohistochemical staining for caspases 3 and 14 were used to confirm apoptosis.

RESULTS

The number of TUNEL-positive epidermal cells per 0.1 mm of primary laminae was significantly greater in the acute laminitis group than in the other groups. In the acute laminitis group, there were 17 and 1,025 times as many TUNEL-positive basal layer cells and keratinocytes, respectively, compared with the control group. Apoptosis of TUNEL-positive basal layer cells was confirmed by results of caspase 3 immunohistochemical staining. The TUNEL-positive keratinocytes did not stain for caspases 3 or 14.

CONCLUSIONS AND CLINICAL RELEVANCE

The large number of apoptotic basal layer cells detected in the lamellar tissue of horses with acute naturally acquired laminitis suggests that apoptosis may be important in the development of acute laminitis. The role of the large number of TUNEL-positive keratinocytes detected in the interface of primary and secondary epidermal laminae of horses with acute laminitis remains to be elucidated.

Lentiviral Vector: A Useful Tool for Transduction of Human Liver Endothelial Cells

Endothelial cells play multiple roles in pathophysiologic processes and are increasingly being recognized as target cells of gene therapy. Lentiviral vectors derived from human immunodeficiency virus type 1 have an ability to infect both dividing and nondividing cells and currently receive a great deal of attention as an innovative tool for transduction of target cells. The purpose of the present work was to evaluate the efficacy of a lentiviral vector for transducing human liver endothelial cells (HLECs) in vitro. For the present study, a pseudotyped lentiviral vector encoding a green fluorescent protein (GFP) gene, LtV-GFP, was generated by means of FuGENE 6 method and allowed to infect HLECs. Approximately 95% of HLECs were positive for GFP expression after LtV-GFP infection at a multiplicity of infection of 10. Notably, LtV-GFP transduced HLECs had stable and long term GFP expression, showed gene expression of endothelial markers including CD 34, factor VIII, flt-1, KDR/flk-1 and HGF, and maintained in vitro angiogenic potential in a Matrigel assay to the same extent as primarily cultured HLECs. These findings provide evidence that lentivirus based gene delivery is an efficient tool for transduction of endothelial cells that could be considered for cell and gene therapies and hybrid artificial organs.

The caspase inhibitor IDN-6556 prevents caspase activation and apoptosis in sinusoidal endothelial cells during liver preservation injury

Cold ischemia (CI)-warm reperfusion (WR) liver injury remains a problem in liver transplantation. CI-WR initially causes sinusoidal endothelial cell (SEC) apoptosis through a caspase-dependent mechanism. We previously showed that the caspase inhibitor IDN-1965 prevents CI-WR-induced SEC apoptosis. However, this agent required to be administered to the donor, preservation solution, and recipient for efficacy. Here, we show that a second-generation caspase inhibitor, IDN-6556, effectively prevents CI-WR-induced SEC injury when added only to University of Wisconsin (UW) cold storage media. Rat livers were stored in UW solution for 24 hours at 4 degrees C and reperfused for 1 hour at 37 degrees C. Apoptosis was quantitated using terminal deoxynucleotide transferasemediated deoxyuridine triphosphate nick end labeling (TUNEL) assay and caspase 3 activation determined by biochemical measurement and immunohistochemical analysis. Pan-caspase inhibitors (IDN-8066, IDN-7503, IDN-7436, IDN-1965, and IDN-6556) were applied at preischemic, cold preservation, or reperfusion periods. TUNEL-positive SEC and caspase 3-like activity in the liver was increased by CI-WR. Three caspase inhibitors (IDN-8066, IDN-1965, and IDN-6556) effectively attenuated SEC apoptosis and caspase 3 activation. The most potent inhibitor, IDN-6556, reduced SEC apoptosis and caspase 3 activity by 55% and 94%, respectively. Prevention of SEC apoptosis by IDN-6556 was not reduced when this agent was administered only during the cold preservation period. When added to the preservation solution, the caspase inhibitor IDN-6556 appears to be a feasible therapeutic agent against ischemia-reperfusion injury in liver transplantation.