Early expression of hepatocyte growth factor, interleukin-6, and transforming growth factor-beta1 and -beta2 in symptomatic infection in patients who have undergone liver transplantation.

INTRODUCTION: Early septic complications may be a deciding factor for successful recovery among patients who have undergone orthotopic liver transplantation. Therefore, monitoring liver function parameters plays an important role in postoperative treatment to achieve an early diagnosis of postsurgical complications. We ought to measure standard liver function parameters and the expression levels for selected cytokines among patients exhibiting symptoms of infection after orthotopic liver transplantation. MATERIALS AND METHODS: The study was performed on 30 patients who were divided into two groups: SI-0 consisted of patients free of infection, and SI-1, those who had symptoms of infection. We determined standard liver function parameters and expression of hepatocyte growth factor (HGF), interleukin (IL)-6, transforming growth factor (TGF)-beta1, and TGF-beta2. RESULTS: There were no significant differences in standard liver function parameters between the two groups of patients. There were no significant differences in the levels of expression for the cytokines in question between the two groups of patients. CONCLUSIONS: Although standard liver function parameters provide diagnostically valuable information on the patient's condition, they cannot be used to determine the extent of systemic infection among patients showing signs of infection after liver transplantation. Determining gene expression levels in circulating lymphocytes is a sensitive method to monitor patients' condition after liver transplantation. The expression levels of HGF, IL-6, TGF-beta1, and TGF-beta2 in circulating lymphocytes were not sufficiently specific to diagnose transitory postsurgical complications such as symptomatic infection.

Overexpression of CD39/nucleoside triphosphate diphosphohydrolase-1 decreases smooth muscle cell proliferation and prevents neointima formation after angioplasty.

BACKGROUND: Growing evidence implicates the involvement of extracellular nucleotides in the regulation of platelet, leukocyte, endothelial cell (EC) and vascular smooth muscle cell (VSMC) phenotype and function. Within the quiescent vasculature, extracellular nucleotides are rapidly hydrolyzed by CD39, the dominant endothelial nucleoside triphosphate diphosphohydrolase (NTPDase-1). However, vascular CD39/NTPDase-1 activity is lost in EC activated by oxidative stress or proinflammatory mediators, and upon denudation of the endothelium following balloon injury. The consequent increase in extracellular nucleotide concentrations triggers signaling events leading to prothrombotic responses and increased VSMC proliferation. OBJECTIVES: To investigate the effect of overexpressed CD39/NTPDase-1 in injured aorta. METHODS: Using adenoviral-mediated gene transfer we expressed CD39/NTPDase-1 in mechanically denudated rat aortas. We measured intima formation by morphometry and VSMC proliferation by the [(3)H]-thymidine incorporation assay. RESULTS: Targeted expression of CD39 in injured vessels increased NTPDase activity (from 2.91 +/- 0.31 to 22.07 +/- 6.7 nmols Pi mg(-1) protein, 4 days after exposure to the adenovirus) and prevented the formation of neointima. The thickness of the intimal layer in injured aortas exposed to Ad-CD39 was 26.2 +/- 3.9 microm vs. 51.8 +/- 6.1 microm and 64.4 +/- 22.2 microm (P < 0.001) in vessels treated with Ad-beta-gal and saline, respectively. Moreover, targeted expression of CD39/NTPDase-1 caused a 70% (P < 0.01) decrease in proliferation of VSMC isolated from transduced rat aortas as compared with VSMC derived from control vessels. CONCLUSIONS: The presented data suggest that increasing CD39/NTPDase-1 activity in VSMC could represent a novel therapeutic approach for the prevention of stenosis associated with angioplasty and other occlusive vascular diseases.

Clinical significance of lymphocytes hepatocyte growth factor mRNA expression in patients after liver transplantation.

UNLABELLED: Hepatocyte growth factor (HGF) plays a key role in the regulation of liver regeneration after hepatocyte damage. Changes in HGF gene expression reflect the status of the regeneration process. AIM: The aim of this study was to ascertain the clinical significance of the expression of HGF among liver transplant patients. METHODS: Expression of the mRNA of HGF among peripheral blood lymphocytes were measured prior to as well as at 1, 2, 6, and 10 days after liver transplantation in a group of 30 liver recipients. RESULTS: In first 24 hours after reperfusion, the patients with compromised graft function (group 1) showed persistently higher HGF gene expression after reperfusion compared with patients displaying well-functioning grafts (group 0; P = .0189). Between postoperative days 1 and 10, there was a rapid decrease in gene expression among group 0 compared with group 1 (P = .0155). The significant decrease observed in the both groups reached a certain plateau after 48 hours postoperatively. There was no statistical difference in aminotransaminase levels over the days after liver transplantation. The decreased mRNA HGF expression in lymphocytes preceded the decrease in aminotransferase levels. CONCLUSIONS: HGF was more sensitive to predict early graft function than prothrombin time, aspartate aminotransferase, and alanine aminotransferase levels. The determination of HGF expression level in lymphocytes after liver transplantation may yield valuable information for evaluation of early graft function.

The effects of indomethacin on angiogenic factors mRNA expression in renal cortex of healthy rats.

Indomethacin is a nonsteroidal anti-inflammatory drug used frequently to control chronic or temporary pain. In the kidney, indomethacin decreases medullary and cortical perfusion, resulting in hypoxia. Kidney hypoxia has many effects, including changes in gene expression, and is a strong stimulus for angiogenesis. Other angiogenic factors include vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2), transforming growth factor beta 1 (TGFbeta1), and platelet-derived growth factor (PDGF). Our goal was to examine the influence of indomethacin on mRNA expression of these factors and their selected receptors in the renal cortex of healthy rats. Groups of 8 healthy, male, six-week-old Wistar rats received either indomethacin (5 mg/kg/day) or placebo orally for three months. RNA from renal cortex biopsies was analyzed by real-time polymerase chain reaction to quantify the mRNA levels of each cytokine. We observed significantly higher mRNA levels for VEGF (1.73-fold), FGF-2 (5.6-fold) and TGFbeta receptor III (2.93-fold), PDGF receptor alpha (2.93-fold) and receptor beta (2.91-fold) in rats receiving indomethacin compared to rats given placebo (p < 0.05). Amounts of mRNA for TGFbeta1, PDGF, FGF receptors 1 and 2 and TGFbeta receptor I did not differ between analysed groups. Our data indicates that indomethacin may regulate the expression of potent angiogenic factors VEGF and FGF-2.

RAFTK/Pyk2 involvement in platelet activation is mediated by phosphoinositide 3-kinase.

Platelet activation by different agonists initiates a signalling cascade involving the phosphorylation of several protein kinases, which control key regulatory events. Previously, we demonstrated that the related adhesion focal tyrosine kinase (RAFTK, Pyk2) was involved in an early phase of platelet activation, independent of integrin and glycoprotein IIb-IIIa activation. In this study, we demonstrate that RAFTK is co-immunoprecipitated with phosphoinositide 3-kinase (PI3K) upon platelet activation, and that thrombin, ADP and collagen induced the phosphorylation of both PI3K and RAFTK. A low dose of thrombin (0.015 U/ml) induced RAFTK phosphorylation and platelet aggregation in a PI3K activity-dependent manner, whereas a high dose of thrombin (0.1 U/ml) induced these events in a PI3K activity-independent manner. ADP and collagen also induced RAFTK phosphorylation and platelet aggregation in a PI3K activity-dependent manner, similar to that of the low-dose thrombin. Furthermore, protein tyrosine phosphatase activity was associated with RAFTK in response to platelet activation, and was found to be that of protein tyrosine phosphatase-2 (SHP-2). The association of SHP-2 with RAFTK was PI3K-dependent and was increased upon RAFTK phosphorylation. Taken together, our results strongly suggest that the involvement of RAFTK in platelet activation is mediated via the PI3K pathway.

Palmitoylation targets CD39/endothelial ATP diphosphohydrolase to caveolae.

Ectonucleotidases influence purinergic receptor function by the hydrolysis of extracellular nucleotides. CD39 is an integral membrane protein that is a prototype member of the nucleoside 5'-triphosphate diphosphohydrolase family. The native CD39 protein has two intracytoplasmic and two transmembrane domains. There is a large extracellular domain that undergoes extensive glycosylation and can be post-translationally modified by limited proteolysis. We have identified a potential thioester linkage site for S-acylation within the N-terminal region of CD39 and demonstrate that this region undergoes palmitoylation in a constitutive manner. The covalent lipid modification of this region of the protein appears to be important both in plasma membrane association and in targeting CD39 to caveolae. These specialized plasmalemmal domains are enriched in G protein-coupled receptors and appear to integrate cellular activation events. We suggest that palmitoylation could modulate the function of CD39 in regulating cellular signal transduction pathways.

Analysis of CD39/ATP diphosphohydrolase (ATPDase) expression in endothelial cells, platelets and leukocytes.

Purinergic signaling may influence hemostasis, inflammatory responses and apoptosis. Therefore, hydrolysis of extracellular ATP and ADP by the ATP diphosphohydrolase (ATPDase) could regulate these processes. We have previously demonstrated the identity between the vascular ATPDase and CD39. Here we show that levels of CD39 expression correlate with ATPDase activity in human endothelial cells (EC), platelets and selected monocyte, NK, and megakaryocyte cell lines. Western blotting revealed one to three isoforms of CD39/ATPDase: mobility variations of major protein resulted from post-translational modifications. Northern blotting and primer extension indicated two major mRNA transcripts and one transcription start point, respectively. In addition, mRNAs specific for purinergic P2 receptors were detected in all of the investigated cells, suggesting that the coexpressed CD39/ATPDase may regulate purinergic signaling. Thrombotic and inflammatory responses may be modulated by the expression of CD39/ATPDase.

Suppression of ATP diphosphohydrolase/CD39 in human vascular endothelial cells.

Vascular ATP diphosphohydrolase/CD39 is an endothelial cell membrane protein with both ecto-ATPase and ecto-ADPase activities. Suppression of constitutive CD39 expression may result in elevated concentrations of ATP and ADP at the vascular interface that could predispose to thrombosis and inflammation. To study the effects of suppression of CD39 synthesis, stable 25-base antisense chimeric oligonucleotides targeting sequences at the 5' region of CD39 were designed. Transfection of these stable oligomers into cultured human endothelial cells resulted in dramatic decreases in levels of CD39 mRNA transcripts. Following transfection with antisense oligonucleotides, total ADPase activity fell from 26.0 +/- 3.1 in control cultures to 9.5 +/- 3.4 nmol of P(i) min(-1) (mg of protein)(-1) (p < 0.005); suppression of CD39 protein expression was also observed by Western blotting. Decreases in ATP diphosphohydrolase activity were associated with increases in concentrations of extracellular purine nucleotides released following stimulation of endothelial cells. Rates of initial hydrolysis of extracellular ATP released from purinergic agonist-stimulated endothelial cells decreased from 17.9 +/- 5.0 to 4.8 +/- 0.5 pmol min(-1) per 10(6) cells (p < 0.005) in antisense transfected cells. Therefore, CD39 regulates extracellular ATP concentrations and may be an important modulator of purinergic receptor activity in vascular endothelial cells.

Delayed sperm incorporation into parthenogenetic mouse eggs: sperm nucleus transformation and development of resulting embryos.

In this study we examined the effect of experimentally induced asynchrony between male and female pronuclei on male pronucleus formation and developmental potential of the resulting mouse embryos. We demonstrate that when the interval between oocyte activation and sperm incorporation is up to 1.5-2 hr, the spermatozoa transform into normal pronuclei. These male pronuclei can replicate their chromosomes during the first embryonic cell cycle and are transcriptionally competent. During the first cleavage these "delayed" male pronuclei condense into discrete mitotic chromosomes and when resulting embryos are transplanted into oviducts of pregnant females at least some of them can develop to term. In contrast, when sperm nuclei are introduced into parthenogenetic eggs 3 hr or more after activation, their transformation into pronuclei is significantly impaired, and they neither replicate nor transcribe. During the first mitosis they form a group of condensed chromatin, which is displaced into one of the resulting blastomeres leading to formation of haploid/diploid mosaic embryos. These mosaic embryos have poor developmental potential: only a few can reach blastocyst stage in vitro and no full-term development of such embryos was observed after transfer into pregnant females. We conclude that the cytoplasmic factors that make possible the transformation of a sperm nucleus into a functional male pronucleus exhaust within 1.5-2 hr after fertilization and that the male genome which had skipped the first cell cycle cannot become a functional partner in the embryonic genome.

Structural elements and limited proteolysis of CD39 influence ATP diphosphohydrolase activity.

CD39, the mammalian ATP diphosphohydrolase (ATPDase), is thought to contain two transmembrane domains and five "apyrase conserved regions" (ACR) within a large extracellular region. To study the structure of this ectoenzyme, human CD39 was modified by directed mutations within these ACRs or by sequential deletions at both termini. ATPDase activity was well preserved with FLAG tagging, followed by the removal of either of the demonstrated C- or N-transmembrane regions. However, deletions within ACR-1 (aa 54-61) or -4 (aa 212-220), as well as truncation mutants that included ACR-1, -4, or -5 (aa 447-454), resulted in substantive loss of biochemical activity. Intact ACR-1, -4, and -5 within CD39 are therefore required for maintenance of biochemical activity. Native and mutant forms of CD39 lacking TMR were observed to undergo multimerization, associated with the formation of intermolecular disulfide bonds. Limited tryptic cleavage of intact CD39 resulted in two noncovalently membrane-associated fragments (56 and 27 kDa) that substantially augmented ATPDase activity. Glycosylation variation accounted for minor heterogeneity in native and mutant forms of CD39 but did not influence ATPDase function. Enzymatic activity of ATPDase may be influenced by certain posttranslational modifications that are relevant to vascular inflammation.

Adenovirus-mediated expression of a dominant negative mutant of p65/RelA inhibits proinflammatory gene expression in endothelial cells without sensitizing to apoptosis.

We hypothesized that blocking the induction of proinflammatory genes associated with endothelial cell (EC) activation, by inhibiting the transcription factor nuclear factor kappaB (NF-kappaB), would prolong survival of vascularized xenografts. Our previous studies have shown that inhibition of NF-kappaB by adenovirus-mediated overexpression of I kappaB alpha suppresses the induction of proinflammatory genes in EC. However, I kappaB alpha sensitizes EC to TNF-alpha-mediated apoptosis, presumably by suppressing the induction of the NF-kappaB-dependent anti-apoptotic genes A20, A1, manganese superoxide dismutase (MnSOD), and cellular inhibitor of apoptosis 2. We report here that adenovirus mediated expression of a dominant negative C-terminal truncation mutant of p65/RelA (p65RHD) inhibits the induction of proinflammatory genes, such as E-selectin, ICAM-1, VCAM-1, IL-8, and inducible nitric oxide synthase, in EC as efficiently as does I kappaB alpha. However, contrary to I kappaB alpha, p65RHD does not sensitize EC to TNF-alpha-mediated apoptosis although both inhibitors suppressed the induction of the anti-apoptotic genes A20, A1, and MnSOD equally well. We present evidence that this difference in sensitization of EC to apoptosis is due to the ability of p65RHD, but not I kappaB alpha, to inhibit the constitutive expression of c-myc, a gene involved in the regulation of TNF-alpha-mediated apoptosis. These data demonstrate that it is possible to block the expression of proinflammatory genes during EC activation by targeting NF-kappaB, without sensitizing EC to apoptosis and establishes the role of c-myc in controlling induction of apoptosis during EC activation. Finally, these data provide the basis for a potential approach to suppress EC activation in vivo in transgenic pigs to be used as donors for xenotransplantation.

Extracellular ATP and ADP activate transcription factor NF-kappa B and induce endothelial cell apoptosis.

Inflammation within the vasculature is associated with endothelial cell (EC) perturbation, loss of vascular ATP-diphosphohydrolase activity, and platelet microthrombus formation with release of ATP and ADP into the micro-environment. The nature and effects of purinergic stimulation of EC under these circumstances remain largely undetermined. ATP and ADP activated EC transcribed mRNA from certain transcription factor NF-kappa B target genes and expressed E-selectin protein on cell membranes. Band shift analysis and reporter assays confirmed the activation of NF-kappa B in response to both ATP and ADP. Apoptosis was shown to occur in response to purinergic signaling, potentially through the activation of P2z/P2x7 receptors. Induction of EC activation responses and apoptosis in response to stimulation with ATP and ADP is associated with activation of NF-kappa B.

Loss of ATP diphosphohydrolase activity with endothelial cell activation.

Quiescent endothelial cells (EC) regulate blood flow and prevent intravascular thrombosis. This latter effect is mediated in a number of ways, including expression by EC of thrombomodulin and heparan sulfate, both of which are lost from the EC surface as part of the activation response to proinflammatory cytokines. Loss of these anticoagulant molecules potentiates the procoagulant properties of the injured vasculature. An additional thromboregulatory factor, ATP diphosphohydrolase (ATPDase; designated as EC 3.6.1.5) is also expressed by quiescent EC, and has the capacity to degrade the extracellular inflammatory mediators ATP and ADP to AMP, thereby inhibiting platelet activation and modulating vascular thrombosis. We describe here that the antithrombotic effects of the ATPDase, like heparan sulfate and thrombomodulin, are lost after EC activation, both in vitro and in vivo. Because platelet activation and aggregation are important components of the hemostatic changes that accompany inflammatory diseases, we suggest that the loss of vascular ATPDase may be crucial for the progression of vascular injury.

Identification and characterization of CD39/vascular ATP diphosphohydrolase.

Vascular ATP diphosphohydrolase (ATPDase) is a plasma membrane-bound enzyme that hydrolyses extracellular ATP and ADP to AMP. Analysis of amino acid sequences available from various mammalian and avian ATPDases revealed their close homology with CD39, a putative B-cell activation marker. We, therefore, isolated CD39 cDNA from human endothelial cells and expressed this in COS-7 cells. CD39 was found to have both immunological identity to, and functional characteristics of, the vascular ATPDase. We also demonstrated that ATPDase could inhibit platelet aggregation in response to ADP, collagen, and thrombin, and that this activity in transfected COS-7 cells was lost following exposure to oxidative stress. ATPDase mRNA was present in human placenta, lung, skeletal muscle, kidney, and heart and was not detected in brain. Multiple RNA bands were detected with the CD39 cDNA probe that most probably represent different splicing products. Finally, we identified an unique conserved motif, DLGGASTQ, that could be crucial for nucleotide binding, activity, and/or structure of ATPDase. Because ATPDase activity is lost with endothelial cell activation, overexpression of the functional enzyme, or a truncated mutant thereof, may prevent platelet activation associated with vascular inflammation.

Erythropoietin production after kidney transplantation.

We studied production of erythropoietin (EPO) in long-term renal allograft recipients with posttransplant erythrocytosis (PTE). Among 951 recipients we found 74 patients with persistent elevation of hematocrit (Htc) value (female > 50%, male > 55%). However, only 63.5% of them had increased red-cell mass ( = "true" erythrocytosis). In all recipients with PTE known causes of secondary erythrocytosis were not found. EPO titer in peripheral blood was significantly higher in recipients with PTE (median 13.5 mIU/mL, range: 0.1-71.5 mIU/mL) as compared to healthy blood donors (median 5.75 mIU/mL, range: 0.1-19.5 mIU/mL) but not different from the group of renal allograft recipients without PTE (median 13.0, range 0.1-71.7 mIU/mL). However, EPO level measured in pretransplant sera was significantly higher in patients who developed PTE (median 16.4 mIU/mL, range: 1.0-281.2 mIU/mL) than in recipients without PTE (median 8.3, range: 1.0-50.3 mIU/mL). A significant difference in EPO level between systemic and effluent blood from native kidneys was found in 6 out of 14 recipients with PTE who underwent catheterization. After phlebotomy patients with PTE responded with higher increase in peak EPO titer than healthy blood donors (527 +/- 473% versus 194.5 +/- 44.2%, p < 0.05). Our results suggest that PTE develops spontaneously due to increased EPO production. Despite elevated EPO levels, regulation of EPO release remains preserved.

Correction of posttransplant erythrocytosis with enalapril.

Erythrocytosis (i.e., elevation in red cell mass) frequently develops after renal transplantation and is associated with increased risk of thromboembolic incidents and hypertension. Because it has been reported that enalapril may induce anemia in renal allograft recipients, we have undertaken a prospective study to estimate the efficacy and safety of enalapril therapy for erythrocytosis and to establish the mechanism by which enalapril reduces red cell mass. Seventeen (12 male and 5 female) long-term renal allograft recipients with increased hematocrit value (> 55% for male and > 50% for female) and elevated red cell mass as determined with 51Cr-labeled autologous erythrocytes were treated with enalapril. After 3 months of therapy, enalapril was withdrawn and patients were observed in order to differentiate spontaneous remission of erythrocytosis from effects of enalapril therapy. After 3 months of the treatment, mean hematocrit decreased from 51.1% (range 47-56%) to 42.9% (range 37-51%; P < 0.01). Red cell mass significantly decreased during this period (from 46.7 ml/kg, range 32.5-60.7 ml/kg, to 32.9 ml/kg, range 20.1-60.1 ml/kg; P < 0.01). Serum erythropoietin levels also changed from 12.2 mIU/ml (range 1.0-33.0 mIU/ml) at baseline to 5.4 mIU/ml (range 0.7-24.2 mIU/ml; P < 0.05). During the following 3 months without enalapril treatment, an increase in hematocrit was noted, reaching 51.7% (range 46-58%; P < 0.05). No serious side effects of enalapril were observed during the study, but there was a need to reduce other hypotensive drugs in some patients. Serum creatinine did not change significantly during enalapril therapy (1.49 mg/dl, range 0.9-2.3 mg/dl, and 1.55 mg/dl, range 1.0-2.3 mg/dl; before and after 3 months of therapy, respectively). Our study proves that enalapril can be safely and effectively used to treat posttransplant erythrocytosis. The effect of enalapril on red cell mass results from reducing erythropoietin production.

Protein kinase C modulators influence meiosis kinetics but not fertilizability of mouse oocytes.

The role of protein kinase C (PKC) in the successive steps of mouse oocyte meiotic process was investigated. We have used either OAG, an analog of diacylglycerol, or mezerein, a nonphorbol ester diterpene, less tumor promoting than phorbol esters, as PKC activators, and staurosporine as PKC inhibitor. Cumulus-free oocytes were cultured in minimum essential medium with each of these PKC modulators and maturation stages were screened every two hours until the end of the process. Both PKC activators prevented GVBD at each tested dose for 4 hr (OAG) and 8 hr (mezerein), and decreased the frequencies of PB oocytes. The inhibitory effects of both activators were dose dependent and reversible. The addition of OAG to the culture medium after GVBD occurrence (i.e., after 4 hrs) did not affect PB extrusion whereas similar addition of mezerein significantly decreased the frequency of PB oocytes. Inhibition of PKC by staurosporine accelerated GVBD and increased the frequency of PB extrusion. When staurosporine was added after GVBD, PB extrusion occurred earlier but PB oocyte frequency was not increased. Fertilizability was not affected when oocyte maturation occurred in the presence of any of these substances despite the delay in maturation process. These results clearly indicate that the PKC pathway is involved in mouse oocyte meiotic process: activation of the enzyme would arrest meiotic process whereas its inhibition would participate in meiosis induction.