Influence of the polymer amount on bioactivity and biocompatibility of SiO2/PEG hybrid materials synthesized by sol-gel technique

SiO2/PEG organic-inorganic hybrid materials, which differ in polyethylene glycol (PEG) content, were synthesized by sol-gel technique and the characterization of their structure and biological properties was carried out in order to evaluate the possible use in biomedical field. FT-IR spectroscopy detected that the two components of the hybrids (SiO2 and PEG) are linked by hydrogen bonds between the Si-OH groups of the inorganic phase and the terminal alcoholic groups and/or the ethereal oxygen atoms in the repeating units of polymer. X-ray diffraction analysis ascertained the amorphous nature of the gels and the observation of their morphology by SEM microscopy confirmed that the interpenetration of the two phases (organic and inorganic) occurs on nanometric scale. The biological characterization was carried out as a function of the polymer amount to study its influence on material behavior. The results showed that the synthesized materials were bioactive and biocompatible. The formation of a hydroxyapatite layer, indeed, was observed on their surface by SEM/EDX analysis after soaking in simulated body fluid. Moreover, the biocompatibility of SiO2/PEG hybrids was assessed performing MTT and SRB cytotoxicity tests on fibroblast cell NIH 3T3 after 24 and 48h of exposure, as well as Trypan Blue dye exclusion test. The response to the presence of the investigated materials was positive. The cell growth and proliferation showed dependence on polymer amount and time of exposure to the material extracts. Therefore, the obtained results are encouraging for the use of the obtained hybrids in dental or orthopedic applications.

Tachykinin receptor modulation of cyclooxygenase-2 expression in human polymorphonuclear leucocytes

BACKGROUND AND PURPOSE

We investigated the ability of natural and synthetic selective NK receptors agonists and antagonists to modulate cyclooxygenase-2 (COX-2) expression in human polymorphonuclear leucocytes (PMNs).

EXPERIMENTAL APPROACH

The presence of all three tachykinin in PMNs was assessed by Western blot and PCR techniques. Natural and synthetic ligands selective for the tachykinin receptors were used to modulate COX-2 protein (measured with Western blotting) and activity [as prostaglandin E(2) (PGE(2)) output]. Effects of substance P (SP) on phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-kappaB) activation were studied to analyse the signalling pathway involved in COX-2 up-regulation mediated by SP.

KEY RESULTS

Stimulation of NK receptors with the natural ligands SP, neurokinin A (NKA) and neurokinin B, in the pmol.L(-1)-micromol.L(-1) concentration range, modulated COX-2 expression and PGE(2) release in a concentration- and time-dependent manner. Experiments with synthetic selective agonists [Sar(9), Met(O(2))(11)]SP, [beta-Ala(8)] NKA(4-10), senktide or selective antagonists L703,606, SR48,968 or SR142801, confirmed that COX-2 up-regulation was mediated by NK receptors. We found that mainly p38, p42 and p46 MAPKs were phosphorylated by SP and SB202190, PD98059 and SP600125, which are selective inhibitors of these kinases, blocked SP-induced COX-2 expression. SP also induced nuclear translocation of NF-kappaB concentration-dependently, with a maximum effect at 1 nmol.L(-1).

CONCLUSIONS AND IMPLICATIONS

Human PMNs possess functional NK(1), NK(2) and NK(3) receptors, which mediate the induction of COX-2 expression and NF-kappaB activation by SP.

Celecoxib decreases expression of the adhesion molecules ICAM-1 and VCAM-1 in a colon cancer cell line (HT29)

BACKGROUND AND PURPOSE

We investigated the ability of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, to modulate expression of ICAM-1 and VCAM-1 in the colon cancer cell line HT29.

EXPERIMENTAL APPROACH

We analysed the effect of celecoxib on ICAM-1 and VCAM-1 protein and mRNA expression in HT29 cells. Experiments were performed in the presence of mitogen-activated protein kinases (MAPK) inhibitors to evaluate the involvement of these kinases in this phenomenon. We evaluated adhesion of HT29 cells to FCS-coated plastic wells in the presence of celecoxib or MAPK inhibitors. Furthermore, we studied the effect of celecoxib on apoptosis.

KEY RESULTS

Celecoxib down-regulated ICAM-1 and VCAM-1 expression in HT29 cells in a time- and dose-dependent way. Celecoxib reduced activation of p38 and p55 c-Jun terminal NH(2) kinase (JNK) MAPKs, but did not affect p46 JNK or p42/44 MAPK phosphorylation. Pretreatment with SB202190 or SP600125, specific inhibitors of p38 and JNK MAPKs, respectively, reduced ICAM-1 and VCAM-1 expression in HT29 cells dose-dependently. Adhesion of HT29 cells to FCS-coated plastic wells was inhibited dose-dependently by celecoxib, and also by SB202190 and SP600125. Celecoxib showed a pro-apoptotic effect, inducing Bax and BID but down-regulating Bcl-2.

CONCLUSIONS AND IMPLICATIONS

Our findings show that celecoxib caused down-regulation of ICAM-1 and VCAM-1, affecting the adhesive properties of HT29 cells in a COX-2 independent way, inhibiting p38 and p55 MAPKs and activating a pro-apoptotic pathway.

Molecular characterization of HHV-8 positive primary effusion lymphoma reveals pathogenetic and histogenetic features of the disease

BACKGROUND

Primary effusion lymphoma (PEL) associates with HHV-8 infection, preferentially develops in immunodeficient patients and grows in the serous body cavities. PEL derives from post-germinal center, pre-terminally differentiated B-cells. The pathogenesis of PEL is unclear and the sole identified genetic lesions are human herpesvirus type-8 (HHV-8) infection in all cases and EBV infection in 70% of cases. Epstein-Barr virus (EBV) infection in PEL displays a latency I phenotype.

OBJECTIVES

To clarify the pathogenesis and histogenesis of PEL by investigating (1) the lymphoma karyotype; (2) the expression status of the Met tyrosine kinase receptor and of its ligand hepatocyte growth factor (HGF); (3) the molecular profile of EBV, with particular focus on mutations of EBNA-1 genes, which are thought to affect viral tumorigenicity in EBV-infected neoplasms displaying the latency I phenotype.

STUDY DESIGN

Twenty-four PEL (nine cell lines and 15 primary specimens) formed the basis of the study. Karyotypes were investigated by conventional cytogenetics and fluorescent in situ hybridization (FISH) in selected cases. The expression status of Met and HGF was defined by multiple techniques, including RT-PCR, FACS analysis, immunocytochemistry, Western blot studies and ELISA. The molecular profile of EBNA-1 genes of EBV were investigated by DNA direct sequencing.

RESULTS

Trisomy 7, trisomy 12 and breaks at 1q21-q25 are recurrently associated with PEL. PEL consistently co-express Met and HGF both at the mRNA and protein level. Among aggressive B-cell lymphomas, Met/HGF co-expression appears to be relatively specific for PEL. The EBNA-1 gene of EBV displays a high degree of genetic heterogeneity in PEL, with no preferential association with one specific variant.

CONCLUSIONS

PEL associates with recurrent chromosomal alterations, suggesting that viral infection is not sufficient for tumor development and that lesions of cellular genes may be required. The expression of Met/HGF by PEL cells may bear implications for the lymphoma proliferation and growth pattern, since Met/HGF interactions influence cell mitogenesis and motogenesis. EBV infection in PEL displays a latency I phenotype and fails to associate with specific EBNA-1 variants, suggesting that the role of EBV in PEL is not mediated by the major transforming pathways currently known in EBV positive lymphomas.

Mutation of BAX occurs infrequently in acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas

Acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (AIDS-NHLs) consistently derive from B cells, are histologically heterogeneous, and are associated with distinct molecular pathways depending upon histology. Recently, it has been proposed that inactivating mutations of the bax death agonist may contribute to the pathogenesis of human tumors. In particular, among B-cell malignancies, BAX mutations have been detected at a certain frequency in Burkitt lymphomas. This study is aimed at defining the status of the BAX gene throughout the clinicopathologic spectrum of AIDS-NHL (n = 54), including AIDS-related Burkitt lymphoma (n = 14), AIDS-related Burkitt-like lymphoma (n = 8), AIDS-related diffuse large cell lymphoma (n = 15), AIDS-related primary central nervous system lymphoma (n = 6), and AIDS-related primary effusion lymphoma (n = 11). All 6 BAX exons and flanking sequences were subjected to mutational analysis by polymerase chain reaction-single strand conformation polymorphism followed by DNA direct sequencing of positive cases. Mutations of BAX among AIDS-NHL were restricted to a cell line of AIDS-related primary effusion lymphoma, which harbored a frameshift mutation causing the introduction of a proximal stop codon. All other AIDS-NHL displayed wild-type BAX alleles. In order to investigate whether BAX inactivation in AIDS-NHL may occur through mechanisms other than gene mutation, bax protein expression was investigated by Western blot analysis or immunohistochemistry in selected cases. All AIDS-NHL analyzed expressed normal bax proteins. Overall, this study indicates that deregulation of apoptotic control in AIDS-NHL is not caused by BAX alterations. Genes Chromosomes Cancer 27:177-182, 2000.

The tyrosine kinase receptor met and its ligand HGF are co-expressed and functionally active in HHV-8 positive primary effusion lymphoma

Primary effusion lymphoma (PEL) harbors consistent infection by human herpesvirus-8, preferentially develops in immunodeficient patients and selectively localizes to the serous body cavities. Histogenetic analysis has suggested that PEL originates from post-germinal center, pre-terminally differentiated B cells sharing phenotypic features with plasma cells. Here we have investigated the expression status and functional integrity of the Met tyrosine kinase receptor and of its ligand hepatocyte growth factor (HGF). Thirteen PEL (nine cell lines and four primary specimens) were analyzed for Met and HGF expression and function by multiple assays. For comparison, a panel of 34 high grade B cell non-Hodgkin lymphomas (NHL) other than PEL was also investigated. Co-expression of Met and HGF was found in all PEL analyzed, whereas it was restricted to 1/34 B cell NHL other than PEL (P < 0.001; chi2 test). The Met protein expressed by PEL displays biochemical characteristics typical of Met expressed by other cell types and is capable of tyrosine autophosphorylation. By using a combination of immunological and biological assays, production and secretion of a functional HGF species was identified in all PEL cell lines analyzed. HGF stimulation of PEL cells rapidly induces Met tyrosine phosphorylation, demonstrating the functional integrity of the Met/HGF loop. Because of the well known mitogenic and motogenic properties of Met/HGF interactions, these data may bear implications for PEL growth and dissemination. Among B cell neoplasms, Met/HGF co-expression selectively clusters with PEL and, as demonstrated by previous studies, with multiple myeloma plasma cells, thus reinforcing the notion that PEL displays biologic similarities with tumors derived from late stages of B cell differentiation.

Hematopoietic growth factors in autologous transplantation

Hematopoietic growth factors (HGFs) sustain the survival, proliferation and differentiation of hematopoietic stem cells and some functions of mature blood cells. In man several HGFs have been characterised and cloned so far, and this has allowed investigators to confer the rationale for the clinical application of these molecules in hematology and oncology. In particular G-CSF and GM-CSF are currently utilised to abrogate the hematological toxicity of chemotherapy for standard and dose-intensified therapy, neutropenia following bone marrow and peripheral blood stem cell transplantation. Moreover there has recently been great interest in the ex vivo expansion of hematopoietic stem and progenitor cells for a variety of applications, such as in vitro tumor cell purging or for reducing the volume of blood processed by the leukapheresis. Several combinations of HGFs have been described to sustain the ex vivo survival and proliferation of these cells disclosing new opportunities in the field of stem cells transplants.

GAS6 inhibits granulocyte adhesion to endothelial cells

GAS6 is a ligand for the tyrosine kinase receptors Rse, Axl, and Mer, but its function is poorly understood. Previous studies reported that both GAS6 and Axl are expressed by vascular endothelial cells (EC), which play a key role in leukocyte extravasation into tissues during inflammation through adhesive interactions with these cells. The aim of this work was to evaluate the GAS6 effect on the adhesive function of EC. Treatment of EC with GAS6 significantly inhibited adhesion of polymorphonuclear cells (PMN) induced by phorbol 12-myristate 13-acetate (PMA), platelet-activating factor (PAF), thrombin, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), but not that induced by FMLP and IL-8. GAS6 did not affect adhesion to resting EC. Titration experiments showed that high concentrations of GAS6 were needed to inhibit PMN adhesion and that inhibition was dose-dependent at the concentration range of 0.1 to 1 microg/mL. One possibility was that high concentrations were needed to overwhelm the effect of endogenous GAS6 produced by EC. In line with this possibility, treatment of resting EC with soluble Axl significantly potentiated PMN adhesion. Analysis of localization of GAS6 by confocal microscopy and cytofluorimetric analysis showed that it is concentrated along the plasma membrane in resting EC and treatment with PAF induces depletion and/or redistribution of the molecule. These data suggest that GAS6 functions as a physiologic antiinflammatory agent produced by resting EC and depleted when proinflammatory stimuli turn on the proadhesive machinery of EC.

GAS6, the ligand of Axl and Rse receptors, is expressed in hematopoietic tissue but lacks mitogenic activity

GAS6, a gene previously identified as growth arrest specific, has been demonstrated to be the ligand of Axl, a novel tyrosine kinase receptor widely expressed in both normal and neoplastic hematopoietic tissue. We have observed previously that GAS6 mRNA was present in whole bone marrow. This preliminary finding prompted us to investigate the presence of GAS6 in hematopoietic tissue and the possible role of this molecule in controlling the proliferation of hematopoietic precursors. We report here that the protein GAS6 is diffusely present in hematopoietic tissue, both in stromal and in hematopoietic cells, and that, among these cells, positivity is observed in megakaryocytes and myelomonocytic precursors. Furthermore, our data suggest that GAS6 is not a growth factor for hematopoietic progenitors or stromal fibroblasts. Despite the fact that both the Axl receptor and its ligand, GAS6, are expressed in hematopoietic tissue, the biological role of their interactions remains to be determined.

[Prevention and treatment of febrile neutropenia]

Many chemotherapy regimens are associated with variable periods of myelosuppression. In cancer patients, neutropenia (less than 500 neutrophils/microL) is the most important risk factor for infections. The incidence and severity of infectious complications are related to depth and duration of neutropenia, with the highest risk if neutrophils are less than 100/microL for more than a week. The period required for neutrophil recovery is usually short with standard regimens, but prolonged after high dose chemotherapy followed by autologous bone marrow transplant (-ABMT) or peripheral blood stem cell (PBSC) infusion. Under these conditions, the administration of granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) accelerates neutrophil recovery and shortens the duration of hospitalization. In standard chemotherapy settings, prophylactic use of CSF's is a matter of debate. Several studies have reached contrasting conclusion, but, combining effectiveness and costs, it results that this use of CSF'S is not to be recommended unless the risk of infections (elderly patients, reduced marrow reserve) is high. The administration of G-CSF or GM-CSF to a febrile neutropenic patient (cfr CSF's therapy) shortens the duration of neutropenia, although no great clinical benefits are evident. Nevertheless the identification of subsets of patients with additional risk factors (i.e. absolute neutrophil count < 100/microL at the onset of fever or delayed neutrophil recovery) should be helpful in establishing the role of CSF's therapy. When prolonged periods of severe neutropenia (less than 500 neutrophils/microL) are expected, antibiotics should be prophylactically administered. Fluoroquinolones seem to be the optimal choice in heavily myelosuppressed patients (ie. bone marrow transplant recipients). Fluoroquinolones are effective in reducing the frequency of gram-negative bacteremia, but, because of incomplete coverage, gram-positive infections are becoming increasingly problematic. The association with an agent that can be absorbed orally, active against gram-positive cocci, seems to be an effective strategy. Fungal infections are an important cause of morbility and mortality in severely neutropenic patients. Safety and efficacy of antifungal triazoles and the lipid formulations of amphotericin B used prophylactically still require investigation. In patients at high risk for fungal infections, monitoring cultures are predictive for systemic mycoses and should guide prophylactic and therapeutic choices. The standard treatment of oncologic patients with potential infectious neutropenia complications is admission to the hospital and treatment with broad-spectrum intravenous antibiotics. Until third generation cephalosporin and carbapenems became available, most neutropenic febrile patients were treated with associations of an aminoglycoside plus a beta-lactam. Monotherapy with the new antibiotics has proven to be effective as an association therapy and offers advantages in terms of cost and tolerability. Whether or not vancomycin is included in the initial antibiotic regimen should be decided on the basis of epidemiological consideration (i.e. prevalence of meticillin-resistant Staphylococcus aureus or Staphylococcus mitis in certain centers). Antifungal therapy is indicated in neutropenic patients who remain febrile after one week of broad-spectrum antibiotics or have recurrent fever. Amphotericin B should be promptly administered in patients suspected of invasive mycoses. Selected patients with fever and neutropenia, that can be identified on the basis of reduced risk of severe complications, do not need hospitalization. In the first reports, outpatient treatment has proven to be effective, cost saving and well received by patients, but further studies are needed to accurately define low risk status and the optimal home antibiotic regimens.

IFN-gamma inhibits thrombin- and endotoxin-induced plasminogen activator inhibitor type 1 in human endothelial cells

The plasmin/plasminogen system of enzymes may be involved in leukocyte migration through the endothelial cell layer of the vascular wall during inflammatory processes associated with vascular injury, atherosclerosis, and sepsis. Synthesis of plasminogen activator inhibitor type 1 (PAI-1) by the endothelium may protect these cells and the subendothelial cell matrix from excessive degradation and retard leukocyte migration. We report in this work for the first time the down-regulation of both basal and thrombin- or endotoxin-induced PAI-1 in cultured human endothelial cells by the activated T cell product, IFN-gamma. Down-regulation of basal and thrombin- or endotoxin-induced endothelial PAI-1 protein by IFN-gamma was found to be both time and dose dependent. Decreases of up to 71% relative to thrombin- or endotoxin-treated controls, using an optimal IFN-gamma concentration of between 20 and 200 U/ml, were found for human macrovascular and microvascular endothelial cells. However, IFN-gamma did not appear to affect IL-1 alpha- and TNF-alpha-induced levels of PAI-1 protein or mRNA in these cells. Northern blot analysis paralleled protein results, showing decreases in specific endothelial cell thrombin- or LPS-induced PAI-1 mRNA expression, respectively, after incubation with IFN-gamma for 24 h. These results suggest a means by which the migration of circulating leukocytes through endothelial cell layers during inflammation may be facilitated.

IFN-gamma inhibits thrombin- and endotoxin-induced plasminogen activator inhibitor type 1 in human endothelial cells

The plasmin/plasminogen system of enzymes may be involved in leukocyte migration through the endothelial cell layer of the vascular wall during inflammatory processes associated with vascular injury, atherosclerosis, and sepsis. Synthesis of plasminogen activator inhibitor type 1 (PAI-1) by the endothelium may protect these cells and the subendothelial cell matrix from excessive degradation and retard leukocyte migration. We report in this work for the first time the down-regulation of both basal and thrombin- or endotoxin-induced PAI-1 in cultured human endothelial cells by the activated T cell product, IFN-gamma. Down-regulation of basal and thrombin- or endotoxin-induced endothelial PAI-1 protein by IFN-gamma was found to be both time and dose dependent. Decreases of up to 71% relative to thrombin- or endotoxin-treated controls, using an optimal IFN-gamma concentration of between 20 and 200 U/ml, were found for human macrovascular and microvascular endothelial cells. However, IFN-gamma did not appear to affect IL-1 alpha- and TNF-alpha-induced levels of PAI-1 protein or mRNA in these cells. Northern blot analysis paralleled protein results, showing decreases in specific endothelial cell thrombin- or LPS-induced PAI-1 mRNA expression, respectively, after incubation with IFN-gamma for 24 h. These results suggest a means by which the migration of circulating leukocytes through endothelial cell layers during inflammation may be facilitated.

Stimulation of PAI-1 expression in endothelial cells by cultured vascular smooth muscle cells

Regulation of endothelial cell (EC) plasminogen activator inhibitor type-1 (PAI-1), the primary physiological inhibitor of tissue-type plasminogen activator (TPA) and urokinase-type plasminogen activator (UPA), by various stimuli has been well characterized. We report the upregulation of secreted and intracellular PAI-1 in human umbilical ECs when cocultured with human smooth muscle cells (SMCs) on amniotic membranes or incubated with SMC conditioned medium (CM) under serum-free conditions as determined by enzyme-linked immunosorbent assay. Cocultured human umbilical vein ECs and SMCs, or human umbilical artery ECs and SMCs, displayed a 73% and 68% increase, respectively, in released PAI-1. SMC-derived stimulatory factor release showed tissue specificity, since only human aortic, umbilical vein, and umbilical artery SMCs upregulated PAI-1 synthesis, whereas SMCs from human mammary artery, pulmonary artery, and saphenous vein did not. Stimulation of EC PAI-1 by SMC CM was both time and concentration dependent, with as much as five- and fourfold increases in supernatants and lysates, respectively. PAI-1 synthesis and activity in ECs from other vascular beds were also upregulated by SMC CM. Northern blot analysis paralleled the protein results, showing as much as a 2.7-fold increase in specific EC PAI-1 mRNA expression after incubation with SMC CM for 8 hours. PAI-1 stimulatory activity in SMC CM was completely abolished by boiling or incubation with protamine sulfate and was reduced by transient acidification or heparin-Sepharose pretreatment by 33% or 48%, respectively. The stimulatory factor(s) appeared to have a molecular mass of 23 kD as determined by gel filtration.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon-alpha 2 counteracts interleukin-1 alpha-stimulated expression of urokinase-type plasminogen activator in human foreskin microvascular endothelial cells in vitro

We investigated the effect of interferon-alpha 2 (IFN-alpha 2) on interleukin-1 alpha (IL-1 alpha)-induced up-regulation of urokinase type plasminogen activator (u-PA) expression in human foreskin microvascular endothelial cells (HFMEC) and human umbilical vein endothelial cells (HUVEC) in vitro. When IFN-alpha 2 and IL-1 alpha were added to the cells simultaneously, IFN-alpha 2 inhibited IL-1 alpha-induced up-regulation of u-PA antigen in a dose- and time-dependent fashion in HFMEC, whereas in HUVEC no effect of IFN-alpha 2 on IL-1 alpha-induced u-PA was seen. IL-1 alpha-induced up-regulation of PAI-1 antigen in HFMEC was not counteracted by IFN-alpha 2. When IFN-alpha 2 was added to HFMEC 1 or 2 h after IL-1 alpha a significant inhibition in u-PA synthesis was seen, whereas when IFN-alpha 2 was added to the cells 8 h after IL-1 alpha no effect on the induction of u-PA synthesis by IL-1 alpha was seen. IFN-alpha 2 also inhibited significantly the IL-1 alpha stimulated up-regulation of specific u-PA mRNA expression. In conclusion, our data show that IFN-alpha 2 can counteract the IL-1 alpha-induced up-regulation of u-PA in a similar way as IFN-gamma. This effect, which seems to be specific for microvascular endothelial cells, could contribute to the modulation of endothelial cell-mediated extravascular proteolysis in processes such as wound healing, neovascularisation, and endothelial cell migration.

Effects of calcium- and ETA-receptor antagonists on endothelin-induced vasoconstriction and levels of endothelin in the human internal mammary artery

1. The effects of the ETA receptor antagonist BQ123 and dihydropyridine calcium antagonists on the vasoconstrictor effect of endothelin-1 (ET-1) were studied in human isolated internal mammary artery (IMA). The effect of the calcium antagonist, nisoldipine, on ET-1 levels has also been examined in cultured IMA endothelial cells (IMAEC). 2. The results showed that BQ123 and the calcium antagonists nisoldipine, isradipine, nitrendipine and nifedipine fully relaxed IMA precontracted with 3 nmol/L ET-1 with the EC50 values of 7.18 +/- 0.09 (-log mol/L) for BQ123, and 7.68 +/- 0.07, 7.02 +/- 0.12, 6.96 +/- 0.08 and 6.89 +/- 0.09 for the calcium antagonists, respectively. 3. Pretreatment of IMA with 10, 30, 100 and 300 nmol/L nisoldipine significantly depressed the maximal response (Max; 88.3 +/- 5.1, 75.2 +/- 4.9, 59.3 +/- 5.6 and 56.2 +/- 4.8% of maximal noradrenaline response versus 99.1 +/- 13.2% in control, P < 0.01) of IMA to ET-1 without a significant change in the EC50 values. 4. Pretreatment of IMA with 300 nmol/L BQ123 significantly increased both the EC50 (7.97 +/- 0.09 vs 8.36 +/- 0.08 in the control, P < 0.05) and the Max (138.1 +/- 10.2% vs the control, P < 0.01) of IMA to ET-1. 5. Incubation of IMAEC with nisoldipine for 7 h resulted in a dose-dependent (10(-8)-10(-5) mol/L) reduction up to 93.1% in ET levels in the conditioned media.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of endothelin levels by the dihydropyridine calcium antagonist nisoldipine and a 'natural factor' in cultured human endothelial cells

OBJECTIVE

Endothelin is thought to be related to cardiovascular disease. The purpose of this study was to determine whether endothelin levels could be reduced by a calcium antagonist and a 'natural factor'.

DESIGN

Since calcium ionophores can induce endothelin-1 messenger RNA synthesis in cultured endothelial cells, the calcium antagonist nisoldipine was used in this study to determine whether it could reduce endothelin levels. It has been reported that coculture of endothelial cells and smooth muscle cells from different species and different parts of the body can reduce endothelin levels. This study was also designed to determine whether coculture of the two cell types from the same species and the same section of an artery could reduce endothelin levels.

METHODS

Cultured endothelial cells from human umbilical artery (HUAEC) and umbilical vein (HUVEC) were treated with increasing concentrations of nisoldipine. HUAEC were cocultured with human umbilical artery smooth muscle cells (HUASMC). Endothelin levels were measured by a radioimmunoassay.

RESULTS

Incubation of the HUAEC with nisoldipine for either 7 or 24 h resulted in a dose-dependent (10(-8)-10(-5) mol/l) reduction in endothelin levels in the conditioned media. Endothelin levels in cell lysates were not detectable in either the absence or the presence of nisoldipine. This suggests that the reduction of endothelin levels in the media could be due to inhibition of endothelin synthesis. Under the same conditions, incubation of HUVEC with the same concentrations of nisoldipine produced a similar concentration-dependent reduction in endothelin levels. Endothelin levels were undetectable in the conditioned media from HUASMC. Coculture of HUAEC with HUASMC significantly reduced endothelin levels (P < 0.01) compared with HUAEC cultured alone.

CONCLUSIONS

Endothelin levels can be reduced by the calcium antagonist nisoldipine and a 'natural factor' associated with smooth muscle cells.

Atheromatous plaque macrophages produce plasminogen activator inhibitor type-1 and stimulate its production by endothelial cells and vascular smooth muscle cells

The capacity of macrophages to influence directly and indirectly fibrinolytic processes in atherosclerosis was studied using macrophages isolated from atherosclerotic plaques of patients undergoing surgical repair of distal aortic and femoral arteries. These cells were characterized by their morphology, adherence, esterase positivity, and expression of CD14 antigen. Production of plasminogen activator inhibitor type-1 (PAI-1) by plaque macrophages (6.7 +/- 2.7 ng/10(5) cells/24 hours [mean +/- SEM]) was significantly greater than PAI-1 production by blood monocytes isolated simultaneously from the same patients (1.8 +/- 1.5 ng/10(5) cells/24 hours). Production of tissue type plasminogen activator and urokinase type was not augmented compared to blood monocytes. Conditioned medium from cultured plaque macrophages significantly increased production of PAI-1 by endothelial cells (85 +/- 11% above basal) and vascular smooth muscle cells (25 +/- 10%) in vitro. This response was significantly greater than the response to monocyte-conditioned medium (endothelial cells 38 +/- 11%, vascular smooth muscle cells 2.5 +/- 2.0%). Stimulation of endothelial cell PAI-1 production by macrophage-conditioned medium was partially inhibitable by a monoclonal antibody to transforming growth factor-beta. Tissue type plasminogen activator production by endothelial cells and vascular smooth muscle cells was not affected by plaque macrophage- or monocyte-conditioned medium. Urokinase type plasminogen activator production by endothelial cells and vascular smooth muscle cells was undetectable in control medium and was augmented to similar levels in response to plaque macrophage- and monocyte-conditioned media. These results demonstrate upregulation of PAI-1 production by macrophages in atheromatous plaques and the capacity of soluble products from plaque macrophages to upregulate PAI-1 production by endothelial cells and vascular smooth muscle cells in vitro. These data suggest that macrophages in atherosclerotic plaques may inhibit thrombolysis both directly and indirectly by effects of their soluble products on endothelial cells and vascular smooth muscle cells.

Thrombin stimulates expression of tissue-type plasminogen activator and plasminogen activator inhibitor type 1 in cultured human vascular smooth muscle cells

The effect of thrombin on the fibrinolytic potential of human vascular smooth muscle cells (SMC) in culture was studied. SMC of different origin responded to thrombin treatment with a dose and time dependent increase in tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) levels in both cell lysates and conditioned media with maximum effects achieved at 10-20 IU/ml thrombin. PAI-1 antigen levels also increased in the extracellular matrix of thrombin treated SMC. PAI-2 levels in cell lysates of such SMC were not affected by thrombin. The effect was restricted to active thrombin, since DFP-thrombin and thrombin treated with hirudin showed no increasing effect on t-PA and PAI-1 levels in SMC. Enzymatically active thrombin also caused a four-fold increase in specific PAI-1 mRNA and a three-fold increase in t-PA mRNA. Furthermore we demonstrated the presence of high and low affinity binding sites for thrombin on the surface of SMC with a KD = 4.3 x 10(-10)M and 9.0 x 10(4) sites per cell and a KD = 0.6 x 10(-8) M and 5.8 x 10(5) sites per cell respectively. Thrombin could come in contact with SMC in case of vascular injury or following gap formation between endothelial cells. Our data support the idea that besides its known proliferative effect for SMC, thrombin could also modulate their fibrinolytic system.

Interleukin-4 stimulates expression of urokinase-type-plasminogen activator in cultured human foreskin microvascular endothelial cells

The effect of interleukin-4 (IL-4) on the fibrinolytic system of human microvascular and macrovascular endothelial cells in culture was studied. Only foreskin microvascular endothelial cells (EC) responded to IL-4 treatment with a dose- and time-dependent increase in urokinase-type plasminogen activator (u-PA) (control: 3.0 +/- 0.8 ng/10(5) cells/24 h; 200 U/mL IL-4: 6.7 +/- 0.8 ng/10(5) cells/24 h), whereas human macrovascular EC remained unaffected. A maximum effect was achieved with 200 U/mL IL-4. Little u-PA activity was detected in the conditioned media of human foreskin microvascular EC (HFMEC) treated without and with IL-4 before plasmin treatment (control: 0.03 +/- 0.003 IU/10(5) cells/20 h; 200 U/mL IL-4: 0.09 +/- 0.007 IU/10(5) cells/20 h). These values increased to 0.18 +/- 0.02 IU/10(5) cells/20 h and 0.53 +/- 0.04 IU/10(5) cells/20 h, respectively, after plasmin treatment, indicating that u-PA is released by HFMEC predominantly in its inactive precursor form single-chain u-PA (scu-PA). u-PA activity increased also in the cell lysates of HFMEC up to 2.5-fold after IL-4 treatment. Plasminogen activator inhibitor type-1 (PAI-1) levels produced by HFMEC remained unaffected by IL-4, whereas tissue-type plasminogen activator (t-PA) levels were slightly decreased when HFMEC were treated with IL-4. These findings were also reflected in the specific mRNA levels as determined by Northern blotting. u-PA-specific mRNA increased significantly in HFMEC in the presence of IL-4, whereas t-PA mRNA and PAI-1-specific mRNA in HFMEC and u-PA specific mRNA in human saphenous vein EC (HSVEC) remained unaffected by IL-4 treatment. Our findings suggest a role for IL-4 in the process of angiogenesis, in addition to its known proliferative effect on human microvascular EC, by increasing the fibrinolytic potential of such EC, thereby facilitating extracellular proteolysis and cell migration.

Cytokine regulation of the synthesis of plasminogen activator inhibitor-2 by human vascular endothelial cells. Comparison with plasminogen activator inhibitor-1 synthesis

Plasminogen activators are inhibited by plasminogen activator inhibitors-1 (PAI-1) and -2 (PAI-2). We describe the synthesis of PAI-2 by human vascular endothelial cells (EC) cultured from umbilical vein, saphenous vein and foreskin microvasculature in response to interleukin-1 alpha (IL-1 alpha) and tumour necrosis factor alpha (TNF alpha) and compare it with that of PAI-1. Both PAI-2 and PAI-1 were quantitated by ELISAs. PAI-2 was cell-associated while PAI-1 was secreted by EC. IL-1 alpha and TNF alpha increased the synthesis of PAI-2 and PAI-1 by EC in a dose-dependent manner. IL-1 alpha was a stronger stimulus for PAI-2 synthesis than TNF alpha, while both cytokines were equally effective for PAI-1. Northern blot analysis revealed similar changes in mRNA levels to those in antigen levels. PAI-2 synthesis by cytokine-stimulated EC may be important in thrombus formation and inflammation.

Gamma-interferon counteracts interleukin-1 alpha stimulated expression of urokinase-type plasminogen activator in human endothelial cells in vitro

The effect of gamma-interferon (gamma-IFN) on the interleukin-1 alpha (IL-1 alpha) induced stimulation of urokinase-type plasminogen activator (u-PA) expression in human foreskin microvascular endothelial cells (HFMEC) and in human umbilical vein endothelial cells (HUVEC) was investigated. When gamma-IFN and IL-1 alpha were added to the cells simultaneously, gamma-IFN inhibited the IL-1 alpha induced increase in u-PA antigen production in both HFMEC and HUVEC in a dose dependent fashion, with a maximum inhibitory effect achieved between 2.0 and 20.0 U/ml of gamma-IFN. Pretreatment of HFMEC with gamma-IFN for 1 hour before addition of IL-1 alpha resulted in a significant reduction in u-PA synthesis. However, when HFMEC were pretreated for 8 hours with gamma-IFN before the addition of IL-1 alpha the reduction in u-PA production was even more significant. When gamma-IFN was added to HFMEC 1 hour after IL-1 alpha, a significant inhibition in u-PA synthesis was seen. In contrast only a slight inhibition in IL-1 alpha induced u-PA production was seen when gamma-IFN was added to the cells 8 hours after IL-1 alpha. gamma-IFN also inhibited significantly the IL-1 alpha induced increase in u-PA specific mRNA in HUVEC and HFMEC.

Circulating anti-glomerular basement membrane antibodies in coeliac disease and epidermolysis bullosa acquisita

The demonstration of circulating anti-glomerular basement membrane (GBM) antibodies is almost diagnostic for anti-GBM disease and Goodpasture's syndrome. These antibodies are, however, occasionally present in SLE and diabetes, in association with IgA disease and membranous nephropathy and after transplantation in Alport's syndrome. In addition, we describe circulating anti-GBM antibodies in a research worker who handled GBM and in whom coeliec disease later developed, and in an individual with epidermolysis bullosa acquisita. Neither patient had impaired renal function nor an abnormal urinary sediment, suggesting either that these antibodies were of low affinity, or that additional factors are required for the pathogenesis of an aggressive glomerular lesion when circulating anti-GBM antibodies are present. In at least one of these individuals anti-GBM antibodies may have developed after the exposure of basement membrane collagen type IV to activated immunological mediators and cells.

Autoantibodies in systemic vasculitis

We have studied 495 sera that were referred to us from patients suspected on clinical and/or histological grounds to have a small vessel vasculitis. These sera were tested for antibodies against neutrophil cytoplasm antigens (anti-neutrophil cytoplasm antibodies, ANCA) using assays based on neutrophil acid extract, myeloperoxidase and elastase. Such antibodies are commonly found in Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA), and sometimes in other small vessel vasculitides. One hundred and twenty-six of these sera (25%) were positive in the acid extract ELISA, 68 (14%) in the assay for anti-myeloperoxidase antibodies and 35 (16%) in the assay for anti-elastase antibodies. A total of 166 sera (34%) were positive for antibodies against neutrophil cytoplasm constituents. No ANCA, anti-myeloperoxidase or anti-elastase antibodies were detected in 26 convalescent sera from patients either with WG or MPA, or who had previously been positive. The mean time between positive and negative sera was eight weeks (range three weeks to six months) and three out of three who relapsed again developed ANCA of the same specificity as the original sera. Of the 228 sera also tested for anti-GBM antibodies, 13 (5.7%) were positive. All these contained antibodies against neutrophil cytoplasm constituents (three against the acid extract, eight against myeloperoxidase and two against elastase). Forty-nine of the 74 sera (66%) tested for ANA were positive. Twenty-nine (39%) had a speckled and 20 (27%) had a homogeneous pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

The non-collagenous domains of the alpha 3 and 4 chains of type IV collagen and their relationship to the Goodpasture antigen

The Goodpasture antigen is the target recognized by anti-glomerular basement membrane (GBM) antibodies in anti-GBM disease or Goodpasture's syndrome. This structure is present in all normal GBM, but when serum containing anti-GBM antibodies is used to examine renal tissue from most males with classical Alport's syndrome, the Goodpasture antigen appears to be missing. The nature of the Goodpasture antigen is uncertain although it has been putatively and controversially localized to the non-collagenous domain of a novel type IV collagen chain (alpha 3) by one group, and a short peptide sequence has been published (M2). We have performed several experiments to determine whether M2 represents the Goodpasture antigen and we have also studied the corresponding sequence of the alpha 4 chain of type IV collagen (M3). Firstly, we demonstrated by polymerase chain reaction (PCR) amplification using specific priming oligonucleotides that mRNAs corresponding to M2 and M3 were found within the kidney and that the published sequences were correct. When heterologous antibodies were raised against M2 and M3 these bound specifically to GBM in an ELISA based on collagenase-digested basement membrane and this binding could be inhibited by incubation with collagenase-digested GBM but not with ovalbumin. On further examination of the target molecules using Western blots, the anti-M2 antibody bound to a single high molecular weight band of collagen-digested GBM in contrast to the anti-M3 antibody that bound to the same bands as Goodpasture serum. We then established ELISAs for anti-M2 and anti-M3 activity using the peptides M2 and M3. While rabbit anti-M2 and M3 antibodies bound specifically to their respective peptides in these ELISAs, there was no binding of three high titre Goodpasture's syndrome sera or two sera from Alport's syndrome patients with inhibitable anti-GBM antibody post-renal transplant. We have shown that the sequences of M2 and M3 correspond to proteins present within the collagenase-resistant part of the GBM, suggesting that these do represent parts of novel type IV collagen chains. However, sera containing anti-GBM antibodies did not bind to either peptide in solid-phase ELISAs, and these antibodies may recognize a different peptide sequence, features of the tertiary structure of these peptides or interactions between collagen chains.

Diverse target antigens recognized by circulating antibodies in anti-neutrophil cytoplasm antibody-associated renal vasculitides

Antibodies that are directed against cytoplasmic constituents of neutrophils and monocytes (anti-neutrophil cytoplasm antibodies, ANCA) have been described in Wegener's granulomatosis, microscopic polyarteritis (MPA) and some cases of segmental necrotizing glomerulonephritis (SNGN). Other antibodies occasionally described in Wegener's granulomatosis and MPA include anti-nuclear antibodies (ANA) and anti-glomerular basement membrane (GBM) antibodies. We have studied the diversity of the corresponding antigens in ANCA-associated renal diseases. Sera from 46 patients with active histologically proven Wegener's granulomatosis, MPA and SNGN were tested for ANCA by indirect immunofluorescent examination of normal peripheral blood neutrophils. Thirty-four sera (74%) were positive; 16 were associated with diffuse cytoplasmic staining (cANCA) and 18 with perinuclear staining (pANCA). In addition, five demonstrated antineutrophil-specific nuclear staining (ANNA). On Western blotting of the neutrophil extract, five sera recognized a 29-kD molecule recently identified as neutrophil proteinase 3. Two sera with typical cANCA bound to molecules of 36, 38 and 116 kD and another to a molecule of 22 kD. The final serum associated with pANCA bound to a molecule of about 12 kD. Thirteen sera out of 46 (28%) tested in an ELISA contained anti-myeloperoxidase antibodies; 10 of these were associated with pANCA and two others with ANNA. Three sera of 17 (18%) tested contained anti-elastase antibodies; these also contained anti-myeloperoxidase antibodies and were associated with pANCA. However, eight sera with pANCA were negative for anti-myeloperoxidase antibodies and three of these were also negative for anti-elastase antibodies, suggesting further unidentified target antigen or antigens associated with the pANCA. Fifteen of the 34 sera positive for ANCA also demonstrated anti-nuclear staining on Hep-2 cells (53%) in a speckled, homogeneous, or nucleolar pattern. ANA were significantly associated with the presence of pANCA (P less than 0.01), and levels of ANA and ANCA fell in parallel after treatment. One serum with a pANCA was also positive for anti-GBM antibodies. Inhibition studies using ELISAs for anti-GBM antibodies indicated that there was no cross-reactivity between target molecules recognized by these antibodies. The diversity of target molecules recognized by ANCA suggests that cross-reactivity with bacterial structures is less likely as the primary aetiological event in the development of these antibodies than tissue destruction; and that cross-reactivity with vascular endothelium is also unlikely as the pathogenetic basis of vessel disease.

Two ELISAs to detect anti-neutrophil cytoplasm antibodies (ANCA) in various vasculitides

Anti-neutrophil cytoplasm antibodies (ANCA) are present in the serum of patients with Wegener's granulomatosis, microscopic polyarteritis, and some other small vessel vasculitides. There are at least 2 different anti-neutrophil cytoplasm antibodies identified by their distinctive cytoplasmic staining patterns on indirect immunofluorescence examination. The only antigen identified to date is myeloperoxidase which has a perinuclear distribution on alcohol-fixed neutrophils and monocytes. We have established an ELISA that detects all anti-neutrophil cytoplasm antibodies and one specific for anti-myeloperoxidase antibodies. In the ELISA for anti-neutrophil cytoplasm antibodies, all sera with diffuse cytoplasmic or perinuclear neutrophil staining on indirect immunofluorescence examination bound at levels greater than the normal range (34%, m + 4SD). Three convalescent sera that were negative by indirect immunofluorescence examination were also negative in the assay. Positive sera could be detected at a dilution of 2 and inhibition studies showed that the binding was specific for the neutrophil extract. However, the presence of anti-neutrophil antibodies (ANA), anti-mitochondrial antibodies or immune complexes resulted occasionally in binding in the positive range. Where positive binding was noted in non-vasculitic segmental necrotizing glomerulonephritis, the binding could not be inhibited by pre-incubation with the neutrophil extract. The ELISA for ANCA is a sensitive, objective screening technique that can be performed in parallel with the assay for anti-glomerular basement antibodies to exclude the presence of anti-neutrophil cytoplasm antibodies in patients presenting with rapidly progressive glomerulonephritis. The ELISA for anti-myeloperoxidase antibodies may identify a subset of patients with distinct clinical or prognostic features.