Prostacyclin synthesis induced in vascular cells by interleukin-1

Altered IL-32 Signaling in Abdominal Aortic Aneurysm

INTRODUCTION AND OBJECTIVE

Interleukin (IL)-32 is a pro-inflammatory cytokine not previously studied in relation to abdominal aortic aneurysm (AAA). The aim of this study was to elucidate the expression and localization of IL-32 in AAA.

METHODS

Expression and localization of IL-32 in human aortic tissue was studied with immunohistochemical analysis and Western blot (AAA: n = 5; controls: n = 4). ELISA was used to measure IL-32 in human plasma samples (AAA: n = 140; controls: n = 37) and in media from cultured peripheral blood mononuclear cells (PBMCs) from 3 healthy donors. IL-32 mRNA in PBMCs, endothelial cells, aortic smooth muscle cells (SMCs), and aortic tissue samples of AAA (n = 16) and control aortas (n = 9) was measured with qPCR.

RESULTS

IL-32 was predominantly expressed in SMCs and T-cell-rich areas. Highest mRNA expression was observed in the intima/media layer of the AAA. A weaker protein expression was detected in non-aneurysmal aortas. Expression of IL-32 was confirmed in isolated T cells, macrophages, endothelial cells, and SMCs, where expression was also inducible by cytokines such as interferon-γ. There was no difference in IL-32 expression in plasma between patients and controls.

CONCLUSION

IL-32 signaling is altered locally in AAA and could potentially play an important role in aneurysm development. Further studies using animal models would be helpful to study its potential role in AAA disease.

Analysis of Inflammatory Mediators and Peritoneal Permeability to Macromolecules Shortly before the Onset of Overt Peritonitis in Patients Treated with CAPD

Objective

To investigate whether changes in peritoneal membrane characteristics and inflammatory mediators in dialysate precede the onset of overt infection during continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis.

Design

CAPD patients with a high peritonitis incidence stored every night bag at 4°C. Routinely, each bag was thrown away after two days. Only if patients developed peritonitis, all bags were delivered for study. Thus, two night bags immediately prior to the first peritonitis bag were available for analysis. A control study was done 14 days after recovery. Dialysate samples were measured for TNFα, IL-6, PGE2, 6-keto-PGF lα’ TxB2, and serum proteins. The clearance of β2-microglobulin was used as an indicator of the effective peritoneal surface area. The intrinsic peritoneal permeability was characterized by the restriction coefficient.

Results

Eight episodes occurred in 5 patients. The night dwells available prior to the first peritonitis effluent were drained maximally nine dwells and minimally one dwell before the first peritonitis bag. Dialysate leukocyte counts exceeded 100 × 106/L only on the day of manifest infection. However, bacterial cultures were already positive at least one day before overt infection in four episodes and in three of these cases two days before. No changes were observed prior to peritonitis for the clearance of β2-microglobulin or the restriction coefficient. In contrast to these permeability characteristics, the cytokines, TNFα and, though less significant, also IL-6, were increased in dialysate one day prior to overt infection, when compared to the values obtained at the control investigation. This was especially evident in effluents drained no longer than two dwells before the first peritonitis bag. Prostaglandin concentrations in dialysate were not different before the onset of manifest peritonitis from the values measured after recovery.

Conclusion

In this study, the increased effective peritoneal surface area and intrinsic peritoneal permeability during acute infection appeared to be preceded by elevations in the cytokines TNFα and, to a lesser extent, IL-6. These increments occurred only very shortly before the onset of clinical symptoms.

Wandering pathways in the regulation of innate immunity and inflammation

Tumor-associated macrophages (TAM) have served as a paradigm of cancer-related inflammation. Moreover, investigations on TAM have led to the dissection of macrophage plasticity and polarization and to the discovery and analysis of molecular pathways of innate immunity, in particular cytokines, chemokines and PTX3 as a prototypic fluid phase pattern recognition molecule. Mechanisms of negative regulation are complex and include decoy receptors, receptor antagonists, anti-inflammatory cytokines and the signalling regulator IL-1R8. In this review, topics and open issues in relation to regulation of innate immunity and inflammation are discussed: 1) how macrophage and neutrophil plasticity and polarization underlie diverse pathological conditions ranging from autoimmunity to cancer and may pave the way to innovative diagnostic and therapeutic approaches; 2) the key role of decoy receptors and negative regulators (e.g. IL-1R2, ACKR2, IL-1R8) in striking a balance between amplification of immunity and resolution versus uncontrolled inflammation and tissue damage; 3) role of humoral innate immunity, illustrated by PTX3, in resistance against selected microbes, regulation of inflammation and immunity and tissue repair, with implications for diagnostic and therapeutic translation.

Review: Infection, fever, and exogenous and endogenous pyrogens: some concepts have changed

For many years, it was thought that bacterial products caused fever via the intermediate production of a host-derived, fever-producing molecule, called endogenous pyrogen (EP). Bacterial products and other fever-producing substances were termed exogenous pyrogens. It was considered highly unlikely that exogenous pyrogens caused fever by acting directly on the hypothalamic thermoregulatory center since there were countless fever-producing microbial products, mostly large molecules, with no common physical structure. In vivo and in vitro, lipopolysaccharides (LPSs) and other microbial products induced EP, subsequently shown to be interleukin-1 (IL-1). The concept of the `endogenous pyrogen' cause of fever gained considerable support when pure, recombinant IL-1 produced fever in humans and in animals at subnanomolar concentrations. Subsequently, recombinant tumor necrosis factor-α (TNF-α), IL-6 and other cytokines were also shown to cause fever and EPs are now termed pyrogenic cytokines. However, the concept was challenged when specific blockade of either IL-1 or TNF activity did not diminish the febrile response to LPS, to other microbial products or to natural infections in animals and in humans. During infection, fever could occur independently of IL-1 or TNF activity. The cytokine-like property of Toll-like receptor (TLR) signal transduction provides an explanation by which any microbial product can cause fever by engaging its specific TLR on the vascular network supplying the thermoregulatory center in the anterior hypothalamus. Since fever induced by IL-1, TNF-α, IL-6 or TLR ligands requires cyclooxygenase-2, production of prostaglandin E2 (PGE 2) and activation of hypothalamic PGE2 receptors provides a unifying mechanism for fever by endogenous and exogenous pyrogens. Thus, fever is the result of either cytokine receptor or TLR triggering; in autoimmune diseases, fever is mostly cytokine mediated whereas both cytokine and TLR account for fever during infection.

Recombinant interleukin-1β dilates steelhead trout coronary microvessels: effect of temperature and role of the endothelium, nitric oxide and prostaglandins

Interleukin (IL)-1β is associated with hypotension and cardiovascular collapse in mammals during heat stroke, and the mRNA expression of this pro-inflammatory cytokine increases dramatically in the blood of Atlantic cod (Gadus morhua) at high temperatures. These data suggest that release of IL-1β at high temperatures negatively impacts fish cardiovascular function and could be a primary determinant of upper thermal tolerance in this taxa. Thus, we measured the concentration-dependent response of isolated steelhead trout (Oncorhynchus mykiss) coronary microvessels (<150 μm in diameter) to recombinant (r) IL-1β at two temperatures (10 and 20°C). Recombinant IL-1β induced a concentration-dependent vasodilation with vessel diameter increasing by approximately 8 and 30% at 10(-8) and 10(-7) mol l(-1), respectively. However, this effect was not temperature dependent. Both vessel denudation and cyclooxygenase blockade (by indomethacin), but not the nitric oxide (NO) antagonist L-NIO, inhibited the vasodilator effect of rIL-1β. In contrast, the concentration-dependent dilation caused by the endothelium-dependent calcium ionophore A23187 was completely abolished by L-NIO and indomethacin, suggesting that both NO and prostaglandin signaling mechanisms exist in the trout coronary microvasculature. These data: (1) are the first to demonstrate a functional link between the immune and cardiovascular systems in fishes; (2) suggest that IL-1β release at high temperatures may reduce systemic vascular resistance, and thus, the capacity of fish to maintain blood pressure; and (3) provide evidence that both NO and prostaglandins play a role in regulating coronary vascular tone, and thus, blood flow.

There is more than one interleukin 1

In 1972, Gery and co-workers(1) detected a factor that promotes murine thymocyte proliferation in culture supernatants of human peripheral blood adherent leukocytes. This factor is active across species lines, does not support the growth of interleukin 2 (IL-2)-dependent lymphocyte lines, is produced by monocytic rather than lymphocytic leukocytes, and has subsequently been termed interleukin 1 (IL- 1)(2). More recently, it has become evident that IL-1 activities can be produced by virtually every nucleated cell type and, in addition, IL-1 has been reported to have stimulatory effects on the growth and differentiation of numerous cell types. In this review, Joost Oppenheim and his colleagues discuss the biochemical characteristics, gene cloning, cell sources, biological properties and actions of IL-1, and give reasons why this pleitotropic, nonspecific hormone-like cytokine is of considerable concern to immunologists.

IL-1β: an important cytokine associated with febrile seizures?

Febrile seizures (FSs) are the most common convulsions in childhood. Studies have demonstrated a significant relationship between a history of prolonged FSs during early childhood and temporal sclerosis, which is responsible for intractable mesial temporal lobe epilepsy. It has been shown that interleukin-1β (IL-1β) is intrinsically involved in the febrile response in children and in the generation of FSs. We summarize the gene polymorphisms, changes of IL-1β levels and the putative role of IL-1β in the generation of FSs. IL-1β could play a role either in enhancing or in reducing neural excitability. If the enhancing and reducing effects are balanced, an FS does not occur. When the enhancing effect plays the leading role, an FS is generated. A mild imbalance can cause simple FSs while a severe imbalance can cause complex FSs and febrile status epilepticus. Therefore, anti-IL-1β therapy may help to treat FSs.

Endothelial cell regulation of leukocyte infiltration in inflammatory tissues

Endothelial cells play an important, active role in the onset and regulation of inflammatory and immune reactions. Through the production of chemokines they attract leukocytes and activate their adhesive receptors. This leads to the anchorage of leukocytes to the adhesive molecules expressed on the endothelial surface. Leukocyte adhesion to endothelial cells is frequently followed by their extravasation. The mechanisms which regulate the passage of leukocytes through endothelial clefts remain to be clarified. Many indirect data suggest that leukocytes might transfer signals to endothelial cells both through the release of active agents and adhesion to the endothelial cell surface. Adhesive molecules (such as PECAM) on the endothelial cell surface might also ‘direct’ leukocytes through the intercellular junction by haptotaxis. The information available on the molecular structure and functional properties of endothelial chemokines, adhesive molecules or junction organization is still fragmentary. Further work is needed to clarify how they interplay in regulating leukocyte infiltration into tissues.

Sensory pulpal nerve fibres and trigeminal ganglion neurons express IL-1RI: a potential mechanism for development of inflammatory hyperalgesia

AIM

To localize interleukin-1 receptor type I (IL-1RI) in rat dental pulp and trigeminal ganglion (TG) and to test the hypothesis that pulpal inflammation increases neuronal expression of IL-1RI.

METHODOLOGY

Female Wistar rats were subjected to unilateral pulp exposures in the maxillary and mandibular first molars, whereas the contralateral jaws served as untreated controls. Seven days later the animals were transcardiacally perfused and the jaws and the TGs were removed and prepared for immunohistochemistry. Immunoreactivity for IL-1RI was examined alone (DAB) and together with calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), CD31 or CD34 by multiple-labelling immunofluorescence. Quantification of IL-1RI-immunoreactive (-IR) cells in the maxillary and mandibular division of the ganglion was performed in parasagittal immunoreacted sections of the right and left TGs. Data were analysed with Mann-Whitney Rank Sum test (P < 0.05).

RESULTS

Interleukin-1 receptor type I was found on sensory (CGRP-IR) and sympathetic (NPY-IR) nerve fibres and on blood vessels (CD31- and CD34-IR) in the dental pulp. It was also localized on sensory neurons and axons in the TG. Pulpal inflammation significantly increased the expression of IL-1RI in the TG (P < 0.001).

CONCLUSIONS

The localization of IL-1RI on sensory nerve fibres and its up-regulation in TG neurons during pulpal inflammation may imply a direct effect of IL-1 in pulpal nociception. The presence of IL-1RI on sympathetic nerve fibres and on blood vessels may indicate a vasoactive role of the same cytokine in the pulp.

IL-32-dependent effects of IL-1beta on endothelial cell functions

Increasing evidence demonstrates that interleukin (IL)-32 is a pro-inflammatory cytokine, inducing IL-1alpha, IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and chemokines via nuclear factor (NF)-kappaB, p38 mitogen-activated protein kinase (MAPK), and activating protein (AP)-1 activation. Here we report that IL-32 is expressed and is also functional in human vascular endothelial cells (EC) of various origins. Compared with primary blood monocytes, high levels of IL-32 are constitutively produced in human umbilical vein EC (HUVEC), aortic macrovascular EC, and cardiac as well as pulmonary microvascular EC. At concentrations as low as 0.1 ng/ml, IL-1beta stimulated IL-32 up to 15-fold over constitutive levels, whereas 10 ng/ml of TNFalpha or 100 ng/ml of lipopolysaccharide (LPS) were required to induce similar quantities of IL-32. IL-1beta-induced IL-32 was reduced by inhibition of the IkappaB kinase-beta/NF-kappaB and ERK pathways. In addition to IL-1beta, pro-coagulant concentrations of thrombin or fresh platelets increased IL-32 protein up to 6-fold. IL-1beta and thrombin induced an isoform-switch in steady-state mRNA levels from IL-32alpha/gamma to beta/epsilon. Adult EC responded in a similar fashion. To prove functionality, we silenced endogenous IL-32 with siRNA, decreasing intracellular IL-32 protein levels by 86%. The knockdown of IL-32 resulted in reduction of constitutive as well as IL-1beta-induced intercellular adhesion molecule-1 (ICAM-1) (of 55% and 54%, respectively), IL-1alpha (of 62% and 43%), IL-6 (of 53% and 43%), and IL-8 (of 46% and 42%). In contrast, the anti-inflammatory/anti-coagulant CD141/thrombomodulin increased markedly when IL-32 was silenced. This study introduces IL-32 as a critical regulator of endothelial function, expanding the properties of this cytokine relevant to coagulation, endothelial inflammation, and atherosclerosis.

Effects of tumour necrosis factor and related cytokines on vascular endothelial cells

Tumour necrosis factor (TNF) and related cytokines have been found to alter the phenotype of vascular endothelial cells so as to promote coagulation, inflammation and immunity. We have used recombinant human TNF, lymphotoxin (LT), interleukin 1 alpha (IL-1 alpha) and interleukin 1 beta (IL-1 beta) to study and compare the effects of these molecules on cultured human endothelial cells (HEC). All four mediators cause HEC monolayers to reorganize from an epithelioid to a fibroblastoid morphology. Reorganization is slow (days), reversible upon cytokine withdrawal and enhanced by co-addition of immune interferon. Coincident with morphological change, TNF and LT (but not IL-1 alpha or IL-1 beta) cause a marked increase in HLA-A, B mRNA and antigen expression. TNF and LT also induce a slow increase in the mRNA levels and cell-surface expression of IL-1 species. All four cytokines have been reported to enhance HEC adhesiveness for lymphocytes and inflammatory leucocytes; these changes temporally coincide with a rapid (hours) and sustained increase in expression of intercellular adhesion molecule 1 (ICAM-1), and with a rapid but transient de novo expression of an endothelial-leucocyte adhesion molecule (detected by antibody H4/18), respectively. TNF and LT induce reciprocal tachyphylaxis for the reinduction of H4/18 binding but do not inhibit induction by IL-1 alpha and IL-1 beta; similarly, IL-1 alpha and IL-1 beta induce reciprocal tachyphylaxis but do not inhibit TNF or LT. We have used the binding of H4/18 to explore the mechanism of action of TNF. Tumour-promoting phorbol esters, but not agents which increase cytoplasmic calcium concentrations, were found to induce binding, suggesting a possible involvement of the protein kinase C pathway in the response of HEC to TNF. Cells pretreated for 24 hours with phorbol esters cannot be reinduced to express H4/18 binding by phorbol esters yet retain full responsiveness to TNF. Thus TNF also appears to act on HEC through a pathway independent of protein kinase C activation. Collectively, these effects of TNF and related cytokines may be understood as examples of endothelial cell activation.

Effect of Ibuprofen on Interleukin-1??-Induced Abnormalities in Hemodynamics and Oxygen Metabolism in Rabbits

We showed previously that the administration of interleukin (IL)-1beta induces circulatory shock and impairs the oxygen consumption (VO2)/oxygen delivery (DO2) relation by increasing the slope of the supply-independent line in rabbits. We tested the effect of ibuprofen, a specific inhibitor of the development of shock in this model, on the VO2/DO2 abnormality. Eighteen rabbits were divided randomly into three groups (n = 6 each) and intravenously given 10 microg/kg of IL-1beta alone or 10 microg/kg of IL-1beta followed by 10 mg/kg of ibuprofen or saline (control). All rabbits were subjected to stepwise cardiac tamponade by inflation of a handmade balloon placed into the pericardial sac to reduce DO2. The VO2/DO2 relation was then analyzed by the dual line method. The IL-1beta group had a significantly lower mean arterial pressure than that of the other groups before cardiac tamponade, and this reduction in mean arterial pressure was suppressed completely by treatment with ibuprofen. The cardiac index did not differ between groups. The slope of the supply-independent line was increased significantly by administration of IL-1beta, and this increase was attenuated significantly by treatment with ibuprofen (IL-1beta only: y = 0.14x + 6.1, ibuprofen: y = 0.06x + 8.5, control: y = 0.01x + 9.0). We conclude that ibuprofen reversed the IL-1beta-induced shock by restoring the systemic vascular resistance to normal and thereby normalized the VO2/DO2 relation in the supply-independent range of DO2.

Immune responses in cancer

The complex of humoral factors and immune cells comprises two interleaved systems, innate and acquired. Immune cells scan the occurrence of any molecule that it considers to be nonself. Transformed cells acquire antigenicity that is recognized as nonself. A specific immune response is generated that results in the proliferation of antigen-specific lymphocytes. Immunity is acquired when antibodies and T-cell receptors are expressed and up-regulated through the formation and release of lymphokines, chemokines, and cytokines. Both innate and acquired immune systems interact to initiate antigenic responses against carcinomas. A new approach to the treatment of cancer has been immunotherapy, which aims to up-regulate the immune system in order that it may better control carcinogenesis. Currently, several forms of immunotherapy that use natural biological substances to activate the immune system are being explored therapeutically. The various forms of immunotherapy fall into three main categories: monoclonal antibodies, immune response modifiers, and vaccines. While these modalities have individually shown some promise, it is likely that the best strategy to combat cancer may require multiple immunotherapeutic strategies in order to demonstrate benefit in different patient populations. It may be that the best results are obtained with vaccines in combination with a variety of immunotherapy combinations. Another potent strategy may be in combining with more traditional cancer drugs as evidenced from the benefit derived from enhancing the efficacy of chemotherapy with cytokines. Through such concerted efforts, a durable, therapeutic antitumour immune response may be achieved and maintained over the course of a patient's lifespan.

ZO-1 redistribution and F-actin stress fiber formation in pulmonary endothelial cells after thermal injury

BACKGROUND

In response to isolated inflammatory stimuli, changes in endothelial cell morphology that enhance paracellular flow of solutes result from F-actin stress fiber formation, myosin phosphorylation, and actin anchoring protein (ZO-1) modifications. We hypothesized that myosin light chain kinase inhibition would diminish burn-enhanced endothelial monolayer permeability by secondarily preventing F-actin and actin anchoring protein rearrangements.

METHODS

Human pulmonary microvascular endothelial cells were treated for 4 hours with 20% human burn serum (isolated from patients with > 45% total body surface area thermal injury or healthy volunteers). Select cultures were pretreated with myosin light chain kinase inhibitors (ML-9). Permeability was assessed by migration of bovine serum albumin across cell monolayers. Cells were stained with rhodamine-phalloidin and anti-ZO-1 antisera and examined by means of confocal microscopy.

RESULTS

Burn serum significantly enhanced monolayer permeability to albumin, whereas pretreatment with ML-9 limited this effect. Control cells maintained cortical F-actin and peripheral ZO-1 distributions (1a, b), whereas burn serum induced transcellular F-actin stress fiber formation and a diffuse ZO-1 staining (2a, b). ML-9 prevented burn-induced actin rearrangements, but not the diffuse redistribution of ZO-1.

CONCLUSION

These data demonstrate that endothelial F-actin stress fiber formation and ZO-1 redistribution contribute to postburn loss of pulmonary endothelial monolayer integrity. Although myosin phosphorylation appears to be required for endothelial F-actin stress fiber formation, redistribution of actin-membrane anchoring proteins appears to be regulated independently after thermal injury.

Kallikrein cascade and cytokines in inflamed joints

Rheumatoid arthritis is a chronic multi-system disease of unknown aetiology. The current hypothesis is that an unknown antigen triggers an autoimmune response in a genetically susceptible individual. The predominant pathological change is that of an inflammatory synovitis, characterised by cellular infiltrates and angiogenesis, with subsequent bone and cartilage destruction. These pathological changes are as a result of the activation of a variety of cells, inflammatory mediators, and effector molecules. The pro-inflammatory kinins and cytokines appear to play a central role in the pathogenesis of rheumatoid arthritis. Sufficient evidence exists that establishes a key role for the kallikrein-kinin cascade in inflamed joints. In addition, there appears to be an inter-relationship between cytokines and kinins in the inflammatory process. Kinins induce the release of cytokines, and cytokines have been shown to augment the effects of kinins. This may lead to an enhancement and perpetuation of the inflammatory process. In this review, we report a first study, correlating markers of disease with the kallikrein-kinin cascade and with cytokines.

Anti-ovine interleukin-1beta monoclonal antibody immunotherapy in an ovine model of gram-negative septic shock

OBJECTIVE

To investigate the efficacy of an anti-ovine interleukin-1beta monoclonal antibody to ameliorate pathophysiological derangements and improve survival in an ovine model of gram-negative septic shock.

DESIGN

Prospective, placebo-controlled, interventional study (24-hr study period).

SETTING

University hospital animal research laboratory.

SUBJECTS

Ten awake, mature female sheep.

INTERVENTIONS

Seven milligrams per kilogram of intravenous anti-ovine interleukin-1beta immunoglobin G1 monoclonal antibody (anti-interleukin-1beta group, n = 5) or equivalent amount of protein (5% human albumin; control group, n = 5) was infused over 1 hr (time-zero minus 1 hr to time-zero) and followed by an intravenous LD100 live Escherichia coli infusion (time-zero to time-zero plus 1 hr). Normal saline, maintenance and boluses to maintain baseline filling pressures, and gentamicin, 3 mg/kg intravenous, at time-zero plus 2 and time-zero plus 13 hrs.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and oxygen transport indexes as well as hematological, biochemical, cytokine (interleukin-1beta, tumor necrosis factor-alpha), and endotoxin measurements were performed at baseline (time-zero minus 1 hr), on completion of the monoclonal antibody/placebo (time-zero) and E. coli (time-zero plus 1 hr) infusions, and at multiple time points thereafter (time-zero plus 1.5 hrs to time-zero plus 24 hrs). Baseline data were not different between the treatment groups. From time-zero plus 1.5 hrs onward, in the anti-interleukin-1beta group, there was a sustained increase in mean arterial pressure, decreased peripheral vasodilation, and an attenuated metabolic acidosis, relative to the control group (p < or = .01, repeated-measures analysis of variance). Predicted percentage increases in mean arterial pressure and systemic vascular resistance index relative to the control group were 35% and 40%, respectively. Resuscitation fluid requirements were also decreased: anti-interleukin-1beta group, 4.1 +/- 2.9 mL x kg(-1) x hr(-1); control group, 10.6 +/- 1.8 mL x kg(-1) x hr(-1) (p < or = .01, Student's t-test). Survival was not different (anti-interleukin-1beta group, 40%; control group, 0%; p > .01, log-rank test).

CONCLUSIONS

Adjunctive therapy with anti-ovine interleukin-1beta monoclonal antibody in ovine gram-negative septic shock was associated with improved hemodynamic performance. However, the beneficial effects were incomplete and survival was not significantly improved.

Lysophosphatidylcholine inhibits the expression of prostacyclin stimulating factor in cultured vascular smooth muscle cells

We have cloned a prostacyclin (PGI2) stimulating factor (PSF), which stimulates PGI2 production by vascular endothelial cells. Previous study demonstrated the reduced PSF expression in the coronary arteries from the patients with ischemic heart disease. To clarify the mechanism of reduced PSF expression in atherosclerosis, we examined the effect of lysophosphatidylcholine (lysoPC), a main component of oxidized low density lipoprotein (LDL), on PSF expression in cultured vascular smooth muscle cells. LysoPC reduced PSF expression dose-dependently. Whereas neither phosphatidylcholine nor native LDL affects the PSF expression. Calphostin C, a protein kinase C (PKC) inhibitor, restored the reduction of PSF expression by lysoPC. These results suggest that lysoPC-induced reduction of PSF expression is mediated by PKC activation and is playing a role in the initiation and progression of atherosclerotic lesions.

Polymorphisms for interleukin-1 beta (IL-1 beta)-511 promoter, IL-1 beta exon 5, and IL-1 receptor antagonist: nonassociation with endometriosis

PURPOSE

We aimed to investigate if interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1Ra) gene polymorphism could be used as markers of susceptibility in endometriosis.

MATERIALS AND METHODS

Women were divided into two groups: 1) endometriosis (n = 120); 2) nonendometriosis groups (n = 103). Polymorphisms for IL-1 beta-511 promoter, IL-1 beta exon 5, and IL-1Ra were detected by polymerase chain reaction. Genotypes and allelic frequencies for these polymorphisms in both groups were compared.

RESULTS

Proportions of different IL-1 and IL-1Ra polymorphisms in both groups were nonsignificantly different. Proportions of C homozygote/heterozygote/T homozygote for IL-1 beta-511 promoter in both groups were 1) 21.6/59.1/19.1% and 2) 26.2/50.5/23.3%. Proportions of E1 homozygote/heterozygote/E2 homozygote for IL-1 beta exon 5 in both groups were 1) 91.6/5/3.3% and 2) 95.15/4.85/0%. Allele I/II/IV/V for IL-1Ra in both groups were 1) 92.5/5.4/1.6/0.4% and 2) 95.1/3.9/1/0%.

CONCLUSIONS

Association of endometriosis with IL-1 beta-511 promoter, IL-1 beta exon 5, and IL-1 receptor antagonist gene polymorphisms doesn't exist. These polymorphisms are not useful markers for prediction of endometriosis susceptibility.

Profile of eicosanoids produced by human saphenous vein endothelial cells and the effect of dietary fatty acids

Human saphenous vein endothelial cells (HSVECs) derived from primary cultures of adult human veins constitute an excellent in vitro model for studying human endothelial metabolism. In this study we report the (14)C-labelled prostanoid profile of HSVECs under resting and stimulated conditions and the effect of the n-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid on them. Results indicate that HSVECs while under resting conditions produce mainly prostaglandin F(2alpha)(PGF(2alpha)). After stimulation with calcium ionophore A23187, the cells were found to synthesise PGI(2), PGE(2)and PGF(2alpha) as major products and thromboxane B(2)and PGD(2)as minor products. Production of (14)C-labelled hydroxyeicosatetraenoic acids was not detected. Eicosapentaenoic acid was found to inhibit basal and stimulated prostanoid production whereas docosahexaenoic acid inhibited basal but strongly increased stimulated prostanoid production. These results may offer the basis for further studies aiming to investigate targets for pharmacological intervention in inflammatory conditions.

Endothelial cell prostacyclin synthesis induced by lymphocytes is independent of the membrane fatty acid composition of both cell types and of E-selectin, VCAM-1 or ICAM-1-mediated adhesion

Prostacyclin (PGI2), the main prostanoid in most vascular tissues regulates haemostasis and vascular tone, as well as the proliferation of smooth muscle cells. We have previously reported that lymphocyte contact with endothelium enhances endothelial cell PGI2 output. Here, we demonstrate the specificity of lymphocytes for switching on this response. Co-incubation of human umbilical vein endothelial cells (HUVEC) in serum-free medium with allogeneic peripheral blood lymphocytes (PBL), at a PBL:HUVEC ratio of 9:1, enhanced the basal (HUVEC alone) PGI2 output by 2.5-fold under static conditions, and was not altered in conditions mimicking shear stress. It occurred without previous activation of either cell type and was dependent upon specific interactions with PBL. Indeed, the PGI2 output induced by the co-incubation with resting neutrophils, non-activated platelets or latex beads was significantly lower than that induced by PBL. Blocking endothelial cell adhesion molecules (ECAM) E-selectin, vascular cell adhesion molecule-1 (VCAM-1) or intracellular adhesion molecule-1(ICAM-1) did not modify the PBL-induced PGI2 output, although 51Cr-labelled PBL adhesion was significantly decreased with anti-ICAM-1 antibody. Changes in the fatty acid composition of membrane phospholipids induced by incubation with eicosapentaenoic (EPA) or docosahexaenoic acids (DHA) resulted in diminished basal PGI2 output and adhesion of 51Cr-labelled PBL, whereas the PBL-stimulated PGI2 output was not modified. This specific cell-cell interaction represents a new stimulus for PGI2 synthesis that does not primarily involve the ECAM pathway, is independent of cell membrane fatty acid composition and shear stress. This switch-on for PGI2 synthesis, which is induced by lymphocytes, might serve as a protection against atherogenesis.

Thrombin-mediated permeability of human microvascular pulmonary endothelial cells is calcium dependent

BACKGROUND

In response to inflammation, endothelial cytoskeleton rearrangement, cell contraction, and intercellular gap formation contribute to a loss of capillary barrier integrity and resultant interstitial edema formation. The intracellular signals controlling these events are thought to be dependent on intracellular calcium concentration ([Ca2+]i). We hypothesized that, in human pulmonary microvascular endothelial cells, a thrombin-induced increase in permeability to albumin would be dependent on Ca2+i and subsequent actin cytoskeleton rearrangements.

METHODS

Human lung microvascular endothelial cells, grown on 0.4 micromol/L pore membranes, were activated with 10 nmol/L human thrombin in Hank's balanced salt solution/0.5% fetal bovine serum. Select cultures were pretreated (45 minutes) with 4 micromol Fura-2/AM to chelate Ca2+i. Permeability was assessed as diffusion of bovine serum albumin/biotin across the monolayer. Similarly treated cells were stained with rhodamine-phalloidin to demonstrate actin cytoskeletal morphology. Separately, cells loaded 2 micromol Fura-2/AM were assessed at OD340/380nm after thrombin exposure to detect free Ca2+i.

RESULTS

Intracellular Ca2+ levels increased 15-fold (2 seconds) and fell to baseline (10 minutes) after thrombin. Permeability increased 10-fold (30 minutes), and a shift from cortical to actin stress fiber morphology was observed. Chelation of Ca2+i diminished permeability to baseline and reduced the percentage of cells exhibiting stress fiber formation.

CONCLUSION

Thrombin stimulates pulmonary capillary leak by affecting the barrier function of activated pulmonary endothelial cells. These data demonstrate a thrombin-stimulated increase in monolayer permeability, and cytoskeletal F-actin stress fibers were, in part, regulated by endothelial Ca2+i. This early, transient rise in Ca2+i likely activates downstream pathways that more directly affect the intracellular endothelial structural changes that control vascular integrity.

Circulating interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and soluble ICAM-1 in patients with chronic stable angina and myocardial infarction

The changes in serum concentrations of cytokines such as interleukin-1 (IL-1) beta, interleukin-6 (IL-6), tumor necrosis factor (TNF) alpha and a soluble-intercellular adhesion molecule (sICAM-1) has been investigated in patients with stable angina and acute myocardial infarction. Thirty-four patients with stable angina (SA), 15 with acute myocardial infarction (AMI), and 20 subjects in the control (C) group were included in the study. The mean serum concentrations of sICAM-1, IL-1-beta, IL-6, and TNF-alpha differed significantly among the three groups. Serum concentrations of IL-1 beta, sICAM-1, and TNF-alpha were comparable in the AMI and SA groups and higher than those found in the C group (p < 0.001). The serum concentration of IL-6 was more than twice as high in the AMI group as compared to the other two groups (p < 0.001). The mean serum concentrations of IL-1 beta, TNF-alpha, and IL-6 were comparable in the AMI and SA groups and higher than in the C group.

Retinal expression, regulation, and functional bioactivity of prostacyclin-stimulating factor

Prostacyclin-stimulating factor (PSF) acts on vascular endothelial cells to stimulate the synthesis of the vasodilatory molecule prostacyclin (PGI2). We have examined the expression, regulation, and hemodynamic bioactivity of PSF both in whole retina and in cultured cells derived from this tissue. PSF was expressed in all retinal cell types examined in vitro, but immunohistochemical analysis revealed PSF mainly associated with retinal vessels. PSF expression was constitutive in retinal pericytes (RPCs) but could be modulated in bovine retinal capillary endothelial cells (RECs) by cell confluency, hypoxia, serum starvation, high glucose concentrations, or inversely by soluble factors present in early vs. late retinopathy, such as TGF-beta, VEGF, or bFGF. In addition, RPC-conditioned media dramatically increased REC PGI2 production, a response inhibited by blocking PSF with a specific antisense oligodeoxynucleotide (ODN). In vivo, PGI2 increased retinal blood flow (RBF) in control and diabetic animals. Furthermore, the early drop in RBF during the initial weeks after inducing diabetes in rats, as well as the later increase in RBF, both correlated with levels of retinal PSF. RBF also responded to treatment with RPC-conditioned media, and this effect could be partially blocked using the antisense PSF ODN. We conclude that PSF expressed by ocular cells can induce PGI2, retinal vascular dilation, and increased retinal blood flow, and that alterations in retinal PSF expression may explain the biphasic changes in RBF observed in diabetes.

Inhibitor of tumor necrosis factor-alpha production in lipopolysaccharide-stimulated RAW264.7 cells from Amorpha fruticosa

Certain flavonoids were reported to show an immunoregulatory activity against lymphocyte proliferation and cytokine production. In the course of a search for tumor necrosis factor (TNF)-alpha inhibitory compounds from natural plants, we also isolated a prenylfavanone type of flavonoid, amoradicin, from the extract of Amorpha fruticosa by activity-guided fractionation. This compound significantly inhibited TNF-alpha production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells with an IC(50) value of 28.5 microM. The activity was comparable or higher than those of standard flavonoid compounds, genistein and silybin with IC(50) of 24.9 and 140.3 microM, respectively.

Eudesmin inhibits tumor necrosis factor-alpha production and T cell proliferation

Possible antiinflammatory effects of eudesmin were examined by assessing the effects on tumor necrosis factor (TNF)-alpha production and lymphocyte proliferation as well as cytotoxicity against murine and human macrophages. The compound significantly inhibited TNF-alpha production by lipopolysaccharide (LPS)-stimulated murine macrophage RAW264.7 without displaying cytotoxicity suggesting that eudesmin may inhibit TNF-alpha production without any interference of normal cell function. It also significantly attenuated T cell proliferation stimulated by concanavalin A (Con A) in a dose-dependent manner.

Interleukin-1 alpha induced cyclooxygenase-2 expression in bone-derived endothelial cells

Histological studies have suggested that vascular endothelial cells in bone are members of a complex network that regulates bone development and remodeling by producing soluble factors or by mediating cell-cell adhesion. To clarify the role of bone-derived endothelial cell lines (BDECs) in bone remodeling, we established several clones of BDECs from the femurs of BALB/c mice after transformation with the SV40 virus. Then we examined the response of these clones to interleukin-1alpha (IL-1alpha). IL-1alpha is known to induce bone resorption in part by increasing the expression of cyclooxygenase-2 (COX-2) that is associated with the production of PGE2 in osteoblast-lineage cells. Treating the primary and established BDECs with IL-1alpha induced COX-2 mRNA expression. A transcriptional activation assay revealed that the treatment with IL-1alpha increased COX-2 promoter activity in a dose-dependent manner, and IL-1alpha promoted COX-2 protein expression in BDECs. Treatment with IL-1alpha promoted PGE2 production from BDECs in a dose-dependent manner. These results indicate that IL-1alpha stimulates PGE2 synthesis largely by inducing BDECs to express COX-2. Because PGE2 stimulates bone resorption, these vascular endothelial cells, as well as osteoblast cells, play important roles in bone remodeling.

The role of adhesion molecules in atherosclerosis

The progression of atherosclerosis is currently believed to involve the interaction of monocytes with the vascular endothelium. Within the last decade, the cell-surface proteins thought to control these interactions have been investigated. This review seeks to describe the nature of these interactions through what are known as adhesion molecules and their role in atherogenesis. It begins with the stages of atherogenesis from the movement of the monocyte to the endothelium, followed by the migration of smooth muscle cells from the media to the intima, and subsequently to the later stages of fibrofatty plaque formation and potential complications due to thrombosis and/or plaque fissure and embolism. The different structural classifications of the adhesion molecules, such as integrins, cadherins, selectins, and members of the immunoglobulin gene superfamily, are outlined, and interaction of binding domains are highlighted. The vascular endothelium and the basic role of adhesion molecules in dysfunction are considered. Discussion of the role of adhesion molecules in atherogenesis focuses on interactions of the endothelium, monocytes, and leukocytes, as well as the influences of cytokines, oxidized low-density lipoproteins, and genetic determinants. Finally, epidemiological risk factors associated with atherosclerosis such as hypertension and dyslipidemia are considered in light of their effects on adhesion molecule expression.

Rate of vasoconstrictor prostanoids released by endothelial cells depends on cyclooxygenase-2 expression and prostaglandin I synthase activity

This study was undertaken to investigate the enzymatic regulation of the biosynthesis of vasoconstrictor prostanoids by resting and interleukin (IL)-1(beta)stimulated human umbilical vein endothelial cells (HUVECs). Biosynthesis of eicosanoids in response to IL-1beta, exogenous labeled arachidonic acid (AA), or histamine, as well as their spontaneous release, was evaluated by means of HPLC and RIA. HUVECs exposed to IL-1beta produced prostaglandin (PG) I2 for no longer than 30 seconds after the substrate was added irrespective of the cyclooxygenase (COX) activity, whereas the time course of PGE2 and PGD2 formation was parallel to the COX activity. The ratio of PGE2 to PGD2 produced by HUVECs was similar to that obtained by purified COX-1 and COX-2. Production of PGF2alpha from exogenous AA was limited and similar in both resting and IL-1beta-treated cells. PGF2alpha was the main prostanoid released into the medium during exposure to IL-1beta, whereas when HUVECs treated with IL-1beta were stimulated with histamine or exogenous AA, PGE2 was released in a higher quantity than PGF2alpha. PGF2alpha released into the medium during treatment with IL-1beta and the biosynthesis of PGE2 and PGD2 in response to exogenous AA or histamine increased with COX-2 expression, whereas this did not occur in the case of PGI2. We observed that PGI synthase (PGIS) mRNA levels were not modified by the exposure to IL-1beta, but the enzyme was partially inactivated. When SnCl2 was added to the incubation medium, the transformation of exogenous AA-derived PGH2 into PGE2 and PGD2 was totally diverted toward PGF2alpha. Overall, these results support the conclusions that PGE2 and PGD2 (and also probably PGF2alpha) were nonenzymatically derived from PGH2 in HUVECs. The concept that a high ratio of PGH2 was released by the IL-1beta-treated HUVECs and isomerized outside the cell into PGE2 and PGD2 was supported by the biosynthesis of thromboxane B2 by COX-inactivated platelets, indicating the uptake by platelets of HUVEC-derived PGH2. The IL-1beta-induced increase in the release of PGH2 by HUVECs was suppressed by the COX-2-selective inhibitor SC-58125 and correlated with both COX-2 expression and PGIS inactivation. An approach to the mechanism of inactivation of PGIS by the exposure to IL-1beta was performed by using labeled endoperoxides as substrate. The involvement of HO. in the PGIS inactivation was supported by the fact that deferoxamine, pyrrolidinedithiocarbamate, DMSO, mannitol, and captopril antagonized the effect of IL-1beta on PGIS to different degrees. The NO synthase inhibitor NG-monomethyl-L-arginine also antagonized the PGIS inhibitory effect of IL-1beta, indicating that NO. was also involved. NO. reacts with O2-. to form peroxynitrite, which has been reported to inactivate PGIS. Homolytic fission of the O-O bond of peroxynitrite yields NO2. and HO.. The fact that 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), which reacts with NO. to form NO2., dramatically potentiated the IL-1beta effect suggests that NO2. could be a species implicated in the inactivation of PGIS. Cooperation of HO. was supported by the fact that DMSO partially antagonized the effect of carboxy-PTIO. Although our results on the exact mechanism of the inactivation of PGIS caused by IL-1beta were not conclusive, they strongly suggest that both NO. and HO. were involved.

Transcription factor decoy for nuclear factor-kappaB inhibits tumor necrosis factor-alpha-induced expression of interleukin-6 and intracellular adhesion molecule-1 in endothelial cells

BACKGROUND

Several cytokines and adhesion molecules released from endothelium play an important role in inflammation, immune responses, and probably atherogenesis.

OBJECTIVE

To determine whether the transcription factor nuclear factor-kappaB mediated expression of these genes involved in the inflammatory response of endothelial cells to tumor necrosis factor-alpha, by using transcription factor decoy oligodeoxynucleotides.

DESIGN AND METHODS

We first transfected fluorescein isothiocyanate (FITC)-labeled double-stranded oligodeoxynucleotides into endothelial cells by a cationic liposome-mediated method of gene transfer. We then confirmed that the decoy oligodeoxynucleotides could block binding of nuclear factor-kappaB to its specific cis element effectively. In addition, we transfected the reporter gene chloramphenicol acetyltransferase driven by three repeated nuclear factor-kappaB binding sequences in the promoter and enhancer region.

RESULTS

FITC-labeled oligodeoxynucleotides were detected in the nuclei of approximately 70% of the total cells. Tumor necrosis factor--stimulated expression of chloramphenicol acetyltransferase was partially inhibited by transfection of nuclear factor-kappaB decoy oligodeoxynucleotides, but not by transfection of scrambled oligodeoxynucleotides. Also nuclear factor-kappaB decoy oligodeoxynucleotides but not scrambled oligodeoxynucleotides inhibited tumor necrosis factor-induced expression of interleukin-6 and intracellular adhesion molecule-1 both at the messenger RNA and at protein level (assessed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay).

CONCLUSION

Our results demonstrate that nuclear factor-kappaB decoy oligodeoxynucleotides transfected by cationic liposome method inhibited tumor necrosis factor--induced expression of interleukin-6 and intracellular adhesion molecule-1 in endothelial cells.

Regulation of inhibitory pathways of the interleukin-1 system

The IL-1 system includes two agonists, converting enzymes, antagonists, and two receptors (R). New elements and functions in the system will be discussed, including (a) cloning of a new isoform of the receptor antagonist; (b) further analysis of the type II IL-1-binding molecule as a decoy R. The modulation of IL-1R by chemotactic signals was recently investigated. It was found that chemoattractants cause rapid release of the type II decoy R from myelomonocytic cells with a t1/2 of 30 sec. Induction of decoy R release represents an early event in the multistep process of recruitment. It may serve to block the systemic action of IL-1 leaking from sites of inflammation, while preserving responsiveness in situ. We recently cloned the first long pentraxin, PTX3 (human and mouse, cDNA and genomic) as an IL-1-inducible gene. The structural and functional features of this molecule as well as initial evidence of involvement in human pathology will be discussed.

Inhibitory effect of lignans from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor-alpha production in lipopolysaccharide-stimulated RAW264.7 cells

The inhibitory effect of 10 lignan constituents isolated from the rhizomes of Coptis japonica var. dissecta on tumor necrosis factor (TNF)-alpha production in lipopolysaccharide (LPS)-stimulated macrophage cell line (RAW264.7 cells) has been studied. Among them, pinoresinol, woorenoside-V and lariciresinol glycoside showed significant inhibitory activities in the range from 37% to 55% at the concentration of 25 micrograms/ml. The results are first report that the lignans isolated from Coptis japonica inhibit TNF-alpha production, and suggest that the lignan components may partly participate in antiinflammatory and antiallergic effect of Coptis japonica through the inhibition of TNF-alpha production.

Interleukin-4 inhibits secretion of interleukin-1beta in the response of human cells to mycobacterial heat shock proteins

Cellular activation induced by Mycobacterium bovis bacillus Calmette-Guérin (BCG) and heat shock proteins (HSP) leads to the production of proinflammatory cytokines such as interleukin-1beta (IL-1beta) and IL-6. In this study, we found that IL-4 significantly suppressed IL-1beta secretion induced by BCG and the 70- and 65-kDa HSP. When exogenous recombinant human IL-4 was added to human mononuclear cells, a dose- and time-related inhibition of the 70-kDa HSP- and BCG-induced IL-1beta secretion was observed. IL-1beta secretion was maximally inhibited at 24 h of culture, and this inhibitory effect was sustained at a later time point of culture (120 h). In addition, IL-2, another T-cell-derived cytokine acting on monocytes, had no effect on IL-1beta secretion induced by either BCG or the 70-kDa HSP, indicating that in these experiments not all cytokines could immunoregulate IL-1beta secretion. This inhibitory effect was not due to a cytotoxic effect of IL-4, since the viabilities of human mononuclear cells were comparable in the presence and absence of IL-4. IL-4 was also able to inhibit the secretion of IL-1beta by mycobacterium-stimulated cells from three rheumatoid arthritis patients. This inhibitory effect of IL-4 was reversed with a blocking anti-IL-4 antibody. Finally, IL-4 inhibited IL-6 secretion by mycobacterium-activated human cells. These results suggest that IL-4 may be important in the regulation of the immune response to mycobacterial antigens.

Interleukin-1 in ischemia-reperfusion acute lung injury

Interleukin-1 (IL-1) is a proinflammatory cytokine produced by blood-borne and resident inflammatory lung tissue involved in the thrombotic occlusion of the pulmonary microcirculation and the increase of the vascular permeability following a wide variety of injuries and sepsis. The locally accentuated, organ-related activation of this cytokine seems to be responsible for the development of acute lung injury. The present study was conducted to determine if IL-1beta was produced in an ischemia-reperfusion (I/R) rat model subjected to lung injury. We measured sequential perfusate levels of IL-1beta by ELISA and we measured IL-1 gene expression in the rat lung tissue by a reverse-transcriptase polymerase chain reaction method. Little IL-1beta gene expression was observed in normal rat lung tissue. Perfusate IL-1beta slightly increased 2 h after induced ischemia and 3 h after reperfusion. IL-1beta gene expression rapidly increased as early as 30 min after ischemia and continued to increase for up to 120 min. IL-1beta gene expression was dramatically upregulated during reperfusion after cessation of ischemia, reached a peak at 1 h, and then gradually decreased (2 to 3 h) to near baseline levels. During ischemia, the increased IL-1 gene expression was not significantly different between the ventral and dorsal sites of the lung. However, IL-1 gene expression markedly increased on the dorsal part (the dependent site for a rat in a supine position) after reperfusion. From these results, it appears that IL-1 may have an important role in I/R lung injury.

Increased serum levels of interleukin-1beta in the systemic circulation of patients with essential hypertension: additional risk factor for atherogenesis in hypertensive patients?

The dysfunction of the immune system has been implicated in the cause of essential hypertension (EH). On the other hand, interleukin- 1beta (IL-1beta) has strongly been involved in the pathogenesis of atheromatosis, whereas our preliminary experiments in serum samples from hypertensive patients before any drug therapy have shown the presence of high concentrations of IL-1beta and the absence of interleukin-2 (IL-2). The aim of this study was first to confirm our preliminary findings and second to investigate the possible interrelation(s) among the parameters studied, particularly between the immunologic markers and the blood pressure or the lipid parameters, because so far there are no data regarding the possible participation of IL-1beta in the cascade phenomena presented during the process of EH such as atherogenesis. Serum samples from 28 consecutive unselected patients with EH before any drug administration or after discontinuation of the antihypertensive therapy for at least 4 weeks, 31 normotensive patients with familial hypercholesterolemia (FH, disease control group), and 35 healthy individuals In a control group matched for age and sex were investigated for the presence of IL-1beta (commercial enzyme immunoassay), soluble IL-2 receptors (slL-2Rs, sandwich enzyme-linked immunosorbent assay set up in our laboratory), and some of the acute phase proteins by nephelometry. In addition, total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoproteins A1 and B, and lipoprotein (a) were determined by standard methods. The data were analyzed by unpaired t test, Mann Whitney-U, chi-squared analysis after Yate's correction, analysis of variance, or Kruskal-Wallis where applicable. Correlation coefficient was calculated by simple regression analysis (r) or nonparametric Spearman correlation coefficient (rs). We found that (1) none of the patients had increased concentrations of sIL-2Rs, and (2) the IL-1beta levels significantly differed in the three groups (p = 0.0001). In more detail, the concentrations of IL-1beta were significantly higher in patients with EH compared with those in patients with FH (p < 0.0005) and the healthy control group (p = 0.0001). By contrast, the IL-1beta concentrations did not differ between patients with FH and the healthy control group. (3) Sixteen (57.1%) patients with EH and only 6 (19.4%) patients with FH (p < 0.01) had increased levels of IL-1beta, and (4) the IL-1beta was not correlated with the acute phase reactants or the lipid parameters in the groups studied. However, the group of patients with EH and increased IL-1beta levels had significantly higher mean concentrations of triglycerides (p < 0.05) and significantly lower mean concentrations of high-density lipoprotein cholesterol (p < 0.05) than those who had IL-1beta levels lower than the cutoff point. (5) The IL-1beta concentrations were positively though slightly correlated with the mean blood pressure only in the group of patients with EH (r = 0.38, p < 0.05). This study demonstrated the presence of high concentrations of IL-1beta and the absence of indicators of cellular immune activation in the systemic circulation of patients with EH, suggesting that this cytokine may be involved in the pathogenesis of EH. In addition, this study showed that the high levels of IL-1beta were associated with lipid indicators of atheromatosis only in the group of patients with EH. More studies are required in an attempt to address whether IL-1beta could have a pathogenetic importance in EH. Taking into account these findings, however, it can be suggested that the presence of high IL-1beta levels may be an additional and perhaps independent risk factor for atheromatosis in patients with EH.

Down-regulation of cyclooxygenase-2 (COX-2) by interleukin-1 receptor antagonist in human monocytes

Cyclooxygenase (COX) is the key rate-limiting enzyme in the synthesis of prostanoids from arachidonic acid. Two isoforms of COX have been described in mammalian cells, referred to as cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). COX-1 is a constitutively expressed enzyme; COX-2 is an inducible enzyme that appears to be expressed in inflamed tissue and following exposure to growth factors or cytokines, such as interleukin-1 (IL-1). The aim of the present study was to test if the antagonism on the binding of IL-1 to its cell-surface receptor by human recombinant IL-1 receptor antagonist (hrIL-1ra) may control the COX mRNA expression and prostaglandin E2 (PGE2) production by human monocyte cultures. Northern blot studies showed that hrIL-ra (500 ng/ml) had a strong inhibitory effect on inducible COX activity. The effect was evident after 6 hr incubation (2.7-fold decrease of mRNA COX-2 transcripts); and about a threefold decrease at 24hr incubation. A non-significant effect was observed with COX-1 transcripts. Induced PGE2 production by monocyte cultures treated with lipopolysaccharide (LPS) or interleukin-1 beta (IL-1 beta) was strongly inhibited in the presence of hrIL-1ra (500 ng/ml). In addition, a significant inhibition of COX-2 protein expression, as evaluated by Western blotting, was also observed. These data suggest that hrIL-1ra may be the key mediator in the down-regulation of the COX-2 inducible pathway.