Polymorphonuclear leukocytes enhance release of growth factors by cultured endothelial cells

Smoking and gingivitis: focus on inducible nitric oxide synthase, nitric oxide and basic fibroblast growth factor

BACKGROUND

Periodontal disease pathogenesis has been associated with smoking. Gingivitis is a mild and reversible form of periodontal disease and it tends to progress to periodontitis only in susceptible individuals. In the present study, we aimed to examine the impact of smoking on host responses in gingivitis and to evaluate and compare the inducible nitric oxide synthase (iNOS) activity in gingival tissue and NO and basic fibroblast growth factor (bFGF) levels in the gingival crevicular fluid of patients with gingivitis and healthy individuals.

MATERIAL AND METHODS

Forty-one participants were assigned to the gingivitis-smoker (n = 13), gingivitis (n = 13), healthy-smoker (n = 7) and healthy groups (n = 8). Clinical indices were recorded; gingival biopsy and gingival crevicular fluid samples were obtained from papillary regions. iNOS expression was evaluated by immunohistochemical staining. The immunoreactive cells were semiquantitatively assessed. For the quantitative determination of nitrite and nitrate in gingival crevicular fluid, the NO assay kit was used. The amount of bFGF in gingival crevicular fluid was determined by enzyme-linked immunosorbent assay.

RESULTS

The gingivitis-smoker group demonstrated a stronger iNOS expression than the non-smoker gingivitis group. iNOS expression intensity was lower in the non-smoker healthy group compared to that in healthy-smokers. No significant gingival crevicular fluid NO and bFGF level changes were observed between groups. Among patients with gingivitis, a positive correlation was detected between gingival crevicular fluid NO and bFGF levels (r = 0.806, p = 0.001).

CONCLUSIONS

Our data suggest that smoking has significant effects on iNOS expression but not on gingival crevicular fluid NO or bFGF levels in healthy and patients with gingivitis. However, our results suggest that bFGF might be involved in the regulation of NO production via iNOS.

Fluoxetine enhances cutaneous wound healing in chronically stressed Wistar rats

OBJECTIVES

To evaluate the histologic and clinical effects of fluoxetine administration on wound healing in chronically stressed and nonstressed Wistar rats.

STUDY DESIGN

Full-thickness incisional wounds were created on the lower back of 72 female Wistar rats. Animals were divided into 2 stress and nonstress groups according to application of stress regimen and 3 subdivisions based on placebo, acute, or chronic administration of fluoxetine. Wound length, width, and linear healing rate based on wound area were measured for 2 weeks postwounding. Biopsies of 3 rats from each group were taken at days 1, 4, 7, and 14 to perform histomorphometric measurements by light microscopy. Analysis of covariance and analysis of variance were used to analyze wound length and other variables, respectively.

RESULTS

Fluoxetine treatment significantly reduced mean wound length and healing period (P<.01). Although stress decreased the linear healing rate by 48%, fluoxetine treatment increased it by 68% and 31% in stressed and nonstressed rats, respectively. Stress significantly diminished infiltration of neutrophils and monocytes (P<.01), disrupted spatial organization of fibroblasts, and delayed neovascularization. Fluoxetine precluded these effects successfully.

CONCLUSION

Fluoxetine significantly improves healing of cutaneous wounds in stressed and, to a lesser extent, in nonstressed animals.

The alanine/threonine polymorphism of the alpha-1-antichymotrypsin (SERPINA3) gene and ruptured intracranial aneurysms in the Japanese population

BACKGROUND

Serine protease inhibitor member 3 of clade A (SERPINA3), also known as alpha-1-antichymotrypsin, inhibits the activity of cathepsin G. The release of neutrophil cathepsin G (proteolytic enzyme) can destroy the vascular matrix through degradation, platelet aggregation and coagulation disorders. In a previous report there was evidence that an alanine/threonine polymorphism was associated with the risk factor for aneurysmal subarachnoid hemorrhage (SAH) in a Polish population. We performed this study to determine whether this A15T polymorphism shows the same association in a Japanese population.

METHODS

A total of 437 patients with an aneurysmal SAH and 405 control cases of Japanese origin were genotyped for the A15T polymorphism and 2 further intronic single nucleotide polymorphisms by using polymerase chain reaction and direct sequencing.

RESULTS

In the patients with intracranial aneurysms the SERPINA3 A15T allele and genotype distribution did not differ significantly from the controls.

CONCLUSION

In the Japanese population the A15T polymorphism of the SERPINA3 gene is not associated with aneurysmal SAH.

Effect of Vascular Endothelial Growth Factor on Fibroblasts from External Auditory Canal Cholesteatoma

BACKGROUND

EACC is a disease of the external auditory canal resulting in destruction of adjacent tissue. However, the role of the surrounding mesenchymal fibroblasts of the perimatrix still remains unclear. In this study we treat isolated fibroblasts of EACC with VEGF and determine FGF-2 levels. We also treat the fibroblast cultures with FGF-2 and measured VEGF levels.

METHODS

All EACC cell cultures were obtained from five patients undergoing surgery and used at passage 3. After 1-4 days incubation with 50 ng/mL FGF-2, and 1-8 days incubation with 50 pg/mL VEGF incubation, the expression of the FGF-2 and VEGF protein in the supernatants of the HGF/SF-treated and -untreated culture cell lines was analyzed, respectively.

RESULTS

After 8 days of incubation with 50 ng/mL VEGF, the levels of FGF-2 decreased. However, after 4 days of incubation with FGF-2 the VEGF levels increased significantly in treated tissue culture (p <0.05) in comparison to untreated EACC fibroblasts. The total protein concentration showed no significant difference in both cultures (p >0.05).

CONCLUSIONS

In summary, exogenous FGF-2 increased fibroblast expression of VEGF, which is a major autocrine mediator of FGF-2-induced angiogenesis and proliferation. However, incubation with VEGF resulted in decrease of FGF-2 levels. Regarding the slow growth of the fibroblasts, they may not be as likely to exhibit a reactive or invasive phenotype as seen in middle ear cholesteatoma fibroblasts.

Resveratrol: Preventing properties against vascular alterations and ageing

Cardiovascular diseases are the leading cause of death in developed countries where the common pathological substrate underlying this process is atherosclerosis. Several new concepts have emerged in relation to mechanisms that contribute to the regulation of the vascular diseases and associated inflammatory effects. Recently, potential antioxidants (vitamin E, polyphenols) have received much attention as potential anti-atherosclerotic agents. Among the polyphenols with health benefic properties, resveratrol, a phytoalexin of grape, seem to be a good candidate protecting the vascular walls from oxidation, inflammation, platelet aggregation, and thrombus formation. In this review, we focus on the mechanism of resveratrol cardiovascular benefic effects. We analyze, in relation with the different steps of atherosclerotic process, the resveratrol properties at multiple levels, such as cellular signaling, enzymatic pathways, apoptosis, and gene expression. We show and discuss the relationship with reactive oxygen species, regulation of pro-inflammatory genes including cycloxygenases and cytokines in molecular inflammatory and aging processes, and how the regulation of these activites by resveratrol can lead to a prevention of vascular diseases.

Reduction of ICAM-1 and LFA-1-positive leukocytes in the perivascular space of arteries under mycophenolate mofetil therapy reduces rat heart transplant vasculopathy

BACKGROUND

The interaction of lymphocyte function-associated antigen-1 (LFA-1)-positive host leukocytes with intercellular adhesion molecule-1 (ICAM-1) on graft endothelium may play a key role in allograft recognition, triggering the development of transplant vasculopathy (TVP). We investigated the correlation between TVP and ICAM-1 expression and accumulation of LFA-1-positive leukocytes in the perivascular space (PVS) of arteries under different immunosuppressive drugs.

METHODS

After cardiac transplantation (Lewis to Fisher) animals were randomized 4 groups: cyclosporine (CsA), 3 mg/kg/day (n=74); mycophenolate mofetil (MMF), 40 mg/kg/day (n=96); FK 506, 0.3 mg/kg/day (n=96); and control, no therapy (n=74). Three or 4 animals from each group were harvested at intervals of 1 to 4 days within the study period of 60 days. Using immunohistochemistry, LFA-1-positive leukocytes were analyzed in intra- and epicardial arteries. ICAM-1 expression was scored histologically. TVP was assessed by digitizing morphometry and expressed as mean vascular occlusion.

RESULTS

Accumulation of LFA-1-positive leukocytes in the PVS of arteries and the myocardium correlated with expression of ICAM-1 on graft endothelium. The severity of TVP in arteries correlated with the accumulation of LFA-1-positive leukocytes in PVS. All immunosuppressive drugs significantly reduced ICAM-1 expression, LFA-1 accumulation and extent of TVP, compared with controls. In MMF-treated animals, we also found a significant reduction of ICAM-1 expression, LFA-1 accumulation and extent of TVP compared with the groups treated with CsA and FK 506 (p <0.005).

CONCLUSION

These data support an essential role of LFA-1/ICAM-1 interaction in the genesis of TVP that may be abrogated, especially by the use of MMF.

Expression of protease-activated receptors (PARs) in OLN-93 oligodendroglial cells and mechanism of PAR-1-induced calcium signaling

Protease-activated receptors (PARs) are a group of four members of the superfamily of G protein-coupled receptors that transduce cell signaling by proteolytic activity of extracellular serine proteases, such as thrombin. Possible expression and functions of PARs in oligodendrocytes, the myelin forming cells of the CNS, are still unclear. Here, the oligodendrocyte cell line OLN-93 was used to investigate the signaling of PARs. By reverse transcription-polymerase chain reaction (RT-PCR), immunostaining and Ca(2+) imaging studies, we demonstrate that OLN-93 cells functionally express PAR-1. PAR-3 seems to be expressed without apparent activity, and PAR-2 and PAR-4 cannot be detected. Short-term stimulation of the OLN-93 cells with PAR-1 agonists, such as thrombin, trypsin and PAR-1 activating peptide, dose-dependently induced a transient rise of [Ca(2+)](i). Concentration-effect curves display a sigmoidal concentration dependence. Elevation of [Ca(2+)](i) induced by PAR-1 mainly resulted from Ca(2+) release from intracellular stores. Studies on the effects of pertussis toxin (PTX), phospholipase C antagonist and 2-APB, showed that in OLN-93 cells (i). the calcium signaling cascade from PAR-1 was mediated through PTX-insensitive G proteins, (ii). activation of phospholipase C and liberation of InsP(3) were events upstream of the Ca(2+) release from the stores. In addition, the present study analyzed PAR-1 desensitization caused by exposure to thrombin, trypsin, and PAR-1 activating peptide, elucidated the influence of the protease cathepsin G on PAR-1 activation, and also characterized PAR-1 desensitization. This is the first study, which shows that OLN-93 oligodendrocytes functionally express PAR-1, and identifies the receptor coupling to mobilization of intracellular calcium. Moreover, the expression of PAR-1 was demonstrated by RT-PCR in primary oligodendrocytes from rat brain.

Mycophenolate mofetil significantly reduces leukocyte graft infiltration after heterotopic cardiac transplantation in a rat model: comparative study with cyclosporine and FK 506

BACKGROUND

The purpose of the study was to evaluate the effects of cyclosporine (CsA), FK 506 and mycophenolate mofetil (MMF) on graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) after cardiac transplantation in rats.

METHODS

Three hundred forty animals were transplanted and randomly divided into 4 groups: CsA, 3 mg/kg/d (n = 74); MMF, 40 mg/kg/d (n = 96); FK 506, 0.3 mg/kg/d (n = 96); and a control group receiving no immunosuppressive therapy (n = 74). Three or 4 animals from each group were killed at intervals of 1 to 4 days up to Day 60. Immunohistochemistry was performed using monoclonal antibodies (MAb) against CD4, CD8, CD11a and CD18. Positively stained cells were analyzed in the perivascular space (PVS) of intra- and epicardial arteries. Statistical analysis was performed using area-under-the-curve assessment with an extended t-test.

RESULTS

CsA and FK 506 reduced the presence graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) in the PVS of intra- and epicardial arteries when compared with control animals. MMF therapy resulted in a further significant reduction in infiltrating leukocytes when compared with the 2 calcineurin inhibitors. MMF had a faster onset of action than the calcineurin inhibitors. CsA and FK 506 required 12 to 20 additional days to achieve the reducing effect of graft infiltration seen in MMF-treated animals.

CONCLUSION

MMF possesses potent infiltration-blocking properties and its application leads to a greater reduction of cellular infiltration in the course of transplant rejection when compared with calcineurin inhibitors.

Endothelium-dependent relaxation induced by cathepsin G in porcine pulmonary arteries

Serine proteinases elicit profound cellular effects in various tissues mediated by activation of proteinase-activated receptors (PAR). In the present study, we investigated the vascular effects of cathepsin G, a serine proteinase that is present in the azurophil granules of leukocytes and is known to activate several cells that express PARs. In prostaglandin F2alpha (3 microM)-precontracted rings from porcine pulmonary arteries with intact endothelium, cathepsin G caused concentration-dependent relaxant responses (pEC(50)=9.64+/-0.12). The endothelium-dependent relaxant effect of cathepsin G could also be demonstrated in porcine coronary arteries (pEC(50)=9.23+/-0.07). In pulmonary arteries the cathepsin G-induced relaxation was inhibited after blockade of nitric oxide synthesis by L-NAME (200 microM) and was absent in endothelium-denuded vessels. Bradykinin- and cathepsin G-induced relaxant effects were associated with a 5.7 fold and 2.4 fold increase in the concentration of cyclic GMP, respectively. Compared with thrombin and trypsin, which also produced an endothelium-dependent relaxation in pulmonary arteries, cathepsin G was 2.5 and four times more potent, respectively. Cathepsin G caused only small homologous desensitization. In cathepsin G-challenged vessels, thrombin was still able to elicit a relaxant effect. The effects of cathepsin G were blocked by soybean trypsin inhibitor (IC(50)=0.043 microg ml(-1)), suggesting that proteolytic activity is essential for induction of relaxation. Recombinant acetyl-eglin C proved to be a potent inhibitor (IC(50)=0.14 microg ml(-1)) of the cathepsin G effect, whereas neither indomethacin (3 microM) nor the thrombin inhibitor hirudin (5 ATU ml(-1)) elicited any inhibitory activity. Due to their polyanionic structure defibrotide (IC(50)=0.11 microg ml(-1)), heparin (IC(50)=0.48 microg ml(-1)) and suramin (IC(50)=1.85 microg ml(-1)) diminished significantly the relaxation in response to the basic protein cathepsin G. In conclusion, like thrombin and trypsin, cathepsin G is able to induce endothelium-dependent vascular relaxation. It can be released from activated leukocytes at sites of vascular injury and inflammation and, therefore, sufficiently high concentrations might be reached locally in the vascular space to induce vasodilatation.

Protease activated receptors: theme and variations

The four PAR family members are G protein coupled receptors that are normally activated by proteolytic exposure of an occult tethered ligand. Three of the family members are thrombin receptors. The fourth (PAR2) is not activated by thrombin, but can be activated by other proteases, including trypsin, tryptase and Factor Xa. This review focuses on recent information about the manner in which signaling through these receptors is initiated and terminated, including evidence for inter- as well as intramolecular modes of activation, and continuing efforts to identify additional, biologically-relevant proteases that can activate PAR family members.

Vascular smooth muscle cells preloaded with eicosapentaenoic acid and docosahexaenoic acid fail to respond to serotonin stimulation

Epidemiological, animal and clinical studies indicate that n-3 fatty acids may benefit individuals with known history of cardiovascular disease or at risk of developing it. Though there is indirect evidence to suggest that the beneficial effects of n-3 fatty acids may be because of their ability to inhibit smooth muscle cell (SMC) proliferation, there are no studies that have examined this hypothesis. In this study, the mitogenic effect of serotonin (5HT) and platelet derived growth factor (PDGF), known mitogens for vascular SMC, on aortic SMCs preloaded with eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is examined. 5HT and PDGF could only partially stimulate proliferation of SMC that were preloaded with EPA or DHA as compared to the control cells. gamma-Linolenic acid (LA) and oleic acid (OA) did not block the 5HT or PDGF induced 3[H]thymidine incorporation suggesting that the anti-proliferative effect was specific to n-3 fatty acids only. Further, when EPA and DHA were combined in the ratio they are present in fishoils, there was a synergistic interaction in inhibiting the proliferation of SMC. Further, SMC grown in the presence of EPA or DHA, when stimulated with 5HT, failed to show an increase in 5HT(2) receptor mRNA. One of the potential mechanism by which fish oils may prevent the development of atherosclerosis or restenosis could be inhibition of the mitogen induced SMC proliferation. Combination of EPA with DHA is likely to be more beneficial.

Serotonin fails to induce proliferation of endothelial cells preloaded with eicosapentaenoic acid and docosahexaenoic acid

Diets rich in fish oils are associated with a reduced risk of cardiovascular disease including reduction of atherosclerosis and restenosis. We examined the effect of omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), major components of fish oils, on serotonin (5HT) stimulated vascular endothelial cells proliferation as a possible mechanism for this vascular protective effect. In this study we demonstrate that 5HT, a known mitogen for vascular endothelial cells, failed to stimulate proliferation of endothelial cells pre-incubated with EPA and DHA. This inhibitory effect was specific for omega-3 fatty acids only and not shared by other fatty acids like oleic acid (monounsaturated) or arachidonic acid (polyunsaturated) or palmitic acid (saturated). When endothelial cells were exposed to EPA and DHA in the ratio present in fish oils, EPA and DHA were shown to act synergistically in inhibiting the proliferative effect of 5HT. These results suggests that one of the mechanisms by which fish oils may confer vascular protective effect is by making the endothelial cells less responsive to mitogenic stimuli of growth factors such as 5HT that are released by aggregating platelets at sites of vascular injury. This inhibition of endothelial cell proliferation may account for the clinically observed effects of fish oil in attenuating the progression of atherosclerotic changes or neointimal proliferation following vascular injury.

Effect of trans-resveratrol, a natural polyphenolic compound, on human polymorphonuclear leukocyte function

1. Polymorphonuclear leukocytes (PMN) may contribute to the pathogenesis of acute coronary heart disease (CHD). 2. Epidemiological and laboratory evidence suggests that red wine, by virtue of its polyphenolic constituents, may be more effective than other alcoholic beverages in reducing the risk of CHD mortality. 3 The aim of the present study was to investigate the effects of trans-resveratrol (3,4',5-trihydroxy-trans-stilbene), a polyphenol present in most red wines, on functional and biochemical responses of PMN, upon in vitro activation. 4. trans-Resveratrol exerted a strong inhibitory effect on reactive oxygen species produced by PMN stimulated with 1 microM formyl methionyl leucyl phenylalamine (fMLP) (IC50 1.3+/-0.13 microM, mean+/-s.e.mean), as evaluated by luminol-amplified chemiluminescence. 5. trans-Resveratrol prevented the release of elastase and beta-glucuronidase by PMN stimulated with the receptor agonists fMLP (1 microM, IC50 18.4+/-1.8 and 31+/-1.8 microM), and C5a (0.1 microM, IC50 41.6+/-3.5 and 42+/-8.3 microM), and also inhibited elastase and beta-glucuronidase secretion (IC50 37.7+/-7 and 25.4+/-2.2 microM) and production of 5-lipoxygenase metabolites leukotriene B4 (LTB4), 6-trans-LTB4 and 12-trans-epi-LTB4 (IC50 48+/-7 microM) by PMN stimulated with the calcium ionophore A23187 (5 microM). 6. trans-Resveratrol significantly reduced the expression and activation of the beta2 integrin MAC-1 on PMN surface following stimulation, as revealed by FACS analysis of the binding of an anti-MAC-1 monoclonal antibody (MoAb) and of the CBRM1/5 MoAb, recognizing an activation-dependent epitope on MAC-1. Consistently, PMN homotypic aggregation and formation of mixed cell-conjugates between PMN and thrombin-stimulated fixed platelets in a dynamic system were also prevented by transresveratrol. 7. These results, indicating that trans-resveratrol interferes with the release of inflammatory mediators by activated PMN and down-regulates adhesion-dependent thrombogenic PMN functions, may provide some biological plausibility to the protective effect of red wine consumption against CHD.

Symptoms of chronic bronchitis and the risk of coronary disease

BACKGROUND

Experimental and epidemiological studies show a positive association between coronary disease and various infections in different organs, both viral and bacterial and both acute and chronic. Most attention has been paid to dental infections and infections in the respiratory tract. We have studied how chronic respiratory infection predicts coronary disease.

METHODS

We defined chronic respiratory infection by the occurrence of symptoms of chronic bronchitis. We also analysed whether any association with coronary disease incidence and mortality is independent of the known major cardiovascular risk factors and whether it is similar among persons in different occupations. Our cohort study was a 13-year follow-up of 19,444 randomly selected eastern Finnish men and women born between 1913 and 1947 and examined in either 1972 or 1977.

FINDINGS

During follow-up, there were 1419 first coronary events, either fatal or non-fatal, and 614 coronary deaths. Among men, the age-adjusted and study-year-adjusted risk ratio of long lasting-symptoms of chronic bronchitis (during as much as 3 months in a year) was 1.52 (95% CI 1.33-1.75) for coronary disease and 1.74 (CI 1.43-2.11) for coronary death. Among women the risk ratios were 1.38 (1.07-1.78) and 1.49 (0.98-2.27), respectively. Inclusion of smoking, serum cholesterol, and systolic blood pressure into the models decreased risk ratios to 1.36 (1.17-1.56) and 1.55 (1.26-1.90) in men and to 1.34 (1.04-1.74) and 1.41 (0.92-2.16) in women, respectively. The risk of coronary disease associated with the symptoms of chronic bronchitis was similar among blue-collar and white-collar workers but the association was not found among farmers.

INTERPRETATION

Symptoms of chronic bronchitis predicted the risk of coronary disease independently from the known major cardiovascular risk factors. If the observed association is causal, prevention and improved management of chronic infections may have played a role in the decrease in coronary disease mortality observed in eastern Finland in the past two decades.

Trypsin promotes C6 glioma cell proliferation in serum- and growth factor-free medium

C6 glioma cells could be successively subcultured and maintained in serum- and growth factor-free medium (SF/GFF medium). C6 cell proliferation in SF/GFF medium was positively correlated with the initial cell density at plating. This correlation disappeared when the medium had been renewed early after cell adhesion (3 h after plating), suggesting that C6 cell growth depends on some diffusible factor in the medium before renewal, and that this factor is not secreted from C6 cells in the assay culture but is transferred from the cell suspension. The supernatant of trypsinized C6 cell suspension (SCS), trypsin-EDTA solution for routine cell harvesting use, and modified trypsin of protein sequencing grade all promoted C6 cell proliferation at, appropriate dilutions or concentrations under SF/GFF conditions. The growth promoting effects of SCS and trypsin-EDTA solution were completely inhibited by soybean trypsin inhibitor. These results demonstrate that the serine protease trypsin has a proliferative effect on C6 cells continuously subcultured in SF/GFF medium. In addition, it is suggested that trypsin used for cell dispersion is transferred from cell suspension into the culture, where it promotes C6 cell growth after passage in our SF/GFF subculture system.

Exogenous leukocyte and endogenous elastases can mediate mitogenic activity in pulmonary artery smooth muscle cells by release of extracellular-matrix bound basic fibroblast growth factor

There is increasing evidence that extracellular matrix (ECM)-degrading proteinases contribute to the process of medial hypertrophy and neointimal proliferation in pulmonary vascular diseases. However, little is known about how proteinases, specifically elastases, induce vascular smooth muscle cell (SMC) hyperplasia. Our objective was to determine whether exogenous human leukocyte elastase (HLE), as well as endogenous vascular elastase, could release basic fibroblast growth factor (bFGF), a potent mitogen stored in the ECM surrounding SMCs. Cultured ovine and porcine pulmonary artery SMC were pre-incubated with [125I]-bFGF. After removal of unbound [125I]-bFGF, administration of HLE (0-1.0 microgram /ml, 1 h) resulted in a concentration-dependent accumulation of [125I]-bFGF in the conditioned medium, mirrored by depletion from the ECM. The serine elastase inhibitor elafin blocked this HLE-mediated action. Assessment by Western immunoblotting further demonstrated that HLE evoked the release of ECM-bound endogenous bFGF. When incubated with serum-starved SMC, conditioned medium from HLE-treated cells stimulated [3H]-thymidine incorporation, a feature neutralized by bFGF antibodies. In addition, SMC exposed to serum treated elastin (STE), previously shown to stimulate endogenous vascular elastase, liberated bioavailable bFGF from ECM stores, as determined by autoradiography, Western immunoblotting, and stimulation of DNA synthesis and SMC proliferation. Chondroitin sulfate, an inhibitor of STE-induced elastase activity, attenuated the release of bFGF. Our studies demonstrate that HLE, secreted by inflammatory cells, and endogenous vascular elastase release matrix-bound bFGF, suggesting a mechanism whereby elastases, through degradation of ECM, induce SMC proliferation associated with progressive vascular disease.

Endothelial dysfunction in preeclampsia. Part II: Reducing the adverse consequences of endothelial cell dysfunction in preeclampsia; therapeutic perspectives

Next to low-dose Aspirin there appear to be several new and promising pharmacologie approaches for reducing the adverse consequences of endothelial cell dysfunction in preeclampsia. Among these are selective thromboxane-A2 synthetase and/or thromboxane-A2 receptor antagonists, stable prostacyclin analogues, selective S(erotonin)2-receptor blockers, nitrovasodilators, glycoprotein IIb/IIIa antagonists, hirudin, and ticlopidine. Early-onset preeclampsia appears to be associated with certain disorders that are likely to provoke an arterial thrombotic process by impairing the normal endothelial cell-platelet interactions. Especially heterozygous hyperhomocysteinemia, protein S deficiency and anticardiolipin antibodies appear to be fairly common. The management of these 3 separate disease entities will be discussed.

Proteolysis of the human platelet and endothelial cell thrombin receptor by neutrophil-derived cathepsin G

Cathepsin G is a neutrophil-derived protease that has been shown to inhibit the effects of thrombin on some cells expressing thrombin receptors while acting as an agonist on others. The present studies examine whether cleavage of the thrombin receptor by cathepsin G can account for these diverse effects. When added to cells that normally respond to thrombin, cathepsin G prevented a subsequent cytosolic Ca2+ increase caused by thrombin, but had no effect on responses to the thrombin receptor agonist peptide, SFLLRN. These effects were observed in cells in which cathepsin G had little or no agonist effect (human umbilical vein endothelial cells and HEL cells), as well as in cells in which cathepsin G acted as an agonist (platelets and CHRF-288 cells). Binding studies using monoclonal antibodies with defined epitopes within the first 60 residues of the thrombin receptor N-terminus showed that incubation of platelets and endothelial cells with cathepsin G abolished the binding of all of the antibodies, while thrombin abolished only the binding of antibodies whose epitopes were N-terminal to the known thrombin cleavage site between Arg41 and Ser42. Analysis of peptide proteolytic fragments identified three potential cleavage sites for cathepsin G: Arg41-Ser42, Phe43-Leu44, and Phe55-Trp56. Cleavage at Phe55-Trp56 would account for both the observed loss of all of the antibody binding sites and the inhibition of receptor activation by thrombin. Two approaches were used to determine whether a solitary cleavage at Arg41-Ser42 could result in receptor activation. In the first, HEL cells were exposed to cathepsin G or thrombin in the presence of an antibody whose epitope includes Phe55. The antibody inhibited responses to thrombin, but augmented the response to cathepsin G. In the second, COS-1 cells were transfected with variant thrombin receptors in which Phe55 and Trp56 were mutated to alanine. Transfected wild-type receptors responded to thrombin, but not cathepsin G, while the variant receptors responded to both proteases. These results 1) suggest that the ability of cathepsin G to inhibit responses to thrombin, but not SFLLRN, is due to cleavage of the receptor at Phe55-Trp56, deleting the tethered ligand domain, and 2) show that cathepsin G can activate thrombin receptors, but only if the cleavage site at Phe55-Trp56 is mutated or otherwise protected.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructural characteristics of cellular reaction after experimentally induced lesions in the arterial vessel

Restenosis after angioplasty occurs with an incidence of 20-50% and remains a major drawback. Certain randomized studies suggest that a bigger post-angioplasty lumen predicts a better long-term outcome. Conversely other studies showed a better outcome with limited injury. The present study aimed to investigate the depth of the lesion and relate this to cellular alterations after graded vascular injury.

METHOD

Vessel segments of 30 pigs underwent injury using a directional atherectomy catheter. Vessels were assigned according to the extent of injury to Group 1 (intima lesion) or Group 2 (media injury). 2 hours to 7 days after injury, 68 arteries showing 41 intimal and 27 media lacerations were excised and processed for histology and transmission electron microscopy.

RESULTS

Immediately after injury, thrombus formation was found at the site of the altered segment. A marked, transient infiltration of polymorphonuclear leukocytes (PMN) occurred only if the media was lacerated, starting within the first hours and increasing up until the 12 hours time point. The cellular infiltration was followed by a transformation of contractile myocytes to a synthetic subtype. The ratio of myofilaments to organelles decreased. A pronounced myoproliferative response was found in Group 2 after 7 days (p < 0.01), whereas only moderate tissue hyperplasia was seen in Group 1.

CONCLUSION

The data presented provide evidence that the cellular alteration of injured vessels begins immediately. Subsequent to an initial temporary PMN infiltration, an activation of local myocytes occurs at a very early stage. In particular, a myoproliferative response was found only after deep injury with rupture of the internal elastic lamina.