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| 2. |
- Asplund Persson, Anna, 1966-, et al.
(författare)
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Cross-talk between adenosine and the oxatriazole derivative GEA 3175 in platelets
- 2005
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999 .- 1879-0712. ; 517:3, s. 149-157
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Tidskriftsartikel (refereegranskat)abstract
- We examined the interplay between adenosine and the nitric oxide (NO)-containing oxatriazole derivative GEA 3175 in human platelets. The importance of cyclic guanosine 3′5′-monophosphate (cGMP)-inhibited phosphodiesterases (PDEs) was elucidated by treating the platelets with adenosine combined with either GEA 3175 or the PDE3-inhibitor milrinone. The drug combinations provoked similar cyclic adenosine 3′5′-monophosphate (cAMP) responses. On the contrary, cGMP levels were increased only in GEA 3175-treated platelets. Both drug combinations reduced P-selectin exposure, platelet adhesion and fibrinogen-binding. However, adenosine together with GEA 3175 was more effective in inhibiting platelet aggregation and ATP release. Thrombin-induced rises in cytosolic Ca2+ were suppressed by the two drug combinations. Adenosine administered with GEA 3175 was, however, more effective in reducing Ca2+ influx.In conclusion, the interaction between adenosine and GEA 3175 involves cGMP-mediated inhibition of PDE3. The results also imply that inhibition of Ca2+ influx represent another cGMP-specific mechanism that enhances the effect of adenosine.
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| 3. |
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| 4. |
- Bengtsson, Torbjörn, 1955-, et al.
(författare)
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Role of the actin cytoskeleton during respiratory burst in chemoattractant-stimulated neutrophils
- 2006
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Ingår i: Cell Biology International. - : Wiley. - 1065-6995 .- 1095-8355. ; 30:2, s. 154-163
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to clarify the role of the actin cytoskeleton during chemotactic peptide fMet-Leu-Phe (fMLF)-stimulated respiratory burst in human neutrophil granulocytes. Reactive oxygen species (ROS) was measured as luminol-amplified chemiluminescence (CL) and F-actin content as bodipy phallacidin fluorescence in neutrophils treated with latrunculin B or jasplakinolide, an inhibitor and activator of actin polymerization, respectively. Latrunculin B markedly decreased, whereas jasplakinolide increased, the F-actin content in neutrophils, unstimulated or stimulated with fMLF. Latrunculin B enhanced the fMLF-triggered ROS-production more than tenfold. Jasplakinolide initially inhibited the fMLF-induced CL-response, however, caused a potent second sustained phase (>400% of control). Both actin drugs triggered a substantial CL-response when added 5-25 min after fMLF. This was also valid for chemotactic doses of fMLF, where latrunculin B and jasplakinolide amplified the ROS-production 5-10 times. By using specific signal transduction inhibitors, we found that the NADPH oxidase activation triggered by destabilization of the actin cytoskeleton occurs downstream of phospholipase C and protein kinase C but is mediated by Rho GTPases and tyrosine phosphorylation. In conclusion, rearrangements of the actin cytoskeleton are a prerequisite in connecting ligand/receptor activation, generation of second messengers and assembly of the NADPH oxidase in neutrophil granulocytes. © 2005 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.
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| 5. |
- Bengtsson, Torbjörn, et al.
(författare)
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The periodontal pathogen Porphyromonas gingivalis cleaves apoB-100 and increases the expression of apoM in LDL in whole blood leading to cell proliferation
- 2008
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Ingår i: Journal of Internal Medicine. - : Institutionen för medicin och hälsa. - 0954-6820 .- 1365-2796. ; 263:5, s. 558-571
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Several studies support an association between periodontal disease and atherosclerosis with a crucial role for the pathogen Porphyromonas gingivalis. This study aims to investigate the proteolytic and oxidative activity of P. gingivalis on LDL in a whole blood system by using a proteomic approach and analyze the effects of P. gingivalis-modifed LDL on cell proliferation.Methods: The cellular effects of P. gingivalis in human whole blood were assessed using lumi-aggregometry analyzing reactive oxygen species (ROS) production and aggregation. Blood was incubated for 30 min with P. gingivalis, whereafter LDL was isolated and a proteomic approach was applied to examine protein expression. LDL-oxidation was determined by analyzing the formation of protein carbonyls. The effects of P. gingivalis-modifed LDL on fibroblast proliferation were studied using the MTS-assay.Results: Incubation of whole blood with P. gingivalis caused an extensive aggregation and ROS-production, indicating platelet and leukocyte activation. LDL prepared from the bacteria-exposed blood showed an increased protein oxidation, elevated levels of apoM and formation of two apoB-100 N-terminal fragments. P. gingivalis-modified LDL markedly increased the growth of fibroblasts. Inhibition of gingipain R suppressed the modification of LDL by P. gingivalis.Conclusions: The ability of P. gingivalis to change the protein expression and the proliferative capacity of LDL may represent a crucial event in periodontitis-associated atherosclerosis.
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| 6. |
- Berg, Cecilia, et al.
(författare)
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Platelet-induced growth of human fibroblasts is associated with an increased expression of 5-lipoxygenase.
- 2006
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Ingår i: Thrombosis and haemostasis. - 0340-6245. ; 96:5, s. 652-9
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Tidskriftsartikel (refereegranskat)abstract
- Proliferation of fibroblasts is vital for adequate wound healing but is probably also involved in different hyperproliferative disorders such as atherosclerosis and cancer. The regeneration of tissue usually starts with coagulation, involving release of mitogenic and inflammatory factors from activated platelets. This study focuses on the role of eicosanoids in the proliferative effects of platelets on human fibroblasts. We show that the phospholipase A (2) inhibitor 7,7-dimethyl-5,8-eicosadienoic acid (DMDA), the combined cyclooxygenase (COX) and lipoxygenase (LOX) inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA) and the LOX inhibitor 5,8,11-eicosatriynoic acid (ETI) block the platelet-induced proliferation of serum starved subconfluent human fibroblasts. Anti-proliferative effects were also obtained by specific inhibition of 5-LOX with 5,6-dehydro arachidonic acid (5,6-dAA), whereas the 12-LOX inhibitor cinnamyl-3,4-dihydroxy- a -cyanocinnamate (CDC) did not affect the platelet-stimulated growth of fibroblasts. The expression of 5-LOX was analyzed by reverse-transcriptase-mediated PCR (RT-PCR), Western blotting and HPLC. 5-LOX message and protein was detected in fibroblasts but not in platelets. Incubation with platelets markedly increased, already after one hour, the expression of 5-LOX in the fibroblast culture. The increased 5-LOX activity was associated with an elevated level of the 5-LOX metabolite 5-hydroxyeicosatetraenoic acid (5-HETE) reaching its maximum after 1 - 2 hours of co-incubation of fibroblasts and platelets. The 5-HETE production was reduced by the inhibitors DMDA, ETYA and ETI. In conclusion, this study suggests that platelet-stimulated proliferation of fibroblasts is mediated by an increased 5-LOX activity, which supports recent findings indicating a crucial role for this enzyme in proliferative disorders such as atherosclerosis.
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| 7. |
- Berg, Cecilia, 1976-, et al.
(författare)
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Platelet-induced growth of human fibroblasts is associated with an increased expression of 5-lipoxygenase
- 2006
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 96:5, s. 652-659
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Tidskriftsartikel (refereegranskat)abstract
- Proliferation of fibroblasts is vital for adequate wound healing but is probably also involved in different hyperproliferative disorders such as atherosclerosis and cancer. The regeneration of tissue usually starts with coagulation, involving release of mitogenic and inflammatory factors from activated platelets. This study focuses on the role of eicosanoids in the proliferative effects of platelets on human fibroblasts. We show that the phospholipase A2 inhibitor 7,7-dimethyl-5,8-eicosadienoic acid (DMDA), the combined cyclooxygenase (COX) and lipoxygenase (LOX) inhibitor 5,8,11,14-eicosatetraynoic acid (ETYA) and the LOX inhibitor 5,8,11-eicosatriynoic acid (ETI) block the platelet-induced proliferation of serum starved subconfluent human fibroblasts. Anti-proliferative effects were also obtained by specific inhibition of 5-LOX with 5,6-dehydro arachidonic acid (5,6-dAA), whereas the 12-LOX inhibitor cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) did not affect the platelet-stimulated growth of fibroblasts. The expression of 5-LOX was analyzed by reverse-transcriptase-mediated PCR (RT-PCR), Western blotting and HPLC. 5-LOX message and protein was detected in fibroblasts but not in platelets. Incubation with platelets markedly increased, already after one hour, the expression of 5-LOX in the fibroblast culture. The increased 5-LOX activity was associated with an elevated level of the 5-LOX metabolite 5-hydroxyeicosatetraenoic acid (5-HETE) reaching its maximum after 1-2 hours of co-incubation of fibroblasts and platelets. The 5-HETE production was reduced by the inhibitors DMDA, ETYA and ETI. In conclusion, this study suggests that platelet-stimulated proliferation of fibroblasts is mediated by an increased 5-LOX activity, which supports recent findings indicating a crucial role for this enzyme in proliferative disorders such as atherosclerosis. © 2006 Schattauer GmbH, Stuttgart.
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| 8. |
- Kälvegren, Hanna, et al.
(författare)
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Chlamydia pneumoniae induces nitric oxide synthase and lipoxygenase-dependent production of reactive oxygen species in platelets — effects on oxidation of low-density lipoproteins.
- 2005
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 94:2, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- There is increasing evidence that Chlamydia pneumoniae is linked to atherosclerosis and thrombosis. In this regard, we have recently shown that C. pneumoniae stimulates platelet aggregation and secretion, which may play an important role in the progress of atherosclerosis and in thrombotic vascular occlusion. The aims of the present study were to investigate the effects of C. pneumoniae on platelet-mediated formation of reactive oxygen species (ROS) and oxidation of low-density lipoprotein (LDL) in vitro. ROS production was registered as changes in 2´,7`-dichlorofluorescin- fluorescence in platelets with flow cytometry. LDL-oxidation was determined by measuring thiobarbituric acid reactive substances (TBARs). We found that C. pneumoniae stimulated platelet production of ROS.Polymyxin B treatment of C. pneumoniae, but not elevated temperature, abolished the stimulatory effects on platelet ROS- production, which suggests that chlamydial lipopolysaccharide has an important role. In hibition of nitric oxide synthase with nitro-L-arginine, lipoxygenase with 5,8,11-eicosatriynoic acid and protein kinase C with GF 109203X significantly lowered the production of radicals. In contrast, inhibition of NADPH-oxidase with di-phenyleneiodonium (DPI) did not affect the C. pneumoniae induced ROS-production. These findings suggest that the activities of nitric oxide synthase and lipoxygenase are the sources for ROS and that the generation is dependent of the activity of protein kinase C.The C. pneumoniae-induced ROS-production in platelets was associated with an extensive oxidation of LDL, which was significantly higher compared to the effect obtained by separate exposure of LDL to C. pneumoniae or platelets. In conclusion, C. pneumoniae interaction with platelets leading to aggregation, ROS-production and oxidative damage on LDL, may play a crucial role in the development of atherosclerotic cardiovascular disease.
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| 9. |
- Kälvegren, Hanna, et al.
(författare)
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Correlation between rises in Chlamydia pneumoniae-specific antibodies, platelet activation and lipid peroxidation after percutaneous coronary intervention.
- 2008
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Ingår i: European Journal of Clinical Microbiology and Infectious Diseases. - : Springer Science and Business Media LLC. - 0934-9723 .- 1435-4373. ; 27:7, s. 503-511
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Tidskriftsartikel (refereegranskat)abstract
- We recently showed that Chlamydia pneumoniae activates platelets in vitro, with an associated oxidation of low-density lipoproteins. The aim of this study was to investigate whether C. pneumoniae is released during percutaneous coronary intervention (PCI) and, thereby, causes platelet activation and lipid peroxidation. Seventy-three patients undergoing coronary angiography and following PCI or coronary artery bypass graft (CABG) and 57 controls were included in the study. C. pneumoniae antibodies, serotonin and lipid peroxidation were measured before and 24 h, 1 month and 6 months after angiography. The results show that serum C. pneumoniae IgA concentrations were significantly higher in patients than in the controls. Furthermore, in 38% of the C. pneumoniae IgG positive patients, the C. pneumoniae IgG concentration increased 1 month after PCI. The levels of C. pneumoniae IgG antibodies 1 month after PCI correlated with plasma-lipid peroxidation (r = 0.91, P < 0.0001) and platelet-derived serotonin (r = 0.62, P = 0.02). There was no elevation in the total serum IgG 1 month after PCI. In conclusion, the present results suggest that PCI treatment of coronary stenosis releases C. pneumoniae from the atherosclerotic lesions, which leads to platelet activation and lipid peroxidation.
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| 10. |
- Kälvegren, Hanna, et al.
(författare)
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Platelet activation triggered by Chlamydia pneumoniae is antagonized by 12-lipoxygenase inhibitors but not cyclooxygenase inhibitors.
- 2007
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999 .- 1879-0712. ; 566:1-3, s. 20-27
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Tidskriftsartikel (refereegranskat)abstract
- Chlamydia pneumoniae is a respiratory pathogen that has been linked to cardiovascular disease. We have recently shown that C. pneumoniae activates platelets, leading to oxidation of low-density lipoproteins. The aim of the present study was to evaluate the inhibitory effects of different pharmacological agents on platelet aggregation and secretion induced by C. pneumoniae.Platelet interaction with C. pneumoniae was studied by analyzing platelet aggregation and ATP-secretion with Lumi-aggregometry.Platelet aggregation and ATP-secretion induced by C. pneumoniae was markedly inhibited by the NO-donor S-nitroso-N-acetyl-d,l-penicillamine (SNAP), an effect that was counteracted by the guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). Pre-treatment of platelets with the 12-lipoxygenase (12-LOX) inhibitors cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) and 5,6,7-trikydroxyflavone (baicalein) completely blocked the activation, whereas the cyclooxygenase (COX) inhibitors 2-acetyloxybenzoic acid (aspirin) and (8E)-8-[hydroxy-(pyridin-2-ylamino)methylidene]-9-methyl-10,10-dioxo-10$l^(6)thia-9-azabicyclo[4.4.0]deca-1,3,5-trien-7-one (piroxicam) had no inhibitory effects. Opposite to C. pneumoniae-induced activation, platelets stimulated by collagen were inhibited by the COX-inhibitors but were unaffected by the 12-LOX-inhibitors. The platelet activating factor (PAF) antagonist Ginkgolide B blocked the C. pneumoniae-induced platelet activation, whereas the responses to collagen were unaffected. Furthermore, the P2Y1 and P2Y12 purinergic receptor antagonists 2'-deoxy-N6-methyladenosine 3',5'-bisphosphate (MRS2179) and N(6)-(2-methyl-thioethyl)-2-(3,3,3-trifluoropropylthio)-beta,gamma-dichloromethylene-ATP (cangrelor) inhibited the aggregation and secretion caused by C. pneumoniae.It is well-known that the efficacy of COX inhibitors in the prevention and treatment of cardiovascular disease varies between different patients, and that patients with low responses to aspirin have a higher risk to encounter cardiovascular events. The findings in this study showing that platelets stimulated by C. pneumoniae are unaffected by COX inhibitors but sensitive to 12-LOX inhibitors, may thus be of importance in future management of atherosclerosis and thrombosis.
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