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ABSTRACT: A high-fat diet disturbs the composition and function of the gut microbiota and generates local gut-associated and also systemic responses. Intestinal mast cells, for their part, secrete mediators which play a role in the orchestration of physiological and immunological functions of the intestine. Probiotic bacteria, again, help to maintain the homeostasis of the gut microbiota by protecting the gut epithelium and regulating the local immune system. In the present study, we explored the effects of two probiotic bacteria, Lactobacillus rhamnosus GG (GG) and Propionibacterium freudenreichii spp. shermanii JS (PJS), on high fat-fed ApoE*3Leiden mice by estimating the mast cell numbers and the immunoreactivity of TNF-α and IL-10 in the intestine, as well as plasma levels of several markers of inflammation and parameters of lipid metabolism. We found that mice that received GG and PJS exhibited significantly lower numbers of intestinal mast cells compared with control mice. PJS lowered intestinal immunoreactivity of TNF-α, while GG increased intestinal IL-10. PJS was also observed to lower the plasma levels of markers of inflammation including vascular cell adhesion molecule 1, and also the amount of gonadal adipose tissue. GG lowered alanine aminotransferase, a marker of hepatocellular activation. Collectively, these data demonstrate that probiotic GG and PJS tend to down-regulate both intestinal and systemic pro-inflammatory changes induced by a high-fat diet in this humanised mouse model.
The British journal of nutrition 12/2012; · 3.45 Impact Factor
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ABSTRACT: Accumulating work in experimental animals suggests that bradykinin (BK) exerts cardioprotective effects via bradykinin type-2 receptors (BK-2Rs). In human end-stage heart failure, BK-2Rs are significantly downregulated by mechanisms that have remained elusive. Heart tissues from idiopathic dilated cardiomyopathy (IDC; n = 7), coronary heart disease (CHD; n = 6), and normal patients (n = 6) were analyzed by RT-PCR, SSCP, and Western blotting. In normal and IDC hearts, BK-2R expression increased with age, with a lower relative increase in IDC hearts. BK-2R mRNA and protein levels showed a positive linear correlation, suggesting transcriptional regulation. Two known BK-2R promoter polymorphisms, -58T/C and -9/+9, were found to be present in the study population. The allelic frequencies for the C-allele in -58T/C were 0.58 in normal and CHD hearts and 0.81 in IDC hearts. Furthermore, the allelic frequencies for the -9 and +9 alleles were 0.42 and 0.58 in normal hearts and 0.64 and 0.36 in IDC hearts, respectively. All analyzed CHD hearts were homozygous for the -9 allele. Thus, the expression of cardioprotective BK-2Rs in human hearts is increased with age in normal and IDC hearts and may be regulated on the transcriptional level. Moreover, comparison of normal subjects and patients with failing hearts revealed different allelic frequencies in each of two known BK-2R gene polymorphisms.
International journal of vascular medicine 01/2012; 2012:159646.
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ABSTRACT: Bradykinin type 2 receptor (BK-2R) knockout mice develop microvascular dysfunction and cardiac hypertrophy. In aged human cardiac microvascular endothelium, dysfunction develops before heart failure symptoms. Since endothelial aging is an independent risk factor for cardiovascular disease, we aimed to clarify the role of kinin receptors in age-related endothelial senescence.
Using qRT-PCR, a downregulation of BK-2Rs during senescence of cultured human coronary artery endothelial cells (HCAECs) and rat cardiac microvascular endothelial cells (RCMECs) was observed. BK-2R downregulation was associated with a decreased cell proliferation rate, with a growth arrest phenotype and reduced angiogenic potential. By staining senescence-associated β-galactosidase, RCMECs from old spontaneously hypertensive rats (SHRs) were found to be significantly more senescent than those derived from age-matched WKY rats, albeit their telomere lengths were similar. Despite downregulation of BK-2Rs and BK-1Rs, a novel family member GPR-100 was highly expressed in HCAECs throughout the culture period.
Aging cardiac endothelial cells gradually lose their capacity to express BK-2Rs, and this loss appears to be parallel with a loss of the angiogenic potential of the aging cells. Since RCMECs from hypertensive rats showed premature senescence, hypertension may predispose to cardiac dysfunction by accelerating endothelial aging.
Journal of Vascular Research 01/2012; 49(1):13-23. · 2.65 Impact Factor
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ABSTRACT: Human atherosclerotic lesions contain mast cells and immunoglobulin G immune complexes containing oxidized low-density lipoproteins (oxLDL-IgG ICs). Here we studied whether such oxLDL-IgG ICs can activate human mast cells and induce them to express and secrete pro-inflammatory cytokines that are potentially capable of inducing and amplifying atherogenic processes.
Incubation of cultured human mast cells in the presence of oxLDL-IgG ICs led to a significant dose-dependent upregulation of the expression and secretion of tumor necrosis factor-alpha (TNF-a) and interleukin-8 (IL-8), and the chemotactic cytokine monocyte chemoattractant protein-1 (MCP-1). The secretory responses were dose-dependent and associated with moderate release of histamine and tryptase, which are preformed mast cell mediators contained in the cytoplasmic secretory granules of the cells. Also native LDL-IgG ICs induced similar pro-inflammatory cytokine response, suggesting that ICs per se are important for the IgG IC-induced mast cell activation.
Mast cells in atherosclerotic lesions which also contain oxLDL-IgG ICs may become activated by the ICs and secrete many pro-inflammatory cytokines. Our results suggest that intimal mast cells act as a cellular link between oxLDL-IgG ICs and the inflammatory response in atherosclerosis.
Atherosclerosis 02/2011; 214(2):357-63. · 3.79 Impact Factor
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ABSTRACT: To investigate the effects of four probiotic bacteria and their combination on human mast cell gene expression using microarray analysis.
Human peripheral-blood-derived mast cells were stimulated with Lactobacillus rhamnosus (L. rhamnosus) GG (LGG(®)), L. rhamnosus Lc705 (Lc705), Propionibacterium freudenreichii ssp. shermanii JS (PJS) and Bifidobacterium animalis ssp. lactis Bb12 (Bb12) and their combination for 3 or 24 h, and were subjected to global microarray analysis using an Affymetrix GeneChip(®) Human Genome U133 Plus 2.0 Array. The gene expression differences between unstimulated and bacteria-stimulated samples were further analyzed with GOrilla Gene Enrichment Analysis and Visualization Tool and MeV Multiexperiment Viewer-tool.
LGG and Lc705 were observed to suppress genes that encoded allergy-related high-affinity IgE receptor subunits α and γ (FCER1A and FCER1G, respectively) and histamine H4 receptor. LGG, Lc705 and the combination of four probiotics had the strongest effect on the expression of genes involved in mast cell immune system regulation, and on several genes that encoded proteins with a pro-inflammatory impact, such as interleukin (IL)-8 and tumour necrosis factor alpha. Also genes that encoded proteins with anti-inflammatory functions, such as IL-10, were upregulated.
Certain probiotic bacteria might diminish mast cell allergy-related activation by downregulation of the expression of high-affinity IgE and histamine receptor genes, and by inducing a pro-inflammatory response.
World Journal of Gastroenterology 02/2011; 17(6):750-9. · 2.47 Impact Factor
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ABSTRACT: To examine the proangiogenic potential of myofibroblasts and mast cells, 2 types of cells present in human aortic valves.
Aortic valve stenosis is an active atheroinflammatory disease, characterized by the accumulation of inflammatory cells and the neovascularization of the valves. A total of 85 stenotic valves and 20 control valves were obtained during valve replacement surgery. The results of immunohistochemistry analysis revealed stenotic aortic valves that contained 3 types of neovessels: small microvessels, medium microvessels, and organized arterioles. The distribution density of the neovessels was significantly higher in stenotic valves than in control valves (P<0.001) and correlated positively with valvular calcification gradus (r=0.26, P=0.02) and mast cell density (r=0.38, P<0.001). In the neovascularized areas of stenotic aortic valves, mast cells contained vascular endothelial growth factor and were degranulated, indicating their activation. The stimulation of cultured myofibroblasts derived from aortic valves with a mast cell-preconditioned medium, hypoxic culture conditions, or tobacco smoke all induced vascular endothelial growth factor secretion in the myofibroblasts. Finally, mast cell tryptase was able to degrade the antiangiogenic molecule endostatin in vitro.
Mast cells and myofibroblasts may accelerate the progression of aortic valve stenosis by altering the balance between angiogenic and antiangiogenic factors in the valves, thus promoting valvular neovascularization.
Arteriosclerosis Thrombosis and Vascular Biology 03/2010; 30(6):1220-7. · 6.37 Impact Factor
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ABSTRACT: Accumulating in vitro and in vivo studies have proposed a role for mast cells in the pathogenesis of atherosclerosis. Here, we studied the role of mast cells in lipoprotein metabolism, a key element in the atherosclerotic disease. Male mice deficient in low-density lipoprotein receptors and mast cells on a Western diet for 26 weeks had significantly less atherosclerotic changes both in aortic sinus (55%, P = 0.0009) and in aorta (31%, P = 0.049), as compared to mast cell-competent littermates. Mast cell-deficient female mice had significantly less atherosclerotic changes in aortic sinus (43%, P = 0.011). Furthermore, we found a significant positive correlation between the extent of atherosclerosis and the number of adventitial/perivascular mast cells in aortic sinus of mast cell-competent mice (r = 0.615, P = 0.015). Serum cholesterol and triglyceride levels were significantly lower in both male (63%, P = 0.0005 and 57%, P = 0.004) and female (73%, P = 0.00009 and 54%, P = 0.007) mast cell-deficient mice, with a concomitant decrease in atherogenic apoB-containing particles and serum prebeta-high-density lipoprotein and phospholipid transfer protein activity in both male (69% and 24%) and female (74% and 54%) mast cell-deficient mice. Serum soluble intercellular adhesion molecule was decreased in both male (32%, P = 0.004) and female (28%, P = 0.003) mast cell-deficient mice, whereas serum amyloid A was similar between mast cell-deficient and competent mice. In conclusion, mast cells participate in the pathogenesis of atherosclerosis in ldlr(-/-) mice by inducing both an atherogenic lipid profile and vascular inflammation.
Journal of Cellular Biochemistry 12/2009; 109(3):615-23. · 2.87 Impact Factor
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ABSTRACT: Bradykinin receptors are differentially expressed in the coronary vascular endothelium of rat and human hearts during the pathogenesis of heart failure, but the mechanisms responsible for this regulation have remained vague. Here we show by quantitative real-time PCR, Western blot analysis, and immunohistochemistry, that hypoxia triggers the expression of bradykinin type-2 receptors (BK-2Rs) in cultured human coronary artery endothelial cells (HCAECs), in isolated rat cardiac microvascular endothelial cells (RCMECs), and in rat hearts subjected to ligation of the left anterior descending coronary artery. Mild hypoxia (5% O(2)) induced a fourfold temporal increase in BK-2R mRNA expression in HCAECs, which was also observed at the protein level, whereas severe hypoxia (1% O(2)) slightly inhibited the mRNA expression of BK-2Rs. In addition, HOE-140, a BK-2R antagonist, inhibited mRNA and protein expression of BK-2Rs. The BK-2Rs induced by mild hypoxia were biologically active, that is, capable of inducing intracellular production of nitric oxide (NO) upon activation of HCAECs with bradykinin (BK), a response attenuated by HOE-140. In rat hearts recovering from myocardial infarction, BK-2Rs were upregulated in the endothelium of vessels forming at the border zone between fibrotic scar tissue and healthy myocardium. Furthermore, in an in vitro wound-healing assay, RCMEC migration was increased under mild hypoxic culture conditions in the presence of BK and was attenuated with HOE-140. Our present results show that mild hypoxia triggers a temporal expression of functional BK-2Rs in human and rat endothelial cells and support a role for BK-2Rs in hypoxia-induced angiogenesis.
Journal of Cellular Physiology 07/2009; 221(2):359-66. · 3.87 Impact Factor
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ABSTRACT: A broad variety of microbes are present in atherosclerotic plaques and chronic bacterial infection increases the risk of atherosclerosis by mechanisms that have remained vague. One possible mechanism is that bacteria or bacterial products activate plaque mast cells that are known to participate in the pathogenesis of atherosclerosis. Here, we show by real-time PCR analysis and ELISA that Chlamydia pneumoniae (Cpn) and a periodontal pathogen, Aggregatibacter actinomycetemcomitans (Aa), both induce a time and concentration-dependent expression and secretion of interleukin 8 (IL-8), tumour necrosis factor-alpha (TNF-alpha) and monocyte chemoattractant protein-1 (MCP-1) by cultured human peripheral blood-derived mast cells, but not anti-inflammatory molecules, such as IL-10 or transforming growth factor beta 1 (TGF-beta 1). The IL-8 and MCP-1 responses were immediate, whereas the onset of TNF-alpha secretion was delayed. The Cpn-mediated pro-inflammatory effect was attenuated when the bacteria were inactivated by UV-treatment. Human monocyte-derived macrophages that were pre-infected with Cpn also induced a significant pro-inflammatory response in human mast cells, both in cocultures and when preconditioned media from Cpn-infected macrophages were used. Intranasal and intravenous administration of live Cpn and Aa, respectively induced an accumulation of activated mast cells in the aortic sinus of apolipoprotein E-deficient mice, however, with varying responses in the systemic levels of lipopolysaccharide (LPS) and TNF-alpha. Pro-atherogenic Cpn and Aa induce a pro-inflammatory response in cultured human connective tissue-type mast cells and activation of mouse aortic mast cells in vivo.
Journal of Cellular and Molecular Medicine 03/2008; 13(1):103-13. · 4.13 Impact Factor
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ABSTRACT: Activated mast cells (MCs) induce endothelial cell (EC) apoptosis in vitro and are present at sites of plaque erosions in vivo. To further elucidate the role of MCs in endothelial apoptosis and consequently in plaque erosion, we have studied the molecular mechanisms involved in MC-induced EC apoptosis.
Primary cultures of rat cardiac microvascular ECs (RCMECs) and human coronary artery ECs (HCAECs) were treated either with rat MC releasate (ie, mediators released on MC activation), rat chymase and tumor necrosis factor-alpha (TNF-alpha), or with human chymase and TNF-alpha, respectively. MC releasate induced RCMEC apoptosis by inactivating the focal adhesion kinase (FAK) and Akt-dependent survival signaling pathway, and apoptosis was partially inhibited by chymase and TNF-alpha inhibitors. Chymase avidly degraded both vitronectin (VN) and fibronectin (FN) produced by the cultured RCMECs. In addition, MC releasate inhibited the activation of NF-kappaB (p65) and activated caspase-8 and -9. Moreover, in HCAECs, human chymase and TNF-alpha induced additive levels of apoptosis.
Activated MCs induce EC apoptosis by multiple mechanisms: chymase inactivates the FAK-mediated cell survival signaling, and TNF-alpha triggers apoptosis. Thus, by inducing EC apoptosis, MCs may contribute to plaque erosion and complications of atherosclerosis.
Arteriosclerosis Thrombosis and Vascular Biology 03/2008; 28(2):309-14. · 6.37 Impact Factor
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ABSTRACT: Chemically modified tetracyclines (CMTs) are a group of nonantimicrobial derivatives of tetracycline, which exert antiproliferative and anticollagenolytic properties. The molecular mechanisms, however, are poorly understood.
The effect of CMT-3 on cultured, subconfluent rat aortic smooth muscle cells (SMCs) was analyzed by [(3)H]-thymidine incorporation, counting cell numbers, and flow cytometry analysis.
CMT-3 inhibited the incorporation of [(3)H]-thymidine and reduced the cell number dose-dependently, with approximately 60% inhibition at the maximal CMT-3 concentration used (20 mumol/l). CMT-3 decreased the SMC proportion in S-phase and gradually increased the proportion at G2/M. Initially, the proportion of cells in G1-phase increased and then gradually decreased back to baseline as the CMT-3 concentration increased. CMT-3 treatment of confluent SMCs for 24 h did not induce apoptosis.
CMT-3 inhibited SMC proliferation by inducing cell cycle arrest at the G2/M restriction point. Nonetheless, CMT-3 did not induce SMC apoptosis.
Coronary Artery Disease 01/2008; 18(8):663-7. · 1.24 Impact Factor
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ABSTRACT: To examine the role of the complement system, a source of powerful proinflammatory mediators, in aortic valve stenosis (AS).
Stenotic aortic valves (n=24) were obtained at valve replacement surgery, and non-stenotic (n=12) and early sclerotic (n=4) valves at cardiac transplantations. The terminal complement complex C5b-9 was stained by immunohistochemistry. Expression of the anaphylatoxin receptors C3aR and C5aR was studied in the valves by immunohistochemistry and RT-PCR, and in isolated valve myofibroblasts after stimulation with potential AS-accelerating factors (TNF-alpha and cigarette smoke) by RT-PCR. Cultured myofibroblasts were exposed to C3a, and their secretion of proinflammatory cytokines was assessed by ELISA. C5b-9 was found already in early aortic valve lesions, and its deposition was augmented in advanced stenotic valves. In stenotic valves, expression of C3aR mRNA was upregulated (p<0.05) and strong staining of C3aR and C5aR was detected. Myofibroblasts in stenotic, but not in control valves, expressed C3aR, and, in isolated myofibroblasts, TNF-alpha and cigarette smoke induced C3aR mRNA expression (p<0.05 for both). Stimulation of myofibroblasts with C3a resulted in enhanced secretion of MCP-1 (p<0.001), IL-6 (p=0.003), and IL-8 (p=0.03).
In stenotic aortic valves, complement is activated leading to generation of the anaphylatoxins C3a and C5a. Upregulation of C3aR in the valves as a result of inflammation and external risk factors, such as cigarette smoke, leads to an inflammatory response in aortic valve myofibroblasts. Complement activation in stenotic valves emerges as a novel pathogenic component of AS and may serve as a therapeutic target in this disease.
Atherosclerosis 01/2008; 196(1):190-200. · 3.79 Impact Factor
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ABSTRACT: Cardioprotective bradykinin type-2 receptors (BK-2Rs) are downregulated in the myocardial endothelium of both human and rat failing hearts. Statins are cardioprotective drugs that reduce the level of plasma cholesterol but also exert cholesterol-independent pleiotropic effects. Here we examined the effect of lovastatin on BK-2R expression in cultured human coronary artery endothelial cells. The effect of lovastatin on the expression of BK receptors in human coronary artery endothelial cells (HCAECs) was examined by real-time PCR, Western blot analysis and immunocytochemistry. Lovastatin induced a time- and concentration-dependent increase in both BK-2R and BK-1R mRNA expression in the cultured HCAECs. Also, the number of functional BK-2Rs capable of inducing BK-mediated NO production and cGMP signaling was increased in the lovastatin-treated HCAECs. Mevalonate, the direct metabolite of HMG-CoA reductase, reversed the effect of lovastatin. Furthermore, lovastatin inhibited Rho activation and a selective inhibitor of Rho-associated kinases, Y-27632, induced a similar increase in BK-2R expression as lovastatin. In contrast, a specific inhibitor of COX-2, NS398, significantly inhibited the lovastatin-induced expression of BK-2Rs. Here we show for the first time that lovastatin induces the expression of BK-2Rs in cultured human coronary artery endothelial cells through a novel cholesterol-independent pleiotropic mechanism that involves RhoA kinase inhibition and COX-2 activation. Thus, reported beneficial effects of statins in cardiovascular diseases may be partly mediated by an increased expression of cardioprotective BK-2Rs in the endothelial cells of the coronary tree. Moreover, the use of COX-2 inhibitors may affect the level of endothelial BK-2Rs in a negative fashion.
Journal of Molecular and Cellular Cardiology 12/2007; 43(5):593-600. · 5.17 Impact Factor
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ABSTRACT: To summarize the current understanding of the pathobiology of aortic valve stenosis and portray the major advances in this field.
Stenotic aortic valves are characterized by atherosclerosis-like lesions, consisting of activated inflammatory cells, including T lymphocytes, macrophages, and mast cells, and of lipid deposits, calcific nodules, and bone tissue. Active mediators of calcification and cells with osteoblast-like activity are present in diseased valves. Extracellular matrix remodeling, including collagen synthesis and elastin degradation by matrix metalloproteinases and cathepsins, contributes to leaflet stiffening. In experimental animals, hypercholesterolemia induces calcification and bone formation in aortic valves, which can be inhibited by statin treatment. The potential of statins to retard progression of aortic valve stenosis has also been recognized in clinical studies; however, further prospective trials are needed. Angiotensin II-forming enzymes are upregulated in stenotic valves. Angiotensin II may participate in profibrotic progression of aortic valve stenosis and may serve as a possible therapeutic target.
Recent findings regarding the interaction of inflammatory cells, lipids, mediators of calcification, and renin-angiotensin system in stenotic valves support the current opinion of aortic valve stenosis being an actively regulated disease, potentially amenable to targeted molecular therapy. Evidence from prospective clinical studies is eagerly awaited.
Current Opinion in Lipidology 11/2007; 18(5):483-91. · 6.09 Impact Factor
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ABSTRACT: In aortic stenosis (AS), adverse remodelling of the valves may depend on altered local regulation of pro- and antifibrotic systems. We have recently shown that angiotensin-converting enzyme (ACE), which generates profibrotic angiotensin II and inactivates antifibrotic bradykinin (BK), is upregulated in stenotic aortic valves. Here, we analyse the expression of neutral endopeptidase (NEP), another profibrotic and BK-degrading enzyme, and of BK receptors in aortic valves in AS.
Stenotic aortic valves (n = 86) were obtained at valve replacement surgery and control valves (n = 13) at cardiac transplantation. Expression levels of NEP and BK type 1 and 2 receptors (BK-1R and BK-2R) in aortic valves and in isolated valvular myofibroblasts were analysed by real-time PCR and immunohistochemistry, and NEP activity was quantified by autoradiography. NEP, BK-1R, and BK-2R mRNA levels were higher in stenotic than in non-stenotic valves (P < 0.05 for each) and the respective proteins localized to valvular endothelial cells and myofibroblasts. In stenotic valves, the proteolytic activity of NEP was significantly increased (4.5-fold, P < 0.001), and tumour necrosis factor-alpha induced the expression of NEP in cultured myofibroblasts. Finally, treatment of cultured myofibroblasts with an NEP inhibitor (phosphoramidon) downregulated the expression of profibrotic transforming growth factor-beta1, whereas addition of BK decreased the expression of collagens I and III which was reversed by a BK-2R antagonist.
NEP activity is increased in stenotic aortic valves in parallel with increased expression of BK-receptors. The upregulation of NEP and BK-1R have the potential to promote valvular fibrosis and remodelling while the increase in BK-2R may represent a compensatory antifibrotic response. These findings add novel pathogenic insight and raise potential new therapeutic targets in AS.
European Heart Journal 08/2007; 28(15):1894-903. · 10.48 Impact Factor
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ABSTRACT: Increasing evidence suggests that cathepsins and angiotensin II (AngII) participate in atherosclerosis, particularly in remodeling of the extracellular matrix of the inflamed arterial intima. Here, we show that AngII induces mRNA expression of cathepsin F, a member of the cysteine protease family, in human monocyte-derived macrophages. AngII did not affect the amount of intracellular cathepsin F protein, but significantly enhanced its secretion by the treated cells. The stimulatory effect of AngII was mediated by the AngII type 2 (AT(2)) receptor, as demonstrated by the ability of the AT(2)-receptor antagonist PD123319 to block the AngII-induced increase in cathepsin F secretion. Our present data demonstrate a novel proatherogenic role for AngII, namely its ability to enhance secretion of lysosomal cathepsin F by monocyte-derived macrophages.
Atherosclerosis 07/2007; 192(2):323-7. · 3.79 Impact Factor
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ABSTRACT: Osteoprotegerin (OPG) and the receptor activator of nuclear factor-kappaB ligand (RANKL), two cytokines regulating bone remodeling, have recently been raised as potential pathogenetic factors in cardiovascular diseases. We have studied circulating and myocardial OPG and RANKL in patients having severe aortic stenosis (AS) with or without heart failure (HF).
We studied 131 adults with AS. Blood was sampled from the aortic root, coronary sinus, and femoral vein at cardiac catheterization. LV myocardial biopsies were taken at surgery. Plasma OPG and soluble (s)RANKL were analyzed by ELISA, and myocardial OPG and RANKL by RT-PCR and immunohistochemistry.
Circulating OPG was elevated in AS patients with HF, the association being independent of age, sex, and presence of coronary artery disease (beta=0.17, p=0.033). Elevated plasma OPG decreased after valve replacement in patients with preoperative HF (p=0.0005). Relative to its concentration in the aortic root, plasma OPG was reduced in the coronary sinus (p<0.05) and in the femoral vein (p<0.001), these arteriovenous gradients being accentuated in HF (p=0.003).
HF due to LV pressure overload in AS increases circulating OPG and augments OPG extraction by the heart and peripheral tissues. OPG may be involved in the pathogenesis of HF and could serve as a useful biomarker in HF due to LV pressure overload.
European Journal of Heart Failure 05/2007; 9(4):357-63. · 4.90 Impact Factor
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ABSTRACT: Modified lipoproteins induce inflammatory reactions in the atherosclerotic arterial wall. We have previously found that macrophages in atherosclerotic lesions secrete lysosomal hydrolases that can modify low-density-lipoprotein (LDL) in vitro to generate "hydrolase-modified LDL" (H-LDL). Here, we studied whether H-LDL exerts inflammatory effects on cultured human macrophages.
Using cytokine cDNA arrays, we found that H-LDL induced expression of IL-8, but not of the anti-inflammatory cytokines IL-10 and transforming growth factor (TGF)-beta, in human monocyte-derived macrophages. H-LDL induced rapid phosphorylation of the p38 mitogen-activated protein kinase (MAPK), nuclear translocation of 2 transcription factors, nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1), and time-dependent secretion of IL-8 from the macrophages. Inhibition of MAPKs and of transcription factors showed that p38 MAPK and NF-kappaB, but not ERK1/2, JNK, or AP-1, were crucial for the H-LDL-induced IL-8 secretion from the macrophages.
The results show that by activating p38 MAPK and NF-kappaB, macrophage hydrolases modify LDL into biologically active particles capable of triggering the secretion of IL-8 in macrophages. Thus, activated hydrolase-secreting macrophages in atherosclerotic lesions may sustain a proatherogenic extracellular environment by hydrolyzing LDL and triggering it to act in an autocrine or paracrine fashion to induce IL-8 secretion by the plaque macrophages.
Arteriosclerosis Thrombosis and Vascular Biology 12/2006; 26(11):2504-9. · 6.37 Impact Factor
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ABSTRACT: Endothelial erosion has emerged as an important contributor to the pathogenesis of atherosclerosis and its complications, but the molecular mechanisms have remained unclear. As activated mast cells capable of secreting neutral proteases are present in the intima of eroded coronary plaques, we investigated their potential roles in endothelial erosion.
Studies involving double immunostaining of mast cells (tryptase(pos) cells) and platelets (CD42b) in human coronary artery specimens indicated that the number of subendothelial mast cells correlated with the number of parietal microthrombi (P=0.001, rs 0.27). The number of parietal microthrombi was significantly higher (P<0.001) in areas of plaques than in areas of healthy intima. Of the microthrombi 86% were in the lesional coronary segments, of all subendothelial mast cells 15% were located under parietal microthrombi, and of all parietal microthrombi 49% were located over subendothelial mast cells. Double immunostaining revealed the mast cell to neutrophil ratio in the human coronary artery intima to be 5 : 1, and that mast cells are a major local source of cathepsin G. Scanning electron and light microscopy indicated that treatment of fresh human coronary arteries intraluminally with recombinant human (rh)-tryptase and rh-chymase induced endothelial damage characterized by retraction of endothelial cells, disruption of endothelial cell to cell adhesions and desquamation of endothelial cells. VE-cadherin and fibronectin, which are necessary for cell-cell interactions and endothelial cell adhesion, were degraded by tryptase and chymase and also by cathepsin G.
Activated subendothelial mast cells may contribute to endothelial erosion by releasing proteases capable of degrading VE-cadherin and fibronectin.
Coronary Artery Disease 12/2006; 17(7):611-21. · 1.24 Impact Factor
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ABSTRACT: Synovial fibroblast is the key cell type in the growth of the pathological synovial tissue in arthritis. Here, we show that platelet-derived growth factor (PDGF) is a potent mitogen for synovial fibroblasts isolated from patients with rheumatoid arthritis. Inhibition of PDGF-receptor signalling by imatinib mesylate (1muM) completely abrogated the PDGF-stimulated proliferation and inhibited approximately 70% of serum-stimulated proliferation of synovial fibroblasts. Similar extent of inhibition was observed when PDGF was neutralized with anti-PDGF antibodies, suggesting that imatinib mesylate does not inhibit pathways other than those mediated by PDGF-receptors. No signs of apoptosis were detected in synovial fibroblasts cultured in the presence of imatinib. These results suggest that imatinib mesylate specifically inhibits PDGF-stimulated proliferation of synovial fibroblasts, and that inhibition of PDGF-receptors could represent a feasible target for novel antirheumatic therapies.
Biochemical and Biophysical Research Communications 09/2006; 347(1):31-5. · 2.48 Impact Factor
