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Biomedical subjects

Christoph D Garlichs

Publications and source records attributed to Christoph D Garlichs.

At least 19 recordsLinked to original sources
PubMed2007

Accumulation of immune cells and high expression of chemokines/chemokine receptors in the upstream shoulder of atherosclerotic carotid plaques.

The presence of immune cells is important for plaque destabilization. Disturbed flow conditions were shown to enhance the recruitment of circulating immune cells. Thus, we analyzed in 54 atherosclerotic carotid plaques the frequency of different immune cells, HLA-DR, chemokines, and chemokine receptors, comparing the upstream with the downstream plaque shoulder. The presence of neovascularization and intraplaque hemorrhages was investigated by CD34 immunostaining and Mallory's iron stain. Immunohistochemical analyses were performed to detect smooth muscle cells (SMC: actin), macrophages (CD68), T cells (CD3), dendritic cells (DC: fascin), mature DC (CD83), and the expression of HLA-DR, chemokine receptors (CCR-2, CCR-6), and chemokines (MCP-1, MIP-3alpha). Significantly more SMC were detected downstream than upstream (p<0.001). In contrast, significantly more macrophages (p=0.01), DC (p=0.03), mature DC (p=0.007), and a higher expression of HLA-DR (p=0.004), CCR-2 (p=0.002), CCR-6 (p<0.001), MCP-1 (p=0.04), and MIP-3alpha (p=NS) were observed upstream than downstream. Immune cells were strongly associated with neovascularization. The abundance of SMC downstream provides an explanation for distal plaque growth. Enhanced recruitment of immune cells through neovessels into the upstream shoulder might be contributing to plaque destabilization.

Aged↗
PubMed2007

Actin-dependent regulation of connective tissue growth factor.

Expression of connective tissue growth factor (CTGF) in endothelial cells is modulated by shear stress affecting the organization of the cytoskeleton. The molecular connection between alterations of actin and CTGF expression was investigated in human umbilical vein endothelial cells (HUVEC) and a microvascular endothelial cell line. Overexpression of nonpolymerizable monomeric actin R62D interfered with stress fiber formation in HUVEC and concomitantly reduced immunoreactive CTGF. In microvascular endothelial cells, flow-dependent upregulation of CTGF was prevented by this actin mutant. In contrast, overexpression of actin S14C strengthened filamentous actin and increased CTGF expression. These data indicated an inverse relationship between CTGF expression and monomeric actin. Coexpression of the mutant actins and different CTGF promoter constructs revealed an actin-sensitive site between 3 and 4.5 kb of the CTGF promoter. A CArG-like box at -3791 bp was responsible for actin-dependent CTGF induction as shown by mutagenesis. Overexpression of actin S14C activated the nonmutated promoter significantly more strongly than the mutated promoter. Actin polymerization is regulated by the small GTPase RhoA and activation of serum response factor (SRF). Overexpression of constitutively active RhoA or SRF significantly increased CTGF protein synthesis. The 4.5-kb promoter construct, but not the construct with a mutation in the CArG box, was activated by SRF or RhoA, providing evidence for a functional role of this site in CTGF induction. These findings provide novel evidence that monomeric actin is the connecting link between alterations in the cytoskeleton and CTGF gene expression and demonstrate the importance of SRF in regulating CTGF transcription.

Actins↗
PubMed2006

Decrease in circulating myeloid dendritic cell precursors in coronary artery disease.

OBJECTIVES: We analyzed the frequency of myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) precursors in blood of patients with coronary artery disease (CAD) and in atherosclerotic carotid plaques of patients with cerebrovascular disease (CVD). BACKGROUND: Circulating DC precursors are reduced in several autoimmune diseases. Atherosclerosis has features of an autoimmune disease, such as the presence of autoantibodies or autoreactive T cells. Tissue-resident DCs were previously described in atheromata, and it is assumed that they are important for the activation of T cells against autoantigens there. METHODS: Circulating mDC and pDC precursors were flow cytometrically detected in healthy controls (n = 19), CAD patients with stable (n = 20) and unstable angina pectoris (n = 19), and acute myocardial infarction (n = 17). In human carotid plaques (n = 65), mDC and pDC precursors were identified immunohistochemically. RESULTS: Circulating mDC precursors were significantly reduced in patients with stable angina pectoris (0.19%, p = 0.04), unstable angina pectoris (0.16%, p = 0.004), and acute myocardial infarction (0.08%, p < 0.001) compared with control patients (0.22% of peripheral blood mononuclear cells). In contrast, pDC numbers were not significantly altered. Circulating mDC precursors inversely correlated with high-sensitivity C-reactive protein (r = -0.38, p = 0.001) or interleukin-6 (r = -0.42, p < 0.001). In contrast to pDC, significantly more mDC precursors were observed in vulnerable carotid plaques (24, 0.25 mm2; n = 31; p = 0.003) than in stable ones (6.4, 0.25 mm2; n = 34). CONCLUSIONS: Similar to autoimmune diseases, circulating mDC precursors were significantly reduced in patients with CAD. The emergence of mDC precursors in vulnerable plaques suggests their recruitment into atheromata as a possible reason for their decrease in blood. In contrast, no significant association of circulating pDC precursors with atherosclerosis was observed.

Aged↗
PubMed2006

[Gene polymorphisms leading to calcified and stenotic aortic valves].

In the Caucasian world calcified and stenosed aortic valves are a common disease. Due to increasing life expectancy prevalence of aortic valve disease will increase dramatically. In order to establish alternative therapeutic approaches to valve replacement, we have to get a better understanding of the pathophysiological process and genetic determinations leading to calcified and stenotic valve disease. Exploring these genetic determinations will open new specific fields of therapeutic modulations of the disease process. In the literature, different gene polymorphisms have been characterized to develop calcifications and further stenosis of the aortic valves.Here, congestive polyvalent aortic valve abnormalities without specific genetic determinations (i. e., DiGeorge syndrome or fragile x syndrome), autosomal inherited alterations leading to congestive aortic valve disease (i. e., Williams-Beuren syndrome, Gaucher's disease, tetralogy of Fallot, genetic aberrations of chromosomes 2 and 4 as well as trisomy 18), X- and Y-chromosomal specific alterations (i. e., Turner syndrome), congestive structure-based aortic valve disease (i. e., bicuspid aortic valve with regard to hand-heart syndromes, tetracuspid aortic valve associated with DiGeorge syndrome) and genetic mutations of specific target genes (i. e., epidermal growth factor receptor, NOTCH-1, elastin, angiotensin I conversion enzyme, beta-glucocerebrosidase, interleukin-10, chemokine receptor 5, connective tissue growth factor, transforming growth factor beta1, vitamin D receptor, estrogen receptor-alpha, apolipoproteins A1, B, and E) are summarized. The roles of gene polymorphism in the development of calcified and stenosed aortic valve appear slowly in the understanding of the process leading to the valve disease and are mainly based on studies of supravalvular and bicuspid aortic valve stenoses. New molecular biological methods enabling broad gene expression analyses demonstrate the similarity in the pathophysiology of atherosclerotic vessel inflammation, bone formation/fibrosis, with the processes leading to stenosed and calcified aortic valves. Based on to-date knowledge, further analyses have to be done and will improve understanding of the pathophysiological processes with regard to the development of new therapeutic drug targets.

Aortic Valve↗
PubMed2006

Connective tissue growth factor is released from platelets under high shear stress and is differentially expressed in endothelium along atherosclerotic plaques.

Connective tissue growth factor (CTGF) is overexpressed in atherosclerotic blood vessels. To further investigate the role of CTGF in atherosclerosis, we examined whether CTGF is released from platelets by high shear stress, and whether the expression of CTGF along the atherosclerotic lesions depends on local hemodynamic conditions. Human platelets were subjected to 10 dyn/cm2 or 120 dyn/cm2 and analysed by Western blotting. Furthermore, longitudinal sections of 25 carotid plaques were immunohistochemically analysed for the endothelial expression of CTGF. A very low CTGF amount was secreted from platelets at low shear stress (11.4 +/- 3.9% of total CTGF in platelets). On the contrary, high shear stress caused a markedly increased CTGF release from platelets (29 +/- 13.8%, p = 0.07 vs low shear stress, n = 4). Immunohistochemical analyses showed that the mean numbers of CTGF-positive endothelial cells were significantly higher up-stream as compared with down-stream regions of the luminal surface of atherosclerotic vessels (21.3 +/- 3.6 vs 13.9 +/- 2.8 down-stream, p < 0.001). Moreover, in plaques undergoing intimal neovascularization, newly formed vessels accumulated particularly in up-stream parts of the lesions. In conclusion, this study demonstrated that CTGF is released from platelets by high shear stress. Furthermore, disturbed flow along atherosclerotic vessels may induce endothelial CTGF expression and contribute to the progress of atherosclerotic lesions.

Atherosclerosis↗
PubMed2005

Differential effects of statins on relevant functions of human monocyte-derived dendritic cells.

Statins were shown to possess immunomodulating properties, but the mechanisms of statin effects on the immune system are poorly understood. We analyzed the influence of statins on professional antigen-presenting dendritic cells (DC). Immature DC were cultivated from monocytes of healthy donors. DC maturation was induced by lipopolysaccharide (LPS; 1 microg/mL). Unstimulated and LPS-stimulated DC were treated with simvastatin or atorvastatin (0.1-1 microM). The expression of CD40, CD83, CD86, and human leukocyte antigen-DR on unstimulated and LPS-stimulated DC was reduced significantly by statins, and the expression of Toll-like receptor 2 (TLR2) and TLR4 on LPS-stimulated DC was enhanced temporarily. Statins caused a significant reduction of endocytosis of fluorescein isothiocyanate-dextran by DC. Statins significantly inhibited the basal secretion of interleukin (IL)-6, IL-8, IL-12, and tumor necrosis factor alpha from unstimulated DC, and their release from LPS-stimulated DC was enhanced. In mixed leukocyte reaction, preincubation of LPS-stimulated DC with statins significantly suppressed their clustering with T cells and their ability to induce T cell proliferation, CD71, and CD25 up-regulation on T cells and the secretion of interferon-gamma and IL-2 from T cells. In conclusion, this study showed that statins suppressed endocytosis, basal secretion of proinflammatory cytokines, and the ability of DC to induce T cell proliferation, activation, and T helper cell type 1 differentiation. However, statin preincubation of LPS-stimulated DC caused a further increase in their secretion of proinflammatory cytokines.

Antigen Presentation↗
PubMed2005

ACE inhibition lowers angiotensin-II-induced monocyte adhesion to HUVEC by reduction of p65 translocation and AT 1 expression.

Angiotensin-converting enzyme (ACE) inhibitors interfere with several key events of vascular inflammation resulting in impressive reductions in coronary vascular events. However, in human arteries ACE inhibitors block the production of angiotensin II (AngII) incompletely because of the involvement of alternative pathways in local AngII formation. Therefore, our study concentrated on the presumed modulation by ACE inhibition of local AngII-mediated inflammatory actions by a mechanism independent of blockage of AngII formation. We analyzed the effect of the ACE inhibitor ramiprilat on AngII-dependent cell adhesion molecule (CAM) expression and adhesion of monocytic THP-1 cells to endothelial cells. AngII induced upregulation of P-selectin, VCAM-1 and ICAM-1 on endothelial cells via activation of AT 1, which was correlated with enhanced THP-1 adhesion in flow chamber assays. Both enhanced adhesion and adhesion molecule expression were significantly reduced by pretreatment with ramiprilat. Ramiprilat reduced AT 1 expression on endothelial cells and decreased the AngII-induced p65 translocation into the nucleus. Diminished AT 1 expression and adhesion molecule expression in response to ramiprilat treatment were partially reversed after incubation with a bradykinin 2 receptor antagonist, suggesting that elevated bradykinin levels under ACE inhibition may be involved in the beneficial effect of ACE inhibitors. Thus, modulation of the local AngII system by ramiprilat may at least in part contribute to the benefits of ACE inhibition in the treatment of atherosclerotic diseases.

Adrenergic beta-Antagonists↗
PubMed2005

Connective tissue growth factor is overexpressed in complicated atherosclerotic plaques and induces mononuclear cell chemotaxis in vitro.

OBJECTIVE: Atherosclerotic blood vessels overexpress connective tissue growth factor (CTGF) mRNA, but the role of CTGF in atherosclerosis remains controversial. To assess the hypothesis that CTGF is involved in atherosclerotic plaque progression, we investigated CTGF protein expression and distribution in the different types of plaque morphology. METHODS AND RESULTS: Serial cross-sections of 45 human carotid plaques were immunohistochemically analyzed for the presence of CTGF protein, neovascularization (von Willebrand factor), macrophages (CD68), and T cells (CD3). The lesions were categorized according to American Heart Association (AHA) classification as fibrous (type IV and V) or complicated plaques (type VI). The levels of CTGF were significantly higher in complicated compared with fibrous plaques (P=0.002). CTGF accumulated particularly in the rupture-prone plaque shoulder and in the areas of neovascularization or infiltration with inflammatory cells. Macrophage-like cells stained positive for CTGF protein in plaques. Subsequent in vitro studies showed that although monocyte-derived macrophages do not produce CTGF on stimulation with transforming growth factor-beta, lipopolysaccharide, or thrombin, they take it up from culture medium. Furthermore, CTGF induces mononuclear cell chemotaxis in a dose-dependent manner. CONCLUSIONS: CTGF protein is significantly increased in complicated compared with fibrous plaques and may enhance monocyte migration into atherosclerotic lesions, thus contributing to atherogenesis.

Aged↗
PubMed2005

The expression of macrophage migration inhibitory factor 1alpha (MIF 1alpha) in human atherosclerotic plaques is induced by different proatherogenic stimuli and associated with plaque instability.

OBJECTIVES: Macrophage migration inhibitory factor 1alpha (MIF), a cytokine with immunoregulatory functions has been suggested to be involved in atherosclerotic plaque development. However, little is known about MIF-inducing conditions in the atherosclerotic process and the association of MIF with plaque instability. METHODS AND RESULTS: Forty-two carotid endatherectomy samples from 36 patients and 4 aortic samples from young accident victims (as healthy controls) were analyzed for MIF staining. MIF expressing tissues in the atherosclerotic plaques are mainly mononuclear cells (MNCs), but also endothelial cells of intimal microvessels (MVECs). The magnitude and the intensity of their MIF expression was associated with the progression of plaques from early lesions (Stary I-III) to complicated plaque stages (Stary IV-VIII). In highly inflammatory and neovascularized regions of the plaques the colocalization of MIF expressing MNCs with CD40-L+ and angiotensin II (Ang II)-producing MNCs could be established. This finding supports the notion that CD40-L fusion protein and Ang II are able to induce MIF production in the monocytic cell line THP-1. Furthermore hypoxia (< or =1% O2) as a further proinflammatory and especially proangiogenetic factor was able to stimulate MIF secretion by THP-1, human monocytes and HUVECs. Hyperglycemia and insulin remained without effect. CONCLUSION: MIF is expressed in advanced atherosclerotic lesions in close correlation with signs of instability, such as mononuclear cell inflammation and neointimal microvessel formation. Furthermore, the colocalization of MIF with Ang II-producing MNCs and CD40-L+ cells in these plaques and the finding that proathero- and -angiogenic mediators such as CD40-L, Ang II and hypoxia are able to stimulate MIF expression in vitro suggest an important role of MIF in the modulation of atherosclerotic plaque stability.

Aged↗
PubMed2005

Enhanced levels of platelet P-selectin and circulating cytokines in young patients with mild arterial hypertension.

BACKGROUND: Emerging evidence links inflammation to atherosclerosis (AS). Although some studies have addressed the role of inflammation in patients with arterial hypertension (AH), its overall contribution in AH is far from being understood. Therefore, the present pilot study was designed to examine the role of platelet P-selectin and various inflammatory mediators in young patients with moderate AH without signs of target organ damage. METHODS AND RESULTS: Fifteen patients with mild AH [33.8 +/- 7.3 years, mean arterial pressure (MAP) 106.6 +/- 10.4 mmHg] and 15 healthy normotensive controls (31.7 +/- 10.6 years) were examined. Platelet P-selectin was analysed by flow cytometry. Plasma levels of monocyte-chemoattractant-protein-1 (MCP-1), high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, tumour necrosis factor alpha (TNFalpha), and IL-10 levels were measured by enzyme immunoassay (EIA). Patients with mild AH showed significantly enhanced expression of platelet P-selectin [17.2 +/- 5.4 versus 10.6 +/- 4.2 mean fluorescence intensity (MFI), P < 0.001]. P-selectin expression positively correlated with MAP (r = 0.43, P < 0.05). Furthermore, patients with mild AH had significantly enhanced plasma levels of hsCRP (2.7 +/- 3.8 versus 0.6 +/- 0.9 mg/l, P < 0.01), IL-6 (1.4 +/- 0.7 versus 0.6 +/- 0.3 pg/ml, P < 0.001), TNFalpha (2.8 +/- 0.7 versus 2.4 +/- 0.4 pg/ml, P < 0.05), and MCP-1 (291.3 +/- 100.7 versus 214.3 +/- 8.3 pg/ml, P < 0.05). IL-6 levels positively correlated with hsCRP levels (r = 0.47, P < 0.05) and mean arterial pressure (MAP) (r = 0.44, P < 0.05). CONCLUSIONS: This pilot study demonstrates that in an early stage of AH, inflammatory pathways are already activated. Besides pro-inflammatory cytokines, platelets seem to play a significant role in mediating inflammation in AH, which could lead to target organ injury. Further investigations have to clarify the role of early anti-inflammatory therapy, in patients with mild to moderate AH, in alleviating hypertensive target organ damage.

Adult↗
PubMed2004

ACE inhibition lowers angiotensin II-induced chemokine expression by reduction of NF-kappaB activity and AT1 receptor expression.

OBJECTIVE: Angiotensin converting enzyme (ACE) inhibitors significantly improve survival in patients with atherosclerosis. Although ACE inhibitors reduce local angiotensin II (AngII) formation, serine proteases form AngII to an enormous amount independently from ACE. Therefore, our study concentrates on the effect of the ACE-inhibitor ramiprilat on chemokine release, AngII receptor (ATR) expression, and NF-kappaB activity in monocytes stimulated with AngII. METHODS AND RESULTS: AngII-induced upregulation of IL-8 and MCP-1 protein and RNA in monocytes was inhibited by the AT1R-blocker losartan, but not by the AT2R-blocker PD 123.319. Ramiprilat dose-dependently suppressed AngII-induced upregulation of IL-8 and MCP-1. The suppressive effect of ramiprilat on AngII-induced chemokine production and release was in part caused by downregulation of NF-kappaB, but more by a selective and highly significant reduced expression of AT1 receptors as shown in monocytes and endothelial cells. CONCLUSION: In our study we demonstrated for the first time that ramiprilat reduced expression of AT1R in monocytes and endothelial cells. In addition, ramiprilat downregulated NF-kappaB activity and thereby reduced the AngII-induced release of IL-8 and MCP-1 in monocytes. This antiinflammatory effect, at least in part, may contribute to the clinical benefit of the ACE inhibitor in the treatment of coronary artery disease.

Angiotensin II↗
PubMed2004

Monitoring the cellular effects of HMG-CoA reductase inhibitors in vitro and ex vivo.

OBJECTIVE: Inhibition of 3hydroxy3methylglutaryl-coenzyme A (HMG-CoA) reductase by statins and the subsequent reduction in Rho protein isoprenylation inactivates these important signaling molecules. The purpose of this study was to directly monitor statin effects on Rho proteins. METHODS AND RESULTS: We used biphasic Triton X-114 system, 1-dimensional isoelectric focusing, and 2D-electrophoresis for the separation of modified and nonmodified Rho proteins. These methods were evaluated in human fibroblasts treated with simvastatin. 2D-electrophoresis, which proved to be the most sensitive method, revealed 2 major spots of identical molecular weight but different isoelectric points, with the more basic spot representing the carboxymethylated form of RhoA. In control cells, 90% of RhoA was fully modified (carboxymethylated). After treatment with simvastatin, a significant shift toward the unmethylated form was observed, representing inhibition of isoprenylation, which is a prerequisite to further modification. Similar shifts were observed for Rac1 and Cdc42. In freshly isolated peripheral blood mononuclear cells, a shift toward nonmodified RhoA was observed after treatment with atorvastatin in vitro and in vivo. There was a significant increase in unmethylated RhoA in statin-treated individuals versus control individuals. CONCLUSIONS: 2D-electrophoresis is a sensitive method for detecting changes in the amount of nonisoprenylated Rho proteins, allowing monitoring the direct cellular effects of statins.

Cell Line↗
PubMed2004

Atorvastatin induces tissue transglutaminase in human endothelial cells.

Tissue transglutaminase (tTgase) contributes to the organisation of the basement membrane and is therefore thought to be important for the integrity and stability of the vessel wall. In the present study, we hypothesised that the HMG-CoA reductase inhibitor atorvastatin may up-regulate the tTgase expression in endothelial cells and thereby exert beneficial effects on endothelial function. Treatment of human umbilical vein endothelial cells (HUVEC) with atorvastatin (1-10 microM) caused a clear increased expression of tTgase in both permeabilised and non-permeabilised HUVEC. In contrast, stimulation of HUVEC with TNFalpha had no substantial effect on tTgase expression or localisation but inhibited the atorvastatin-induced up-regulation and externalisation of tTgase. Propidium iodide staining revealed that statin-induced apoptosis is not responsible for the enhanced expression. By inducing the expression of tTgase, statins may promote tTgase-mediated stabilisation of the basement membrane. This effect of atorvastatin may contribute to the beneficial role of statins on endothelial function.

Apoptosis↗
PubMed2004

HMG-CoA reductase inhibitors suppress maturation of human dendritic cells: new implications for atherosclerosis.

The beneficial effects of statins in atherosclerosis have been partly attributed to their immunomodulating functions. Dendritic cells (DC), which are "professional" antigen-presenting cells, were recently detected in atherosclerotic plaques. It is assumed that DC play a critical role in the immunological processes related to atherosclerosis. Thus, we investigated the effects of statins on maturation and antigen-presenting function of DC. Human monocyte-derived DC were incubated with simvastatin or atorvastatin (1-10microM) for different periods (1-48h), and were subsequently stimulated with a cytokine cocktail (1.25ng/ml TNF-alpha, 1ng/ml Il-1beta, and 0.5microg/ml prostaglandin E(2)) to induce maturation. In contrast to untreated DC, statin-preincubated DC exhibited an immature phenotype and a significantly lower expression of the maturation-associated markers CD83, CD40, CD86, HLA-DR, and CCR7. The inhibitory statin effect was completely reversed by mevalonate or geranylgeranyl pyrophosphate. In addition, preincubation with statins significantly reduced the ability of cytokine-stimulated DC to induce T cell proliferation. In the present study, we have shown that statins inhibit the maturation and antigen-presenting function of human myeloid dendritic cells, thus maybe contributing to their beneficial effects in atherosclerosis. Therefore, the use of statins as immunomodulators might also provide a new therapeutic approach to other immunological disorders.

Adjuvants, Immunologic↗
PubMed2004

Induction of connective tissue growth factor (CTGF) in human endothelial cells by lysophosphatidic acid, sphingosine-1-phosphate, and platelets.

Endothelial dysfunction is characterized by multiple interactions between endothelial cells and components of the blood. This study focussed on the induction of the pro-atherogenic connective tissue growth factor (CTGF) in endothelial cells by bioactive lipids and platelets. Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) led to a time- and concentration-dependent increase in CTGF mRNA and protein expression in the human endothelial cell line EAHY 926 and in primary cultures of human umbilical vein endothelial cells (HUVEC). As both cell types expressed various receptors for LPA and S1P, signaling pathways were further characterized by pharmacological means: induction of CTGF was pertussis toxin-insensitive and inhibition of activation of p42/44 MAP kinases only partially reduced CTGF expression. On the contrary, interference with the RhoA signaling pathway by simvastatin, an inhibitor of geranylgeranyltransferases, or the Rho-kinase inhibitor Y27632 prevented induction of CTGF. Co-incubation of endothelial cells with freshly isolated human platelets significantly increased the expression of CTGF mRNA in endothelial cells, which was also sensitive to simvastatin. Up-regulation of CTGF in endothelial cells, induced by LPA, S1P, or platelets, may contribute to the initiation and progression of atherosclerosis. Interference of simvastatin with the synthesis of this pro-atherogenic factor further supports the anti-atherogenic role of statins.

Blood Platelets↗
PubMed2004

Emergence of dendritic cells in rupture-prone regions of vulnerable carotid plaques.

Dendritic cells (DC), which are critically involved in various immunological disorders, were detected in atherosclerotic plaques in 1995. Since DC might be related to the immunological processes in atherosclerosis (AS), we analyzed the emergence of DC and other inflammatory cells in different stages of AS. Serial cross-sections of 44 carotid specimens were immunohistochemically analyzed for the presence of DC, T cells, macrophages, and HLA-DR. Atherosclerotic specimens were histologically defined as initial lesions, advanced stable, or vulnerable plaques. In initial lesions significantly lower DC numbers were detected than in advanced plaques (P < 0.001). For advanced plaques, DC numbers were significantly higher in vulnerable than in stable plaques (P = 0.005). In contrast to initial lesions, approximately 70% of DC in advanced plaques exhibited a mature phenotype (CD83+, DC-LAMP+), indicating a functional activity of DC. In plaques of patients with acute ischemic symptoms DC numbers were markedly elevated (P = 0.03), whereas significantly lower DC numbers and more often a stable plaque morphology were detected in statin-treated patients (P = 0.02). DC clusters with a strong HLA-DR expression and frequent DC-T cell contacts were located particularly in the rupture-prone plaque regions and at complications. The results of the present study indicate that DC might contribute to plaque destabilization through an activation of T cells.

Aged↗
PubMed2004

Activated human platelets release connective tissue growth factor.

Connective tissue growth factor (CTGF) is overexpressed in wound healing, fibrosis and advanced atherosclerotic lesions. Platelets adhere to CTGF, suggesting that this protein may be involved in the formation of platelet-rich thrombi at the sites of tissue injury or atherosclerotic plaque rupture. Since platelets contain a wide array of biologically active proteins, we investigated the presence, localization and release of CTGF from these cells. For this purpose, human platelets from healthy donors were washed and stimulated with thrombin or ADP. Following incubation, proteins from unstimulated and stimulated cell lysates and the supernatants were analysed by Western blotting. The experiments showed that unstimulated platelets contain considerable amounts of CTGF, whereas no CTGF was detectable in platelet-poor plasma. To elucidate the origin of CTGF in platelets, we performed immunohistochemical analysis of human bone marrow sections. The analysis showed that although CTGF protein is widely expressed in bone marrow cells, it is not expressed by platelet-producing megakaryocytes, suggesting that CTGF presence in platelets is a result of endocytosis from extracellular environment in bone marrow. Agonist-stimulation of platelets resulted in a significant release of CTGF from the storage granules, with thrombin at 0.1 U/mL being a more potent activator than ADP at 20 micro mol/L. The agonist-dependent CTGF secretion was significantly inhibited by aspirin. In conclusion, CTGF is stored in normal human platelets, and can be released upon platelet activation. Aspirin treatment prevents CTGF release, suggesting that clinical benefits of this drug may involve the inhibition of CTGF secretion.

Adenosine Diphosphate↗