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Biomedical subjects

Christian Stumpf

Publications and source records attributed to Christian Stumpf.

9 recordsLinked to original sources
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.

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PubMed2006

Enhanced platelet activation by prolactin in patients with ischemic stroke.

Prolactin and leptin are newly recognised platelet co-stimulators due to potentiation of ADP-induced platelet aggregation. Elevated leptin levels have recently been found to be a risk factor for ischemic stroke in both men and women, and especially in combination with increased blood pressure for hemorrhagic stroke in men. Until now an association between hyperprolactinemia and ischemic stroke has not been investigated systematically. We determined plasma prolactin and leptin levels as well as platelet P-selectin expression in 36 patients with ischemic stroke or transient ischemic attack and detected a significant correlation between increased prolactin values and enhanced ADP stimulated P-selectin expression on platelets. In contrast, no correlation of leptin values with platelet P-selectin expression was found. Next we determined plasma prolactin and leptin as well as acquired and congenital risk factors of thrombophilia in patients with first-ever non-hemorrhagic stroke with or without atrial fibrillation. Excluding patients with such preexisting risk factors, 21 patients with and 59 patients without atrial fibrillation were identified. Patients without atrial fibrillation revealed significantly higher plasma prolactin levels than patients with atrial fibrillation. Furthermore, the influence of aspirin or clopidogrel on prolactin stimulated P-selectin expression in vitro was tested, showing that aspirin was without effect, whereas clopidogrel significantly inhibited platelet P-selectin expression. In conclusion, hyperprolactinemia might be a novel risk factor for stroke mediating its thrombogenic effect through enhanced platelet reactivity, and this might correspond to a higher efficacy of antiplatelet combination therapy with clopidogrel compared to aspirin therapy alone.

Aged↗
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

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

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

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↗
PubMed2003

Enhanced levels of CD154 (CD40 ligand) on platelets in patients with chronic heart failure.

BACKGROUND: Inflammation plays a significant contributory role in the pathogenesis of chronic heart failure (CHF). Previous data have shown enhanced plasma levels of proinflammatory cytokines, i.e. TNF-alpha and IL-6, as well as a persistent immune activation in patients with CHF. Furthermore, the immune modulator CD154 has been receiving increased attention, since it plays a key role in the pathophysiology of multicellular vascular events such as thrombosis, inflammation and atherosclerosis. Since CD154 initiates and maintains the release of proinflammatory cytokines from endothelial cells, its potential role for the development and progression of CHF is of interest. METHODS: Fifty patients with CHF (aged 66.9+/-12.6 years, mean ejection fraction 22.1+/-9.2%, NYHA II-IV, 39 of ischemic origin, 11 with idiopathic dilated cardiomyopathy) and 15 healthy controls (aged 62.5+/-9.8 years) were examined. Thirty-two patients were taking aspirin (100 mg/day). Blood was drawn from a peripheral vein and immediately fixed with 1% paraformaldehyde, incubated with anti-CD154, anti-P-selectin, and anti-CD61 and thereafter analyzed by flow cytometry. RESULTS: Patients with CHF showed significantly enhanced expression of platelet-bound CD154 and P-selectin as compared to controls (CD154: median 35.6 25th percentile: 26.3; 75th percentile: 44.6 vs. 12.8; 25th: 6.8; 75th: 15.6 mean fluorescence intensity [MFI], P<0.001; P-selectin: median 3.2 25th percentile: 1.9; 75th percentile: 5.9 vs. 1.4; 25th: 1.2; 75th: 1.9, MFI, P<0.001). CD154 expression on platelets positively correlated with increasing NYHA-class. In contrast, no significant differences in serum levels of soluble CD154 or CD40 expression on monocytes were detected in the study groups. Antiplatelet-therapy with aspirin did not influence CD154 or P-selectin expression on platelets. CONCLUSION: Our pilot study demonstrates significantly enhanced levels of CD154 on platelets in patients with CHF. This suggests that the CD40-CD154 axis may contribute to the proinflammatory milieu, which exists in CHF and thus may play a pathogenic role in the development and progression of CHF.

Aged↗
PubMed2003

Decrease of serum levels of the anti-inflammatory cytokine interleukin-10 in patients with advanced chronic heart failure.

Inflammation plays a significant contributory role in the pathogenesis of chronic heart failure (CHF). Many studies have shown enhanced plasma levels of proinflammatory cytokines [i.e. tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6] in patients with CHF. However, there are only few reports on the regulation of anti-inflammatory cytokines such as IL-10. IL-10 has potent deactivating properties in macrophages and T-cells and thus acts as a down-regulator of cell-mediated immune responses. The aim of the present study was to assess whether serum concentrations of IL-10 significantly differ between patients with CHF and healthy control subjects. Patients with CHF [ n =50; 66.9+/-12.6 years; mean ejection fraction, 22.1+/-9.2%; New York Heart Association (NYHA) class II-IV] and 25 healthy controls (63.6+/-10.2 years) were examined. Of the 50 patients with CHF, 32 patients were taking aspirin (100 mg/day) and 33 patients had lipid-lowering therapy with a statin. Serum IL-10 as well as TNF-alpha concentrations were measured using commercially available immunoassays. Patients with CHF showed significantly lower IL-10 concentrations (2.3+/-1.9 compared with 5.2+/-2.3 pg/ml; P <0.001). Patients with advanced CHF (NYHA class III and IV) had the lowest IL-10 plasma levels. Aspirin and statin therapy did not significantly influence serum levels of IL-10. The ratio of TNF-alpha to IL-10 was significantly higher in patients with advanced CHF (NYHA class III and IV, ratio 3.2+/-1.2 and 3.1+/-1.1 respectively, compared with control 0.4+/-0.2; P <0.01). Our present study demonstrates significantly decreased serum levels of IL-10 in patients with advanced CHF. Since IL-10 is known as a potent anti-inflammatory cytokine, its decrease in advanced CHF may favour the inflammatory milieu in CHF.

Aged↗