Kateryna Sopova

Adipocytokines and CD34 progenitor cells in Alzheimer's disease.

Background Alzheimers disease (AD) and atherosclerosis share common vascular risk factors such as arterial hypertension and hypercholesterolemia. Adipocytokines and CD34+ progenitor cells are associated with the progression and prognosis of atherosclerotic diseases. Their role in AD is not adequately elucidated. Methods and Findings In the present study, we measured in 41 patients with early AD and 37 age- and weight-matched healthy controls blood concentrations of adiponectin and leptin by enzyme linked immunoabsorbent assay and of CD34+ progenitor cells using flow cytometry. We found significantly lower plasma levels of leptin in AD patients compared with the controls, whereas plasma levels of adiponectin did not show any significant differences (AD vs. control (mean±SD): leptin:8.9±5.6 ng/mL vs.16.3±15.5 ng/mL;P = 0.038; adiponectin:18.5±18.1 µg/mL vs.16.7±8.9 µg/mL;P = 0.641). In contrast, circulating CD34+ cells were significantly upregulated in AD patients (mean absolute cell count±SD:253±51 vs. 203±37; P = 0.02) and showed an inverse correlation with plasma levels of leptin (r = −0.248; P = 0.037). In logistic regression analysis, decreased leptin concentration (P = 0.021) and increased number of CD34+ cells (P = 0.036) were both significantly associated with the presence of AD. According to multifactorial analysis of covariance, leptin serum levels were a significant independent predictor for the number of CD34+ cells (P = 0.002). Conclusions Our findings suggest that low plasma levels of leptin and increased numbers of CD34+ progenitor cells are both associated with AD. In addition, the results of our study provide first evidence that increased leptin plasma levels are associated with a reduced number of CD34+ progenitor cells in AD patients. These findings point towards a combined involvement of leptin and CD34+ progenitor cells in the pathogenesis of AD. Thus, plasma levels of leptin and circulating CD34+ progenitor cells could represent an important molecular link between atherosclerotic diseases and AD. Further studies should clarify the pathophysiological role of both adipocytokines and progenitor cells in AD and possible diagnostic and therapeutic applications.

Dysregulation of Neurotrophic and Haematopoietic Growth Factors in Alzheimer's Disease: From Pathophysiology to Novel Treatment Strategies

Alzheimers disease (AD) is the leading cause of dementia in the elderly. Growth factors have been demonstrated to act in a synergistic way in angiogenesis and neurogenesis contributing to self-healing powers of the adult human brain. A growing body of evidence demonstrates that levels of many growth factors (neurotrophins and hematopoietins) are altered in cerebrospinal fluid and peripheral blood from AD patients and in animal models of AD. The present review summarizes the role of several neurotrophic growth factors (e.g., BDNF, SCF, NGF, GDNF) and haematopoietic growth factors (e.g., G-CSF, VEGF, SDF-1) in AD. Moreover, we summarize recent studies evaluating the diagnostic and prognostic value of growth factor levels in blood and cerebrospinal fluid in patients with AD and discuss the potential role of these growth factors as a promising new therapeutic approach in AD.

Amyloid-β peptides in plasma and cognitive decline after 1 year follow-up in Alzheimer's disease patients.

Plasma levels of amyloid-β (Aβ) peptides are potential biomarkers of early cognitive impairment and of Alzheimers disease (AD) risk. However, the association of Aβ peptides with the rate of cognitive decline in AD patients is still unclear. In the present study we demonstrate that Aβ₁₋₄₂ plasma levels show a significant correlation with the rate of cognitive decline and are significantly increased in AD patients with fast cognitive decline (decrease of Mini-Mental Status Examination (MMSE) score ≥ 5/year; n = 12) compared to AD patients with slow cognitive decline (decrease of MMSE score ≤ 4/year; n = 28), independent of baseline MMSE scores, age and cholinesterase inhibitor intake, but dependent on history of myocardial infarction and history of stroke in a multivariate analysis. These results suggest that Aβ₁₋₄₂ plasma levels are associated with the rate of cognitive decline in AD patients and may be influenced by atherosclerotic vasculopathies such as stroke and myocardial infarction.

Platelets in atherothrombosis--diagnostic and prognostic value of platelet activation in patients with atherosclerotic diseases.

Platelets and their activation have a pivotal role in the development of atherosclerotic diseases such as acute myocardial infarction (AMI), stroke and peripheral arterial occlusion. Biomarkers of platelet activation are making inroads into clinical studies and may serve as promising agents upstream to established downstream markers of myocardial necrosis such as troponin and creatin kinase. Targeting the degree of platelet activation assessed by the key collagen receptor of platelet activation, glycoprotein VI (GPVI), may have diagnostic and prognostic value for the assessement of high-risk groups of patients with symptomatic coronary artery disease and ischemic stroke and may be worthwhile to help to facilitate clinical decision-making and to rapidly initiate adequate therapy. The concert of platelet count, platelet activation, platelet aggregation and subsequent inflammation has had a significant impact on the clinical outcome in patients with atherosclerotic diseases. For a therapeutical approach to ameliorate prognosis, the use of antiplatelet treatment in particular in AMI patients with low response to clopidogrel has partly been overcome by novel second antiplatelet drugs on top of aspirin such as prasugrel and ticagrelor. Antiplatelet therapy may be adapted according to a GPVI-based platelet activity monitoring along with aggregometry of residual platelet aggregation. Other approaches using protease-activated receptor- 1 antagonists vorapaxar or atopaxar, which inhibit the platelet thrombin receptor, soluble GPVI called Revacept©, which blocks the collagen binding sites at the vascular lesion and anopheline saliva protein derived from the malaria vector mosquito, a platelet adhesion inhibitor independent of a GPVI mechanism, still wait for their breakthrough.

Plasma levels of stromal cell-derived factor-1 in patients with coronary artery disease: Effect of clinical presentation and cardiovascular risk factors

OBJECTIVE To investigate the possible association of plasma levels of stromal cell-derived factor-1 (SDF-1; CXCL12) with clinical presentation of symptomatic coronary artery disease (CAD) and with cardiovascular risk factors. METHODS A cath lab cohort of 492 consecutive patients with symptomatic CAD were recruited. Blood for plasma-SDF-1 determination was taken at the time of heart catheterization before percutaneous coronary intervention. RESULTS Plasma-SDF-1 was significantly decreased in ST-elevation myocardial infarction (STEMI) compared to stable angina pectoris (SAP) or to non-ST-elevation myocardial infarction (NSTEMI) (SAP vs. NSTEMI vs. STEMI: [pg/ml]: mean ± SD: 2110 ± 562 vs. 2127 ± 467 vs. 1834 ± 377; P < 0.001) independent of cardiovascular therapy. A weak correlation was observed between cholesterol levels and plasma SDF-1 in the whole study population. Left ventricular function and diabetes mellitus associated with plasma SDF-1 levels in patients with NSTEMI, while among STEMI patients, those with hyperlipidemia presented with even further decreased SDF-1 levels. CONCLUSION Plasma SDF-1 is significantly decreased in patients with STEMI, a fact which may reflect the importance of SDF-1 regulation in patients with acute myocardial infarction.

Expression of platelet‐bound stromal cell‐derived factor‐1 in patients with non‐valvular atrial fibrillation and ischemic heart disease

Summary.  Aims: Blood cell infiltration and inflammation are involved in atrial remodelling during atrial fibrillation (AF) although the exact mechanisms of inflammatory cell recruitment remain poorly understood. Platelet‐bound stromal cell‐derived factor‐1 (SDF‐1) is increased in cases of ischemic myocardium and regulates recruitment of CXCR4+ cells on the vascular wall. Whether platelet‐bound SDF‐1 expression is differentially influenced by non‐valvular paroxysmal or permanent atrial fibrillation (AF) in patients with stable angina pectoris (SAP) or acute coronary syndrome (ACS) has not been reported so far. Methods and results: A total of 1291 consecutive patients with coronary artery disease (CAD) undergoing coronary angiography were recruited. Among the patients with SAP, platelet‐bound‐SDF‐1 is increased in patients with paroxysmal AF compared with SR or to persistent/permanent AF (P < 0.05 for both). Platelet‐bound SDF‐1 correlated with plasma SDF‐1 (r = 0.488, P = 0.013) in patients with AF and ACS, which was more pronounced among patients with persistent AF (r = 0.842, P = 0.009). Plasma SDF‐1 was increased in persistent/permanent AF compared with SR. Patients with ACS presented with enhanced platelet‐bound‐SDF‐1 compared with SAP. Interestingly, among patients with ACS, patients with paroxysmal or persistent/permanent AF presented with an impaired platelet‐bound SDF‐1 expression compared with patients with SR. Conclusions: Differential expression of platelet‐bound and plasma SDF‐1 was observed in patients with AF compared with SR which may be involved in progenitor cell mobilization and inflammatory cell recruitment in patients with AF and ischemic heart disease. Further in vivo studies are required to elucidate the role of SDF‐1 in atrial remodeling and the atrial fibrillation course.

Platelets and platelet interaction with progenitor cells in vascular homeostasis and inflammation.

Platelet adhesion on vascular wall is the first step following vascular injury. Differential platelet secretion supports angiogenesis and vascular homeostasis. Progenitor cells are pluripotent cells responsible for tissue regeneration and wound healing. Upon ischemia bone marrow-derived progenitor cells are mobilized into peripheral circulation and domiciliate into peripheral organ vasculature and either give birth to a series of cardiovascular cells, including endothelial cells, macrophages, smooth muscle cells, or support in a paracrinic way the angiogenic capacity of local tissue cells. Mobilization, chemotaxis, adhesion, differentiation and interaction with vascular cells are essential steps of progenitor cell-mediated tissue repair. This review summarizes the recent advances in our understanding of platelet function with focus on interaction with progenitor cells and its role in cardiovascular homeostasis. Moreover, the role of platelet microparticles in progenitor cell function is separately addressed. Understanding the mechanisms of platelet interaction with progenitor cells provides us with new insights in the mechanisms of vascular homeostasis and possible new therapeutical targets supporting vascular repair.

Increased Myeloperoxidase Plasma Levels in Patients with Alzheimer's Disease

BACKGROUND Increasing evidence supports the role of cardiovascular risk factors in the development of Alzheimers disease (AD). OBJECTIVE In the present pilot study, we investigated plasma concentrations of myeloperoxidase (MPO) and its possible association with plasma amyloid-β (Aβ)1-42/1-40 ratio in AD patients and elderly healthy controls. METHODS The study sample included 28 AD patients and 27 elderly individuals with a normal cognitive status as a control group. The Mini-Mental Status Examination was used to determine the global cognition. MPO, Aβ1-40, and Aβ1-42 plasma concentrations were measured by enzyme linked immunoabsorbent assays. RESULTS AD patients showed significantly higher plasma concentrations of MPO in comparison to healthy elderly controls (AD versus healthy elderly controls (mean ± SD): 132.8 ± 114.8 ng/mL versus 55.0 ± 42.6 ng/mL; p = 0.002). MPO plasma concentrations showed a significant positive correlation in the whole sample with the presence of AD (ρ = 0.428, p < 0.001) and its stage (ρ = 0.331; p = 0.013) as well as with plasma concentrations of Aβ1-42 (ρ = 0.406; p = 0.004) and Aβ1-42/1-40 ratio (ρ = 0.354; p = 0.013). In a binary logistic regression model, plasma MPO concentrations were independently associated with the presence of AD (p = 0.014). CONCLUSION AD patients showed significantly increased plasma levels of MPO, which could be an important molecular link between atherosclerosis and AD. Further studies should evaluate whether MPO may also be a useful biomarker and potential new treatment target in AD.

Platelet Activation in Alzheimer’s Disease: From Pathophysiology to Clinical Value

Vascular risk factors and atherosclerosis are critically involved in dementia development of both vascular and Alzheimers type. However, the exact mechanisms linking atherosclerosis and the development of Alzheimers disease (AD) are still unknown. As platelet activation and adhesion on vascular wall is the first step of vascular inflammation and atherosclerosis, it appears tempting to hypothesize that platelets could be the link between vascular risk factors/ atherosclerosis and AD. In recent years, much work has been accomplished to elucidate the role of platelets in AD. The present review will summarize and highlight the latest findings of this research area and provide novel insight and understanding in the association between platelet activation and AD.

Different Effects of Ranibizumab and Bevacizumab on Platelet Activation Profile

Purpose: The aim of the study was to evaluate the potential influence of ranibizumab and bevacizumab on platelet activation and aggregation, which are critical processes in the pathogenesis of arterial thromboembolic events (ATEs). Methods: For the assessment of platelet function, flow cytometry and aggregometry were employed. Platelets were isolated from healthy volunteers and exposed to ranibizumab (1 mg/ml and 150 ng/ml) and bevacizumab (2.5 mg/ml and 3 μg/ml) or their solvents for 10 and 30 min prior to the addition of TRAP (25 μM), PAR-4-AP (25 μM) or thrombin (0.02 U/ml). The surface expression of activated GP IIb/IIIa, P-selectin (CD62P) and platelet-bound stromal cell-derived factor-1 (SDF-1) was measured on resting (nonactivated) and activated platelets by flow cytometry. The platelet aggregation capacity was examined using light transmission aggregometry. Results: The expression of surface activation markers did not differ significantly between nonstimulated and TRAP-, PAR-4-AP- or thrombin-activated platelets after incubating with ranibizumab. However, GP IIb/IIIa, CD62P and SDF-1 were significantly downregulated in PAR-4-AP- and thrombin-activated platelets after exposure to bevacizumab 2.5 mg/ml. In addition, ranibizumab- and bevacizumab-FITC were significantly increased in all activated platelets. No significant differences were observed in the aggregation of activated platelets after incubation with ranibizumab or bevacizumab. Conclusion: All ranibizumab concentrations as well as the bevacizumab concentration of 3 μg/ml had no influence on platelet activation and aggregation. Therefore, this in vitro study did not show any relationship between the exposition of activated platelets to ranibizumab or bevacizumab and the development of ATEs. However, the highest level of bevacizumab interfered with platelet activation, leading to downregulation of platelet activation markers. This observation might explain why the systemic treatment with high-dose bevacizumab could be associated with an increased risk of bleeding. Regarding the use of lower intravitreal dosages, further research should focus on the complex interactions between platelets and other cells, such as endothelial cells, which might stronger relate to a potentially increased risk of ATEs and depend on systemic vascular endothelial growth factor levels. Facing the different activation profiles, the diverse effects of the drugs on the cellular level have to be critically scrutinized for their clinical relevance.