advanceCOR (Germany)

Abstract Background Whether plasma levels of soluble glycoprotein VI (sGPVI) are able to predict ischemic or bleeding risk in patients with chronic coronary syndrome (CCS) undergoing percutaneous coronary intervention (PCI) is not known. The objective of this study was to answer this question. Material and methods The present study included 317 patients out of 334 patients of the ISAR-PLASTER trial (randomized trial of 2 doses of revacept vs. placebo), who underwent PCI for CCS and had baseline plasma sGPVI levels available. Patients were categorized into three groups according to tertiles of sGPVI: low (n = 106; sGPVI ≤ 9.5 ng/ml), intermediate (n = 106; sGPVI ≤ 16.2 ng/ml) and high tertile of sGPVI (n = 105; sGPVI ≥ 16.5 ng/ml). The composite of death and myocardial injury (MI) at 48 hours after randomization served as a measure of ischemic risk, and Bleeding Academic Research Consortium (BARC) type 1 to 5 bleeding at 30 days as a measure of bleeding risk. Results and conclusions Baseline plasma levels of sGPVI (before PCI and revacept administration) correlated with bleeding (bleeding incidence among low, intermediate and high sGPVI tertile: 11.8%, 13.6%, and 25.8%, respectively; P = 0.005), but not with ischemic events (incidence of death/MI among low, intermediate and high sGPVI tertile: 25.0%, 21.9%, and 26.9%, respectively; P = 0.70). Revacept did not interact with these associations. Elevated plasma sGPVI levels are associated with an increased risk of bleeding but not ischemic complications after PCI in patients with CCS. Funding German Center for Cardiovascular Research, Deutsches Herzzentrum München, Federal Ministry of Education and Research, and advanceCOR.

Histological examination of targets in regions of interest in histological sections is one of the most frequently used tools in biomedical research. However, it is a technical challenge to secure a multitarget section for inspection of the structure’s mutual relationship of targets or a longitudinally filamentous- or tubular-formed tissue section for visitation of the overall morphological features. We present a method with a specified cutting plane and place, allowing researchers to cut directly at the multitarget centers accurately and quickly. The method is proven to be reliable with high accuracy and reproducibility and a low coefficient of variation, testing on repeat experiments of three target’s position-known models. With this method, we successfully yielded single sections containing whole intraorbital optical nerves, three aortic valves, or whole thoracic tracheas in their central positions. The adjoined custom-made tools used in the study, such as various tissue-specific formulated calibrated trimming and embedding guides, an organ-shaped cavity plaster mold, and a two-time embedding technique for optimal and identical trimming or embedding, also bear great potential to become a common supplemental tool for traditional histology and may contribute to the reduction of the labor, and the number of animals needed.

Patients with stroke or transient ischemic attacks (TIAs) and internal carotid artery stenosis harbor an increased risk of recurrent stroke especially within 2 weeks after the first event. In addition, the revascularization procedure itself (carotid endarterectomy [CEA] or carotid artery stenting [CAS]) is associated with both clinically apparent and silent brain infarctions, mainly caused by the embolic nature of the ruptured carotid plaque. The glycoprotein VI (GPVI) fusion protein Revacept is a highly specific antithrombotic drug without direct inhibition of systemic platelet function that might reduce periprocedural distal embolization from the vulnerable ruptured plaque located at the internal carotid artery. By shielding collagen at the site of vascular injury, Revacept inhibits plaque-mediated platelet adhesion and aggregation, while not directly affecting systemic hemostasis. In this phase II study, 158 patients with symptomatic carotid artery stenosis with recent TIA or stroke were randomized to receive a single dose of either Revacept (40 or 120 mg) or placebo. All patients were on standard secondary preventive therapy (statins and platelet inhibition) and underwent CEA, CAS, or best medical therapy according to current guidelines. The efficacy of Revacept was evaluated by exploratory assessment of new diffusion-weighted imaging lesions on magnetic resonance imaging after the revascularization procedure; a combination of cardiovascular events (ischemic and hemorrhagic stroke, TIA, myocardial infarction, or coronary intervention) and bleeding complications served to assess clinically critical patients' outcome and safety. This exploratory phase II randomized, double-blind clinical trial provides valuable insights on the safety, tolerability, and efficacy of Revacept in patients with symptomatic carotid artery stenosis.

Blood-derived microRNA signatures have emerged as powerful biomarkers for predicting and diagnosing cardiovascular disease, cancer, and metabolic disorders. Platelets and platelet-derived microvesicles are a major source of microRNAs. We have previously shown that the inappropriate anticoagulation and storage of blood samples causes substantial platelet activation that is associated with the release of platelet-stored molecules into the plasma. However, it is currently unclear if circulating microRNA levels are affected by artificial platelet activation due to suboptimal plasma preparation. To address this issue, we used a standardized RT-qPCR test for 12 microRNAs (thrombomiR®, TAmiRNA GmbH, Vienna, Austria) that have been associated with cardiovascular and thrombotic diseases and were detected in platelets and/other hematopoietic cells. Blood was prevented from coagulating with citrate–theophylline–adenosine–dipyridamole (CTAD), sodium citrate, or ethylenediaminetetraacetic acid (EDTA) and stored for different time periods either at room temperature or at 4 °C prior to plasma preparation and the subsequent quantification of microRNAs. We found that five microRNAs (miR-191-5p, miR-320a, miR-21-5p, miR-23a-3p, and miR-451a) were significantly increased in the EDTA plasma. Moreover, we observed a time-dependent increase in plasma microRNAs that was most pronounced in the EDTA blood stored at room temperature for 24 h. Furthermore, significant correlations between microRNA levels and plasma concentrations of platelet-stored molecules pointed towards in vitro platelet activation. Therefore, we strongly recommend to (i) use CTAD as an anticoagulant, (ii) process blood samples as quickly as possible, and (iii) store blood samples at 4 °C whenever immediate plasma preparation is not feasible to generate reliable data on blood-derived microRNA signatures.

Introduction: A novel long-term murine model for Graves’ disease (GD) using repeated, long-term immunizations with recombinant adenovirus expressing the extracellular A-subunit of the human thyrotropin receptor (Ad-TSHR) was applied to evaluate the functional anti-TSHR-antibody (TSHR-Ab) profile. Methods: BALB/c mice received 7 immunizations with either 10¹⁰ plaque-forming units of Ad-TSHR or control Ad-GFP. Naïve (nonimmuized native) mice were also studied. Three 3-weekly immunizations were followed by 4-weekly boosts until the 7th immunization. Blocking (TBAb) and stimulating (TSAb) TSHR-Ab were measured with bioassays. Assay cut-offs for TBAb/TSAb were at 34% inhibition and a specimen-to-reference ratio (SRR) of 140%. Results: Nineteen (8 Ad-TSHR-, 4 Ad-GFP-immunized, and 7 native) mice were investigated. All native mice were negative for TSHR-binding inhibitory immunoglobulins (TBII) prior to immunization. Native and Ad-GFP mice were negative in weeks 17 and 27 for TBII and TBAb/TSAb. In native mice, the free thyroxine (fT4) levels (median [25th percentile; 75th percentile]) were in the upper normal range (1.2 ng/mL [1.1; 1.6]) prior to immunization, at weeks 17 (2.2 ng/mL [2.1; 2.4]) and 27 (1.4 ng/mL [1.1; 1.7]), respectively. In contrast, in Ad-TSHR-immunized mice, fT4 values were markedly increased at weeks 17 (4.4 ng/mL [3.9; 6]) and 27 (4.5 ng/mL [4.2; 6]) compared to those in Ad-GFP mice (2 ng/mL [1.8; 2.1] and 1.4 ng/mL [1.1; 1.6]), respectively (p = 0.0008, p = 0.001). In contrast, at week 17, in Ad-TSHR mice, the mean TBII, TBAb, and TSAb levels were 40 IU/L (40; 40); 62% inhibition (38; 69), and 116% SRR (97; 185), respectively; at week 27, they were 40 IU/L (39; 40); 65% inhibition (34; 80) and 95% SRR (63; 187), respectively. Three serum samples from Ad-TSHR mice (38%) demonstrated dual TBAb/TSAb positivity. Conclusions: TBAb/TSAb were highly prevalent in Ad-TSHR-immunized mice, thus confirming the successful establishment of a novel, long-term murine model for GD. All TBAb- and TSAb-positive Ad-TSHR-immunized mice were TBII-positive. Thus, the binding immunoassay did not differentiate between TSHR-Ab functionality.

Cyclic peptides derived from some cylindrical loops of the leucine-rich repeat domain (LRD) of the thyrotropin receptor (TSHR) have been shown to treat disease manifestations in a mouse model of Graves' disease during a long-term protocol of four-weekly immunizations with adenovirus coding for the TSHR A-subunit (Ad-TSHR289). In a follow-up study, two additional cyclic peptides were tested, which were shortened in order to obtain additional information on the minimally involved epitopes and to enable easier production conditions. In addition, a linear peptide was tested, which mimics parts of three loops of the native TSHR LRD structure, and is potentially able to block the discontinuous epitopes of anti-TSHR antibodies. The novel peptides markedly reduced thyroid size, serum thyroxine levels, retro-orbital fibrosis, and tachycardia in Ad-TSHR289-immunized mice. In immunologically naïve mice, administration of the peptides did not induce any immune response. In summary, novel cyclic peptides mitigate many clinical findings in a mouse model of established Graves' disease and orbitopathy, and may therefore provide an additional therapeutic option compared to existing drugs or interventions.

BackgroundGPVI (Glycoprotein VI) is the essential platelet collagen receptor in atherothrombosis. Dimeric GPVI‐Fc (Revacept) binds to GPVI binding sites on plaque collagen. As expected, it did not increase bleeding in clinical studies. GPVI‐Fc is a potent inhibitor of atherosclerotic plaque‐induced platelet aggregation at high shear flow, but its inhibition at low shear flow is limited. We sought to increase the platelet inhibitory potential by fusing GPVI‐Fc to the ectonucleotidase CD39 (fusion protein GPVI‐CD39), which inhibits local ADP accumulation at vascular plaques, and thus to create a lesion‐directed dual antiplatelet therapy that is expected to lack systemic bleeding risks.Methods and ResultsGPVI‐CD39 effectively stimulated local ADP degradation and, compared with GPVI‐Fc alone, led to significantly increased inhibition of ADP‐, collagen‐, and human plaque–induced platelet aggregation in Multiplate aggregometry and plaque‐induced platelet thrombus formation under arterial flow conditions. GPVI‐CD39 did not increase bleeding time in an in vitro assay simulating primary hemostasis. In a mouse model of ferric chloride–induced arterial thrombosis, GPVI‐CD39 effectively delayed vascular thrombosis but did not increase tail bleeding time in vivo.ConclusionsGPVI‐CD39 is a novel approach to increase local antithrombotic activity at sites of atherosclerotic plaque rupture or injury. It enhances GPVI‐Fc–mediated platelet inhibition and presents a potentially effective and safe molecule for the treatment of acute atherothrombotic events, with a favorable risk–benefit ratio.

BackgroundGlycoprotein VI (GPVI) is the essential platelet collagen receptor in atherothrombosis, but its inhibition causes only a mild bleeding tendency. Thus, targeting this receptor has selective antithrombotic potential. ObjectivesThis study sought to compare compounds interfering with platelet GPVI–atherosclerotic plaque interaction to improve current antiatherothrombotic therapy. MethodsHuman atherosclerotic plaque–induced platelet aggregation was measured in anticoagulated blood under static and arterial flow conditions (550/s, 1,100/s, and 1,500/s). Inhibition by dimeric GPVI fragment crystallizable region of IgG (Fc) masking GPVI binding sites on collagen was compared with that of 3 anti-GPVI antibodies: BLO8-1, a human domain antibody; 5C4, a fragment antigen-binding (Fab fragment) of monoclonal rat immunoglobulin G; and m-Fab-F, a human recombinant sFab against GPVI dimers. ResultsGPVI-Fc reduced plaque-triggered platelet aggregation in static blood by 51%, BLO8-1 by 88%, and 5C4 by 93%. Under arterial flow conditions, BLO8-1 and 5C4 almost completely inhibited platelet aggregation while preserving platelet adhesion on plaque. Inhibition by GPVI-Fc, even at high concentrations, was less marked but increased with shear rate. Advanced optical imaging revealed rapid persistent GPVI-Fc binding to collagen under low and high shear flow, upstream and downstream of plaque fragments. At low shear particularly, platelets adhered in plaque flow niches to GPVI-Fc–free segments of collagen fibers and recruited other platelets onto aggregates via ADP and TxA2 release. ConclusionsAnti-GPVI antibodies inhibit atherosclerotic plaque-induced platelet aggregation under static and flow conditions more effectively than GPVI-Fc. However, potent platelet inhibition by GPVI-Fc at a higher shear rate (1,500/s) suggests localized antithrombotic efficacy at denuded or fissured stenotic high-risk lesions without systemic bleeding. The compound-specific differences have relevance for clinical trials targeting GPVI-collagen interaction combined with established antiplatelet therapies in patients with spontaneous plaque rupture or intervention-associated plaque injury.

A transient model for human Graves' disease was successfully established in mice using up to 3 immunizations with recombinant adenovirus expressing the extracellular A-subunit of the human TSH receptor (TSHR) (Ad-TSHR). We studied extension of adenovirally induced TSHR A-subunit immunization in mice by using a novel protocol of long-term 3- and 4-weekly injections. Generation of TSHR binding stimulatory antibodies (capacity to stimulate cAMP activity in TSHR-expressing test cells), goiter, and histological thyroid alterations were maintained for at least 9 months in all Ad-TSHR-immunized mice. In response to injection of 10(10) plaque-forming units of Ad-TSHR, also elevated mean serum T4 levels were observed throughout the study. Moreover, cardiac organ involvement (tachycardia and hypertrophy) were consistently observed in these mice. Higher doses of Ad-TSHR (10(11) plaque-forming units) did not produce consistent elevation of T4 and were not associated with a clear increase in heart rate vs controls, probably because these high doses provoked an immune response-induced tachycardia on their own. In summary, a long-term model of Graves' disease induced by a relatively simple protocol of continuing monthly immunizations should allow to investigate long-term disease mechanisms and may possibly obviate the need for more complicated disease models. Moreover, the clinical outcome predictor of tachycardia and cardiac involvement was reliably detected in the model.