Factor seven activating protease (FSAP) predicts response to intravenous thrombolysis in acute ischemic stroke

Factor VII Activating Protease (FSAP) and Its Importance in Hemostasis—Part I: FSAP Structure, Synthesis and Activity Regulation: A Narrative Review

Factor VII activating protease (FSAP) was first isolated from human plasma less than 30 years ago. Since then, many research groups have described the biological properties of this protease and its role in hemostasis and other processes in humans and other animals. With the progress of knowledge about the structure of FSAP, several of its relationships with other proteins or chemical compounds that may modulate its activity have been explained. These mutual axes are described in the present narrative review. The first part of our series of manuscripts on FSAP describes the structure of this protein and the processes leading to the enhancement and inhibition of its activities. The following parts, II and III, concern the role of FSAP in hemostasis and in the pathophysiology of human diseases, with particular emphasis on cardiovascular diseases.

Neurovascular Unit-Derived Extracellular Vesicles: From Their Physiopathological Roles to Their Clinical Applications in Acute Brain Injuries

Extracellular vesicles (EVs) form a heterogeneous group of membrane-enclosed structures secreted by all cell types. EVs export encapsulated materials composed of proteins, lipids, and nucleic acids, making them a key mediator in cell–cell communication. In the context of the neurovascular unit (NVU), a tightly interacting multicellular brain complex, EVs play a role in intercellular communication and in maintaining NVU functionality. In addition, NVU-derived EVs can also impact peripheral tissues by crossing the blood–brain barrier (BBB) to reach the blood stream. As such, EVs have been shown to be involved in the physiopathology of numerous neurological diseases. The presence of NVU-released EVs in the systemic circulation offers an opportunity to discover new diagnostic and prognostic markers for those diseases. This review outlines the most recent studies reporting the role of NVU-derived EVs in physiological and pathological mechanisms of the NVU, focusing on neuroinflammation and neurodegenerative diseases. Then, the clinical application of EVs-containing molecules as biomarkers in acute brain injuries, such as stroke and traumatic brain injuries (TBI), is discussed.

FSAP aggravated endothelial dysfunction and neurological deficits in acute ischemic stroke due to large vessel occlusion

Revascularization and angiogenesis, as substrates of sustained collateral circulation, play a crucial role in determining the severity and clinical outcome of acute ischemic stroke (AIS) due to large vessel occlusion (LVO). Developing an adjunct biomarker to help identify and monitor collateral status would aid stroke diagnosis and prognosis. To screen the potential biomarkers, proteomic analysis was performed in this study to identify those distinct plasma protein profiles in AIS due to LVO with different collateral status. Interestingly, we found that levels of Plasma Factor VII Activating Protease (FSAP) significantly increased in those AIS patients with poor collaterals, and were correlated with worse neurological outcome. Furtherly, both in vitro and in vivo models of ischemic stroke were used to explore pathological mechanisms of FSAP in endothelial dysfunction. We demonstrated that the FSAP inhibitor, high-molecular-weight hyaluronan (HMW-HA), enhanced the pro-angiogenic vascular factors, improved the integrity of brain blood barrier, and promoted newly formed cerebral microvessels in the ischemic penumbra, consequently improving neurological function. To elucidate the pathways that might contribute to revascularization during LVO, we applied transcriptomic analysis via unbiased RNA sequencing and showed that Wnt signaling was highly involved in FSAP mediated endothelial dysfunction. Notably, inhibition of Wnt5a largely reversed the protective effects from HMW-HA treatment, implying that FSAP might aggravate endothelial dysfunction and neurological deficits by regulating Wnt5a signaling. Therefore, FSAP may represent a potential biomarker for collateral status after LVO and a promising therapeutic target to be explored in the treatment of stroke.

Early Neurological Change After Ischemic Stroke Is Associated With 90-Day Outcome

BACKGROUND AND PURPOSE

Large-scale observational studies of acute ischemic stroke (AIS) promise to reveal mechanisms underlying cerebral ischemia. However, meaningful quantitative phenotypes attainable in large patient populations are needed. We characterize a dynamic metric of AIS instability, defined by change in National Institutes of Health Stroke Scale score (NIHSS) from baseline to 24 hours baseline to 24 hours (NIHSSbaseline - NIHSS24hours = ΔNIHSS6-24h), to examine its relevance to AIS mechanisms and long-term outcomes.

METHODS

Patients with NIHSS prospectively recorded within 6 hours after onset and then 24 hours later were enrolled in the GENISIS study (Genetics of Early Neurological Instability After Ischemic Stroke). Stepwise linear regression determined variables that independently influenced ΔNIHSS6-24h. In a subcohort of tPA (alteplase)-treated patients with large vessel occlusion, the influence of early sustained recanalization and hemorrhagic transformation on ΔNIHSS6-24h was examined. Finally, the association of ΔNIHSS6-24h with 90-day favorable outcomes (modified Rankin Scale score 0-2) was assessed. Independent analysis was performed using data from the 2 NINDS-tPA stroke trials (National Institute of Neurological Disorders and Stroke rt-PA).

RESULTS

For 2555 patients with AIS, median baseline NIHSS was 9 (interquartile range, 4-16), and median ΔNIHSS6-24h was 2 (interquartile range, 0-5). In a multivariable model, baseline NIHSS, tPA-treatment, age, glucose, site, and systolic blood pressure independently predicted ΔNIHSS6-24h (R2=0.15). In the large vessel occlusion subcohort, early sustained recanalization and hemorrhagic transformation increased the explained variance (R2=0.27), but much of the variance remained unexplained. ΔNIHSS6-24h had a significant and independent association with 90-day favorable outcome. For the subjects in the 2 NINDS-tPA trials, ΔNIHSS3-24h was similarly associated with 90-day outcomes.

CONCLUSIONS

The dynamic phenotype, ΔNIHSS6-24h, captures both explained and unexplained mechanisms involved in AIS and is significantly and independently associated with long-term outcomes. Thus, ΔNIHSS6-24h promises to be an easily obtainable and meaningful quantitative phenotype for large-scale genomic studies of AIS.

Factor VII Activating Protease Expression in Human Platelets and Accumulation in Symptomatic Carotid Plaque

Background

Factor VII activating protease (FSAP) is of interest as a marker for vascular inflammation and plaque destabilization. The aim of this study was to analyze the expression profile of FSAP in endarterectomy specimens that were taken from patients with asymptomatic and symptomatic carotid atherosclerotic plaques and to compare them with circulating FSAP levels.

Methods and Results

Plasma FSAP concentration, activity, and mRNA expression were measured in endarterectomy specimens and in monocytes and platelets. Plaque and plasma FSAP levels were higher in symptomatic patients (n=10) than in asymptomatic patients (n=14). Stronger FSAP immunostaining was observed in advanced symptomatic lesions, in intraplaque hemorrhage‐related structures, and in lipid‐rich areas within the necrotic core. FSAP was also colocalized with monocytes and macrophages (CD11b/CD68‐positive cells) and platelets (CD41‐positive cells) of the plaques. Moreover, human platelets expressed FSAP in vitro, at both the mRNA and protein levels. Expression is stimulated by thrombin receptor‐activating peptide and ADP and reduced by acetylsalicylic acid.

Conclusions

Plasma FSAP levels were significantly increased in patients with symptomatic carotid stenosis and thus may be involved in plaque development This plaque‐associated FSAP may be produced by platelets or macrophages or may be taken up from the circulation. To establish FSAP’s utility as a circulating or plaque biomarker in patients with symptomatic carotid atherosclerotic plaques, further studies are needed.

Prognostic Hemostasis Biomarkers in Acute Ischemic Stroke

Supplemental Digital Content is available in the text.

Objectives—

The prediction of patients at risk for poor clinical outcome after acute ischemic stroke remains challenging. An imbalance of coagulation factors may play an important role in progression and prognosis of these patients. In this systematic review, we assessed the current literature on hemostasis biomarkers and the association with poor clinical outcome in acute ischemic stroke.

Approach and Results—

A systematic search of Embase, Medline, Cochrane Library, Web of Science, and Google Scholar was performed on studies reporting on hemostasis biomarkers and clinical outcome after acute ischemic stroke. Studies were considered eligible if blood samples were collected within 72 hours after symptom onset. Additionally, clinical outcome should be assessed using a disability score (Barthel Index or modified Rankin scale). Methodological quality of included studies was assessed with an adapted version of the Quality Assessment of Diagnostic Accuracy Studies questionnaire. A total of 80 articles were read full text, and 41 studies were considered eligible for inclusion, reporting on 37 different hemostasis biomarkers. No single biomarker appeared to be effective in predicting poor clinical outcome in acute ischemic stroke patients.

Conclusions—

Based on current literature, no clear recommendations can be provided on which hemostasis biomarkers are a predictor of clinical outcome after acute ischemic stroke. However, some biomarkers show promising results and need to be further investigated and validated in large populations with clear defined study designs.

Markers of Coagulation and Fibrinolysis Predicting the Outcome of Acute Ischemic Stroke Thrombolysis Treatment: A Review of the Literature

Intravenous administration of recombinant tissue plasminogen activator (rt-PA) has been proven to be safe and effective in the treatment of acute ischemic stroke. Little is known, however, why this treatment is less effective in some patients while in others life-threatening side-effects, e.g., symptomatic intracerebral hemorrhage might occur. Clinical failure of thrombolysis related to absent or partial recanalization or reocclusion as well as hemorrhagic complications of thrombolysis are possibly related to hemostatic events. Data on markers of coagulation and/or fibrinolysis in acute stroke patients are numerous and may provide indications regarding therapy outcomes. Better understanding of the hemostatic and fibrinolytic system during rt-PA therapy might be clinically useful and ultimately might lead to an improvement in the efficacy or safety of this treatment. Studies on thrombus composition retrieved from cerebral arteries may also advance our knowledge and provide a key to improve acute stroke therapy. Here we provide a comprehensive review on a wide range of factors and markers of coagulation and fibrinolysis that have been studied in the context of thrombolysis outcome in ischemic stroke patients. Moreover, a brief summary is given on the most recent research on thrombus composition having a potential influence on outcomes.

Usefulness of ADAMTS13 to predict response to recanalization therapies in acute ischemic stroke

OBJECTIVE

We aimed to analyze ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) in relation to arterial recanalization in patients treated with IV tissue plasminogen activator (tPA) and in relation to futile recanalization in patients treated with mechanical thrombectomy.

METHODS

Acute ischemic stroke patients (n = 108) with documented arterial occlusions treated with IV-tPA were selected. ADAMTS13 activity was measured by ELISA in samples collected before treatment. Recanalization was assessed at 2 hours by transcranial Doppler. In 78 consecutive patients treated with endovascular thrombectomy, ADAMTS13 antigen was measured by ELISA and futile recanalization was defined as complete recanalization plus modified Rankin Scale score >2 at 3 months. Independent predictors of recanalization and futile recanalization were determined by logistic regression, adjusted by age, NIH Stroke Scale score, and time from stroke onset.

RESULTS

Patients who achieved tPA-induced recanalization had higher baseline ADAMTS13 activity (78.1% [68%-88%] vs 70.1% [61%-79%], p = 0.021). In logistic regression analysis, ADAMTS13 activity >75% was an independent predictor of recanalization (odds ratio = 6.76 [1.52-30.02], p = 0.012), together with absence of early ischemic signs and Oxfordshire Community Stroke Project classification. Regarding endovascular therapies, a reduced ADAMTS13 concentration (<982 ng/mL) was an independent predictor of futile recanalization (odds ratio = 67.4 [1.4-3,282.1], p = 0.034), together with age and diabetes mellitus. The addition of ADAMTS13 to clinical predictors of tPA-induced recanalization and futile recanalization improved discrimination and reclassification (integrated discrimination improvement = 10.06% and 28.4%, net reclassification improvement = 61.0% and 107.4%, respectively).

CONCLUSIONS

A reduced ADAMTS13 was associated with poor response to recanalization therapies. If confirmed in future prospective studies, a panel of blood biomarkers including ADAMTS13 might be a useful tool to guide reperfusion therapies.

Verification of a proteomic biomarker panel to diagnose minor stroke and transient ischaemic attack: phase 1 of SpecTRA, a large scale translational study

OBJECTIVE

To derive a plasma biomarker protein panel from a list of 141 candidate proteins which can differentiate transient ischaemic attack (TIA)/minor stroke from non-cerebrovascular (mimic) conditions in emergency department (ED) settings.

DESIGN

Prospective clinical study (#NCT03050099) with up to three timed blood draws no more than 36 h following symptom onset. Plasma samples analysed by multiple reaction monitoring-mass spectrometry (MRM-MS).

PARTICIPANTS

Totally 545 participants suspected of TIA enrolled in the EDs of two urban medical centres.

OUTCOMES

90-day, neurologist-adjudicated diagnosis of TIA informed by clinical and radiological investigations.

RESULTS

The final protein panel consists of 16 proteins whose patterns show differential abundance between TIA and mimic patients. Nine of the proteins were significant univariate predictors of TIA [odds ratio (95% confidence interval)]: L-selectin [0.726 (0.596-0.883)]; Insulin-like growth factor-binding protein 3 [0.727 (0.594-0.889)]; Coagulation factor X [0.740 (0.603-0.908)]; Serum paraoxonase/lactonase 3 [0.763 (0.630-0.924)]; Thrombospondin-1 [1.313 (1.081-1.595)]; Hyaluronan-binding protein 2 [0.776 (0.637-0.945)]; Heparin cofactor 2 [0.775 (0.634-0.947)]; Apolipoprotein B-100 [1.249 (1.037-1.503)]; and von Willebrand factor [1.256 (1.034-1.527)]. The scientific plausibility of the panel proteins is discussed.

CONCLUSIONS

Our panel has the potential to assist ED physicians in distinguishing TIA from mimic patients.