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Introduction: United States stroke systems are increasingly transitioning from alteplase (TPA) to tenecteplase (TNK). Real-world data on the safety and effectiveness of replacing TPA with TNK before large vessel occlusion (LVO) stroke endovascular treatment (EVT) are lacking. Methods: Four Pennsylvania stroke systems transitioned from TPA to TNK during the study period 01/2020–06/2023. LVO stroke patients who received intravenous thrombolysis with TPA or TNK before EVT were reviewed. Multivariate logistic analysis was conducted adjusting for age, sex, National Institute of Health Stroke Scale (NIHSS), occlusion site, last-known-well-to-intravenous thrombolysis time, interhospital-transfer and stroke system. Results: Of 635 patients, 309 (48.7%) received TNK and 326 (51.3%) TPA prior to EVT. The site of occlusion was the M1 middle cerebral artery (MCA) (47.7%), M2 MCA (25.4%), internal carotid artery (14.0%), tandem carotid with M1 or M2 MCA (9.8%) and basilar artery (3.1%). A favorable functional outcome (90-day mRS ≤ 2) was observed in 47.6% of TNK and 49.7% of TPA patients (p = 0.132). TNK versus TPA groups had similar rates of early recanalization (11.9% vs. 8.4%, p = 0.259), successful endovascular reperfusion (93.5% vs. 89.3%, p = 0.627), symptomatic intracranial hemorrhage (3.2% vs. 3.4%, p = 0.218) and 90-day all-cause mortality (23.1% vs. 21.5%, p = 0.491). Conclusions: This U.S. multicenter real-world clinical experience demonstrated that switching from TPA to TNK before EVT for LVO stroke resulted in similar endovascular reperfusion, safety, and functional outcomes. [ABSTRACT FROM AUTHOR]

Objective: Primary immune thrombocytopenia (ITP) paradoxically carries a high risk of developing thrombosis. However, the efficacy of mechanical thrombectomy (MT) for acute ischemic stroke (AIS) in ITP patients remains unclear due to its rarity. Case presentation: A 47-year-old female treated for chronic ITP for 2 years was admitted to the hematology department with severe thrombocytopenia. The patient was started on glucocorticoid therapy, and her platelet count rose soon. On sixth day of hospitalization, she suddenly presented with loss of consciousness, conjugate eye deviation to the left, and left hemiplegia. Magnetic resonance imaging and angiography showed an acute ischemic lesion with the left M1 occlusion. Emergent MT was performed and resulted in successful recanalization. Postoperatively, she recovered consciousness and was able to follow instructions. However, on the third day after MT, the patient suffered hemorrhagic infarction and brain herniation, and decompression craniectomy was performed. Her consciousness slowly recovered, and cranioplasty was performed after brain swelling improved. The patient was transferred to a rehabilitation hospital with modified Rankin Scale (mRS) 4 on 84th day of hospitalization, and eventually improved to mRS 3 with motor aphasia and right hemiparesis. Conclusion: MT may be effective for AIS in ITP patients with appropriate case selection.

Abstract Global fibrinolysis assays detect the fibrinolysis time of clot dissolution using tissue-type plasminogen activator (tPA). Two such assays, clot-fibrinolysis waveform analysis (CFWA) and global fibrinolysis capacity (GFC) assay, were recently developed. These were compared with rotational thromboelastography (ROTEM). Healthy donor blood samples were divided into four groups based on tPA-spiked concentrations: 0, 100, 500, and 1000 ng/mL. CFWA and GFC fibrinolysis times, including 4.1 µg/mL and 100 ng/mL tPA in the assays, were determined, denoted as CFWA-Lys and GFC-Lys, respectively. Statistical differences were recognized between tPA concentrations of 0 and 500/1000 ng/mL for CFWA-Lys, and 0 and 100/500/1000 ng/mL for GFC-Lys. The correlation coefficients with lysis onset time (LOT) of extrinsic pathway evaluation and intrinsic pathway evaluation in ROTEM were statistically significant at 0.610 and 0.590 for CFWA-Lys, and 0.939 and 0.928 for GFC-Lys, respectively (p-values

Global fibrinolysis assays detect the fibrinolysis time of clot dissolution using tissue-type plasminogen activator (tPA). Two such assays, clot-fibrinolysis waveform analysis (CFWA) and global fibrinolysis capacity (GFC) assay, were recently developed. These were compared with rotational thromboelastography (ROTEM). Healthy donor blood samples were divided into four groups based on tPA-spiked concentrations: 0, 100, 500, and 1000 ng/mL. CFWA and GFC fibrinolysis times, including 4.1 µg/mL and 100 ng/mL tPA in the assays, were determined, denoted as CFWA-Lys and GFC-Lys, respectively. Statistical differences were recognized between tPA concentrations of 0 and 500/1000 ng/mL for CFWA-Lys, and 0 and 100/500/1000 ng/mL for GFC-Lys. The correlation coefficients with lysis onset time (LOT) of extrinsic pathway evaluation and intrinsic pathway evaluation in ROTEM were statistically significant at 0.610 and 0.590 for CFWA-Lys, and 0.939 and 0.928 for GFC-Lys, respectively (p-values < 0.0001 for all correlations). Both assays showed significant correlations with ROTEM; however, the GFC assay proved to have better agreement with ROTEM compared with the CFWA assay. These assays have the potential to reflect a hyperfibrinolysis status with high tPA concentrations. [ABSTRACT FROM AUTHOR]

Plasminogen activator inhibitor‐1 (PAI‐1) impedes brain plasmin synthesis. Reduced plasmin activity facilitates cumulation of amyloid beta (Aβ) in Alzheimer's disease (AD). Since plasmin also regulates the synaptic activity, it is possible that altered PAI‐1 is present in other neurodegenerative disorders. We investigated whether PAI‐1 and its counter‐regulatory tissue plasminogen activator (tPA) are altered in serum of patients with dementia due to frontotemporal lobar degeneration (FTLD). Thirty five FTLD patients (21 in mild cognitive impairment stage (MCI) and 14 in dementia stage) and 10 cognitively healthy controls were recruited. Serum tPA and PAI‐1 protein levels were measured by anova. Correlation between biochemical and demographic data were explored by measuring Pearson correlation coefficient. Serum PAI‐1 levels were elevated in the FTLD dementia group as compared to FTLD MCI and controls. tPA serum levels and PAI‐1/tPA ratio did not significantly differ among groups. There was a negative correlation between PAI‐1 serum levels and disease severity measured by MMSE score. No correlations of tPA serum levels and PAI‐1/tPA ratio with MMSE were found. Increased PAI‐1 serum levels may serve as a marker of dementia in FTLD, suggesting that, besides Aβ pathway, the plasmin system may affect cognition through synaptic activity. [ABSTRACT FROM AUTHOR]

Abstract l-Palmitoylcarnitine (L-PC) is an important endogenous fatty acid metabolite. Its classical biological functions are involved in the regulations of membrane molecular dynamics and the β-oxidation of fatty acids. Decreased plasma long-chain acylcarnitines showed the association of venous thrombosis, implying anticoagulant activity of the metabolites and inspiring us to investigate if and how L-PC, a long-chain acylcarnitine, takes part in coagulation. Here we show that L-PC exerted anti-coagulant effects by potentiating the enzymatic activities of plasmin and tissue plasminogen activator (tPA). L-PC directly interacts with plasmin and tPA with an equilibrium dissociation constant (KD) of 6.47 × 10–9 and 4.46 × 10–9 M, respectively, showing high affinities. In mouse model, L-PC administration significantly inhibited FeCl3-induced arterial thrombosis. It also mitigated intracerebral thrombosis and inflammation in a transient middle cerebral artery occlusion (tMCAO) mouse model. L-PC induced little bleeding complications. The results show that L-PC has anti-thrombotic function by potentiating plasmin and tPA. Graphical Abstract

Elucidating the pathogenic mechanisms of Alzheimer's disease (AD) to identify therapeutic targets has been the focus of many decades of research. While deposition of extracellular amyloid-beta plaques and intraneuronal neurofibrillary tangles of hyperphosphorylated tau have historically been the two characteristic hallmarks of AD pathology, therapeutic strategies targeting these proteinopathies have not been successful in the clinics. Neuroinflammation has been gaining more attention as a therapeutic target because increasing evidence implicates neuroinflammation as a key factor in the early onset of AD disease progression. The peripheral immune response has emerged as an important contributor to the chronic neuroinflammation associated with AD pathophysiology. In this context, the plasminogen activator system (PAS), also referred to as the vasculature's fibrinolytic system, is emerging as a potential factor in AD pathogenesis. Evolving evidence suggests that the PAS plays a role in linking chronic peripheral inflammatory conditions to neuroinflammation in the brain. While the PAS is better known for its peripheral functions, components of the PAS are expressed in the brain and have been demonstrated to alter neuroinflammation and blood-brain barrier (BBB) permeation. Here, we review plasmin-dependent and -independent mechanisms by which the PAS modulates the BBB in AD pathogenesis and discuss therapeutic implications of these observations.

l-Palmitoylcarnitine (L-PC) is an important endogenous fatty acid metabolite. Its classical biological functions are involved in the regulations of membrane molecular dynamics and the β-oxidation of fatty acids. Decreased plasma long-chain acylcarnitines showed the association of venous thrombosis, implying anticoagulant activity of the metabolites and inspiring us to investigate if and how L-PC, a long-chain acylcarnitine, takes part in coagulation. Here we show that L-PC exerted anti-coagulant effects by potentiating the enzymatic activities of plasmin and tissue plasminogen activator (tPA). L-PC directly interacts with plasmin and tPA with an equilibrium dissociation constant (KD) of 6.47 × 10–9 and 4.46 × 10–9 M, respectively, showing high affinities. In mouse model, L-PC administration significantly inhibited FeCl3-induced arterial thrombosis. It also mitigated intracerebral thrombosis and inflammation in a transient middle cerebral artery occlusion (tMCAO) mouse model. L-PC induced little bleeding complications. The results show that L-PC has anti-thrombotic function by potentiating plasmin and tPA. [ABSTRACT FROM AUTHOR]

[Display omitted] Tissue-type plasminogen activator (tPA) is the gold standard for emergency treatment of ischemic stroke, which is the third leading cause of death worldwide. Major challenges of tPA therapy are its rapid elimination by plasminogen activator inhibitor-1 (PAI-1) and hepatic clearance, leading to the use of high doses and consequent serious side effects, including internal bleeding, swelling and low blood pressure. In this regard, we developed three polyethylene glycol (PEG)ylated tPA bioconjugates based on the recombinant human tPA drug Alteplase using site-specific conjugation strategies. The first bioconjugate with PEGylation at the N-terminus of tPA performed by reductive alkylation showed a reduced proteolytic activity of 68 % compared to wild type tPA. PEGylation at the single-free cysteine of tPA with linear and branched PEG revealed similar proteolytic activities as the wild-type protein. Moreover, both bioconjugates with PEG-cysteine-modification showed 2-fold slower inhibition kinetics by PAI-1. All bioconjugates increased in hydrodynamic size as a critical requirement for half-life extension. [ABSTRACT FROM AUTHOR]

Tissue‐type plasminogen activator (tPA) encoded by PLAT is a major mediator that promotes fibrinolysis and prevents thrombosis. Pathogenetic mutations in PLAT associated with venous thromboembolism have rarely been reported. Here, we report the first case of a homozygous point mutation c.1411T>C (p.Y471H) in PLAT leading to thromboembolic events and conduct related functional studies. The corresponding tPA mutant protein (tPA‐Y471H) and wild‐type tPA (tPA‐WT) were synthesized in vitro, and mutant mice (PLATH/H mice) were constructed. The molecular docking and surface plasmon resonance results indicated that the mutation impeded the hydrogen‐bonding interactions between the protease domain of tPA and the kringle 4 domain of plasminogen, and the binding affinity of tPA and plasminogen was significantly reduced with a difference of one order of magnitude. mRNA half‐life assay showed that the half‐life of tPA‐Y471H was shortened. The inferior vena cava thrombosis model showed that the rate of venous thrombosis in PLATH/H mice was 80% compared with 53% in wild‐type mice. Our data suggested a novel role for the protease domain of tPA in efficient plasminogen activation, and demonstrated that this tPA mutation could reduce the fibrinolysis function of the body and lead to an increased propensity for thrombosis. [ABSTRACT FROM AUTHOR]

Background: The influence of a magnetic field on the activation of bone cells and remodelling of alveolar bone is known to incite bone regeneration. Guided Bone Regeneration (GBR) aims to develop biomimetic scaffolds to allow for the functioning of the barrier and the precise succession of wound healing steps, including haemostasis. The effect of a magnetic field on blood clot dissolution has not been studied yet. Methods: We conducted a methodological study on the clot stability in the presence of a static magnetic field (SMF). Preformed whole blood (WB) clots were treated with either a broad proteolytic enzyme (trypsin) or a specific fibrinolytic agent, i.e., tissue-type plasminogen activator (t-PA). MG63 osteoblast-like cells were added to preformed WB clots to assess cell proliferation. Results: After having experienced a number of clotting and dissolution protocols, we obtained clot stability exerted by SMF when tissue factor (for clotting) and t-PA + plasminogen (for fibrinolysis) were used. WB clots allowed osteoblast-like cells to survive and proliferate, however no obvious effects of the magnetic field were noted. Conclusions: Paramagnetic properties of erythrocytes may have influenced the reduction in clot dissolution. Future studies are warranted to fully exploit the combination of magnetic forces, WB clot and cells in GBR applied to orthodontics and prosthodontics. [ABSTRACT FROM AUTHOR]

Abstract Tissue‐type plasminogen activator (tPA) encoded by PLAT is a major mediator that promotes fibrinolysis and prevents thrombosis. Pathogenetic mutations in PLAT associated with venous thromboembolism have rarely been reported. Here, we report the first case of a homozygous point mutation c.1411T>C (p.Y471H) in PLAT leading to thromboembolic events and conduct related functional studies. The corresponding tPA mutant protein (tPA‐Y471H) and wild‐type tPA (tPA‐WT) were synthesized in vitro, and mutant mice (PLATH/H mice) were constructed. The molecular docking and surface plasmon resonance results indicated that the mutation impeded the hydrogen‐bonding interactions between the protease domain of tPA and the kringle 4 domain of plasminogen, and the binding affinity of tPA and plasminogen was significantly reduced with a difference of one order of magnitude. mRNA half‐life assay showed that the half‐life of tPA‐Y471H was shortened. The inferior vena cava thrombosis model showed that the rate of venous thrombosis in PLATH/H mice was 80% compared with 53% in wild‐type mice. Our data suggested a novel role for the protease domain of tPA in efficient plasminogen activation, and demonstrated that this tPA mutation could reduce the fibrinolysis function of the body and lead to an increased propensity for thrombosis.

The major proteases that constitute the fibrinolysis system are tightly regulated. Protease inhibitors target plasmin, the protease responsible for fibrin degradation, and the proteases that convert plasminogen into plasmin, including tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). A second mechanism by which fibrinolysis is regulated involves exosite interactions, which localize plasminogen and its activators to fibrin, extracellular matrix (ECM) proteins, and cell surfaces. Once plasmin is generated in association with cell surfaces, it may cleave transmembrane proteins, activate growth factors, release growth factors from ECM proteins, remodel ECM, activate metalloproteases, and trigger cell-signaling by cleaving receptors in the Proteaseactivated Receptor (PAR) family. These processes are all implicated in cancer. It is thus not surprising that a family of structurally diverse but functionally similar cell-surface proteins, called Plasminogen Receptors (PlgRs), which increase the catalytic efficiency of plasminogen activation, have received attention for their possible function in cancer and as targets for anticancer drug development. In this review, we consider four previously described PlgRs, including: α-enolase, annexin-A2, Plg-RKT, and cytokeratin-8, in human cancer. To compare the PlgRs, we mined transcriptome profiling data from The Cancer Genome Atlas (TCGA) and searched for correlations between PlgR expression and patient survival. In glioma, the expression of specific PlgRs correlates with tumor grade. In a number of malignancies, including glioblastoma and liver cancer, increased expression of α-enolase or annexin-A2 is associated with an unfavorable prognosis. Whether these correlations reflect the function of PlgRs as receptors for plasminogen or other activities is discussed.

BACKGROUND:Astrocytes contribute to the crosstalk that generates chronic neuro-inflammation in neurological diseases; however, compared with microglia, astrocytes respond to a more limited continuum of innate immune system stimulants. Recent studies suggest that the fibrinolysis system may regulate inflammation. The goal of this study was to test whether fibrinolysis system components activate astrocytes and if so, elucidate the responsible biochemical pathway. METHODS:Primary cultures of astrocytes and microglia were prepared from neonatal mouse brains. The ability of purified fibrinolysis system proteins to elicit a pro-inflammatory response was determined by measuring expression of the mRNAs encoding tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and chemokine (C-C motif) ligand 2 (CCL2). IκBα phosphorylation also was measured. Plasminogen activation in association with cells was detected by chromogenic substrate hydrolysis. The activity of specific receptors was tested using neutralizing antibodies and reagents. RESULTS:Astrocytes expressed pro-inflammatory cytokines when treated with plasminogen but not when treated with agonists for Toll-like Receptor-4 (TLR4), TLR2, or TLR9. Microglia also expressed pro-inflammatory cytokines in response to plasminogen; however, in these cells, the response was observed only when tissue-type plasminogen activator (tPA) was added to activate plasminogen. In astrocytes, endogenously produced urokinase-type plasminogen activator (uPA) converted plasminogen into plasmin in the absence of tPA. Plasminogen activation was dependent on the plasminogen receptor, α-enolase, and the uPA receptor, uPAR. Although uPAR is capable of directly activating cell-signaling, the receptor responsible for cytokine expression and IκBα phosphorylation response to plasmin was Protease-activated Receptor-1 (PAR-1). The pathway, by which plasminogen induced astrocyte activation, was blocked by inhibiting any one of the three receptors implicated in this pathway with reagents such as εACA, α-enolase-specific antibody, uPAR-specific antibody, the uPA amino terminal fragment, or a pharmacologic PAR-1 inhibitor. CONCLUSIONS:Plasminogen may activate astrocytes for pro-inflammatory cytokine expression through the concerted action of at least three distinct fibrinolysis protease receptors. The pathway is dependent on uPA to activate plasminogen, which is expressed endogenously by astrocytes in culture but also may be provided by other cells in the astrocytic cell microenvironment in the CNS.

Background and Purpose- Acute ischemic stroke patients with history of prior ischemic stroke plus concomitant diabetes mellitus (DM) were excluded from the ECASS III trial (European Cooperative Acute Stroke Study) because of safety concerns. However, there are few data on use of intravenous tissue-type plasminogen activator and symptomatic intracerebral hemorrhage or outcomes in this population. Methods- Using data from the Get With The Guidelines-Stroke Registry between February 2009 and September 2017 (n=1619 hospitals), we examined characteristics and outcomes among patients with acute ischemic stroke treated with tissue-type plasminogen activator within the 3- to 4.5-hour window who had a history of stroke plus diabetes mellitus (HxS+DM) (n=2129) versus those without either history (n=16 690). Results- Compared with patients without either history, those with both prior stroke and DM treated with tissue-type plasminogen activator after an acute ischemic stroke had a higher prevalence of cardiovascular risk factors in addition to history of stroke, DM, and more severe stroke (National Institutes of Health Stroke Scale: median, 8 [interquartile range, 5-15] versus 7 [4-13]). The unadjusted rates of symptomatic intracerebral hemorrhage and in-hospital mortality were 4.3% (HxS+DM) versus 3.8% (without either history; P=0.31) and 6.2% versus 5.5% ( P=0.20), respectively. These differences were not statistically significant after risk adjustment (symptomatic intracerebral hemorrhage: adjusted odds ratio, 0.79 [95% CI, 0.51-1.21]; P=0.28; in-hospital mortality: odds ratio, 0.77 [95% CI, 0.52-1.14]; P=0.19). Unadjusted rate of functional independence (modified Rankin Scale score, 0-2) at discharge was lower in those with HxS+DM (30.9% HxS+DM versus 44.8% without either history; P≤0.0001), and this difference persisted after adjusting for baseline clinical factors (adjusted odds ratio, 0.76 [95% CI, 0.59-0.99]; P=0.04). Conclusions- Among patients with acute ischemic stroke treated with intravenous tissue-type plasminogen activator within the 3- to 4.5-hour window, HxS+DM was not associated with statistically significant increased symptomatic intracerebral hemorrhage or mortality risk.

Tissue-type plasminogen activator (tPA) activates fibrinolysis and also suppresses innate immune system responses to LPS in bone marrow-derived macrophages (BMDMs) and in vivo in mice. The objective of this study was to assess the activity of tPA as a regulator of macrophage physiology in the presence of plasmin. Enzymatically active and enzymatically inactive (EI) tPA appeared to comprehensively block the response to LPS in BMDMs, including expression of proinflammatory cytokines such as TNF-α and IL-1β and anti-inflammatory cytokines such as IL-10 and IL-1 receptor antagonist. The activity of EI-tPA as an LPS response modifier was conserved in the presence of plasminogen. By contrast, in BMDMs treated with tPA and plasminogen or preactivated plasmin, in the presence or absence of LPS, increased proinflammatory cytokine expression was observed and tPA failed to reverse the response. Plasmin independently activated NF-κB, ERK1/2, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase in BMDMs, which is characteristic of proinflammatory stimuli. Plasmin-induced cytokine expression was blocked by ε-aminocaproic acid, aprotinin, and inhibitors of the known plasmin substrate, Protease-activated receptor-1 (PAR-1), but not by N-methyl-d-aspartate receptor inhibitor, which blocks the effects of tPA on macrophages. Cytokine expression by BMDMs treated with the PAR-1 agonist, TFLLR, was not inhibited by EI-tPA, possibly explaining why EI-tPA does not inhibit macrophage responses to plasmin and providing evidence for specificity in the ability of tPA to oppose proinflammatory stimuli. Regulation of innate immunity by the fibrinolysis system may reflect the nature of the stimulus and a balance between the potentially opposing activities of tPA and plasmin.

Abstract Background In the vascular compartment, the serine protease tissue-type plasminogen activator (tPA) promotes fibrinolysis, justifying its clinical use against vasculo-occlusive diseases. Accumulating evidence shows that circulating tPA (endogenous or exogenous) also controls brain physiopathological processes, like cerebrovascular reactivity, blood–brain barrier (BBB) homeostasis, inflammation and neuronal fate. Whether this occurs by direct actions on parenchymal cells and/or indirectly via barriers between the blood and the central nervous system (CNS) remains unclear. Here, we postulated that vascular tPA can reach the brain parenchyma via the blood-cerebrospinal fluid barrier (BCSFB), that relies on choroid plexus (CP) epithelial cells (CPECs). Methods We produced various reporter fusion proteins to track tPA in primary cultures of CPECs, in CP explants and in vivo in mice. We also investigated the mechanisms underlying tPA transport across the BCSFB, with pharmacological and molecular approaches. Results We first demonstrated that tPA can be internalized by CPECs in primary cultures and in ex vivo CPs explants. In vivo, tPA can also be internalized by CPECs both at their basal and apical sides. After intra-vascular administration, tPA can reach the cerebral spinal fluid (CSF) and the brain parenchyma. Further investigation allowed discovering that the transcytosis of tPA is mediated by Low-density-Lipoprotein Related Protein-1 (LRP1) expressed at the surface of CPECs and depends on the finger domain of tPA. Interestingly, albumin, which has a size comparable to that of tPA, does not normally cross the CPs, but switches to a transportable form when grafted to the finger domain of tPA. Conclusions These findings provide new insights on how vascular tPA can reach the brain parenchyma, and open therapeutic avenues for CNS disorders.

Abstract Background Perineuronal nets (PNNs) are specialized extracellular matrix structures mainly found around fast-spiking parvalbumin (FS-PV) interneurons. In the adult, their degradation alters FS-PV-driven functions, such as brain plasticity and memory, and altered PNN structures have been found in neurodevelopmental and central nervous system disorders such as Alzheimer’s disease, leading to interest in identifying targets able to modify or participate in PNN metabolism. The serine protease tissue-type plasminogen activator (tPA) plays multifaceted roles in brain pathophysiology. However, its cellular expression profile in the brain remains unclear and a possible role in matrix plasticity through PNN remodeling has never been investigated. Result By combining a GFP reporter approach, immunohistology, electrophysiology, and single-cell RT-PCR, we discovered that cortical FS-PV interneurons are a source of tPA in vivo. We found that mice specifically lacking tPA in FS-PV interneurons display denser PNNs in the somatosensory cortex, suggesting a role for tPA from FS-PV interneurons in PNN remodeling. In vitro analyses in primary cultures of mouse interneurons also showed that tPA converts plasminogen into active plasmin, which in turn, directly degrades aggrecan, a major structural chondroitin sulfate proteoglycan (CSPG) in PNNs. Conclusions We demonstrate that tPA released from FS-PV interneurons in the central nervous system reduces PNN density through CSPG degradation. The discovery of this tPA-dependent PNN remodeling opens interesting insights into the control of brain plasticity.

The significance of plasminogen activation during the tympanic membrane (TM) healing is known mainly from studies performed on knock-out mice. In the previous study, we reported activation of genes coding proteins of plasminogen activation and inhibition system in rat's TM perforation healing. The aim of the present study was the evaluation of protein products expressed by these genes and their tissue distribution using Western blotting and immunofluorescent method, respectively, during 10-day observation period after injury. Otomicroscopical and histological evaluation were employed to assess the healing process. The expression of urokinase plasminogen activator (uPA) and its receptor (uPAR) were significantly upregulated in the proliferation phase, with subsequent gradual attenuation during remodeling phase of healing process, when keratinocyte migration was weakening. The expression of plasminogen activator inhibitor type 1 (PAI-1) also showed the highest levels during the proliferation phase. The increase of tissue plasminogen activator (tPA) expression was observed during the whole observation period, with the highest activity during the remodeling phase. Immunofluorescence of these proteins was present mainly in migrating epithelium. Our study found that plasminogen activation (uPA, uPAR, tPA) and inhibitory (PAI-1) molecules form a well-structured regulatory system of the epithelial migration that is critical to the healing of TM after its perforation. [ABSTRACT FROM AUTHOR]

Purpose: Treatment of distal vessel occlusions causing incomplete reperfusion after mechanical thrombectomy (MT) is debated. We hypothesized that pretreatment with intravenous thrombolysis (IVT) may facilitate delayed reperfusion (DR) of residual vessel occlusions causing incomplete reperfusion after MT. Methods: Retrospective analysis of patients with incomplete reperfusion after MT, defined as extended thrombolysis in cerebral infarction (eTICI) 2a–2c, and available perfusion follow-up imaging at 24 ± 12 h after MT. DR was defined as absence of any perfusion deficit on time-sensitive perfusion maps, indicating the absence of any residual occlusion. The association of IVT with the occurrence of DR was evaluated using a logistic regression analysis adjusted for confounders. Sensitivity analyses based on IVT timing (time between IVT start and the occurrence incomplete reperfusion following MT) were performed. Results: In 368 included patients (median age 73.7 years, 51.1% female), DR occurred in 225 (61.1%). Atrial fibrillation, higher eTICI grade, better collateral status and longer intervention-to-follow-up time were all associated with DR. IVT did not show an association with the occurrence of DR (aOR 0.80, 95% CI 0.44–1.46, even in time-sensitive strata, aOR 2.28 [95% CI 0.65–9.23] and aOR 1.53 [95% CI 0.52–4.73] for IVT to incomplete reperfusion following MT timing <80 and <100 min, respectively). Conclusion: A DR occurred in 60% of patients with incomplete MT at ~24 h and did not seem to occur more often in patients receiving pretreatment IVT. Further research on potential associations of IVT and DR after MT is required. [ABSTRACT FROM AUTHOR]

Background Patients presenting to hospitals during non-weekday hours experience worse outcomes, often attributed to reduced staffing. The American Heart Association International Stroke Conference ( ISC ) is well attended by stroke clinicians. We sought to determine whether patients with acute ischemic stroke ( AIS ) admitted during the ISC receive less guideline-adherent care and experience worse outcomes. Methods and Results We performed a retrospective cohort study of US hospitals participating in Get With The Guidelines-Stroke and assessed use of intravenous tissue plasminogen activator, other quality measures, and outcomes for patients with AIS admitted during the ISC compared with those admitted the weeks before and after the conference. A total of 69 738 patients with AIS were included: mean age, 72 years; 52% women; 29% nonwhite. There was no difference between the average weekly number of AIS cases admitted during ISC weeks versus non- ISC weeks (1984 versus 1997; P=0.95). Patient and hospital characteristics were similar between ISC and non- ISC time periods. There were no significant differences in 14 quality metrics and 5 clinical outcomes between patients with AIS treated during the ISC versus non- ISC weeks. Patients with AIS who presented within 2 hours of onset had no difference in the likelihood of receiving intravenous tissue plasminogen activator within 3 hours (adjusted odds ratio, 0.89; 95% confidence interval, 0.77-1.03; P=0.13) or the likelihood of receiving intravenous tissue plasminogen activator within 60 minutes of arrival (adjusted odds ratio, 0.92; 95% confidence interval, 0.83-1.02; P=0.13). Conclusions Patients with acute stroke admitted to Get With The Guidelines-Stroke hospitals during ISC received the same quality care and had similar outcomes as patients admitted at other times.

The fibrinolysis proteinase tissue-type plasminogen activator (tPA, also known as PLAT) triggers cell signaling and regulates cell physiology. In PC12 cells, Schwann cells and macrophages, the N-methyl-D-aspartate receptor (NMDA-R) mediates tPA signaling. Plasminogen activator inhibitor-1 (PAI1, also known as SERPINE1) is a rapidly acting inhibitor of tPA enzyme activity. Although tPA-initiated cell signaling is not dependent on its enzyme active site, we show that tPA signaling is neutralized by PAI1. In PC12 cells, PAI1 blocked the ERK1/2 activation mediated by tPA as well as neurite outgrowth. In Schwann cells, PAI1 blocked tPA-mediated ERK1/2 activation and cell migration. In macrophages, PAI1 blocked the ability of tPA to inhibit IκBα phosphorylation and cytokine expression. The cell signaling activity of tPA-PAI1 complex was rescued when the complex was formed with PAI1R76E, which binds to LRP1 with decreased affinity, by pre-treating cells with the LRP1 antagonist receptor-associated protein and upon LRP1 gene silencing. The inhibitory role of LRP1 in tPA-PAI1 complex-initiated cell signaling was unanticipated given the reported role of LRP1 as an NMDA-R co-receptor in signaling responses elicited by free tPA or α2-macroglobulin. We conclude that PAI1 functions as an in-hibitor not only of the enzyme activity of tPA but also of tPA receptor-mediated activities.

Background: Dual antiplatelet therapy (DAPT) was noninferior to alteplase in minor nondisabling strokes in the ARAMIS trial (Antiplatelet Versus R-tPA for Acute Mild Ischemic Stroke); however, early neurological deterioration (END) associated with vessel stenosis may benefit from DAPT. We investigated whether the efficacy of DAPT was greater than alteplase in minor strokes with no large vessel occlusion (LVO)., Methods: This study was a prespecified post hoc analysis of the ARAMIS trial and included patients with responsible vessel examination in the as-treated analysis set of the ARAMIS trial who were divided into LVO group and non-LVO group. In each group, patients were further classified into DAPT and intravenous alteplase treatments. Primary outcome was END at 24 hours defined as more than or equal to 4-point National Institutes of Health Stroke Scale score increase compared with baseline, and safety outcomes were symptomatic intracerebral hemorrhage and bleeding events during study. The primary analysis was estimated with a risk difference calculated by a generalized linear model including adjusted different baseline characteristics between treatments., Results: Of 723 patients from the ARAMIS trial, 480 patients were included: 36 were categorized into LVO group and 444 into non-LVO group, of whom 20 patients had END. Compared with intravenous alteplase, a lower proportion of END was found after DAPT treatment in the non-LVO group (adjusted risk difference, -4.8% [95% CI, -6.9% to -2.6%]; P <0.001), but not in the LVO group (adjusted risk difference, 2.3% [95% CI, -17.6% to 22.3%]; P =0.82). The interaction was marginally significant between groups ( P =0.06). In the non-LVO group, a lower proportion of bleeding events was found after DAPT treatment than intravenous alteplase (adjusted risk difference, -6.4% [95% CI, -8.9% to -3.9%]; P <0.001). Other safety outcomes were similar between the 2 treatments., Conclusions: Among minor nondisabling acute ischemic stroke without LVO, DAPT may be superior to intravenous alteplase regarding preventing END with a better safety profile., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03661411., Competing Interests: None.

Objective: To establish a new mouse model of haemorrhagic transformation associated with delayed tissue-type plasminogen activator (tPA) treatment to provide a novel tool to study therapeutic strategies for haemorrhagic transformation. Methods: Male C57BL/6 mice were subjected to carotid artery thrombosis stimulated with ferric chloride. The thrombus was then mechanically detached to induce migration toward the intracranial circulation. To induce haemorrhagic transformation, mice were intravenously injected with 10 mg/kg tPA 4.5 h after the onset of ischaemia and were sacrificed 24 h after tPA treatment. Results: In this new model, administration of tPA 4.5 h after stroke exacerbated the risk of intracerebral haemorrhage. Thrombolysis with tPA also exacerbated cerebral infarction, brain oedema, blood–brain barrier breakdown, and neurological deficits. However, cerebral blood flow was not significantly affected. Conclusion: The present model is reproducible, easy to perform, and mimics the clinical situation of haemorrhagic transformation after tPA treatment in humans. This modified model can be used as a new tool to test experimental drugs for haemorrhagic transformation associated with delayed tPA administration after an ischaemic stroke.

Background: In the vascular compartment, the serine protease tissue-type plasminogen activator (tPA) promotes fibrinolysis, justifying its clinical use against vasculo-occlusive diseases. Accumulating evidence shows that circulating tPA (endogenous or exogenous) also controls brain physiopathological processes, like cerebrovascular reactivity, blood–brain barrier (BBB) homeostasis, inflammation and neuronal fate. Whether this occurs by direct actions on parenchymal cells and/or indirectly via barriers between the blood and the central nervous system (CNS) remains unclear. Here, we postulated that vascular tPA can reach the brain parenchyma via the blood-cerebrospinal fluid barrier (BCSFB), that relies on choroid plexus (CP) epithelial cells (CPECs). Methods: We produced various reporter fusion proteins to track tPA in primary cultures of CPECs, in CP explants and in vivo in mice. We also investigated the mechanisms underlying tPA transport across the BCSFB, with pharmacological and molecular approaches. Results: We first demonstrated that tPA can be internalized by CPECs in primary cultures and in ex vivo CPs explants. In vivo, tPA can also be internalized by CPECs both at their basal and apical sides. After intra-vascular administration, tPA can reach the cerebral spinal fluid (CSF) and the brain parenchyma. Further investigation allowed discovering that the transcytosis of tPA is mediated by Low-density-Lipoprotein Related Protein-1 (LRP1) expressed at the surface of CPECs and depends on the finger domain of tPA. Interestingly, albumin, which has a size comparable to that of tPA, does not normally cross the CPs, but switches to a transportable form when grafted to the finger domain of tPA. Conclusions: These findings provide new insights on how vascular tPA can reach the brain parenchyma, and open therapeutic avenues for CNS disorders. [ABSTRACT FROM AUTHOR]

Background: Perineuronal nets (PNNs) are specialized extracellular matrix structures mainly found around fast-spiking parvalbumin (FS-PV) interneurons. In the adult, their degradation alters FS-PV-driven functions, such as brain plasticity and memory, and altered PNN structures have been found in neurodevelopmental and central nervous system disorders such as Alzheimer's disease, leading to interest in identifying targets able to modify or participate in PNN metabolism. The serine protease tissue-type plasminogen activator (tPA) plays multifaceted roles in brain pathophysiology. However, its cellular expression profile in the brain remains unclear and a possible role in matrix plasticity through PNN remodeling has never been investigated. Result: By combining a GFP reporter approach, immunohistology, electrophysiology, and single-cell RT-PCR, we discovered that cortical FS-PV interneurons are a source of tPA in vivo. We found that mice specifically lacking tPA in FS-PV interneurons display denser PNNs in the somatosensory cortex, suggesting a role for tPA from FS-PV interneurons in PNN remodeling. In vitro analyses in primary cultures of mouse interneurons also showed that tPA converts plasminogen into active plasmin, which in turn, directly degrades aggrecan, a major structural chondroitin sulfate proteoglycan (CSPG) in PNNs. Conclusions: We demonstrate that tPA released from FS-PV interneurons in the central nervous system reduces PNN density through CSPG degradation. The discovery of this tPA-dependent PNN remodeling opens interesting insights into the control of brain plasticity. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a central nervous system (CNS) disease characterized by loss of memory, cognitive functions, and neurodegeneration. Plasmin is an enzyme degrading many plasma proteins. In the CNS, plasmin may reduce the accumulation of beta amyloid (Aβ) and have other actions relevant to AD pathophysiology. Brain plasmin synthesis is regulated by two enzymes: one activating, the tissue plasminogen activator (tPA), and the other inhibiting, the plasminogen activator inhibitor-1 (PAI-1). We investigated the levels of tPA and PAI-1 in serum from 40 AD and 40 amnestic mild cognitively impaired (aMCI) patients compared to 10 cognitively healthy controls. Moreover, we also examined the PAI-1/tPA ratio in these patient groups. Venous blood was collected and the PAI-1 and tPA serum concentrations were quantified using sandwich ELISAs. The results showed that PAI-1 levels increased in AD and aMCI patients. This increase negatively correlated with cognitive performance measured using the Mini-Mental Status Exam (MMSE). Similarly, the ratio between tPA and PAI-1 gradually increases in aMCI and AD patients. This study demonstrates that AD and aMCI patients have altered PAI-1 serum levels and PAI-1/tPA ratio. Since these enzymes are CNS regulators of plasmin, PAI-1 serum levels could be a marker reflecting cognitive decline in AD. [ABSTRACT FROM AUTHOR]

Intravenous tissue type plasminogen activator thrombolytic therapy has long been a mainstay in acute ischemic stroke therapy. However, patients receiving IV tPA therapy may have variable response with some subsets of patients having worsened outcomes. Diabetes mellitus, a clinically important and common vascular co-morbidity in AIS patients, can result in increased risk of hemorrhagic transformation after IV tPA therapy. In this short-review, we summarize the recent advances in understanding the mechanisms underlying the exacerbated HT after IV tPA therapy in AIS patients with DM. Potential precipitating factors including more severe blood–brain barrier disruption, enhanced oxidative stress, neuroinflammation and apoptosis, as well as several others contributors such as abnormal protein glycation, extracellular proteolytic dysfunction and impairment of collateral flow in DM are discussed. Additionally, several tPA combination approaches from experimental studies that may help to ameliorate the aggravation of post IV tPA-induced HT in AIS patients with DM are also briefly summarized. Urgently, more clinical and experimental studies aiming to better understand the mechanisms involved in DM-related exacerbation of HT after IV tPA therapy in AIS are needed for developing potential approaches protecting against this harmful complication in the management of AIS patients with DM.

Objective:To evaluate whether endovascular thrombectomy combined with intravenous thrombolysis is superior to the standard treatment of intravenous thrombolysis for the treatment of ischemic stroke.Methods:A meta-analysis of 12 studies obtained by searching PubMed and Web of Science database was performed to determine whether the difference in mortality (within 7 days or 90 days), functional outcome (modified Rankin Scale, 0-2), hemorrhage (symptomatic intracerebral hemorrhage, and subarachnoid hemorrhage), and recurrent ischemic stroke rate at 90 days between patients who underwent mechanical intravenous thrombolysis with (intervention) and without (control) endovascular thrombectomy.Results:As compared with the control group, patients in the intervention group had lower 90-day mortality [summary risk ratio (RR) = 0.83, 95% confidence interval (CI): 0.69-0.99; n = 1309/1070], higher recanalization rate (RR = 2.24, 95% CI: 1.97-2.56; n = 504/497), better functional outcome (modified Rankin score: 0-2; RR = 1.41, 95% CI: 1.29-1.54; n = 1702/1502), and higher rate of subarachnoid hemorrhage (RR = 2.40, 95% CI: 1.45-3.99; n = 1046/875) without significant difference in the 7-day mortality (RR = 1.12, 95% CI: 0.84-1.50; n = 951/773), symptomatic intracranial hemorrhage (RR = 1.12, 95% CI: 0.82-1.54; n = 1707/1507), or recurrent ischemic stroke (RR = 0.90, 95% CI: 0.52-1.54; n = 718/506).Conclusion:Our results demonstrated that patients in the intervention group had lower mortality and better functional outcomes than the control group. Although patients in the intervention group had a higher rate of subarachnoid hemorrhage; hence, endovascular thrombectomy combined with intravenous thrombolysis is still a beneficial intervention for a defined population of stroke patients.

Timely reperfusion is critical in acute ischemic stroke (AIS) and ST-segment-elevation myocardial infarction (STEMI). The degree to which hospital performance is correlated on emergent STEMI and AIS care is unknown. Primary objective of this study was to determine whether there was a positive correlation between hospital performance on door-to-balloon (D2B) time for STEMI and door-to-needle (DTN) time for AIS, with and without controlling for patient and hospital differences. Prospective study of all hospitals in both Get With The Guidelines-Stroke and Get With The Guidelines-Coronary Artery Disease from 2006 to 2009 and treating ≥10 patients. We compared hospital-level DTN time and D2B time using Spearman rank correlation coefficients and hierarchical linear regression modeling. There were 43 hospitals with 1976 AIS and 59 823 STEMI patients. Hospitals' DTN times for AIS did not correlate with D2B times for STEMI (ρ=-0.09; P=0.55). There was no correlation between hospitals' proportion of eligible patients treated within target time windows for AIS and STEMI (median DTN time

Background and purposeClinical trials have demonstrated improved 90-day outcomes for patients with acute ischemic stroke treated with stent retriever thrombectomy plus tissue-type plasminogen activator (SST+tPA) compared with tPA. Previous studies suggested that this strategy may be cost-effective, but models were derived from pooled data and older assumptions.MethodsIn this prospective economic substudy conducted alongside the SWIFT-PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke), in-trial costs were measured for patients using detailed medical resource utilization and hospital billing data. Utility weights were assessed at 30 and 90 days using the EuroQol-5 dimension questionnaire. Post-trial costs and life-expectancy were estimated for each surviving patient using a model based on trial data and inputs derived from a contemporary cohort of ischemic stroke survivors.ResultsIndex hospitalization costs were $17 183 per patient higher for SST+tPA than for tPA ($45 761 versus $28 578; P

Tenecteplase (TNK) has been shown to be noninferior to Alteplase (ALT) for long term efficacy and safety outcomes. Whether this also applies to short term efficacy outcomes such as early clinical improvement and recanalization is unknown. To compare TNK and ALT regarding the short term efficacy outcomes: early neurological improvement and recanalization. The PRISMA was used to conduct a meta analysis, adapted to noninferiority analysis. The primary outcome was early (24-72 h) neurological improvement, defined as either NIHSS score 0 or reduction of at least 8 points compared to baseline. Recanalization was a secondary outcome. The noninferiority margin was set at 6.5%. Search strategy yielded 5 randomized clinical trials (1585 patients: 828 TNK, 757 ALT). Mean age was 70.8, 58.8% were men, mean baseline NIHSS was 7, and mean onset to treatment time was 148 min. Patients in intervention group received TNK at doses of 0.1 mg/kg (6.8%), 0.25 mg/kg (24.6%), and 0.4 mg/kg (68.6%), while all ALT patients received 0.9 mg/kg. In random effects meta analysis, TNK was noninferior to ALT for the primary outcome, early major neurological improvement (risk difference 8% in favor of TNK, 95% CI 1%-15%). Recanalization was also noninferior for the TNK compared to the ALT group (risk difference 9% in favor of TNK, 95% CI 6% to 23%). Fixed effects models yielded similarly noninferior results and signaled for a possible TNK superiority for both early neurological improvement and recanalization. TNK is noninferior to ALT at the short term efficacy outcomes: early neurological improvement and recanalization. [ABSTRACT FROM AUTHOR]

Background: This study aims to assess the efficacy and safety of different doses of intravenous tissue-type plasminogen activator (tPA) for acute ischemic stroke (AIS) by adopting a network meta-analysis (NMA). Methods: Studies comparing different doses of tPA in AIS were identified by retrieving electronic databases. NMAs of outcome measures included favorable functional outcome with a modified Rankin scale score (mRS) of 0 or 1 at 3 months after treatment (3M-FF), the functional independence with a mRS of 0, 1, or 2 at 3 months (3M-FI), symptomatic intracranial hemorrhage (sICH) and 3-month all-cause mortality (3M-M). Symptomatic intracranial hemorrhage (sICH) and 3-month all-cause mortality (3M-M) were assessed. Probability-based ranking and surface under cumulative ranking (SUCRA) were performed to identify the best dose of tPA. Inconsistency was evaluated by node-splitting analysis and a loop-specific approach. Publication bias was analyzed by funnel plots. Results: A total of 14 studies were included in the quantitative synthesis. The NMA results revealed no difference among low (<0.7 mg/kg), moderate (0.8 mg/kg), and standard (0.9 mg/kg) doses of tPA with regard to efficacy and safety. The SUCRAs of 3M-FF and 3M-FI showed that the standard dose ranked first, the moderate dose ranked second, and the low dose ranked third. The SUCRA of sICH showed that the standard dose ranked first (78.1%), the low dose ranked second (61.0%), and the moderate dose ranked third (11.0%). The SUCRAs of 3-month mortality showed that the standard dose ranked first (73.2%), the moderate dose ranked second (40.8%), and the low dose ranked third (36.1%). No significant inconsistency was shown by node-splitting analysis and no publication bias was shown in funnel plots. Conclusion: Lower dose tPA was comparable to the standard dose with regard to efficacy and safety. Based on the SUCRA results and American Heart Association/American Stroke Association (AHA/ASA) guidelines, the standard dose was still the optimal selection for AIS. [ABSTRACT FROM AUTHOR]

BackgroundThis study aims to assess the efficacy and safety of different doses of intravenous tissue-type plasminogen activator (tPA) for acute ischemic stroke (AIS) by adopting a network meta-analysis (NMA).MethodsStudies comparing different doses of tPA in AIS were identified by retrieving electronic databases. NMAs of outcome measures included favorable functional outcome with a modified Rankin scale score (mRS) of 0 or 1 at 3 months after treatment (3M-FF), the functional independence with a mRS of 0, 1, or 2 at 3 months (3M-FI), symptomatic intracranial hemorrhage (sICH) and 3-month all-cause mortality (3M-M). Symptomatic intracranial hemorrhage (sICH) and 3-month all-cause mortality (3M-M) were assessed. Probability-based ranking and surface under cumulative ranking (SUCRA) were performed to identify the best dose of tPA. Inconsistency was evaluated by node-splitting analysis and a loop-specific approach. Publication bias was analyzed by funnel plots.ResultsA total of 14 studies were included in the quantitative synthesis. The NMA results revealed no difference among low (

Schwann cells (SCs) detect injury to peripheral nerves and transform phenotypically to respond to injury and facilitate repair. Cell-signaling pathways and changes in gene expression that drive SC phenotypic transformation in injury have been described; however, the SC receptors that detect peripheral nervous system (PNS) injury have not been identified. LDL receptor-related protein 1 (LRP1) is a receptor for numerous ligands, including intracellular proteins released by injured cells and protein components of degenerated myelin. In certain cell types, including SCs, LRP1 is a cell-signaling receptor. Here, we show that binding of the LRP1 ligand, tissue-type plasminogen activator (tPA), to cultured rat SCs induces c-Jun phosphorylation, a central event in activation of the SC repair program. The response to tPA was blocked by the LRP1 antagonist, receptor-associated protein. c-Jun phosphorylation was also observed when cultured rat SCs were treated with a recombinant derivative of matrix metalloproteinase-9 that contains the LRP1 recognition motif (PEX). The ability of LRP1 to induce c-Jun phosphorylation and ERK1/2 activation was confirmed using cultures of human SCs. When tPA or PEX was injected directly into crush-injured rat sciatic nerves, c-Jun phosphorylation and ERK1/2 activation were observed in SCs in vivo. The ability of LRP1 to bind proteins released in the earliest stages of PNS injury and to induce c-Jun phosphorylation support a model in which SC LRP1 functions as an injury-detection receptor in the PNS.

LDL receptor-related protein-1 (LRP1) is an endocytic and cell-signaling receptor. In mice in which LRP1 is deleted in myeloid cells, the response to lipopolysaccharide (LPS) was greatly exacerbated. LRP1 deletion in macrophages in vitro, under the control of tamoxifen-activated Cre-ER(T) fusion protein, robustly increased expression of proinflammatory cytokines and chemokines. In LRP1-expressing macrophages, proinflammatory mediator expression was regulated by LRP1 ligands in a ligand-specific manner. The LRP1 agonists, α2-macroglobulin and tissue-type plasminogen activator, attenuated expression of inflammatory mediators, even in the presence of LPS. The antagonists, receptor-associated protein (RAP) and lactoferrin (LF), and LRP1-specific antibody had the entirely opposite effect, promoting inflammatory mediator expression and mimicking LRP1 deletion. NFκB was rapidly activated in response to RAP and LF and responsible for the initial increase in expression of proinflammatory mediators. RAP and LF also significantly increased expression of microRNA-155 (miR-155) after a lag phase of about 4 h. miR-155 expression reflected, at least in part, activation of secondary cell-signaling pathways downstream of TNFα. Although miR-155 was not involved in the initial induction of cytokine expression in response to LRP1 antagonists, miR-155 was essential for sustaining the proinflammatory response. We conclude that LRP1, NFκB, and miR-155 function as members of a previously unidentified system that has the potential to inhibit or sustain inflammation, depending on the continuum of LRP1 ligands present in the macrophage microenvironment.

Dementia is a clinical syndrome that affects approximately 47 million people worldwide and is characterized by progressive and irreversible decline of cognitive, behavioral and sesorimotor functions. Alzheimer’s disease (AD) accounts for approximately 60–80% of all cases of dementia, and neuropathologically is characterized by extracellular deposits of insoluble amyloid-β (Aβ) and intracellular aggregates of hyperphosphorylated tau. Significantly, although for a long time it was believed that the extracellular accumulation of Aβ was the culprit of the symptoms observed in these patients, more recent studies have shown that cognitive decline in people suffering this disease is associated with soluble Aβ-induced synaptic dysfunction instead of the formation of insoluble Aβ-containing extracellular plaques. These observations are translationally relevant because soluble Aβ-induced synaptic dysfunction is an early event in AD that precedes neuronal death, and thus is amenable to therapeutic interventions to prevent cognitive decline before the progression to irreversible brain damage. The plasminogen activating (PA) system is an enzymatic cascade that triggers the degradation of fibrin by catalyzing the conversion of plasminogen into plasmin via two serine proteinases: tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). Experimental evidence reported over the last three decades has shown that tPA and uPA play a role in the pathogenesis of AD. However, these studies have focused on the ability of these plasminogen activators to trigger plasmin-induced cleavage of insoluble Aβ-containing extracellular plaques. In contrast, recent evidence indicates that activity-dependent release of uPA from the presynaptic terminal of cerebral cortical neurons protects the synapse from the deleterious effects of soluble Aβ via a mechanism that does not require plasmin generation or the cleavage of Aβ fibrils. Below we discuss the role of the PA system in the pathogenesis of AD and the translational relevance of data published to this date.

Ischemic tolerance is a phenomenon whereby transient exposure to a non-injurious preconditioning stimulus triggers resistance to a subsequent lethal ischemic insult. Despite the fact that not only neurons but also astrocytes and endothelial cells have a unique response to preconditioning stimuli, current research has been focused mostly on the effect of preconditioning on neuronal death. Thus, it is unclear if the blood-brain barrier (BBB) can be preconditioned independently of an effect on neuronal survival. The release of tissue-type plasminogen activator (tPA) from perivascular astrocytes in response to an ischemic insult increases the permeability of the BBB. In line with these observations, treatment with recombinant tPA increases the permeability of the BBB and genetic deficiency of tPA attenuates the development of post-ischemic edema. Here we show that tPA induces ischemic tolerance in the BBB independently of an effect on neuronal survival. We found that tPA renders the BBB resistant to an ischemic injury by inducing TNF-α-mediated astrocytic activation and increasing the abundance of aquaporin-4-immunoreactive astrocytic end-feet processes in the neurovascular unit. This is a new role for tPA, that does not require plasmin generation, and with potential therapeutic implications for patients with cerebrovascular disease. [ABSTRACT FROM AUTHOR]

Abstract Background The coronavirus disease 2019 (COVID‐19) pandemic has caused a large surge of acute respiratory distress syndrome (ARDS). Prior phase I trials (non–COVID‐19) demonstrated improvement in pulmonary function in patients ARDS using fibrinolytic therapy. A follow‐up trial using the widely available tissue‐type plasminogen activator (t‐PA) alteplase is now needed to assess optimal dosing and safety in this critically ill patient population. Objective To describe the design and rationale of a phase IIa trial to evaluate the safety and efficacy of alteplase treatment for moderate/severe COVID‐19–induced ARDS. Patients/Methods A rapidly adaptive, pragmatic, open‐label, randomized, controlled, phase IIa clinical trial will be conducted with 3 groups: intravenous alteplase 50 mg, intravenous alteplase 100 mg, and control (standard‐of‐care). Inclusion criteria are known/suspected COVID‐19 infection with PaO2/FiO2 ratio 4 hours despite maximal mechanical ventilation management. Alteplase will be delivered through an initial bolus of 50 mg or 100 mg followed by heparin infusion for systemic anticoagulation, with alteplase redosing if there is a >20% PaO2/FiO2 improvement not sustained by 24 hours. Results The primary outcome is improvement in PaO2/FiO2 at 48 hours after randomization. Other outcomes include ventilator‐ and intensive care unit–free days, successful extubation (no reintubation ≤3 days after initial extubation), and mortality. Fifty eligible patients will be enrolled in a rapidly adaptive, modified stepped‐wedge design with 4 looks at the data. Conclusion Findings will provide timely information on the safety, efficacy, and optimal dosing of t‐PA to treat moderate/severe COVID‐19–induced ARDS, which can be rapidly adapted to a phase III trial (NCT04357730; FDA IND 149634).

ObjectiveIn this study, we retrospectively analyzed 795 AIS patients who received intravenous alteplase for thrombolytic therapy in one third-class hospital or three second-class hospitals in Dongyang City and sought to evaluate the effects of the medical community model on intravenous alteplase door-to-needle time (DNT) and prognosis of patients with acute ischemic stroke.MethodsAccording to whether the medical community model is established or not, 303 AIS patients (204 cases from the third-class hospital and 99 cases from three second-class hospitals) were assigned to control group unavailable to the medical community model and 492 AIS patients (297 cases from the third-class hospital, and 195 cases from three second-class hospitals) into observational group available to the medical community model.ResultsA higher thrombolysis rate, a shorter DNT, more patients with DNT ≤ 60 min and DNT ≤ 45 min, a shorter ONT, lower National Institutes of Health Stroke Scale (NIHSS) scores at 24 h, 7 d, 14 d, and modified Rankin scale (mRS) scores at 3 months after thrombolytic therapy, a shorter length of hospital stay, and less hospitalization expense were found in the observational group than the control group. Subgroup analysis based on different-class hospitals revealed that the medical community model could reduce the DNT and ONT to increase the thrombolysis rate of AIS patients, especially in low-class hospitals. After the establishment of the medical community model, the AIS patients whether from the third-class hospital or three second-class hospitals exhibited lower NIHSS scores at 24 h, 7 d, 14 d after thrombolytic therapy (p < 0.05). After a 90-day follow-up for mRS scores, a significant difference was only noted in the mRS scores of AIS patients from the third-class hospital after establishing the medical community model (p < 0.05). It was also found that the medical community model led to reduced length of hospital stay and hospitalization expenses for AIS patients, especially for the second-class hospitals.ConclusionThe data suggest that the medical community model could significantly reduce intravenous alteplase DNT and improve the prognosis of patients with AIS.

Background: The benefit of intravenous thrombolysis with alteplase before endovascular thrombectomy (EVT) for acute ischemic stroke due to large vessel occlusion remains debated. In this study, we analyzed the cost-effectiveness of EVT alone versus intravenous alteplase before EVT in patients directly admitted to EVT-capable stroke centers from the Dutch health care payer perspective., Methods: A decision analysis was performed using a Markov model with 15-year simulated follow-up to estimate total costs, quality-adjusted life years, and an incremental cost-effectiveness ratio of intravenous alteplase before EVT compared with EVT alone. A hypothetical cohort of 10 000 patients with large vessel occlusion aged 70 years was run in Monte Carlo simulation. Functional outcome of each treatment was derived from pooled results of 6 randomized controlled trials (RCTs). Uncertainty was assessed by probabilistic analyses, scenario analyses, and 1-way sensitivity analyses., Results: Using functional outcomes obtained from 6 RCTs (intention-to-treat population), intravenous alteplase before EVT resulted in 0.05 quality-adjusted life years gained at an additional $2817 compared with EVT alone, resulting in the incremental cost-effectiveness ratio of $62 287. Probabilistic analyses showed that intravenous alteplase before EVT had a probability of 45% and 54%, respectively, of being cost-effective at the $52 500 and $84 000 thresholds. Restricting functional outcomes from our post hoc modified as-treated analysis of 6 RCTs (scenario 1), European RCTs (scenario 2), or a Dutch RCT (scenario 3), intravenous alteplase before EVT was cost-effective in 64%, 81%, and 50% of simulations at the $52 500 threshold, and 79%, 91%, and 67% of simulations at the $84 000 threshold., Conclusions: Intravenous alteplase before EVT was not cost-effective in patients with large vessel occlusion in the Netherlands at the $52 500 threshold but possibly cost-effective at the $84 000 threshold. Variable functional outcomes at 3 months based on different trial populations affected the cost-effectiveness of intravenous alteplase before EVT., Competing Interests: Drs Majoie and Roos declare to be shareholders of Nico-Lab, not involved in this study. Dr Majoie has reported grants from CardioVascular Research Netherlands (CVON)/Dutch Heart Foundation, European Commission, Stichting Toegepast Wetenschappelijk Instituut voor Neuromodulatie (TWIN) Foundation, Health Evaluation Netherlands, Boehringer Ingelheim, and Stryker (all paid to institution). Dr Coutinho is the cofounder and shareholder of TrianecT. He has received grants from Medtronic, Boehringer Ingelheim, Bayer, and AstraZeneca and is a consultant at Portola Pharmaceuticals, LLC. Dr van der Zee is a member of the supervisory board at Radiotherapeutisch Instituut Friesland. Dr Buskens is appointed by University Medical Center Groningen, has reported receiving funding from the Netherlands Heart Foundation and a Public-Private Partnership allowance from Health Holland, Care Research Netherlands and Medical Sciences (ZonMw), and Dutch Research Council (NWO) and serves as the ZonMw committee (vice) chairman. Also, Dr Buskens serves at ZuidOost Zorg and 113 Suicide prevention as a member of advisory board. Dr Uyttenboogaart has received research grants from ZonMw and Dutch Heart Foundation. The other authors report no conflicts.

Angioedema without concomitant urticaria is a well-known complication of treatment with the recombinant tissue-type plasminogen activator (r-tPA) alteplase and its genetically modified variant tenecteplase. It is potentially lethal when causing airway obstruction and can require intubation. The latest guideline for the early management of patients with acute ischemic stroke from the American Heart Association/American Stroke Association advises to treat this complication initially by interfering with the histamine pathway. This article aims to clarify the pathophysiological mechanism of r-tPA-induced angioedema and provides several arguments that this condition is primarily bradykinin-mediated and hence should be treated initially by intervening with the bradykinin pathway. Second, other-less frequently reported-adverse symptoms after r-tPA therapy and their proposed pathophysiological mechanisms leading to specific treatment are described. This manuscript describes the need for an update of the section "3.5 IV alteplase" from the American Heart Association/American Stroke Association guideline to treat this r-tPA-induced angioedema adequately and prevent potentially fatal outcomes., Competing Interests: None.

Objectives: Patients waking up with stroke symptoms are often excluded from intravenous thrombolysis with alteplase (IV-tpa). The WAKE-UP trial, a European multicenter randomized controlled trial, proved the clinical effectiveness of magnetic resonance imaging-guided IV-tpa for these patients. This analysis aimed to assess the cost-effectiveness of the intervention compared to placebo.Methods: A Markov model was designed to analyze the cost-effectiveness over a 25-year time horizon. The model consisted of an inpatient acute care phase and a rest-of-life phase. Health states were defined by the modified Rankin Scale (mRS). Initial transition probabilities to mRS scores were based on WAKE-UP data and health state utilities on literature search. Costs were based on data from the University Medical Center Hamburg-Eppendorf, literature, and expert opinion. Incremental costs and effects over the patients' lifetime were estimated. The analysis was conducted from a formal German healthcare perspective. Univariate and probabilistic sensitivity analyses were performed.Results: Treatment with IV-tpa resulted in cost savings of €51 009 and 1.30 incremental gains in quality-adjusted life-years at a 5% discount rate. Univariate sensitivity analysis revealed incremental cost-effectiveness ratio being sensitive to the relative risk of favorable outcome on mRS for placebo patients after stroke, the costs of long-term care for patients with mRS 4, and patient age at initial stroke event. In all cases, IV-tpa remained cost-effective. Probabilistic sensitivity analysis proved IV-tpa cost-effective in >95% of the simulations results.Conclusions: Magnetic resonance imaging-guided IV-tpa compared to placebo is cost-effective in patients with ischemic stroke with unknown time of onset. [ABSTRACT FROM AUTHOR]

NMDA receptors (NMDA-Rs) are ionotropic glutamate receptors, which associate with LDL-receptor-related protein-1 (LRP1) to trigger cell signaling in response to protein ligands in neurons. Here, we demonstrate for the first time that the NMDA-R is expressed by rat Schwann cells and functions independently and with LRP1 to regulate Schwann cell physiology. The NR1 (encoded by GRIN1) and NR2b (encoded by GRIN2B) NMDA-R subunits were expressed by cultured Schwann cells and upregulated in sciatic nerves following crush injury. The ability of LRP1 ligands to activate ERK1/2 (also known as MAPK3 and MAPK1, respectively) and promote Schwann cell migration required the NMDA-R. NR1 gene silencing compromised Schwann cell survival. Injection of the LRP1 ligands tissue-type plasminogen activator (tPA, also known as PLAT) or MMP9-PEX into crush-injured sciatic nerves activated ERK1/2 in Schwann cells in vivo, and the response was blocked by systemic treatment with the NMDA-R inhibitor MK801. tPA was unique among the LRP1 ligands examined because tPA activated cell signaling and promoted Schwann cell migration by interacting with the NMDA-R independently of LRP1, albeit with delayed kinetics. These results define the NMDA-R as a Schwann cell signaling receptor for protein ligands and a major regulator of Schwann cell physiology, which may be particularly important in peripheral nervous system (PNS) injury.

Tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) are serine proteases and major activators of fibrinolysis in mammalian systems. Because fibrinolysis is an essential component of the response to tissue injury, diverse cells, including cells that participate in the response to injury, have evolved receptor systems to detect tPA and uPA and initiate appropriate cell-signaling responses. Formation of functional receptor systems for the plasminogen activators requires assembly of diverse plasma membrane proteins, including but not limited to: the urokinase receptor (uPAR); integrins; N-formyl peptide receptor-2 (FPR2), receptor tyrosine kinases (RTKs), the N-methyl-D-aspartate receptor (NMDA-R), and low-density lipoprotein receptor-related protein-1 (LRP1). The cell-signaling responses elicited by tPA and uPA impact diverse aspects of cell physiology. This review describes rapidly evolving knowledge regarding the structure and function of plasminogen activator receptor assemblies. How these receptor assemblies regulate innate immunity and inflammation is then considered. [ABSTRACT FROM AUTHOR]

Background and purposeBody temperature (BT) is an important physiological factor in acute ischemic stroke. However, the relationship of initial BT to stroke severity and degree of benefit from thrombolytic therapy has been delineated incompletely.MethodsWe analyzed the public data set of the 2 National Institute of Neurological Disorders and Stroke Tissue-Type Plasminogen Activator (tPA) stroke trials, comparing patients with lower (

Abstract Background Astrocytes contribute to the crosstalk that generates chronic neuro-inflammation in neurological diseases; however, compared with microglia, astrocytes respond to a more limited continuum of innate immune system stimulants. Recent studies suggest that the fibrinolysis system may regulate inflammation. The goal of this study was to test whether fibrinolysis system components activate astrocytes and if so, elucidate the responsible biochemical pathway. Methods Primary cultures of astrocytes and microglia were prepared from neonatal mouse brains. The ability of purified fibrinolysis system proteins to elicit a pro-inflammatory response was determined by measuring expression of the mRNAs encoding tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and chemokine (C-C motif) ligand 2 (CCL2). IκBα phosphorylation also was measured. Plasminogen activation in association with cells was detected by chromogenic substrate hydrolysis. The activity of specific receptors was tested using neutralizing antibodies and reagents. Results Astrocytes expressed pro-inflammatory cytokines when treated with plasminogen but not when treated with agonists for Toll-like Receptor-4 (TLR4), TLR2, or TLR9. Microglia also expressed pro-inflammatory cytokines in response to plasminogen; however, in these cells, the response was observed only when tissue-type plasminogen activator (tPA) was added to activate plasminogen. In astrocytes, endogenously produced urokinase-type plasminogen activator (uPA) converted plasminogen into plasmin in the absence of tPA. Plasminogen activation was dependent on the plasminogen receptor, α-enolase, and the uPA receptor, uPAR. Although uPAR is capable of directly activating cell-signaling, the receptor responsible for cytokine expression and IκBα phosphorylation response to plasmin was Protease-activated Receptor-1 (PAR-1). The pathway, by which plasminogen induced astrocyte activation, was blocked by inhibiting any one of the three receptors implicated in this pathway with reagents such as εACA, α-enolase-specific antibody, uPAR-specific antibody, the uPA amino terminal fragment, or a pharmacologic PAR-1 inhibitor. Conclusions Plasminogen may activate astrocytes for pro-inflammatory cytokine expression through the concerted action of at least three distinct fibrinolysis protease receptors. The pathway is dependent on uPA to activate plasminogen, which is expressed endogenously by astrocytes in culture but also may be provided by other cells in the astrocytic cell microenvironment in the CNS.

Background and purpose: The efficacy and safety of mechanical thrombectomy (MT) for M2 segment occlusion of middle cerebral artery in patients with acute ischemic stroke (AIS) was investigated. Methods: We searched PubMed and EMBASE from inception to 16 April 2019 for relevant studies, calculated the pool relative risks (RRs) of 3-month functional independence (modified Rankin scale score 0–2), death and symptomatic intracerebral hemorrhage (sICH) in MT for M2 segment occlusion in patients with AIS versus those of M1 segment or best medical care. Results: Nine studies enrolling 2152 patients compared MT for patients with AIS of M2 segment occlusion and those of M1 segment occlusion. MT for M2 occlusion had a higher rate of 3-month functional independence compared to the patients with M1 occlusion. (RR 1.27, 95% CI 1.11–1.44, P < 0.001) and decreased death (RR 0.74; 95% CI 0.58–0.96, P = 0.022) with similar risk of sICH (RR 1.11; 95% CI 0.65–1.87, P = 0.707). Four studies enrolling 1016 patients compared MT and best medical care for patients with AIS of M2 occlusion. MT for M2 occlusion benefit more than best medical care on 3-month functional independence (RR 1.43, 95% CI 1.08–1.90, P = 0.011) and death (RR 0.46; 95% CI 0.22–0.96, P = 0.022) with similar risk of sICH (RR 1.65; 95% CI 0.66–4.13; P = 0.286). Conclusion: MT for M2 segment benefit patients with AIS on 3-month functional independence compared with that of M1 segment or medical care, without increasing the risk of sICH. [ABSTRACT FROM AUTHOR]