Tissue-type plasminogen activator neutralizes LPS but not protease-activated receptor-mediated inflammatory responses to plasmin

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.

The role of oral fluvastatin on postoperative peritoneal adhesion formation in an experimental rat model

BACKGROUND

Postoperative peritoneal adhesions are a momentousness complication after abdominal surgery. Although varied means have been used to prevent and treat adhesions, the effects have not been satisfactory. Fluvastatin, a HMG-CoA reductase inhibitors, exhibits a variety of pharmacological effects. Aim of this study was to evaluate the effect of fluvastatin on postoperative peritoneal adhesion formation.

METHODS

Seventy-five male Wistar rats weighting 220-250g were randomly assigned equally to three groups. Group A was given sham operation without treatment, Group B was the model group in which postoperative peritoneal adhesion model was created without medication, and Group C was given oral fluvastatin treatment after postoperative peritoneal adhesion model created. After laparotomy on day 7, macroscopic and pathological assessment were evaluated, IL-1β and t-PA in plasma were performed to measure, and tissue samples were taken to measure MMP-9 protein.

RESULTS

There were significant differences between the groups on adhesion grade (p < .05), IL-1β content of the plasma and t-PA activity of the adhesions (p < .05). The grading of adhesion demonstrated significant differences between all groups. The levels of the IL-1β content of plasma, t-PA activity and MMP-9 of adhesion showed pivotal changes in Group B compared with Group A and C, while the difference between Group A and C was not statistically significant.

CONCLUSION

Oral fluvastatin application could reduce formation of intra-abdominal adhesion by promoting expression of MMP-9 level, lowering the levels of IL-1β and increasing the activity of t-PA after abdominal surgery.

Amyloid beta soluble forms and plasminogen activation system in Alzheimer's disease: Consequences on extracellular maturation of brain-derived neurotrophic factor and therapeutic implications

Soluble oligomeric forms of amyloid beta (Aβ) play an important role in causing the cognitive deficits in Alzheimer’s disease (AD) by targeting and disrupting synaptic pathways. Thus, the present research is directed toward identifying the neuronal pathways targeted by soluble forms and, accordingly, develops alternative therapeutic strategies. The neurotrophin brain‐derived neurotrophic factor (BDNF) is synthesized as a precursor (pro‐BDNF) which is cleaved extracellularly by plasmin to release the mature form. The conversion from pro‐BDNF to BDNF is an important process that regulates neuronal activity and memory processes. Plasmin‐dependent maturation of BDNF in the brain is regulated by plasminogen activator inhibitor‐1 (PAI‐1), the natural inhibitor of tissue‐type plasminogen activator (tPA). Therefore, tPA/PAI‐1 system represents an important regulator of extracellular BDNF/pro‐BDNF ratio. In this review, we summarize the data on the components of the plasminogen activation system and on BDNF in AD. Moreover, we will hypothesize a possible pathogenic mechanism caused by soluble Aβ forms based on the effects on tPA/PAI‐1 system and on the consequence of an altered conversion from pro‐BDNF to the mature BDNF in the brain of AD patients. Translation into clinic may include a better characterization of the disease stage and future direction on therapeutic targets.

Rivaroxaban and apixaban induce clotting factor Xa fibrinolytic activity

Essentials Activated clotting factor X (FXa) acquires fibrinolytic cofactor function after cleavage by plasmin. FXa-mediated plasma fibrinolysis is enabled by active site modification blocking a second cleavage. FXa-directed oral anticoagulants (DOACs) alter FXa cleavage by plasmin. DOACs enhance FX-dependent fibrinolysis and plasmin generation by tissue plasminogen activator.

BACKGROUND

When bound to an anionic phospholipid-containing membrane, activated clotting factor X (FXa) is sequentially cleaved by plasmin from the intact form, FXaα, to FXaβ and then to Xa33/13. Tissue-type plasminogen activator (t-PA) produces plasmin and is the initiator of fibrinolysis. Both FXaβ and Xa33/13 enhance t-PA-mediated plasminogen activation. Although stable in experiments using purified proteins, Xa33/13 rapidly loses t-PA cofactor function in plasma. Bypassing this inhibition, covalent modification of the FXaα active site prevents Xa33/13 formation by plasmin, and the persistent FXaβ enhances plasma fibrinolysis. As the direct oral anticoagulants (DOACs) rivaroxaban and apixaban bind to the FXa active site, we hypothesized that they similarly modulate FXa fibrinolytic function.

METHODS

DOAC effects on fibrinolysis and the t-PA cofactor function of FXa were studied in patient plasma, normal pooled plasma and purified protein experiments by the use of light scattering, chromogenic assays, and immunoblots.

RESULTS

The plasma of patients taking rivaroxaban showed enhanced fibrinolysis correlating with FXaβ. In normal pooled plasma, the addition of rivaroxaban or apixaban also shortened fibrinolysis times. This was related to the cleavage product, FXaβ, which increased plasmin production by t-PA. It was confirmed that these results were not caused by DOACs affecting activated FXIII-mediated fibrin crosslinking, clot ultrastructure and thrombin-activatable fibrinolysis inhibitor activation in plasma.

CONCLUSION

The current study suggests a previously unknown effect of DOACs on FXa in addition to their well-documented anticoagulant role. By enabling the t-PA cofactor function of FXaβ in plasma, DOACs also enhance fibrinolysis. This effect may broaden their therapeutic indications.

Real-World Outcomes of Acute Ischemic Stroke Treatment with Intravenous Thrombolysis: A Systematic Review and Meta-Analysis

BACKGROUND

Evidence from outside the typical clinical research setting, such as the real-world setting, complements evidence coming from randomized controlled trials. The purpose of this study was to evaluate all available evidence from the real-world observational trials about long-term outcomes of treatment with intravenous (IV) recombinant tissue-type plasminogen activator (rt-PA) compared with not treated with IV rt-PA (non-rt-PA) in patients with acute ischemic stroke.

METHODS

We searched PubMed and Embase until March 1, 2018 for observational studies reporting matched or adjusted results comparing IV rt-PA versus non-rt-PA in patients with acute ischemic stroke. Outcomes assessed included all-cause mortality, hospital readmission rates, and independence rates. Hazard ratios with 95% confidence intervals were used as a measure of comparing between patients treated with IV rt-PA and non-rt-PA.

RESULTS

Six observational trials with 16,399 participants were identified. The use of IV rt-PA in acute ischemic stroke patients was associated with a lower risk of mortality (hazard ratio .61; 95% confidence interval, .52-.70; P < .00001), and there was no heterogeneity across trials. There was no evidence of an effect on hospital readmission rates and independence rates.

CONCLUSIONS

IV rt-PA is associated with reduced long-term mortality in acute ischemic stroke patients.

Taurine Reduces tPA (Tissue-Type Plasminogen Activator)-Induced Hemorrhage and Microvascular Thrombosis After Embolic Stroke in Rat

BACKGROUND AND PURPOSE

Taurine (2-aminoethansulfolic amino acid) exerts neuroprotective actions in experimental stroke. Here, we investigated the effect of taurine in combination with delayed tPA (tissue-type plasminogen activator) on embolic stroke.

METHODS

Rats subjected to embolic middle cerebral artery occlusion were treated with taurine (50 mg/kg) at 4 hours in combination with tPA (10 mg/kg) at 6 hours. Control groups consisted of ischemic rats treated with either taurine (50 mg/kg) or saline at 4 hours or tPA (10 mg/kg) alone at 2 or 6 hours after middle cerebral artery occlusion.

RESULTS

We found that combination treatment with taurine and tPA robustly reduced infarct volume and neurological deficits 3 days after stroke, whereas treatment with taurine alone had a less-significant protective effect. tPA alone at 6 hours had no effects on infarct volume but instead induced intracerebral hemorrhage. The combination treatment with taurine prevented tPA-associated hemorrhage and reduced intravascular deposition of fibrin/fibrinogen and platelets in downstream microvessels and hence improved microvascular patency. These protective effects are associated with profound inhibition of CD147 (cluster of differentiation 147)-dependent MMP-9 (matrix metalloproteinase-9) pathway in ischemic brain endothelium by taurine. Notably, targeted inhibition of CD147 by intracerebroventricular injection of the rat CD147 siRNA profoundly inhibited ischemia-induced and tPA-enhanced MMP-9 activity in ischemic brain endothelium and blocked tPA-induced cerebral hemorrhage. Finally, the combination treatment with taurine and tPA improved long-term outcome at least 45 days after stroke compared with saline-treated group.

CONCLUSIONS

Our results suggest that taurine in combination with tPA may be a clinically feasible approach toward future attempts at combination stroke therapy.

Regulation of plasminogen activation on cell surfaces and fibrin

The fibrinolytic system dissolves fibrin and maintains vascular patency. Recent advances in imaging analyses allowed visualization of the spatiotemporal regulatory mechanism of fibrinolysis, as well as its regulation by other plasma hemostasis cofactors. Vascular endothelial cells (VECs) retain tissue-type plasminogen activator (tPA) after secretion and maintain high plasminogen (plg) activation potential on their surfaces. As in plasma, the serpin, plasminogen activator inhibitor type 1 (PAI-1), regulates fibrinolytic potential via inhibition of the VEC surface-bound plg activator, tPA. Once fibrin is formed, plg activation by tPA is initiated and effectively amplified on the surface of fibrin, and fibrin is rapidly degraded. The specific binding of plg and tPA to lytic edges of partly degraded fibrin via newly generated C-terminal lysine residues, which amplifies fibrin digestion, is a central aspect of this pathophysiological mechanism. Thrombomodulin (TM) plays a role in the attenuation of plg binding on fibrin and the associated fibrinolysis, which is reversed by a carboxypeptidase B inhibitor. This suggests that the plasma procarboxypeptidase B, thrombin-activatable fibrinolysis inhibitor (TAFI), which is activated by thrombin bound to TM on VECs, is a critical aspect of the regulation of plg activation on VECs and subsequent fibrinolysis. Platelets also contain PAI-1, TAFI, TM, and the fibrin cross-linking enzyme, factor (F) XIIIa, and either secrete or expose these agents upon activation in order to regulate fibrinolysis. In this review, the native machinery of plg activation and fibrinolysis, as well as their spatiotemporal regulatory mechanisms, as revealed by imaging analyses, are discussed.

Intravenous Recombinant Tissue-Type Plasminogen Activator: Influence on Outcome in Anterior Circulation Ischemic Stroke Treated by Mechanical Thrombectomy

BACKGROUND AND PURPOSE

Intravenous thrombolysis (IVT) followed by mechanical thrombectomy (MT) improves functional outcome in patients with ischemic stroke related to proximal-vessel occlusion in the anterior circulation. Whether MT alone is as effective as IVT/MT remains controversial. We aimed at evaluating the influence of IVT in patients with large anterior circulation artery occlusion treated with MT.

METHODS

We did a prospective observational cohort study in patients with stroke related to large anterior circulation artery occlusion treated by MT who were admitted to Lille University Hospital, Lille, France. We evaluated the influence of IVT on favorable functional outcome (defined as a modified Rankin Scale score 0-2 or similar to the prestroke modified Rankin Scale) and on mortality at month 3. Between-group comparisons in outcomes were adjusted for prespecified confoundors by using a propensity score-adjusted approach.

RESULTS

From January 2012 to January 2017, we included 485 patients (median age, 68 years; 46% men; 348 [72%] in the IVT/MT group; 137 [28%] in the MT group). In MT group, 22% of patients had a favorable outcome versus 35% in IVT/MT group (adjusted relative risk, 1.76; 95% confidence interval, 1.23-2.55). Mortality within 3 months occurred less frequently in IVT/MT group (14% versus 32%; adjusted relative risk, 0.46; 95% confidence interval, 0.31-0.70). Successful reperfusion (Thrombolysis in Cerebral Infarction scale 2b-3) was more frequent in IVT/MT group (75% versus 60%; adjusted relative risk, 1.30; 95% confidence interval, 1.11-1.53). There was no difference between groups on hemorrhagic complications.

CONCLUSIONS

In this population, previous IVT improved functional outcome and survival at 3 months in patients treated by MT. While waiting for randomized controlled trials, this result encourages not to avoid IVT before MT.

Intravenous Thrombolysis for Stroke and Presumed Stroke in Human Immunodeficiency Virus-Infected Adults: A Retrospective, Multicenter US Study

BACKGROUND AND PURPOSE

Human immunodeficiency virus (HIV) infection has been shown to increase both ischemic and hemorrhagic stroke risks, but there are limited data on the safety and outcomes of intravenous thrombolysis with tPA (tissue-type plasminogen activator) for acute ischemic stroke in HIV-infected patients.

METHODS

A retrospective chart review of intravenous tPA-treated HIV patients who presented with acute stroke symptoms was performed in 7 large inner-city US academic centers (various search years between 2000 and 2017). We collected data on HIV, National Institutes of Health Stroke Scale score, ischemic stroke risk factors, opportunistic infections, intravenous drug abuse, neuroimaging findings, and modified Rankin Scale score at last follow-up.

RESULTS

We identified 33 HIV-infected patients treated with intravenous tPA (mean age, 51 years; 24 men), 10 of whom were stroke mimics. Sixteen of 33 (48%) patients had an HIV viral load less than the limit of detection while 10 of 33 (30%) had a CD4 count <200/mm³. The median National Institutes of Health Stroke Scale score at presentation was 9, and mean time from symptom onset to tPA was 144 minutes (median, 159). The median modified Rankin Scale score for the 33-patient cohort was 1 and for the 23-patient actual stroke cohort was 2, measured at a median of 90 days poststroke symptom onset. Two patients had nonfatal hemorrhagic transformation (6%; 95% confidence interval, 1%-20%), both in the actual stroke group. Two patients had varicella zoster virus vasculitis of the central nervous system, 1 had meningovascular syphilis, and 7 other patients were actively using intravenous drugs (3 cocaine, 1 heroin, and 3 unspecified), none of whom had hemorrhagic transformation.

CONCLUSIONS

Most HIV-infected patients treated with intravenous tPA for presumed and actual acute ischemic stroke had no complications, and we observed no fatalities. Stroke mimics were common, and thrombolysis seems safe in this group. We found no data to suggest an increased risk of intravenous tPA-related complications because of concomitant opportunistic infections or intravenous drug abuse.

Geographic Modeling to Quantify the Impact of Primary and Comprehensive Stroke Center Destination Policies

BACKGROUND AND PURPOSE

We evaluated the impact of a primary stroke center (PSC) destination policy in a major metropolitan city and used geographic modeling to evaluate expected changes for a comprehensive stroke center policy.

METHODS

We identified suspected stroke emergency medical services encounters from 1/1/2004 to 12/31/2013 in Philadelphia, PA. Transport times were compared before and after initiation of a PSC destination policy on 10/3/2011. Geographic modeling estimated the impact of bypassing the closest hospital for the closest PSC and for the closest comprehensive stroke center.

RESULTS

There were 2 326 943 emergency medical services runs during the study period, of which 15 099 had a provider diagnosis of stroke. Bypassing the closest hospital for a PSC was common before the official policy and increased steadily over time. Geographic modeling suggested that bypassing the closest hospital in favor of the closest PSC adds a median of 3.1 minutes to transport time. Bypassing to the closest comprehensive stroke center would add a median of 8.3 minutes.

CONCLUSIONS

Within a large metropolitan area, the time cost of routing patients preferentially to PSCs and comprehensive stroke centers is low.

Novel Telestroke Program Improves Thrombolysis for Acute Stroke Across 21 Hospitals of an Integrated Healthcare System

Supplemental Digital Content is available in the text.

Background and Purpose—

Faster treatment with intravenous alteplase in acute ischemic stroke is associated with better outcomes. Starting in 2015, Kaiser Permanente Northern California redesigned its acute stroke workflow across all 21 Kaiser Permanente Northern California stroke centers to (1) follow a single standardized version of a modified Helsinki model and (2) have all emergency stroke cases managed by a dedicated telestroke neurologist. We examined the effect of Kaiser Permanente Northern California’s Stroke EXpediting the PRrocess of Evaluating and Stopping Stroke program on door-to-needle (DTN) time, alteplase use, and symptomatic intracranial hemorrhage rates.

Methods—

The program was introduced in a staggered fashion from September 2015 to January 2016. We compared DTN times for a seasonally adjusted 9-month period at each center before implementation to the corresponding 9-month calendar period from the start of implementation. The primary outcome was the DTN time for alteplase administration. Secondary outcomes included rate of alteplase administrations per month, symptomatic intracranial hemorrhage, and disposition at time of discharge.

Results—

This study included 310 patients treated with alteplase in the pre–EXpediting the PRrocess of Evaluating and Stopping Stroke period and 557 patients treated with alteplase in the EXpediting the PRrocess of Evaluating and Stopping Stroke period. After implementation, alteplase administrations increased to 62/mo from 34/mo at baseline (P<0.001). Median DTN time decreased to 34 minutes after implementation from 53.5 minutes prior (P<0.001), and DTN time of <60 minutes was achieved in 87.1% versus 61.0% (P<0.001) of patients. DTN times <30 minutes were much more common in the Stroke EXpediting the PRrocess of Evaluating and Stopping Stroke period (40.8% versus 4.2% before implementation). There was no significant difference in symptomatic intracranial hemorrhage rates in the 2 periods (3.8% versus 2.2% before implementation; P=0.29).

Conclusions—

Introduction of a standardized modified Helsinki protocol across 21 hospitals using telestroke management was associated with increased alteplase administrations, significantly shorter DTN times, and no increase in adverse outcomes.

Sickle Mice Are Sensitive to Hypoxia/Ischemia-Induced Stroke but Respond to Tissue-Type Plasminogen Activator Treatment

BACKGROUND AND PURPOSE

The effects of lytic stroke therapy in patients with sickle cell anemia are unknown, although a recent study suggested that coexistent sickle cell anemia does not increase the risk of cerebral hemorrhage. This finding calls for systemic analysis of the effects of thrombolytic stroke therapy, first in humanized sickle mice, and then in patients. There is also a need for additional predictive markers of sickle cell anemia-associated vasculopathy.

METHODS

We used Doppler ultrasound to examine the carotid artery of Townes sickle mice tested their responses to repetitive mild hypoxia-ischemia- and transient hypoxia-ischemia-induced stroke at 3 or 6 months of age, respectively. We also examined the effects of tPA (tissue-type plasminogen activator) treatment in transient hypoxia-ischemia-injured sickle mice.

RESULTS

Three-month-old sickle cell (SS) mice showed elevated resistive index in the carotid artery and higher sensitivity to repetitive mild hypoxia-ischemia-induced cerebral infarct. Six-month-old SS mice showed greater resistive index and increased flow velocity without obstructive vasculopathy in the carotid artery. Instead, the cerebral vascular wall in SS mice showed ectopic expression of PAI-1 (plasminogen activator inhibitor-1) and P-selectin, suggesting a proadhesive and prothrombotic propensity. Indeed, SS mice showed enhanced leukocyte and platelet adherence to the cerebral vascular wall, broader fibrin deposition, and higher mortality after transient hypoxia-ischemia. Yet, post-transient hypoxia-ischemia treatment with tPA reduced thrombosis and mortality in SS mice.

CONCLUSIONS

Sickle mice are sensitive to hypoxia/ischemia-induced cerebral infarct but benefit from thrombolytic treatment. An increased resistive index in carotid arteries may be an early marker of sickle cell vasculopathy.

Investigation of Gender Differences and Exclusive Criteria in a Diabetic Acute Ischemic Stroke Population Treated with Recombinant Tissue-Type Plasminogen Activator (rtPA)

BACKGROUND

Many studies have reported that women who survive stroke have less favorable outcomes than men in the use of rtPA, while others reported worse outcomes in men than women. The gender difference in the exclusion criteria in a diabetic stroke population is not fully understood. This issue was investigated in this study.

METHOD

In a diabetic stroke population from a stroke registry of data collected between January 2010 to June 30, 2016, the gender difference was determined using demographics and clinical factors. Comparison was determined using univariate analysis while multivariable model was used to adjust for the effect of confounding variables.

RESULTS

In a diabetic stroke population of 439 patients, more females were excluded than males (P < 0.0001, OR = 2.323). The male exclusion was associated with atrial fibrillation (P = 0.011, OR = 3.697), carotid artery stenosis (P = 0.023, OR = 5.001), and cholesterol reducer (P = 0.037, OR = 0.409). In the female diabetic stroke population, exclusion from rtPA therapy was associated with language disturbances (P = 0.039, OR = 0.372), history of previous stroke (P = 0.005, OR = 3.276), antihypertensive medication use (P = 0.013, OR = 0.163), and antidiabetic medication use (P = 0.031, OR = 0.324).

CONCLUSION

In a stroke population, women have a worse outcome than men in an untreated acute ischemic stroke population, but when treated there is no significant difference, suggesting a better treatment outcome for women compared to men. In a diabetic stroke population, the clinical variables for the exclusion criteria for women and men are significantly different, even after adjustment for confounding variables.

Timely Reperfusion in Stroke and Myocardial Infarction Is Not Correlated: An Opportunity for Better Coordination of Acute Care

BACKGROUND

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.

METHODS AND RESULTS

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 <60 minutes: 21% [interquartile range, 11-30]; median D2B time <90 minutes: 68% [interquartile range, 62-79]; ρ=-0.14; P=0.36). The lack of correlation between hospitals' DTN and D2B times persisted after risk adjustment. We also correlated hospitals' DTN time and D2B time data from 2013 to 2014 using Get With The Guidelines (DTN time) and Hospital Compare (D2B time). From 2013 to 2014, hospitals' DTN time performance in Get With The Guidelines was not correlated with D2B time performance in Hospital Compare (n=546 hospitals).

CONCLUSIONS

We found no correlation between hospitals' observed or risk-adjusted DTN and D2B times. Opportunities exist to improve hospitals' performance of time-critical care processes for AIS and STEMI in a coordinated approach.

Tissue-type plasminogen activator modulates macrophage M2 to M1 phenotypic change through annexin A2-mediated NF-κB pathway

Macrophage accumulation is one of the hallmarks of progressive kidney disease. In response to injury, macrophages undergo a phenotypic polarization to become two functionally distinct subsets: M1 and M2 macrophages. Macrophage polarization is a dynamic process, and recent work indicates that macrophages, in response to kidney injury, can shift their polarity. However, the underlying mechanisms remain largely unknown. Tissue-type plasminogen activator (tPA), a protease up-regulated in the chronically injured kidneys, has been shown to preferably promote M1 macrophage accumulation and renal inflammation. We hypothesized that tPA may be an endogenous factor that modulates macrophage M2 to M1 phenotypic change contributing to the accumulation of M1 macrophages in the injured kidneys. It was found that obstruction-induced renal M1 chemokine expression was alleviated in tPA knockout mice, and these knockout mice displayed increased M2 markers. In vitro, resting J774 macrophages were treated with IL-4 to induce M2 phenotype as indicated by de novo expression of arginase 1, Ym1, and IL-10, as well as suppression of iNOS, TNF-α, and IL-1β. Intriguingly, these IL-4-induced M2 macrophages, after tPA treatment, not only lost their M2 markers such as arginase 1, Ym1, and IL-10, but also displayed increased M1 chemokines including iNOS, TNF-α, and IL-1β. Possible endotoxin contamination was also excluded as heat-inactivated tPA lost its effect. Additionally, tPA-mediated macrophage M2 to M1 phenotypic change required its receptor annexin A2, and SN50, a specific NF-κB inhibitor, abolished tPA's effect. Thus, it's clear that tPA promotes macrophage M2 to M1 phenotypic change through annexin A2-mediated NF-κB pathway.

Neural correlates of food anticipatory activity in mice subjected to once- or twice-daily feeding periods

In rodents, restricted food access to a limited period each day at a predictable time results in the appearance of food anticipatory activity (FAA). Two shorter periods of food access each day can result in two FAA bouts. In this study, we examine FAA under 12:12 and 18:6 photoperiods in mice (Mus musculus) with one or two food access periods per day and measure the activation of the suprachiasmatic, dorsomedial and arcuate nuclei by assaying Fos protein expression, while making use of tissue-type plasminogen activator knockout mice to assess the role of neural plasticity in adaptation to restricted feeding cycles. Long days were utilised to allow for temporal separation of two restricted feeding periods during the light phase. Mice fed twice per day generally divided FAA into two distinct bouts, with mice lacking tissue-type plasminogen activator showing reduced FAA. Increases in Fos expression in response to one restricted feeding period per day were seen in the dorsomedial and arcuate nuclei in both 12:12 and 18:6 conditions, with an increase seen in the SCN in only the 12:12 condition. These increases were eliminated or reduced in the two feeding time conditions (done in 18:6 only). Both activity patterns and Fos expression differed for single restricted feeding times between 18:6 and 12:12 photoperiods. Fos activation was lower during RF in 18:6 than 12:12 across all three brain regions, a pattern not reflective of changes in FAA. These data suggest that involvement of these regions in FAA may be influenced by photoperiodic context.

Role of tissue-type plasminogen activator and plasminogen activator inhibitor-1 in psychological stress and depression

Major depressive disorder is a common illness worldwide, but the pathogenesis of the disorder remains incompletely understood. The tissue-type plasminogen activator-plasminogen proteolytic cascade is highly expressed in the brain regions involved in mood regulation and neuroplasticity. Accumulating evidence from animal and human studies suggests that tissue-type plasminogen activator and its chief inhibitor, plasminogen activator inhibitor-1, are related to stress reaction and depression. Furthermore, the neurotrophic hypothesis of depression postulates that compromised neurotrophin brain-derived neurotrophic factor (BDNF) function is directly involved in the pathophysiology of depression. In the brain, the proteolytic cleavage of proBDNF, a BDNF precursor, to mature BDNF through plasmin represents one mechanism that can change the direction of BDNF action. We also discuss the implications of tissue-type plasminogen activator and plasminogen activator inhibitor-1 alterations as biomarkers for major depressive disorder. Using drugs that increase tissue-type plasminogen activator or decrease plasminogen activator inhibitor-1 levels may open new avenues to develop conceptually novel therapeutic strategies for depression treatment.

Urokinase vs Tissue-Type Plasminogen Activator for Thrombolytic Evacuation of Spontaneous Intracerebral Hemorrhage in Basal Ganglia

Spontaneous intracerebral hemorrhage (ICH) is a devastating form of stroke, which leads to a high rate of mortality and poor neurological outcomes worldwide. Thrombolytic evacuation with urokinase-type plasminogen activator (uPA) or tissue-type plasminogen activator (tPA) has been showed to be a hopeful treatment for ICH. However, to the best of our knowledge, no clinical trials were reported to compare the efficacy and safety of these two fibrinolytics administrated following minimally invasive stereotactic puncture (MISP) in patients with spontaneous basal ganglia ICH. Therefore, the authors intended here to evaluate the differential impact of uPA and tPA in a retrospective study. In the present study, a total of 86 patients with spontaneous ICH in basal ganglia using MISP received either uPA (uPA group, n = 45) or tPA (tPA group, n = 41), respectively. The clinical baseline characteristics prior to the operation were collected. In addition, therapeutic responses were assessed by the short-term outcomes within 30 days postoperation, as well as long-term outcomes at 1 year postoperation. Our findings showed that, in comparison with tPA, uPA was able to better promote hematoma evacuation and ameliorate perihematomal edema, but the differences were not statistically significant. Moreover, the long-term functional outcomes of both groups were similar, with no statistical difference. In conclusion, these results provide evidence supporting that uPA and tPA are similar in the efficacy and safety for thrombolytic evacuation in combination with MISP in patients with spontaneous basal ganglia ICH.

Door-to-Needle Delays in Minor Stroke: A Causal Inference Approach

BACKGROUND AND PURPOSE

Thrombolysis rates among minor stroke (MS) patients are increasing because of increased recognition of disability in this group and guideline changes regarding treatment indications. We examined the association of delays in door-to-needle (DTN) time with stroke severity.

METHODS

We performed a retrospective analysis of all stroke patients who received intravenous tissue-type plasminogen activator in our emergency department between July 1, 2011, and February 29, 2016. Baseline characteristics and DTN were compared between MS (National Institutes of Health Stroke Scale score ≤5) and nonminor strokes (National Institutes of Health Stroke Scale score >5). We applied causal inference methodology to estimate the magnitude and mechanisms of the causal effect of stroke severity on DTN.

RESULTS

Of 315 patients, 133 patients (42.2%) had National Institutes of Health Stroke Scale score ≤5. Median DTN was longer in MS than nonminor strokes (58 versus 53 minutes; P=0.01); fewer MS patients had DTN ≤45 minutes (19.5% versus 32.4%; P=0.01). MS patients were less likely to use emergency medical services (EMS; 62.6% versus 89.6%, P<0.01) and to receive EMS prenotification (43.9% versus 72.4%; P<0.01). Causal analyses estimated MS increased average DTN by 6 minutes, partly through mode of arrival. EMS prenotification decreased average DTN by 10 minutes in MS patients.

CONCLUSIONS

MS had longer DTN times, an effect partly explained by patterns of EMS prenotification. Interventions to improve EMS recognition of MS may accelerate care.

Urokinase, a promising candidate for fibrinolytic therapy for intracerebral hemorrhage

OBJECTIVE Intracerebral hemorrhage (ICH) is associated with a high rate of mortality and severe disability, while fibrinolysis for ICH evacuation is a possible treatment. However, reported adverse effects can counteract the benefits of fibrinolysis and limit the use of tissue-type plasminogen activator (tPA). Identifying appropriate fibrinolytics is still needed. Therefore, the authors here compared the use of urokinase-type plasminogen activator (uPA), an alternate thrombolytic, with that of tPA in a preclinical study. METHODS Intracerebral hemorrhage was induced in adult male Sprague-Dawley rats by injecting autologous blood into the caudate, followed by intraclot fibrinolysis without drainage. Rats were randomized to receive uPA, tPA, or saline within the clot. Hematoma and perihematomal edema, brain water content, Evans blue fluorescence and neurological scores, matrix metalloproteinases (MMPs), MMP mRNA, blood-brain barrier (BBB) tight junction proteins, and nuclear factor-κB (NF-κB) activation were measured to evaluate the effects of these 2 drugs in ICH. RESULTS In comparison with tPA, uPA better ameliorated brain edema and promoted an improved outcome after ICH. In addition, uPA therapy more effectively upregulated BBB tight junction protein expression, which was partly attributed to the different effects of uPA and tPA on the regulation of MMPs and its related mRNA expression following ICH. CONCLUSIONS This study provided evidence supporting the use of uPA for fibrinolytic therapy after ICH. Large animal experiments and clinical trials are required to further explore the efficacy and safety of uPA in ICH fibrinolysis.

Telemedicine Can Replace the Neurologist on a Mobile Stroke Unit

BACKGROUND AND PURPOSE

The BEST-MSU study (Benefits of Stroke Treatment Delivered Using a Mobile Stroke Unit) is a comparative effectiveness trial in patients randomized to mobile stroke unit or standard management. A substudy tested interrater agreement for tissue-type plasminogen activator eligibility between a telemedicine vascular neurologist and onboard vascular neurologist.

METHODS

On scene, both the telemedicine vascular neurologist and onboard vascular neurologist independently evaluated the patient, documenting their tissue-type plasminogen activator treatment decision, National Institutes of Health Stroke Scale score, and computed tomographic interpretation. Agreement was determined using Cohen κ statistic. Telemedicine-related technical failures that impeded remote assessment were recorded.

RESULTS

Simultaneous and independent telemedicine vascular neurologist and onboard vascular neurologist assessment was attempted in 174 patients. In 4 patients (2%), the telemedicine vascular neurologist could not make a decision because of technical problems. The telemedicine vascular neurologist agreed with the onboard vascular neurologist on 88% of evaluations (κ=0.73).

CONCLUSIONS

Remote telemedicine vascular neurologist assessment is reliable and accurate, supporting either telemedicine vascular neurologist or onboard vascular neurologist assessment on our mobile stroke unit.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02190500.

Urokinase-type plasminogen activator modulates mammalian circadian clock phase regulation in tissue-type plasminogen activator knockout mice

Glutamate phase shifts the circadian clock in the mammalian suprachiasmatic nucleus (SCN) by activating NMDA receptors. Tissue-type plasminogen activator (tPA) gates phase shifts by activating plasmin to generate m(ature) BDNF, which binds TrkB receptors allowing clock phase shifts. Here, we investigate phase shifting in tPA knockout (tPA^-/- ; B6.129S2-Plat^tm1Mlg /J) mice, and identify urokinase-type plasminogen activator (uPA) as an additional circadian clock regulator. Behavioral activity rhythms in tPA^-/- mice entrain to a light-dark (LD) cycle and phase shift in response to nocturnal light pulses with no apparent loss in sensitivity. When the LD cycle is inverted, tPA^-/- mice take significantly longer to entrain than C57BL/6J wild-type (WT) mice. SCN brain slices from tPA^-/- mice exhibit entrained neuronal activity rhythms and phase shift in response to nocturnal glutamate with no change in dose-dependency. Pre-treating slices with the tPA/uPA inhibitor, plasminogen activator inhibitor-1 (PAI-1), inhibits glutamate-induced phase delays in tPA^-/- slices. Selective inhibition of uPA with UK122 prevents glutamate-induced phase resetting in tPA^-/- but not WT SCN slices. tPA expression is higher at night than the day in WT SCN, while uPA expression remains constant in WT and tPA^-/- slices. Casein-plasminogen zymography reveals that neither tPA nor uPA total proteolytic activity is under circadian control in WT or tPA^-/- SCN. Finally, tPA^-/- SCN tissue has lower mBDNF levels than WT tissue, while UK122 does not affect mBDNF levels in either strain. Together, these results suggest that either tPA or uPA can support photic/glutamatergic phase shifts of the SCN circadian clock, possibly acting through distinct mechanisms.

Effective treatment with a new protocol using tissue-type plasminogen activator thrombolysis for pump thrombosis with the HVAD device

BACKGROUND:

Pump thrombosis is a major complication of the continuous flow left ventricular assist device. Pump exchange is seen as the therapeutic gold standard. In this study, we report on our experience with using tissue-type plasminogen activator thrombolysis for therapy of pump thrombosis.

METHODS:

We report on our experience with treatment of continuous flow left ventricular assist device pump thrombosis with the HVAD using tissue-type plasminogen activator thrombolysis in nine patients with 16 thrombotic events. In all events we used a uniform treatment protocol.

RESULTS:

All patients presented with a sufficient anticoagulation and had symptoms of heart failure. However, all patients were haemodynamically stable. Six of nine patients presented with a mean arterial pressure above 85 mm Hg and every patient presented with an infection. In all events we achieved short-term success with resolution of the pump thrombosis within a median time of nine hours. Three of nine patients developed recurrent pump thrombosis after >60 days. Besides one case of nonfatal intracranial haemorrhage and one case of minor bleeding, there were no adverse events.

CONCLUSION:

Our data indicates that using a uniform treatment protocol that builds on usage of tissue-type plasminogen activator thrombolysis might be an effective tool for treatment of continuous flow left ventricular assist device pump thrombosis in haemodynamically stable patients. Additionally, our data indicates that infection may be a potential trigger for pump thrombosis.

A Conjugate of Two tPA-Binding RNA Aptamers Efficiently Inhibits Fibrinolysis

Uncontrolled bleeding is a major cause of mortality. Lysine analogues are routinely used in the management of bleeding, but several studies indicate a risk of serious detrimental effects upon their administration. In this study, we report a bivalent conjugate "3218" of two RNA aptamers selected for binding to the serine protease tissue-type plasminogen activator (tPA), the principal initiator of fibrinolysis in mammals. The constituent monomeric aptamers, K32v2 and K18v2, were previously demonstrated to weakly inhibit fibrinolysis. We now show that K32v2 and K18v2 recognize distinct binding sites, presumably in the A- and B-chain of tPA, respectively. Both aptamers bind tPA with low nanomolar affinity and inhibit tPA-mediated activities in a way that is consistent with the proposed localization of their binding sites. The 3218 conjugate possesses the inhibitory activities of both K32v2 and K18v2 and additionally exhibits increased inhibitory efficiency relative to the monomeric aptamers. The 3218 conjugate proved an efficient inhibitor of fibrinolysis and may find application in the management of bleeding as a substitute for, or in combination with, currently used lysine analogues.