Sergio Amaro

Catecholamines, infection, and death in acute ischemic stroke

Experimental studies have recently suggested that acute ischemia may facilitate the appearance of fatal infections as part of a brain-induced immunodepression syndrome. However, the mechanisms and neurological consequences of infections complicating acute ischemic stroke have received much less attention at the bedside. The incidence of infection and death after non-septic stroke was compared in this prospective study with longitudinal changes of cytokines, leukocytes, normetanephrine (NMN) and metanephrine (MN) in 75 consecutive patients. In multivariate analysis, infection, n = 13 (17%), was associated with the upper quartile of MN (OR 3.51, 95% CI 1.30-9.51), neurological impairment (NIHSS) on admission (OR 3.99, 95% CI 1.34-11.8), monocyte count (OR 1.78, 95% CI 1.13-2.79), and increased interleukin (IL)-10 (OR 1.54, 95% CI 1.00-2.38). Mortality at 3 months, n = 16 (21%), was associated with increased levels of NMN on admission (OR 2.34 95% CI 1.15-4.76), NIHSS score (OR 2.57, 95% CI 1.29-5.11), and higher IL-6 levels (OR 1.29, 95% 1.00-1.67). These findings suggest that acute ischemic stroke is associated with an early activation of the sympathetic adrenomedullar pathway that lowers the threshold of infection and increases the risk of death. Moreover, these findings are independent of the blood borne effects of pro- and anti-inflammatory cytokines, and circulating leukocytes.

Uric acid reduces brain damage and improves the benefits of rt-PA in a rat model of thromboembolic stroke

Uric acid is a natural antioxidant that protects the brain in a model of transient focal ischemia in rats. Here we sought to investigate whether uric acid was protective in a model of thromboembolic brain ischemia in rats, and whether the global benefit of recombinant tissue plasminogen activator (rt-PA) was improved by the combined treatment. Adult male Sprague-Dawley rats underwent either ischemia by thromboembolic middle cerebral artery occlusion (MCAO) or sham operation. Uric acid (16 mg/kg) was injected intravenously (i.v.). 20 mins after mCaO, whereas rt-PA (10 mg/kg) was administered i.v. at 3 h. A group of rats received the combined treatment. Rats underwent two neurologic examinations (30 mins and 24 h after MCAO). At 24 h, infarct volume was measured and brain neutrophil infiltration and protein tyrosine nitration were assessed. Treatment with either uric acid or rt-PA reduced infarct volume versus controls (P < 0.05). The protective effect against brain ischemia was greater after cotreatment of uric acid with rt-PA (P < 0.001), which added further benefit to rt-PA alone (P < 0.05). The neurologic score worsened during the first 24 h in treatment controls, whereas it improved in rats receiving uric acid and/or rt-PA. Uric acid strongly reduced ischemia-induced tyrosine nitration, but it was more effective alone than combined with rt-PA, suggesting that reperfusion enhances nitrotyrosine formation. All treatments reduced postischemic brain neutrophil infiltration. These results show that uric acid administered early after thromboembolic stroke is neuroprotective in the rat brain, as it reduces infarct volume, ameliorates the neurologic function, attenuates the inflammatory response, and extends the benefits of rt-PA.

Monocyte subtypes predict clinical course and prognosis in human stroke

The number of circulating monocytes increases after stroke. In this study, we assessed the time course and phenotype of monocyte subsets and their relationship with the clinical course and outcome in 46 consecutive stroke patients and 13 age-matched controls. The proportion of the most abundant ‘classical’ CD14highCD16 monocytes did not change after stroke, whereas that of CD14highCD16+ monocytes increased and CD14dimCD16+ monocytes decreased. CD14highCD16 + monocytes had the highest expression of TLR2, HLA-DR and the angiogenic marker, Tie-2; CD14dimCD16+ monocytes had the highest expression of costimulatory CD86 and adhesion molecule CD49d. Platelet-monocyte interactions were highest in CD14highCD16 monocytes and lowest in CD14dimCD16+ monocytes. In adjusted models, 1/CD14highCD16 monocytes were associated with poor outcome (OR: 1.38), higher mortality (OR: 1.40) and early clinical worsening (OR: 1.29); 2/CD14highCD16+ monocytes were inversely related to mortality (OR: 0.32); and 3/CD14dimCD16+ monocytes were inversely related to poor outcome (OR: 0.74) and infarction size (r= 0.45; P = 0.02). These results illustrate that the predominant monocyte subtype conveys harmful effects after stroke, which include stronger interaction with platelets. Alternatively, rarer subpopulations of monocytes are beneficial with a phenotype that could promote tissue repair and angiogenesis. Therefore, monitoring of monocyte subtypes may emerge as a useful tool at the bedside for stroke patients.

Safety and efficacy of uric acid in patients with acute stroke (URICO-ICTUS): a randomised, double-blind phase 2b/3 trial

INTRODUCTION Uric acid is an antioxidant with neuroprotective effects in experimental models of stroke. We assessed whether uric acid therapy would improve functional outcomes at 90 days in patients with acute ischaemic stroke. METHODS URICO-ICTUS was a randomised, double-blind, placebo-controlled, phase 2b/3 trial that recruited patients with acute ischaemic stroke admitted to ten Spanish stroke centres. Patients were included if they were aged 18 years or older, had received alteplase within 4·5 h of symptom onset, and had an eligible National Institutes of Health Stroke Scale (NIHSS) score (>6 and ≤25) and premorbid (assessed by anamnesis) modified Rankin Scale (mRS) score (≤2). Patients were randomly allocated (1:1) to receive uric acid 1000 mg or placebo (both infused intravenously in 90 min during the infusion of alteplase), stratified by centre and baseline stroke severity. The primary outcome was the proportion of patients with excellent outcome (ie, an mRS score of 0-1, or 2 if premorbid score was 2) at 90 days, analysed in the target population (all randomly assigned patients who had been correctly diagnosed with ischaemic stroke and had begun study medication). The study is registered with ClinicalTrials.gov, number NCT00860366. FINDINGS Between July 1, 2011, and April 30, 2013, we randomly assigned 421 patients, of whom 411 (98%) were included in the target population (211 received uric acid and 200 received placebo). 83 (39%) patients who received uric acid and 66 (33%) patients who received placebo had an excellent outcome (adjusted risk ratio 1·23 [95% CI 0·96-1·56]; p=0·099). No clinically relevant or statistically significant differences were reported between groups with respect to death (28 [13%] patients who received uric acid vs 31 [16%] who received placebo), symptomatic intracerebral haemorrhage (nine [4%] vs six [3%]), and gouty arthritis (one [<1%] vs four [2%]). 516 adverse events occurred in the uric acid group and 532 in the placebo group, of which 61 (12%) and 67 (13%), respectively, were serious adverse events (p=0·703). INTERPRETATION The addition of uric acid to thrombolytic therapy did not increase the proportion of patients who achieved excellent outcome after stroke compared with placebo, but it did not lead to any safety concerns. FUNDING Institute of Health Carlos III of the Spanish Ministry of Health and Fundación Doctor Melchor Colet.

A Pilot Study of Dual Treatment With Recombinant Tissue Plasminogen Activator and Uric Acid in Acute Ischemic Stroke

Background and Purpose— Uric acid (UA) increases the neuroprotective effects of recombinant tissue plasminogen activator (rt-PA) in experimental ischemia. In patients with stroke, increased UA levels have been linked to better stroke recovery, but the clinical safety of dual administration of UA and rt-PA is unknown. Methods— Using a double-blind design, we assessed the safety of exogenous UA in patients with acute stroke treated with rt-PA. Patients were randomized to an intravenous solution of 500 mL of 5% mannitol/0.1% lithium carbonate (vehicle group, n=8) or 500 or 1000 mg of UA (n=16). Safety end points at day 90, lipid peroxidation (serum malondialdehyde), and serum kinetics of UA were established. Results— Twenty-four patients with stroke were treated with rt-PA within mean (SD) 133 (35) minutes of clinical onset (admission National Institutes of Health Stroke Scale score mean [SD] 11 [7], age 71 [10.6] years, 71% males). Levels of UA decreased in the vehicle group and increased for approximately 24 hours in the high dose of UA group, which also had lower levels of malondialdehyde at day 5. Mortality (12.5%), symptomatic central nervous system bleeding (0%), and outcome at day 90 were similar in the 3 treatment arms; one patient in the high-dose group had a mild gouty episode. Conclusions— The administration of UA appears to be safe, decreases lipid peroxidation, and prevents an early fall of UA in serum in patients treated with rt-PA within 3 hours of stroke onset. The clinical efficacy of dual administration of exogenous UA and rt-PA deserves further investigation in a larger acute stroke trial.

Interleukin 10, monocytes and increased risk of early infection in ischaemic stroke

Background and purpose: : The pathophysiology of stroke-associated infection (SAI) is uncertain. The cytokine profile and peripheral white cell response were assessed in patients with or without SAI. Methods: The incidence of SAI was assessed in 110 patients with ischaemic stroke allocated antibiotic prophylaxis or placebo within 24 h of clinical onset. Peripheral white cell counts, interleukin (IL)6, tumour necrosis factor (TNF)α and IL10 were measured in plasma. Results: 17 (15%) patients developed infection and showed time-dependent increases of total white cell count, neutrophils, monocytes, lymphocytes, IL6 and IL10, whereas TNFα and the TNFα/IL10 ratio decreased. In logistic regression, IL10 (odds ratio (OR) 1.08, 95% confidence interval (CI) 1.01 to 1.16), monocyte count (OR 1.42, 95% CI 1.08 to 1.87) and National Institute for Health Stroke Survey score on admission (OR 1.17, 95% CI 1.05 to 1.31) were independent predictors of systemic infection. Conclusions: SAI is associated with stroke severity, excessive IL10-mediated response and an increased number of circulating monocytes. These results support the finding that acute ischaemic brain injury triggers a blood-borne anti-inflammatory response that decreases the antimicrobial drive of the immune system.

Uric Acid Levels Are Relevant in Patients With Stroke Treated With Thrombolysis

Background and Purpose— Uric acid (UA) is a neuroprotective antioxidant that improves the benefits of alteplase in experimental ischemia. However, it is unknown whether endogenous UA also influences the response to thrombolysis in patients with stroke. Methods— A total of 317 consecutive patients treated with thrombolysis were included in a prospective stroke registry. Demographics, laboratory data, neurological course, and infarction volume were prospectively collected. Excellent outcome was defined as achieving a modified Rankin Scale score <2 at 90 days. Binary and ordinal logistic regression models were used to analyze modified Rankin Scale score at 90 days. Results— UA levels were significantly higher in patients with an excellent outcome than in patients with a poor outcome (5.82 [1.39] versus 5.42 [1.81], P=0.029). In multivariate models, increased UA levels (OR, 1.23; 95% CI, 1.03 to 1.49; P=0.025) were associated with an excellent outcome and with an increased risk of shifting to a better category across the modified Rankin Scale (OR, 1.19; 95% CI, 1.04 to 1.38; P=0.014) independently of the effect of confounders. The levels of UA and the volume of final infarction were inversely correlated (r=−0.216, P<0.001) and the inverse correlation remained after adjustment for age, sex, and baseline National Institutes of Health Stroke Scale score (t value=−2.54, P=0.01). Significantly lower UA levels were found in patients with malignant middle cerebral artery infarction and parenchymal hemorrhage postthrombolysis. Conclusions— Increased UA serum levels are associated with better outcome in patients with stroke treated with reperfusion therapies. These results support the assessment of the potential neuroprotective role of the exogenous administration of UA in patients with stroke treated with thrombolysis.

Translational Stroke Research of the Combination of Thrombolysis and Antioxidant Therapy

Stroke is an enormous public health problem with an imperative need for more effective therapy. Recombinant tissue plasminogen activator is the only licensed drug for acute stroke, but its efficacy may be limited by the toxicity of the compound and by reperfusion injury. The coadministration of neuroprotective drugs could augment the value of thrombolytic therapy, but the evidence in support of this approach is scarce. The use of the free radical trapping NXY-059, either with or without recombinant tissue plasminogen activator, was not successful in Phase III studies. However, these results could reflect its weak antioxidant capacity, poor blood–brain barrier penetration, and lack of synergism with recombinant tissue plasminogen activator as well as the overly broad treatment window used in the reported trials. This article contends that further translational research should explore newer antioxidant drugs in combination with thrombolytic agents, but only if the combination yields additive or synergistic effects in preclinical thromboembolic models or in biomarker-assisted Phase II studies. Edaravone and novel nitrones endowed with a better pharmacokinetic profile or multitarget and thrombolytic activity are discussed as well as the latest research data on uric acid, a strong endogenous antioxidant in blood that is early consumed after acute stroke. The coadministration of uric acid and recombinant tissue plasminogen activator has shown to provide synergistic neuroprotection in experimental thromboembolic models and to lessen several biomarkers of oxidative stress in patients with acute stroke. The clinical efficacy of uric acid is currently under investigation in a Phase III trial that follows current recommendations of also evaluating surrogate biomarkers of treatment effects.

Oral anticoagulant-associated intracerebral hemorrhage

The incidence of oral anticoagulation-associated intracerebral hemorrhage (OAC-ICH) is growing due to the increasing use of warfarin and the older age of treated patients. Recent population studies reveal that OAC-ICH currently occurs at a frequency comparable to that of subarachnoid hemorrhage. Most frequently, OAC-ICH are located in deep or lobar regions of the brain, although it may also occur in the brainstem. These hemorrhages are larger than spontaneous hematomas and may be fatal in at least 50% of cases. The primary cause of brain injury in patients with OAC-ICH is the direct mechanical disruption of the brain tissue but secondary damage may occur through the intervention of matrix metalloproteinases, glutamate, cytokines, heme, iron, and the chemical toxicity of products such as thrombin, which are released from the clot. The pathogenesis of OAC-ICH also includes the effects of aging, the level of anticoagulation, genetic factors, and a high prevalence of concurrent cerebrovascular conditions, such as cerebral amyloid angiopathy, leukoaraiosis or previous strokes. The treatment of OAC-ICH is challenging and involves rapid reversal of anticoagulation with hemostatic drug therapies such as vitamin K, fresh frozen plasma, prothrombin complex concentrates or recombinant factor VIIa. These therapies may not always be sufficient to stabilize the patient’s clinical condition and lacking randomized controlled trials, the best hematological approach to reverse oral anticoagulation is debated. Other difficult decisions reviewed in this article are whether anticoagulation should be restarted after OAC-ICH, and when anticoagulant treatment should be resumed. The newer oral anticoagulants, which are increasingly being introduced for thromboembolism prevention, may confer a lower risk of intracranial bleeding than warfarin, although they do not have an antidote and their anticoagulant effect is difficult to monitor.

Single-Center Experience of Cerebral Artery Thrombectomy Using the TREVO Device in 60 Patients With Acute Ischemic Stroke

Background and Purpose— We sought to explore the safety and efficacy of the new TREVO stent-like retriever in consecutive patients with acute stroke. Methods— We conducted a prospective, single-center study of 60 patients (mean age, 71.3 years; male 47%) with stroke lasting <8 hours in the anterior circulation (n=54) or <12 hours in the vertebrobasilar circulation (n=6) treated if CT perfusion/CT angiography confirmed a large artery occlusion, ruled out a malignant profile, or showed target mismatch if symptoms >4.5 hours. Successful recanalization (Thrombolysis In Cerebral Infarction 2b–3), good outcome (modified Rankin Scale score 0–2) and mortality at Day 90, device-related complications, and symptomatic hemorrhage (parenchymal hematoma Type 1 or parenchymal hematoma Type 2 and National Institutes of Health Stroke Scale score increment ≥4 points) were prospectively assessed. Results— Median (interquartile range) National Institutes of Health Stroke Scale score on admission was 18 (12–22). The median (interquartile range) time from stroke onset to groin puncture was 210 (173–296) minutes. Successful revascularization was obtained in 44 (73.3%) of the cases when only the TREVO device was used and in 52 (86.7%) when other devices or additional intra-arterial tissue-type plasminogen activator were also required. The median time (interquartile range) of the procedure was 80 (45–114) minutes. Good outcome was achieved in 27 (45%) of the patients and the mortality rate was 28.3%. Seven patients (11.7%) presented a symptomatic intracranial hemorrhage. No other major complications were detected. Conclusions— The TREVO device was reasonably safe and effective in patients with severe stroke. These results support further investigation of the TREVO device in multicentric registries and randomized clinical trials.