Perttu J. Lindsberg

Inflammation and Infections as Risk Factors for Ischemic Stroke

Background— Inflammatory processes have fundamental roles in stroke in both the etiology of ischemic cerebrovascular disease and the pathophysiology of cerebral ischemia. We summarize clinical data on infection and inflammation as risk or trigger factors for human stroke and investigate current evidence for the hypothesis of a functional interrelation between traditional risk factors, genetic predisposition, and infection/inflammation in stroke pathogenesis. Summary of Review— Several traditional vascular risk factors are associated with proinflammatory alterations, including leukocyte activation, and predispose cerebral vasculature to thrombogenesis on inflammatory stimulation. Furthermore, accumulation of inflammatory cells, mainly monocytes/macrophages, within the vascular wall starts early during atherogenesis. During later disease stages, their activation can lead to plaque rupture and thrombus formation, increasing stroke risk. Inflammatory markers (eg, leukocytes, fibrinogen, C-reactive protein) are independent predictors of ischemic stroke. Chronic infections (eg, infection with Chlamydia pneumoniae or Helicobacter pylori) were found to increase the risk of stroke; however, study results are at variance, residual confounding is not excluded, and causality is not established at present. In case-control studies, acute infection within the preceding week was a trigger factor for ischemic stroke. Acute and exacerbating chronic infection may act by activating coagulation and chronic infections and may contribute to atherogenesis. Genetic predisposition of the inflammatory host response may be an important codeterminant for atherogenesis and stroke risk. Conclusions— Inflammation contributes to stroke risk via various interrelated mechanisms. Infectious diseases, traditional risk factors, and genetic susceptibility may cooperate in stimulating inflammatory pathways. Final proof of a causal role of infectious/inflammatory mechanisms in stroke pathogenesis is still lacking and will require interventional studies.

Therapy of Basilar Artery Occlusion A Systematic Analysis Comparing Intra-Arterial and Intravenous Thrombolysis

Background and Purpose— Basilar artery occlusion (BAO) is an infrequent form of acute stroke, which invariably leads to death or long-term disability if not recanalized. A traditional recanalization approach based on historical controls and pathophysiological consideration is local intra-arterial thrombolysis (IAT) in eligible patients. This necessitates diagnostic evaluation and treatment in stroke centers equipped with an interventional neuroradiological service on a 24-hour basis, but its superiority to the technically simple intravenous thrombolysis (IVT) remains unproven. Methods— We analyzed systematically published case series of substantial size reporting the outcome of BAO after IAT or IVT. Results— In 420 BAO patients treated with IVT (76) and IAT (344), death or dependency were equally common: 78% (59 of 76) and 76% (260 of 344), respectively (P=0.82). Recanalization was achieved more frequently with IAT (225 of 344; 65%) than with IVT (40 of 76; 53%; P=0.05), but survival rates after IVT (38 of 76; 50%) and IAT (154 of 344; 45%) were equal (P=0.48). A total of 24% of patients treated with IAT and 22% treated with IVT reached good outcomes (P=0.82). Without recanalization, the likelihood of good outcome was close to nil (2%). Conclusions— Recanalization occurs in more than half of BAO patients treated with IAT or IVT, and 45% to 55% of survivors regain functional independence. Although improved therapy forms for BAO are necessary, hospitals not equipped for IAT may set up IVT protocols. The effect of IVT is probably not much different from the effect of IAT. IVT represents probably the best treatment that can be offered to victims of acute BAO in such hospitals.

Reducing in-hospital delay to 20 minutes in stroke thrombolysis

Objectives: Efficacy of thrombolytic therapy for ischemic stroke decreases with time elapsed from symptom onset. We analyzed the effect of interventions aimed to reduce treatment delays in our single-center observational series. Methods: All consecutive ischemic stroke patients treated with IV alteplase (tissue plasminogen activator [tPA]) were prospectively registered in the Helsinki Stroke Thrombolysis Registry. A series of interventions to reduce treatment delays were implemented over the years 1998 to 2011. In-hospital delays were analyzed as annual median door-to-needle time (DNT) in minutes, with interquartile range. Results: A total of 1,860 patients were treated between June 1995 and June 2011, which included 174 patients with basilar artery occlusion (BAO) treated mostly beyond 4.5 hours from symptom onset. In the non-BAO patients, the DNT was reduced annually, from median 105 minutes (65–120) in 1998, to 60 minutes (48–80) in 2003, further on to 20 minutes (14–32) in 2011. In 2011, we treated with tPA 31% of ischemic stroke patients admitted to our hospital. Of these, 94% were treated within 60 minutes from arrival. Performing angiography or perfusion imaging doubled the in-hospital delays. Patients with in-hospital stroke or arriving very soon from symptom onset had longer delays because there was no time to prepare for their arrival. Conclusions: With multiple concurrent strategies it is possible to cut the median in-hospital delay to 20 minutes. The key is to do as little as possible after the patient has arrived at the emergency room and as much as possible before that, while the patient is being transported.

A candidate gene for developmental dyslexia encodes a nuclear tetratricopeptide repeat domain protein dynamically regulated in brain

Approximately 3–10% of people have specific difficulties in reading, despite adequate intelligence, education, and social environment. We report here the characterization of a gene, DYX1C1 near the DYX1 locus in chromosome 15q21, that is disrupted by a translocation t(2;15)(q11;q21) segregating coincidentally with dyslexia. Two sequence changes in DYX1C1, one involving the translation initiation sequence and an Elk-1 transcription factor binding site (–3G → A) and a codon (1249G → T), introducing a premature stop codon and truncating the predicted protein by 4 aa, associate alone and in combination with dyslexia. DYX1C1 encodes a 420-aa protein with three tetratricopeptide repeat (TPR) domains, thought to be protein interaction modules, but otherwise with no homology to known proteins. The mouse Dyx2016 protein is 78% identical to the human protein, and the nonhuman primates differ at 0.5–1.4% of residues. DYX1C1 is expressed in several tissues, including the brain, and the protein resides in the nucleus. In human brain, DYX1C1 protein localizes to a fraction of cortical neurons and white matter glial cells. We conclude that DYX1C1 should be regarded as a candidate gene for developmental dyslexia. Detailed study of its function may open a path to understanding a complex process of development and maturation of the human brain.

Treatment and outcomes of acute basilar artery occlusion in the Basilar Artery International Cooperation Study (BASICS): a prospective registry study.

BACKGROUND Treatment strategies for acute basilar artery occlusion (BAO) are based on case series and data that have been extrapolated from stroke intervention trials in other cerebrovascular territories, and information on the efficacy of different treatments in unselected patients with BAO is scarce. We therefore assessed outcomes and differences in treatment response after BAO. METHODS The Basilar Artery International Cooperation Study (BASICS) is a prospective, observational registry of consecutive patients who presented with an acute symptomatic and radiologically confirmed BAO between November 1, 2002, and October 1, 2007. Stroke severity at time of treatment was dichotomised as severe (coma, locked-in state, or tetraplegia) or mild to moderate (any deficit that was less than severe). Outcome was assessed at 1 month. Poor outcome was defined as a modified Rankin scale score of 4 or 5, or death. Patients were divided into three groups according to the treatment they received: antithrombotic treatment only (AT), which comprised antiplatelet drugs or systemic anticoagulation; primary intravenous thrombolysis (IVT), including subsequent intra-arterial thrombolysis; or intra-arterial therapy (IAT), which comprised thrombolysis, mechanical thrombectomy, stenting, or a combination of these approaches. Risk ratios (RR) for treatment effects were adjusted for age, the severity of neurological deficits at the time of treatment, time to treatment, prodromal minor stroke, location of the occlusion, and diabetes. FINDINGS 619 patients were entered in the registry. 27 patients were excluded from the analyses because they did not receive AT, IVT, or IAT, and all had a poor outcome. Of the 592 patients who were analysed, 183 were treated with only AT, 121 with IVT, and 288 with IAT. Overall, 402 (68%) of the analysed patients had a poor outcome. No statistically significant superiority was found for any treatment strategy. Compared with outcome after AT, patients with a mild-to-moderate deficit (n=245) had about the same risk of poor outcome after IVT (adjusted RR 0.94, 95% CI 0.60-1.45) or after IAT (adjusted RR 1.29, 0.97-1.72) but had a worse outcome after IAT compared with IVT (adjusted RR 1.49, 1.00-2.23). Compared with AT, patients with a severe deficit (n=347) had a lower risk of poor outcome after IVT (adjusted RR 0.88, 0.76-1.01) or IAT (adjusted RR 0.94, 0.86-1.02), whereas outcomes were similar after treatment with IAT or IVT (adjusted RR 1.06, 0.91-1.22). INTERPRETATION Most patients in the BASICS registry received IAT. Our results do not support unequivocal superiority of IAT over IVT, and the efficacy of IAT versus IVT in patients with an acute BAO needs to be assessed in a randomised controlled trial. FUNDING Department of Neurology, University Medical Center Utrecht.

Nuclear Factor-κB Contributes to Infarction After Permanent Focal Ischemia

Background and Purpose— Activation of transcription factor nuclear factor-&kgr;B (NF-&kgr;B) may induce expression of either proinflammatory/apoptotic genes or antiapoptotic genes. Because a considerable number of middle cerebral artery occlusions (MCAOs) in humans are not associated with reperfusion during the first 24 hours, the role of NF-&kgr;B after permanent MCAO (pMCAO) was investigated. Methods— Mice transgenic for a NF-&kgr;B–driven &bgr;-globin reporter were exposed to pMCAO, and the expression of the reporter gene was quantified with real-time polymerase chain reaction. Mice lacking the p50 subunit of NF-&kgr;B and wild-type controls were exposed to pMCAO with or without treatment with pyrrolidinedithiocarbamate (PDTC), an NF-&kgr;B inhibitor. Brain sections of human stroke patients were immunostained for the activated NF-&kgr;B. Results— pMCAO increased NF-&kgr;B transcriptional activity to 260% (36.9±4.5 compared with 14.4±2.6; n=10; P <0.01) in the brain; this NF-&kgr;B activation was completely blocked by PDTC (17.2±2.6; n=9; P <0.05). In p50−/− mice, pMCAO resulted in 41% (18±3.2 mm3; n=12) smaller infarcts compared with wild-type controls (32.9±3.8 mm3; n=9; P <0.05), which was comparable to the protection achieved with PDTC in wild-type mice (19.6±4.2 mm3; n=8). Pro-DTC, a PDTC analogue that does not cross the blood-brain barrier, had no effect, even though Pro-DTC and PDTC were equally protective in vitro. During the first 2 days of human stroke, NF-&kgr;B was activated in neurons in the penumbral areas. Conclusions— NF-&kgr;B is induced in neurons during human stroke, and activation of NF-&kgr;B in the brain may contribute to infarction in pMCAO.

Endothelial ICAM-1 Expression Associated With Inflammatory Cell Response in Human Ischemic Stroke

BACKGROUND After focal brain ischemia, leukocytes adhere to the perturbed endothelium and are believed to aggravate reperfusion injury. Although ischemia-induced upregulation of endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and P-selectin, has been observed in experimental animals, the mechanism of cerebral leukocyte infiltration and thus therapeutic possibilities to reduce it in humans are uncertain. METHODS AND RESULTS We counted the granulocytes, mononuclear phagocytes, and the percentages of cerebral microvessels expressing ICAM-1 by applying immunohistochemistry on brain sections showing a variable degree of neuronal damage from 11 human subjects who died 15 hours to 18 days after ischemic stroke and from normal control brains. In infarcted regions, granulocytes were detected as early as at 15 hours after injury (11.3 versus 0.5 cells/mm2 in noninfarcted hemisphere); their amount exceeded 200 cells/mm2 by 2.2 days but was back to normal level at 6.3 and 8.5 days. Acute infarctions (0.6 to 8.5 days) harbored significantly more ICAM-1-stained microvessels (up to 97% of microvessels at 1.8 days) than the noninfarcted hemisphere (P < .001), although the noninfarcted hemisphere (1.8 to 6.3 days) also showed higher ICAM-1 expression than controls. In the absence of ICAM-1 upregulation, macrophages (> 200/mm2) were abundant in the core of neuronal damage at 17 and 18 days. CONCLUSIONS The striking upregulation of endothelial ICAM-1 expression, functioning in concert with chemotactic factors, may cause granulocyte infiltration during the first 3 days after stroke. This study may support the usage and timing of antibody infusions to block endothelial adhesion molecules in an attempt to reduce leukocyte-induced damage in stroke.

Thrombolysis in very elderly people: controlled comparison of SITS International Stroke Thrombolysis Registry and Virtual International Stroke Trials Archive

Objective To assess effect of age on response to alteplase in acute ischaemic stroke. Design Adjusted controlled comparison of outcomes between non-randomised patients who did or did not undergo thrombolysis. Analysis used Cochran-Mantel-Haenszel test and proportional odds logistic regression analysis. Setting Collaboration between International Stroke Thrombolysis Registry (SITS-ISTR) and Virtual International Stroke Trials Archive (VISTA). Participants 23 334 patients from SITS-ISTR (December 2002 to November 2009) who underwent thrombolysis and 6166 from VISTA neuroprotection trials (1998-2007) who did not undergo thrombolysis (as controls). Of the 29 500 patients (3472 aged >80 (“elderly,” mean 84.6), data on 272 patients were missing for baseline National Institutes of Health stroke severity score, leaving 29 228 patients for analysis adjusted for age and baseline severity. Main outcome measures Functional outcomes at 90 days measured by score on modified Rankin scale. Results Median severity at baseline was the same for patients who underwent thrombolysis and controls (median baseline stroke scale score: 12 for each group, P=0.14; n=29 228). The distribution of scores on the modified Rankin scale was better among all thrombolysis patients than controls (odds ratio 1.6, 95% confidence interval 1.5 to 1.7; Cochran-Mantel-Haenszel P<0.001). The association occurred independently among patients aged ≤80 (1.6, 1.5 to 1.7; P<0.001; n=25 789) and in those aged >80 (1.4, 1.3 to 1.6; P<0.001; n=3439). Odds ratios were consistent across all 10 year age ranges above 30, and benefit was significant from age 41 to 90; dichotomised outcomes (score on modified Rankin scale 0-1 v 2-6; 0-2 v 3-6; and 6 (death) v rest) were consistent with the results of the ordinal analysis. Conclusions Outcome in patients with acute ischaemic stroke is significantly better in those who undergo thrombolysis compared with those who do not. Increasing age is associated with poorer outcome but the association between thrombolysis treatment and improved outcome is maintained in very elderly people. Age alone should not be a barrier to treatment.

Nitric Oxide in the Central Nervous System

The majority of the data on nitric oxide (NO) in the central nervous system (CNS) relies on histochemical and immunohistochemical evidence concerning the distribution of the nitric oxide synthase (NOS), its inhibition by specific antagonists and its co-localization with the receptor enzyme guanylate cyclase (GC) in the same functional region. All three isoforms, endothelial (eNOS), neural (nNOS) and macrophage type inducible (iNOS), are of importance to the normal and pathological function of the CNS. In nNOS gene deleted mice eNOS seems to contribute to the maintenance of neuronal function. NO may contribute to synaptic plasticity as a retrograde mediator that is released by postsynaptic NMDA-receptor activation. Microglia contains membrane-bound inducible iNOS that may be important in host defence function. Glia and pericytes surrounding the blood vessels contain GC that is stimulated by NO released from endothelium and nerve endings. Excessive production of highly reactive NO may be responsible for the neurotoxicity mediated by NMDA receptors that contributes to the symptomatology of strokes and neurodegenerative diseases. Moreover, after initial stimulation by cytokines, large amounts of NO produced by iNOS in the microglia (brain-based macrophages) may cause cellular damage.

Off-Label Thrombolysis Is Not Associated With Poor Outcome in Patients With Stroke

Background and Purpose— Numerous contraindications included in the license of alteplase, most of which are not based on scientific evidence, restrict the portion of patients with acute ischemic stroke eligible for treatment with alteplase. We studied whether off-label thrombolysis was associated with poorer outcome or increased rates of symptomatic intracerebral hemorrhage compared with on-label use. Methods— All consecutive patients with stroke treated with intravenous thrombolysis from 1995 to 2008 at the Helsinki University Central Hospital were registered (n=1104). After excluding basilar artery occlusions (n=119), the study population included 985 patients. Clinical outcome (modified Rankin Scale 0 to 2 versus 3 to 6) and symptomatic intracerebral hemorrhage according to 3 earlier published criteria were analyzed with a logistic regression model adjusting for 21 baseline variables. Results— One or more license contraindications to thrombolysis was present in 51% of our patients (n=499). The most common of these were age >80 years (n=159), mild stroke National Institutes of Health Stroke Scale score <5 (n=129), use of intravenous antihypertensives prior to treatment (n=112), symptom-to-needle time >3 hours (n=95), blood pressure >185/110 mm Hg (n=47), and oral anticoagulation (n=39). Age >80 years was the only contraindication independently associated with poor outcome (OR, 2.18; 95% CI, 1.27 to 3.73) in the multivariate model. None of the contraindications were associated with an increased risk of symptomatic intracerebral hemorrhage. Conclusions— Off-license thrombolysis was not associated with poorer clinical outcome, except for age >80 years, nor with increased rates of symptomatic intracerebral hemorrhage. The current extensive list of contraindications should be re-evaluated when data from ongoing randomized trials and observational studies become available.