Retrospective review COVID-19 vaccine induced thrombotic thrombocytopenia and cerebral venous thrombosis-what can we learn from the immune response.

INTRODUCTION: Cerebral Venous Thrombosis (CVT), prior to the COVID pandemic, was rare representing 0.5 of all strokes, with the diagnosis made by MRI or CT venography.1-,3 COVID-19 patients compared to general populations have a 30-60 times greater risk of CVT compared to non-affected populations, and up to a third of severe COVID patients may have thrombotic complications.4-8 Currently, vaccines are the best way to prevent severe COVID-19. In February 2021, reports of CVT and Vaccine-induced immune thrombotic thrombocytopenia (VITT) related to adenovirus viral vector vaccines including the Oxford-AstraZeneca vaccine (AZD1222 (ChAdOx1)) and Johnson & Johnson COVID-19 vaccine (JNJ-78436735 (Ad26.COV2·S)), were noted, with a 1/583,000 incidence from Johnson and Johnson vaccine in the United States.11, 12 This study retrospectively analyzed CVT and cross-sectional venography at an Eastern Medical Center from 2018 to 2021, and presents radiographic examples of CVT and what is learned from the immune response. METHODS: After IRB approval, a retrospective review of cross-sectional CTV and MRVs from January 1st 2018 to April 30th 2021, at a single health system was performed. Indications, vaccine status, patient age, sex, and positive finding incidence were specifically assessed during March and April for each year. A multivariable-adjusted trends analysis using Poisson regression estimated venogram frequencies and multivariable logistic regression compared sex, age, indications and vaccination status. RESULTS AND DISCUSSION: From January 1, 2018 to April 30, 2021, (Fig. 1), a total of n = 2206 in patient and emergency room cross-sectional venograms were obtained, with 322 CTVs and 1884 MRVs. In 2018, 2019, 2020, respective totals of cross-sectional venograms were 568, 657, 660, compared to 321 cross-sectional venograms in the first four months of 2021. CTV in 2018, 2019, 2020, respective totals were 51, 86, 97, MRV totals were 517, 571, 563, compared to the 2021 first four month totals of 88 CTVs and 233 MRVs. March, April 2018, 2019, 2020, CTVs respectively were 6, 17, 11, compared to the 2021 first four months of 59 CTVs, comprising 63% of the total 93 CTVs, respective MRVs were 79, 97, 52, compared to 143 MRVs in the first four months of 2021 for 39% of the total 371 MRVs. In March, April 2020 during the pandemic onset, cross-sectional imaging at the East Coast Medical Center decreased, as priorities were on maintaining patient ventilation, high level of care and limiting spread of disease. In March/April 2021, reports of VITT and CVT likely contributed to increased CTVs and MRVs, of 39.65% [1.20-1.63] increase (P < 0.001) from prior. In March, April 2021 of 202 venograms obtained, 158 (78.2.%) were unvaccinated patients, 16 positive for CVT (10.1%), 44 were on vaccinated patients (21.7%), 8 specifically ordered with vaccination as a clinical indication, 2 positive for CVT (4.5%), (odds ratio = 0.52 [0.12-2.38], p = 0.200). CONCLUSION: CTV prior to the COVID pandemic, was rare, responsible for 0.5 of all strokes, at the onset of the pandemic in the East Coast, overall cross-sectional imaging volumes declined due to maintaining ventilation, high levels of care and limiting disease spread, although COVID-19 patients have a 30-60 times greater risk of CVT compared to the general population, and vaccination is currently the best option to mitigate severe disease. In early 2021, reports of adenoviral vector COVID vaccines causing CTV and VITT, led to at 39.65% increase in cross-sectional venography, however, in this study unvaccinated patients in 2021 had higher incidence of CVT (10.1%), compared to the vaccinated patients (4.5%). Clinicians should be aware that VITT CVT may present with a headache 5-30 days post-vaccination with thrombosis best diagnosed on CTV or MRV. If thrombosis is present with thrombocytopenia, platelets <150 × 109, elevated D-Dimer >4000 FEU, and positive anti-PF4 ELISA assay, the diagnosis is definitive.13 VITT CVT resembles spontaneous autoimmune heparin induced thrombocytopenia (HIT), and is postulated to occur from platelet factor 4 (PF4) binding to vaccine adenoviral vectors forming a novel antigen, anti-PF4 memory B-cells and anti-PF4 (VITT) antibodies.14-17.

Neutrophils predominate the immune signature of cerebral thrombi in COVID-19 stroke patients.

Coronavirus disease 2019 (COVID-19) is associated with an increased risk of thrombotic events. Ischemic stroke in COVID-19 patients entails high severity and mortality rates. Here we aimed to analyze cerebral thrombi of COVID-19 patients with large vessel occlusion (LVO) acute ischemic stroke to expose molecular evidence for SARS-CoV-2 in the thrombus and to unravel any peculiar immune-thrombotic features. We conducted a systematic pathological analysis of cerebral thrombi retrieved by endovascular thrombectomy in patients with LVO stroke infected with COVID-19 (n = 7 patients) and non-covid LVO controls (n = 23). In thrombi of COVID-19 patients, the SARS-CoV-2 docking receptor ACE2 was mainly expressed in monocytes/macrophages and showed higher expression levels compared to controls. Using polymerase chain reaction and sequencing, we detected SARS-CoV-2 Clade20A, in the thrombus of one COVID-19 patient. Comparing thrombus composition of COVID-19 and control patients, we noted no overt differences in terms of red blood cells, fibrin, neutrophil extracellular traps (NETs), von Willebrand Factor (vWF), platelets and complement complex C5b-9. However, thrombi of COVID-19 patients showed increased neutrophil density (MPO+ cells) and a three-fold higher Neutrophil-to-Lymphocyte Ratio (tNLR). In the ROC analysis both neutrophils and tNLR had a good discriminative ability to differentiate thrombi of COVID-19 patients from controls. In summary, cerebral thrombi of COVID-19 patients can harbor SARS-CoV2 and are characterized by an increased neutrophil number and tNLR and higher ACE2 expression. These findings suggest neutrophils as the possible culprit in COVID-19-related thrombosis.

Pathogeny of cerebral venous thrombosis in SARS-Cov-2 infection: Case reports.

RATIONALE: Pathogeny of thrombosis in COVID-19 is related to interaction of SARS-Cov-2 with vascular wall through the angiotensin converting enzyme 2 (ACE2) receptor. This induces 2 pathways with immunothrombosis from activated endothelium (cytokine storm, leukocyte and platelet recruitment, and activation of coagulation extrinsic pathway), and rise of angiotensin II levels promoting inflammation. While thrombosis is widely described in COVID-19 patients admitted in intensive care unit, cerebrovascular diseases remains rare, in particular cerebral venous thrombosis (CVT). PATIENT CONCERNS: We describe 2 cases of women admitted during the spring of 2020 for intracranial hypertension signs, in stroke units in Great-east, a French area particularly affected by COVID-19 pandemia. DIAGNOSES: Cerebral imaging revealed extended CVT in both cases. The first case described was more serious due to right supratentorial venous infarction with hemorrhagic transformation leading to herniation. Both patients presented typical pneumonia due to SARS-Cov-2 infection, confirmed by reverse transcription polymerase chain reaction on a nasopharyngeal swab in only one. INTERVENTIONS: The first patient had to undergo decompressive craniectomy, and both patients were treated with anticoagulation therapy. OUTCOMES: Favorable outcome was observed for 1 patient. Persistent coma, due to bi thalamic infarction, remained for the other with more serious presentation. LESSONS: CVT, as a serious complication of COVID-19, has to be searched in all patients with intracranial hypertension syndrome. Data about anticoagulation therapy to prevent such serious thrombosis in SARS-Cov-2 infection are lacking, in particular in patients with mild and moderate COVID-19.

Thrombo-inflammation in acute ischaemic stroke - implications for treatment.

Ischaemic stroke elicits a strong neuroinflammatory response, but the functional relevance and therapeutic potential of neuroinflammation has only recently become apparent. In acute experimental stroke, T cells contribute to ischaemia-reperfusion injury after recanalization in an antigen-independent manner. Surprisingly, the detrimental T cell effects are platelet-dependent. Glycoprotein (GP)Ib-mediated and GPVI-mediated platelet activation, but not GPIIb-IIIa-mediated platelet aggregation, is an important checkpoint that orchestrates thrombotic and pro-inflammatory pathways, and downstream activation of coagulation factor XII is a driving force of ischaemia-reperfusion injury in acute stroke. The evidence therefore suggests that T cells interact with platelets and facilitate further infarct development through a complex process that we refer to as thrombo-inflammation. Results of clinical trials of agents that target lymphocytes support this concept. However, in the majority of patients with ischaemic stroke, recanalization cannot be achieved and the contribution of T cells in the setting of the resultant permanent ischaemia and subacute stroke is less clear and more complex. In some settings, T cells still seem to aggravate neuronal damage late after the ischaemic insult, but stroke triggers systemic immunodepression, therefore further anti-inflammatory treatments would need to be used carefully in this context. Targeting stroke-related neuroinflammation could become an effective adjunct therapy to improve outcomes after ischaemic stroke, but this approach will require caution regarding the timing and avoidance of adverse effects.

Circulating Levels of Interleukin-10 and -17 in Patients with Cerebral Sinovenous Thrombosis (CSVT) in Acute and Subacute Stages: A Prospective Case-Control Study.

BACKGROUND: Cerebral sinovenous thrombosis (CSVT) is a neurovascular disorder that occurs when a blood clot develops in a vein near the brain. Evaluating the subsequent changes in inflammatory cytokines can better reveal the underlying pathogeneses. OBJECTIVE: To assess the serum levels of interleukin-10 (an anti-inflammatory cytokine) and IL-17 (a pro-inflammatory cytokine) in patients with aseptic non-vasculitic CSVT. METHODS: In this prospective case-control study, 31 patients with aseptic non-vasculitic CSVT (admitted in Namazi Hospital, Shiraz University of Medical Sciences, Shiraz, Iran) were enrolled. IL-10 and IL-17 serum levels were measured at diagnosis, before initiation of treatment (acute stage), 3 months later (subacute stage). These cytokines were also measured in samples obtained from 30 gender- and age-matched healthy subjects, which were considered as control values. RESULTS: Patients' IL-10 and IL-17 levels were higher in both acute and subacute stages as compared to controls. However, no significant differences existed between the acute stage and control groups for both cytokines. Moreover, subacute levels were significantly higher than their acute and control levels. CONCLUSION: This study demonstrated the alteration of IL-10 and IL-17 levels in aseptic non-vasculitic CSVT. The rise in subacute IL-10 can be explained by the assumption that IL-10 is released as an anti-inflammatory response to subside the effects of IL-17 mediated reactions. More importantly, the immediate sampling in the acute stage did not allow enough time for triggering the immune system to produce such mediators. However, a balance was established between IL-10 and IL-17 in the subacute stage to prevent further tissue damage.

Cerebral sinovenous thrombosis in neonatal antiphospholipid syndrome: a new entity?

Neonatal antiphospholipid syndrome (neonatal APS) seems to be exceedingly rare, as the antiphospholipid antibodies (aPL) related thrombosis in the neonatal period. The pathogenesis of perinatal aPL related thrombosis may be explained both by the transplacental passage of the maternal antibodies and by the production of de novo antibodies by the neonate. However, few cases of neonatal APS are reported in the literature, especially regarding arterial thrombotic events. In particular, only two cases of neonatal aPL related isolated cerebral sinovenous thrombosis (CSVT) are described in the literature. Despite its frequency, CSVT results in significant mortality and morbidity, probably also due to the difficulty in early diagnosis and then in correct managing in the neonatal period. A diagnosis of neonatal APS should be considered in the evaluation of neonates with CSVT, as well as in any case of neonatal thrombosis, to correctly manage the affected neonates and counsel the mother for future pregnancies.

Prevention of thrombosis relapse in antiphospholipid syndrome patients refractory to conventional therapy using intravenous immunoglobulin.

OBJECTIVES: To investigate the long-term effects of megadoses of intravenous immunoglobulin (IVIG) in a small cohort of patients with relapsing primary APS resistant to conventional treatments. METHODS: Five primary APS patients, 4 women, mean age 45.1 years (range 31-76 years), were considered eligible for IVIG therapy due to relapsing thrombotic events (4 recurrent venous thromboses, 2 ischaemic cerebral strokes, 2 pulmonary thromboembolisms, 1 thrombotic event on the vena cava filter), despite conventional therapy with anticoagulants. All patients had anti-nuclear antibodies at low-medium titre without other signs or symptoms of systemic lupus erythematosus. IVIG was combined with hydroxychloroquine and, in patients with cerebral strokes, acetylsalicylic acid. Three consecutive daily infusions of IVIG were administered intravenously at a dose of 0.4 g/kg/day every month for 3 months, followed by a single monthly infusion for 9 months. RESULTS: No further thromboses occurred in the 5 treated patients (mean follow-up 89.2 months, range 61-114). Visual analogue score (VAS 0-10) improved (mean 3.5, range 3.0-5.0, before, and 7.35, range 9.9-6.0, p= 0.05) after IVIG treatment. CONCLUSIONS: In a long-term (>5 years) open study in a small cohort of high risk primary APS patients, IVIG was found to be effective in preventing recurrent thrombosis. Full understanding of the mechanisms and efficacy, as well as the optimal doses of IVIG in APS patients with recurrent thrombosis, will require appropriately designed clinical studies. Presently, IVIG use is restricted by costs and limited availability.

Clinical significance of anti-annexin V antibody in acute cerebral ischemia.

BACKGROUND: Antiphospholipid antibodies (aPLs) are associated with vascular occlusive events. Lupus anticoagulant (LA) and anticardiolipin antibody (aCL) are two aPLs commonly used for screening test. However, other aPLs are reported to play a role in the thrombotic events in other disorders, especially autoimmune disease. We investigated the clinical significance of the anti-annexin V antibody (aAV) in patients with acute cerebral ischemia; annexin V promotes anticoagulant activity via inhibition of prothrombin activation. METHODS: A total of 187 patients with acute cerebral infarction or transient ischemic attack, and 66 control subjects were included in this prospective study. IgG type aAV was determined by enzyme-linked immunosorbent sandwich assay in the patient and control groups. The presence of LA and aCL were determined in the patient group using the usual screening method. RESULTS: IgG aAV was detected in 26 of the 187 patients (13.9%), but only in three of the 66 control subjects (4.5%; P=0.043). Among the 26 aAV positive patients, only five patients were positive for LA or aCL. The presence of IgG aAV was significantly associated with acute cerebral ischemia: one stroke event (OR, 4.39; 95% CI, 1.21-16.01), and two or more stroke events (OR, 3.91; 95% CI, 1.09-14.07). CONCLUSION: IgG aAV was detected in a significant percentage of the patients with acute cerebral ischemia compared with the control group. The presence of IgG aAV did not usually coincide with LA or aCL. Thus aAV should be considered as a possible associated factor for acute cerebral ischemia.

Autoantibodies against the fibrinolytic receptor, annexin A2, in cerebral venous thrombosis.

BACKGROUND AND PURPOSE: Cerebral venous thrombosis (CVT) may be a manifestation of underlying autoimmune disease. Antibodies against annexin A2 (anti-A2Ab) coincide with antiphospholipid syndrome, in which antiphospholipid antibodies (aPLA) are associated with thrombosis in any vascular bed. Annexin A2, a profibrinolytic receptor and binding site for ß2-glycoprotein-I, the main target for aPLA, is highly expressed on cerebral endothelium. Here we evaluate the prevalence of anti-A2Ab in CVT. METHODS: Forty individuals with objectively documented CVT (33 women and 7 men) and 145 healthy controls were prospectively studied for hereditary and acquired prothrombotic risk factors, classical aPLA, and anti-A2Ab. RESULTS: One or more prothrombotic risk factors were found in 85% of CVT subjects, (pregnancy/puerperium in 57.5%, classical aPLA in 22.5%, and hereditary procoagulant risk factors in 17.5%). Anti-A2Ab (titer >3 SD) were significantly more prevalent in patients with CVT (12.5%) than in healthy individuals (2.1%, P<0.01, OR, 5.9). CONCLUSIONS: Anti-A2Ab are significantly associated with CVT and may define a subset of individuals with immune-mediated cerebral thrombosis.

Recurrent ischemic stroke in a patient with idiopathic thrombocytopenic purpura.

Recurrent cerebral infarctions developed in a patient with idiopathic thrombocytopenic purpura (ITP). At the time of the first stroke, there were large thrombi in the right proximal internal carotid artery (ICA) and an occlusion of the right terminal ICA. The occlusion was recanalized by intra-arterial infusion of urokinase. After 20 months, he suffered another ischemic attack. The autoantibodies in ITP directed against antigens presented on both platelets and endothelial cells might induce the endothelial damage, thrombus formation, and embolic occlusion of the artery.

[Leucocytes' ability to accumulate and secrete cholesterol is a nonspecific factor of immune inflammation in patients with atherothrombotic stroke].

The aim of the study was investigation of nonspecific inflammation markers in atherosclerotic injury of major arteries of the head (MAH). A complex study, including duplex ultrasonography, CT, measurement of cholesterol and its fractions, has been conducted in 85 patients with atherothrombotic (72 patients) and lacunar (23 patients) stroke. The ability of leucocytes' culture to accumulate and secrete cholesterol in vitro was studied as a nonspecific inflammatory marker of lesion of atherosclerotic MAH. A high level of this index was characteristic of atherothrombotic type of stroke comparing to lacunar stroke and the control group. Furthermore, high levels of this index correlated with severity of atherosclerotic injury of MAH, in particular with plaques. The dynamics of the index after 24-day therapy by statins (vasilip) is presented. We suppose that the protective influence of statins in patients after ischemic stroke may be caused by the effects on the level of immune competent cells including reducing leucocytes ability to accumulate and secrete protein-lipid complexes.

Cerebral thrombotic microangiopathy and antiphospholipid antibodies in Aicardi-Goutieres syndrome--report of two sisters.

Cerebral thrombotic microangiopathy was found at autopsy in one of two sisters with Aicardi-Goutieres syndrome, whereas the other revealed increased serum levels of anticardiolipin IgG antibodies (measured only in the living sister); both typical features of systemic lupus erythematosus. These findings add support to the suggestion that Aicardi-Goutieres syndrome and systemic lupus erythematosus are closely related disorders in which dysregulated production of interferon-alpha might play a crucial role.

High prevalence of anti-prothrombin antibody in patients with deep vein thrombosis.

The present study was designed to determine the prevalence of lupus anticoagulant (LA) antibody and several antibodies for antiphospholipid syndrome (APS) in patients with deep vein thrombosis (DVT)/pulmonary embolism (PE) (n = 48), cerebral thrombosis (CT, n = 30), systemic lupus erythematosus (SLE, n = 22), and idiopathic thrombocytopenic purpura (ITP, n = 30). The presence of antibodies was examined by using the respective ELISA kits. LA was positive in 38.6% of patients with DVT/PE, suggesting that LA is one of the most important risk factors in DVT/PE. The highest prevalence of anti-beta(2) glycoprotein I (beta(2)GPI) IgG was in CT and SLE, followed by DVT, and none in ITP and healthy volunteers (control, n = 40), suggesting that it is related to thrombosis, particularly arterial thrombosis. The highest prevalence of anti-prothrombin (aPT) IgG antibody was in DVT, followed by CT and SLE, and none in ITP and the control, suggesting that it is related to thrombosis, especially venous thrombosis. The highest prevalence of antiphospholipid (aPL) IgG was in DVT, CT, and SLE, but 0% in ITP and control. On the other hand, aPL IgM, anti-annexin V IgG, and anti-annexin V IgM were positive in patients both with and without thrombosis, suggesting that they are not related to thrombosis. Our results indicated that among the anti-phospholipid antibodies, LA is the most sensitive marker for APS while anti-beta(2)GPI IgG, aPT IgG, and aPL IgG are risk factors for thrombosis. In particular, aPT IgG is a significant marker for DVT/PE.

Infant stroke and beta-2-glycoprotein 1 antibodies: six cases.

UNLABELLED: The binding of autoimmune anticardiolipin antibodies to phospholipid has been shown to require a plasma cofactor, beta-2-glycoprotein 1 (beta2-GPI). Antibodies against beta2-GPI are associated with both venous and arterial thrombosis in adults and have been suggested as a new antiphospholipid syndrome marker. We present six children with cerebral thrombosis at the age of 0-12 months, who had IgG antibodies to beta2-GPI (titers 26, 29, 31, 39, 101 and 109 SGU, when 20 SGU was the cut-off). In at least four patients, the conventional antiphospholipid markers (lupus anticoagulant and IgG and IgM anticardiolipin) were negative. All six children had normal results in the other routine thrombophilia assays (thrombin time, antithrombin, protein C, protein S, factor V Leiden mutation, prothrombin mutation). CONCLUSION: the anti-beta-2 glycoprotein 1 assay, requiring only 5 microl serum, may be a useful addition to antiphospholipid-antibody diagnostics in cases of paediatric stroke.

Study of some markers of inflammation in atherothrombotic pathogenesis of acute ischemic stroke.

Recent researches focused on the study of the role of the inflammation in the atherothrombotic pathogenesis of the acute cerebral ischemia. The aim of the study was to identify some acute phase proteins with possible role in the pathogenesis of the ischemic stroke. Some acute phase proteins were prospectively investigated by standard methods in sera of 78 patients with ischemic stroke in the first admission day. There were two groups according to neurological deficit one month after the ischemic stroke: good outcome and poor outcome. In the second group mean value of C-reactive protein (CRP) was 0.122 +/- 0.06 g/l (p < 0.01), mean value of C3 was 2.61 +/- 0.36 g/l (p < 0.01), mean value of C4 was 0.73 +/- 0.07 g/l (p < 0.05), mean value of alpha 1-antitrypsin (AAT) was 4.9 +/- 0.46 g/l (p < 0.01), mean value of alpha 1-antichymotrypsin (ACT) was 0.33 +/- 0.04 g/l (p < 0.01), mean value of alpha 1-acid glycoprotein (AGA) was 1.12 +/- 0.15 g/l, (p < 0.05), mean value of fibrinogen was 2.6 +/- 0.22 g/l (p < 0.01), mean value of haptoglobin was 2.8 +/- 0.33 g/l, (p < 0.05), mean value of transferrin was 2.8 +/- 0.26 g/l (p < 0.05), mean value of ferritin was 238 +/- 22.42 microg/l (p < 0.001), mean value of fibronectin was 2.14 +/- 0.17 g/l (p < 0.05), mean value of ceruloplasmin was 1.23 +/- 0.24 g/l (p < 0.01). High significant values of ferritine and significant values of CRP, C3, AAT, ACT and fibrinogen were observed in patients with poor outcome. The presented data suggest that the studied markers are useful to appreciate the role of the inflammatory reaction in the atherothrombotic pathogenesis of the ischemic stroke.

Neurologic manifestations of the antiphospholipid syndrome.

Neurologic disorders are among the most prominent clinical manifestations associated with the antiphospholipid syndrome. Such neurologic disorders are predominantly related to focal central nervous system thrombo-occlusive events. This review summarizes the latest data regarding the clinical aspects of stroke and other neurologic manifestations associated with antiphospholipid antibodies.

Arterial thrombosis associated with anticardiolipin and anti-beta2-glycoprotein-I antibodies in patients with non-Hodgkin's lymphoma: a report of two cases.

Autoimmune phenomena in lymphoid malignancies are often observed. However, clinical manifestations such as a secondary antiphospholipid syndrome in the presence of antiphospholipid antibodies are rarely reported. Furthermore, in the few cases of lymphomas so far reported with thrombosis associated with elevated antiphospholipid antibodies, the anti-beta2-glycoprotein-I antibodies have not been studied. We report on two cases of arterial thrombosis occuring in patients with B-cell lymphoma who presented with positive anticardiolipin and anti-beta2-glycoprotein-I antibodies. Our observation suggests that patients with non-Hodgkin's lymphoma and both anticardiolipin and anti-beta2-glycoprotein-I antibodies may be, similar to lupus patients, at considerable risk towards thrombosis, especially towards arterial thrombosis.

Role of NMDA receptor signaling in the regulation of inflammatory gene expression after focal brain ischemia.

Inflammatory mediators are involved in the pathogenesis of focal ischemic brain damage. In this study we used quantitative reverse transcriptase-polymerase chain reaction to analyze the spatiotemporal pattern of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and inducible nitric oxide synthase (iNOS) expression in focal ischemia of the rat brain. Focal ischemia of the rat parietal cortex was induced noninvasively by photothrombosis of cortical microvessels. In a proportion of the animals NMDA receptor signaling was blocked by the noncompetitive receptor antagonist MK-801. Within 4 h after ischemia we found induction of TNF-alpha and IL-1beta mRNA not only in the infarcts but also in all representative tissue samples removed from noninfarcted frontal, lateral, and occipital cortex of the ipsilateral, but not contralateral hemisphere. Contrastingly, the expression of iNOS mRNA remained restricted to the evolving infarcts. Pretreatment with MK-801 strongly inhibited remote cytokine expression (mean reduction by 80% relative to vehicle treated animals at 4 h; P<0.001) whereas in the lesions only partial reductions in the expression of IL-1beta and iNOS mRNA were found. Our data for the first time demonstrate remote cytokine induction following focal brain ischemia and suggest that NMDA receptor-mediated signaling can activate inflammatory gene expression independently from the occurrence of neuronal cell death.