Riccardo Di Sciacca

Inflammatory Cytokines in Acute Ischemic Stroke

Three major cytokines, namely, tumor necrosis factor (TNF-alpha), interleukin (IL)-1, and IL-6 are produced by cultured brain cells after various stimuli such as ischemia. Neurones, astrocytes, microglia and oligodendrocytes can produce inflammatory mediators, and cytokine receptors are expressed constitutionally throughout the Central Nervous System (CNS), albeit at low levels. Cytokines are involved in virtually every facet of stroke and they have numerous pro-inflammatory and pro-coagulant effects on endothelium. TNF-alpha expression after stroke stimulates expression of tissue factor and adhesion molecules for leukocytes, release of interleukin-1 (IL-1), nitric oxide, factor VIII/von Willebrand factor, platelet-activating factor and endothelin, suppression of the thrombomodulin-protein C-protein S system, reduction of tissue-plasminogen activator and release of plasminogen activator inhibitor-1. Research into the actions of IL-1beta in the brain initially focused on its role in host defence responses to systemic disease. IL-1beta can also elicit an array of responses which could either inhibit, exacerbate or induce neuronal damage and death. IL-6 can be induced by a variety of molecules including IL-1, TNF-alpha, transforming growth factor-beta and prostaglandins (PGs), and many other mediators such as b-amyloid, interferon-g (IFNg) and IL-4 can potentiate these primary inducers, highlighting the complex nature of IL-6 modulation. Several studies reported that plasma levels of TNF-alpha and IL-6 are associated with prognosis after ischemic stroke and our group showed that plasma levels of cytokines such as TNF-alpha, IL-1beta are different in every diagnostic subtype of ischemic stroke, and how plasma levels of some immunoinflammatory markers and thrombotic-phybrinolitic markers are predictive of acute ischemic stroke diagnosis in the acute setting.

Neuron Protection as a Therapeutic Target in Acute Ischemic Stroke

Involvement of various neurotransmitters and neuromodulators have been shown to contribute to the ischemic injury and neuronal death associated with stroke Role of excitatory amino acid receptor activation, calcium overload, nitric oxide, and oxidative stress in the pathogenesis of ischemic brain damage is well established. Several new strategies are currently emerging, based on recent advances in our understanding of molecular pathways that could be considered as potential therapeutic targets. For example reactive oxygen species (ROS) are important contributors to the secondary injury cascade following traumatic brain injury (TBI), and ROS inhibition has consistently been shown to be neuroprotective following experimental TBI and brain ischemia. Furthermore, more recently, some authors concluded that nonanticoagulant 3K3A-APC exhibits greater neuroprotective efficacy with no risk for bleeding compared with drotrecogin-alfa activated, a hyperanticoagulant form of APC. Excessive calcium entry into depolarized neurons contributes significantly to cerebral tissue damage after ischemia. Included in the sequence of events leading to neuronal death in ischemic tissue following stroke is an excessive and toxic rise in the intracellular Ca(2+)-concentration, predominantly due to an influx of Ca2+ through nonselective cation-channels as well as Ca(2+)-channels.. Some authros conducted a study to investigate whether the enhancement of GABA receptor activity could inhibit NMDA receptor-mediated nitric oxide (NO) production by neuronal NO synthase (nNOS) in brain ischemic injury. The results showed that both the GABA(A) receptor agonist muscimol and the GABA(B) receptor agonist baclofen had neuroprotective effect, and the combination of two agonists could significantly protect neurons against death induced by ischemia/reperfusion. On this basis we conclude that neuroprotection for ischemic stroke refers to strategies, applied singly or in combination, that antagonize the injurious biochemical and molecular events that eventuate in irreversible ischemic injury. There has been a recent explosion of interest in this field, with over 1000 experimental papers and over 400 clinical articles appearing within the past 6 years. These studies, in turn, are the outgrowth of three decades of investigative work to define the multiple mechanisms and mediators of ischemic brain injury, which constitute potential targets of neuroprotection.

Inflammation as a therapeutic target in acute ischemic stroke treatment.

Animal models of focal ischaemia induced by middle cerebral artery occlusion (MCAO) provide most evidence for cellular inflammatory responses in stroke. Permanent MCAO results in a modest neutrophil infiltration at 24 h after ischaemia, predominantly around arterial vessels at the margins of infarction, whereas MCAO with subsequent reperfusion is associated with substantial infiltration by neutrophils throughout the entire infarct. Several studies show that C-reactive protein (CRP), an inflammatory marker, is associated with stroke outcomes and future vascular events. Several drugs, especially hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), have been demonstrated to reduce hsCRP levels independently of their effects on plasma cholesterol. Various cytokines were shown to be expressed in the injured brain. Recent investigations demonstrated that mRNAs of above cytokines were induced in the ischemic rat brain. TNF-alpha is a pleiotropic cytokine that mediates key roles in many physiological and pathological cellular processes including acute and chronic inflammation, programmed cell death or apoptosis, anti-tumor responses, and infection. Pharmaceutical industry to search a small molecule TNF inhibitor have taken multiple strategies. Significant protection after in vivo oral use of SB-239063 from brain injury and neurological deficits was observed in one study. In the same study significant protection from brain injury and neurological deficits was also demonstrated due to i.v post-stroke treatment with the same compound. Leukocyte-endothelial adhesion process consists of several steps, beginning with rolling of the leukocyte on the endothelial surface until it has slowed down to such a degree that it sticks to the endothelium. Treatment with a murine anti-ICAM-1 antibody (enlimomab) has been investigated in patients with acute ischemic stroke in the Enlimomab Acute Stroke Trial (EAST). Unfortunately, the case fatality rate in this trial was significantly higher in the enlimomab patient group than in the placebo group. Furthermore, experimental data have shown that focal cerebral ischemia induces a time-dependent activation of granulocytes, lymphocytes, and macrophages. Dissipation of ATP by CD39 reduced P2X7 receptor stimulation and thereby suppressed baseline leukocyte alphaMbeta2-integrin expression. As alphaMbeta2-integrin blockade reversed the postischemic, inflammatory phenotype of Cd39-/- mice, these data suggest that phosphohydrolytic activity on the leukocyte surface suppresses cell-cell interactions that would otherwise promote thrombosis or inflammation.

Immuno-inflammatory activation in acute cardio-embolic strokes in comparison with other subtypes of ischaemic stroke.

Few studies have examined the relationship between inflammatory biomarker blood levels, cardioembolic stroke subtype and neurological deficit. So the aim of our study is to evaluate plasma levels of immuno-inflammatory variables in patients with cardio-embolic acute ischaemic stroke compared to other diagnostic subtypes and to evaluate the relationship between immuno-inflammatory variables, acute neurological deficit and brain infarct volume. One hundred twenty patients with acute ischaemic stroke and 123 controls without a diagnosis of acute ischaemic stroke were evaluated. The type of acute ischaemic stroke was classified according to the TOAST classification. We evaluated plasma levels of IL-1beta, TNF-alpha, IL-6 and IL-10, E-selectin, P-selectin, sICAM-1,sVCAM-1, vWF, TPA and PAI-1. Patients with ischaemic stroke classified as cardio-embolic (CEI) showed, compared to other subtypes, significantly higher median plasma levels of TNF-alpha , IL-6 and IL-1beta. Furthermore stroke patients classified as lacunar showed, compared to other subtypes, significantly lower median plasma levels of TNF-alpha, IL-6 and IL-1beta. Multiple linear regression showed a significant association between the Scandinavian Stroke Scale (SSS) score at admission and diagnostic subtype, infarct volume of cardio-embolic strokes and some inflammatory variables. Our findings confirm that cardio-embolic strokes have a worse clinical presentation and produce larger and more disabling strokes than other ischaemic stroke subtypes reporting a possible explanation of higher immuno-inflammatory activation of the acute phase.

Arterial stiffness indexes in acute ischemic stroke: Relationship with stroke subtype

INTRODUCTION No study has evaluated both arterial stiffness indexes (PWV and Aix) in patients with an acute cerebrovascular event. The aim of our study was to evaluate arterial stiffness indexes in subjects with acute ischemic stroke and to evaluate the relationship between these indexes and other clinical and laboratory variables. MATERIALS AND METHODS We enrolled all consecutive patients with a diagnosis of acute ischemic stroke admitted to the Internal Medicine Department at the University of Palermo between November 2006 and January 2009, and hospitalized control patients without a diagnosis of acute ischemic stroke. The type of acute ischemic stroke was classified according to the TOAST classification. Carotid-femoral pulse wave velocity (PWV) was evaluated by Applanation tonometry (SphygmoCor) and the aortic pressure waveform was used to calculate the Augmentation index (Aix). RESULTS We enrolled 107 patients with acute ischemic stroke and 102 control subjects matched for age, sex, cardiovascular risk factors and previous cardiovascular morbidity. Stroke patients, compared to subjects without acute ischemic stroke, showed a higher mean Aix (103+/-3.5 mmHg vs. 99+/-4.6 mmHg) and PWV (11.8+/-3.3 m/s vs. 10.02+/-2.29 m/s). Augmentation Index and PWV values in lacunar subjects were significantly higher compared to values observed in LAAS, CEI and subtypes. DISCUSSION Our study shows that patients with acute ischemic stroke show higher arterial stiffness index values. Among stroke patients, lacunar subtype has the highest arterial stiffness indexes. This finding underlines previous data regarding the strict association between hypertension and diabetes and arterial stiffness, owing the higher percentage of hypertensive and diabetic subjects in the lacunar group.

Plasma levels of inflammatory and thrombotic/fibrinolytic markers in acute ischemic strokes: Relationship with TOAST subtype, outcome and infarct site

BACKGROUND The aim of our study was to evaluate in patients with acute ischemic stroke the relationship between immuno-inflammatory variables, clinical outcome and infarct site. MATERIALS AND METHODS We evaluated plasma levels of IL-1beta, TNF-alpha, IL-6 and IL-10, E-selectin, P-selectin, sICAM-1 ,sVCAM-1 vWF, TPA and PAI-1. RESULTS Patients with cardioembolic subtype showed significantly higher median plasma levels of TNF-alpha, IL-6, IL-1beta whereas the lacunar subtype showed significantly lower median plasma levels of TNF-alpha, IL-6 and IL-1beta. CONCLUSIONS A significant association was noted between the severity of neurological deficit at admission, the diagnostic subtype and some inflammatory variables.

Immuno-inflammatory predictors of stroke at follow-up in patients with chronic non-valvular atrial fibrillation (NVAF).

The aim of the present study was to determine the rates of stroke in patients with chronic NVAF (non-valvular atrial fibrillation), evaluating the relationship between plasma levels of inflammatory variables at admission and the occurrence of stroke during a 3-year follow-up. A total of 373 consecutive patients with chronic NVAF were enrolled. Blood samples were drawn within 72 h of admission, and we evaluated plasma levels of IL (interleukin)-1beta, TNF-alpha (tumour necrosis factor-alpha), IL-6, IL-10, E-selectin, P-selectin, ICAM-1 (intercellular adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1) and vWF (von Willebrand Factor). Subsequent patient events (stroke at follow-up) were monitored over a 3 year period. By multivariate analysis, only age, hypertension and high levels of IL-6, TNF-alpha and vWF remained significant predictors of a higher risk of experiencing ischaemic stroke at follow-up. Moreover, plasma values of TNF-alpha, IL-6 and vWF had a significant area under the ROC (receiver operating characteristic) curve. In conclusion, baseline plasma levels of TNF-alpha, IL-6 and vWF are predictors of new-onset ischaemic stroke at follow-up in patients with chronic NVAF.

Arterial stiffness and ischemic stroke in subjects with and without metabolic syndrome

We conducted a study to evaluate arterial stiffness markers in subjects with acute ischemic stroke and metabolic syndrome and in relation to TOAST subtype of stroke. We enrolled 130 patients with acute ischemic stroke and metabolic syndrome, 127 patients with acute ischemic stroke without metabolic syndrome and 120 control subjects without acute stroke. Applanation tonometry to record pulse wave velocity (PWV). Stroke patients with metabolic syndrome, compared control subjects without stroke showed higher PWV. In subjects with ischemic stroke and metabolic syndrome, PWV was more significantly and positively correlated with body mass index, systolic blood pressure, hypertension, diabetes, glucose blood levels, LDL cholesterol levels, total cholesterol levels, micro-albuminuria, carotid plaque, previous brain infarct at neuro-imaging. Our findings underline important role of both small vessel disease and atherosclerosis on arterial stiffness pathogenesis in the clinical setting of metabolic syndrome.

Immune-inflammatory markers and arterial stiffness indexes in subjects with acute ischemic stroke with and without metabolic syndrome

ObjectiveThe aim of our study was to evaluate the associations between arterial stiffness indexes and immune-inflammatory markers in subjects with acute ischemic stroke with and without metabolic syndrome.Materials/MethodsWe enrolled 130 patients with acute ischemic stroke and metabolic syndrome, 127 patients with acute ischemic stroke without metabolic syndrome and 120 control subjects without acute stroke. Applanation tonometry was used to record the augmentation index (Aix) and pulse wave velocity (PWV). We also evaluated plasma levels of C-reactive protein (CRP), Interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), Interleukin-6 (IL-6) and Interleukin-10 (IL-10), E-selectin, P-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), von Willebrand Factor (vWF) plasma levels, tissue plasminogen activator (TPA) and plasminogen activator inhibitor-1 (PAI-1).ResultsIn subjects with acute ischemic stroke and metabolic syndrome we observed higher median plasma values of immuno-inflammatory markers. In acute ischemic stroke patients and metabolic syndrome in relation of each TOAST subtype we observed a more significant positive correlation between PWV and immuno-inflammatory markers.ConclusionsStroke subjects with acute ischemic stroke and metabolic syndrome showed a higher degree of immuno-inflammatory and arterial stiffness indexes possibly due to metabolic background of these types of patients that trigger a more intense immune-inflammatory activation irrespective of stroke subtype, whereas being related to stroke subtype in subjects without metabolic syndrome.

Immuno-inflammatory and thrombotic/fibrinolytic variables associated with acute ischemic stroke diagnosis.

INTRODUCTION Accumulating evidence suggests that inflammation plays an important role in the development of acute cerebrovascular disease. The aim of this study is to evaluate the predictive value of a series of candidate serum immuno-inflammatory and thrombotic/fibrinolitic molecules towards diagnosis of acute ischemic stroke. MATERIALS AND METHODS We enrolled 120 consecutive patients with a diagnosis of acute ischemic stroke and 123 consecutive hospitalized control patients without a diagnosis of acute ischemic stroke. We evaluated plasma levels of IL-1beta, TNF-beta, IL-6 and IL-10, E-selectin, P-selectin, sICAM-1 and sVCAM-1 as markers of immuno-inflammatory activation, vWF plasma levels as a marker of endothelial dysfunction, TPA antigen and PAI-1 plasma levels as a marker of a prothrombotic state. RESULTS TNF-alpha, PAI-1 and TPA on bivariate logistic regression were highly correlated to stroke diagnosis. Among the other variables maintained in the final model ILbeta, Selectin E, were significantly associated with acute ischemic stroke diagnosis, whereas IL-6, VICAM-1, ICAM-1 and neutrophil percentage showed only a slight or no association with stroke diagnosis. Furthermore, only the continuous values of TNF-alpha, PAI-1 and TPA showed a significant predictive value and likelihood ratio, with an area under the ROC curve of 98.6%, 97.1% and 99.9%, respectively. DISCUSSION Our findings could suggest the high diagnostic power of these immuno-inflammatory and thrombotic/fibrinolytic variables in patients with acute ischemic stroke. Although our results are encouraging, additional studies are needed to establish the validity of this approach.