Current Neurovascular Research - Volume 13, Issue 1, 2016

Acetylcholine (ACh) is the main mediator associated with the anti-inflammatory cholinergic pathway. ACh plays an inhibitory role in several inflammatory conditions. Sepsis is a severe clinical syndrome characterized by bacterial dissemination and overproduction of inflammatory mediators. The aim of the current study was to investigate the participation of endogenous ACh in the modulation of inflammatory response induced by a model of polymicrobial sepsis. Wild type (WT) and vesicular acetylcholine transporter knockdown (VAChTKD) mice were exposed to cecal ligation and perforation- induced sepsis. Levels of Tumor Necrosis Factor Alpha (TNF-α) and bacterial growth in peritoneal cavity and serum, and neutrophil recruitment into peritoneal cavity were assessed. The concentration of TNF-α in both compartments was higher in VAChTKD in comparison with WT mice. VAChTKD mice presented elevated burden of bacteria in peritoneum and blood, and impairment of neutrophil migration to peritoneal cavity. This phenotype was reversed by treatment with nicotine salt. These findings suggest that endogenous ACh plays a major role in the control of sepsis-associated inflammatory response.

Chronic cerebral hypoperfusion (CCH) is a general pathophysiological condition occurring in vascular dementia (VaD) associated with negative impact on cognitive functions. Ryanodine as well as cysteinyl leukotriene-1 receptors (RyRs and CysLT1Rs) are extensively present in the central nervous system, where they participate in regulation of cognition, motivation, inflammation and neurodegeneration. The purpose of this study is to examine the role of ruthenium red; a selective RyR blocker as well as montelukast; a specific CysLT1 antagonist in CCH induced VaD in mice. Two vessel occlusion (2VO) or permanent ligation of bilateral common carotid arteries technique was used to induce CCH in mice. Animals with bilateral carotid arteries occlusion have revealed impaired learning and memory (Morris water maze), cholinergic dysfunction (increased acetylcholinesterase activity) as well as increased brain oxidative stress (reduction in brain superoxide dismutase, glutathione and catalase with an increase in thiobarbituric acid reactive substance level), with increased brain infarct size (2,3,5-triphenylterazolium chloride staining). While, administration of ruthenium red and montelukast considerably attenuated CCH induced cognitive impairments, cholinergic dysfunction, brain oxidative stress as well as brain damage. The results suggest that bilateral carotid arteries occlusion induced CCH has brought out VaD, which was attenuated by treatment with ruthenium red and montelukast. Therefore, modulation of RyRs as well as CysLT1 receptors may provide help in conditions involving CCH such as cognitive impairment and VaD.

Diabetes is associated with deficits in memory and cognitive functions and sustained inflammation. Recently, involvement of NF-ΚB (nuclear factor kappa-light-chain-enhancer of activated B cells) has been postulated in many cognitive functions, immune system and inflammation. Despite of role of NF-ΚB in inflammation, a large gap remains in understanding of the mechanisms and consequences of NF-ΚB activation in the central nervous system.In this study, we have evaluated the effects of NF-ΚB activation inhibitor on memory function, neurotransmitter levels changes and brain inflammatory cytokines in type-2 diabetic rats. BAY 11-7082 (BAY) was used as a pharmacological inhibitor of IΚBα (inhibitor of kappa B alpha) phosphorylation to block NF-ΚB activation. Type-2 diabetic rats showed significant memory impairment at 15th week. Three weeks BAY treatment produced significant increase in Morris water maze test learning and memory performance. Diabetic animals also showed improved performance in passive avoidance and Y-maze test paradigm following treatment with NF-ΚB inhibitor BAY. BAY treatment did not show any significant effect on blood glucose and insulin levels. NF-ΚB inhibition significantly reduced neuroinflammation as evidenced by decrease in IL-6 and TNF-α levels. BAY treatment in diabetic rats also increased the phosphorylation of CREB which indicates that the NF-ΚB activation inhibitor engage a CREB regulated mechanism in-vivo. Moreover, BAY also reversed the alterations in brain glutamate and GABA levels in diabetic rats. These findings corroborate that NF-ΚB inhibition may be an effective treatment strategy in diabetes associated cognitive deficits.

Diabetes mellitus is considered as a main risk factor for vascular dementia. In the past, we have reported the induction of vascular dementia (VaD) by experimental diabetes. This study investigates the efficacy of a nifedipine, a calcium channel blocker and pioglitazone in the pharmacological interdiction of pancreatectomy diabetes (PaD) induced vascular endothelial dysfunction and subsequent VaD in rats. Attentional set shifting (ASST) and Morris water-maze (MWM) test were used for assessment of learning and memory. Vascular endothelial function, blood brain barrier permeability, serum glucose, serum nitrite/nitrate, oxidative stress (viz. aortic superoxide anion, brain thiobarbituric acid reactive species and brain glutathione), brain calcium and inflammation (myeloperoxidase) were also estimated. PaD rats have shown impairment of endothelial function, blood brain barrier permeability, learning and memory along with an increase in brain inflammation, oxidative stress and calcium. Administration of nifedipine and pioglitazone significantly attenuated PaD induced impairment of learning, memory, blood brain barrier permeability, endothelial function and biochemical parameters. It may be concluded that nifedipine, a calcium channel blocker may be considered as a potent pharmacological agent for the management of PaD induced endothelial dysfunction and subsequent VaD.

In patients with severe carotid artery stenosis, the effects of carotid artery reopening, achieved either by carotid endarterectomy (CEA) or carotid artery stenting (CAS), on cognitive functions remain elusive. Herein, we conducted a prospective study to determine whether and to what extent CEA and CAS affected cognitive performance. Patients admitted to the Department of Neurology or Vascular Surgery in Nanjing First Hospital from December 2012 to March 2015 with a diagnosis of severe carotid artery stenosis (>70%) were included in the study. Among them, 77 patients underwent CEA, 81 patients underwent CAS, and 77 patients who refused to receive aforementioned interventions were enrolled in control group. Of note, all patients in this study received basic pharmacological treatment according to the American Heart Association/American Stroke Association guidelines. Cognitive functions were evaluated by a broad spectrum of neuropsychological tests including the Mini-mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA) and event related potential P300 on the day prior to and at 3 months after indicated intervention. When compared with basic pharmacological treatment, both CEA and CAS significantly increased the scores of MMSE and MoCA at 3 months following procedures. Meanwhile, a significant reduction of P300 score was also observed in patients underwent CEA or CAS. In addition, the changes in MMSE, MoCA and P300 scores over time between CEA and CAS groups were not statistically significant. Taken together, our findings suggest an improvement of cognitive functions following carotid artery reopening. Meanwhile, the beneficial effects of CEA and CAS on cognitive performance seem to be equivalent.

Although about 80% of patients with cerebral venous sinus thrombosis have a good prognosis, some patients develop severe complications and a small proportion do not survive. The study included patients who had been diagnosed with cerebral venous sinus thrombosis in our hospital from May 2008 to February 2014. Based on the modified Rankin Scale (mRS) scores at 3 months for outcome, the patients were divided into two groups: good prognosis (mRS score ≤ 2) and poor prognosis (mRS score > 2). Univariate and multivariate regression analysis were performed to identify significant prognostic factors for poor outcome. A total of 86 patients with cerebral venous sinus thrombosis, 54 males and 32 females, average age 41.3 years (range, 3-83 years), were enrolled. Of these 86 patients, 64 (74.4%) had a good prognosis and 22 (25.6%) a poor prognosis. Univariate analysis revealed that dyskinesia was a significant risk factor (factor with odds ratio >1) for poor prognosis. In multivariate analysis, the risk of poor prognosis in patients with dyskinesia was 23 times higher than for those without dyskinesia (p < 0.001). Thrombosis of the sinus transervus was found to reduce the risk of poor prognosis in both univariate and multivariate analysis. Most patients with cerebral venous sinus thrombosis have a good prognosis but patients with dyskinesia have a poorer prognosis.

Cerebral small-vessel disease (SVD) is characterized by periventricular white matter (WM) changes and general brain atrophy. SVD is prevalent in elderly individuals and is frequently associated with the development of vascular dementia (VaD). Studies of the molecular basis of SVD are sparse. We have to gain further insight into the pathogenic mechanisms of SVD. Therefore, we compared gene expression patterns in the brains of SVD and control patients, in order to identify cellular pathways changed in diseased brains. We compared the expression of mRNA transcripts in postmortem, macroscopically normal-appearing human brain tissues isolated from frontal, temporal and occipital cortical and subcortical regions in 5 SVD and 5 non-SVD control patients. Significant expression changes were determined by fold change F>1.2 in either direction, and p<0.05. We identified 228 genes differentially expressed in cortex (89 up-, 139 down-regulated) and 555 genes in WM (223 up-, 332 down-regulated) in SVD patients. Pathway analyses revealed that upregulated genes were associated with inflammation and apoptosis in WM, suggesting active cell death. Downregulated genes were associated with coagulation and fatty and amino acids metabolisms. In the cortex, down-regulated genes were principally associated with neuronal functions. Our data revealed widespread changes in the transcriptome profiles in the cortex and WM of human SVD brains, with a predominance of changes in WM. We provide for the first time a comprehensive view of the molecular alterations in human SVD brains that seem to contribute to the neuropathogenesis of SVD.

Some inflammatory proteins, such as cyclooxygenase (COX)-2 and prostaglandin (PG) E2 are hypothesized to be implicated in the development of moyamoya disease (MMD). However, the functional roles of COX-2/PGE2 in the pathogenesis of MMD remain elusive. In this study, tiny pieces of middle cerebral artery (MCA) and superficial temporal artery (STA) were surgically harvested from 18 adult MMD patients and 5 surgical control patients. The expression levels of COX-2 and microsomal prostaglandin E2 synthase-1 (mPGES-1) in the vascular walls were immunohistochemically detected. With additional 10 healthy controls, the plasma levels of PGE2 were also measured by enzyme-linked immunosorbent assay (ELISA). Obvious intimal thickening was observed in both STA and MCA of MMD patients, but not in the controls. However, the MCA had a thicker intima than the STA (P < 0.01). Although plasma concentrations of PGE2 had no differences among the MMD patients, surgical controls and healthy controls, MCA of most MMD patients (15/18, 83.3%) were stained positively for COX-2 and all patients for mPGES-1. Staining of both COX-2 and mPGES-1 was more abundant in the MCA of hemorrhagic patients than those in their ischemic counterparts (P = 0.001 and 0.029, respectively). The expression levels of COX-2 were positively correlated with those of mPGES-1 (r = 0.647, P = 0.004). Positive COX-2 and mPGES-1 expressions were detected neither in the MCA samples from the surgical controls nor in all STA specimens. Our findings indicate that COX-2/PGE2 may be associated with the MCA occlusion and the hemorrhagic stroke in patients with MMD.

The association between chronic kidney disease and spontaneous hemorrhagic transformation (HT) in patients with acute ischemic stroke is seldom reported. We performed this study to identify whether reduced estimated glomerular filtration rate (eGFR) is associated with spontaneous HT in acute ischemic stroke patients, and examine whether the association depends on stroke etiology. Patients diagnosed with acute ischemic stroke whose serum creatinine levels at admission were available were consecutively and prospectively enrolled in the Chengdu Stroke Registry Database. All were analyzed on admission by cranial computed tomography (CT) scanning, followed by regular magnetic resonance imaging (MRI) 2-3 days later and afterwards CT scan if neurological symptoms deteriorated. HT was defined based on the MRI or later CT, and eGFR was calculated using the Modification of Diet in Renal Disease equation. Univariate analysis and multivariable logistic regression were performed to determine whether reduced eGFR, defined as < 60 ml/min/1.73m2, was associated with spontaneous HT. The association was also assessed in subgroups of patients classified according to the criteria of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Of the 1,645 patients enrolled, 123 (7.5%) developed spontaneous HT and 215 (13.1%) had reduced eGFR. Reduced eGFR was significantly associated with increased risk of spontaneous HT in all ischemic stroke patients (OR 1.821, 95% CI 1.081 to 3.06, P=0.024), and in the subgroup of large artery atherosclerosis, not in the cardio-embolism stroke group (OR 1.588, 95% CI 0.642 to 3.782, P=0.327). Reduced eGFR did not increase the risk of symptomatic hemorrhagic transformation (OR 0.937, 95%CI 0.247 to 3.577, P=0.924). In conclusion, reduced eGFR was significantly associated with increased risk of spontaneous HT in all ischemic stroke patients, and in large artery atherosclerosis, not in cardio-embolism stroke. Reduced eGFR did not increase the risk of symptomatic HT.

Bilateral common carotid artery (CCA) ligation in rabbits is a model for basilar terminus (BT) aneurysm formation. We asked if this model could be replicated in rats. Fourteen female Sprague Dawley rats underwent bilateral CCA ligation (n=8) or sham surgery (n=6). After 7 days, 5 ligated and 3 sham rats were euthanized for histological evaluation of BT aneurysm formation, while the remaining rats were imaged with magnetic resonance angiography, euthanized, and subjected to corrosion casting of the Circle of Willis (CoW). 3D micro computed tomography images of CoW casts were used for flow simulations at the rat BT, and electron micrographs of the casts were analyzed for aneurysmal and morphological changes. Results from these analyses were compared to rabbit model data (n=10 ligated and n=6 sham). Bilateral CCA ligation did not produce aneurysmal damage at the rat BT. While the surgical manipulation increased rat basilar artery flow, fluid dynamics simulations showed that the initial hemodynamic stress at the rat BT was significantly less than in rabbits. Rats also exhibited fewer morphological and pathological changes (minor changes only occurred in the posterior CoW) than rabbits, which had drastic changes throughout the CoW. A comparison of CoW anatomies demonstrated a greater number of branching arteries at the BT, larger CoW arteries in relation to basilar artery, and a steeper BT bifurcation angle in the rat. These differences could account for the lower hemodynamic stress at the BT and in the cerebrovasculature of the rat. In conclusion, bilateral CCA ligation in rats does not recapitulate the rabbit model of early flow-induced BT aneurysm. We suspect that the different CoW morphology of the rat lessens hemodynamic insults, thereby diminishing flow-induced aneurysmal remodeling.