Cardiovascular comorbidities, inflammation, and cerebral small vessel disease.

Cerebral small vessel disease (cSVD) is the most common cause of vascular cognitive impairment and affects all levels of the brain's vasculature. Features include diverse structural and functional changes affecting small arteries and capillaries that lead to a decline in cerebral perfusion. Due to an ageing population, incidence of cSVD is continually rising. Despite its prevalence and its ability to cause multiple debilitating illnesses, such as stroke and dementia, there are currently no therapeutic strategies for the treatment of cSVD. In the healthy brain, interactions between neuronal, vascular, and inflammatory cells are required for normal functioning. When these interactions are disturbed, chronic pathological inflammation can ensue. The interplay between cSVD and inflammation has attracted much recent interest, and this review discusses chronic cardiovascular diseases, particularly hypertension, and explores how the associated inflammation may impact on the structure and function of the small arteries of the brain in cSVD. Molecular approaches in animal studies are linked to clinical outcomes in patients, and novel hypotheses regarding inflammation and cSVD are proposed that will hopefully stimulate further discussion and study in this important area.

Cerebrovascular Anomalies: Perspectives From Immunology and Cerebrospinal Fluid Flow.

Appropriate vascular function is essential for the maintenance of central nervous system homeostasis and is achieved through virtue of the blood-brain barrier; a specialized structure consisting of endothelial, mural, and astrocytic interactions. While appropriate blood-brain barrier function is typically achieved, the central nervous system vasculature is not infallible and cerebrovascular anomalies, a collective terminology for diverse vascular lesions, are present in meningeal and cerebral vasculature supplying and draining the brain. These conditions, including aneurysmal formation and rupture, arteriovenous malformations, dural arteriovenous fistulas, and cerebral cavernous malformations, and their associated neurological sequelae, are typically managed with neurosurgical or pharmacological approaches. However, increasing evidence implicates interacting roles for inflammatory responses and disrupted central nervous system fluid flow with respect to vascular perturbations. Here, we discuss cerebrovascular anomalies from an immunologic angle and fluid flow perspective. We describe immune contributions, both common and distinct, to the formation and progression of diverse cerebrovascular anomalies. Next, we summarize how cerebrovascular anomalies precipitate diverse neurological sequelae, including seizures, hydrocephalus, and cognitive effects and possible contributions through the recently identified lymphatic and glymphatic systems. Finally, we speculate on and provide testable hypotheses for novel nonsurgical therapeutic approaches for alleviating neurological impairments arising from cerebrovascular anomalies, with a particular emphasis on the normalization of fluid flow and alleviation of inflammation through manipulations of the lymphatic and glymphatic central nervous system clearance pathways.

Endothelial Immune Activation by Medin: Potential Role in Cerebrovascular Disease and Reversal by Monosialoganglioside-Containing Nanoliposomes.

Background The function of medin, one of the most common human amyloid proteins that accumulates in the vasculature with aging, remains unknown. We aim to probe medin's role in cerebrovascular disease by comparing cerebral arterial medin content between cognitively normal and vascular dementia (VaD) patients and studying its effects on endothelial cell (EC) immune activation and neuroinflammation. We also tested whether monosialoganglioside-containing nanoliposomes could reverse medin's adverse effects. Methods and Results Cerebral artery medin and astrocyte activation were measured and compared between VaD and cognitively normal elderly brain donors. ECs were exposed to physiologic dose of medin (5 µmol/L), and viability and immune activation (interleukin-8, interleukin-6, intercellular adhesion molecule-1, and plasminogen activator inhibitor-1) were measured without or with monosialoganglioside-containing nanoliposomes (300 µg/mL). Astrocytes were exposed to vehicle, medin, medin-treated ECs, or their conditioned media, and interleukin-8 production was compared. Cerebral collateral arterial and parenchymal arteriole medin, white matter lesion scores, and astrocyte activation were higher in VaD versus cognitively normal donors. Medin induced EC immune activation (increased interleukin-8, interleukin-6, intercellular adhesion molecule-1, and plasminogen activator inhibitor-1) and reduced EC viability, which were reversed by monosialoganglioside-containing nanoliposomes. Interleukin-8 production was augmented when astrocytes were exposed to medin-treated ECs or their conditioned media. Conclusions Cerebral arterial medin is higher in VaD compared with cognitively normal patients. Medin induces EC immune activation that modulates astrocyte activation, and its effects are reversed by monosialoganglioside-containing nanoliposomes. Medin is a candidate novel risk factor for aging-related cerebrovascular disease and VaD.

The anatomy and immunology of vasculature in the central nervous system.

Barriers between circulation and the central nervous system (CNS) play a key role in the development and modulation of CNS immune responses. Structural variations in the vasculature traversing different anatomical regions within the CNS strongly influence where and how CNS immune responses first develop. Here, we provide an overview of cerebrovascular anatomy, focusing on the blood-CNS interface and how anatomical variations influence steady-state immunology in the compartment. We then discuss how CNS vasculature is affected by and influences the development of different pathophysiological states, such as CNS autoimmune disease, cerebrovascular injury, cerebral ischemia, and infection.

Brain Large Artery Lymphocytic Inflammation and Human Immunodeficiency Virus-Related Brain Arterial Remodeling.

The pathogenesis of increased stroke risk in human immunodeficiency virus (HIV) remains unclear. Our study investigated the relationship between adventitial and intimal CD3+ T cells and brain arterial remodeling that potentially contributes to HIV-related vasculopathy and stroke. Large brain arteries from 84 HIV+ cases and 78 HIV- cases were analyzed to determine interadventitial and luminal diameters, intimal and wall thickness, percent stenosis, and the presence of atherosclerosis. Immunohistochemical analysis was performed to detect and visually score CD3, a pan-T-cell marker, in the intima and adventitia. Our study showed that numbers of adventitial CD3+ T cells are lower among persons with HIV than among those without HIV, especially if CD4 counts are <200, though intimal CD3+ T cell numbers did not differ by HIV status. Among those with HIV but CD4 counts of <200 at the time of death, intimal CD3+ T cells were associated with hypertrophic outward remodeling, while among those with HIV and CD4 of >200 or HIV- controls, intimal CD3+ T cells were associated with hypertrophic inward remodeling. We conclude that intimal lymphocytic inflammation is involved in brain arterial remodeling that may contribute to HIV-related cerebrovascular pathology.IMPORTANCE Although mortality from human immunodeficiency virus (HIV) has decreased with the use of combination antiretroviral therapies, there is now an increased risk of cardiovascular and cerebrovascular disease associated with HIV. Thus, there is a need to understand the pathogenesis of stroke in HIV infection. Our study examines how lymphocytic inflammation in brain arteries may contribute to increased cerebral vasculopathy. With this understanding, our study can potentially help direct future therapies to target and prevent brain arterial remodeling processes associated with HIV.

Vasculitis in the Central Nervous System.

Central nervous system (CNS) vasculitides are a heterogeneous group of disorders characterized by an inflammatory cell infiltration and necrosis of blood vessel walls in the brain, spinal cord, and the meninges. The CNS complications are likely to be fatal without judicious use of immunosuppression; thus, early diagnosis may prevent from damage and disability. This chapter updates our knowledge on CNS vasculitis-related immunological mechanisms, neurological complications, diagnosis, and management.

Response of the cerebral vasculature following traumatic brain injury.

The critical role of the vasculature and its repair in neurological disease states is beginning to emerge particularly for stroke, dementia, epilepsy, Parkinson's disease, tumors and others. However, little attention has been focused on how the cerebral vasculature responds following traumatic brain injury (TBI). TBI often results in significant injury to the vasculature in the brain with subsequent cerebral hypoperfusion, ischemia, hypoxia, hemorrhage, blood-brain barrier disruption and edema. The sequalae that follow TBI result in neurological dysfunction across a host of physiological and psychological domains. Given the importance of restoring vascular function after injury, emerging research has focused on understanding the vascular response after TBI and the key cellular and molecular components of vascular repair. A more complete understanding of vascular repair mechanisms are needed and could lead to development of new vasculogenic therapies, not only for TBI but potentially vascular-related brain injuries. In this review, we delineate the vascular effects of TBI, its temporal response to injury and putative biomarkers for arterial and venous repair in TBI. We highlight several molecular pathways that may play a significant role in vascular repair after brain injury.

Proteomic identification of differentially expressed proteins in vascular wall of patients with ruptured intracranial aneurysms.

OBJECTIVE: Intracranial aneurysms (IA) are serious cerebral vascular abnormalities, however, little is known about the mechanisms underlying IA formation, progression and rupture. Therefore, this study aimed to assess protein expression specific to the vascular tissues of IA patients. METHODS: IA samples were intraoperatively collected from 14 patients after microneurosurgical clipping and pooled. Matched superficial temporal artery (STA) tissues collected from the same patients were used as controls. Differentially expressed proteins were identified using isobaric tags for relative and absolute quantification (iTRAQ) and two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS), validated by immunoblot. RESULTS: 816 proteins were found to be differently expressed in IA and healthy tissues. The expression level of 162 proteins differed by at least two fold. Expression of 80 proteins was up-regulated and expression of 82 was down-regulated. According to PANTHER, these proteins were involved in immune responses, cell adhesion, cellular component organization and developmental processes. Azurocidin-1 (AZU1, a known antimicrobial) and Transmembrane 9 superfamily member 1 (TM9SF1, a novel autophagy-related protein) were 8.0 and 8.6 fold up-regulated, respectively, in IA, while Sorbin and SH3 domain-containing protein 2 (SORBS2), involved in signaling complex assembly, was 12.1 fold down-regulated. CONCLUSION: These findings suggest that IA formation and rupture might be related to autophagy and immune responses, which possibly accounts for proteolytic degradation of vessel wall connective tissues and cytoskeleton components.

Varicella zoster virus vasculopathy: clinical features and pathogenesis.

Varicella zoster virus (VZV) vasculopathy is caused by productive virus infection of cerebral arteries, leading to inflammation, pathological vascular remodeling, and ischemic or hemorrhagic stroke. VZV vasculopathy occurs in immunocompetent and immunocompromised individuals and involves both large and small vessels. MRI abnormalities include more deep-seated than superficial lesions, particularly at gray-white matter junctions, and lesions may enhance. Diagnosis is challenging, since stroke can occur months after zoster rash and in the absence of rash or CSF pleocytosis. The best virological test for diagnosis is detection of anti-VZV IgG antibody in the CSF. Pathological studies of VZV-infected arteries from patients with VZV vasculopathy reveal that the arterial adventitia is the initial site of infection, after which virus spreads transmuraly towards the lumen. Histological and immunohistochemical studies of VZV-infected arteries show a thickened intima, disrupted internal elastic lamina, and loss of smooth muscle cells, that likely contribute to weakening of the vessel wall and occlusion. Early in disease, VZV-infected arteries contain CD4+ and CD8+ T cells, macrophages, and rare B cells, in addition to abundant neutrophils in early disease. Importantly, perivascular inflammatory cells underlie the areas of thickened intima, raising the possibility that soluble factors secreted by these cells contribute to arterial remodeling. This review discusses the clinical features of VZV vasculopathy and potential mechanisms of VZV-induced cerebrovascular remodeling and stroke.

Immune complex formation impairs the elimination of solutes from the brain: implications for immunotherapy in Alzheimer's disease.

BACKGROUND: Basement membranes in the walls of cerebral capillaries and arteries form a major lymphatic drainage pathway for fluid and solutes from the brain. Amyloid-ß (Aß) draining from the brain is deposited in such perivascular pathways as cerebral amyloid angiopathy (CAA) in Alzheimer's disease (AD). CAA increases in severity when Aß is removed from the brain parenchyma by immunotherapy for AD. In this study we investigated the consequences of immune complexes in artery walls upon drainage of solutes similar to soluble Aß. We tested the hypothesis that, following active immunization with ovalbumin, immune complexes form within the walls of cerebral arteries and impair the perivascular drainage of solutes from the brain. Mice were immunized against ovalbumin and then challenged by intracerebral microinjection of ovalbumin. Perivascular drainage of solutes was quantified following intracerebral microinjection of soluble fluorescent 3kDa dextran into the brain at different time intervals after intracerebral challenge with ovalbumin. RESULTS: Ovalbumin, IgG and complement C3 co-localized in basement membranes of artery walls 24 hrs after challenge with antigen; this was associated with significantly reduced drainage of dextran in immunized mice. CONCLUSIONS: Perivascular drainage along artery walls returned to normal by 7 days. These results indicate that immune complexes form in association with basement membranes of cerebral arteries and interfere transiently with perivascular drainage of solutes from the brain. Immune complexes formed during immunotherapy for AD may similarly impair perivascular drainage of soluble Aß and increase severity of CAA.

[Vascular factors in the pathogenesis of Alzheimer's disease]. / Vaskuläre Faktoren in der Pathogenese der Alzheimer-Krankheit.

According to the amyloid hypothesis of Alzheimer's disease (AD), the amyloid ß (Aß) peptide, as the primary neurotoxic species, plays a key role in the pathogenesis of the disease. However, many lines of recent evidence also point towards a major importance of early cerebrovascular dysfunction at least for the most common form of the disease, sporadic AD. In the preclinical course not only neuronal but also vascular damage frequently occurs. Cerebral hypoperfusion, blood-brain barrier dysfunction and vascular oxidative stress are typical features of this stage of the disease. Most importantly, such alterations precede the classical pathological hallmarks, such as parenchymal deposition of extracellular amyloid and intracellular neurofibrillary tangles. In this article recent epidemiological, clinical pathological and experimental evidence for an integrative vascular neuronal pathogenetic model of sporadic AD is reviewed.

Evidence that acetylsalicylic acid attenuates inflammation in the walls of human cerebral aneurysms: preliminary results.

BACKGROUND: Inflammatory cells and molecules may play a critical role in formation and rupture of cerebral aneurysms. Recently, an epidemiologic study reported that acetylsalicylic acid (ASA) decreases the risk of aneurysm rupture. The goal of this study was to determine the effects of ASA on inflammatory cells and molecules in the walls of human cerebral aneurysms, using radiographic and histological techniques. METHODS AND RESULTS: Eleven prospectively enrolled patients harboring unruptured intracranial aneurysms were randomized into an ASA-treated (81 mg daily) group (n=6) and an untreated (control) group (n=5). Aneurysms were imaged at baseline using ferumoxytol-enhanced MRI to estimate uptake by macrophages. After 3 months, patients were reimaged before undergoing microsurgical clipping. Aneurysm tissues were collected for immunostaining with monoclonal antibodies for cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), microsomal prostaglandin E2 synthase-1 (mPGES-1), and macrophages. A decrease in signal intensity on ferumoxytol-enhanced MRI was observed after 3 months of ASA treatment. Expression of COX-2 (but not COX-1), mPGES-1, and macrophages was lower in the ASA group than in the control group. CONCLUSIONS: This study provides preliminary radiographical and histological evidence that ASA may attenuate the inflammatory process in the walls of human cerebral aneurysms. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01710072.

Aportación del Doppler de la arteria cerebral media y del genotipado RHD fetal en el manejo de la isoinmunización / Contribution of middle cerebral artery Doppler and fetal RHD genotype in the management of alloimmunization

Objetivo. Evaluar la aplicación clínica de los métodos no invasivos en el manejo de la isoinmunización, durante el período de 2006-2010. Sujetos y métodos. Se estudiaron 70 gestaciones con riesgo de anemia fetal en las que se realizó el estudio Doppler de la velocidad sistólica de la arteria cerebral media (VS-ACM). Se comparó la eficacia de la VS-ACM después de una, 2 o 3 transfusiones intrauterinas. El genotipado fetal RHD en sangre materna se realizó en las gestaciones seguidas en nuestro centro. Resultados. Se practicó cordocentesis en 22 de gestaciones y en 20 se practicó transfusión intrauterina. Las tasas de detección y de falsos positivos de la VS-ACM en la predicción de anemia fetal moderada o severa fueron del 89 y el 15% en gestaciones sin transfusión previa, del 100 y el 41% en los casos con una transfusión previa y del 40 y el 24% cuando se practicaron más de una transfusión. Conclusiones. La VS-ACM mantiene una sensibilidad alta en una transfusión previa aunque su especificidad disminuye (AU)

Objective. To assess the clinical application of non-invasive methods in the management of alloimmunization from 2006 to 2010. Subjects and methods. Seventy pregnancies with risk of fetal anemia were studied by fetal middle cerebral artery peak systolic velocity (MCA-PSV). The efficacy of MCA-PSV was compared between the first, second and third transfusions. Prenatal testing of fetal RHD blood group using maternal blood was performed in pregnancies followed-up in our center. Results. Fetal blood sampling was performed in 22 pregnancies; of these, fetal transfusion was carried out in 20. Detection rates and the false-positive rate of MCA-PSV in the prediction of severe or moderate fetal anemia were 89% and 15% in pregnancies with no previous transfusions, 100% and 41% in patients with one previous transfusion, and 40% and 24% when more than one transfusion was performed. Conclusion. MCA-PSV has high sensitivity when there is one previous fetal transfusion but its specificity is lower (AU)

Isoform-specific immunolocalization of 14-3-3 proteins in atherosclerotic lesions of human carotid and main cerebral arteries.

14-3-3 proteins are now recognized to have a wide range of potential functions and pathological relevance, such as regulating the intercellular signal processes of differentiation, the development and growth of cells, or preventing or mediating cell apoptosis and survival by controlling the localization of potential signaling molecules. We investigated the immunolocalization of 14-3-3 proteins in atherosclerotic lesions of human cerebral and carotid arteries using 14-3-3 isoform-specific antibodies to distinguish 7 isoforms, and confirmed the cell type localization using double immunofluorolabeling. 14-3-3 common (COM)-like immunoreactivity (IR) was intense, mainly in the foam cells and multinucleated giant cells of the carotid artery. The beta, gamma, epsilon, tau, eta, and zeta (6/7) isoform-specific antibodies showed similar results to those with anti-14-3-3 COM antibody. However, among these isoform-specific antibodies, the anti-eta isoform antibody most intensely immunolabeled multinucleated giant cells and foam cells, and the anti-zeta isoform antibody most intensely immunolabeled infiltrating vascular smooth muscle cells (VSMCs), in carotid plaques. Zeta IR was also observed in one part of the mural thrombus and in the nuclei of foam cells. Gamma isoform-like IR was relatively limited in cell components, but extracellular lesions were partly positive for this isoform. In the main cerebral arteries, the anti-epsilon isoform antibody most intensely immunolabeled infiltrating VSMCs in the intima of thickened fibrous cap plaques. Endothelial cells were also positive for the epsilon isoform. These findings may provide a basis for understanding the isoform-specific role associated with atherosclerotic lesions of the cerebral and carotid arteries.

Differential effects of low-dose endotoxin on the cerebral circulation during pregnancy.

It is well-known that the pregnant state is associated with increased sensitivity to endotoxin in renal and uterine circulations; however, the effects on the cerebral circulation are not known. Intravenous infusion of low-dose lipopolysaccharide ([LPS]; 1.5 µg/kg) to pregnant Wistar rats on day 15 of pregnancy caused significantly decreased myogenic tone of posterior cerebral arteries on day 20, which was not seen in similarly treated nonpregnant rats. Pregnancy alone was associated with a 2-to 4-fold increase in inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) messenger RNA (mRNA) in cerebral arteries compared to nonpregnant, suggesting that the cerebral circulation is in a state of inflammation during pregnancy. After LPS treatment, cerebral arteries from pregnant animals had increased iNOS and TNF-α compared to LPS-treated nonpregnant animals, but decreased interleukin 10 (IL-10) and IFN-γ. These results demonstrate that pregnancy enhances sensitivity to the effects of LPS in the cerebral circulation, which may be due to an enhanced inflammatory state during pregnancy.

Brain immunohistopathological study in a patient with anti-NMDAR encephalitis.

BACKGROUND AND PURPOSE: Anti-N-methyl-D-asparate (NMDA) receptor encephalitis is thought to be antibody-mediated. To perform an immunohistopathological study of the inflammatory reaction in a brain biopsy performed before immunomodulatory treatments in a patient with anti-NMDA receptor encephalitis. METHODS: An immunohistochemical study was performed using CD3, CD68, CD20, CD138 and CD1a antibodies. RESULTS: Prominent B-cell cuffing was present around brain vessels accompanied by some plasma cells, while macrophages and T cells were scattered throughout the brain parenchyma. CONCLUSION: These findings suggest that the B cells interact with the T cells and are involved in antibody secretion by the plasma cells.

Lack of complement inhibitors in the outer intracranial artery aneurysm wall associates with complement terminal pathway activation.

Inflammation and activation of the complement system predispose to intracranial artery aneurysm (IA) rupture. Because disturbances in complement regulation may lead to increased susceptibility to complement activation and inflammation, we looked for evidence for dysregulation of the complement system in 26 unruptured and 26 ruptured IAs resected intraoperatively. Immunohistochemical and immunofluorescence results of parallel IA sections showed that deposition of the complement activation end-product C5b-9 was lacking from the luminal part of the IA wall that contained complement inhibitors factor H, C4b binding protein, and protectin as well as glycosaminoglycans. In contrast, the outer, less cellular part of the IA wall lacked protectin and had enabled full complement activation and C5b-9 formation. Decay accelerating factor and membrane cofactor protein had less evident roles in complement regulation. The Factor H Y402H variant, studied in 97 IA patients, was seen as often in aneurysm patients with or without aneurysm rupture as in the control population. The regulatory capacity of the complement system thus appears disturbed in the outer part of the IA wall, allowing full proinflammatory complement activation to occur before aneurysm rupture. Insufficient complement control might be due to matrix remodeling and cell loss by mechanical hemodynamics and/or inflammatory stress. Apparently, disturbed complement regulation leads to an increased susceptibility to complement activation, inflammation, and tissue damage in the IA wall.

Bone marrow-derived progenitor cells in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited disease due to cerebral microangiopathy presenting with variable pictures, including stroke, progressive cognitive impairment, and disability. Mechanisms leading from vessel structural changes to parenchymal damage and eventually to clinical expression are not fully understood. Among pathogenic processes, endothelial dysfunction has been hypothesized. Endothelial progenitor cells and circulating progenitor cells (CPCs) derived from bone marrow participate in endothelium structure and function maintenance and contribute to ischemic area revascularization. No data are available about these cells in CADASIL. Our objective in this study was to evaluate endothelial progenitor cells and CPCs role in CADASIL. METHODS: Twenty-nine patients with CADASIL and 29 sex- and age-matched control subjects were enrolled. Cells were measured in peripheral blood using flow cytometry. Endothelial progenitor cells were defined as positive for CD34/KDR, CD133/KDR, and CD34/CD133/KDR; and CPCs as positive for CD34, CD133, and CD34/CD133. RESULTS: Endothelial progenitor cells were significantly lower in patients with CADASIL than in control subjects (CD34/KDR: 0.05 versus 0.1 cells/microL, P=0.005; CD133/KDR: 0.07 versus 0.1 cells/microL, P=0.006; CD34/CD133/KDR: 0.05 versus 0.1 cells/microL, P=0.001). The difference remained significant after adjusting for age, sex, and statin use. CPCs were not significantly lower in CADASIL, but patients with stroke or dementia had significantly reduced CPC levels than patients without (CD34: 1.68 versus 2.95 cells/microL, P=0.007; CD133: 1.40 versus 2.82 cells/microL, P=0.004; CD34/CD133: 1.44 versus 2.75 cells/microL, P=0.004). CPC levels significantly correlated with cognitive and motor performance measures. CONCLUSIONS: We have documented an association between endothelial progenitor cells and CPCs and CADASIL, extending previous data about the presence of endothelial dysfunction in this disease and its potential role in modulating phenotype.