Association between three eNOS polymorphisms and intracranial aneurysms risk: a meta-analysis

Endothelial nitric oxide synthase rs1799983 gene polymorphism is associated with the risk of developing intracranial aneurysm

PURPOSE

The intracranial aneurysm (IA) rupture is associated with a subarachnoid hemorrhage. One third of patients die, and one third remain depend for daily activities. Genetic factors are crucial in the formation and clinical evolution of IAs. Multiple loci have been associated with AIs, much of them implicating multiple pathways related to vascular endothelial maintenance and extracellular matrix integrity. Thus, the aim of our study was to characterize whether polymorphisms in genes implicated in the vascular endothelial maintenance could modify the risk of developing IAs.

SUBJECTS AND METHODS

We have studied 176 patients with IA recruited in the Service of Neurosurgery at the University Hospital of Valladolid (Spain) and a control group if 150 sex-matched healthy subjects. Clinical variables were collected from each patient. We have analyzed VEGFA rs833061, VEGFR2 rs2071559, endothelin rs5370, endoglin rs3739817, and eNOS rs1799983 polymorphisms.

RESULTS

Our results showed that allele T of the eNOS rs1799983 polymorphism is correlated with decreased risk of developing the disease; thus, allele G of the eNOS rs1799983 polymorphism increased the risk of developing IA.

CONCLUSION

The association of eNOS rs1799983 polymorphism with the risk to suffer IA reinforces the hypothesis that genetic variants in eNOS gene could be crucial in the pathogenesis of IA.

VEGF and eNOS variants may influence intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IDD) is a common and complex condition. Vascular endothelial growth factor (VEGF) is one of the key regulators of angiogenesis and vascular permeability. Nitric oxide (NO) plays a role in various physiological events. The endothelial nitric oxide synthase (eNOS) that catalyses NO generation are crucial for the regulation of NO level. This study aimed to evaluate the association between VEGF/ eNOS gene variants with IDD.

MATERIALS AND METHODS

Two hundred ninety-one subjects (111 IDD patients and 180 controls) were included in the present case-control study. VEGF -2549 insertion/deletion (I/D) and eNOS VNTR variants were analysed by PCR method. The results of this analysis were evaluated for statistical significance.

RESULTS

There were no statistically significant differences in genotype and allele distribution of VEGF -2549 I/D/ eNOS VNTR variants between IDD patients and control subjects. We then evaluated the association between the allele frequencies of these variants and clinical features of IDD. Lumber IDD was more common in patients carrying VEGF I/D variant D allele (p < 0.001). Also, patients with lumbar disc herniation, cervical disc herniation, lumbar stenosis, and lumbar IDD had more 4 b allele (p = 0.005, p < 0.001, p < 0.001, and p = 0.03, respectively).

CONCLUSIONS

In conclusion, this study demonstrates first time that some clinical characteristics of IDD have been associated with allele frequencies of VEGF -2549 I/D/ eNOS VNTR variants.

Underlying mechanism of hemodynamics and intracranial aneurysm

In modern society, subarachnoid hemorrhage, mostly caused by intracranial aneurysm rupture, is accompanied by high disability and mortality rate, which has become a major threat to human health. Till now, the etiology of intracranial aneurysm has not been entirely clarified. In recent years, more and more studies focus on the relationship between hemodynamics and intracranial aneurysm. Under the physiological condition, the mechanical force produced by the stable blood flow in the blood vessels keeps balance with the structure of the blood vessels. When the blood vessels are stimulated by the continuous abnormal blood flow, the functional structure of the blood vessels changes, which becomes the pathophysiological basis of the inflammation and atherosclerosis of the blood vessels and further promotes the occurrence and development of the intracranial aneurysm. This review will focus on the relationship between hemodynamics and intracranial aneurysms, will discuss the mechanism of occurrence and development of intracranial aneurysms, and will provide a new perspective for the research and treatment of intracranial aneurysms.

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.

Tissue-specific relaxin-2 is differentially associated with the presence/size of an arterial aneurysm and the severity of atherosclerotic disease in humans

Circulating or tissue-related biomarkers are of clinical value for risk stratification in patients with abdominal aortic aneurysms. Relaxin-2 (RL2) has been linked to the presence and size of arterial aneurysms, and to the extent of atherosclerosis in human subjects. Here, we assessed the expression levels of RL2 in aneurysmal (AA, n = 16) and atherosclerotic (ATH, n = 22) arteries, and established the correlation between RL2 levels and the presence/size of AA and the clinical severity of atherosclerosis. The expression levels of metalloproteinases (MMPs) and endothelial nitric oxide synthetase (eNOS) were also detected for correlations with different phenotypes of atherosclerosis and AA. Temporal artery biopsy specimens (n = 6) and abdominal aortic tissues harvested from accident victims during autopsy (n = 10) were used as controls. Quantitative tissue biomarker analysis revealed that tissue-specific RL2 was increased in patients with larger or symptomatic AA compared to subjects with atherosclerotic disease and healthy controls. In situ RL2 levels were proportional to the size and the severity of aneurysmatic disease, and were substantially elevated in patients with symptomatic aneurysm of any diameter or asymptomatic aneurysm of a diameter >350% of that of the normal artery. In contrast, tissue RL2 was inversely associated with the clinical severity of atherosclerotic lesions. Correlation between RL2 and MMP2 was different between ATH1 and ATH2, depending on atherosclerosis grade. Overall, tissue RL2 is differentially associated with discrete phenotypes of arterial disease and might exert multipotent biological effects on vascular wall integrity and remodeling in human subjects.

Endothelial dysfunction in cerebral aneurysms

Endothelial cell (EC) dysfunction is known to contribute to cerebral aneurysm (CA) pathogenesis. Evidence shows that damage or injury to the EC layer is the first event in CA formation. The mechanisms behind EC dysfunction in CA disease are interrelated and include hemodynamic stress, hazardous nitric oxide synthase (NOS) activity, oxidative stress, estrogen imbalance, and endothelial cell-to-cell junction compromise. Abnormal variations in hemodynamic stress incite pathological EC transformation and inflammatory zone formation, ultimately leading to destruction of the vascular wall and aneurysm dilation. Hemodynamic stress activates key molecular pathways that result in the upregulation of chemotactic cytokines and adhesion molecules, leading to inflammatory cell recruitment and infiltration. Concurrently, oxidative stress damages EC-to-EC junction proteins, resulting in interendothelial gap formation. This further promotes leukocyte traffic into the vessel wall and the release of matrix metalloproteinases, which propagates vascular remodeling and breakdown. Abnormal hemodynamic stress and inflammation also trigger adverse changes in NOS activity, altering proper EC mediation of vascular tone and the local inflammatory environment. Additionally, the vasoprotective hormone estrogen modulates gene expression that often suppresses these harmful processes. Crosstalk between these sophisticated pathways contributes to CA initiation, progression, and rupture. This review aims to outline the complex mechanisms of EC dysfunction in CA pathogenesis.

Endothelial nitric oxide synthase gene polymorphisms and erectile dysfunction in chronic pain

OBJECTIVES

To investigate whether endothelial nitric oxide synthase (eNOS) T786C, 4VNTR and G894 T gene polymorphisms could mediate in andrological treatment response in Spaniards.

SUBJECT PATIENTS/METHODS

The study participants were Spaniard males with erectile dysfunction (ED) and chronic pain (n = 105) recruited at the Pain Unit. eNOS polymorphisms were genotyped by quantitative polymerase chain reaction using Taqman specific probes. Statistical analyses were carried out using R-3.2.4 software.

RESULTS

A total of 69 patients required andrological treatment and 76% of them improved ED upon iPED5 (20%), testosterone (35%) or iPDE5/testosterone treatment (45%); being significantly better in T786C-CC patients. Multivariate regression analysis indicated that age, opioid daily dose and carriage of T786C-C allele influenced the risk and ED severity in Spaniard chronic pain patients.

CONCLUSION

T786C polymorphism at eNOS locus appeared to be a major contributor in the variable erectile function iPDE5/testosterone response in Spaniards.

Genetic susceptibility to cerebrovascular disease: A systematic review

Investigation of genetic susceptibility to cerebrovascular disease has been of growing interest. A systematic review of human studies assessing neurogenomic aspects of cerebrovascular disease was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. Any association study exploring genetic variants located in the exome associated with one of the major cerebrovascular diseases with at least 500 subjects was eligible for inclusion. Of 6874 manuscripts identified, 35 studies met the inclusion criteria. Most studies of interest focused on ischemic stroke and cerebrovascular occlusive disease. Large cohort genetic association studies on hemorrhagic cerebrovascular disease were less common. In addition to rare, well-established monogenic conditions with significant risk for cerebrovascular disease, a number of genetic variants are also relevant to cerebrovascular pathogenesis as part of a multifactorial process. The 45 polymorphisms identified were located in genes involved in processes related to endothelial and vascular health (15 (33.4%) variants), plasma lipid metabolism (10 (22.2%) variants), inflammation (9 (20%) variants), coagulation (3 (6.7%) variants), and blood pressure modulation (2 (4.4%) variants), and other (6 (13.3%) variants). This work represents a comprehensive overview of genetic variants in the exome relevant to ischemic and hemorrhagic stroke pathophysiology.

The correlation between gene polymorphisms of endothelial nitric oxide synthase and aneurismal subarachnoid hemorrhage

To discuss the association of the T786C and G894T polymorphisms of endothelial nitric oxide synthase (eNOS) with the occurrence and prognosis of aneurismal subarachnoid hemorrhage (aSAH). One hundred sixty-nine patients with aSAH were collected as the case group, which was divided into the good prognosis group and adverse prognosis group according to the condition 3 months after the treatment. One hundred fifty-six healthy volunteers were collected as the control group. The allele and genotype of T786C and G894T polymorphisms of eNOS were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The genotype and allele frequency of eNOS were compared between different groups. And then, the risk factors of aSAH occurrence and prognosis were analyzed by using the logistic regression model. Both the genotype and allele frequency distributions of T786C and G894T between the case group and control group were significantly different (P < 0.05). There were significant differences in the distribution of G894T and T786C allele frequency and G894T genotype between the good prognosis group and adverse prognosis group, and there was no difference in T786C genotype. The results of the logistic regression analysis indicated that T786C and G894T polymorphisms of eNOS were independent influencing factors on the occurrence of aSAH and the G894T polymorphism was also closely related to the prognosis. T786C and G894T polymorphisms of eNOS gene were correlated with the occurrence and prognosis of aSAH, and the G894T polymorphism might be an independent influencing factor.

Collagen type-I A2 gene polymorphisms and susceptibility to intracranial aneurysms: a meta-analysis of genetic association studies

BACKGROUND

The development, evolution and rupture of intracranial aneurysms are in part related to genetic factors. The role of collagen type-I a2 genetic polymorphisms has not been clarified yet.

MATERIAL AND METHODS

A meta-analysis was realized by means of a genotype model-fitting process (allele contrast, recessive, dominant, additive and co-dominant), and a model-free approach using the generalized odds ratio. The latter was assessed in association to the degree of dominance (h-index).

RESULTS

No statistically significant association was documented between EX28 G>C collagen type-I a2 variant and intracranial aneurysms (generalized odds ratio = 1.23, 95% confidence interval = 0.57, 2.63). Significant associations between INT46 T>G collagen type I a2 variant and intracranial aneurysms were documented in three models, the dominant [0.52 (0.38, 069)], the co-dominant [0.50 (0.32, 0.78)] and the allele contrast models [0.63 (0.49, 0.82)]. The generalized odds ratio was estimated to be as high as 1.94 (1.23, 3.06). The degree of dominance (h-index = -1.54) indicated that the TG genotype was characterized by lower risk of developing intracranial aneurysms compared to the TT genotype.

CONCLUSIONS

The available literature data demonstrated that there is no association of collagen type-(2a) and intracranial aneurysms, through EX28 G>C (rs42524) polymorphism according to the model-fitting process and the model-free approach. Regarding the INT46 T>G (rs2621215) polymorphisms, the latter models indicated that there could be a protective effect of the G-allele against the development of intracranial aneurysms. However, the majority of studies are from East Asia, therefore the results are applicable primarily to that patient population.

Late onset MELAS with m.3243A > G mutation and its association with aneurysm formation

We reported a 53-year-old with late-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) accompanied by aneurysm and large vessel dilations. Most studies have focused on microangiopathy causing stroke-like episodes. We report a case to describe large vessel involvement in clinical considerations, and possible mechanisms of aneurysm formation. We recommended regular angiographic examination for patients with MELAS.

Heterozygous eNOS Deficient Mice as a Model to Examine the Effects of eNOS Haploinsufficiency on the Cerebral Circulation

Nitric oxide derived from endothelial nitric oxide synthase (eNOS) has been shown to be a major mediator of endothelium-dependent responses in cerebral blood vessels. Loss of a single eNOS gene is not associated with any apparent negative consequences on endothelial function in most blood vessels. In contrast, we have recently demonstrated that heterozygous eNOS gene deficiency in combination with a high fat diet is associated with marked impairment of endothelial function. These findings provide an important example of eNOS haploinsufficiency and one that directly impacts the cerebral vasculature. A major mechanism associated with the impairment of endothelial function with eNOS deficiency and a high fat diet appears to be related to increases in plasma IL-6 that serves to further reduce the bioavailability of NO either directly or indirectly via reductions in eNOS expression or activity and via increases in vascular superoxide. Taken together, these findings provide important insights into genetic and molecular mechanisms that promote endothelial dysfunction in response to a high fat diet in cerebral blood vessels with inherent reductions in eNOS gene expression, such as those due to eNOS gene polymorphisms. These findings also highlight the importance of eNOS+/- mice to study the effects of eNOS haploinsufficiency on cerebral blood vessels.

Genetic findings in sport-related concussions: potential for individualized medicine?

Concussion is a traumatic transient disturbance of the brain. In sport, the initial time and severity of concussion is known giving an opportunity for subsequent analysis. Variability in susceptibility and recovery between individual athletes depends, among other parameters, on genetic factors. The genes-encoding polypeptides that determine incidence, severity and prognosis for concussion are the primary candidates for genetic analysis. Genetic polymorphisms in the genes contributing to plasticity and repair (APOE), synaptic connectivity (GRIN2A), calcium influx (CACNA1E), uptake and deposit of glutamate (SLC17A7) are potential biomarkers of concussion incidence and recovery rate. With catalogued genetic variants, prospective genotyping of athletes at the beginning of their career will allow medical professionals to improve concussion management and return-to-play decisions.

Role of Endoglin Insertion and rs1800956 Polymorphisms in Intracranial Aneurysm Susceptibility: A Meta-Analysis

Endoglin is an essential molecule during angiogenesis, vascular development, and integrity. Till now, many studies have investigated the association between endoglin polymorphisms and intracranial aneurysm (IA) risk, with the results remained inconclusive. Therefore, we performed a meta-analysis to summarize the possible association.We searched PubMed and Embase until June 2015 to identify studies addressing the association between endoglin polymorphisms and IA risk. The summary odds ratios (ORs) and their corresponding 95% confidence interval (CI) were calculated to assess the strength of the association.Eleven studies with a total of 1501 cases and 2012 controls were finally included in this meta-analysis, with 10 studies investigating endoglin 6-bp insertion (6bINS) polymorphism and 4 studies investigating 1800956 polymorphism. No significant association between endoglin 6bINS polymorphism and IA risk was detected in overall estimation (I/I vs wt/I + wt/wt: OR = 1.21, 95% CI = 0.87-1.69) or in the subgroup analysis by ethnicity, control source, or ruptured status. However, we observed an association with borderline significance of 6bINS with IA occurrence (I/I vs wt/I + wt/wt: OR = 1.49, 95% CI = 0.99-2.25, P = 0.058) in studies applying matched controls. Furthermore, we detected a significant association for 6bINS polymorphism of endoglin with increased risk of familial IA (I vs wt, OR = 1.64, 95% CI = 1.10-2.42) but not sporadic IA (I vs wt, OR = 1.09, 95% CI = 0.68-1.45). With regard to rs1800956, our pooled results indicated a significantly decreased IA risk in individuals carrying C allele (C/C vs G/C + G/G: OR = 0.65; 95% CI = 0.45-0.94).This meta-analysis provided no evidence for the association between 6bINS polymorphism with overall IA risk. However, we detected a significant association of 6bINS allele with increased risk of familial IA. Also, we found that rs1800956 was significantly related to IA occurrence. Further, well-designed studies with large sample size are warranted and updated meta-analysis is needed to verify our findings.