From hypertension to stroke: mechanisms and potential prevention strategies

High Blood Pressure Increases the Risk of Poor Outcome at Discharge and 12-month Follow-up in Patients with Symptomatic Intracranial Large Artery Stenosis and Occlusions: Subgroup analysis of the CICAS Study

Aims

The purpose of this study was to discuss the relationship between blood pressure and prognosis of patients with symptomatic intracranial arterial stenosis.

Methods

Data on 2426 patients with symptomatic intracranial large artery stenosis and occlusion who participated in the Chinese Intracranial Atherosclerosis (CICAS) study were analyzed. According to the JNC 7 criteria, blood pressure of all patients was classified into one of the four subgroups: normal, prehypertension, hypertension stage I, and hypertension stage II. Poor outcomes were defined as death and functional dependency (mRS 3‐5) at discharge or at 1 year.

Results

For patients with intracranial stenosis of 70% to 99%, the rate of poor outcome at discharge was 19.3%, 23.5%, 26.8%, and 39.8% (P = 0.001) for each blood pressure subgroup. For patients with intracranial large artery occlusion, the rates were 17.6%, 22.1%, 29.5%, and 49.8%, respectively (P < 0.0001). The rate of poor outcome at 12‐month follow‐up was 12.6%, 15.3%, 28.5%, and 27.9% (P = 0.0038) in patients with stenosis of 70% to 99% for each blood pressure subgroup and 11.6%, 21.5%, 23.9%, 35.1% (P < 0.0001) in patients with occlusion.

Conclusions

For patients with severe intracranial arterial stenosis or occlusion, higher hypertension stages are associated with an increased risk of poor outcome at discharge and 12‐month follow‐up.

The impact of blood pressure on kidney function in the elderly: a cross-sectional study

BACKGROUND/AIMS

Intensive blood pressure (BP) target decreases blood perfusion of kidneys that attenuates the benefits of BP treatment in elderly hypertensive individuals. The optimal BP goal for renal function in the hypertensive elderly has been unclear. We investigated the impact of BP on renal function to define the appropriate BP target in the elderly.

METHODS

A total of 28,258 elderly subjects were categorized into normotensive (Norm), hypotensive (Hypo) and hypertensive (Hyper) groups according to BP levels. Systolic, diastolic and pulse BP (SBP, DBP and PBP) were further stratified by 10 mmHg. Blood urea nitrogen, serum creatinine, uric acid, glomerular filtration rate (GFR), renal insufficiency prevalence (RIP) and proteinuria prevalence (PP) were compared among different groups and BP strata. The RIP and PP in the elderly with obesity, hyperlipidemia or diabetes in Norm, Hypo and Hyper groups were evaluated.

RESULTS

GFR in Hypo and Hyper groups was significantly lower than that in Norm group. The RIP and PP was higher in Hypo and Hyper groups than that in the Norm group. Proteinuria became more prevalent when SBP was >140 mmHg or <90 mmHg. DBP>80 mmHg increased PP while DBP<70 mmHg increased RIP. PBP>60 mmHg led to an increased RIP and PP. Obesity or hyperlipidemia only combined with hypertension caused a significantly increased RIP and PP. Diabetes independent of hypertension contributed to higher RIP and PP.

CONCLUSIONS

The most beneficial BP target for kidney function in the elderly may be SBP of 90-140 mmHg and DBP of 70-80 mmHg. PBP <60 mmHg may be appropriate.

Vascular aspects of cognitive impairment and dementia

Hypertension and stroke are highly prevalent risk factors for cognitive impairment and dementia. Alzheimer's disease (AD) and vascular dementia (VaD) are the most common forms of dementia, and both conditions are preceded by a stage of cognitive impairment. Stroke is a major risk factor for the development of vascular cognitive impairment (VCI) and VaD; however, stroke may also predispose to AD. Hypertension is a major risk factor for stroke, thus linking hypertension to VCI and VaD, but hypertension is also an important risk factor for AD. Reducing these two major, but modifiable, risk factors-hypertension and stroke-could be a successful strategy for reducing the public health burden of cognitive impairment and dementia. Intake of long-chain omega-3 polyunsaturated fatty acids (LC-n3-FA) and the manipulation of factors involved in the renin-angiotensin system (e.g. angiotensin II or angiotensin-converting enzyme) have been shown to reduce the risk of developing hypertension and stroke, thereby reducing dementia risk. This paper will review the research conducted on the relationship between hypertension, stroke, and dementia and also on the impact of LC-n3-FA or antihypertensive treatments on risk factors for VCI, VaD, and AD.

Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions

BACKGROUND

Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs).

METHODS

To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-type VGNs at different developmental stages using whole-cell patch clamping.

RESULTS

C-type VGNs underwent significant age-dependent transition from single action potential (AP) to repetitive discharge. The coordinate changes between TTX-S and TTX-R Na(+) currents were also confirmed and well simulated by computer modeling. Although 4-AP or iberiotoxin age dependently increased firing frequency, AP duration was prolonged in an opposite fashion, which paralleled well with postnatal changes in 4-AP- and iberiotoxin-sensitive K(+) current activity, whereas less developmental changes were verified in A-types.

CONCLUSION

These data demonstrate for the first time that the neuroexcitability of C-type VGNs increases significantly compared with A-types within initial postnatal weeks evidenced by AP discharge profiles and coordinate ion channel changes, which explain, at least in part, that initial postnatal weeks may be crucial for ontogenesis in visceral afferent reflex function.

Elevated Plasma Factor VIII in Patients with Ischemic Stroke: Does it have any Association with Hypertensive Heart Disease?

BACKGROUND

Elevated factor VIII (FVIII) has been linked with higher risk of vascular events. We aimed to determine the relationship between FVIII and hypertension in patients with acute ischemic stroke.

METHODS

FVIII levels and transthoracic echocardiogram reports were reviewed in patients with acute ischemic stroke who presented to our stroke center between July 2008 and September 2011. Presenting systolic and diastolic blood pressure, history of hypertention, left ventricular hypertrophy, diastolic dysfunction, and depressed left ventricular function (ejection fraction <50%) were compared in patients with normal and elevated FVIII levels.

RESULTS

No differences in presenting blood pressure or frequency of hypertension history were found based on FVIII level. Patients with elevated FVIII had demonstrated a statistically significant higher frequency of diastolic dysfunction (64.8 vs. 43.6%, p=0.042) and a trend towards higher frequency of left ventricular hypertrophy (18.5 vs 5.1%, p=0.073). Median FVIII was significantly higher in patients with left ventricular hypertrophy (194.4 vs 152.9%, p=0.042) and diastolic dysfunction (180.5 vs 149.3%, p=0.031) than patients without these findings.

CONCLUSIONS

Among patients with acute ischemic stroke, FVIII levels were higher when there was evidence of hypertensive heart disease. Synthesis of FVIII may be augmented by the ongoing presence of shear stress and could contribute to the higher risk of vaso-occlusive events in patients with elevated FVIII.

ACE2-Ang-(1-7)-Mas Axis in Brain: A Potential Target for Prevention and Treatment of Ischemic Stroke

The renin-angiotensin system (RAS) in brain is a crucial regulator for physiological homeostasis and diseases of cerebrovascular system, such as ischemic stroke. Overactivation of brain Angiotensin-converting enzyme (ACE) - Angiotensin II (Ang II) - Angiotensin II type 1 receptor (AT1R) axis was found to be involved in the progress of hypertension, atherosclerosis and thrombogenesis, which increased the susceptibility to ischemic stroke. Besides, brain Ang II levels have been revealed to be increased in ischemic tissues after stroke, and contribute to neural damage through elevating oxidative stress levels and inducing inflammatory response in the ischemic hemisphere via AT1R. In recent years, new components of RAS have been discovered, including ACE2, Angiotensin-(1-7) [Ang-(1-7)] and Mas, which constitute ACE2-Ang-(1-7)-Mas axis. ACE2 converts Ang II to Ang-(1-7), and Ang-(1-7) binds with its receptor Mas, exerting benefical effects in cerebrovascular disease. Through interacting with nitric oxide and bradykinin, Ang-(1-7) could attenuate the development of hypertension and the pathologic progress of atherosclerosis. Besides, its antithrombotic activity also prevents thrombogenic events, which may contribute to reduce the risk of ischemic stroke. In addition, after ischemia insult, ACE2-Ang-(1-7)-Mas has been shown to reduce the cerebral infarct size and improve neurological deficits through its antioxidative and anti-inflammatory effects. Taken together, activation of the ACE2-Ang-(1-7)-Mas axis may become a novel therapeutic target in prevention and treatment of ischemia stroke, which deserves further investigations.

Involvement of acetylcholine-α7nAChR in the protective effects of arterial baroreflex against ischemic stroke

AIMS

Decreased baroreflex sensitivity is associated with poor outcome in many cardiovascular diseases including stroke, but the molecular mechanism underlying this relationship is unclear. This work was designed to test the hypothesis that acetylcholine (ACh) and α7 nicotinic ACh receptor (α7nAChR) mediate the protection of arterial baroreflex against stroke.

METHODS

Sinoaortic denervation (SAD) was used to impair the function of arterial baroreflex, and anticholinesterase agents were used to activate the cholinergic system and increase endogenous ACh. Middle cerebral artery occlusion (MCAO) was performed in the α7nAChR knockout (KO) mice and Sprague-Dawley rats.

RESULTS

We found decreased expression of vesicular ACh transporter (VAChT) and α7nAChR in rat brain after SAD. In rats subjected to MCAO, neostigmine significantly reduced the infarct size. The protective effects of neostigmine were abolished by selective nAChR antagonist vecuronium but not by mAChR antagonist anisodamine. In addition, the effect of neostigmine disappeared in α7nAChR KO mice. In cultured neurons, ACh inhibited cell death induced by H(2) O(2) . In cultured microglial cells, ACh decreased the release of proinflammatory cytokines induced by lipopolysaccharide. These in vitro effects were blocked by selective α7nAChR antagonists.

CONCLUSION

Taken together, these findings indicate that the ACh-α7nAChR involved in the protective effects of arterial baroreflex against ischemic stroke.

Effects of combination therapy with levamlodipine and bisoprolol on stroke in rats

AIM

To examine the effects of combination with levamlodipine and bisoprolol on stroke in rats.

METHODS

For acute study, Systolic blood pressure (SBP) and heart period (HP) were monitored in conscious stroke prone-spontaneously hypertensive rats (SHR-SP) and sinoaortic denervation (SAD) rats before and after intragastric administration of either drug at a single dose. Rats were subjected to middle cerebral arterial occlusion (MCAO) half an hour after drug administration; sacrificed 24 h later to measure the infarct size. For long-term study, drugs (either alone or in combination) were delivered via food to SHR-SP. The survival time was recorded.

RESULTS

SBP was significantly reduced by combination therapy both in SHR-SP and SAD rats. Neutralization on heart rate (HR) was observed in combination. The drug combination increased baroreflex sensitivity (BRS) and reduced SBP variability (SBPV). In chronic experiments, the lifespan of SHR-SP rats exposed to the drug combination was longer than that in rats exposed to either drug alone. The infarct area was the smallest in subjects receiving drug combination in SD rats both with and without SAD.

CONCLUSION

Combined use of levamlodipine and bisoprolol produced better protection against stroke.

The power combination of blood-pressure parameters to predict the incidence of plaque formation in carotid arteries in elderly

Hypertension is considered as one of the major risk factors of atherosclerosis, especially for carotid artery plaque, which is a sign for cardiovascular incapacity and cerebral infarction. As adult age, systolic blood pressure (SBP or S) tends to rise and diastolic blood pressure (DBP or D) tends to fall, thus the pulse pressure (PP) will increase. The vascular injury was directly proportional to the level of SBP, and inversely proportional to DBP. But so far, studies of the vascular injury based on SBP and DBP measurement were mostly qualitative. The exact contribution of each parameter to the vascular injury has not been quantitatively identified. In this study, we employed a mathematical model to predict the risk for plaques of carotid arteries in aged people and combined the SBP, DBP and heart rate (HR) to perform a quantitative analysis. We analyzed 1672 males who were over 60-year-old and hospitalized due to atherosclerosis-related diseases and received a 24-h arterial blood pressure monitoring (ABPM) examination. These patients were divided into 19 subgroups using the ABPM data, 24-h average SBP, DBP and HR as variables based on the ascending order of the magnitude of each element. We developed a new index, namely the dynamic level (DL) which correlated best with the plaque formation of carotid arteries among all the well-established indexes for blood pressure. We demonstrated that index DL has better correlation to plaques incidence tendency (p < 0.0001) when compared to either SBP (P < 0.05) or PP (P < 0.001) alone. The risk on incidence of the plaques of carotid arteries has positive correlation with first power of SBP and -0.8 power of DBP. This model can be used clinically to predict the occurrence of plaque formation.

Involvement of arterial baroreflex in the protective effect of dietary restriction against stroke

Dietary restriction (DR) protects against neuronal dysfunction and degeneration, and reduces the risk of ischemic stroke. This study examined the role of silent information regulator T1 (SIRT1) and arterial baroreflex in the beneficial effects of DR against stroke, using two distinct stroke models: stroke-prone spontaneously hypertensive rats (SP-SHRs) and Sprague-Dawley (SD) rats with middle cerebral artery occlusion (MCAO). Sirt1 knockout (KO) mice were used to examine the involvement of sirt1. Sinoaortic denervation was used to inactivate arterial baroreflex. Dietary restriction was defined as 40% reduction of dietary intake. Briefly, DR prolonged the life span of SP-SHRs and reduced the infarct size induced by MCAO. Dietary restriction also improved the function arterial baroreflex, decreased the release of proinflammatory cytokines, and reduced end-organ damage. The beneficial effect of DR on stroke was markedly attenuated by blunting arterial baroreflex. Lastly, the infarct area in sirt1 KO mice was significantly larger than in the wild-type mice. However, the beneficial effect of DR against ischemic injury was still apparent in sirt1 KO mice. Accordingly, arterial baroreflex, but not sirt1, is important in the protective effect of DR against stroke.

Telemetric ambulatory arterial stiffness index, a predictor of cardio-cerebro-vascular mortality, is associated with aortic stiffness-determining factors

BACKGROUND

Ambulatory arterial stiffness index (AASI) has been proposed as a new measure of arterial stiffness for predicting cardio-cerebro-vascular morbidity and mortality. However, there has been no research on the direct relationships between AASI and arterial stiffness-determining factors.

METHODS

We utilized beat-to-beat intra-aortic blood pressure (BP) telemetry to characterize AASI in Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). By determination of aortic structural components and analysis of their correlations with AASI, we provided the first direct evidence for the associations between AASI and arterial stiffness-determining factors including the collagen content and collagen/elastin.

RESULTS

Ambulatory arterial stiffness index was positively correlated with pulse pressure in both WKY and SHR, less dependent on BP and BP variability than pulse pressure, and relatively stable, especially the number of BP readings not less than ~36. The correlations between AASI and aortic components were comparable for various AASI values derived from BP readings not less than ~36. Not only AASI but also BP variability and pulse pressure demonstrated a direct relationship with arterial stiffness.

CONCLUSIONS

These findings indicate AASI may become a routine measure in human arterial stiffness assessment. It is recommended to use a cluster of parameters such as AASI, BP variability, and pulse pressure for evaluating arterial stiffness.

Prehypertension is associated with increased carotid atherosclerotic plaque in the community population of Southern China

Background

The proceeding of blood pressure (BP) from normal level to the hypertension has been found to be associated with increased cardiovascular events and multiple vascular risk factors. However, whether the process is associated with increased carotid atherosclerotic plaque per se or not is still unclear.

Methods

Nine hundred and forty-two participants aged from 46 to 75 were enrolled from community population in Southern China. Their metabolic risk factors, carotid intima-media thickness (cIMT) and atherosclerotic plaque formation were analyzed and stratified by different blood pressure levels according to JNC-7 or ESH/ESC-2007 classification.

Results

From low BP level to higher BP level, multiple metabolic risk factors increased linearly. Prehypertension in JNC-7 classification (or normal BP and high normal BP in ESH/ESC-2007 classification) was correlated with thicker cIMT and more plaque formation than normotension (or optimal BP) (p < 0.001). After adjusting multiple metabolic factors, the differences were still significant (p < 0.05). Furthermore, prehypertensive participants had a trend to be thicker carotid IMT (OR and its 95% CI: 1.65, 0.97-2.82, p = 0.067) and significantly higher carotid plaque occurrence (OR and its 95% CI: 2.36, 1.43-3.88, p = 0.001) than normotensive ones. However, there was no significant difference of cIMT and plaque formation between normal BP and high normal BP (p > 0.05). Plaque formation in prehypertension was as significant as that in hypertension.

Conclusion

Prehypertension is associated with significantly increased carotid atherosclerotic plaque and is a primary stratify risk factor for carotid atherosclerosis which could cause ischemic stroke in middle-aged and elderly population in Southern China.

Clinical characteristics, management, and functional outcomes in Chinese patients within the first year after intracerebral hemorrhage: analysis from China National Stroke Registry

AIMS

The aim of this study was to understand the association between clinical characteristics, medical management, and functional outcomes in Chinese patients with nontraumatic intracerebral hemorrhage (ICH).

METHODS

The China National Stroke Registry (CNSR) was a prospective cohort study that included 132 Chinese hospitals. Logistic regression was used to determine the risk factors associated with poor outcomes at 3, 6, and 12 months, post-ICH onset.

RESULTS

Three thousand two hundred fifty five ICH patients with follow-up information up to 1 year post-ICH were included in this study. 49.1%, 47.1%, and 46.0% of ICH patients had poor outcomes at 3, 6, and 12 months, respectively. Age, admission systolic blood pressure, admission Glasgow Coma Score, hematoma volume, withdrawal of support, and complication of gastrointestinal hemorrhage were associated with poor outcomes at 3 and 12 months. Stroke unit care was associated with good outcome at 3 months. Intensive care unit (ICU)/Neurology ICU care was associated with poor outcome at 3 months.

CONCLUSION

This is the first report of long-term functional outcomes in ICH patients from mainland China. Our study elucidates the risk factors that may influence functional outcomes post-ICH and therefore facilitate the development of management strategies to improve ICH care in China.

Risperidone enhances the vulnerability to stroke in hypertensive rats

BACKGROUND

Stroke is the second most common cause of death and a major cause of disability worldwide. Risperidone is an atypical antipsychotic drug that may increase the risk of stroke. The present work examined whether risperidone enhances the vulnerability to stroke in hypertensive rats and the potential mechanisms underlying such action.

METHODS

Experiment 1: Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHRs) and stroke-prone SHRs (SHR-SPs) were treated with risperidone (0.8 and 2.4 mg/kg/d) or vehicle for 30 consecutive days. Tissue damage in response to middle cerebral artery occlusion (MCAO) was measured microscopically. The activity of superoxide dismutase, glutathione peroxidase, the levels of malondialdehyde were also determined. Experiment 2: Survival data were recorded in SHR-SPs that received daily risperidone perpetually. Experiment 3: Effect of risperidone on interleukin-6 and tumor necrosis factor-α was examined in quiescent or LPS-activated cortical microglias from WKY rats. Experiment 4: Potential damage of risperidone exposure to neurons was examined in primary neuronal culture obtained from WKY rats, SHRs, and SHR-SPs.

RESULTS

Risperidone increased infarct areas upon MCAO in SHR-SPs and SHRs, but not in WKY rats. Survival time in SHR-SPs was shortened by risperidone. Apoptosis was augmented by risperidone through enhanced Bax. Risperidone also increased endothelial injury.

CONCLUSIONS

Risperidone enhances the vulnerability to stroke in hypertensive rats through increasing neuronal apoptosis and endothelial injury.

Chronic exposure to nicotine enhances insulin sensitivity through α7 nicotinic acetylcholine receptor-STAT3 pathway

This study was to investigate the effect of nicotine on insulin sensitivity and explore the underlying mechanisms. Treatment of Sprague-Dawley rats with nicotine (3 mg/kg/day) for 6 weeks reduced 43% body weight gain and 65% blood insulin level, but had no effect on blood glucose level. Both insulin tolerance test and glucose tolerance test demonstrated that nicotine treatment enhanced insulin sensitivity. Pretreatment of rats with hexamethonium (20 mg/kg/day) to antagonize peripheral nicotinic receptors except for α7 nicotinic acetylcholine receptor (α7-nAChR) had no effect on the insulin sensitizing effect of nicotine. However, the insulin sensitizing effect but not the bodyweight reducing effect of nicotine was abrogated in α7-nAChR knockout mice. Further, chronic treatment with PNU-282987 (0.53 mg/kg/day), a selective α7-nAChR agonist, significantly enhanced insulin sensitivity without apparently modifying bodyweight not only in normal mice but also in AMP-activated kinase-α2 knockout mice, an animal model of insulin resistance with no sign of inflammation. Moreover, PNU-282987 treatment enhanced phosphorylation of signal transducer and activator of transcription 3 (STAT3) in skeletal muscle, adipose tissue and liver in normal mice. PNU-282987 treatment also increased glucose uptake by 25% in C2C12 myotubes and this effect was total abrogated by STAT3 inhibitor, S3I-201. All together, these findings demonstrated that nicotine enhanced insulin sensitivity in animals with or without insulin resistance, at least in part via stimulating α7-nAChR-STAT3 pathway independent of inflammation. Our results contribute not only to the understanding of the pharmacological effects of nicotine, but also to the identifying of new therapeutic targets against insulin resistance.

Synergic effects of levamlodipine and bisoprolol on blood pressure reduction and organ protection in spontaneously hypertensive rats

AIMS

Stroke is a major cause of disability and death worldwide. Hypertension is one of the most important risk factors for stroke. The objective of this work was to study the synergic effects of levamlodipine and bisoprolol on blood pressure reduction and organ protection in spontaneously hypertensive rats (SHR).

METHODS

Blood pressure was continuously monitored in conscious SHR. For acute study, a single dose of drugs was administrated via an intragastric catheter. For chronic study (4 months), drugs were delivered via rat chow.

RESULTS

A single dose of levamlodipine (from 1 mg/kg), bisoprolol (from 0.125 mg/kg), and their combinations significantly decreased blood pressure. The levamlodipine-induced tachycardia and the bisoprolol-induced bradycardia were temporized by the combination of these two drugs. Upon chronic treatment, this combination also decreased blood pressure variability and reduced organ damage.

CONCLUSION

Levamlodipine and bisoprolol produce synergic effects on blood pressure reduction and organ protection in SHR.

E-selectin deficiency attenuates brain ischemia in mice

AIMS

To determine whether E-selectin deficiency can attenuate brain ischemia in a mouse model of focal cerebral ischemia.

METHODS

E-selectin was determined in spontaneously hypertensive rats (SHRs) and stroke-prone spontaneously hypertensive rats (SHR-SPs). E-selectin knockout (Es(-/-) ) mice and wild-type control (WT) mice underwent permanent distal middle cerebral artery occlusion (MCAO). Behavioral analyses were performed followed by the measurement of infarct areas. Myeloperoxidase (MPO) protein was determined by Western blot. IL-6, IL-1β, and TNF-α were detected by ELISA. In situ detection of apoptotic cells was performed by TUNEL staining.

RESULTS

The brain and serum E-selectin levels were higher in SHR-SPs than in SHRs (P < 0.05) after salt intake. E-selectin deficiency improved neurological function and reduced infarct area in cerebral ischemic mice. MPO and IL-1β were lower in Es(-/-) mice than in WT mice. In addition, the number of apoptotic cells in Es(-/-) mice was significantly less than in WT mice after MCAO.

CONCLUSIONS

E-selectin deficiency presents protective effect on cerebral ischemia. This protective effect is likely achieved by the inhibition of inflammation and apoptosis.

Tight junction in blood-brain barrier: an overview of structure, regulation, and regulator substances

Blood-brain barrier (BBB) is a dynamic interference that regulates the nutrition and toxic substance in and out of the central nervous system (CNS), and plays a crucial role in maintaining a stable circumstance of the CNS. Tight junctions among adjacent cells form the basic structure of BBB to limiting paracellular permeability. In the present review, the constituents of tight junction proteins are depicted in detail, together with the regulation of tight junction under stimulation and in pathological conditions. Tight junction modulators are also discussed.

Heterozygote genotypes at rs2222823 and rs2811712 SNP loci are associated with cerebral small vessel disease in Han Chinese population

AIMS

With developments of etiology of cerebral small vessel disease (CSVD) and genome-wide association study (GWAS) of stroke, the genetic studies of CSVD are focused on genes related to blood-brain barrier (BBB) and aging. The project aims to investigate the association between CSVD and susceptibility loci and candidate genes.

METHODS

All study subjects admitted Beijing Tiantan Hospital from June 2009 to September 2010 including 197 cerebral small vessel disease patients(S), 198 large artery atherosclerosis control individuals (vascular stenotic rate ≥50% diameter reduction) (L), 200 hypertensive intracerebral hemorrhage control individuals (H) and 197 stroke-free control individuals (C). 15 SNPs in 4 genes (MYLK, AQP4, NINJ2, and INK4/ARF) were genotyped using Multiplex Snapshot assay. Each SNP was first examined between the groups S and C in different genetic models (codominant, dominant, recessive, overdominant, and log-additive). Permutation correction was used to adjust for multiple testing. The significant SNP loci were further analyzed in comparing S with L and H, respectively. Subgroup analysis was also performed for each risk-factor category.

RESULTS

Among the 15 SNPs, rs2222823 and rs2811712 were found to be significantly associated with CSVD after multiple-testing adjustment. The heterozygote (A/T) of rs2222823 of MYLK has an odds ratio of 0.52 (95% CI =[0.35, 0.79], P= 0.002, adjusted P= 0.031) when compared with homozygotes. The heterozygote (C/T) of rs2811712 of INK4/ARF has an odds ratio of 1.75 (95% CI =[1.13-2.71], P= 0.004, adjusted P= 0.050). The SNP rs2222823 was significant (P= 0.035) in comparing S with H. In comparing S versus L, it is significant for the subgroups of patients without diabetes (P= 0.012) and drinking (P= 0.018). rs2811712 was significant in comparing S with L for the subgroups of patients with hyperlipidemia (P= 0.029) and drinking (P= 0.04).

CONCLUSION

The heterozygotes (T/A) at the rs2222823 SNP locus of MYLK gene decreases the risk of having cerebral small vessel disease, while the heterozygotes (C/T) at the rs2811712 SNP locus of INK4/ARF gene increases the risk, suggesting that the MYLK and INK4/ARF are the associated genes of cerebral small vessel disease in Han Chinese population.