Genetic variants of connexin37 are associated with carotid intima-medial thickness and future onset of ischemic stroke

Genetic Polymorphisms of Ischemic Stroke in Asians

The increasing incidence of ischemic stroke emphasizes the necessity for early detection and preventive strategies. Diagnostic biomarkers currently available for ischemic stroke only become detectable shortly before the manifestation of stroke symptoms. Genetic variants associated with ischemic stroke offer a potential solution to address this diagnostic limitation. However, it is crucial to acknowledge that genetic variants cannot be modified in the same way as epigenetic changes. Nevertheless, individuals carrying risk or protective variants can modify their lifestyle to potentially influence the associated epigenetic factors. This study aims to summarize specific variants relevant to Asian populations that may aid in the early detection of ischemic stroke and explore their impact on the disease's pathophysiology. These variants give us important information about the genes that play a role in ischemic stroke by affecting things like atherosclerosis pathway, blood coagulation pathway, homocysteine metabolism, transporter function, transcription, and the activity of neurons regulation. It is important to recognize the variations in genetic variants among different ethnicities and avoid generalizing the pathogenesis of ischemic stroke.

Somatic GJA4 gain-of-function mutation in orbital cavernous venous malformations

Orbital cavernous venous malformation (OCVM) is a sporadic vascular anomaly of uncertain etiology characterized by abnormally dilated vascular channels. Here, we identify a somatic missense mutation, c.121G > T (p.Gly41Cys) in GJA4, which encodes a transmembrane protein that is a component of gap junctions and hemichannels in the vascular system, in OCVM tissues from 25/26 (96.2%) individuals with OCVM. GJA4 expression was detected in OCVM tissue including endothelial cells and the stroma, through immunohistochemistry. Within OCVM tissue, the mutation allele frequency was higher in endothelial cell-enriched fractions obtained using magnetic-activated cell sorting. Whole-cell voltage clamp analysis in Xenopus oocytes revealed that GJA4 c.121G > T (p.Gly41Cys) is a gain-of-function mutation that leads to the formation of a hyperactive hemichannel. Overexpression of the mutant protein in human umbilical vein endothelial cells led to a loss of cellular integrity, which was rescued by carbenoxolone, a non-specific gap junction/hemichannel inhibitor. Our data suggest that GJA4 c.121G > T (p.Gly41Cys) is a potential driver gene mutation for OCVM. We propose that hyperactive hemichannel plays a role in the development of this vascular phenotype.

Atrial Fibrillation: Focus on Myocardial Connexins and Gap Junctions

Atrial fibrillation (AF) represents the most common type of clinical cardiac arrhythmia worldwide and contributes to substantial morbidity, mortality and socioeconomic burden. Aggregating evidence highlights the strong genetic basis of AF. In addition to chromosomal abnormalities, pathogenic mutations in over 50 genes have been causally linked to AF, of which the majority encode ion channels, cardiac structural proteins, transcription factors and gap junction channels. In the heart, gap junctions comprised of connexins (Cxs) form intercellular pathways responsible for electrical coupling and rapid coordinated action potential propagation between adjacent cardiomyocytes. Among the 21 isoforms of connexins already identified in the mammal genomes, 5 isoforms (Cx37, Cx40, Cx43, Cx45 and Cx46) are expressed in human heart. Abnormal electrical coupling between cardiomyocytes caused by structural remodeling of gap junction channels (alterations in connexin distribution and protein levels) has been associated with enhanced susceptibility to AF and recent studies have revealed multiple causative mutations or polymorphisms in 4 isoforms of connexins predisposing to AF. In this review, an overview of the genetics of AF is made, with a focus on the roles of mutant myocardial connexins and gap junctions in the pathogenesis of AF, to underscore the hypothesis that cardiac connexins are a major molecular target in the management of AF.

PON1 (Paraoxonase 1) Q192R gene polymorphism in ischemic stroke among North Indian population

Background:

PON1 is an High Density Lipoprotein (HDL)-associated esterase. Two common polymorphisms in the PON1 gene, Q192R and L55M substitutions, determine the inter-individual variation in PON1 activity. The association of these polymorphisms with the risk of ischemic stroke remains controversial. In the present study, the role of PON1 Q192R gene polymorphism in ischemic stroke was studied in the Indian population.

Design and Methods:

In the present case-control study, the PON1 Q192R gene polymorphism was screened in ischemic stroke patients (n: 63) and age, sex-matched controls (n: 63) using thePolymerase Chain Reaction-Restriction Segment Length Polymorphism (PCR-RFLP) method.

Results:

The mean age of stroke presentation was 58.11 ± 15.4 years. A total of 17.4% cases presented with young stroke (<45 years age) and 9.52% cases were seen to have a recurrent stroke. The distribution of -192Q/R PON1 gene polymorphism was not seen to differ between cases and controls. The traditional stroke risk factors did not have any effect on the PON1 genotype expression. A multivariate logistic regression analysis was done in order to assess an independent association of age, gender, traditional stroke risk factors, and PON1 polymorphism with acute ischemic stroke. However, neither the RR genotype nor the presence of the R allele was associated with an increase in the risk of acute ischemic stroke (OR [RR genotype]-4.76, P value: 0.24, 95% CI: 0.3497–64.8531; OR [R allele]-0.94, P value: 0.90, 95% CI: 0.3516–2.4989).

Conclusion:

PON1 Q192R gene polymorphism is not associated with an increased risk of acute ischemic stroke in the North Indian population. Further studies with a larger sample size are needed before PON1 Q192R gene polymorphism can be considered as a genetic risk factor for ischemic stroke.

Intrauterine Programming of Cardiovascular Diseases in Maternal Diabetes

Maternal diabetes is a prevalent pathology that increases the risk of cardiovascular diseases in the offspring, the heart being one of the main target organs affected from the fetal stage until the adult life. Metabolic, pro-oxidant, and proinflammatory alterations in the fetal heart constitute the first steps in the adverse fetal programming of cardiovascular disease in the context of maternal diabetes. This review discusses both human and experimental studies addressing putative mechanisms involved in this fetal programming of heart damage in maternal diabetes. These include cardiac epigenetic changes, alterations in cardiac carbohydrate and lipid metabolism, damaging effects caused by a pro-oxidant and proinflammatory environment, alterations in the cardiac extracellular matrix remodeling, and specific signaling pathways. Putative actions to prevent cardiovascular impairments in the offspring of mothers with diabetes are also discussed.

Connexins: Key Players in the Control of Vascular Plasticity and Function

Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.

The Mediterranean diet reduces the genetic risk of chromosome 9p21 for myocardial infarction in an Asian population community cohort

The interaction of genetic susceptibility and dietary habits in cardiovascular disease (CVD) remains undetermined. The purpose of this study was to investigate whether a Mediterranean dietary style modified the genetic risk of developing CVD in a Chinese cohort. A total of 2098 subjects with dietary information from a Chinese community cohort (CVDFACTS) were enrolled. Candidate genes, including SNP markers rs1333049 (CDKN2B, 9p21.3), rs17465637 (MIA3, 1q41) and rs501120 (CXCL12, 10q11.21), were genotyped to analyze the association with future CVD. The impact of dietary pattern was also analyzed according to adherence to the diet using the Mediterranean Diet Score (MDS). After an average follow-up of 7.8 years, only the C risk allele of rs1333049 at chromosome 9p21.3 was associated with a higher risk of MI with either an additive [HR = 1.78, 95% CI:1.23-2.5] or a recessive model [HR = 2.40, 95% CI: 1.42-4.04], and the CC genotype had a higher risk of developing MI (p = 0.009, log-rank test). There was no significant difference in the association of the lipid profile with future CV outcomes among the MDS tertiles. However, the high MI risk of the CC genotype in individuals consuming a less healthy diet (MDS1) (HR: 6.39, 95% CI: 1.74-23.43) significantly decreased to 2.38 (95% CI: 0.57-10.04) in individuals consuming a healthier diet (MDS3), indicating that a healthier dietary pattern (higher MDS) modified the risk of developing MI in carriers of variants in CDKN2B. In conclusion, genetic variants of CDKN2B at 9p21 were significantly associated with future MI risk in a Chinese cohort, and the genetic risk of MI could be modified by a healthier diet.

Interaction between CONNEXIN37 and PDE4D gene polymorphisms with susceptibility to ischemic stroke in Chinese population

The objective of this study was to test the relationship of several single nucleotide polymorphisms (SNPs) within phosphodiesterase 4D (PDE4D ) and connexin 37 (CONNEXIN37 ) gene additional interactions with ischemic stroke (IS) risk. The online software SNPstats was used for Hardy–Weinberg equilibrium testing. Generalized multifactor dimensionality reduction (GMDR) was employed to detect the potential interactions among CONNEXIN37 gene, PDE4D g ene, and smoking. The results indicated that the rs1764391-T and rs966221-G were correlated with higher IS risk, the corresponding ORs (95% CI) were 1.66 (1.21–2.03) and 1.48 (1.11–1.92), respectively. We also found that the first two loci including rs1764391 and rs918592, and the other two-loci including rs1764391 and smoking were significant in the GMDR model. Participants with rs1764391-CT/TT and rs918592-CT/TT genotype have the highest IS risk, compared to subjects with rs1764391-CC and rs918592-CC genotype, OR (95%CI) = 3.16 (1.83–4.45); smokers with rs1764391-CT/TT genotype also have the highest IS risk, compared to never smokers with rs1764391-CC genotype, OR (95%CI) = 2.82 (1.53–4.15), but no significant interaction combinations were found between gene and alcohol drinking. So in this study, the rs1764391-T and rs966221-G, rs1764391–rs918592 interaction, rs1764391–smoking interaction were all associated with higher IS susceptibility.

Increased ischemic stroke risk in patients with Behçet's disease: A nationwide population-based cohort study

Background

Behçet’s disease (BD) is a recurrent, multisystemic, inflammatory disorder that mainly affects blood vessels. Because recurrent inflammation of blood vessels in the brain plays a crucial role in the development of ischemic stroke, we hypothesized that patients with BD might have an elevated risk of ischemic stroke. This potential association has been suggested in a few case reports, but not epidemiological studies. Hence, the present study aimed to examine the relation between BD and subsequent ischemic stroke in Taiwan using a nationwide, population-based database.

Methods

To establish a study cohort, the longitudinal data of 306 patients newly diagnosed with BD during 2000–2010 were extracted from the National Health Insurance Research Database, Taiwan. For comparison of ischemic stroke incidence, a control cohort of 1224 subjects without BD was established using a frequency-matched ratio of 1:4 for age, sex, and pre-existing comorbidities.

Results

During the 10-year follow-up, 13 (4.2%) patients with BD and 20 (1.6%) control subjects experienced ischemic stroke. Kaplan–Meier analysis revealed the higher prevalence of ischemic stroke in the BD group (log-rank test, p = 0.001). After adjusting for comorbidities and demographic characteristics, Cox regression analysis revealed that patients with BD had a 2.77-fold risk of ischemic stroke (95% confidence interval, 1.38–5.57) compared to control subjects.

Conclusions

Patients with BD have an elevated risk of ischemic stroke. Hence, BD may affect the vascular system in the brain, resulting in a stroke event.

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.

Polymorphism of CONNEXIN37 gene is a risk factor for ischemic stroke in Han Chinese population

BACKGROUND

Stroke has a high fatality and disability rate, and is one of the main burdens to human health. It is thus very important to identify biomarkers for the development of effective approaches for the prevention and treatment of stroke. Connexin37 is an anti-inflammatory cytokine and is involved in chronic inflammation and atherosclerosis. Recent studies have found that CONNEXIN37 gene variations are associated with atherosclerosis diseases, such as coronary heart disease and stroke, but its association with stroke in distinct human populations remains to be determined. We report here the analysis of the association of the single nucleotide polymorphisms (SNPs) of CONNEXIN37 with ischemic stroke in Han Chinese population.

METHODS

Two SNPs of CONNEXIN37 gene were analyzed in 385 ischemic stroke patients and 362 hypertension control patients using ligase detection reaction (LDR) method.

RESULTS

Logistic regression analysis demonstrated that, AG and GG genotypes of SNP rs1764390 and CC genotype of rs1764391 of CONNEXIN37 were associated with an increased risk of ischemic stroke, and that G allele of rs1764390 is a risk factor for ischemic stroke. Further, we found that SNP rs1764390 and SNP rs1764391 in CONNEXIN37 were associated with ischemic stroke under additive/dominant model, and recessive/dominant model, respectively.

CONCLUSION

Our results indicate that CONNEXIN37 gene polymorphism is an ischemic stroke risk factor in Northern Han Chinese.

Association of connexin gene polymorphism with essential hypertension in Kazak and Han Chinese in Xinjiang, China

Essential hypertension (EH) is affected by both genetic and environmental factors. The polymorphism of connexin (Cx) genes is found associated with the development of hypertension. However, the association of the polymorphism of Cxs with EH has not been investigated. This study aimed to investigate the association of the polymorphism of connexin (Cx) genes Cx37, Cx40, and Cx43 with EH in Kazak and Han Chinese in Xinjiang, China. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) were used to analyze the polymorphism of Cx genes in Kazak and Han EH patients as well as their normotensive controls. The results showed that there were no significant differences in the frequencies of different three genotypes (A/A, A/G, and G/G) and A and G alleles of Cx40 rs35594137 and rs11552588 between EH patients and normotensive controls. However, in Kazak EH patients, the frequencies of three genotypes (A/A, A/G, and G/G) of Cx37 rs1630310 were 24.8%, 47.2% and 28.0%, respectively, which were significantly different from those in Han EH patients. In Han EH patients, the frequencies of the three genotypes (C/C, C/G and G/G) of Cx43 rs1925223 were 6.4%, 35.6% and 58.0%, respectively. Frequencies of the other four genotypes had no statistical differences among Kazak and Han EH patients and their normotensive controls. These results suggest polymorphisms of Cx37 rs1630310 and Cx43 rs1925223 genes may be associated with the pathogenesis of EH. Carrying Cx37 rs1630310-A or Cx43 rs1925223-G genotypes may protect against the development of EH.

Association Between a Polymorphism (rs2071214) in Baculoviral IAP Repeat Containing 5 Gene (BIRC5) and Ischemic Stroke in Korean Population

Objective

To investigate whether baculoviral inhibitor of apoptosis (IAP) repeat containing 5 gene (BIRC5) polymorphisms are associated with the development and clinical phenotypes of ischemic stroke in Korea population.

Methods

We enrolled 121 ischemic stroke patients and 291 control subjects. Ischemic stroke patients were divided into subgroups according to the scores of National Institutes of Health Stroke Survey (<6 or ≥6) and Modified Barthel Index (<60 or ≥60). Single nucleotide polymorphisms (SNPs) of BIRC5 (rs3764383 and rs2071214) were selected and genotyped by direct sequencing for all subjects. Multiple logistic regression models (codominant 1 and 2, dominant, recessive, overdominant and log-additive) were used to estimate odds ratios (ORs), 95% confidence intervals (CIs), and p-values.

Results

In analysis of stroke susceptibility, the genotype and allele frequencies of rs3764383 exhibited no difference between the control group and the ischemic stroke group. SNP rs2071214 was associated with ischemic stroke in the codominant (p=0.003), dominant (p=0.002), overdominant (p=0.005), and log-additive (p=0.008) models, respectively. The G allele frequency of rs2071214 was significantly (p=0.009) associated with susceptibility for ischemic stroke (OR, 1.57; 95% CI, 1.12–2.21). However, in the analysis for clinical phenotype, no SNP of the BIRC5 gene was found to be associated with ischemic stroke.

Conclusion

These results suggest that a missense SNP (rs2071214) of BIRC5 may be associated with the development of ischemic stroke in the Korean population.

Analysis of Connexin37 gene C1019T polymorphism and PCOS susceptibility in South Indian population: case-control study

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is a complex and multifactorial disorder believed to be the consequence of a complex interaction between genetic, immunological, and environmental factors. The main aim of this study was to investigate the association of Connexin37 (Cx37)/Gap junction alpha 4 (GJA4) gene C1019T single nucleotide polymorphism (SNP) with the susceptibility to polycystic ovarian syndrome (PCOS) in South Indian women.

STUDY DESIGN

This study comprises 98 PCOS patients and 100 healthy women without PCOS of South Indian origin. We genotyped total of seventeen selected Cx37 SNPs including C1019T (rs1764391) by polymerase chain reaction and sequencing analysis. The genotype frequency and allele distributions of cases and controls were analyzed using Fisher's exact test.

RESULTS

The genotype and allele frequencies of the C1019T polymorphism significantly differ between cases and controls. The frequencies of C/C genotype (P=0.009) and 'C' allele (P=0.002) of the C1019T polymorphism showed a significant prevalence in cases compared to controls.

CONCLUSION

Our findings suggest that the Cx37 C1019T variation may contribute to the risk of PCOS in the South Indian women.

Smoking impairs and circulating stem cells favour the protective effect of the T allele of the connexin37 gene in ischemic heart disease--A multinational study

BACKGROUND

The connexin 37 (Cx37) gene is considered to be a candidate gene for ischemic heart disease (IHD). We analyzed the association between the C1019 > T (Pro319 > Ser) variant of the Cx37 gene and IHD in patients in the Czech Republic, Croatia, Hungary and Romania with regard to the presence/absence of selected cardiovascular risk factors (RF). In a complementary study, we analyzed the association between the Cx37 gene and circulating stem and endothelial progenitor cells in healthy women.

METHODS

The study population comprised 2396 patients (663 women) with IHD. The control population comprised 2476 subjects (1, 337 women). Additionally, in 662 healthy women, the association between the Cx37 gene and circulating stem and endothelial progenitor cells was analyzed.

RESULTS

The strongest protective effect of the Cx37 T allele was detected in non-smoking patients without diabetes mellitus and hypertension (OR 0.610, 95% CI 0.377-0.990); a similar effect was found in non-smoking men (OR 0.781, 95% CI 0.628-0.971); weaker effect was found in non-smoking women (OR 0.768, 95% CI 0.560-1.050). In non-smoking healthy women, stem cells were significantly higher in TT than in CT and CC carriers (p for trend 0.011). Additionally, non-smoking TT carriers had significantly higher number of stem cells than past and current smoking TT carriers (p for trend = 0.006); no such trend was found in CT and CC carriers.

CONCLUSIONS

The protective effect of the T allele of the Cx37 gene might be strongly modified by smoking; in women, this effect could be mediated through stem cells.

Shear stress-induced atherosclerotic plaque composition in ApoE(-/-) mice is modulated by connexin37

OBJECTIVE

Shear stress patterns influence atherogenesis and plaque stability; low laminar shear stress (LLSS) promotes unstable plaques whereas oscillatory shear stress (OSS) induces more stable plaques. Endothelial connexin37 (Cx37) expression is also regulated by shear stress, which may contribute to localization of atherosclerotic disease. Moreover, Cx37 reduces initiation of atherosclerosis by inhibiting monocyte adhesion. The present work investigates the effect of Cx37 on the phenotype of plaques induced by LLSS or OSS.

METHODS

Shear stress-modifying casts were placed around the common carotid artery of ApoE(-/-) or ApoE(-/-)Cx37(-/-) mice, and animals were placed on a high-cholesterol diet for 6 or 9 weeks. Atherosclerotic plaque size and composition were assessed by immunohistochemistry.

RESULTS

Plaque size in response to OSS was increased in ApoE(-/-)Cx37(-/-) mice compared to ApoE(-/-) animals. Most plaques contained high lipid and macrophage content and a low amount of collagen. In ApoE(-/-) mice, macrophages were more prominent in LLSS than OSS plaques. This difference was reversed in ApoE(-/-)Cx37(-/-) animals, with a predominance of macrophages in OSS plaques. The increase in macrophage content in ApoE(-/-)Cx37(-/-) OSS plaques was mainly due to increased accumulation of M1 and Mox macrophage subtypes. Cx37 expression in macrophages did not affect their proliferation or their polarization in vitro.

CONCLUSION

Cx37 deletion increased the size of atherosclerotic lesions in OSS regions and abrogated the development of a stable plaque phenotype under OSS in ApoE(-/-) mice. Hence, local hemodynamic factors may modify the risk for adverse atherosclerotic disease outcomes associated to a polymorphism in the human Cx37 gene.

Association of Connexin37 C1019T with myocardial infarction and coronary artery disease: a meta-analysis

BACKGROUND

Several studies have reported that Connexin37 (Cx37) gene C1019T polymorphism is associated with myocardial infarction (MI) and coronary artery disease (CAD). However, the results remain contradictory.

METHODS AND RESULTS

Pubmed, Embase, and Cochrane library databases were systemically searched. Data were extracted by two independent reviewers and pooled odds ratio (OR) with 95% confidence interval (CI) was calculated. A total of 3498 MI cases and 3986 controls, as well as 1808 CAD cases and 1197 controls were enrolled in this meta-analysis. For MI, the overall ORs and 95% CIs of 1019T were 1.04, 0.95-1.15; and 1.02, 0.85-1.22 in dominant and recessive models, respectively. For CAD, the overall ORs and 95% CIs of 1019T were 0.61, 0.51-0.72; and 0.52, 0.43-0.62 in dominant and recessive models, respectively. No publication bias was found in this meta-analysis.

CONCLUSIONS

This meta-analysis showed that Cx37 C1019T was a risk factor for MI and a protective factor for CAD.

Mutations in cardiovascular connexin genes

Connexins (Cxs) form a family of transmembrane proteins comprising 21 members in humans. Cxs differ in their expression patterns, biophysical properties and ability to combine into homomeric or heteromeric gap junction channels between neighbouring cells. The permeation of ions and small metabolites through gap junction channels or hemichannels confers a crucial role to these proteins in intercellular communication and in maintaining tissue homeostasis. Among others, Cx37, Cx40, Cx43, Cx45 and Cx47 are found in heart, blood and lymphatic vessels. Mutations or polymorphisms in the genes coding for these Cxs have not only been implicated in cardiovascular pathologies but also in a variety of other disorders. While mutations in Cx43 are mostly linked to oculodentodigital dysplasia, Cx47 mutations are associated with Pelizaeus-Merzbacher-like disease and lymphoedema. Cx40 mutations are principally linked to atrial fibrillation. Mutations in Cx37 have not yet been described, but polymorphisms in the Cx37 gene have been implicated in the development of arterial disease. This review addresses current knowledge on gene mutations in cardiovascular Cxs systematically and links them to alterations in channel properties and disease.

The impact of acute kidney injury on the long-term risk of stroke

BACKGROUND

The incidence of acute kidney injury (AKI) requiring dialysis in hospitalized patients is increasing; however, information on the long-term incidence of stroke in patients surviving to discharge after recovering from AKI after dialysis has not been reported.

METHODS AND RESULTS

Patients that survived after recovery from dialysis-requiring AKI during index hospitalizations from 1999 to 2008 were identified in nationwide administrative registries. The risk of de novo stroke and death were analyzed with time-varying Cox proportional hazard models. The results were validated by a critical care database. We enrolled 4315 patients in the AKI-recovery group (men, 57.7%; mean age, 62.8±16.8 years) and matched 4315 control subjects as the non-AKI group by propensity scores. After a median follow-up period of 3.36 years, the incident stroke rate was 15.6 per 1000 person-years. The AKI-recovery group had higher risk (hazard ratio: 1.25; P=0.037) and higher severity of stroke events than the non-AKI group, regardless of progression to subsequent chronic kidney disease. The rate of incident stroke was not statistically different in those with diabetes alone (without AKI) and in those with AKI alone (without diabetes) after hospital discharge (P=0.086). Furthermore, the risk of mortality in the AKI-recovery group was higher than in the non-AKI group (hazard ratio: 2.4; P<0.001).

CONCLUSIONS

The patients who recovered from AKI had a higher incidence of developing incident stroke and mortality than the patients without AKI, and the impact was similar to diabetes. Our results suggest that a public health initiative is needed to enhance postdischarge follow-up of renal function and to control the subsequent incidence of stroke among patients who recover from AKI after dialysis.

Association of oxysterol binding protein-related protein 9 polymorphism with cerebral infarction in Hunan Han population

BACKGROUND

Oxysterol binding protein-related protein 9 (ORP9) may be related to the pathogenesis of cerebral infarction since it is closely related with glucose and lipid metabolism. The present study was designed to investigate the genetic relationship between ORP9 gene polymorphisms and cerebral infarction (CI) in Hunan Han population.

METHODS

Total 544 cerebral infarction patients (60.0 ± 10.3 years) and 284 healthy controls (59.0 ± 9.5 years) were enrolled. Sociodemographic and clinical data of the subjects, such as age, gender, body mass index, smoking, drinking, diabetes mellitus, hypertension, systolic and diastolic blood pressures, fasting blood glucose, triglycerides, total cholesterol, low-density and high-density lipoprotein were recorded, and two single-nucleotide polymorphisms (SNPs) of ORP9 gene including rs856600 and rs768529 with high mutation annotation format (MAF) values of 0.103 and 0.485 were studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

No statistical difference was observed in allele distributions and frequencies of the two SNPs between control and CI groups. However, the percentage of atherosclerosis in CI group was significantly higher than that in the control group (p < 0.001). The frequencies of the TT genotype and T allele of rs768529 were significantly higher in patients with vulnerable plaque than those in patients with stable plaque (p < 0.001, p = 0.002). Logistic association analysis showed no correlations between cerebral infarction and different alleles (p > 0.05).

CONCLUSION

T allele of rs768529 may be a risk factor for the formation of the carotid vulnerable plaque in Chinese Hunan Han population.

Exposure to Maternal Diabetes in Utero and DNA Methylation Patterns in the Offspring

Perturbations in early life environments, including intrauterine exposure to maternal gestational diabetes (GDM), are hypothesized to lead to metabolic imprinting resulting in increased risk of cardiometabolic outcomes later in life. We aimed to 1) identify candidate genes and biological pathways associated with differentially methylated regions (DMRs) in relation to exposure to GDM in utero and, 2) using mediation analysis, more definitively investigate the potential for mediation of the effect of exposure to maternal diabetes in utero on cardiometabolic traits in childhood risk through our identified DMRs. Genome-wide methylation analysis of peripheral blood mononuclear cell's DNA was conducted in 21 healthy children, ages 8-12 years. P-values from multiple linear regression analyses for >27,000 CpG sites were ranked to identify DMRs between the exposure groups. Among the top 10 ranked DMRs, we identified several genes, including NPR1, PANK1, SCAND1, and GJA4, which are known to be associated with cardiometabolic traits. Gene enrichment analysis of the top 84 genes, each with p<=0.005, identified the ubiquitin proteasome system (UPS) as the most enriched biological pathway (p = 0.07). The UPS pathway reflects biological processes known to be associated with endothelial function, inflammation, lipid metabolism, insulin resistance and β-cell apoptosis, whose derangements are central to the pathogenesis of cardiometabolic diseases. Increased methylation of PYGO1 and CLN8 had the greatest relative mediation effect (RME = 87%, p=0.005 and RME=50%, p=0.01) on the impact of exposure to maternal diabetes in utero on VCAM-1 levels in the offspring. Multiple candidate genes and the UPS were identified for future study as possible links between exposure to maternal gestational diabetes in utero and adverse cardiometabolic traits in the offspring. In particular, increased methylation of PYGO1 and CLN8 may be biological links between intrauterine exposure to maternal diabetes and significantly increased VCAM-1 levels in the offspring.

GLAD4U: deriving and prioritizing gene lists from PubMed literature

Background

Answering questions such as "Which genes are related to breast cancer?" usually requires retrieving relevant publications through the PubMed search engine, reading these publications, and creating gene lists. This process is not only time-consuming, but also prone to errors.

Results

We report GLAD4U (Gene List Automatically Derived For You), a new, free web-based gene retrieval and prioritization tool. GLAD4U takes advantage of existing resources of the NCBI to ensure computational efficiency. The quality of gene lists created by GLAD4U for three Gene Ontology (GO) terms and three disease terms was assessed using corresponding "gold standard" lists curated in public databases. For all queries, GLAD4U gene lists showed very high recall but low precision, leading to low F-measure. As a comparison, EBIMed's recall was consistently lower than GLAD4U, but its precision was higher. To present the most relevant genes at the top of a list, we studied two prioritization methods based on publication count and the hypergeometric test, and compared the ranked lists and those generated by EBIMed to the gold standards. Both GLAD4U methods outperformed EBIMed for all queries based on a variety of quality metrics. Moreover, the hypergeometric method allowed for a better performance by thresholding genes with low scores. In addition, manual examination suggests that many false-positives could be explained by the incompleteness of the gold standards. The GLAD4U user interface accepts any valid queries for PubMed, and its output page displays the ranked gene list and information associated with each gene, chronologically-ordered supporting publications, along with a summary of the run and links for file export and functional enrichment and protein interaction network analysis.

Conclusions

GLAD4U has a high overall recall. Although precision is generally low, the prioritization methods successfully rank truly relevant genes at the top of the lists to facilitate efficient browsing. GLAD4U is simple to use, and its interface can be found at: http://bioinfo.vanderbilt.edu/glad4u.

Association between C1019T polymorphism of the connexin37 gene and coronary heart disease in patients with in-stent restenosis

Studies have shown that a C1019T polymorphism of the gene encoding the gap junction protein connexin37 is associated with coronary artery disease (CAD). The aim of the present study was to explore the association between the C1019T polymorphism in the connexin37 gene and CAD patients with in-stent restenosis (ISR). A total of 532 patients who had undergone coronary stenting and coronary angiography at least three months after the procedure were divided according to a clinical diagnosis standard into two groups which were ISR (n=67) and no in-stent restenosis (NISR; n=465) groups. A further 501 healthy individuals were controls. The subjects were genotyped by DNA sequencing. The results demonstrated the following: i) connexin37 gene 1019 sites in the population were distributed by polymorphism into three genetic types (CC, TC and TT types). The distribution frequency of the healthy control, ISR and NISR groups conformed to the Hardy-Weinberg genetic balance rule; ii) in comparison with the healthy controls, the frequency of the connexin37 C allele was higher in the CAD patients (57.05% vs. 41.32%; OR, 1.89; 95% CI, 1.58–2.25; P<0.01). The frequency of the C carriers (CC+TC) was 65.47% in the healthy controls, vs. 79.32% in CAD patients (P<0.01). The CAD risk was significantly increased in the carriers of the C allele (CC+TC) compared with TT homozygotes (OR, 2.03; 95% CI, 1.53–2.80; P<0.01). Stratified analysis demonstrated that a significant difference existed in the frequency of C carriers between the male CAD patients and healthy controls (79.63% vs. 72.45%; OR, 1.48; 95% CI, 1.06–2.09, P=0.02), as well as in the female CAD patients (78.00% vs. 51.50%; OR, 3.34; 95% CI, 1.90–5.86; P<0.01). In the female and male CAD patients, the frequency of the connexin37 C allele was higher than in the healthy controls (male: χ²=12.67, P<0.01; female: χ²=50.20, P<0.01); iii) compared with the NISR group, the frequencies of the connexin37 C allele and C carriers (CC+TC) were significantly higher in the ISR group (frequency of C allele: 72.39% vs. 54.84%; P<0.01; frequency of C carriers: 89.55% vs. 77.85%; P=0.03). Compared with TT homozygotes, the restenosis risk was significantly increased in the carriers of the C allele (CC+TC; OR, 2.44; 95% CI, 1.08–5.50). Subsequent stratified analysis revealed that the frequency of the C allele was significantly higher in the male ISR group than in the male NISR group (78.57% vs. 52.66%; OR, 3.30; 95% CI, 2.05–5.29; P<0.01). The restenosis risk was ∼four-fold higher in the C carriers (CC+TC) than in the TT homozygotes (OR, 3.74; 95% CI, 1.32–10.64). However in the female population, there was no difference in the ISR risk between the carriers of the C allele (CC+TC) and the TT homozygotes (P=0.70). In summary, the C allele of the connexin37 gene is not only is associated with the susceptibility to CAD, but also associated with restenosis following coronary stenting in the population studied herein, particularly the male population.

The association of tooth scaling and decreased cardiovascular disease: a nationwide population-based study

OBJECTIVE

Poor oral hygiene has been associated with an increased risk for cardiovascular disease. However, the association between preventive dentistry and cardiovascular risk reduction has remained undetermined. The aim of this study is to investigate the association between tooth scaling and the risk of cardiovascular events by using a nationwide, population-based study and a prospective cohort design.

METHODS

Our analyses were conducted using information from a random sample of 1 million persons enrolled in the nationally representative Taiwan National Health Insurance Research Database. Exposed individuals consisted of all subjects who were aged ≥ 50 years and who received at least 1 tooth scaling in 2000. The comparison group of non-exposed persons consisted of persons who did not undergo tooth scaling and were matched to exposed individuals using propensity score matching by the time of enrollment, age, gender, history of coronary artery disease, diabetes, hypertension, and hyperlipidemia.

RESULTS

During an average follow-up period of 7 years, 10,887 subjects who had ever received tooth scaling (exposed group) and 10,989 age-, gender-, and comorbidity-matched subjects who had not received tooth scaling (non-exposed group) were enrolled. The exposed group had a lower incidence of acute myocardial infarction (1.6% vs 2.2%, P<.001), stroke (8.9% vs 10%, P=.03), and total cardiovascular events (10% vs 11.6%, P<.001) when compared with the non-exposed group. After multivariate analysis, tooth scaling was an independent factor associated with less risk of developing future myocardial infarction (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.57-0.85), stroke (HR, 0.85; 95% CI, 0.78-0.93), and total cardiovascular events (HR, 0.84; 95% CI, 0.77-0.91). Furthermore, when compared with the non-exposed group, increasing frequency of tooth scaling correlated with a higher risk reduction of acute myocardial infarction, stroke, and total cardiovascular events (P for trend<.001).

CONCLUSION

Tooth scaling was associated with a decreased risk for future cardiovascular events.

PON gene polymorphisms and ischaemic stroke: a systematic review and meta analysis

BACKGROUND

Paraoxonase is known to play an important role in the pathophysiology of atherosclerosis. Genetic variants of the paraoxonase gene have been implicated as risk factors for atherosclerotic diseases such as coronary artery disease, but individual genetic association studies examining the relationship between the paraoxonase gene polymorphisms and ischaemic stroke have yielded inconsistent results.

AIM

This study aimed to evaluate the association between the paraoxonase gene variants and ischaemic stroke using systematic review with meta-analysis.

METHODS

Relevant studies were identified by searching English and Chinese databases extensively. Allele and genotype frequencies for each included study were extracted. The odds ratio was calculated using a random-effects or fixed-effects model. A Q statistic was used to evaluate homogeneity, and Egger's test and funnel plot were used to assess publication bias.

RESULTS

A total of 28 studies were included and identified for the current meta-analysis. It was found that the R allele or RR genotype of paraoxonase 1 Q192R polymorphism had an increased risk for ischaemic stroke in the general population (192R allele: odds ratio: 1·21, 95% confidence interval: 1·08-1·35, P = 0·0009 and 192RR genotype: odds ratio: 1·25, 95% confidence interval: 1·06-1·49, P = 0·009 in general population, respectively), but there was no significant association between other genetic variants of paraoxonase gene and ischaemic stroke.

CONCLUSIONS

Existing evidence indicates that the Q192R polymorphism (the R allele and RR genotype) is associated with an increased risk of ischaemic stroke in the general population. Future studies with larger sample sizes will be necessary to confirm the present results.

Association between polymorphisms in the adiponectin gene and cardiovascular disease: a meta-analysis

Background

Previous studies have examined the associations between polymorphisms of adiponectin gene (ADIPOQ) and cardiovascular disease (CVD), but those studies have been inconclusive. The aim of this study was to access the relationship between three single nucleotide polymorphisms (SNPs), +45 T > G (rs2241766), +276 G > T (rs1501299) and -11377 C > G (rs266729) in ADIPOQ and CVD.

Methods

A comprehensive search was conducted to identify all studies on the association of ADIPOQ gene polymorphisms with CVD risk. The fixed and random effect pooled measures (i.e. odds ratio (OR) and 95% confidence interval (CI)) were calculated in the meta-analysis. Heterogeneity among studies was evaluated using Q test and the I². Publication bias was estimated using modified Egger’s linear regression test.

Results

Thirty-seven studies concerning the associations between the three polymorphisms of ADIPOQ gene and CVD risk were enrolled in this meta-analysis, including 6,398 cases and 10,829 controls for rs2241766, 8,392 cases and 18,730 controls for rs1501299 and 7,835 cases and 14,023 controls for rs266729. The three SNPs were significantly associated with CVD, yielding pooled ORs of 1.22 (95%CI: 1.07, 1.39; P = 0.004), 0.90 (95%CI: 0.83, 0.97; P = 0.007) and 1.09(95%CI: 1.01, 1.17; P = 0.032) for rs2241766, rs1501299 and rs266729, respectively. Rs2241766 and rs1501299 were significantly associated with coronary heart disease (CHD), yielding pooled ORs of 1.29 (95%CI: 1.09, 1.52; P = 0.004) and 0.89 (95%CI: 0.81, 0.99; P = 0.025), respectively. The pooled OR for rs266729 and CHD was 1.09 (95%CI: 0.99, 1.19; P = 0.090). Significant between-study heterogeneity was found in our meta-analysis. Evidence of publication bias was observed in the meta-analysis.

Conclusions

The present meta-analysis showed that the associations between rs2241766, rs1501299 and rs266729 in the ADIPOQ and CVD were significant but weak. High quality studies are still needed to confirm the associations, especially for rs2241766.

Connexins in atherosclerosis

Atherosclerosis, a chronic inflammatory disease of the vessel wall, involves multiple cell types of different origins, and complex interactions and signaling pathways between them. Autocrine and paracrine communication pathways provided by cytokines, chemokines, growth factors and lipid mediators are central to atherogenesis. However, it is becoming increasingly recognized that a more direct communication through both hemichannels and gap junction channels formed by connexins also plays an important role in atherosclerosis development. Three main connexins are expressed in cells involved in atherosclerosis: Cx37, Cx40 and Cx43. Cx37 is found in endothelial cells, monocytes/macrophages and platelets, Cx40 is predominantly an endothelial connexin, and Cx43 is found in a large variety of cells such as smooth muscle cells, resident and circulating leukocytes (neutrophils, dendritic cells, lymphocytes, activated macrophages, mast cells) and some endothelial cells. Here, we will systematically review the expression and function of connexins in cells and processes underlying atherosclerosis. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.

Lack of association between a functional genetic variant of connexin 37 and ischemic stroke in a Taiwanese population

INTRODUCTION

Connexin 37, encoded by the GJA4 gene, protects against atherosclerosis. A recent study reported an association between polymorphism rs1764391 at GJA4 and ischemic stroke in a Chinese population. We aimed to replicate this result.

MATERIALS AND METHODS

A total of 958 ischemic stroke patients and 2196 controls were enrolled for the study. All participants were Chinese residing in Taiwan. Logistic regression analysis with adjustment for traditional risk factors was used to estimate the genetic effect. We also performed stratification analyses by sex and stroke subtypes. Literature reviews were conducted for available genetic association studies investigating rs1764391 and cardiovascular phenotypes.

RESULTS

We did not find any significant association for overall stroke (p=0.87) or from any subset analyses. Eight studies addressing the associations between rs1764391 and cardiovascular phenotypes had a sample size greater than 1000. Including the present study, five out of the eight large-scale studies found no association.

CONCLUSIONS

GJA4 polymorphism is not associated with stroke risk in the Taiwanese population.

Increased risk of ischemic stroke in patients with systemic lupus erythematosus: a nationwide population-based study

BACKGROUND

Systemic lupus erythematosus (SLE) has been reported to be associated with an increased risk of cardiovascular disease. However, most studies have been criticized for either a small sample size or the lack of a prospective control. Our study investigated the relationship of SLE and the subsequent development of ischemic stroke using a nationwide, population-based database in an Asian population.

METHODS

From 2000 to 2007, we identified a study cohort consisting of a total of 11,637 newly diagnosed SLE patients using the National Health Insurance Research Database in Taiwan. A control cohort of 58,185 subjects without SLE, matched for age, gender, and comorbidities were selected for comparison to observe the occurrence of ischemic stroke in these two groups.

RESULTS

During a follow-up period of up to 7 years, ischemic stroke developed in 258 (2.22%) of the patients with SLE and in 873 (1.5%) of patients in the comparison cohort. Kaplan-Meier analysis also revealed a tendency of SLE patients toward ischemic stroke development (log rank test, p = 0.001). After Cox model adjustment for patients' demographic characteristics and selected comorbidities, patients with SLE were found to have a 1.67-fold (95% CI, 1.45 to 1.91) higher risk of developing ischemic stroke.

CONCLUSION

Patients with SLE have an increased risk of stroke.

Polymorphisms of integrin, alpha 6 contribute to the development and neurologic symptoms of intracerebral hemorrhage in korean population

OBJECTIVE

The extracellular matrix (ECM) and cell adhesion molecules play crucial roles in angiogenesis, apoptosis, thrombosis, and inflammation, and also contribute to the pathogenesis of stroke. Integrin, alpha 6 (ITGA6) is a member of ECM adhesion receptors. We investigated whether two single nucleotide polymorphisms (SNPs) (rs11895564, Ala380Thr; rs2293649, Asp694Asp) of ITGA6 were associated with the development and clinical phenotypes of intracerebral hemorrhage (ICH) and ischemic stroke (IS).

METHODS

We enrolled 199 stroke (78 ICH and 121 IS) and 291 control subjects. Stroke patients were divided into subgroups according to the scores of the National Institutes of Health Stroke Survey (NIHSS, <6 and ≥6) and Modified Barthel Index (MBI, <60 and ≥60). SNPStats, SNPAnalyzer, and Helixtree programs were used to calculate odds ratios, 95% confidence intervals, and p values. Multiple logistic regression models were used to analyze genetic data.

RESULTS

A missense SNP rs11895564 was associated with the development of ICH (p=0.026 in codominant2, p=0.013 in recessive, p=0.02 in log-additive models; p=0.041 in allele distributions). The A allele frequency of rs11895564 was higher in the ICH group (13.5%) than in the control group (8.1%). In the clinical phenotypes, rs11895564 and rs2293649 showed significant associations in the MBI scores of IS (p=0.014 in codominant1 model; p=0.02 in allele distributions) and NIHSS scores of ICH (p=0.017 in codominant2, p=0.035 in recessive, p=0.035 in log-additive models), respectively.

CONCLUSION

These results suggest that ITGA6 may be associated with the development and clinical phenotypes of stroke in Korean population.

Association Between Mycoplasma Pneumonia and Increased Risk of Ischemic Stroke

Background and Purpose—

Infections have been hypothesized to play a role in vascular disease. The association between Mycoplasma pneumoniae (MP) infection and ischemic stroke remained undetermined.

Methods—

A total of 1094 patients with MP infection were enrolled as the study group and compared with 5168 sex-, age-, and comorbidity-matched subjects without MP, to be followed up prospectively from January 2003 to December 2007 for development of ischemic stroke.

Results—

During a maximum 5-year follow-up period, 49 patients with ischemic stroke were identified. Subjects with MP infection were significantly associated with increased risk of ischemic stroke compared with controls (1.10% versus 0.72%, respectively; P =0.01). The logrank test showed that patients with MP had significantly higher incidence of stroke development than did those without MP ( P =0.046). After Cox model adjustment for risk factors and comorbidities, MP infection was still independently associated with increased risk of stroke (hazard ratio [HR], 2.07; 95% CI, 1.05–4.03).

Conclusions—

We conclude that MP infection is independently associated with risk of subsequent ischemic stroke development.