Coexistence of angiotensin II type-1 receptor A1166C and angiotensin-converting enzyme D/D polymorphism suggests susceptibility for small-vessel-associated ischemic stroke

Genetic Variants Associated with High Susceptibility of Premature Ischemic Stroke

Background

Several polymorphisms had been associated with an increased risk of ischemic stroke, but results are inconclusive. The aim of this study was to examine the association between AGTR1 A1166C and TSP-1 N700S polymorphisms and ischemic stroke in a young Mexican population.

Methods

In a case-control study, 250 patients ≤ 45 years of age with ischemic stroke and 250 controls matched by age and gender were included. The polymorphisms were determined in all participants by polymerase chain reaction.

Results

There were statistical differences in genotype distribution (p = 0.01) and allele frequency (p = 0.001) of AGTR1 A1166C polymorphism. In contrast, there was a similar genotype distribution (p = 0.96) and allele frequency (p = 0.76) of the TSP1 N700S genetic variant between groups. Hypertension (p = 0.03), smoking (p = 0.02), and family history of atherothrombotic disease (p = 0.04) were associated with stroke, but not diabetes (p = 0.30) and dyslipidemia (p = 0.08).

Conclusions

This is the first study in Mexican population to explore several genetic variants in young patients with ischemic stroke. Our results suggest that polymorphisms in the renin-angiotensin-aldosterone system could contribute to premature hypertension, endothelial dysfunction, atherothrombosis, vasoconstriction, smooth muscle cell migration, and proliferation. In contrast, polymorphisms in the coagulation factors are not associated with ischemic stroke. Environmental factors such as diabetes and dyslipidemia could be less important in the pathogenesis of ischemic stroke at a young age. We suggest that those polymorphisms should be determined in individuals with a family history of thrombosis to avoid the stroke development. Therefore, genotype-environmental combination could determine several possible phenotypes at different moments in life.

The Renin-Angiotensin System: A Key Role in SARS-CoV-2-Induced COVID-19

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), was first identified in Eastern Asia (Wuhan, China) in December 2019. The virus then spread to Europe and across all continents where it has led to higher mortality and morbidity, and was declared as a pandemic by the World Health Organization (WHO) in March 2020. Recently, different vaccines have been produced and seem to be more or less effective in protecting from COVID-19. The renin-angiotensin system (RAS), an essential enzymatic cascade involved in maintaining blood pressure and electrolyte balance, is involved in the pathogenicity of COVID-19, since the angiotensin-converting enzyme II (ACE2) acts as the cellular receptor for SARS-CoV-2 in many human tissues and organs. In fact, the viral entrance promotes a downregulation of ACE2 followed by RAS balance dysregulation and an overactivation of the angiotensin II (Ang II)-angiotensin II type I receptor (AT1R) axis, which is characterized by a strong vasoconstriction and the induction of the profibrotic, proapoptotic and proinflammatory signalizations in the lungs and other organs. This mechanism features a massive cytokine storm, hypercoagulation, an acute respiratory distress syndrome (ARDS) and subsequent multiple organ damage. While all individuals are vulnerable to SARS-CoV-2, the disease outcome and severity differ among people and countries and depend on a dual interaction between the virus and the affected host. Many studies have already pointed out the importance of host genetic polymorphisms (especially in the RAS) as well as other related factors such age, gender, lifestyle and habits and underlying pathologies or comorbidities (diabetes and cardiovascular diseases) that could render individuals at higher risk of infection and pathogenicity. In this review, we explore the correlation between all these risk factors as well as how and why they could account for severe post-COVID-19 complications.

Association Between the Angiotensin-Converting Enzyme I/D Polymorphism and Risk of Cerebral Small Vessel Disease: A Meta-Analysis Based on 7186 Subjects

INTRODUCTION

Cerebral small vessel disease (CSVD) causes a quarter of all strokes and is the most common pathology underlying vascular dementia. However, the mechanism of CSVD remains unclear. Numerous studies have investigated whether the angiotensin-converting enzyme (ACE) intersection/deletion (I/D) polymorphism influences the risk of CSVD, but the results are controversial.

METHODS

We searched English and Chinese databases and calculated the odds ratio (OR) and 95% confidence interval (CI) to examine the existence of genetic associations between the ACE I/D polymorphism and the risk of CSVD. All relevant studies were screened and meta-analyzed using Review Manager 5.4.

RESULTS

A total of 27 studies involving 7,186 subjects were identified for the meta-analysis. The results of five genetic models showed a significantly increased risk of CSVD (allelic, OR=1.30; recessive, OR=1.41; dominant, OR=1.34; homozygous, OR=1.55 and heterozygous OR=1.22) in the overall analysis. Furthermore, in subgroup analysis, increased CSVD risks were also observed in Asian and Caucasian populations. We also found no relationship between ACE I/D and leukoaraiosis (LA) in patients with lacunar infarction (LI).

CONCLUSION

The ACE I/D polymorphism was positively associated with CSVD in both populations. However, this polymorphism did not increase the risk of LA in LI patients.

Gene polymorphisms of angiotensin-converting enzyme and angiotensinogen and risk of idiopathic ischemic stroke

OBJECTIVE

The renin-angiotensin system (RAS) is a hormonal signaling mechanism implicated in the atherosclerosis and regulation of blood pressure. Angiotensin-converting enzyme (ACE) a key enzyme in the RAS, plays important roles in vascular remodeling atherosclerosis, and ischemic stroke. The aim of this study was to examine the possible contribution of the I/D in the ACE gene, M235T and T174M in the angiotensinogen (AGT) gene polymorphisms with ischemic stroke in young Mexican population.

MATERIALS AND METHODS

A total of 224 patients with diagnosis of idiopathic ischemic stroke ≤45 years of age, and 224 controls matched by age and gender, were recruited from 2006 and 2016. The I/D, M235T and T174M polymorphisms were determined in all participants by PCR-RFLP.

RESULTS

There was a significant difference in the M235T genotype distribution (p = 0.01) and allele frequency between two groups (p = 0.01). Also, we found a significant difference in the T174M genotype distribution (p = 0.01) and the allele frequency between groups; (p = 0.02). In contrast, in I/D polymorphism, there was a similar genotype distribution; (p = 0.20) and allele distribution (p = 0.20). There were independent factors for ischemic stroke: M235T and T174M polymorphisms, smoking, hypertension, and familial history of atherothrombotic disease. The AGT levels were increased in the group of patients with stroke compared with the control group, but the AGT levels were not influenced by the allele or genotype in each polymorphism.

CONCLUSIONS

The M235T and T174M polymorphisms represented an increased risk for stroke in young Mexican individuals. In contrast, the I/D was not associated with in the same group of patients. The AGT levels were higher in the acute phase of stroke, but it was not determined by the polymorphisms.

Post-stroke cognitive decline: an update and perspectives for clinical research

The close relationship between stroke and dementia is an important health issue. Ischaemic stroke can facilitate the onset of vascular dementia as well as aggravate pre-existing cognitive decline. The onset of cognitive decline may become manifest immediately following the onset of ischaemic stroke, but often there is a delay in the development of cognitive decline after a stroke. This delay can be seen as a therapeutic time window allowing interventions to be applied to preserve cognition following stroke. Both neurodegenerative and vascular mechanisms are activated and probably result in overlapping processes within the neurovascular unit. This review focuses on the incidence and prevalence of cognitive decline following stroke, predisposing stroke aetiologies, pre-stroke decline, imaging factors and biomarkers. Outcomes are discussed in relation to timing of assessment and neuropsychological tests used for evaluation of cognitive decline in ischaemic stroke patients. Including such tests in routine evaluations of stroke patients after some weeks or months is recommended. Finally, an outlook on ongoing and planned intervention trials is added and some recommendations for future research are proposed.

Angiotensin-converting enzyme gene insertion/deletion polymorphism and small vessel cerebral stroke in Indian population

Background. Hypertension is an established risk factor for small-vessel cerebral stroke and the renin-angiotensin system plays an important role in the maintenance of blood pressure. We aimed at evaluating the contribution of the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism to the risk of small-vessel stroke in south Indian population. Materials and Methods. We investigated 128 patients diagnosed with small-vessel stroke and 236 age, and gender-matched healthy controls. ACE I/D polymorphism was detected by polymerase chain reaction. Results. Hypertension was significantly more prevalent in the patient group and was associated with 6-fold increase in risk for stroke. ACE genotypes were in Hardy-Weinberg equilibrium in both patients and controls. Prevalence of DD, ID, and II genotypes in cases (34.4%, 43.7%, and 28%) did not differ significantly from controls (31.8%, 43.2%, and 25%). The polymorphism was not associated with small-vessel stroke (OR: 1.34; 95% CI: 0.52–1.55). However, diastolic blood pressure was associated with the ACE I/D genotypes in the patients. (DD; 90.2 ± 14.2> ID; 86.2 ± 11.9> II; 82.3 ± 7.8 mm Hg,  P = 0.047). Conclusion. Our study showed that hypertension, but not ACE I/D polymorphism, increased the risk of small-vessel stroke.

Lack of association of genetic polymorphisms of angiotensin converting enzyme 1 and angiotensin II type 1 receptor with breast cancer risk in Iranian population

We aimed to investigate the association of insertion/deletion (I/D) and A1166C polymorphisms of angiotensin I converting enzyme 1 and angiotensin II type 1 receptor genes, respectively and their combination on breast cancer risk in an Iranian population. A case-control study (70 cases, 70 controls) was performed on an Iranian population. The I/D and A1166C polymorphisms were analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism PCR, respectively. The results revealed no significant difference between cases and controls in I/D (p = 0.14) and A1166C (p = 0.94) polymorphisms after adjustment for breast cancer known risk factors. In combined genotype analysis, considering DD and AA genotypes as low-risk genotypes, women with one and two high-risk genotypes (one high-risk genotype: adjusted odds ratio (OR), 1.24; two high-risk genotypes: adjusted OR, 1.97) were at higher risk for breast cancer. Also, the highest risk for breast cancer was seen in a subgroup of postmenopausal women carriers of two high-risk genotypes (adjusted OR, 2.41). In conclusion, I/D and A1166C polymorphisms are not significantly associated with breast cancer risk in the Iranian population; however, the combination of these two polymorphisms seems to have a synergic effect on the risk of breast cancer particularly in postmenopausal women, which may deserve consideration in large-scale case-control studies.

Frequency of angiotensin II type 1 receptor gene polymorphism in Turkish acute stroke patients

This study was performed in acute stroke patients in the Turkish population to determine the frequency of the A1166C polymorphism in the AT1 gene and to examine the role of this polymorphism in acute stroke development. In this study, 257 genomic DNA samples were analysed (from 206 acute stroke patients and 51 healthy individuals). Genomic DNA was prepared from peripheral blood using the salt-extraction method. The presence of the A1166C polymorphism in the AT1 gene was determined using the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. PCR products were separated by 2% agarose gel electrophoresis and visualized by a charge-coupled device (CCD) camera. In this study, the allele frequency at the A1166C position was 92% A and 8% C for control and 97% A and 3% C for patients. This difference in allele frequency between the control group and the patient group was not statistically significant. However, genotype and allele frequencies showed a significant difference (P < 0.001) in the control and the patient groups. The results of this study show no relationship between the A1166C polymorphism in the AT1 gene and acute stroke in the Turkish population.

Association between angiotensin II type 1 receptor gene polymorphisms and ischemic stroke: a meta-analysis

BACKGROUND

Angiotensin II type 1 receptor (AT1R) gene A1166C polymorphisms have been inconsistently associated with ischemic stroke risk. We examined these associations by performing a meta-analysis.

MATERIALS AND METHODS

We performed a search of articles published from January 2000 to October 2010 using the following keywords: {(angiotensin II type 1 receptor) or (AT1R) or (AGT1R)} and {(stroke) or (cerebral infarction) or (cerebral embolism)}. Eleven studies testing the association between AT1R gene A1166C polymorphisms and ischemic stroke risk were included. The analyses were performed using the Review Manger 5.0.25 software package.

RESULTS

The combined data showed no association between the AT1R 1166 AC/CC and ischemic stroke risk (odds ratio (OR) = 1.08, 95% confidence interval (CI) 0.87-1.34, p = 0.49). In the subgroup analyses, the association was also not significant among the White populations (OR = 1.10, 95% CI 0.88-1.38, p = 0.39) or the Asian populations (OR = 0.99, 95% CI 0.56-1.77, p = 0.98).

LIMITATIONS

Heterogeneity and publication bias existed in this meta-analysis, which might have affected the analysis result.

CONCLUSION

The present meta-analysis suggests that the AT1R gene A1166C polymorphisms are not associated with susceptibility to ischemic stroke.

Angiotensin I - Converting Enzyme Gene Polymorphism and Activity in Patients with Ischemic Stroke

The possible association of ACE polymorphism with ischemic stroke (IS) was evaluated in 65 patients with IS and 330 age and BMI-matched controls. ACE genotypes were determined by polymerase chain reaction (PCR). There was no significant difference in ACE genotype/allele frequencies between case and control group (p>0.05). Patients with D allele had 4,7 times higher risk for large vessel IS than healthy persons D allele possessors. Persons with D allele had 9.2 times higher risk for large vessel disease than small vessel disease. These data suggest a possible association of ACE gene polymorphism with pathogenesis of large vessel IS.

Three periods of one and a half decade of ischemic stroke susceptibility gene research: lessons we have learned

Candidate gene association studies, linkage studies and genome-wide association studies have highlighted the role of genetic factors in the development of ischemic stroke. This research started over a decade ago, and can be separated into three major periods of research. In the first wave classic susceptibility markers associated with other diseases (such as the Leiden mutation in Factor V and mutations in the prothrombin and 5,10-methylenetetrahydrofolate reductase (MTHFR) genes) were tested for their role in stroke. These first studies used just a couple of hundred samples or even less. The second and still ongoing period bridges the two other periods of research and has led to a rapid increase in the spectrum of functional variants of genes or genomic regions, discovered primarily in relation to other diseases, tested on larger stroke samples of clinically better stratified patients. Large numbers of these alleles were originally discovered by array-based genome-wide association studies. The third period of research involves the direct array screening of large samples; this approach represents significant progress for research in the field. Research into susceptibility genes for stroke has taught us that careful stratification of patients is critical, that susceptibility alleles are often shared between diseases, and that not all susceptibility factors that associate with clinical traits that are themselves risk factors for stroke (such as increase of triglycerides) necessarily represent susceptibility for stroke. Research so far has been mainly focused on large- and small-vessel associated stroke, and knowledge on other types of stroke, which represent much smaller population samples, is still very scarce. Although some susceptibility allele tests are on the palette of some direct-to-consumer companies, the clinical utility and clinical validity of these test results still do not support their use in clinical practice.

Angiotensin receptor gene polymorphisms and 2-year change in hyperintense lesion volume in men

This longitudinal study examined the relationship between 2-year change in white matter hyperintense lesion (WML) volume and polymorphisms in genes coding for the angiotensin-II type 1 and type 2 receptors, AGTR1 A1166C and AGTR2 C3123A, respectively. 137 depressed and 94 non-depressed participants aged >or=60 years were enrolled. Standard clinical evaluations were performed on all participants and blood samples obtained for genotyping. 1.5-T MRI (magnetic resonance imaging) data were obtained at baseline and approximately 2 years later. These scans were processed using a semi-automated segmentation process, which allowed for the calculation of WML volume at each time point. Statistical models were tested for the relationship between change in WML volume and genotype, while also controlling for age, sex, diagnostic strata, baseline WML volume and comorbid cerebrovascular risk factors. In men, AGTR1 1166A allele homozygotes exhibited significantly less change in WML volume than 1166C carriers. We also found that men reporting hypertension (HTN) with the AGTR2 3123C allele exhibit less change in WML volume than hypertensive men with the 3123A allele, or men without HTN. There were no significant relationships between these polymorphisms and change in WML volume in women. No significant gene-gene or gene-depression interactions were observed. Our results parallel earlier observed gender differences of the relationship between other renin-angiotensin system polymorphisms and HTN. Further work is needed to determine whether these observed relationships are secondary to polymorphisms affecting response to antihypertensive medication, and whether antihypertensive medications can slow WML progression and lower the risk of morbidity associated with WMLs.

Pathomechanism of leukoaraiosis: a molecular bridge between the genetic, biochemical, and clinical processes (a mitochondrial hypothesis)

Ischemic demyelination in the white matter of the brain is a frequent clinical entity. In neuroimaging terms, it is referred to as leukoaraiosis (LA). LA can reflect a broad public health problem, which is caused by a cognitive impairment ranging from mild slowness of thinking to full-blown subcortical dementia. One-quarter of subjects aged 65 yr or over are affected by some degree of white matter changes. There are a number of genetic factors that can be associated with circulatory disturbances of the white matter of the brain. A slight chronic hypoperfusion or an endothelial dysfunction associated with unfavorable genetic variations such as methylenetetrahydrofolate reductase C677T variation and angiotensin-converting enzyme I/D polymorphism then may lead indirectly to a malfunction of the molecular cross-talk between the nucleus and the mitochondria. This results in a decrease in the production of energy in the glia cells and thereby the beginning of demyelination. From another aspect, the presence of either the apolipoprotein E 2 or 4 alleles may cause an increased vulnerability to a slight chronic hypoperfusion of the white matter by reducing the range of mechanical and chemical flexibility of the glial cytoskeleton. In consequence of the chronic hypoperfusion, the functionally damaged kinesin protein gives rise also to the disturbances of the trafficking of the myelin basic protein mRNAs in the oligodendrocytes. On the basis of the current knowledge on LA, this article suggests a hypothetical molecular bridge between the genetic, biochemical, and clinical processes.

ACE I/D polymorphism in Korean patients with ischemic stroke and silent brain infarction

OBJECTIVES

Angiotensin-converting enzyme (ACE) polymorphism may play a role in stroke and silent brain infarction (SBI) susceptibility, but the results among the populations studied to date have not been consistent. Thus, we investigated the association between ACE genotypes and ischemic stroke and SBI in Korean patients.

SUBJECTS AND METHODS

DNA samples from 237 stroke patients, 264 SBI patients and 234 age-matched controls were amplified using polymerase chain reaction to detect the ACE ins/del (I/D) polymorphism. Genotype was determined by the presence of a 490-bp band (I allele) or a 190-bp band (D allele) in agarose gel electrophoresis.

RESULTS

Odds ratios of the I/D and D/D genotypes and the overall (I/D + D/D) for the I/I genotype were significantly different between stroke patients and normal controls. However, there was no significant difference between patients with SBI and controls.

CONCLUSIONS

This study is the first report of a significant association between ACE polymorphism and ischemic stroke in the Asian population. Although no consistent associations have been found between ACE polymorphism and stroke in the populations studied to date, the ACE polymorphism may be a genetic determinant of ischemic stroke, at least in Korean patients.

Advances in the Genetic Basis of Ischemic Stroke

As one of the leading causes of death within both the developed and developing world, stroke is a world-wide problem. About 80% of strokes are ischemic. It is caused by multiple genetic factors, environmental factors, and interactions among these factors. There is a long list of candidate genes that have been studied for a possible association with ischemic stroke. Among the most widely investigated genes are those involved in haemostasis, inflammation, nitric oxide production, homocysteine and lipid metabolism, renin-angiotensin-aldosterone system. Combined link-age/association studies have demonstrated that genes encoding PDE4D and ALOX5AP confer risk for stroke. We review the studies of these genes which may have potential application on the early diagnosis, prevention and treatment ischemic stroke patients.

An Interactive Association of Common Sequence Variants in the Neuropeptide Y Gene With Susceptibility to Ischemic Stroke

Background and Purpose— Knowledge of the genetic architecture of ischemic stroke has been quite limited. Most significant associations of candidate genes with ischemic stroke have been difficult to replicate. This might be because the associations were not strong enough for results to be consistent, and testing a mixture of heterogeneous ischemic strokes might lead to confounded genetic associations.

Methods— A preliminary association analysis with 28 sequence variants in 18 candidate genes ( ACE, AGT, AGTR1, BDNF, CRP, F13B, LIF, MMP9, NPPA, NPY, PTGS2, SELP, SERPINE1, SREBF2, TFPI, THBD, VCAM1 , and VEGF ) revealed that NPY might be the most responsible for the susceptibility of ischemic stroke. Forty-five variants were discovered in the NPY gene by full sequencing, and 5 polymorphisms were selected based on their allele frequency and linkage disequilibrium estimates to conduct a thorough examination of their associations with ischemic stroke and its subtypes classified by TOAST. This study was conducted with 271 patients with ischemic stroke and 455 control subjects.

Results— In contrast to a slight significance for an allelic association with ischemic stroke, remarkable discrepancies between haplotype frequencies of control subjects and patients were found. Especially, TA and CC of the haplotypes composed of C4112T and A6411C in the NPY gene were associated with increased risk ( P =1.8×10 −21 , P =2.0×10 −13 ). The interchanged haplotypes, TC and CA, were protective against the diseases ( P =9.3×10 −12 , P =6.0×10 −17 ). The associations were also shown in major subtypes of ischemic stroke.

Conclusions— This remarkable haplotypic association suggested that the interaction between the 2 common sequence polymorphisms in NPY contributed to a great amount of phenotypic variability of ischemic stroke.

The combination of homozygous MTHFR 677T and angiotensin II type-1 receptor 1166C variants confers the risk of small-vessel-associated ischemic stroke

Previous studies have suggested that both angiotensin II type-1 receptor (AT1R) 1166C and methylenetetrahydrofolate reductase (MTHFR) 677T variants can have disadvantageous effects on the small-vessel circulation under certain conditions. The purpose of this study was to analyze the possible consequences of the simultaneous distribution of these two genetic variants in different types of ischemic stroke. The genetic and clinical data on 357 ischemic stroke patients and 263 control subjects were analyzed by using univariate and logistic statistical approaches. Neither the MTHFR 677T nor the AT1R 1166C genetic variant alone conferred the risk of any subtype of ischemic stroke. The combination of the homozygous MTHFR 677TT genotype and at least one AT1R 1166C allele occurred more frequently in the ischemic stroke patients (8.68%) than in the controls (4.56%, p < 0.05). Specific subclassification of the patients revealed an accumulation of this combination in small-vessel-associated ischemic stroke (12.2%, p < 0.01); multivariate logistic regression analysis of the data confirmed this association, with an odds ratio of 2.66 (95% confidence interval, 1.28-7.89; p < 0.05). These findings suggest that the combination of these two genetic factors can contribute to the development of small-vessel cerebral infarcts. Although the exact mechanism of action is not known, addition of the unfavourable effects on the endothelial function can be presumed.

Endothelial nitric oxide synthase Glu298Asp gene polymorphism is associated with hypertensive response to exercise in well-controlled hypertensive patients

PURPOSE

Hypertensive response to exercise (HRE) is known to be an adverse prognostic factor for future cardiovascular events and may be associated to endothelial dysfunction. Previous studies regarding endothelial nitric oxide synthase (eNOS) Glu298Asp polymorphism focused upon its relation to hypertension. In this study, we hypothesize that the polymorphism may be associated with inherent difference in endothelial response to exercise.

PATIENTS AND METHODS

Two hundred sixty nine patients who underwent treadmill test were enrolled in this study; 77 patients (mean age 55.8 +/- 9.4 years) had hypertensive response (peak systolic BP of > or = 210 mmHg in men and > or = 190 mmHg in women). Pulse wave velocity (PWV) was measured on 153 patients of them. The Glu298Asp exchange in exon 7 was determined by the methods of single base extension with amplifying primers and probes for TaqMan.

RESULTS

The percentages of the GG, GT and TT genotypes were 81.0, 18.6 and 0.4 %, respectively. The presence of GT or TT genotype was independently associated with prevention of HRE when controlled for age, sex, baseline systolic BP and homeostatic model assessment (HOMA) index (OR=0.35, p=0.016). Subgroup analysis showed that preventive effect for HRE of T allele was significant in females (p < 0.001) and patients without insulin resistance (p=0.009).

CONCLUSION

In our study, eNOS Glu298Asp polymorphism was significantly associated with HRE. This result suggests that the presence of T allele of the Glu298Asp polymorphism may be a favorable factor to in preventing HRE, especially in female and patients without insulin resistance.