Interleukin-6 (IL-6) rs1800796 and cyclin dependent kinase inhibitor (CDKN2A/CDKN2B) rs2383207 are associated with ischemic stroke in indigenous West African Men

Novel functional insights into ischemic stroke biology provided by the first genome-wide association study of stroke in indigenous Africans

BACKGROUND

African ancestry populations have the highest burden of stroke worldwide, yet the genetic basis of stroke in these populations is obscure. The Stroke Investigative Research and Educational Network (SIREN) is a multicenter study involving 16 sites in West Africa. We conducted the first-ever genome-wide association study (GWAS) of stroke in indigenous Africans.

METHODS

Cases were consecutively recruited consenting adults (aged > 18 years) with neuroimaging-confirmed ischemic stroke. Stroke-free controls were ascertained using a locally validated Questionnaire for Verifying Stroke-Free Status. DNA genotyping with the H3Africa array was performed, and following initial quality control, GWAS datasets were imputed into the NIH Trans-Omics for Precision Medicine (TOPMed) release2 from BioData Catalyst. Furthermore, we performed fine-mapping, trans-ethnic meta-analysis, and in silico functional characterization to identify likely causal variants with a functional interpretation.

RESULTS

We observed genome-wide significant (P-value < 5.0E-8) SNPs associations near AADACL2 and miRNA (MIR5186) genes in chromosome 3 after adjusting for hypertension, diabetes, dyslipidemia, and cardiac status in the base model as covariates. SNPs near the miRNA (MIR4458) gene in chromosome 5 were also associated with stroke (P-value < 1.0E-6). The putative genes near AADACL2, MIR5186, and MIR4458 genes were protective and novel. SNPs associations with stroke in chromosome 2 were more than 77 kb from the closest gene LINC01854 and SNPs in chromosome 7 were more than 116 kb to the closest gene LINC01446 (P-value < 1.0E-6). In addition, we observed SNPs in genes STXBP5-AS1 (chromosome 6), GALTN9 (chromosome 12), FANCA (chromosome 16), and DLGAP1 (chromosome 18) (P-value < 1.0E-6). Both genomic regions near genes AADACL2 and MIR4458 remained significant following fine mapping.

CONCLUSIONS

Our findings identify potential roles of regulatory miRNA, intergenic non-coding DNA, and intronic non-coding RNA in the biology of ischemic stroke. These findings reveal new molecular targets that promise to help close the current gaps in accurate African ancestry-based genetic stroke's risk prediction and development of new targeted interventions to prevent or treat stroke.

Identification and validation of cortisol-related hub biomarkers and the related pathogenesis of biomarkers in Ischemic Stroke

BACKGROUND

Ischemic stroke is a disease in which cerebral blood flow is blocked due to various reasons, leading to ischemia, hypoxia, softening, and even necrosis of brain tissues. The level of cortisol is related to the occurrence and progression of ischemic stroke. However, the mechanism governing their interrelationship is still unclear. The main objective of this study was to identify and understand the molecular mechanism between cortisol and IS.

METHODS

The common cortisol-related biological processes were screened by mutual verification of two data sets and the cortisol-related hub biomarkers were identified. Modular analysis of protein interaction networks was performed, and the differential pathway analysis of individual genes was conducted by GSVA and GSEA. Drug and transcription factor regulatory networks of hub genes were excavated, and the diagnostic potential of hub genes was analyzed followed by the construction of a diagnostic model.

RESULTS

By screening the two data sets by GSVA, three biological processes with common differences were obtained. After variation analysis, four cortisol-related hub biomarkers (CYP1B1, CDKN2B, MEN1, and USP8) were selected. Through the modular analysis of the protein-protein interaction network and double verification of GSVA and GSEA, a series of potential molecular mechanisms of hub genes were discovered followed by a series of drug regulatory networks and transcription factor regulatory networks. The hub biomarkers were found to have a high diagnostic value by ROC; thus, a diagnostic model with high diagnostic efficiency was constructed. The diagnostic value was mutually confirmed in the two data sets.

CONCLUSION

Four cortisol-related hub biomarkers are identified in this study, which provides new ideas for the key changes of cortisol during the occurrence of IS.

Association of single nucleotide polymorphisms of IL-6 gene with frailty in the Chinese Bai nationality

To investigate the impact of 3 single nucleotide polymorphisms (SNPs) in the interleukin-6 (IL-6) gene and their interaction on susceptibility to frailty in the elderly in rural areas of China Bai nationality. Taking the Bai people in Dali, China as the research object, and according to the frailty phenotype scale, there were 2 groups: frail and non-frail. Basic information about the study participants was gathered using a questionnaire. Clinical biochemical indices were also evaluated and the Sanger method was used to identify the sequences of the IL-6 gene loci at rs1524107, rs1800796, and rs10499563. SHEsis online software was used to analyze the linkage disequilibrium of IL-6 gene sites and the relationship between haploids and frailty. The MDR software was used to analyze the 3 sites and their interactions. Among 231 rural Bai elderly people, 63 (27.3%) were frail and 168 (72.7%) were non-frail. The SNPs of rs1524107, rs1800796, and rs10499563 in the IL-6 gene were not associated with the occurrence of frailty, nor were they associated with clinical indicators such as grip strength and gait speed. After adjusting for age and gender, there was no significant difference in the distribution of the 3 genetic models composed of the 3 SNPs between frail and non-frail populations (all P > .05). The 3 haplotypes were not associated with the occurrence of frailty, and the interaction between the 3 loci was not associated with the susceptibility to frailty. The SNP of rs1524107, rs1800796, and rs10499563 sites of IL-6 gene may not be related to frailty susceptibility in Dali Bai people. Differences in frailty mechanisms among other populations at the gene level, which are of enormous significance for the prevention and treatment of frailty, require further research with larger samples and more gene loci.

Genetic Association between Inflammatory-Related Polymorphism in STAT3, IL-1β, IL-6, TNF-α and Idiopathic Recurrent Implantation Failure

Recurrent implantation failure (RIF) is defined as a failure to achieve pregnancy after multiple embryo transfers. Implantation is closely related to inflammatory gradients, and interleukin-1beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α) play a key role in maternal and trophoblast inflammation during implantation. Signal transducer and activator of transcription 3 (STAT3) interacts with cytokines and plays a critical role in implantation through involvement in the inflammation of the embryo and placenta. Therefore, we investigated 151 RIF patients and 321 healthy controls in Korea and analyzed the association between the polymorphisms (STAT3 rs1053004, IL-1β rs16944, IL-6 rs1800796, and TNF-α rs1800629, 1800630) and RIF prevalence. In this paper, we identified that STAT3 rs1053004 (AG, adjusted odds rate [AOR] = 0.623; p = 0.027; GG, AOR = 0.513; p = 0.043; Dominant, AOR = 0.601, p = 0.011), IL-6 rs1800796 (GG, AOR = 2.472; p = 0.032; Recessive, AOR = 2.374, p = 0.037), and TNF-α rs1800629 (GA, AOR = 2.127, p = 0.010, Dominant, AOR = 2.198, p = 0.007) have a significant association with RIF prevalence. This study is the first to investigate the association of each polymorphism with RIF prevalence in Korea and to compare their effect based on their function on inflammation.

Novel inflammatory biomarkers associated with stroke severity: results from a cross-sectional stroke cohort study

BACKGROUND

Stroke is a leading cause of mortality and disability worldwide and its occurrence is expected to increase in the future. Blood biomarkers have proven their usefulness in identification and monitoring of the disease. Stroke severity is a major factor for estimation of prognosis and risk of recurrent events, but knowledge on respective blood biomarkers is still scarce. Stroke pathophysiology comprises a multitude of ischemia-induced inflammatory and immune mediated responses. Therefore, the assessment of an immune-related panel in correlation with stroke severity seems promising.

METHODS

In the present cross-sectional evaluation, a set of 92 blood biomarkers of a standardized immune panel were gathered (median 4.6 days after admission) and related to stroke severity measures, assessed at hospital admission of acute stroke patients. Multivariable logistic regression models were used to determine associations between biomarkers and modified Rankin Scale (mRS), linear regression models were used for associations with National Institute of Health Stroke Scale.

RESULTS

415 patients (mean age 69 years; 41% female) were included for biomarker analysis. C-type lectin domain family 4 member G (CLEC4G; OR = 2.89, 95% CI [1.49; 5.59], p_adj = 0.026, Cytoskeleton-associated protein 4 (CKAP4; OR = 2.38, 95% CI [1.43; 3.98], p_adj = 0.019), and Interleukin-6 (IL-6) (IL6; OR = 1.97, 95% CI [1.49; 2.62], p_adj < 0.001) were positively associated with stroke severity measured by mRS, while Lymphocyte antigen 75 (LY75; OR = 0.37, 95% CI [0.19; 0.73], p_adj = 0.049) and Integrin alpha-11 (ITGA11 OR = 0.24, 95% CI [0.14, 0.40] p_adj < 0.001) were inversely associated. When investigating the relationships with the NIHSS, IL-6 (β = 0.23, 95% CI [0.12, 0.33] p_adj = 0.001) and ITGA11 (β =  - 0.60, 95% CI [- 0.83, - 0.37] p_adj < 0.001) were significantly associated.

CONCLUSIONS

Higher relative concentrations of plasma CLEC4G, CKAP4, and IL-6 were associated with higher stroke severity, whereas LY75 and ITGA11 showed an inverse association. Future research might show a possible use as therapeutic targets and application in individual risk assessments.

Transcriptomic analysis reveals the potential biological mechanism of AIS and lung adenocarcinoma

Introduction

Acute ischemic stroke (AIS) and lung adenocarcinoma (LUAD) are associated with some of the highest morbidity and mortality rates worldwide. Despite reports on their strong correlation, the causal relationship is not fully understood. The study aimed to identify and annotate the biological functions of hub genes with clinical diagnostic efficacy in AIS and LUAD.

Methods

Transcriptome and single-cell datasets were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). We identified the differentially expressed genes (DEGs) upregulated in AIS and LUAD and found 372 genes intersecting both datasets. Hub genes were identified using protein-protein interaction (PPI) networks, and the diagnostic and prognostic utility of these hub genes was then investigated using receiver operating characteristic (ROC) curves, survival analysis, and univariable Cox proportional hazard regression. Single-cell analysis was used to detect whether the hub genes were expressed in tumor epithelial cells. The immune microenvironment of AIS and LUAD was assessed using the CIBERSORT algorithm. The protein expression of these hub genes was tracked using the Human Protein Atlas (HPA). We calculated the number of positive cells using the digital pathology software QuPath. Finally, we performed molecular docking after using the Enrichr database to predict possible medicines.

Results

We identified the molecular mechanisms underlying hub genes in AIS and LUAD and found that CCNA2, CCNB1, CDKN2A, and CDK1 were highly expressed in AIS and LUAD tissue samples compared to controls. The hub genes were mainly involved in the following pathways: the cell cycle, cellular senescence, and the HIF-1 signaling pathway. Using immunohistochemical slices from the HPA database, we confirmed that these hub genes have a high diagnostic capability for AIS and LUAD. Further, their high expression is associated with poor prognosis. Finally, curcumin was tested as a potential medication using molecular docking modeling.

Discussion

Our findings suggest that the hub genes we found in this study contribute to the development and progression of AIS and LUAD by altering the cellular senescence pathway. Thus, they may be promising markers for diagnosis and prognosis.

Increased Frequencies of the ‒174G and ‒572C IL6 Alleles in Populations of Indigenous Peoples of Siberia Compared to Russians

Abstract-The study of immune response and inflammation gene polymorphisms in a genogeographic context is relevant in the study of human populations. Here, in the indigenous populations of Siberia the frequencies of polymorphic variants ‒174G/C (rs1800795) and ‒572C/G (rs1800796) of the IL6 gene encoding the proinflammatory cytokine IL-6 were determined. For the first time, it was shown that the frequencies of the ‒174G and ‒572C alleles, which determine increased inflammatory response and are also associated with several diseases were statistically significantly higher in ethnic groups of Buryats, Teleuts, Yakuts, Dolgans and Tuvinians than in Russians living in Siberia. These values were in the intermediate position between those in the European and East-Asian groups. We hypothesize an adaptive role of these IL6 genetic variants in human settlement from Africa to the Eurasian continent. However, due to the departure from the traditional way of life and the increasing anthropogenic environmental pollution, the risk of diseases whose pathogenesis is based on inflammation in indigenous Siberian populations is likely increased.

Polymorphism rs2383207 of CDKN2B-AS and Susceptibility to Atherosclerosis: A Mini Review

We conducted this meta-analysis to estimate associations between CDKN2B antisense (CDKN2B-AS) rs2383207 polymorphism and susceptibility to atherosclerosis. A systematic literature research of Google Scholar and PubMed was performed to identify eligible studies. Overall, eight studies were included for meta-analyses. The association was assessed by statistical odds' ratio (OR) with 95% confidence interval (CI). RevMan software (Cochrane Collaboration, 5.3. Copenhagen) was used for the meta-analysis. Pooled overall analyses showed that rs2383207 polymorphism was associated with the risk of atherosclerosis in the whole population. Additional analyses by ethnicity revealed that rs2383207 polymorphism was associated with susceptibility to atherosclerosis in Asians and Caucasians. Our results suggest that rs2383207, might serve as genetic biomarkers of atherosclerosis. Further, studies will be required to confirm the observed association.

Association of Single-Nucleotide Polymorphisms of rs2383206, rs2383207, and rs10757278 With Stroke Risk in the Chinese Population: A Meta-analysis

Several studies have reported that chromosome 9p21 is significantly associated with ischemic stroke (IS) risk, with the G allele associated with increased risk. However, controversial results have been reported in the literature. We systematically assessed the relationship between stroke and three 9p21 loci (rs2383206, rs2383207, and rs10757278) in this meta-analysis. First, we searched the PubMed and Embase databases for relevant studies. We then calculated odds ratios using the chi-squared test. The evaluation of experimental data was performed using bias tests and sensitivity analyses. We analyzed data from 16 studies involving 18,584 individuals of Chinese ancestry, including 14,033 cases and 14,656 controls. Our results indicated that chromosome 9p21 is significantly associated with IS (odds ratio: 1.15, 95% confidence interval: 1.1–1.20, p < 0.0001). Because the three single-nucleotide polymorphisms (rs2383206, rs2383207, and 10757278) have a linkage disequilibrium relationship, all three may increase the risk of IS.

Non-Communicable Neurological Disorders and Neuroinflammation

Traumatic brain injury, stroke, and neurodegenerative diseases represent a major cause of morbidity and mortality in Africa, as in the rest of the world. Traumatic brain and spinal cord injuries specifically represent a leading cause of disability in the younger population. Stroke and neurodegenerative disorders predominantly target the elderly and are a major concern in Africa, since their rate of increase among the ageing is the fastest in the world. Neuroimmunology is usually not associated with non-communicable neurological disorders, as the role of neuroinflammation is not often considered when evaluating their cause and pathogenesis. However, substantial evidence indicates that neuroinflammation is extremely relevant in determining the consequences of non-communicable neurological disorders, both for its protective abilities as well as for its destructive capacity. We review here current knowledge on the contribution of neuroinflammation and neuroimmunology to the pathogenesis of traumatic injuries, stroke and neurodegenerative diseases, with a particular focus on problems that are already a major issue in Africa, like traumatic brain injury, and on emerging disorders such as dementias.

Genetic association of ANRIL with susceptibility to Ischemic stroke: A comprehensive meta-analysis

Background

Ischemic stroke (IS) is a complex polygenic disease with a strong genetic background. The relationship between the ANRIL (antisense non-coding RNA in the INK4 locus) in chromosome 9p21 region and IS has been reported across populations worldwide; however, these studies have yielded inconsistent results. The aim of this study is to clarify the types of single-nucleotide polymorphisms on the ANRIL locus associated with susceptibility to IS using meta-analysis and comprehensively assess the strength of the association.

Methods

Relevant studies were identified by comprehensive and systematic literature searches. The quality of each study was assessed using the Newcastle-Ottawa Scale. Allele and genotype frequencies were extracted from each of the included studies. Odds ratios with corresponding 95% confidence intervals of combined analyses were calculated under three genetic models (allele frequency comparison, dominant model, and recessive model) using a random-effects or fixed-effects model. Heterogeneity was tested using the chi-square test based on the Cochran Q statistic and I2 metric, and subgroup analyses and a meta-regression model were used to explore sources of heterogeneity. The correction for multiple testing used the false discovery rate method proposed by Benjamini and Hochberg. The assessment of publication bias employed funnel plots and Egger’s test.

Results

We identified 25 studies (15 SNPs, involving a total of 11,527 cases and 12,216 controls maximum) and performed a meta-analysis. Eight SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1333049, rs1537378, rs4977574, and rs1004638) in ANRIL were significantly associated with IS risk. Six of these SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1537378, and rs4977574) had a significant relationship to the large artery atherosclerosis subtype of IS. Two SNPs (rs2383206 and rs4977574) were associated with IS mainly in Asians, and three SNPs (rs10757274, rs1333040, and rs1333049) were associated with susceptibility to IS mainly in Caucasians. Sensitivity analyses confirmed the reliability of the original results. Ethnicity and individual studies may be the main sources of heterogeneity in ANRIL.

Conclusions

Our results suggest that some single-nucleotide polymorphisms on the ANRIL locus may be associated with IS risk. Future studies with larger sample numbers are necessary to confirm this result. Additional functional analyses of causal effects of these polymorphisms on IS subtypes are also essential.

The 2021 William Feinberg Award Lecture Seeking Glocal Solutions to Cerebrovascular Health Inequities

Global and local (“glocal”) disparities in stroke incidence, prevalence, care, and mortality are persistent, pervasive, and progressive. In particular, the disproportionate burden of stroke in people of African ancestry compared to most other racial/ethnic groups around the world has been long standing, is expected to worsen, and so far, has defied solution, largely because conventional risk factors likely account for less than half of the Black versus White disparity in stroke outcomes. While hypotheses such as a differential impact or inadequate evaluation of traditional risk factors by race have been suggested as potentially key factors contributing to lingering racial/ethnic stroke disparities, relatively understudied novel risk factors such as psychosocial stress, environmental pollution, and inflammation; and influences of the social determinants of health are gaining the most attention (and momentum). Moreover, it is increasingly recognized that while there is a lot still to understand, there needs to be a major shift from incessantly studying the problem, to developing interventions to resolve it. Resolution will likely require targeting multilevel factors, considering contemporaneous cross-national and cross-continental data collection, creating scalable care delivery models, jointly addressing care quality and community drivers of stroke occurrence, incorporating policy makers in planning/dissemination of successful interventions, and investing in robust transdisciplinary research training programs that address the interrelated issues of health equity and workforce diversity, and regional capacity building. To this end, our international multidisciplinary team has been involved in conducting several epidemiological studies and clinical trials in the area of stroke disparities, as well as executing career enhancing research training programs in the United States and Africa. This award lecture paper shares some of the lessons we have learnt from previous studies, presents objectives/design of ongoing initiatives, and discusses plans for the future.

Genetic and Genomic Epidemiology of Stroke in People of African Ancestry

Stroke is one of the leading causes of disability and death worldwide and places a significant burden on healthcare systems. There are significant racial/ethnic differences in the incidence, subtype, and prognosis of stroke, between people of European and African ancestry, of which only about 50% can be explained by traditional stroke risk facts. However, only a small number of genetic studies include individuals of African descent, leaving many gaps in our understanding of stroke genetics among this population. This review article highlights the need for and significance of including African-ancestry individuals in stroke genetic studies and points to the efforts that have been made towards this direction. Additionally, we discuss the caveats, opportunities, and next steps in African stroke genetics-a field still in its infancy but with great potential for expanding our understanding of stroke biology and for developing new therapeutic strategies.

Single nucleotide polymorphisms in the ANGPTL4 gene and the SNP-SNP interactions on the risk of atherosclerotic Ischaemic stroke

Objectives

The purpose of this study was to investigate the impact of single nucleotide polymorphisms (SNPs) in the ANGPTL4 gene and the SNP–SNP interactions on atherosclerotic ischemic stroke (IS) risk.

Patients and methods

A case-control study was conducted. A total of 360 patients with atherosclerotic IS and 342 controls between December 2018 and December 2019 from Longyan First Hospital affiliated to Fujian Medical University were included. A logistic regression model was used to examine the association between SNPs and atherosclerotic IS risk. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. Generalized multifactor dimensionality reduction was employed to analyze the SNP-SNP interaction.

Results

Logistic regression analysis showed that atherosclerotic IS risk was significantly lower in carriers with the rs11672433-T allele than those with the CC genotype (CT+ TT vs. CC); adjusted OR, 0.005; 95% CI, 0.02–0.11. We found a significant 2-locus model (P = 0.0010) involving rs11672433 and rs4076317; the cross-validation consistency of this model was 10 of 10, and the testing accuracy was 57.96%. Participants with the CT or TT of rs11672433 and CC of rs4076317 genotype have the lowest atherosclerotic IS risk, compared to subjects with CC of rs11672433 and the CC of rs4076317 genotype, OR (95%CI) was 0.06(0.02–0.22), after covariates adjustment for gender, age, smoking and alcohol status, hypertension, Diabetes mellitus, TG, TC, HDL-C, LDL-C, Uric acid.

Conclusions

We found that rs11672433 was associated with decreased atherosclerotic IS risk; we also found that gene–gene interaction between rs11672433 and rs4076317 was associated with decreased atherosclerotic IS risk.

Stroke in Africa: profile, progress, prospects and priorities

Stroke is a leading cause of disability, dementia and death worldwide. Approximately 70% of deaths from stroke and 87% of stroke-related disability occur in low-income and middle-income countries. At the turn of the century, the most common diseases in Africa were communicable diseases, whereas non-communicable diseases, including stroke, were considered rare, particularly in sub-Saharan Africa. However, evidence indicates that, today, Africa could have up to 2-3-fold greater rates of stroke incidence and higher stroke prevalence than western Europe and the USA. In Africa, data published within the past decade show that stroke has an annual incidence rate of up to 316 per 100,000, a prevalence of up to 1,460 per 100,000 and a 3-year fatality rate greater than 80%. Moreover, many Africans have a stroke within the fourth to sixth decades of life, with serious implications for the individual, their family and society. This age profile is particularly important as strokes in younger people tend to result in a greater loss of self-worth and socioeconomic productivity than in older individuals. Emerging insights from research into stroke epidemiology, genetics, prevention, care and outcomes offer great prospects for tackling the growing burden of stroke on the continent. In this article, we review the unique profile of stroke in Africa and summarize current knowledge on stroke epidemiology, genetics, prevention, acute care, rehabilitation, outcomes, cost of care and awareness. We also discuss knowledge gaps, emerging priorities and future directions of stroke medicine for the more than 1 billion people who live in Africa.

Antecedent febrile illness and occurrence of stroke in West Africa: The SIREN study

BACKGROUND

Acute infections have been posited as potential precipitants or triggers of the occurrence of stroke among adults with traditional vascular risk factors. We evaluated associations between stroke occurrence and reported febrile illness within 4 weeks (potential antecedent infections) among West Africans.

METHODS

The Stroke Investigative Research and Educational Network (SIREN) is a multicenter, case-control study involving 15 sites in Ghana and Nigeria. Cases include adults aged ≥18 years with radiologically confirmed strokes. Controls were stroke-free adults matched with cased by age, gender and ethnicity. Detailed evaluations for vascular, lifestyle and psychosocial factors were performed. Participants were asked for evidence of any febrile illness within the past 4 weeks. We used conditional logistic regression to estimate adjusted odds ratios (aOR) with 95% Confidence Interval.

RESULTS

Among 3588 stroke cases recruited in Ghana and Nigeria between August 2014 and July 2018, 363 cases (10.1%) reported having a febrile illness within the 4 weeks prior to stroke occurrence. Having an antecedent infection was associated with stroke occurrence with an unadjusted OR of 1.19 (1.00-1.51) but aOR of 0.83 (0.59-1.17) upon adjusting for traditional vascular risk factors. Stress, aOR of 4.69 (2.59-8.50) and consumption of green vegetables 2.27 (1.35-2.85) were associated with antecedent febrile illness.

CONCLUSION

1 in 10 stroke cases reported antecedent history of febrile illness prior to occurrence of stroke but no independent association was observed in this study. Infectious exposures may be important triggers of cardiovascular events requiring further exploratory studies to better understand the role of this emerging risk factor.

Vascular-brain Injury Progression after Stroke (VIPS) study: concept for understanding racial and geographic determinants of cognitive decline after stroke

Cognitive impairment and dementia (CID) are major public health problems with substantial personal, social, and financial burdens. African Americans are at a heightened risk for Vascular Cognitive Impairment (VCI) compared to European Americans. Recent lines of evidence also suggest a high burden of Post-stroke VCI among indigenous Africans. A better understanding of the cause(s) of the racial disparity in CID, specifically VCI, is needed in order to develop strategies to reduce it. We propose and discuss the conceptual framework for a unique tri-population, trans-continental study titled The Vascular brain Injury Progression after Stroke (VIPS) study. The overarching objective of the VIPS Study will be to explore the interplay of multiple factors (racial, geographical, vascular, lifestyle, nutritional, psychosocial and inflammatory) influencing the level and trajectory of post-stroke cognitive outcomes and examine whether differences between indigenous Africans, African Americans and European Americans exist. We hypothesize that differences which might be due to racial factors will be observed in African Americans versus European Americans as well as Indigenous Africans versus European Americans but not in African Americans versus Indigenous Americans; differences due to geographical factors will be observed in Indigenous Americans versus African Americans and Indigenous Africans versus European Americans but not in African Americans versus European Americans. This overarching objective could be accomplished by building upon existing National Institutes of Health investments in the REasons for Geographical And Racial Differences in Stroke (REGARDS) study (based in the United States of America) and the Stroke Investigative Research and educational Network (SIREN) study (based in Sub-Saharan Africa).

Association study of genetic variations of inflammatory biomarkers with susceptibility and severity of obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) increases health risks of cardiovascular disease and stroke. Both genetic factors and environmental exposures contribute to the occurrence of OSA. The purpose of this study was to determine the role of four functional inflammatory single nucleotide polymorphisms (SNPs) (VWF rs1063856, IL-6 rs1800796, TNF rs1800629, and CRP rs2794521) in the susceptibility and severity of OSA.

METHODS

A case-control study of OSA among Chinese population was conducted. Genotyping was performed using ABI TaqMan SNP genotyping technique.

RESULTS

We found VWF rs1063856 (OR = 1.50, 95% CIs = 1.10-2.04; p = 0.010), IL-6 rs1800796 (OR = 1.32, 95% CIs = 1.11-1.56; p = 0.002), TNF rs1800629 (OR = 1.44, 95% CIs = 1.13-1.83; p = 0.003), and CRP rs2794521 (OR = 1.27, 95% CIs = 1.04-1.55; p = 0.021) were all significantly associated with increased susceptibility of OSA, while VWF rs1063856 (OR = 1.75, 95% CIs = 1.18-2.62; p = 0.006), IL-6 rs1800796 (OR = 1.39, 95% CIs = 1.10-1.76; p = 0.006) were associated with the severity of OSA.

CONCLUSIONS

Our study indicated that functional variants of inflammatory biomarkers could cause the occurrence of OSA and influence the severity of OSA. These findings further support that inflammatory cytokines were closely related to the occurrence and development of OSA.

Interleukin 6 (rs1800795) gene polymorphism is associated with cardiovascular diseases: a meta-analysis of 74 studies with 86,229 subjects

Cardiovascular diseases (CVD) are group of complex and multifactorial pathologies, in which interleukin-6 (IL-6) gene polymorphisms have been associated with several components of the CVD. Thus, in this study, we thoroughly reviewed and meta-analyzed evidence on the association between the IL-6 (rs1800795) gene polymorphism and CVD. We systematically searched in the PubMed, Web of Sciences, and Scopus databases. The analyses were performed using five study groups based on (1) a combined pool of the overall populations, (2) the country of birth, (3) the continent of birth, (4) the diagnosis and (5) both location (country or continent) and diagnosis. The analysis included the allelic, homozygote, heterozygote, dominant and recessive models. The meta-analysis showed that -174G>C (rs1800795) is a risk factor for CVD (allelic: OR=1.06, CI 95%=1.02-1.10. Z p value <0.0001; homozygous: OR=1.11, CI 95%=1.03-1.19, Z p value= 0.002; heterozygous: OR=1.08, CI 95%=1.03-1.21, Z p value= 0.003; dominant: OR= 1.12, CI 95%= 1.07-1.18, Z p value= 0.001) and that this risk increases in the Chinese population. Additionally, we found that carriers of the C allele of 174G>C (rs1800795) polymorphism have an increase in the risk of coronary artery disease under the hereditary models assessed in the study. Using robust data, we found that IL-6 (rs1800795) -174G>C gene polymorphism is associated with CVD risk.

Bioinformatics Analysis of Gene Expression Profiles of Sex Differences in Ischemic Stroke

Ischemic stroke (IS) is a complex disease with sex differences in epidemiology, presentations, and outcomes. However, the sex-specific mechanism underlying IS remains unclear. The purpose of this study was to identify key genes contributing to biological differences between sexes. First, we downloaded the gene expression data of GSE22255 from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were identified using R software and related packages. Second, DEGs were separately analyzed by Gene Ontology enrichment and pathways analyses. Third, protein-protein interaction (PPI) network was constructed to further investigate the interactions of DEGs. A total of 123 DEGs were identified between sexes, including 8 upregulated and 115 downregulated genes. In the PPI network, ten key genes were identified, including IL1α, IL1β, IL6, IL8, CXCL1, CXCL2, CXCL20, CCL4, ICAM1, and PTGS2. Functional enrichment analysis revealed that these genes were mainly enriched in biological processes of immune response and apoptotic process, also in pathways of TNF and NOD-like receptor signaling. In conclusion, the above ten genes may have a protective effect on IS females through their direct or indirect involvement in biological processes of immune response and apoptotic process, as well as in TNF and NOD-like receptor signaling pathways. The results of this study may help to gain new insights into the sex-specific mechanisms underlying IS females and may suggest potential therapeutic targets for disease treatment.

Association and interaction of genetic variants with occurrence of ischemic stroke among Brazilian patients

Ischemic Stroke (IS) is a severe and complex disorder of high morbidity and mortality rates associated with clinical, environmental, and genetic predisposing factors. Despite previous studies have associated genetic variants to stroke, inconsistent results from different populations pointed to the genetic heterogeneity for IS. Therefore, we may hypothesize that an interaction effect among genetic variants could contribute to IS occurrence rather than genetic variants independently. In this context, we investigated the association and interaction between genetic variants and large-artery atherosclerosis IS (LAAS-IS) and cardioembolic IS (CE-IS). We genotyped 435 patients (195 LAAS-IS; 240 CE-IS) and 535 controls from a population of Joinville, Santa Catarina, Brazil. Association and interaction analysis were performed by chi-square test and Multifactor-dimensionality Reduction test. We found an association between rs2383207*A allele, nearby CDKN2B-AS1, and LAAS-IS [OR 2.35 (95% CI = 1.79-3.08); p = 4.66 × 10^-10]. We found an interaction among rs2910829, rs966221 and rs152312, with an accuracy of 0.62 (p = 4.3 × 10^-5) demonstrating the interaction effect among variants from different genes can contribute to CE-IS risk. Further prediction analysis confirmed that clinical information, such as hypertension and dyslipidemia, presented high accuracy to predict LAAS-IS (86.47%) and CE-IS (90.47%); however, the inclusion of genetic variant information did not increase the accuracy.

Knowledge, attitudes and practices of West Africans on genetic studies of stroke: Evidence from the SIREN Study

BACKGROUND

It is crucial to assess genomic literacy related to stroke among Africans in preparation for the ethical, legal and societal implications of the genetic revolution which has begun in Africa.

OBJECTIVE

To assess the knowledge, attitudes and practices (KAP) of West Africans about stroke genetic studies.

METHODS

A comparative cross-sectional study was conducted among stroke patients and stroke-free controls recruited across 15 sites in Ghana and Nigeria. Participants' knowledge of heritability of stroke, willingness to undergo genetic testing and perception of the potential benefits of stroke genetic research were assessed using interviewer-administered questionnaire. Descriptive, frequency distribution and multiple regression analyses were performed.

RESULTS

Only 49% of 2029 stroke patients and 57% of 2603 stroke-free individuals knew that stroke was a heritable disorder. Among those who knew, 90% were willing to undergo genetic testing. Knowledge of stroke heritability was associated with having at least post-secondary education (OR 1.51, 1.25-1.81) and a family history of stroke (OR 1.20, 1.03-1.39) while Islamic religion (OR=0.82, CI: 0.72-0.94), being currently unmarried (OR = 0.81, CI: 0.70-0.92), and alcohol use (OR = 0.78, CI: 0.67-0.91) were associated with lower odds of awareness of stroke as a heritable disorder. Willingness to undergo genetic testing for stroke was associated with having a family history of stroke (OR 1.34, 1.03-1.74) but inversely associated with a medical history of high blood pressure (OR = 0.79, 0.65-0.96).

CONCLUSION

To further improve knowledge of stroke heritability and willingness to embrace genetic testing for stroke, individuals with less formal education, history of high blood pressure and no family history of stroke require targeted interventions.

Evaluation of the role of CDKN2B gene in type 2 diabetes mellitus and hypertension in ethnic Saudi Arabs

Background

Coronary heart disease (CAD) is a multiple with several contributory risk traits, including type 2 diabetes and hypertension, which may share common genetic risk variants with the disease. Genome-wide association studies (GWASs) have yielded a wealth of information suggesting that CAD, the extent of contributory variants may differ according to genetic locus. The present study aimed at verifying whether the cyclin-dependent kinase 4 inhibitor B (CDKN2B) genomic region strongly associated with coronary artery disease (CAD)/myocardial infarction (MI) may also constitute risk for its risk factors type 2 diabetes mellitus (T2DM) and hypertension (HTN) in ethnic Saudi Arabs.

Methodology

We genotyped eight CDKN2B SNPs for cardiovascular risk in a total of 4650 Saudi Arabs, (3049 male and 1601 female) by Taqman assay. Of these individuals, 3732 had primary hypertension and 2576 had type 2 diabetes mellitus.

Results

Out of the eight studied SNPs, two, rs10757274_A [0.915 (0.840-1.00); p = 0.042], rs1333045_T [0.92(0.84-1.00); p = 0.048] were initially associated with type 2 diabetes but lost the association after multivariate adjustments for CAD, hypertension and MI, while rs10757274_A showed borderline association with hypertension.

Conclusions

Our finding does not support the notion of a critical role for the CDKN2B gene locus as a HTN or T2DM cardiovascular risk in ethnic Arabs. The study also demonstrates the importance of replication studies in ascertaining the role of a genomic sequence in disease.

Stroke Among Young West Africans: Evidence From the SIREN (Stroke Investigative Research and Educational Network) Large Multisite Case-Control Study

BACKGROUND AND PURPOSE

Stroke in lower and middle-income countries affects a young and productive age group. Data on factors associated with stroke in the young are sorely lacking from lower and middle-income countries. Our objective is to characterize the nature of stroke and its risk factors among young West Africans aged <50 years old.

METHODS

The SIREN (Stroke Investigative Research and Educational Network) is a multicenter, case-control study involving 15 sites in Nigeria and Ghana. Cases included adults aged ≥18 years with computed tomography/magnetic resonance imaging-confirmed stroke. Controls were age-and gender-matched stroke-free adults recruited from the communities in catchment areas of cases. Comprehensive evaluation for vascular, lifestyle, and psychosocial factors was performed. We used conditional logistic regression to estimate odds ratios and population attributable risks with 95% confidence intervals.

RESULTS

Five hundred fifteen (24.3%) out of 2118 cases enrolled were <50 years old. Among subjects <50 years old, hemorrhagic stroke proportion was 270 (52.5%) versus 245 (47.5%) for ischemic strokes. Etiologic subtypes of ischemic strokes included large artery atherosclerosis (40.0%), small vessel disease (28.6%), cardioembolism (11.0%), and undetermined (20.4%). Hypertension (91.7%), structural lesions (3.4%), and others (4.9%) were causally associated with hemorrhagic stroke. Six topmost modifiable factors associated with stroke in descending order of population attributable risk (95% confidence interval) were hypertension: 88.7% (82.5%-94.8%), dyslipidemia: 48.2% (30.6%-65.9%), diabetes mellitus: 22.6% (18.7%-26.5%), low green vegetable consumption: 18.2% (-6.8%-43.2%), stress: 14.5% (4.9%-24.1%), and cardiac disease: 8.4% (5.8%-11.1%).

CONCLUSIONS

The high and rising burden of stroke among young Africans should be curtailed via aggressive, population-wide vascular risk factor control.

H3Africa: current perspectives

Precision medicine is being enabled in high-income countries by the growing availability of health data, increasing knowledge of the genetic determinants of disease and variation in response to treatment (pharmacogenomics), and the decreasing costs of data generation, which promote routine application of genomic technologies in the health sector. However, there is uncertainty about the feasibility of applying precision medicine approaches in low- and middle-income countries, due to the lack of population-specific knowledge, skills, and resources. The Human Heredity and Health in Africa (H3Africa) initiative was established to drive new research into the genetic and environmental basis for human diseases of relevance to Africans as well as to build capacity for genomic research on the continent. Precision medicine requires this capacity, in addition to reference data on local populations, and skills to analyze and interpret genomic data from the bedside. The H3Africa consortium is collectively processing samples and data for over 70,000 participants across the continent, accompanied in most cases by rich clinical information on a variety of non-communicable and infectious diseases. These projects are increasingly providing novel insights into the genetic basis of diseases in indigenous populations, insights that have the potential to drive the development of new diagnostics and treatments. The consortium has also invested significant resources into establishing high-quality biorepositories in Africa, a bioinformatic network, and a strong training program that has developed skills in genomic data analysis and interpretation among bioinformaticians, wet-lab researchers, and health-care professionals. Here, we describe the current perspectives of the H3Africa consortium and how it can contribute to making precision medicine in Africa a reality.

APOL1, CDKN2A/CDKN2B, and HDAC9 polymorphisms and small vessel ischemic stroke

OBJECTIVE

Worldwide, the highest frequencies of APOL1-associated kidney variants are found in indigenous West Africans among whom small vessel disease (SVD) ischemic stroke is the most common stroke phenotype. The objective of this study was to investigate the association and effect sizes of 23 selected SNPs in 14 genes of relevance, including the APOL1 G1 variants, with the occurrence of SVD ischemic stroke among indigenous West African participants in the Stroke Investigative Research and Education Network (SIREN) Study.

MATERIALS AND METHODS

Cases were consecutively recruited consenting adults (aged 18 years or older) with neuroimaging-confirmed first clinical stroke. Stroke-free controls were ascertained using a locally validated version of the Questionnaire for Verifying Stroke-Free Status (QVSFS). Logistic regression models adjusting for known vascular risk factors were fitted to assess the associations of the 23 SNPs in rigorously phenotyped cases (N = 154) of SVD ischemic stroke and stroke-free (N = 483) controls.

RESULTS

Apolipoprotein L1 (APOL1) rs73885319 (OR = 1.52; CI: 1.09-2.13, P-value = .013), rs2383207 in CDKN2A/CDKN2B (OR = 3.08; CI: 1.15-8.26, P -value = .026) and rs2107595 (OR = 1.70; CI: 1.12-2.60, P-value = .014) and rs28688791 (OR = 1.52; CI: 1.03-2.26, P-value = .036) in HDAC9 gene were associated with SVD stroke at 0.05 significance level. Polymorphisms in other genes did not show significant associations.

CONCLUSION

This is the first report of a specific association of APOL1 with a stroke subtype. Further research is needed to confirm these initial findings and deepen understanding of the genetics of stroke in people of African ancestry with possible implications for other ancestries as all humans originated from Africa.

Advancing stroke genomic research in the age of Trans-Omics big data science: Emerging priorities and opportunities

BACKGROUND

We systematically reviewed the genetic variants associated with stroke in genome-wide association studies (GWAS) and examined the emerging priorities and opportunities for rapidly advancing stroke research in the era of Trans-Omics science.

METHODS

Using the PRISMA guideline, we searched PubMed and NHGRI- EBI GWAS catalog for stroke studies from 2007 till May 2017.

RESULTS

We included 31 studies. The major challenge is that the few validated variants could not account for the full genetic risk of stroke and have not been translated for clinical use. None of the studies included continental Africans. Genomic study of stroke among Africans presents a unique opportunity for the discovery, validation, functional annotation, Trans-Omics study and translation of genomic determinants of stroke with implications for global populations. This is because all humans originated from Africa, a continent with a unique genomic architecture and a distinctive epidemiology of stroke; as well as substantially higher heritability and resolution of fine mapping of stroke genes.

CONCLUSION

Understanding the genomic determinants of stroke and the corresponding molecular mechanisms will revolutionize the development of a new set of precise biomarkers for stroke prediction, diagnosis and prognostic estimates as well as personalized interventions for reducing the global burden of stroke.