Interleukin-6 −174G/C Polymorphism and Ischemic Stroke

Telomere length as a biomarker for cerebrovascular diseases: current evidence

Cerebrovascular disease (CVD) includes a range of conditions affecting the brain's blood vessels, which can result in reduced blood flow to brain tissue. The most common manifestation of CVD is stroke, the second leading cause of death and the third leading cause of disability worldwide. Major risk factors for CVD encompass gender, age, smoking, hypertension, diabetes, physical inactivity, obesity, alcohol consumption, and metabolic syndrome. Research suggests a link between telomere length and an increased risk of CVD, particularly in ischemic stroke cases. This review highlights key findings on the relationship between telomere length and CVD, underscoring its clinical importance. The analysis utilizes scientific literature from PubMed, Scopus, and SciELO up to 2024. Results show that shorter telomere length is associated with various types of CVD, including stroke, ischemic stroke, hemorrhagic stroke, and cardioembolic stroke. Some studies propose that telomere length measurement could be a valuable biomarker for CVD, potentially improving prevention, diagnosis, and management strategies.

Dynamic changes in Beclin-1, LC3B, and p62 in aldose reductase-knockout mice at different time points after ischemic stroke

Ischemic stroke is a brain injury caused by cerebral blood circulation disorders and is closely related to oxidative stress. Aldose reductase (AR) is a critical enzyme involved in oxidative stress. Autophagy has previously been found to play a key role in cerebral ischemia‒reperfusion injury. However, it is still unclear how autophagy molecules change after cerebral ischemia‒reperfusion injury in AR knockout mice (AR-/-). A transient middle cerebral artery occlusion (tMCAO) model was generated in AR-/- mice, and the neurological deficit scores of the mice were observed and recorded on Days 1, 3 and 5 after tMCAO. Neuronal damage in the ischemic penumbra was observed by TTC, HE, and Nissl staining. The expression of the autophagy-related molecules Beclin-1, LC3II/I, and P62 as well as that of molecules related to inflammation, oxidative stress, and neurological damage was detected by RT‒qPCR, western blotting, and immunofluorescence. Autophagosomes were observed using a transmission electron microscope. Cerebral ischemia‒reperfusion injury caused neurological deficits and ischemic infarction in tMCAO mice (P < 0.01). Beclin-1, Bcl2/Bax, SOD, GSH-px, P62, PSD95, and TOM20 levels decreased (P < 0.05), while IL-6, LC3II/I, and GFAP levels increased (P < 0.01) in the AR-/- tMCAO-1d group and the AR-/- tMCAO-3d group, compared to those in the sham group. Beclin-1, Bcl2/Bax, NOX4, GSH-px, P62, and PSD95 levels increased (P < 0.01), while IL-6, LC3II/I, and GFAP levels decreased (P < 0.01) in the AR-/- tMCAO-5d group compared to those in the AR-/- tMCAO-1d group. Autophagosome formation was observed in tMCAO mice. In summary, the changes in autophagy proteins in the brain tissue of the AR-/- mice after tMCAO were more obvious on Days 1 and 3 after tMCAO. The expression of Beclin-1 and P62 decreased, and the expression of LC3B increased after cerebral ischemia‒reperfusion injury in AR-/- mouse brain tissue.

Genetics of ischemic stroke functional outcome

Ischemic stroke, which accounts for 87% of cerebrovascular accidents, is responsible for massive global burden both in terms of economic cost and personal hardship. Many stroke survivors face long-term disability-a phenotype associated with an increasing number of genetic variants. While clinical variables such as stroke severity greatly impact recovery, genetic polymorphisms linked to functional outcome may offer physicians a unique opportunity to deliver personalized care based on their patient's genetic makeup, leading to improved outcomes. A comprehensive catalogue of the variants at play is required for such an approach. In this review, we compile and describe the polymorphisms associated with outcome scores such as modified Rankin Scale and Barthel Index. Our search identified 74 known genetic polymorphisms spread across 48 features associated with various poststroke disability metrics. The known variants span diverse biological systems and are related to inflammation, vascular homeostasis, growth factors, metabolism, the p53 regulatory pathway, and mitochondrial variation. Understanding how these variants influence functional outcome may be helpful in maximizing poststroke recovery.

Immune response treated with bone marrow mesenchymal stromal cells after stroke

Stroke is a leading cause of death and long-term disability worldwide. Tissue plasminogen activator (tPA) is an effective treatment for ischemic stroke. However, only a small part of patients could benefit from it. Therefore, finding a new treatment is necessary. Bone marrow mesenchymal stromal cells (BMSCs) provide a novel strategy for stroke patients. Now, many patients take stem cells to treat stroke. However, the researches of the precise inflammatory mechanism of cell replacement treatment are still rare. In this review, we summarize the immune response of BMSCs treated to stroke and may provide a new perspective for stem cell therapy.

Inflammatory Cytokines and Risk of Ischemic Stroke: A Mendelian Randomization Study

Background: Observational studies have revealed the association between some inflammatory cytokines and the occurrence of ischemic stroke, but the causal relationships remain unclear.

Methods: We conducted a two-sample Mendelian randomization (MR) analysis to assess the causal effects of thirty inflammatory cytokines and the risk of ischemic stroke. For exposure data, we collected genetic variants associated with inflammatory cytokines as instrumental variables (IVs) from a genome-wide association study (GWAS) meta-analysis from Finland (sample size up to 8,293). For the outcome data, we collected summary data of ischemic stroke from a large-scale GWAS meta-analysis involved 17 studies (34,217 cases and 406,111 controls). We further performed a series of sensitivity analyses as validation of primary MR results.

Results: According to the primary MR estimations and further sensitivity analyses, we established one robust association after Bonferroni correction: the odds ratio (95% CI) per unit change in genetically increased IL-4 was 0.84 (0.89–0.95) for ischemic stroke. The chemokine MCP3 showed a nominally significant association with ischemic stroke risk (OR: 0.93, 95% CI: 0.88–0.99, unadjusted p < 0.05). There was no evidence of a causal effect of other inflammatory cytokines and the risk of ischemic stroke.

Conclusions: Our study suggested that genetically increased IL-4 levels showed a protective effect on the risk of ischemic stroke, which provides important new insights into the potential therapeutic target for preventing ischemic stroke.

Acute Inflammation in Cerebrovascular Disease: A Critical Reappraisal with Focus on Human Studies

Recent attention has been focused on the field of inflammatory biomarkers associated with vascular disorders, regarding diagnosis, prognosis, and possible therapeutical targets. In this study, we aimed to perform a comprehensive review of the literature regarding the use of inflammatory biomarkers in stroke patients. We searched studies that evaluated inflammation biomarkers associated with Cerebrovascular Disease (CVD), namely, ischemic Stroke (IS), Intracerebral Hemorrhage (ICH) and Cerebral Venous Thrombosis (CVT). As of today, neutrophil–lymphocyte ratio (NLR) seems the be the most widely studied and accepted biomarker for cerebrovascular disease due to its easy access and availability. Although demonstrated as a prognostic risk factor, in IS, ICH and CVT, its diagnostic role is still under investigation. Several other prognostic factors could be used or even combined together into a diagnostic or prognostic index. Multiple inflammatory biomarkers appear to be involved in IS, ICH, and CVT. Blood inflammatory cells, easily measured and accessible at admission may provide information regarding accurate diagnosis and prognosis. Although not yet a reality, increasing evidence exists to suggest that these may become potential therapeutic targets, likely influencing or mitigating complications of CVD and improving prognosis. Nevertheless, further larger, well-designed randomized clinical trials are still needed to follow up this hypothesis.

Comprehensive Analysis of Potential miRNA-Target mRNA-Immunocyte Subtype Network in Cerebral Infarction

INTRODUCTION

Cerebral infarction (CI) is one of the leading causes of serious long-term disability and mortality.

OBJECTIVE

We aimed to identify potential miRNAs and target mRNAs and assess the involvement of immunocyte infiltration in the process of CI.

METHODS

First, miRNA and mRNA data were downloaded from the Gene Expression Omnibus database, followed by differential expression analysis. Second, correlation analysis between differentially expressed mRNAs and differential immunocyte subtypes was performed through the CIBERSORT algorithm. Third, the regulatory network between miRNAs and immunocyte subtype-related mRNAs was constructed followed by the functional analysis of these target mRNAs. Fourth, correlation validation between differentially expressed mRNAs and differential immunocyte subtypes was performed in the GSE37587 dataset. Finally, the diagnostic ability of immunocyte subtype-related mRNAs was tested.

RESULTS

Up to 17 differentially expressed miRNAs and 3,267 differentially expressed mRNAs were identified, among which 310 differentially expressed mRNAs were significantly associated with immunocyte subtypes. Several miRNA-target mRNA-immunocyte subtype networks including hsa-miR-671-3p-ZC3HC1-neutrophils, hsa-miR-625-CD5-monocytes, hsa-miR-122-ACOX1/DUSP1/NEDD9-neutrophils, hsa-miR-455-5p-SLC24A4-monocytes, and hsa-miR-455-5p-SORL1-neutrophils were identified. LAT, ACOX1, DUSP1, NEDD9, ZC3HC1, BIN1, AKT1, DNMT1, SLC24A4, and SORL1 had a potential diagnostic value for CI.

CONCLUSIONS

The network including miRNA, target mRNA, and immunocyte subtype may be novel regulators and diagnostic and therapeutic targets in CI.

Search for Reliable Circulating Biomarkers to Predict Carotid Plaque Vulnerability

Atherosclerosis is responsible for 20% of ischemic strokes, and the plaques from the internal carotid artery the most frequently involved. Lipoproteins play a key role in carotid atherosclerosis since lipid accumulation contributes to plaque progression and chronic inflammation, both factors leading to plaque vulnerability. Carotid revascularization to prevent future vascular events is reasonable in some patients with high-grade carotid stenosis. However, the degree of stenosis alone is not sufficient to decide upon the best clinical management in some situations. In this context, it is essential to further characterize plaque vulnerability, according to specific characteristics (lipid-rich core, fibrous cap thinning, intraplaque hemorrhage). Although these features can be partly detected by imaging techniques, identifying carotid plaque vulnerability is still challenging. Therefore, the study of circulating biomarkers could provide adjunctive criteria to predict the risk of atherothrombotic stroke. In this regard, several molecules have been found altered, but reliable biomarkers have not been clearly established yet. The current review discusses the concept of vulnerable carotid plaque, and collects existing information about putative circulating biomarkers, being particularly focused on lipid-related and inflammatory molecules.

Circulating interleukins in relation to coronary artery disease, atrial fibrillation and ischemic stroke and its subtypes: A two-sample Mendelian randomization study

Whether thyroid dysfunction plays a causal role in the development of cancer remains inconclusive. We conducted a two-sample Mendelian randomization study to investigate the associations between genetic predisposition to thyroid dysfunction and 22 site-specific cancers. Single-nucleotide polymorphisms associated with four traits of thyroid function were selected from a genome-wide association meta-analysis with up to 72,167 European-descent individuals. Summary-level data for breast cancer and 21 other cancers were extracted from the Breast Cancer Association Consortium (122,977 breast cancer cases and 105,974 controls) and UK Biobank (367,643 individuals). For breast cancer, a meta-analysis was performed using data from both sources. Genetically predicted thyroid dysfunction was associated with breast cancer, with similar patterns of associations in the Breast Cancer Association Consortium and UK Biobank. The combined odds ratios of breast cancer were 0.94 (0.91–0.98; p = 0.007) per genetically predicted one standard deviation increase in TSH levels, 0.96 (0.91–1.00; p = 0.053) for genetic predisposition to hypothyroidism, 1.04 (1.01–1.07; p = 0.005) for genetic predisposition to hyperthyroidism and 1.07 (1.02–1.12; p = 0.003) per genetically predicted one standard deviation increase in free thyroxine levels. Genetically predicted TSH levels and hypothyroidism were inversely with thyroid cancer; the odds ratios were 0.47 (0.30-0.73; p = 0.001) and 0.70 (0.51-0.98; p = 0.038), respectively. Our study provides evidence of a causal association between thyroid dysfunction and breast cancer (mainly ER-positive tumors) risk. The role of TSH and hypothyroidism for thyroid cancer and the associations between thyroid dysfunction and other cancers need further exploration.

Influence of Interleukin-6 (IL-6) Promoter Gene Polymorphisms (-174G>C, -572G>C, and -597G>A) on IL-6 Plasma Levels and Their Impact in the Development of Acute Ischemic Stroke in Young Indians

This study aimed to determine whether there is an influence of interleukin 6 (IL-6) gene promoter polymorphisms on IL-6 plasma levels and its role in the development of ischemic stroke in young Indians. One hundred young patients with ischemic stroke (age ≥ 45 years) and equal number of age- and sex-matched controls were genotyped for 174G>C, -572G>C, and -597G>A promoter polymorphisms by polymerase chain reaction-restriction fragment length polymorphism. Plasma IL-6 levels were measured by enzyme-linked immunosorbent assay. Plasma IL-6 levels were significantly higher in patients as compared to controls (patients: 28.61 ± 8.61 pg/mL, controls: 7.60 ± 4.10 pg/mL, P = .001). Both -174G>C (allelic χ2/P value: 4.79/.028, genotypic χ2/P value: 5.3/.021) and -572G>C (allelic χ2/P value: 9.63/.00113 Genotypic χ2/P value: 74/.0002) polymorphisms exhibited genotypic as well as allelic significant association with the disease phenotype. Comparison was made between patients and controls for all 3 polymorphisms using a recessive model with respect to plasma IL-6 levels; no polymorphism showed any significant correlative association with the increased IL-6 levels (P = .31, .51, .32). Interleukin 6 is an inflammatory marker that is considerably influenced by nongenetic factors and is not a good candidate gene for studying genetic components associated with ischemic stroke. It seems that the variability in IL-6 levels is an integrated effect of nongenetic influences and the inflammatory events that follow ischemic stroke instead of being its cause. It is suggested that there is no direct association between -174G>C, -572G>C, and -597G>A polymorphisms and elevated IL-6 levels in the development of ischemic stroke.

Association study of CACNA1C polymorphisms with large artery atherosclerotic stroke in Chinese Han population

Aims Ischemic stroke (IS) is one of the most common diseases of neurology and the main cause of death and disability in Chinese population. CACNA1C was considered to be involved in the process of atherosclerosis, but there was little information about the association between genotypic polymorphisms of CACNA1C and ischemic stroke. Our study was designed to elucidate the relationship between four single-nucleotide polymorphisms (SNPs) variants in CACNA1C gene and the risk of large-artery atherosclerotic (LAA) stroke patients. Methods A total of 384 subjects were enrolled in this study, including 192 LAA stroke cases and 192 healthy controls. And four SNPs variants in CNCNA1C gene were genotyped using in-house developed multiplex tagged-amplicon deep sequencing (TAm-Seq). Statistical analysis were conducted using χ2 test and binary logistic regression analysis. Results We found one variant was significantly associated with LAA stroke in the allele models (rs10848683, p = 0.036, OR = 1.371, 95%CI: 1.021-1.841). And rs10848683 was also found to associate with LAA stroke under recessive model (p = 0.027, OR = 0.618, 95% CI: 0.403-0.947) after adjustment for gender and age. We also found that significant difference existed between haplotypes (rs229961-rs215976-rs216008-rs10848683) and LAA stroke (C-T-C-C, p = 0.017, OR = 2.265, 95%CI: 1.136-4.518; G-C-C-C, p = 0.046, OR = 1.891, 95% CI: 1.003-3.565; C-T-C-T, p = 0.001, OR = 0.256, 95%CI: 0.101-0.645). Conclusion The results suggested that there was a potential association between CNCNA1C gene and the risk factor of LAA stroke in Chinese Han population.

Dual Effect of IL-6 -174 G/C Polymorphism and Promoter Methylation in the Risk of Coronary Artery Disease Among South Indians

Inflammation plays an important role in the pathogenesis of atherosclerosis and coronary syndromes; moreover, various lines of evidence suggest that genetic factors do contribute to the risk of coronary artery disease (CAD). The proinflammatory cytokine IL-6 is a central mediator of inflammation associated with CAD. The present study is aimed to investigate the association of single nucleotide polymorphism in the promoter region of the IL-6 gene (-174 G > C) and methylation with the susceptibility of CAD. Genotyping of IL-6 -174 G/C polymorphism was performed by PCR-RFLP. Methylation-specific PCR method was used to study the IL-6 gene promoter methylation. Analysis of 470 subjects (265 CAD patients and 205 controls) showed association of the -174 G/C variant with the CAD risk in dominant model (OR 1.58, 95% CI, 1.024-2.23, P = 0.04). Further, the analysis of the distribution of genotypes and alleles of -174 G > C polymorphism according to clinical features of CAD, revealed significant association of genotype and allele (OR 1.86, 95% CI 1.18-2.84 P = 0.01, and OR 1.71, 95% CI 1.09-2.23 P = 0.02 respectively) with diabetes, and we found no association with hypertension (OR 0.95, 95% CI 0.57-1.59, P = 0.8). We also analyzed the methylation status of IL-6 promoter region between cases and controls showed significant hypo methylation in CAD subjects (OR 2.36, 95% CI 1.51-4.259, P = 0.006). Additionally, GC, CC genotypes and C allele carriers show hypomethylation in CAD cases compared to controls (54.58 vs. 76.85%, 29.83 vs. 40% respectively). In conclusion, the promoter polymorphism -174 G/C is associated with CAD risk and further carriers of 'C' allele at -174 locus showed significant hypo methylation which could contribute to increased risk of CAD. The present study highlights the association of allele and genotypes with differential DNA methylation of CpG islands in the IL-6 promoter region which may affect IL-6 gene regulation.

Association of CYP2J2 gene polymorphisms with ischemic stroke and stroke subtypes in Chinese population

BACKGROUND AND PURPOSE

Ischemic stroke (IS) is the main cause of mortality and disability among the old people in China and is a multifactorial disease influenced by many factors including genetic factors like the allele for CYP 2J2. It has been demonstrated that CYP2J2 polymorphisms alter the transcriptional activity. However, studies on the association between CYP2J2-50G/T polymorphism and IS have reported conflicting results. Thus, our study aimed to examine the association between 4 variants in the CYP2J2 gene and the risk of IS and its subtypes, in the Chinese population.

MATERIALS AND METHODS

In this study, genotyping was performed by using polymerase chain reaction (PCR) sequencing for 202 IS patients and 206 age- and sex-matched controls. Odds ratios (ORs) and confidence interval (CI) were estimated by multivariate logistic regression and PCR results were confirmed by DNA sequencing. A meta-analysis was conducted to evaluate the association of CYP2J2-50G>T polymorphism with the risk of IS in Chinese population by calculating pooled OR.

RESULTS

We found this polymorphism was significantly associated with IS (17.82% vs. 10.68%, P = 0.039). Multiple logistic regression analysis revealed that GT genotype was associated with a significantly high risk of IS (OR = 2.32, 95% CI: 1.21-4.45, P = 0. 011) after adjustment for other confounding factors such as hypertension, diabetes, heart disease, smoking habit, family history, triglyceride and low-density lipoprotein levels. We also found a significant association of GT genotype with small artery occlusion (SAA) (P < 0.05; OR = 2.22; 95% CI: 1.043-4.72). Meta-analysis results also showed that the GT genotype carriers had a negative effect on the risk of IS in Chinese population with overall OR of 1.40 (95% CI: 1.06-1.84).

CONCLUSION

The findings of the present study suggested that polymorphism in -50G/T position of CYP2J2 gene might be a risk factor for IS in Chinese population. Further large prospective studies were required to confirm these findings.

Relationship between Interleukin-6 (-174G/C and -572C/G) Promoter Gene Polymorphisms and Risk of Intracerebral Hemorrhage: A Meta-Analysis

BACKGROUND

Polymorphisms of -174G/C and -572C/G in the Interleukin-6 (IL-6) promoter gene can affect both transcription and secretion of IL-6 and may be involved in the inflammatory mechanisms in early and delayed phases after intracerebral hemorrhage (ICH). The role of these polymorphisms remains unclear for the pathogenesis of ICH.

METHODS

PubMed, EMBASE, MEDLINE and Google Scholar searches were conducted from January 1, 1950 to February 29, 2016 and were supplemented with relevant articles identified in the references. The following search terms were used: ('interleukin-6' or 'IL-6') and ('genetic polymorphism' or 'single nucleotide polymorphisms' or 'SNP') and ('intracerebral hemorrhage' or 'ICH') and ('hemorrhagic stroke' or 'HS'). Fixed or random effects models were used to estimate the pooled odds ratios and 95% confidence intervals. Begg's funnel plot was used to assess the potential for publication bias.

RESULTS

In our meta-analysis, three case-control studies involving 446 ICH cases and 2,322 controls were included. No significant association was observed for the IL-6 (-174G/C and -572C/G) gene polymorphisms with the risk of ICH under dominant, recessive and allelic models.

CONCLUSION

Our meta-analysis suggests that IL-6 gene polymorphisms are not associated with the risk of ICH. However, caution must be taken while considering the results of our meta-analysis due to the presence of small sample size. Our results cannot be extrapolated to represent the effect of entire IL-6 genetic polymorphism on stroke patients worldwide. Therefore, further well-designed studies with large sample size are warranted to validate our findings and provide a profound conclusion.

Association of serum immunoglobulin-G to Porphyromonas gingivalis with acute cerebral infarction in the Chinese population

Background/Purpose:

There is evidence supporting an association between ischemic stroke and periodontitis in western countries. Differing genetic backgrounds and lifestyles among populations may affect this association. The aim of our study was to determine whether antibody titers to Porphyromonas gingivalis are associated with acute cerebral infarction in the Chinese population.

Materials and Methods:

This case-control study was conducted on 88 acute cerebral infarction patients and 40 healthy control subjects. Serum immunoglobulin-G (IgG) antibody to P. gingivalis was analyzed by enzyme-linked immune sorbent assay. Serum lipids were determined with the automatic biochemical analyzer. Fibrinogen was measured using automated coagulation analyzer. High-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6) were quantified using commercial ELISA kits. The intima-media thickness of the common carotid arteries (IMT-CCA) was measured by ultrasonography.

Results:

The results showed that P. gingivalis IgG antibody levels were significantly higher in acute cerebral infarction cases than in healthy controls (mean ± standard deviation, 11.06 ± 1.49 vs. 9.15 ± 1.70, P < 0.001). There were significant correlations of P. gingivalis IgG titer with total cholesterol (r = 0.34, P = 0.001), low-density lipoprotein (r = 0.39, P < 0.001), apolipoprotein-B (r = 0.30, P = 0.004), hs-CRP (r = 0.35, P = 0.001), IL-6 (r = 0.27, P = 0.011), and IMT-CCA (left: r = 0.306, P = 0.004; right: r = 0.241, P = 0.024).

Conclusion:

Antibody titers to P. gingivalis are associated with acute cerebral infarction in the Chinese population.

Linkage and association between interleukin-6 gene polymorphisms and ischemic stroke: a family-based study in the northern Chinese Han population

BACKGROUND

Numerous genetic risk factors of ischemic stroke (IS) have been reported from both candidate gene and genome-wide strategies with inconsistent results. The objective of this study was to confirm the relationship between 10 previously identified single-nucleotide polymorphisms (SNPs) and IS in the Chinese population.

METHODS

A family-based study was conducted in a rural area of Beijing, with a total of 227 IS families with 622 participants recruited. Both linkage and association analyses were performed, with all the sibling pairs derived from the 227 families analyzed using the sib-pair test of model-free linkage to assess linkage between SNPs and IS, with association analyses including a family-based association test (FBAT) and generalized estimating equations (GEE).

RESULTS

Nonparametric linkage analysis revealed that the rs1800796 polymorphism in the interleukin-6 (IL-6) gene is significantly linked to the small arterial occlusion (SAO) subtype (p=0.022), while the rs7193343 polymorphism in the ZFHX3 gene is linked to IS (p=0.002) under the dominant model. Significant allelic associations were identified between the G allele of rs1800796 and IS (p=0.042) and the SAO subtype (p=0.025) in the FBAT. The GEE method revealed that the G allele of rs1800796 increased IS risk by 1.55-fold (95% 95% confidence interval [CI]: 1.01, 2.37; p=0.043) and 2.43-fold (95% CI: 1.32, 4.45; p=0.004) in the SAO subtype in the dominant model, which correlated with the significant associations detected in the FBAT.

CONCLUSIONS

In this study, we confirmed that the SNP of rs1800796 in the IL-6 gene is related to IS and the SAO subtype using different statistical approaches. These findings could contribute to identifying individuals with a high IS risk.

Volume of the hippocampal subfields in healthy adults: differential associations with age and a pro-inflammatory genetic variant

The hippocampus is one of the most age-sensitive brain regions, yet the mechanisms of hippocampal shrinkage remain unclear. Recent studies suggest that hippocampal subfields are differentially vulnerable to aging and differentially sensitive to vascular risk. Promoters of inflammation are frequently proposed as major contributors to brain aging and vascular disease but their effects on hippocampal subfields are unknown. We examined the associations of hippocampal subfield volumes with age, a vascular risk factor (hypertension), and genetic polymorphisms associated with variation in pro-inflammatory cytokines levels (IL-1β C-511T and IL-6 C-174G) and risk for Alzheimer's disease (APOEε4) in healthy adult volunteers (N = 80; age = 22-82 years). Volumes of three hippocampal subfields, cornu ammonis (CA) 1-2, CA3-dentate gyrus, and the subiculum were manually measured on high-resolution magnetic resonance images. Advanced age was differentially associated with smaller volume of CA1-2, whereas carriers of the T allele of IL-1β C-511T polymorphism had smaller volume of all hippocampal subfields than CC homozygotes did. Neither of the other genetic variants, nor diagnosis of hypertension, was associated with any of the measured volumes. The results support the notion that volumes of age-sensitive brain regions may be affected by pro-inflammatory factors that may be targeted by therapeutic interventions.

Interleukin-6 gene polymorphism, chronic stress and atherosclerosis: interleukin-6-174G>C polymorphism, chronic stress and risk of early atherosclerosis in the Cardiovascular Risk in Young Finns Study

OBJECTIVE

Interleukin-6 protein has been suggested as a mediator connecting chronic stress and cardiovascular diseases. We investigated whether the functional G174C polymorphism (rs1800795) of interleukin-6 gene is associated with vital exhaustion, a measure of chronic stress, or with preclinical atherosclerosis.

METHODS

Associations between the interleukin-6-174G>C polymorphism, preclinical atherosclerosis, and vital exhaustion were examined in 1673 women and men aged 24-39years participating in the Cardiovascular Risk in Young Finns study. Vital exhaustion was measured using Maastricht Questionnaire. Preclinical atherosclerosis was assessed by carotid intima-media thickness using ultrasound techniques. DNA was genotyped for the interleukin-6-174G>C polymorphism (rs1800795).

RESULTS

The GG genotype of the interleukin-6-174G>C polymorphism was associated with higher vital exhaustion. Moreover, higher vital exhaustion was associated with greater intima-media thickness in men carrying G alleles, adjusted for cardiovascular risk factors.

CONCLUSION

Our findings support a role for the interleukin-6-174G>C polymorphism in increased risk of atherosclerosis in individuals with chronic stress. In addition, individuals carrying the G allele of the interleukin-6-174G>C polymorphism may be more prone to adverse effects of psychosocial stress.

Association of IL-6-174G > C and -572C > G polymorphisms with risk of young ischemic stroke patients

AIM

To investigate the association between interleukin-6 (IL-6) -174G>C and -572C>G polymorphisms and risk for ischemic stroke (IS) in young patients.

METHODS

We genotyped IL-6 -174G>C and -572C>G in a case-control study of 430 young IS patients and 461 control subjects. An unconditional multiple logistical regression model was used to calculate the effects of IL-6-174G>C and -572C>G polymorphisms on IS risk.

RESULTS

Higher body mass index, diabetes, hypertension, obesity, and smoking were associated with risk of ischemic stroke. Multivariate regression analyses showed that subjects carrying the -174CC genotype (OR=1.69, 95% CI=1.16-2.57) and C allele (OR=1.37, 95% CI=1.09-1.67) had a small but significant increased risk of IS. Similarly, those carrying the -572GG genotype (OR=2.12, 95% CI=1.18-3.82) and G allele (OR=1.43, 95% CI=1.14-1.83) had a moderate increased risk of IS. We found the -174G>C and -572C>G polymorphisms interact with hypertension and obesity.

CONCLUSION

Our results suggest that polymorphisms in IL-6-174G>C and -572C>G are associated with IS risk in young patients, and that these polymorphisms interact with hypertension, obesity and etiologic subtypes. These findings could be helpful in identifying individuals at increased risk for developing IS.

Association of intercellular adhesion molecular-1 gene polymorphism in ischemic stroke patients

BACKGROUND

Ischemic stroke (IS) is a prevalent disease causing a body disability, the third leading cause of death in Taiwan. It shows that the level of intercellular adhesion molecular-1 (ICAM-1) in IS patients is higher than control subjects.

OBJECTIVE

This study is to investigate the possible association of ICAM-1 (G1548A) polymorphism in IS patients.

MATERIALS AND METHODS

A total of 646 subjects were enrolled in this study, including 312 IS patients, and 334 controls without a history of symptomatic IS. The ICAM-1 (G1548A) polymorphism was analyzed by polymerase chain reaction and restriction fragment length polymorphism. Clinical factors were also determined.

RESULTS

The frequencies of the ICAM-1 (G1548A) polymorphism for G/G, G/A, and A/A were 74.8%, 23.9%, and 0.3%, respectively, in healthy controls, and 62.8%, 32.1%, and 5.1%, respectively, in patients. The frequency of the ICAM-1 (G1548A) A allele (21.2% versus 13.2%, respectively; P = 0.007) and the carriers of the ICAM-1 (G1548A) A allele (37.2% versus 25.2%; P = 0.019, OR 1.76, 95% CI 1.1-2.83) are great in IS patients compared with healthy controls. There is a higher risk of IS associated with homozygosity for the ICAM-1 (G1548A) A allele (AA genotype) compared with the control population (5.1% vs. 0.3%, respectively, P = 0.04; OR 5.1, 95% CI 1.19-21.66). We also observed both hypertension and diabetes has shown a positive association with IS.

CONCLUSIONS

The ICAM-1 (G1548A) polymorphism was associated with independent risk factor for the development of IS.

Interleukin 6 plasma concentration associates with cognitive decline: the northern Manhattan study

BACKGROUND

Interleukin 6 (IL-6) is an inflammatory cytokine that has been associated with vascular disease and cognitive impairment, but few studies have examined these relationships in population-based studies that include Hispanic and Black people who often have a greater prevalence of vascular risk factors and are at an elevated risk of dementia than Whites. We examined relative elevations of plasma IL-6 concentrations in relation to cognitive decline in a stroke-free racially/ethnically diverse community-based sample from Northern Manhattan.

METHODS

We used mixed effects models to measure the effect of IL-6 on change in performance on the modified Telephone Interview for Cognitive Status (TICS-m) measured annually in our cohort, adjusting for sociodemographic and vascular risk factors.

RESULTS

There were 1,224 participants with IL-6 levels (median 1.5 pg/ml, interquartile range 0.83-2.57 pg/ml) and TICS-m data available (mean = 31.6 points, SD 6.5). The mean age was 71 (SD 9.3; 64% women, 59% Hispanic, 19% Black, 19% White) with 3,406 person-years and a median 3.0 years of follow-up (interquartile range 1.1-4.0 years). Participants with IL-6 levels above the median showed greater cognitive decline on the TICS-m compared to those with levels below the median, adjusting for sociodemographic and vascular factors (β = -0.17 points/year, p = 0.02). Decline on the TICS-m among participants with IL-6 above the median differed by age (p for interaction <0.001). There was no interaction by race/ethnicity, vascular risk factors, C-reactive protein, apolipoprotein ε4 allele status, or the metabolic syndrome among nondiabetics.

CONCLUSIONS

IL-6 associated with cognitive decline among older participants in this racially/ethnically diverse sample independent of other vascular risk factors and C-reactive protein.

Interleukin-6, a major cytokine in the central nervous system

Interleukin-6 (IL-6) is a cytokine originally identified almost 30 years ago as a B-cell differentiation factor, capable of inducing the maturation of B cells into antibody-producing cells. As with many other cytokines, it was soon realized that IL-6 was not a factor only involved in the immune response, but with many critical roles in major physiological systems including the nervous system. IL-6 is now known to participate in neurogenesis (influencing both neurons and glial cells), and in the response of mature neurons and glial cells in normal conditions and following a wide arrange of injury models. In many respects, IL-6 behaves in a neurotrophin-like fashion, and seemingly makes understandable why the cytokine family that it belongs to is known as neuropoietins. Its expression is affected in several of the main brain diseases, and animal models strongly suggest that IL-6 could have a role in the observed neuropathology and that therefore it is a clear target of strategic therapies.

Interleukin 6-174G>C polymorphism and risk of aneurysmal subarachnoid hemorrhage: case-control study and meta-analysis

OBJECTIVES

Vascular inflammation contributes to the pathogenesis of aneurysmal subarachnoid hemorrhage (aSAH). Interleukin 6 (IL6) is a proinflammatory cytokine involved in many vascular pathologies. Two studies analyzing an association of the functional IL6 gene -174G>C promoter polymorphism with aSAH provided inconsistent results. The aim of this study was to investigate whether this IL6 polymorphism is associated with aSAH in a Polish population.

MATERIAL AND METHODS

We genotyped 276 aSAH patients and 581 unrelated control subjects. All were of Caucasian origin. In addition, a meta-analysis combining results of the current and previously published studies was conducted.

RESULTS

The distribution of IL6 genotypes and alleles did not differ significantly between aSAH (GG - 29.7%, GC - 50.0%, CC - 20.2%, G - 54.7%) and control subjects (GG - 32.0%, GC - 47.3%, CC - 20.7%, G - 44.3%). In the meta-analysis, the IL6-174G>C polymorphism was not associated with aSAH risk either.

CONCLUSIONS

We failed to find an association between the IL6 -174G>C polymorphism and aSAH in analyzed European populations.

Variants in the inflammatory IL6 and MPO genes modulate stroke susceptibility through main effects and gene-gene interactions

There is substantial evidence that inflammation within the central nervous system contributes to stroke risk and recovery. Inflammatory conditions increase stroke risk, and the inflammatory response is of major importance in recovery and healing processes after stroke. We investigated the role of inflammatory genes IL1B, IL6, MPO, and TNF in stroke susceptibility and recovery in a population sample of 672 patients and 530 controls, adjusting for demographic, clinical and lifestyle risk factors, and stroke severity parameters. We also considered the likely complexity of inflammatory mechanisms in stroke, by assessing the combined effects of multiple genes. Two interleukin 6 (IL6) and one myeloperoxidase (MPO) single-nucleotide polymorphisms were significantly associated with stroke risk (0.022<(corrected)P<0.042), highlighting gene variants of low to moderate effect in stroke risk. An epistatic interaction between the IL6 and MPO genes was also identified in association with stroke susceptibility (P=0.031 after 1,000 permutations). In a subset of 546 patients, one IL6 haplotype was associated with stroke outcome at 3 months ((corrected)P=0.024), an intriguing finding warranting further validation. Our findings support the association of the IL6 gene and present novel evidence for the involvement of MPO in stroke susceptibility, suggesting a modulation of stroke risk by main gene effects, clinical and lifestyle factors, and gene-gene interactions.

WNT/β-catenin pathway is modulated in asthma patients and LPS-stimulated RAW264.7 macrophage cell line

In the present study, we investigated the possibility that the WNT/β-catenin pathway plays a role in inflammatory responses both in an human inflammatory condition and in an in vitro inflammation model. First, we analyzed gene expression patterns of the peripheral blood cells from asthma patients compared with those from normal subjects using microarray analyses. We found that intracellular signaling molecules of the WNT/β-catenin pathway were significantly changed in asthma patients compared with the levels in the controls. Next, we determined whether major components of the WNT/β-catenin pathway were involved in the lipopolysaccharide (LPS)-induced inflammatory response of the RAW264.7 macrophage cell line. Among the members of WNT/β-catenin pathway, the protein levels of low-density lipoprotein receptor-related protein (LRP) 6, dishevelled (DVL) 2, and AXIN1, which were measured using western blotting, did not significantly change in the presence of LPS. In contrast, the LPS induced a rapid phosphorylation of glycogen synthase kinase (GSK) 3β and accumulation of β-catenin protein. It was found that β-catenin plays a significant role in the LPS-induced inflammatory response through the performance of small interfering RNA (siRNA) transfection experiments. The mRNA level of IL-6 was significantly elevated in β-catenin siRNA-transfected cells compared with that in control siRNA-transfected cells after LPS treatment. Furthermore, nuclear factor-κB (NF-κB) activity was also significantly increased in β-catenin siRNA-transfected cells compared with the level seen in control siRNA-transfected cells. Taken together, these results suggest that β-catenin plays a role as a negative regulator, preventing the overproduction of inflammatory cytokines such as IL-6 in LPS-induced inflammatory responses.

The G to A polymorphism at -597 of the interleukin-6 gene is extremely rare in southern Han Chinese

Interleukin-6 (IL-6) is a cytokine involved in different physiologic and pathophysiologic processes including essential hypertension (EH). Associations of the IL-6 promoter region polymorphisms with circulating level of IL-6 have been reported in various studies. We detected the IL-6-597G/A polymorphism in 246 EH patients and 194 healthy controls from Jiangsu area (south of China). Individuals all carried the GG wild genotype, no GA or AA genotypes were found. Our results suggest that IL-6-597G/A polymorphism is extremely rare and unlikely to be contributing significantly to disease susceptibility in southern Han Chinese.

Does Inflammation Predispose to Recurrent Vascular Events after Recent Transient Ischaemic Attack and Minor Stroke? the North West of England Transient Ischaemic Attack and Minor Stroke (NORTHSTAR) Study

Background and hypothesis

Inflammation is implicated in the pathogenesis and outcome of ischaemic injury. Poststroke inflammation is associated with outcome but it remains unclear whether such inflammation precedes or results from ischaemic injury. We hypothesised that inflammatory markers are associated with an increased risk of recurrent vascular events soon after transient ischaemic attack and minor stroke.

Methods

This was a multicentre, prospective, nested case–control study. Plasma concentrations of C-reactive protein, interleukin-6, interleukin-1-receptor antagonist and fibrinogen, leucocyte counts, erythrocyte sedimentation rate and inflammatory gene allele frequencies were analysed in 711 patients with recent transient ischaemic attack or minor stroke. Cases were defined by the incidence of one or more recurrent vascular events during the three-month follow-up. Association of inflammatory markers with case-status was determined using conditional logistic regression.

Results

Plasma concentrations of C-reactive protein, interleukin-1-receptor antagonist and interleukin-6 were not associated with case-status. In secondary analyses, only erythrocyte sedimentation rate was significantly associated with case-status (odds ratio 1·39, 95% confidence interval 1·03–1·85; P=0·03), but this effect did not persist after adjustment for smoking and past history of transient ischaemic attack or stroke. Single nucleotide polymorphisms in four inflammatory genes (interleukin-6, fibrinogen, P-selectin and vascular cell adhesion molecule-1) were nominally associated with case-status.

Conclusions

Circulating inflammatory markers were not associated with recurrent vascular events. Nominally significant associations between genetic markers and case-status will require replication. These data provide little evidence for an inflammatory state predisposing to stroke and other vascular events in a susceptible population.

Genetics of stroke

Stroke is the second most common cause of death and the most common cause of disability in developed countries. Stroke is a multi-factorial disease caused by a combination of environmental and genetic factors. Numerous epidemiologic studies have documented a significant genetic component in the occurrence of strokes. Genes encoding products involved in lipid metabolism, thrombosis, and inflammation are believed to be potential genetic factors for stroke. Although a large group of candidate genes have been studied, most of the epidemiological results are conflicting. Studies of stroke as a monogenic disease have made huge progress, and animal models serve as an indispensable tool to dissect the complex genetics of stroke. In the present review, we provide insight into the role of in vivo stroke models for the study of stroke genetics.

Implications of genetic polymorphisms in inflammation-induced atherosclerosis

Inflammation is the mainstay of atherosclerosis and is an important governing factor at all stages of the disease process from lesion formation to plaque build-up and final end-stage rupture and thrombosis. An overview of the numerous clinico-epidemiological studies on the association between inflammatory gene polymorphisms and Cardiovascular disease (CVD) and its co-morbidities have shown that the risk associated with any single genotype is modest while the haplotypes, especially those defined on the basis of tag-SNP approach, have better coverage of the gene and show moderately higher impact on disease risk. Nevertheless, even these associations have been inconsistent with low cross-race repeatability. This has been attributed to many plausible causes such as clinical heterogeneity, sample selection criteria, variable genetic landscapes across different ethnic groups, confounding effect of co-morbidities etc. On the other hand, unbiased studies such as the family-based linkage and case-control based associations that have taken into account, thousands of genotypic markers spanning the whole genome, have had the ability to identify novel genetic loci for coronary artery disease. These studies have shown that many inflammatory genes are involved in the regulation of specific biomarkers of inflammation that collectively contribute to the disease-associated risk. In addition, there appears to be considerable cross talk between the different biochemical and metabolic processes. Therefore, consideration of all these factors can build towards an 'atherosclerotic bionetwork' that can refine our quest for developing a robust risk stratification tool for cardiovascular disease.

Commonly studied polymorphisms in inflammatory cytokine genes show only minor effects on mortality and related risk factors in nonagenarians

Systemic low-grade inflammation is consistently associated with functional status, cognitive functioning, multimorbidity, and survival in oldest olds. If inflammation is either a cause or a consequence of age-related pathology, genetic determinants of late-life survival can reside in cytokine genes polymorphisms, regulating inflammatory responses. The aim of this study was to test associations between commonly studied polymorphisms in interleukin (IL)6, IL10, IL15, and IL18, and tumor necrosis factor-alpha genes and late-life survival in a longitudinal cohort of nonagenarians: the Danish 1905 cohort. Additionally, associations were investigated between inflammatory markers and major predictors of mortality as cognitive and functional status. Modest sex-specific associations were found with survival, cognitive functioning, and handgrip strength. Evaluation of combined genotypes indicated that, in nonagenarian men, the balance of pro- and anti-inflammatory activity at IL18 and IL10 loci is protective against cognitive decline. In conclusion, in this large study with virtually complete follow-up, commonly studied polymorphisms in cytokine genes do not have a major impact on late-life survival or associated risk phenotypes.

Ambivalent aspects of interleukin-6 in cerebral ischemia: inflammatory versus neurotrophic aspects

Interleukin-6 (IL-6) is pleiotropic cytokine involved in many central nervous system disorders including stroke, and elevated serum IL-6 has been found in acute stroke patients. IL-6 is implicated in the inflammation, which contributes to both injury and repair process after cerebral ischemia. However, IL-6 is one of the neurotrophic cytokines sharing a common receptor subunit, gp130, with other neurotrophic cytokines, such as leukemia inhibitory factor (LIF) and ciliary neurotrophic factor. The expression of IL-6 is most prominently identified in neurons in the peri-ischemic regions, and LIF expression shows a similar pattern. The direct injection of these cytokines into the brain after ischemia can reduce ischemic brain injury. The cytokine receptors are localized on the neuron surface, suggesting that neurons are the cytokine target. The major IL-6 downstream signaling pathway is JAK-STAT, and Stat3 activation occurs mainly in neurons during postischemic reperfusion. Further investigation is necessary to clarify the exact role of Stat3 signaling in neuroprotection. Taken together, the information suggests that IL-6 plays a double role in cerebral ischemia, as an inflammatory mediator during the acute phase and as a neurotrophic mediator between the subacute and prolonged phases.

Pro-inflammatory and anti-inflammatory cytokines in acute ischemic stroke and their relation to early neurological deficit and stroke outcome

OBJECTIVES

Our aim was to explore (i) the difference in concentration of IL-6, TNF-alpha and IL-10 between acute ischemic stroke patients and control individuals; (ii) the association of plasma cytokine concentration with stroke severity at admission assessed by NIHSS and stroke outcome in 90 days assessed by Barthel index (BI) and modified Rankin scale (mRS).

MATERIALS AND METHODS

Study included 68 stroke patients admitted within 12 h of symptoms onset and 71 controls.

RESULTS

IL-6 was increased in patients relative to controls (P=0.035) and this increase was associated with severe stroke (P=0.007) and worse outcome (P=0.030 and 0.019; assessed by BI and mRS, respectively), whereas IL-10 was decreased (P=0.044) and associated with better outcome (P=0.043). TNF-alpha did not differ between studied groups (P=0.302).

CONCLUSIONS

Increased IL-6 and reduced IL-10 concentrations are present in early stroke period and are associated with a degree of neurological deficit and/or stroke outcome.