Interleukin-18 promoter polymorphisms and risk of ischemic stroke

The Role of Interleukin-18 in the Development and Progression of Atherosclerosis

Atherosclerosis (AS), as a chronic inflammatory disorder of the cardiovascular system, is one of the leading causes of ischemic heart disease, stroke and peripheral vascular disease. There is growing evidence on the role of innate and adaptive immunity in the pathogenesis of atherosclerosis. Interleukin-18 is one of the novel proinflammatory cytokines involved in atherogenesis, atherosclerotic plaque instability and plaque rupture. In this review, we overview the findings of preclinical and clinical studies about the role and mechanism of action of IL-18 in the pathogenesis of AS, which could offer novel prognostic and therapeutic approaches.

Investigation of The Relationship Between IL-18 (-607 C/A), IL-18 (-137 G/C) Gene Variations and Ischemic Stroke Disease Development in Thrace Region of Turkey

BACKGROUND

Ischemic stroke is a clinical condition characterized by focal or global cerebral dysfunction resulting from inhibition of brain blood flow. Genetic factors play an important role in the pathogenesis of ischemic stroke. As a result of IL-18 (-607 C/A, -137 G/C) gene variations, it is thought that binding of transcription factors may be affected and IL-18 mRNA expression can be modulated. Therefore, the purpose of our study is to investigate the roles of IL-18 (-607 C/A), IL-18 (-137 G/C) gene variations in the development of ischemic stroke in Trakya Region of Turkey.

METHODS

Our study was performed with 90 ischemic stroke patients and 89 healthy controls. Genotype distributions of IL-18 (-607 C/A, -137 G/C) gene variations were determined using polymerase chain reaction (PCR) method.

RESULTS

GC genotype and CA genotype of IL-18 (-137 G/C) and IL-18 (-607 C/A) gene variations were determined higher significantly in patent group as compared with other genotypes. However, the statistically significant difference was not determined between patients with ischemic stroke and healthy control groups in terms of IL-18 (-137 G/C) and IL-18 (-607 C/A) gene variations (p > 0,05). Allele frequencies of IL-18 (-137 G/C) and IL-18 (-607 C/A) in patient and control groups were significantly different from the Hardy-Weinberg distribution (p < .001 for all).

CONCLUSION

Although these gene variations' genotype distributions were not determined as a genetic risk factor for the development of ischemic stroke, allele frequencies of IL-18 (-137 G/C) and IL-18 (-607 C/A) in patient and control groups were significantly different from the Hardy-Weinberg distribution.

Targeting Oxidative Stress and Inflammation to Prevent Ischemia-Reperfusion Injury

The cerebral ischemia injury can result in neuronal death and/or functional impairment, which leads to further damage and dysfunction after recovery of blood supply. Cerebral ischemia/reperfusion injury (CIRI) often causes irreversible brain damage and neuronal injury and death, which involves many complex pathological processes including oxidative stress, amino acid toxicity, the release of endogenous substances, inflammation and apoptosis. Oxidative stress and inflammation are interactive and play critical roles in ischemia/reperfusion injury in the brain. Oxidative stress is important in the pathological process of ischemic stroke and is critical for the cascade development of ischemic injury. Oxidative stress is caused by reactive oxygen species (ROS) during cerebral ischemia and is more likely to lead to cell death and ultimately brain death after reperfusion. During reperfusion especially, superoxide anion free radicals, hydroxyl free radicals, and nitric oxide (NO) are produced, which can cause lipid peroxidation, inflammation and cell apoptosis. Inflammation alters the balance between pro-inflammatory and anti-inflammatory factors in cerebral ischemic injury. Inflammatory factors can therefore stimulate or exacerbate inflammation and aggravate ischemic injury. Neuroprotective therapies for various stages of the cerebral ischemia cascade response have received widespread attention. At present, neuroprotective drugs mainly include free radical scavengers, anti-inflammatory agents, and anti-apoptotic agents. However, the molecular mechanisms of the interaction between oxidative stress and inflammation, and their interplay with different types of programmed cell death in ischemia/reperfusion injury are unclear. The development of a suitable method for combination therapy has become a hot topic.

Association between interleukin-18 (137G/C and 607C/A) gene polymorphisms and risk of ischemic stroke: a meta-analysis

Over the years, numerous researchers have explored the relationship between ischemic stroke (IS) and interleukin-18 (IL-18) gene polymorphisms. However, those studies reported conflicting and ambiguous results. The effects of IL-18 (137G/C and 607C/A) genetic variants on IS were investigated in this article. We performed a systematic search that was comprehensively executed in online databases for studies published up to 30 April 2018. Calculation of pooled odds ratios (ORs) and 95% confidence intervals was applied to assess the intensity of correlation using Stata.12.0. The overall outcome showed that 137G allele increased the risk of IS under the homozygous model (OR=1.36, P=0.027). Nevertheless, on the basis of ethnicity for the subgroup analysis (Asian and Egyptian), it was disclosed that the association was only found in the Egyptian population under the allelic model (OR=2.72, P=0.001) and recessive model (OR=5.04, P=0.000). In the overall analysis, 607C allele increased the risk of IS under all hereditary models (C vs. A: OR=1.26, P=0.002; CC vs. AA: OR=1.67, P=0.002; CA vs. AA: OR=1.30, P=0.001; CC+CA vs. AA: OR=1.41, P=0.000; CC vs. AA+CA: OR=1.48, P=0.000); a similar trend was observed in the Asian population. However, 607C allele was linked to decreased IS risk in the Egyptian population under all genetic models except the heterozygous model (C vs. A: OR=0.48, P=0.006; CC vs. AA: OR=0.19, P=0.007; CA vs. AA: OR=0.47, P=0.078; CC+CA vs. AA: OR=0.39, P=0.020; CC vs. AA+CA:OR=0.30, P=0.030). Although two polymorphisms were associated with IS, the association varied significantly in different countries. Large epidemiological studies will be required to verify these findings in the future.

Increased Expression of Interleukin-18 mRNA is Associated with Carotid Artery Stenosis

Background:

Carotid artery stenosis is the atherosclerotic narrowing of the proximal internal carotid artery and one of the primary causes of stroke. Elevated expression of the pleiotropic proinflammatory cytokine interleukin-18 has been demonstrated in human atherosclerotic plaques.

Aims:

To investigate whether the mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 −137 G/C (rs187238) variants are associated with carotid artery stenosis development.

Study Design:

Case-control study.

Methods:

The mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 rs187238 variants were evaluated by quantitative real-time polymerase chain reaction and real-time polymerase chain reaction, respectively, in the peripheral blood mononuclear cells of 70 patients with carotid artery stenosis (36 symptomatic, 34 asymptomatic) and 75 healthy controls.

Results:

Interleukin-18 mRNA expression was significantly increased in carotid artery stenosis patients compared to that in healthy controls (p=0.01). However, no significant difference was observed between interleukin-18-binding protein mRNA expression levels in patients with carotid artery stenosis and those in controls (p=0.101). Internal carotid artery stenosis severity was significantly higher in symptomatic patients than that in asymptomatic patients (p<0.001). A significant relationship was identified between interleukin-18 expression and internal carotid artery stenosis severity in patients with carotid artery stenosis (p=0.051). Interleukin-18 rs187238 polymorphism genotype frequencies did not significantly differ between patients with carotid artery stenosis and controls (p=0.246). A significant difference was identified between interleukin-18-binding protein gene expression and symptomatic and asymptomatic patients (p=0.026), but there was no difference in interleukin-18 expression between the symptomatic and asymptomatic subgroups (p=0.397).

Conclusion:

Interleukin-18 mRNA expression may affect carotid artery stenosis etiopathogenesis and internal carotid artery stenosis severity and also may play a mechanistic role in the pathogenesis of carotid artery stenosis, influencing the appearance of symptoms.

Association between genetic polymorphisms of interleukins and cerebral infarction risk: a meta-analysis

Interleukins (ILs) are the most typical inflammatory and immunoregulatory cytokines. Evidences have shown that polymorphisms in ILs are associated with cerebral infarction risk. However, the results remain inconclusive. The present study was to evaluate the role of ILs polymorphisms in cerebral infarction susceptibility. Relevant case-control studies published between January 2000 and December 2015 were searched and retrieved from the electronic databases of Web of Science, PubMed, Embase and the Chinese Biomedical Database. The odds ratio (OR) with its 95% confidence interval (CI) were employed to calculate the strength of association. A total of 55 articles including 12619 cerebral infarction patients and 14436 controls were screened out. Four ILs (IL-1, IL-6, IL-10 and IL-18) contained nine single nucleotide polymorphisms (SNPs; IL-1α -899C/T, IL-1β -511C/T and IL-1β +3953C/T; IL-6 -174G/C and -572C/G; IL-10 -819C/T and -1082A/G; IL-18 -607C/A and -137G/C). Our result showed that IL-1α -899C/T and IL-18 -607C/A (under all the genetic models), and IL-6 -572C/G (under the allelic model, heterogeneity model and dominant model) were associated with increased the risk of cerebral infarction (P<0.05). Subgroup analysis by ethnicity showed that IL-6 -174G/C polymorphism (under all the five models) and IL-10 -1082A/G polymorphism (under the allelic model and heterologous model) were significantly associated with increased the cerebral infarction risk in Asians. Other genetic polymorphisms were not related with cerebral infarction susceptibility under any genetic models. In conclusion, IL-1α -899C/T, IL-6 -572C/G and IL-18 -607C/A might be risk factors for cerebral infarction development. Further studies with well-designed and large sample size are still required.

Interleukin-18 gene promoter 607A polymorphism, but not 137C polymorphism, is a protective factor for ischemic stroke in the Chinese population: A meta-analysis

Some epidemiological studies have evaluated the association between interleukin (IL)-18 promoter polymorphisms and the risk of ischemic stroke (IS), but the results were inconsistent. The present meta-analysis was therefore performed to investigate the relationship between IL-18 promoter 137G/C and 607C/A polymorphisms and the risk of IS in the Chinese population. Related studies from PubMed, Embase, Web of Science, CBMdisc and CNKI databases up to November 1, 2014 were systematically searched, also the reference lists of identified articles were manually searched. Information was extracted to calculate for the allelic, genotypic, dominant and recessive models using the pooled odds ratios (ORs) along with 95% confidence intervals (CIs). Evidence of significant association between 607C/A polymorphism and risk of IS was found in four genetic models based on the overall population. However, no significant association between 137G/C polymorphism and risk of IS was found in four genetic models. In summary, the present study suggests that IL-18 gene promoter 607A polymorphism is a protective factor for IS in the Chinese population, while 137C polymorphism has weaker or no protective properties. Still, a larger number of studies with large scale and sufficient original information are required to further confirm our findings.

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We performed a meta-analysis to investigate the relationship between IL-18 gene promoter polymorphisms and ischemic stroke.

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IL-18 gene promoter 607C/A polymorphism is a protective factor for ischemic stroke in the Chinese population.

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This is the first meta-analysis studying such association in Chinese ischemic stroke patients.

Increased IL18 mRNA levels in peripheral artery disease and its association with triglyceride and LDL cholesterol levels: a pilot study

Peripheral artery disease (PAD) typically refers to lower limb vessel ischemia caused by atherosclerotic stenosis of lower extremity arteries. IL18 is a pleiotropic pro-inflammatory cytokine reported to function as an inflammatory biomarker in cardiovascular diseases. IL18 activity is balanced by high-affinity naturally occurring IL18-binding protein (IL18BP). This study aimed to determine whether IL18, IL18 BP mRNA levels and -137 G/C (rs187238) polymorphism, which was previously associated with IL18 gene transcriptional activity, were associated with PAD etiology. IL18, IL18BP mRNA levels from peripheral blood mononuclear cells and -137 G/C (rs187238) polymorphism were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and RT-PCR, respectively, in 55 PAD patients (26 aorta-iliac, 29 femoro-popliteal) and 61 disease-free controls. IL18 mRNA levels were increased in PAD patients compared with healthy controls (p = 0.09); however, did not reach a statistical significant level, also did not significantly differ between aorta-iliac and femoro-popliteal occlusive PAD subgroups (p = 0.285). However, IL18BP mRNA levels were significantly lower in PAD group compared with controls (p < 0.001). Genotype frequencies of rs187238 polymorphism did not significantly differ between PAD patients and controls (p = 0.385). IL18 mRNA levels were significantly correlated with triglycerides and LDL cholesterol levels in PAD patients (p = 0.003, p = 0.014, respectively). HDL cholesterol levels were negatively correlated with IL18 mRNA levels in controls (p = 0.05). This report is a preliminary study to show an association between IL18, IL18BP mRNA levels and PAD and suggests that the IL18 gene may have a significant relationship with triglyceride and LDL cholesterol levels in PAD patients.

Investigation on the IL-18 -607A/C and -137C/G on the susceptibility of ischemic stroke

OBJECTIVE

We conducted a case-control study with 322 cases and 322 controls to assess the role of the two common SNPs in the promoter of IL-18 gene.

METHODS

Polymerase chain reaction restriction fragment length of polymorphism (PCR-RFLP) was taken to genotype -607A/C and -137C/G in the promoter of the IL-18 gene.

RESULTS

By comparing cases and control subjects, we found that IS cases were more likely to have higher BMI, higher proportion of hypertension, and have higher proportion of smokers and drinkers. We found that IL-18 -607CC genotype (OR=1.70, 95% CI=1.03-2.81) and C allele (OR=1.26, 95% CI=1.01-1.58) were significantly more frequent in IS patients when compared with AA genotype. We did not find significant association between IL-18 -607A/C gene polymorphism and BMI, hypertension, smoking and drinking on the risk of IS.

CONCLUSION

Our study suggests that polymorphisms in IL-18 -607A/C can influence the development of IS, and this gene polymorphism is associated with risk of IS in a Chinese population.

Donor IL-18 rs5744247 polymorphism as a new biomarker of tacrolimus elimination in Chinese liver transplant patients during the early post-transplantation period: results from two cohort studies

Aim: This study evaluated the relationships between IL-18 polymorphisms and tacrolimus elimination in Chinese liver transplant patients. Patients & methods: Eighty-four liver transplant patients from Shanghai (training set) and 50 patients from Shandong (validating set) were inculded. IL-18 polymorphisms (rs5744247, rs7106524, rs549908, rs187238 and rs1946518) and CYP3A5 rs776746 were genotyped. Results: In training set, daily drug dose, total bilirubin, donor CYP3A5 rs776746 and IL-18 rs5744247 genotypes were screened to construct prediction model for tacrolimus elimination. This model was confirmed in validating set (p < 0.001). Donor IL-18 rs5744247 polymorphism was an independent predictor of tacrolimus elimination in the first week after transplantation in both training (p = 0.008) and validating cohorts (p = 0.033). Conclusion: Donor IL-18 rs5744247 polymorphism may influence on tacrolimus elimination.

Original submitted 16 July 2014; Revision submitted 12 November 2014

Association between interleukin-18 promoter variants and tacrolimus pharmacokinetics in Chinese renal transplant patients

PURPOSE

Interleukin 18 (IL-18) is a potent proinflammatory cytokine thought to down-regulate cytochrome P450 (CYP) enzyme activities. This study aimed to assess the potential influence of two functional single nucleotide polymorphisms (SNPs) in the IL-18 promoter region on the tacrolimus pharmacokinetics in Chinese renal transplant patients.

METHODS

We enrolled 96 renal allograft recipients receiving tacrolimus-based immunosuppressive regiments. Two functional SNPs in the IL-18 gene promoter region at the positions -137G/C (rs187283) and -607A/C (rs1946518) and one SNP (rs776746) of CYP3A5 were genotyped using a Mass ARRAY platform. Tacrolimus daily doses (mg/day) and trough tacrolimus concentration (ng/ml) were continuously recorded for 1 month after transplantation.

RESULTS

The tacrolimus C/D ratio was significantly associated with the IL-18 rs1946518 gene polymorphism in the first month after transplantation (P = 0.0225). We studied the influence of its polymorphism on tacrolimus C/D ratios in subjects with different CYP3A5 genotype backgrounds, and among patients with CYP3A5 expressers, the difference among the three genotypes was even more striking (P < 0.001). We did not find significant differences in tacrolimus C/D ratios between the IL-18 rs187238 genotypes, either nominally or according to the CYP3A5 genotype. In a simple linear regression model, age, hemoglobin (Hb), CYP3A5 gene polymorphisms, and IL-18 A-607C gene polymorphisms were associated with log-transformed tacrolimus C/D ratios (P < 0.05). In the final multiple linear regression model, CYP3A5 polymorphisms were the most important variant, accounting for 19.5 % of total variation involved in tacrolimus pharmacokinetics.

CONCLUSION

Our findings suggest that a combined analysis of CYP3A5 and IL-18 promoter polymorphisms may help clinicians develop individualized tacrolimus treatment, which is based on determining CYP3A5 genotype.

Correlation between interleukin-18 promoter -607C/A polymorphism and susceptibility to ischemic stroke

Single nucleotide polymorphisms in the promoter region of interleukin-18 (IL-18), an inflammatory cytokine, have been linked to susceptibility to many diseases, including cancer and immune dysfunction. Here, we explored the potential association between the IL-18 -607C/A (rs1946518) promoter region polymorphism and susceptibility to ischemic stroke (IS). This locus was amplified from peripheral blood samples of 386 IS patients (cases) and 364 healthy individuals (controls) by the polymerase chain reaction with sequence-specific primers. Significant differences were observed by the χ² test in the -607C/A (rs1946518) genotype and allele frequencies between cases and controls (P < 0.05). Furthermore, after excluding for age, gender, smoking status, and hypertension, logistic regression indicated that IS susceptibility of -607C carriers increased 1.6 times (OR = 1.601, 95%CI = 1.148-2.233, P = 0.006) compared to -607A carriers. Additionally, similar increases in IS risk were noted for male patients or patients less than 65 years old. In conclusion, IL-18 -607C/A (rs1946518) promoter polymorphism is associated with IS susceptibility, and the C allele may confer increased IS risk.