Association of interleukin-6 gene polymorphism with coronary artery disease: an updated systematic review and cumulative meta-analysis

Association of E-Selectin gene polymorphisms and serum E-Selectin level with risk of coronary artery disease in lur population of Iran

BACKGROUND

Adhesion molecules like E-selectin have important role in pathogenesis of atherosclerosis. C1901T and G98T polymorphisms of E-selectin gene and E-selectin serum level may affect the risk of coronary artery disease (CAD).

METHODS

A total of 145 normal individuals and 154 patients diagnosed with CAD from the Lur population of Iran undergoing coronary angiography were enrolled. Genetic polymorphisms of E-selectin were determined using PCR-RFLP. Serum level of soluble E-selectin was measured using Elisa.

RESULTS

T allele in C1901T polymorphism was significantly associated with an increased risk of atherosclerosis (P = 0.018). No significant association was observed for G98T polymorphism. The mean serum level of soluble E-selectin in the patient group was significantly higher than the control group (P < 0.001).

CONCLUSIONS

Allele type in C1901T polymorphism plays a role in increasing the risk of developing CAD. Furthermore, since serum E-selectin level is associated with systemic inflammation, it contributes to the increased risk of the disease.

Study of the rs1800795 polymorphism of the <i>IL6</i> gene to verify the clinical portrait of a patient with chronic heart failure: gender aspects

Background. Genetic studies in cardiology allow to identify predisposition and predict the course of multifactorial cardiovascular diseases by identifying the association of polymorphic loci of candidate genes with the clinical phenotype. One of these diseases associated with poor prognosis is chronic heart failure (CHF). Activation of pro-inflammatory cytokines is one of the key aspects of the development and progression of CHF. Aim. To identify the features of the clinical course of CHF of ischemic etiology in patients, taking into account the gender and genotype of the rs1800795 polymorphism of the IL6 gene. Materials and methods. Four hundred fourteen patients of both sexes with stable CHF of ischemic origin, aged 66.410.4 years, were included. Clinical characteristics of men and women of each genotype of the rs1800795 polymorphism of the IL6 gene were compared. Genotyping of the rs1800795 polymorphism of the IL6 gene was performed by real-time polymerase chain reaction. Results. In male patients with CHF, the frequency of allele C was higher than in the control group (p=0.04). Homozygous carriers of the C allele showed a greater risk of developing atrial fibrillation (p=0.021). In terms of biochemical parameters, in patients with a heterozygous genotype, compared with homozygotes for the G allele of the rs1800795 polymorphism of the IL6 gene, the levels of cholesterol, triglycerides (TG), cholesterol not associated with high-density lipoproteins (non-HDL-cholesterol) were higher (p=0.044, p=0.019, p=0.016). Patients with the CC genotype of the rs1800795 polymorphism of the IL6 gene females compared with men were more likely to have IIIIV functional class of CHF (p=0.001) and had a high heart rate (p=0.021). Male patients of the CG genotype were more likely to undergo coronary interventions (p=0.001). In women of the CG genotype, CHF was more often combined with DM (p=0.015), the level of non-HDL-cholesterol (p=0.04) was higher, and glomerular filtration rate was lower than in men (p=0.001). Comparison of the GG genotype revealed a higher incidence of chronic kidney disease in women (p=0.022). Women had significantly lower glomerular filtration rate (p=0.001), systolic blood pressure (p=0.004). The level of such biochemical parameters as cholesterol (p=0.001), TG (p=0.019), low-density lipoprotein cholesterol (p=0.002) was reduced, except for high non-HDL-cholesterol (p=0.001). There were more men with left ventricular ejection fraction 40% (p=0.009), women with left ventricular ejection fraction 50% (p=0.002). Conclusion. The identified phenotypic and gender differences create prerequisites for determining patient-oriented genetic risk, opening up new opportunities for preventing the progression and complications of CHF.

DNA methylation changes and inflammaging in aging-associated diseases

Aging as an inevitable phenomenon is associated with pervasive changes in physiological functions. There is a relationship between aging and the increase of several chronic diseases. Most age-related disorders are accompanied by an underlying chronic inflammatory state, as demonstrated by local infiltration of inflammatory cells and greater levels of proinflammatory cytokines in the bloodstream. Within inflammaging, many epigenetic events, especially DNA methylation, change. During the aging process, due to aberrations of DNA methylation, biological processes are disrupted, leading to the emergence or progression of a variety of human diseases, including cancer, neurodegenerative disorders, cardiovascular disease and diabetes. The focus of this review is on DNA methylation, which is involved in inflammaging-related activities, and how its dysregulation leads to human disorders.

Interleukin-6 cytokine: An overview of the immune regulation, immune dysregulation, and therapeutic approach

Several studies have shown that interleukin 6 (IL-6) is a multifunctional cytokine with both pro-inflammatory and anti-inflammatory activity, depending on the immune response context. Macrophages are among several cells that secrete IL-6, which they express upon activation by antigens, subsequently inducing fever and production of acute-phase proteins from the liver. Moreover, IL-6 induces the final maturation of B cells into memory B cells and plasma cells as well as an adaptive role for short-term energy allocation. Activation of IL-6 receptors results in the intracellular activation of the JAK/STAT pathway with resultant production of inflammatory cytokines. Several mechanisms-controlled IL-6 expression, but aberrant production was shown to be crucial in the pathogenesis of many diseases, which include autoimmune and chronic inflammatory diseases. IL-6 in combination with transforming growth factor β (TGF-β) induced differentiation of naïve T cells to Th17 cells, which is the cornerstone in autoimmune diseases. Recently, IL-6 secretion was shown to form the backbone of hypercytokinemia seen in the Coronavirus disease 2019 (COVID-19)-associated hyperinflammation and multiorgan failure. There are two classes of approved IL-6 inhibitors: anti-IL-6 receptor monoclonal antibodies (e.g., tocilizumab) and anti-IL-6 monoclonal antibodies (i.e., siltuximab). These drugs have been evaluated in patients with rheumatoid arthritis, juvenile idiopathic arthritis, cytokine release syndrome, and COVID-19 who have systemic inflammation. JAK/STAT pathway blockers were also successfully used in dampening IL-6 signal transduction. A better understanding of different mechanisms that modulate IL-6 expression will provide the much-needed solution with excellent safety and efficacy profiles for the treatment of autoimmune and inflammatory diseases in which IL-6 derives their pathogenesis.

The Role of Plasma Interleukin-6 Levels on Atherosclerotic Cardiovascular Disease and Cardiovascular Mortality Risk Scores in Javanese Patients with Chronic Kidney Disease

Interleukin-6 (IL-6) has been identified as an important pro-inflammatory factor involved in mediating the severity of chronic kidney disease (CKD). This study sought to determine the effect of plasma IL-6 levels on atherosclerotic cardiovascular disease (ASCVD) and cardiovascular mortality risk scores in Javanese CKD patients. We also analyzed the frequency of IL-6 G174C single nucleotide polymorphism (SNP) in the population. This study was a cross-sectional study involving seventy-three patients of Javanese ethnic origin with stable chronic kidney disease. We assessed the ASCVD risk score, cardiovascular mortality score, genotyping of IL-6 G174C SNP, and plasma IL-6 levels in these patients. The genotype distribution and allele frequencies of the IL-6 G174C SNP were predominated by the G genotype/allele (GG: 97.26%, GC: 1.37%, CC: 1.37%, G-allele: 97.95%, and C-allele: 2.05%). Despite the fact that plasma IL-6 levels did not directly affect cardiovascular mortality risk, further analysis revealed its direct effect on the ASCVD risk score (path coefficient = 0.184, p = 0.043, 95% CI = 0.018−0.380), which in turn affected cardiovascular mortality risk (path coefficient = 0.851, p = <0.01, 95% CI = 0.714−0.925). In conclusion, plasma IL-6 levels play important roles on ASCVD risk and cardiovascular mortality risk in Javanese patients with CKD.

IL-6 Revisited: From Rheumatoid Arthritis to CAR T Cell Therapy and COVID-19

The diverse biological activity of interleukin-6 (IL-6) contributes to the maintenance of homeostasis. Emergent infection or tissue injury induces rapid production of IL-6 and activates host defense through augmentation of acute-phase proteins and immune responses. However, excessive IL-6 production and uncontrolled IL-6 receptor signaling are critical to pathogenesis. Over the years, therapeutic agents targeting IL-6 signaling, such as tocilizumab, a humanized anti-IL-6 receptor antibody, have shown remarkable efficacy for rheumatoid arthritis, Castleman disease, and juvenile idiopathic arthritis, and their efficacy in other diseases is continually being reported. Emerging evidence has demonstrated the benefit of tocilizumab for several types of acute inflammatory diseases, including cytokine storms induced by chimeric antigen receptor T-cell therapy and coronavirus disease 2019 (COVID-19). Here, we refocus attention on the biology of IL-6 and summarize the distinct pathological roles of IL-6 signaling in several acute and chronic inflammatory diseases. Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Exploring New Kingdoms: The Role of Extracellular Vesicles in Oxi-Inflamm-Aging Related to Cardiorenal Syndrome

The incidence of age associated chronic diseases has increased in recent years. Although several diverse causes produce these phenomena, abundant evidence shows that oxidative stress plays a central role. In recent years, numerous studies have focused on elucidating the role of oxidative stress in the development and progression of both aging and chronic diseases, opening the door to the discovery of new underlying mechanisms and signaling pathways. Among them, senolytics and senomorphics, and extracellular vesicles offer new therapeutic strategies to slow the development of aging and its associated chronic diseases by decreasing oxidative stress. In this review, we aim to discuss the role of extracellular vesicles in human cardiorenal syndrome development and their possible role as biomarkers, targets, or vehicles of drugs to treat this syndrome.

Association of interleukin 6 -174 G/C polymorphism with coronary artery disease and circulating IL-6 levels: a systematic review and meta-analysis

INTRODUCTION

Circulating IL-6 levels and at least one polymorphic form of IL6 gene (IL6 -174 G/C, rs1800795) have been shown to be independently associated with coronary artery disease (CAD) by several investigators. Despite more than 12 published meta-analyses on this subject, association of -174 G/C with CAD, especially amongst distinct ancestral population groups remain unclear. We, therefore, conducted a systematic review and an updated meta-analysis to comprehensively ascertain the association of IL6 -174 G/C with CAD and circulating IL-6 levels.

MATERIALS AND METHODS

Relevant case-control/cohort studies investigating association of -174 G/C with CAD and circulating IL-6 levels were identified following a comprehensive online search. Association status for CAD was determined for the pooled sample, as well as separately for major ancestral subgroups. Association status for circulating IL-6 levels was assessed for the pooled sample, as well as separately for CAD cases and CAD free controls. Study-level odds ratios (OR) and 95% confidence intervals (CI) were pooled using random/fixed-effects model.

RESULTS

Quantitative synthesis for the CAD endpoint was performed using 55 separate qualifying studies with a collective sample size of 51,213 (19,160 cases/32,053 controls). Pooled association of -174 G/C with CAD was found to be statistically significant through dominant (OR 1.15; 95% CI 1.05-1.25, p = 0.002) as well as allelic genetic model comparisons (OR 1.13, 95% CI 1.06-1.21, p = 0.0003). This effect was largely driven by Asian and Asian Indian ancestral subgroups, which also showed significant association with CAD in both genetic model comparisons (OR range 1.29-1.53, p value range ≤ 0.02). Other ancestral subgroups failed to show any meaningful association. Circulating IL-6 levels were found to be significantly higher amongst the 'C' allele carriers in the pooled sample (Standard mean difference, SMD 0.11, 95% CI 0.01-0.22 pg/ml, p = 0.009) as well as in the CAD free control subgroup (SMD 0.10, 95% CI 0.02-0.17 pg/ml, p = 0.009), though not in the CAD case subgroup (SMD 0.17, 95% CI = - 0.02 to 0.37, p = 0.12).

CONCLUSIONS

The present systematic review and meta-analysis demonstrate an overall association between IL6 -174 G/C polymorphism and CAD, which seems to be mainly driven by Asian and Asian Indian ancestral subgroups. Upregulation of plasma IL-6 levels in the 'C' allele carriers seems to be at least partly responsible for this observed association. This warrants further investigations with large, structured case-control studies especially amongst Asian and Asian Indian ancestral groups.

IL-6 in inflammation, autoimmunity and cancer

IL-6 is involved both in immune responses and in inflammation, hematopoiesis, bone metabolism and embryonic development. IL-6 plays roles in chronic inflammation (closely related to chronic inflammatory diseases, autoimmune diseases and cancer) and even in the cytokine storm of corona virus disease 2019 (COVID-19). Acute inflammation during the immune response and wound healing is a well-controlled response, whereas chronic inflammation and the cytokine storm are uncontrolled inflammatory responses. Non-immune and immune cells, cytokines such as IL-1β, IL-6 and tumor necrosis factor alpha (TNFα) and transcription factors nuclear factor-kappa B (NF-κB) and signal transducer and activator of transcription 3 (STAT3) play central roles in inflammation. Synergistic interactions between NF-κB and STAT3 induce the hyper-activation of NF-κB followed by the production of various inflammatory cytokines. Because IL-6 is an NF-κB target, simultaneous activation of NF-κB and STAT3 in non-immune cells triggers a positive feedback loop of NF-κB activation by the IL-6-STAT3 axis. This positive feedback loop is called the IL-6 amplifier (IL-6 Amp) and is a key player in the local initiation model, which states that local initiators, such as senescence, obesity, stressors, infection, injury and smoking, trigger diseases by promoting interactions between non-immune cells and immune cells. This model counters dogma that holds that autoimmunity and oncogenesis are triggered by the breakdown of tissue-specific immune tolerance and oncogenic mutations, respectively. The IL-6 Amp is activated by a variety of local initiators, demonstrating that the IL-6-STAT3 axis is a critical target for treating diseases.

Bioinformatics analysis identifies potential diagnostic signatures for coronary artery disease

Background

Coronary artery disease (CAD) is the leading cause of mortality worldwide. We aimed to screen out potential gene signatures and construct a diagnostic model for CAD.

Method

We downloaded two mRNA profiles, GSE66360 and GSE60993, and performed analyses of differential expression, gene ontology terms, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The STRING database was used to identify protein–protein interactions (PPI). PPI network visualization and screening out of key genes were performed using Cytoscape software. Finally, a diagnostic model was constructed.

Results

A total of 2127 differentially expressed genes (DEGs) were identified in GSE66360, and 527 DEGs in GSE60993. Of the 153 DEGs from both datasets that showed differential expression between CAD patients and controls, 471 biological process terms, 35 cellular component terms, 17 molecular function terms, and 49 KEGG pathways were significantly enriched. The top 20 key genes in the PPI network were identified, and a diagnostic model constructed from five optimal genes that could efficiently separate CAD patients from controls.

Conclusion

We identified several potential biomarkers for CAD and built a logistic regression model that will provide a valuable reference for future clinical diagnoses and guide therapeutic strategies.

Interleukin-6 level is a powerful predictor of long-term cardiovascular mortality in patients with acute coronary syndrome

BACKGROUND

The interleukin-6 (IL-6) pathway has a crucial role in the pathogenesis of atherosclerosis, the main cause of cardiovascular diseases. We aimed to characterize the predictive value of inflammatory biomarkers on long-term cardiovascular mortality in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

METHODS

This prospective observational study included 322 consecutive patients with ACS undergoing PCI. Blood-derived biomarkers IL-6 and high-sensitivity C-reactive protein (hsCRP) were assessed at the time point of ACS. Patients were followed-up for 6 years. Long-term cardiovascular mortality was our primary endpoint. Adjusted Cox-regression analysis was used for prediction of events.

RESULTS

Elevated IL-6 values (≥3.3 pg/mL) emerged as an independent and the most powerful predictor for cardiovascular mortality: the ROC analysis showed that IL-6 was more accurate for cardiovascular mortality prediction as compared to hsCRP (IL-6: AUC = 0.72; 95%CI: 0.62-0.81; p = 0.009 vs hsCRP: AUC = 0.56; 95%CI: 0.41-0.72; p = 0.445). The positive predictive value of IL-6 for mortality was 9%, the negative predictive value 99%, sensitivity 94% and specificity 48%. The primary endpoint of long-term cardiovascular death occurred more frequently in patients with high vs low IL-6 (9.0% vs 0.5%, p = 0.001). The multivariate Cox regression analysis revealed that patients with high IL-6 (≥3.3 pg/mL) values were at 8.6-fold higher hazard to die than those with low IL-6 (<3.3 pg/mL) levels (adj. hazard ratio [HR] = 8.60, 95%CI: 1.07-69.32; p = 0.043).

CONCLUSION

In the setting of ACS, high IL-6 values are associated with substantial long-term cardiovascular mortality. Further, IL-6 performs as a superior predictor for cardiovascular death as compared to hsCRP.

Systematic review and meta-analysis of association of polymorphisms in inflammatory cytokine genes with coronary artery disease

BACKGROUND

It has comprehensively been acknowledged that a genetic contribution, especially in immune inflammatory players, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α, are critically involved in the pathophysiology of coronary artery disease (CAD). This meta-analysis study aimed to reach a conclusive understanding of the role of genetic polymorphisms, including IL6 gene C572G (rs1800796) and G174C (rs1800795) as well as TNFA gene G238A (rs361525) and G308A (rs1800629) in susceptibility to CAD.

METHODS

Two major databases, namely MEDLINE and Scopus, were searched to find the studies surveying the mentioned polymorphisms and CAD susceptibility up to July 2020. Association comparison between the polymorphisms and CAD susceptibility were assessed using pooled odds ratio (OR) and their corresponding 95% confidence interval (CI).

RESULTS

This meta-analysis study was conducted on 69 papers (73 population studies), comprising 5062 patients and 8446 controls for IL6 gene rs1800796 (17 studies), 13801 patients and 16215 controls for IL6 gene rs1800795 (38 studies), 1439 patients and 2850 controls for TNFA gene rs361525 (5 studies), and 5051 patients and 3958 controls for TNFA gene rs1800629 (13 studies), according to inclusion and exclusion criteria. There were statistically positive association between all genetic comparisons of IL6 gene rs1800795 polymorphism and the CAD risk. Moreover, the recessive model (CC vs. CG + GG) in IL6 gene rs1800796 polymorphism had marginally significant association with decreased risk of CAD. None of the TNFA gene polymorphisms were associated with CAD risk.

CONCLUSIONS

The meta-analysis revealed the positive association of IL6 gene rs1800795 polymorphism in susceptibility to CAD.

Associations between IL-6 Variations and Congenital Heart Disease Incidence among Chinese Han People

Background

Our research explored if Interleukin-6 (IL-6) variants held substantial connection to congenital heart disease (CHD) susceptibility among Chinese Han children.

Material/Methods

A total of 102 CHD children were recruited as the case group while 98 healthy persons were recruited as the control group. We used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) completed genotyping for IL-6 variants rs1800795 and rs1800796. The Hardy-Weinberg equilibrium (HWE) among controls was tested using χ² analysis. Genotype and allele frequencies for variants were compared between groups. Odds ratio (OR) accompanied by 95% confidence interval (CI) reflected the potential link of IL-6 variants to CHD occurrence.

Results

A remarkable increased trend of rs1800795 CC genotype and C allele was detected in the CHD patient group (P<0.05). Individuals carrying rs1800795 CC genotype showed higher risk for CHD (OR=3.763, 95% CI=1.162–12.190). In addition, rs1800795 C allele could increase CHD incidence (OR=1.766, 95% CI=1.101–2.832). No significant differences were detected in IL-6 gene rs1800796 polymorphism in both genotype and allele distributions between the case group and the control group (P>0.05). These associations had no significant alteration after the adjustment of age, gender, maternal smoking history, and maternal history of diabetes.

Conclusions

IL-6 variant rs1800795 exhibited a close relation to CHD susceptibility among Chinese Han people while the mutant C allele promoted CHD incidence. But rs1800796 variant showed no such influence.

The IL-6 rs1800795 and rs1800796 polymorphisms are associated with coronary artery disease risk

Studies examining the associations between the interleukin‐6 (IL‐6) rs1800795 and rs1800796 gene polymorphisms and risk of coronary artery disease (CAD) remain controversial. Our aim was to evaluate the accurately determine role of these two polymorphisms in CAD risk. PubMed, Embase, VIP, Wan fang and China National Knowledge Infrastructure databases were searched. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The trial sequential analysis (TSA) was conducted, and bioinformatics tools were employed. A total of thirty‐seven articles were obtained. For the IL‐6 rs1800795 polymorphism, 9411 CAD patients and 3161 controls were included, 4720 patients with CAD, and 5000 controls were included for the IL‐6 rs1800796 polymorphism. In the pooled analysis, significant associations were only observed for the rs1800796 polymorphism (allelic: OR [95%CI] = 1.28 [1.13, 1.44], dominant: OR [95%CI] = 1.35 [1.17, 1.57], recessive: OR [95%CI] = 1.35 [1.18, 1.55], heterozygote: OR [95%CI] = 1.26 [1.15, 1.37], homozygote: OR [95%CI] = 1.62 [1.23, 2.13]). Significant associations were detected in the Asian and Mongoloid populations and ‘more than 500’ subgroup for the rs1800795 polymorphism. TSA confirmed the true‐positive results for the rs1800796 polymorphism. The bioinformatics analysis showed that the two polymorphisms played important roles in the gene transcription. The IL‐6 rs1800796 polymorphism is associated with an increased susceptibility to CAD and is a risk factor for CAD. The IL‐6 rs1800795 polymorphism is associated with an increased risk of CAD in Asians, particularly in Chinese, and a decreased risk of CAD in an African population is remarkably observed.

Risk Factors for Frailty and Cardiovascular Diseases: Are They the Same?

Cardiovascular disease burden increases with the increasing age of populations. Also, with increasing longevity, some individuals are ageing along an unfavourable path developing frailty syndrome. Epidemiologic studies indicate that frailty is overrepresented among the persons with cardiovascular disease. On the other hand, frail subjects tend to be burdened with cardiovascular disease to a greater degree than their biologically better-off peers. Hypertension, diabetes, and obesity, especially abdominal, and at least some other risk factors appear to be shared between frailty and cardiovascular disease. The probable common underlying pathophysiologic feature is inflammation and associated phenomena, possibly having its root in the inflammageing. We discuss these issues based on the results of original studies, comprehensive literature reviews, and metaanalyses, by hundreds of dedicated researchers worldwide.

Inflammatory and cardiovascular diseases biomarkers in chronic hepatitis C virus infection: A review

Hepatitis C virus (HCV) infects 180 million people worldwide and over 4 million people in the United States. HCV infection is a major cause of chronic liver disease and is recognized as a risk factor for clinical cardiovascular disease (CVD). Many studies have shown increased prevalence of cardiac and inflammatory biomarkers in patients with chronic HCV infection (CHC), and though these markers may be used to risk stratify people for cardiac disease in the general population their role in the HCV population is unknown. Patients with CHC have elevated cardiac and inflammatory biomarkers compared to noninfected controls which may play a role in CVD risk stratification. We undertook a systematic review of inflammatory and cardiac biomarkers in people with HCV infection with a focus on the effect of CHC on serum levels of these markers and their utility as predictors of CVD in this population. Medline, EMBASE, and Cochrane databases were searched for relevant articles until June 2019. A total of 2430 results were reviewed with 115 studies included. Our review revealed that HCV infection significantly alters serum levels of markers of inflammation, endothelial function, and cardiac dysfunction prior to HCV treatment, and some of which may change in response to HCV therapy. Current risk stratification tools for development of CVD in the general population may not account for the increased inflammatory markers that appear to be elevated among HCV‐infected patients contributing to increased CVD risk.

Genetics of Human Longevity Within an Eco-Evolutionary Nature-Nurture Framework

Human longevity is a complex trait, and to disentangle its basis has a great theoretical and practical consequences for biomedicine. The genetics of human longevity is still poorly understood despite several investigations that used different strategies and protocols. Here, we argue that such rather disappointing harvest is largely because of the extraordinary complexity of the longevity phenotype in humans. The capability to reach the extreme decades of human lifespan seems to be the result of an intriguing mixture of gene-environment interactions. Accordingly, the genetics of human longevity is here described as a highly context-dependent phenomenon, within a new integrated, ecological, and evolutionary perspective, and is presented as a dynamic process, both historically and individually. The available literature has been scrutinized within this perspective, paying particular attention to factors (sex, individual biography, family, population ancestry, social structure, economic status, and education, among others) that have been relatively neglected. The strength and limitations of the most powerful and used tools, such as genome-wide association study and whole-genome sequencing, have been discussed, focusing on prominently emerged genes and regions, such as apolipoprotein E, Forkhead box O3, interleukin 6, insulin-like growth factor-1, chromosome 9p21, 5q33.3, and somatic mutations among others. The major results of this approach suggest that (1) the genetics of longevity is highly population specific; (2) small-effect alleles, pleiotropy, and the complex allele timing likely play a major role; (3) genetic risk factors are age specific and need to be integrated in the light of the geroscience perspective; (4) a close relationship between genetics of longevity and genetics of age-related diseases (especially cardiovascular diseases) do exist. Finally, the urgent need of a global approach to the largely unexplored interactions between the 3 genetics of human body, that is, nuclear, mitochondrial, and microbiomes, is stressed. We surmise that the comprehensive approach here presented will help in increasing the above-mentioned harvest.

Association of interleukin-6 polymorphisms with obesity: A systematic review and meta-analysis

Obesity is a common metabolic disorder with increasing trend all around the world. Owing to the role of pro-inflammatory cytokines on obesity, we aimed to investigate the role of interleukin-6 (IL-6) polymorphisms on risk of obesity. Electronic literatures were searched in Web of Science, PubMed, Embase, and Scopus. The references of relevant reviews and included studies were also manually checked. All types of observational studies from 1 January 1992 to 28 February 2018 were included. Odds ratio (OR) was estimated by fixed and random effect model. Subgroup analysis was carried out based on age statues. Pooling analysis of eligible studies have been considered for rs2069845 and rs1800796, and no significant results were observed. Minor allele of IL-6 rs1800797polymorphism decreased the risk of obesity/overweight in allelic 0.74 (0.59-0.92), dominant 0.65 (0.49-0.85), and over-dominant 0.66 (0.51-0.87) models. Fourteen eligible studies were included for rs1800795. According to BMI, C allele showed increased risk of obesity in genetic models containing homozygote model 1.47 (1.02-2.12) for body mass index (BMI) ≥ 25 vs. BMI < 25, recessive model 1.32 (1.07-1.63) for BMI ≥ 30 vs. BMI < 25, and homozygote model 1.35 (1.10-1.66) for BMI ≥ 30 vs. BMI < 30. In overall definition of obesity more significant results were observed, including homozygote model in obese vs. normal 1.71 (1.14-2.56). Similarly, subgroups analysis revealed additional significant results. Minor alleles of rs1800795 raised and rs1800797 reduced the risk of obesity, while rs1800796 and rs2069845 may not be associated. However, more observational studies are recommended to confirm these results.

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.

Association of genetic polymorphisms with acute kidney injury after cardiac surgery in a Southeast Asian population

Introduction

Genetic polymorphisms are important in explaining the wide interpatient variability that exists in the development of acute kidney injury (AKI) post cardiac surgery. We hypothesised that polymorphisms in 4 candidate genes, namely angiotensin-converting enzyme (ACE), apolipoprotein-E (ApoE), interleukin-6 (IL-6), and tumour necrosis factor-alpha (TNF-α) are associated with AKI.

Methods

870 patients who underwent cardiac surgery in Singapore were analysed. All patients who fulfilled stage 1 KDIGO criteria and above were considered to have AKI. This was investigated against various demographic, clinical and genetic factors.

Results

Increased age, history of hypertension, anaemia and renal impairment remained important preoperative risk factors for AKI. Intraoperatively, longer cardiopulmonary bypass (CPB) time and the use of intra-aortic balloon pump (IABP) were shown to be associated with AKI. Among the genetic factors, ACE-D allele was associated with an increased risk of AKI while IL6-572C allele was associated with a decreased risk of AKI.

Conclusion

ACE-D allele was associated with the development of AKI similar to other studies. On the other hand, IL6-572C was shown to have a protective role against the development of AKI, contradictory to studies done in the Caucasian population. This contradictory effect of IL6-572C is a result of a complex interplay between the gene and population specific modulating factors. Our findings further underscored the necessity of taking into account population specific differences when developing prediction models for AKI.

Genetic Polymorphisms in Sepsis and Cardiovascular Disease: Do Similar Risk Genes Suggest Similar Drug Targets?

Genetic variants are associated with altered clinical outcome of patients with sepsis and cardiovascular diseases. Common gene signaling pathways may be involved in the pathophysiology of these diseases. A better understanding of genetic commonality among these diseases may enable the discovery of important genes, signaling pathways, and therapeutic targets for these diseases. We investigated the common genetic factors by a systematic search of the literature. Twenty-four genes (ADRB2, CD14, FGB, FV, HMOX1, IL1B, IL1RN, IL6, IL10, IL17A, IRAK1, MASP2, MBL, MIR608, MIF, NOD2, PCSK9, PPARG, PROC, SERPINE1, SOD2, SVEP1, TF, TIRAP, TLR1) were extracted as reported genetic variations associated with altered outcome of both sepsis and cardiovascular diseases. Of these genes, the adverse allele (or combinations) was same in nine (ADRB2, FV, HMOX1, IL6, MBL, MIF, NOD2, PCSK9, SERPINE1), and the effect appears to be in the same direction in both sepsis and cardiovascular disease. Shared gene signaling pathways suggest that these are true biological results and could point to overlapping drug targets in sepsis and cardiovascular disease.

Inflammation-Accelerated Senescence and the Cardiovascular System: Mechanisms and Perspectives

Low-grade chronic inflammation is a common denominator in atherogenesis and related diseases. Solid evidence supports the occurrence of an impairment in the innate and adaptive immune system with senescence, favoring the development of acute and chronic age-related diseases. Cardiovascular (CV) diseases (CVD), in particular, are a leading cause of death even at older ages. Inflammation-associated mechanisms that contribute to CVD development include dysregulated redox and metabolic pathways, genetic modifications, and infections/dysbiosis. In this review, we will recapitulate the determinants and consequences of the immune system dysfunction at older age, with particular focus on the CV system. We will examine the currently available and potential future strategies to counteract accelerated CV aging, i.e., nutraceuticals, probiotics, caloric restriction, physical activity, smoking and alcohol cessation, control of low-grade inflammation sources, senolytic and senescence-modulating drugs, and DNA-targeting drugs.

The Two-Faced Cytokine IL-6 in Host Defense and Diseases

Interleukein-6 (IL-6), is produced locally from infectious or injured lesions and is delivered to the whole body via the blood stream, promptly activating the host defense system to perform diverse functions. However, excessive or sustained production of IL-6 is involved in various diseases. In diseases, the IL-6 inhibitory strategy begins with the development of the anti-IL-6 receptor antibody, tocilizumab (TCZ). This antibody has shown remarkable effects on Castleman disease, rheumatoid arthritis and juvenile idiopathic arthritis. In 2017, TCZ was proven to work effectively against giant cell arteritis, Takayasu arteritis and cytokine releasing syndrome, initiating a new era for the treatment of these diseases. In this study, the defensive functions of IL-6 and various pathological conditions are compared. Further, the diseases of which TCZ has been approved for treatment are summarized, the updated results of increasing off-label use of TCZ for various diseases are reviewed and the conditions for which IL-6 inhibition might have a beneficial role are discussed. Given the involvement of IL-6 in many pathologies, the diseases that can be improved by IL-6 inhibition will expand. However, the important role of IL-6 in host defense should always be kept in mind in clinical practice.

An Evidence-Based Meta-Analysis on the Roles of Functional Interleukin-6 Polymorphisms in Coronary Artery Disease

Recently, the relationship between functional interleukin-6 (IL-6) polymorphisms and coronary artery disease (CAD) was extensively studied, with controversial findings. Therefore, we conducted this meta-analysis to better elucidate the relationship between these polymorphisms and the risk of CAD. A total of 57 case-control studies were finally included. The overall analyses showed that IL-6 -174G>C and -572G>C polymorphisms were significantly associated with the risk of CAD, the C allele of -174G>C (G versus C, odds ratio [OR] = 0.82, confidence interval [95% CI] = 0.75-0.89) and -572G>C polymorphisms (G versus C, OR = 0.82, 95% CI = 0.74-0.92) conferred an increased susceptibility to CAD. Further subgroup analyses yielded similar positive results for -174G>C polymorphism in Asian and Caucasian populations, and for -572G>C polymorphism in Asian and African populations. In conclusion, our findings suggest that IL-6 -174G>C and -572G>C polymorphisms may serve as potential genetic markers of CAD.

Inflammageing: chronic inflammation in ageing, cardiovascular disease, and frailty

Most older individuals develop inflammageing, a condition characterized by elevated levels of blood inflammatory markers that carries high susceptibility to chronic morbidity, disability, frailty, and premature death. Potential mechanisms of inflammageing include genetic susceptibility, central obesity, increased gut permeability, changes to microbiota composition, cellular senescence, NLRP3 inflammasome activation, oxidative stress caused by dysfunctional mitochondria, immune cell dysregulation, and chronic infections. Inflammageing is a risk factor for cardiovascular diseases (CVDs), and clinical trials suggest that this association is causal. Inflammageing is also a risk factor for chronic kidney disease, diabetes mellitus, cancer, depression, dementia, and sarcopenia, but whether modulating inflammation beneficially affects the clinical course of non-CVD health problems is controversial. This uncertainty is an important issue to address because older patients with CVD are often affected by multimorbidity and frailty - which affect clinical manifestations, prognosis, and response to treatment - and are associated with inflammation by mechanisms similar to those in CVD. The hypothesis that inflammation affects CVD, multimorbidity, and frailty by inhibiting growth factors, increasing catabolism, and interfering with homeostatic signalling is supported by mechanistic studies but requires confirmation in humans. Whether early modulation of inflammageing prevents or delays the onset of cardiovascular frailty should be tested in clinical trials.

Association of Interleukin-6 Genetic Polymorphisms and Environment Factors Interactions with Coronary Artery Disease in a Chinese Han Population

OBJECTIVES

To investigate the influence of IL-6 single nucleotide polymorphisms (SNPs), additional gene-gene and gene-environment interactions on coronary artery disease (CAD) risk.

METHODS

A total of 751 participants (429 CAD patients and 322 controls) were recruited in this study. Logistic regression analysis was conducted to evaluate the association of IL-6 SNPs with CAD risk and generalized multifactor dimensionality reduction (GMDR) was performed to investigate the best interaction combinations for gene-gene and gene-environment interactions.

RESULTS

CAD risk is significantly higher in carriers of C allele of the rs1800795 polymorphism than those with GG genotype (CC + CG versus GG, adjusted OR (95%CI) = 2.07 (1.56-2.86), p < 0.001). GMDR analysis revealed rs1800795 was significantly interacted with tobacco smoking and alcohol drinking in two-locus model (p < 0.0010). Current smokers with CC or CG of rs1800795 genotype have the highest CAD risk, OR (95%CI) = 3.22 (2.45-3.94) and current drinkers with CC or CG of rs1800795 genotype have the highest CAD risk, OR (95%CI) = 3.17 (2.20-4.24).

CONCLUSION

The C allele of rs1800795 within IL-6 gene promoter, rs1800795-tobacco smoking and rs1800795-alcohol drinking interaction were all associated with increased CAD risk.

Review and meta-analysis of genetic polymorphisms associated with exceptional human longevity

BACKGROUND

Many factors contribute to exceptional longevity, with genetics playing a significant role. However, to date, genetic studies examining exceptional longevity have been inconclusive. This comprehensive review seeks to determine the genetic variants associated with exceptional longevity by undertaking meta-analyses.

METHODS

Meta-analyses of genetic polymorphisms previously associated with exceptional longevity (85+) were undertaken. For each variant, meta-analyses were performed if there were data from at least three independent studies available, including two unpublished additional cohorts.

RESULTS

Five polymorphisms, ACE rs4340, APOE ε2/3/4, FOXO3A rs2802292, KLOTHO KL-VS and IL6 rs1800795 were significantly associated with exceptional longevity, with the pooled effect sizes (odds ratios) ranging from 0.42 (APOE ε4) to 1.45 (FOXO3A males).

CONCLUSION

In general, the observed modest effect sizes of the significant variants suggest many genes of small influence play a role in exceptional longevity, which is consistent with results for other polygenic traits. Our results also suggest that genes related to cardiovascular health may be implicated in exceptional longevity. Future studies should examine the roles of gender and ethnicity and carefully consider study design, including the selection of appropriate controls.

Interleukin-6 gene -572G/C polymorphism and prostate cancer risk

Background

The aim of the present study was to determine whether the interleukin-6 (IL-6) -572G/C polymorphism correlates with prostate cancer.

Methods

According to inclusion and exclusion criteria, the association of the IL-6 -572G/C polymorphism with prostate cancer was searched in databases and analyzed using comprehensive meta-analysis software. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of the associations.

Results

We considered a total of six case-control studies including 2237 patients and 1754 controls and the meta-analysis results showed significant association between the IL-6 -572G/C polymorphism and prostate cancer risk(CC vs GG: OR = 0.49, 95% CI =0.37–0.65;CG vs GG: OR =0.71, 95% CI = 0.58–0.87; the dominant model: OR =0.65, 95% CI = 0.54–0.79;the recessive model: OR =0.70, 95% CI = 0.58–0.85). In stratified analyses by ethnicity, significant associations were found among Asian populations. However, no significant association was found in Caucasian populations.

Conclusion

Our findings demonstrated that the -572G/C polymorphism of the IL-6 gene may be a risk factor for the development of prostate cancer in Asians.

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 inflammatory genes with neuroticism, anxiety and depression in male patients with coronary heart disease]

AIM

To explore the relationship of depression and its endophenotypes (neuroticism and trait anxiety) with inflammatory genes in patients with coronary heart disease (CHD).

MATERIAL AND METHODS

A sample consisted of 78 male CHD patients with depression, 91 CHD patients without depression and 127 healthy men. Polymorphisms of the genes encoding interleukine-4 (IL-4 -589 C/T), interleukine-6 (IL-6 -174 G/C), tumor-necrosis factor alpha (TNF-α -308 G/A) and C-reactive protein (CRP -717A/G) were studied.

RESULTS

There was the association between the IL-6 -174 G/C and depression comorbid to CHD (р=0.01; OR=2.3 CI 95% 1.2-4.3). The frequency of the 'high expression' allele G in this group was higher compared to controls. The association between IL-4 -589 C/T and CHD was found. Compared to the control group, the frequency of the IL-4 -589CC genotype was higher in patients regardless of whether they had symptoms of depression (р=0.007; OR=2.1 CI 95% 1.2-3.4). No association between the TNF-α -308G/A and the CRP -717A/G with depression in CHD was observed. There were no differences between neuroticism and anxiety scores in patients with different IL-4 -589 C/T, IL-6 -174 G/C, TNF-α -308 G/A, CRP -717A/G genotypes.

CONCLUSION

The finding of the association between the IL-6 -174G/C and depression, comorbid to CHD, is in line with literature on a role of IL-6 in the development of depression in patients with CHD.

Genetic association of pro-inflammatory cytokine gene polymorphisms with coronary artery disease (CAD) in a North Indian population

BACKGROUND

Cytokines regulate the expression of inflammatory molecules which destabilize the atheromatic plaques. This study focuses on studying the association of inflammatory cytokine polymorphisms like TNF-α -308 (G/A), TNF-β +252 (A/G), IL-6 -174 (G/C) and IL-6 -597 (G/A), and IFN-ɣ +874 (T/A) with coronary artery disease (CAD) among north Indian patients.

MATERIALS AND METHODS

143 CAD and 137 normal healthy controls were recruited in this study. DNA extraction was carried out by high salting out method. TNF-α -308 (G/A) (rs1800797), TNF-β +252 (A/G) (rs909253), IL-6 -174 (G/C) (rs1800795), IL6 -597 (G/A) (rs1800797), and IFN-ɣ +874 (T/A) (rs2430561) SNPs were genotyped by TaqMan®SNP genotyping assays. Different statistical analyses were performed using SPSS v 22.0 and SNPStats. p≤0.05 was considered significant.

RESULTS

Significant risk association with CAD was found for TNF-α -308 (G/A) "A" allele (OR=5.6, CI 1.8-17.4, p=0.001) and TNF-β +252 (A/G) "G" allele (OR=3.4, CI=1.9-6.0, p<0.001). However, no statistical significance was found for IL-6 -174 (G/C) or IL6 -597 (G/A), with CAD. TNF-α -308 (G/A), and TNF-β +252 (A/G) haplotype "GG" "AG" increased CAD risk significantly (GG haplotype, adjusted OR=2.6, CI 1.4-5.0, p=0.003 and AG haplotype OR=8.5, CI 2.2-33.35, p=0.002) after adjustments for age, sex, TC, TG, HDL, APOB, smoking and diet.

DISCUSSION

The present study found significant risk association for TNF-α -308 (G/A), and TNF-β +252 (A/G) genotypes, alleles and haplotypes, with CAD in a North Indian population.

The role and therapeutic targeting of IL-6 in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is an autoimmune chronic disease with joint and systemic inflammation and it has been found that interleukin-6 (IL-6) plays a key role in RA. Indeed, various clinical studies have proved that the first-in-class IL-6 inhibitor, tocilizumab, a humanized anti-IL-6 receptor monoclonal antibody, showed outstanding efficacy in RA. Areas covered: We review here the role of IL-6 in the inflammatory conditions and how IL-6 contributes to pathogenesis of RA, what induces IL-6 and how IL-6 expression is regulated. Furthermore, clinical studies of tocilizumab for RA are summarized, Expert commentary: We review and discuss the prospects for future applications of IL-6 targeting therapy and new therapeutic strategies targeting IL-6. Finally, we discuss relevant issues with regard to the clinical management of IL-6 blockade in RA.

The -174 G>C Interleukin-6 Gene Polymorphism is Associated with Angiographic Progression of Coronary Artery Disease over a 4-Year Period

BACKGROUND

Inflammation is a key process underlying the clinical course of coronary artery disease (CAD). C-reactive protein (CRP) and interleukin-6 (IL-6) contribute to its pathophysiology and act as biomarkers. We sought to examine whether known single nucleotide polymorphisms (SNPs) impact CAD progression, reflecting increased inflammation.

METHODS

We retrospectively evaluated coronary angiographies of patients with established CAD who were re-investigated for stable/unstable angina after a time interval of >12 months. We defined progression of CAD as the emergence of a new plaque or a ≥20 % increase of a formerly non-significant lesion. We genotyped patients for the 1846 C>T CRP and -174 G>C IL-6 SNPs. The probability of CAD progression among the Mendelian randomization groups was evaluated using the Kaplan-Meier method. Data were analyzed using a Cox model that included relevant clinical factors.

RESULTS

A total of 157 patients were included. The serum levels of CRP and IL-6 differed significantly between genotypes. The genotype frequencies of IL-6 were consistent with Hardy-Weinberg equilibrium, whereas those for CRP were excluded from our conclusions. At 48 months, 83 patients (52.9 %) with the IL-6 C allele versus 74 (47.1 %) with the G allele exhibited CAD progression. Patients with the IL-6 C allele had a 52.8 % probability for progression versus 13.3 % for those with the G allele (p=0.005). The results were confirmed by multivariate analysis; dyslipidemia, family history, and IL-6 SNP emerged as significant factors.

CONCLUSION

Patients with established CAD who carried the -174 C allele of the IL-6 gene demonstrated an increased risk for the progression of coronary plaques over a four-year period. Further studies will be needed to validate these findings.

Elevated serum interleukin-6 is predictive of coronary artery disease in intermediate risk overweight patients referred for coronary angiography

BACKGROUND

Interleukin-6 (IL-6) plays a central role in atherosclerosis and inflammation. It may improve risk prediction in patients at intermediate cardiovascular risk.

OBJECTIVE

To analyze the impact of serum IL-6 in predicting early angiographic coronary artery disease in patients at intermediate cardiovascular risk with chest pain.

METHODS

In a cross-sectional study, patients referred for coronary angiography due to suspected coronary artery disease (CAD) were included. Coronary artery disease was defined as the presence of at least 30% stenosis in one or more coronary artery. Severity of CAD was classified by the anatomic burden score. Performance of serum IL-6 assay was compared with ACC/AHA atherosclerotic cardiovascular disease (ASCVD) risk score and hs-CRP through receiver operating characteristic (ROC) curves.

RESULTS

We have included 48 patients with a mean 10-year ASCVD risk of 10.0 ± 6.8%. The prevalence of CAD was 72.9%. The presence of CAD was associated with higher mean levels of IL-6 (p = 0.025). Patients with CAD had significantly more overweight than subjects without CAD. In 27% of patients, IL-6 was >1.0 pg/mL and 100% of these patients had CAD, while only 64% in those with IL-6 <1.0 pg/mL, corresponding to a positive predictive value of 100% (p = 0.015). The area under the receiver operating characteristic (ROC) curve of IL-6, hs-CRP and ASCVD were respectively 0.72, 0.60 and 0.54. Intermediate risk patients with IL-6 >1.0 pg/mL were further reclassified into ASCVD high risk due to the presence of coronary lesions.

CONCLUSION

In intermediate risk patients referred for coronary angiography, a serum IL-6 level above 1 pg/mL is predictive of significant CAD. IL-6 determination may be useful to reclassify ASCVD intermediate risk patients into higher risk categories.

Regulation of IL-6 in Immunity and Diseases

Interleukin-6 (IL-6) is a prototypical cytokine with functional pleiotropy and plays an important role in host defense. When infections or tissue injuries occur, IL-6 is promptly produced by monocytes and macrophages and contributes to removal of infectious agents and restoration of damaged tissues through activation of immune, hematological, and acute-phase responses. Once stress is removed from the host, IL-6 synthesis ends, but uncontrolled excessive or persistent IL-6 production plays a pathological role in the development of various inflammatory diseases and cancers, indicating that IL-6 is a double-edged sword for the host. Thus, the proper IL-6 expression is very important for host defense and is strictly controlled by chromatin structure, transcriptional regulation, and posttranscriptional modification. Differentiation status of cells, various transcription factors, RNA-binding proteins, and microRNAs are involved in this process. Since it is assumed that dysregulation of any of these regulatory molecules may cause abnormal IL-6 expression in a particular disease, further elucidation of the factors and processes involved in IL-6 expression can be expected to facilitate to clarification of pathogenesis and to identification of novel target molecule(s) for specific diseases.