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

Impact of IL-6 rs1800795 and rs1800796 polymorphisms on clinical outcomes of COVID-19: a study on severity of disease in Turkish population

Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is exacerbated by cytokine storms, leading to severe inflammation. Interleukin-6 (IL-6) plays a critical role in this process, and variations in its promoter may influence disease severity. This study aims to investigate the relationship between IL6 promoter polymorphisms rs1800795 (G > C) and rs1800796 (G > C) and the severity of COVID-19 in the Turkish population. A total of 332 participants were included: 84 control, 80 with mild COVID-19, and 168 with severe COVID-19. IL6 polymorphisms were genotyped using the restriction fragment length polymorphism (RFLP) method. The genotypes rs1800795 GC (OR = 3.00, 95% CI: 1.669-5.398, p < 0.000), CC (OR = 7.44, 95% CI: 2.899-19.131, p < 0.000), and rs1800796 GC (OR = 2.76, 95% CI: 1.603-4.761, p < 0.000), as well as the alleles rs1800795 C (OR = 3.01, p < 0.000) and rs1800796 C (OR = 1.97, p = 0.002), may be associated with the severity of COVID-19. According to the Jonckheere-Terpstra (J-T) test, the most significant trends that vary linearly with disease severity were observed for D-dimer [J-T = 15.896, Effect size = 0.68 (0.61 to 0.76), p < 0.000] and CRP [J-T = 15.389, Effect size = 0.66 (0.59 to 0.73), p < 0.000]. The distribution of clinical parameters across genotype combinations (rs1800796/rs1800795*) showed that GC/GC* and GC/CC* were linked to a higher risk of severe inflammation, clotting, and organ damage. Additionally, it has been determined that the G-C and C-C haplotypes may be associated with increased severity of COVID-19. The rs1800795 and rs1800796 polymorphisms are linked to COVID-19 severity and could help guide future treatment strategies.

An IL-6 promoter variant (-174 G/C) augments IL-6 production and alters skeletal muscle transcription in response to exercise in mice

Interleukin-6 (IL-6) is produced and secreted by skeletal muscle cells during exercise and plays an important role in mediating metabolic responses to exercise. The promoter region of the IL-6 gene contains a common genetic variant (-174 G/C, rs1800795), which may alter responses to exercise training. To isolate the impact of this gene variant on exercise-induced IL-6 expression and skeletal muscle transcription responses following exercise, we generated knock-in mice with a GG or variant CC genotype for the murine homolog of rs1800795. The overall gross metabolic phenotype of resting mice was similar between genotypes; however, following acute treadmill running, the variant CC genotype was associated with a greater increase in skeletal muscle Il6 mRNA and circulating IL-6. Furthermore, we observed that mice with the variant CC genotype exhibited sex-specific differences in skeletal muscle master metabolism regulatory genes and had greater increases in genes controlling mitochondrial biogenesis in skeletal muscle post exercise. However, there was no effect of genotype on exercise-induced skeletal muscle glycogen depletion, circulating free fatty acids, blood glucose and lactate production, or exercise-responsive gene expression in subcutaneous fat. These findings suggest that the IL-6 promoter variant -174 G/C may result in enhanced skeletal muscle adaptations in response to exercise training and could mean that individuals with the "C" allele may more readily gain improvements in metabolic health in response to exercise training.NEW & NOTEWORTHY Interleukin-6 (IL-6) is produced and secreted by skeletal muscle during exercise and mediates metabolic responses to exercise. A common variant in the IL-6 promoter region (-174G/C) may alter responses to exercise training. Mice with the variant "CC" genotype exhibited higher skeletal muscle IL-6 mRNA and circulating IL-6 levels post exercise, as well as altered skeletal muscle gene transcription. This suggests that this variant might enhance muscle adaptations to exercise, potentially benefiting metabolic health.

IL-6-174 G/C transversion might decrease male infertility risk: A case-control study

Background

Genetic predispositions have been identified as important factors in male infertility. Among the many genes related to male reproductive function, interleukin 6 (IL-6) has emerged as a key player. Despite the growing recognition of genetic factors in male infertility, the specific association between the IL-6-174 G/C genetic polymorphism and male infertility remains an area that needs further investigation.

Objective

This investigation explores the correlation between the IL-6-174 G/C transversion and male infertility.

Materials and Methods

In a case-control study, a total of 314 men who referred to the Kashan Infertility Center, Shahid Beheshti hospital, Kashan, Iran, were enrolled for IL-6-174 G/C polymorphism analysis. The study comprised 163 infertile participants as the case group and 151 fertile men as the control group. Following the screening, 2 ml of whole blood was collected from each participant. Cases were categorized into 3 subgroups based on World Health Organization criteria: (i) nonobstructive azoospermia (n = 42), (ii) oligozoospermia (n = 61), and (iii) asthenozoospermia (n = 60). After DNA extraction, genotypes of the samples at the -174 G/C (rs1800795) locus were determined using the polymerase chain reaction-restriction fragment length polymorphism method.

Results

Our genetic investigation demonstrated a significant association between the GC genotype and male infertility. Furthermore, a correlation was observed between the heterozygous GC genotype and reduced risk of oligozoospermia and asthenospermia. Additionally, the C allele was correlated with a decreased risk of infertility and specific subgroups such as oligozoospermia and asthenospermia.

Conclusion

Our findings suggest that the IL-6-174 G/C transversion could potentially serve as a protective genetic factor against male infertility.

Impact of IL-6 and IL-1β Gene Variants on Non-small-cell Lung Cancer Risk in Egyptian Patients

Lung cancer is a serious health and life issue, with the fastest-growing incidence and fatality rates worldwide. It is now clear that inflammation is a key factor involved in all aspects of carcinogenesis, notably lung cancer development. Genetic changes, including polymorphisms in inflammatory genes, are supposed to be a significant cause of increased lung cancer risk. The main idea of this research was to disclose the linkage between both IL-6 rs1800795 and IL-1β rs16944 variants and susceptibility to non-small-cell lung cancer (NSCLC) in Egyptians. This case-control design was composed of 127 cases and 138 controls, which were genotyped using the ARMS-PCR technique. To examine the NSCLC susceptibility under various genetic models, the odds ratio (OR) and 95% confidence intervals (CIs) were determined by logistic regression. Rs1800795 of the IL-6 gene was linked to higher odds of NSCLC under the allele model (adjusted, OR 2.28; 95% CI 1.2-4.33; p = 0.011). In the genetic models, IL-6 rs1800795 elevated the odds of NSCLC, while IL-1β rs16944 decreased the odds of NSCLC. Stratification analysis showed that IL-6 rs1800795 greatly increased the NSCLC risk in females and adenocarcinoma subtypes, whereas IL-1β rs16944 largely decreased the NSCLC risk for males, patients aged < 55, and nonsmokers. Regarding clinical data, the IL-6 variant was remarkably correlated with tumor size. This work primarily established that IL-6 and IL-1β variants have a great impact on NSCLC development in the Egyptian population; thus, it may be a supportive guide for earlier NSCLC prevention.

The Interleukin 6 Protein Level as well as a Genetic Variants, (rs1800795, rs1800797) Are Associated with Adverse Cardiovascular Outcomes within 10-Years Follow-Up

BACKGROUND

Worldwide, cardiovascular disease (CVD) is the leading cause of premature death. The proinflammatory cytokine interleukin 6 (IL-6) is a essential marker of innate immunity that is considered to play an important proatherogenic role for cardiovascular disease. The aim of this study (substudy of ClinTrials.gov identifier: NCT01045070) was to evaluate IL-6 protein level and genetic variants (rs1800795, rs1800797) with respect to CV outcome (combined endpoint: myocardial infarction, stroke/transient ischemic attack, cardiac death, death according to stroke) among patients CVD within 10-years follow-up.

MATERIAL AND METHODS

Overall 1002 in-patients with CVD were included. IL-6 protein level was determined by electrochemiluminescence immunoassay (fasting, between 7 and 8 a.m.). Genetic analyses were carried out by single specific primer-polymerase chain reaction.

RESULTS

In survival analyses, IL-6 protein levels of ≥6.4 pg/mL (log-rank test: p = 0.034; cox regression: p = 0.032, hazard ratio = 1.29) and CC genotype of rs1800795 (log-rank test: p < 0.001, cox regression: p < 0.001, hazard ratio = 1.72) and AA genotype of rs180797 (log-rank test: p = 0.002, cox regression: p < 0.001, hazard ratio = 1.62) were associated with a poorer CV prognosis considering combined CV endpoint.

CONCLUSION

This study was the first to investigate both elevated IL-6 levels and genetic variants for their prognostic value for adverse CV outcomes in CVD patients within the 10-year follow-up period.

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

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

An interleukin 6-based genetic risk score strengthened with interleukin 10 polymorphisms associated with long-term kidney allograft outcomes

Of all kidney transplants, half are still lost in the first decade after transplantation. Here, using genetics, we probed whether interleukin 6 (IL-6) could be a target in kidney transplantation to improve graft survival. Additionally, we investigated if a genetic risk score (GRS) based on IL6 and IL10 variants could improve prognostication of graft loss. In a prospective cohort study, DNA of 1271 donor-recipient kidney transplant pairs was analyzed for the presence of IL6, IL6R, IL10, IL10RA, and IL10RB variants. These polymorphisms and their GRS were then associated with 15-year death-censored allograft survival. The C|C-genotype of the IL6 polymorphism in donor kidneys and the combined C|C-genotype in donor-recipient pairs were both associated with a reduced risk of graft loss (p = .043 and p = .042, respectively). Additionally, the GRS based on IL6, IL6R, IL10, IL10RA, and IL10RB variants was independently associated with the risk of graft loss (HR 1.53, 95%-CI [1.32-1.84]; p < .001). Notably, the GRS improved risk stratification and prediction of graft loss beyond the level of contemporary clinical markers. Our findings reveal the merits of a polygenic IL-6-based risk score strengthened with IL-10- polymorphisms for the prognostication and risk stratification of late graft failure in kidney transplantation.

Donor genetic variants in interleukin-6 and interleukin-6 receptor associate with biopsy-proven rejection following kidney transplantation

Rejection after kidney transplantation remains an important cause of allograft failure that markedly impacts morbidity. Cytokines are a major player in rejection, and we, therefore, explored the impact of interleukin-6 (IL6) and IL-6 receptor (IL6R) gene polymorphisms on the occurrence of rejection after renal transplantation. We performed an observational cohort study analyzing both donor and recipient DNA in 1271 renal transplant‐pairs from the University Medical Center Groningen in The Netherlands and associated single nucleotide polymorphisms (SNPs) with biopsy-proven rejection after kidney transplantation. The C-allele of the IL6R SNP (Asp358Ala; rs2228145 A > C, formerly rs8192284) in donor kidneys conferred a reduced risk of rejection following renal transplantation (HR 0.78 per C-allele; 95%-CI 0.67–0.90; P = 0.001). On the other hand, the C-allele of the IL6 SNP (at position-174 in the promoter; rs1800795 G > C) in donor kidneys was associated with an increased risk of rejection for male organ donors (HR per C-allele 1.31; 95%-CI 1.08–1.58; P = 0.0006), but not female organ donors (P = 0.33). In contrast, neither the IL6 nor IL6R SNP in the recipient showed an association with renal transplant rejection. In conclusion, donor IL6 and IL6R genotypes but not recipient genotypes represent an independent prognostic marker for biopsy-proven renal allograft rejection.

Interleukin 6 (rs1800795) and pentraxin 3 (rs2305619) polymorphisms-association with inflammation and all-cause mortality in end-stage-renal disease patients on dialysis

Chronic inflammation plays an important role in the progression and outcome of chronic kidney disease (CKD). The circulating levels of the inflammatory biomarkers interleukin 6 (IL6) and pentraxin 3 (PTX3) are enhanced in CKD patients, and are associated with the progression of the disease and with higher risk for cardiovascular events, the major cause of death in CKD patients. Our aim was to study how specific polymorphisms of IL6 and PTX3 encoding genes affect the inflammatory response and outcome of end-stage renal disease (ESRD) patients on dialysis. Methodology included the analysis of two single nucleotide polymorphisms (SNP), namely the IL6 (rs1800795) polymorphism in the promoter region (-174G > C), and the PTX3 (rs2305619) polymorphism in the intron 1 (+ 281A > G), which were analyzed in ESRD patients on dialysis and in a group of heathy individuals. The allelic frequencies, genotype distribution and their association with circulating levels of the inflammatory markers C-reactive protein (CRP), IL6, growth differentiation factor 15 (GDF15) and PTX3, were determined in ESRD patients. Events of death were recorded along one year, to assess the association of the studied SNPs with all-cause mortality and the inflammatory biomarkers, in ESRD patients. Results showed that the allelic frequencies and genotype distribution for IL6 and PTX3 SNPs in the control group and ESRD patients were similar and in agreement with other European reports. For the IL6 polymorphism, we found a trend towards higher levels of high-sensitivity (hs) CRP, IL6 and PTX3 in the homozygous genotypes; the CC genotype also showed the highest levels of GDF15. The mortality rate after the 1-year follow-up was 10.4%. The CC genotype (IL6 SNP) was associated to a higher risk of mortality and deceased patients carrying this genotype also showed the highest levels of hsCRP. Regarding the studied PTX3 SNP, the AA genotype was linked to an enhanced inflammatory response, showing the highest values of hsCRP and IL6. Nevertheless, this genotype had no significant impact on the mortality rate. In conclusion, both studied SNPs seem to modulate the inflammatory response in ESRD and may, therefore, be determinant on disease progression and patients' outcome. Our data also highlights the importance of research on genetic variants that, although less frequent, may have significant biological value.

Anti-Inflammatory Therapy for Atherosclerosis: Focusing on Cytokines

Atherosclerosis is a well-known global health problem. Despite the high prevalence of the disease, numerous aspects of pathogenesis remain unclear. Subsequently, there are still no cure or adequate preventive measures available. Atherogenesis is now considered a complex interplay between lipid metabolism alterations, oxidative stress, and inflammation. Inflammation in atherogenesis involves cellular elements of both innate (such as macrophages and monocytes) and adaptive immunity (such as B-cells and T-cells), as well as various cytokines cascades. Because inflammation is, in general, a well-investigated therapeutic target, and strategies for controlling inflammation have been successfully used to combat a number of other diseases, inflammation seems to be the preferred target for the treatment of atherosclerosis as well. In this review, we summarized data on targeting the most studied inflammatory molecular targets, CRP, IL-1β, IL-6, IFN-γ, and TNF-α. Studies in animal models have shown the efficacy of anti-inflammatory therapy, while clinical studies revealed the incompetence of existing data, which blocks the development of an effective atheroprotective drug. However, all data on cytokine targeting give evidence that anti-inflammatory therapy can be a part of a complex treatment.

Polymorphisms of Pro-Inflammatory IL-6 and IL-1β Cytokines in Ascending Aortic Aneurysms as Genetic Modifiers and Predictive and Prognostic Biomarkers

Background: Previous studies have demonstrated that polymorphisms involved in immune genes can affect the risk, pathogenesis, and outcome of thoracic ascending aortic aneurysms (TAAA). Here, we explored the potential associations of five functional promoter polymorphisms in interleukin-6 (IL-6), IL-1B, IL-1A, IL-18, and Tumor necrosis factor (TNF)A genes with TAAA. Methods: 144 TAAA patients and 150 age/gender matched controls were typed using KASPar assays. Effects on telomere length and levels of TAAA related histopathological and serological markers were analyzed. Results: Significant associations with TAAA risk were obtained for IL-6 rs1800795G>C and IL-1B rs16944C>T SNPs. In addition, the combined rs1800795C/rs16944T genotype showed a synergic effect on TAAA pathogenesis and outcome. The combined rs1800795C/rs16944T genotype was significantly associated with: (a) higher serum levels of both cytokines and MMP-9 and -2; (b) a significant CD3+CD4+CD8+ CD68+CD20+ cell infiltration in aorta aneurysm tissues; (c) a significant shorter telomere length and alterations in telomerase activity. Finally, it significantly correlated with TAAA aorta tissue alterations, including elastic fragmentation, medial cell apoptosis, cystic medial changes, and MMP-9 levels. Conclusions: the combined rs1800795C/rs16944T genotype appears to modulate TAAA risk, pathogenesis, and outcome, and consequently can represent a potential predictive and prognostic TAAA biomarker for individual management, implementation of innovative treatments, and selection of the more proper surgical timing and approaches.

Common genetic variants and pathways in diabetes and associated complications and vulnerability of populations with different ethnic origins

Diabetes mellitus is a complex and heterogeneous metabolic disorder which is often pre- or post-existent with complications such as cardiovascular disease, hypertension, inflammation, chronic kidney disease, diabetic retino- and nephropathies. However, the frequencies of these co-morbidities vary among individuals and across populations. It is, therefore, not unlikely that certain genetic variants might commonly contribute to these conditions. Here, we identified four single nucleotide polymorphisms (rs5186, rs1800795, rs1799983 and rs1800629 in AGTR1, IL6, NOS3 and TNFA genes, respectively) to be commonly associated with each of these conditions. We explored their possible interplay in diabetes and associated complications. The variant allele and haplotype frequencies at these polymorphic loci vary among different super-populations (African, European, admixed Americans, South and East Asians). The variant alleles are particularly highly prevalent in different European and admixed American populations. Differential distribution of these variants in different ethnic groups suggests that certain drugs might be more effective in selective populations rather than all. Therefore, population specific genetic architectures should be considered before considering a drug for these conditions.

The effect of polymorphisms (174G> C and 572C> G) on the Interleukin-6 gene in coronary artery disease: a systematic review and meta-analysis

BACKGROUND

Coronary Artery Disease (CAD) is caused by the blockage of the coronary arteries. it is argued that there has an association between the Interleukin-6 gene and the occurrence of atherosclerosis, coronary artery disease, Due to the short half-life and high variability of Interleukin-6 (IL-6), limited studies have been performed on the association of serum levels of interleukin-6 with coronary artery disease. The aim of this study is to investigate the relationship between IL-6 gene polymorphisms and coronary artery disease.

METHODS

This study was conducted as a meta-analysis of selected articles with no lower time limit and upto March 2020. Articles related to the subject were obtained by searching several data sources,such as the SID, IranDoc, Scopus, Embase, Web of Science (ISI), PubMed, Science Direct, and Google Scholar databases. The heterogeneity of the studies was assessed using the I2 index in the Comprehensive Meta-Analysis software.

RESULTS

The GG genotype of the IL-6174 G> C polymorphism with a 0.8 odds ratio tended to reduce the risk of CAD by 20%. The odds ratio of CAD in CG and GG genotypes were found to be 1.16 and 1.48 times respectively, indicating the increasing effect of these two genotypes. In the IL-6-572 C>G polymorphism, CG and GG genotypes increased the risk of CAD by 1.21 and 1.27 times respectively, and the CC genotype tended to reduce the risk of CAD by 15%, considering the odds ratio of 0.85.

CONCLUSION

This study showed a relationship between IL-6174G> C and Interleukin-6 (IL-6) 572 C>G genes and coronary artery disease. Moreover, the protective effects of GG genotype in IL-6 gene 174 G> C and CC genotype in IL-6 gene 572 C>G gene were reported. The study also confirmed that the CG and CC genotypes of the G>C IL-6174 gene have an increasing effect on coronary artery disease. Moreover, CG and GG genotypes in the IL-6 gene 572 C>G increased the risk of developing CAD. It should be noted that the increased risk of developing CAD was limited to meta-analytic studies in reported literatures.

MicroRNA-668-3p Protects Against Oxygen-Glucose Deprivation in a Rat H9c2 Cardiomyocyte Model of Ischemia-Reperfusion Injury by Targeting the Stromal Cell-Derived Factor-1 (SDF-1)/CXCR4 Signaling Pathway

Background

Ischemia-reperfusion injury (IRI) results from the restoration of blood supply to ischemic organs, including the heart. Expression of microRNA-668-3p (miR-668-3p) is known to protect the kidney from IRI. This study aimed to investigate the role of miR-668-3p in oxygen-glucose deprivation (OGD) in a rat H9c2 cardiomyocyte model of IRI.

Material/Methods

Rat H9c2 cardiomyocytes were cultured in glucose-free Dulbecco’s modified Eagle’s medium (DMEM) under anaerobic conditions, followed by oxygenation, to create the OGD model of IRI. The luciferase reporter assay evaluated the interaction between stromal cell-derived factor-1 (SDF-1), or CXC motif chemokine 12 (CXCL12), and miR-668-3p. Protein and mRNA levels of SDF-1, CXCR4, Bcl2, Bax, cleaved caspase-3, endothelial nitric oxide synthase (eNOS), and phosphorylated endothelial nitric oxide synthase (p-eNOS) were analyzed by Western blot and quantitative reverse transcription-polymerase chain reaction (RT-qPCR), and apoptosis were assessed by flow cytometry. Enzyme-linked immunosorbent assay (ELISA) measured reactive oxygen species (ROS), including malondialdehyde (MDA), nitric oxide (NO), p-eNOS, and the inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and monocyte chemoattractant protein-1 (MCP-1) in H9c2 cell supernatants.

Results

In the OGD rat H9c2 cardiomyocyte model of IRI, miR-668-3p levels were reduced. Overexpression of miR-668-3p inhibited SDF-1, CXCR4, the expression of inflammatory cytokines, markers of oxidative stress, and p-eNOS. The overexpression of SDF-1 reversed these findings. Overexpression of SDF-1 promoted cell apoptosis, which was reduced by miR-668-3p.

Conclusions

In the OGD rat H9c2 cardiomyocyte model of IRI, miR-668-3p suppressed mediators of inflammation and oxidative stress and enhanced cell viability through the SDF-1/CXCR4 signaling pathway.