The G to C polymorphism at -174 of the interleukin-6 gene is rare in a Southern Chinese population

Association between Interleukin-6 Gene Polymorphism (rs1800795 and rs1800796) and Type 2 Diabetes Mellitus in a Ghanaian Population: A Case-Control Study in the Ho Municipality

Background

There is no conclusive evidence on the association between interleukin- (IL-) 6 gene polymorphism and type 2 diabetes mellitus (type 2 DM). Thus, this study is aimed at evaluating the role of rs1800795 and rs1800796 polymorphisms in the pathogenesis of type 2 DM among Ghanaians in the Ho Municipality.

Materials and Methods

We recruited into this hospital-based case-control study 174 patients with type 2 DM (75 DM alone and 99 with DM+HTN) and 149 healthy individuals between 2018 and 2020. Demographic, lifestyle, clinical, anthropometric, and haemodynamic variables were obtained. Fasting blood samples were collected for haematological, biochemical, and molecular analyses. Genomic DNA was extracted, amplified using Tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) technique, and genotyped for IL-6 gene polymorphism. Logistic regression analyses were performed to assess the association between IL-6 gene polymorphism and type 2 DM.

Results

The minor allele frequency (MAF) of the rs1800795 and rs1800796 polymorphisms was higher in DM alone (57.5%, 62.0%) and DM with HTN groups (58.3%, 65.3%) than controls (33.1%, 20.0%). Carriers of the rs1800795GC genotype (aOR = 2.35, 95% CI: 1.13-4.90, p = 0.022) and mutant C allele (aOR = 2.41, 95% CI: 1.16-5.00, p = 0.019) as well as those who carried the rs1800796GC (aOR = 8.67, 95% CI: 4.00-18.90, p < 0.001) and mutant C allele (aOR = 8.84, 95% CI: 4.06-19.26, p = 0.001) had increased odds of type 2 DM. For both polymorphisms, carriers of the GC genotype had comparable levels of insulin, HOMA-IR, and fasting blood glucose (FBG) with those who carried the GG genotype. IL-6 levels were higher among carriers of the rs1800796GC variant compared to carriers of the rs1800796GG variant (p = 0.023). The rs1800796 polymorphism, dietary sugar intake, and exercise status, respectively, explained approximately 3% (p = 0.046), 3.2% (p = 0.038, coefficient = 1.456), and 6.2% (p = 0.004, coefficient = -2.754) of the variability in IL-6 levels, suggesting weak effect sizes.

Conclusion

The GC genotype and mutant C allele are risk genetic variants associated with type 2 DM in the Ghanaian population. The rs1800796 GC variant, dietary sugar intake, and exercise status appear to contribute significantly to the variations in circulating IL-6 levels but with weak effect sizes.

Genetic susceptibility in pneumoconiosis in China: a systematic review

OBJECTIVE

Pneumoconiosis, encompassing coal workers' pneumoconiosis (CWP), silicosis and asbestosis, is one of the most common occupational diseases in China. Previous studies revealed significant associations between genetic variations and pneumoconiosis risk among individuals in different countries. With the known variability of genetic makeup between ethnicities, susceptibility to pneumoconiosis due to genetic differences is likely to be ethnicity-specific. The present review aimed at providing a comprehensive overview on the association between genetic polymorphisms and susceptibility of pneumoconiosis, specifically among people in China.

METHODS

The literature search was performed in seven English and Chinese databases using keywords related to the review aim. An appraisal of the methodological quality of the included studies was conducted using the assessment tool derived from the Strengthening the Reporting of Genetic Association Studies (STREGA) statement.

RESULTS

Forty-five studies were included in this review. Genotypes of specific genes which are associated with the risk of CWP, silicosis and asbestosis were reported. Our findings showed that genes encoding inflammatory cytokines have been examined extensively, and they demonstrated an association between these genes and pneumoconiosis risk. Gene-environment interactions in pneumoconiosis susceptibility were also reported by a number of studies.

CONCLUSIONS

This review summarised the evidence demonstrating the association between genetic polymorphisms and pneumoconiosis susceptibility among people in China, and that various genotypes could modify their risk to develop pneumoconiosis. The findings prompt that identification of individuals at high pneumoconiosis risk through genetic screening and strategies limiting their exposure to dust could be a potential strategy for the control of this occupational disease in China.

No Interaction Effect between Interleukin-6 Polymorphisms and Acid Ash Diet with Bone Resorption Marker in Postmenopausal Women

Background: Evidence is growing that a high-acid diet might accelerate the rate of bone loss, and gene polymorphisms such as Interleukin 6 (IL6) -174G/C and -572G/C are related to bone deterioration. However, no study of the interaction between diet and IL6 polymorphisms has been conducted among Asians. Thus, the objective of this study was to determine whether IL6 gene polymorphisms modified the association between dietary acidity and the rate of bone resorption. Methods: This cross-sectional study recruited 203 postmenopausal women (age ranged from 51 to 85 years old) in community settings. The dietary intakes of the participants were assessed using a validated interviewer-administered semi-quantitative food frequency questionnaire (FFQ), while dietary acid load (DAL) was estimated using net endogenous acid production (NEAP). Agena^® MassARRAY genotyping analysis and serum collagen type 1 cross-linked C-telopeptide (CTX1) were used to identify the IL6 genotype and as a bone resorption marker, respectively. The interactions between diet and single-nucleotide polymorphisms (SNPs) were assessed using linear regressions. Results: A total of 203 healthy postmenopausal women aged between 51 and 85 years participated in this study. The mean BMI of the participants was 24.3 kg/m². In IL6 -174 G/C, all the participants carried the GG genotype, while the C allele was absent. Approximately 40% of the participants had a high dietary acid load. Dietary acid load (B = 0.15, p = 0.031) and the IL6 -572 CC genotype group (B = 0.14, p = 0.044) were positively associated with a higher bone resorption. However, there was no moderating effect of the IL6 genetic polymorphism on the relationship between and acid ash diet and bone resorption markers among the postmenopausal women (p = 0.79). Conclusion: High consumption of an acid ash diet and the IL6 -572 C allele seem to attribute to high bone resorption among postmenopausal women. However, our finding does not support the interaction effect of dietary acidity and IL6 (-174G/C and -572G/C) polymorphisms on the rate of bone resorption. Taken together, these results have given scientific research other candidate genes to focus on which may interact with DAL on bone resorption, to enhance planning for preventing or delaying the onset of osteoporosis among postmenopausal women.

Interleukin-6 Receptor Asp358 A>C Polymorphism Is Associated With Postoperative Atrial Fibrillation

BACKGROUND

This study examined the associations of single-nucleotide polymorphisms in the interleukin-6 receptor gene (Asp358 A>C) and the interleukin-6 promoter (-174G>C and -597G>A) with interleukin-6 levels and postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG).

METHODS

The study enrolled 371 Chinese Han patients who were undergoing CABG. Serum interleukin-6 levels were measured preoperatively and at 6, 12, and 18 hours postoperatively. Genotypes for the 3 polymorphisms were determined.

RESULTS

Overall, POAF developed in 30.2% of patients. The CC genotype and C allele frequencies for the interleukin-6 receptor Asp358 A>C polymorphism were significantly higher in patients with POAF than in patients without POAF (P = .003), and the interleukin-6 levels were significantly higher in patients with the CC genotype compared with A allele carriers at 6, 12, and 18 hours in the overall cohort and at 12 and 18 hours in the POAF subgroup, but there were no significant differences in the non-POAF subgroup. However, the allele and genotype frequencies of the interleukin-6 -174G>C and -597G>A polymorphisms were similar among groups, and there were no differences in interleukin-6 levels at any time point between the C/A allele carriers and the patients with GG genotypes. Univariate analysis showed that the CC genotype for interleukin-6 receptor Asp358 A>C, age, and history of cerebrovascular disease were associated with POAF. Multivariable regression showed that the CC genotype was independently related to the development of POAF (odds ratio, 2.01; 95% confidence interval: 1.15 to 3.52; P = .014).

CONCLUSIONS

The interleukin-6 receptor Asp358 A>C polymorphism may contribute to genetic susceptibility to POAF after CABG.

Meta-analysis of association between il-6-174 g/c polymorphism and female infertility related disorders

Female infertility continues to increase in prevalence annually and factors causing it need to be researched. As IL-6-174 G/C polymorphism is known to alter the plasma levels of IL-6, abnormal levels of IL-6 found in infertile females could be due to genetic reasons. With the understanding of the importance of IL-6 in reproductive physiology, several individual studies done so far to find the association of this polymorphism with female infertility related disorders were systematically combined for meta-analysis. Articles were searched using electronic data base sources and were included based on specific criteria. Finally, eight articles which includes polycystic ovarian syndrome (PCOS; n = 4), endometriosis (n = 3) and tubal damage (n = 1) were selected for the analysis. Results showed statistically significant heterogeneity across studies under the allele model (p < 0.0001, I² = 78 %) and dominant model (p < 0.00001, I² = 82%) but not under recessive model (p = 0.31, I² = 16%). This difference could be possibly due to variation in ethnicity, lifestyle, age or BMI related factors. The pooled odds ratio under the three genetic models were 0.87(CI = 0.75-1.02), 0.77 (CI = 0.63-0.94) and 1.05 (CI = 0.76-1.46) respectively. Sub group analysis showed statistical significant (P < 0.01) for PCOS under allele and dominant model, but not for endometriosis and tubal damage. By this meta-analysis, we can say that IL-6-174 G/C polymorphism can be considered as a potential genetic marker for PCOS but not for endometriosis and tubal damage disorders. However, more studies with adequate sample sizes are required to be done in endometriosis, tubal disease and other female infertility disorders to arrive at a definite conclusion.

Interleukin-1β and interleukin-6 gene polymorphisms in Egyptian sickle cell disease patients

Background

Sickle cell disease (SCD) is a disorder characterized by a heterogeneous clinical outcome. Interleukin-1β (IL-1β) and interleukin-6 (IL-6) are important mediators of inflammatory response. Genetic modifiers that alter cytokine levels may contribute to the clinical variability of SCD. The present study investigated the associations of IL-1β + 3954 C>T and IL-6 (− 174G>C and − 597 G>A) gene polymorphisms with clinical and laboratory data in SCD patients. The study was conducted on 100 SCD patients (59 sickle cell anemia patients “SS” and 41 sickle beta thalassemia patients “Sβ”). Fifty age- and sex-matched healthy volunteers were included as a control group. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for the detection of IL-1β and IL-6 gene polymorphisms.

Results

The homomutant genotypes of IL-1β (+ 3954 C>T), IL-6 (− 174G>C), and IL-6 (− 597 G>A) were infrequently presented among SCD patients and control group. No significant differences were detected between SS, Sβ patients, and control group as regards the genotypic frequencies and allele distributions of the studied polymorphisms. As regards the clinical complications, the mutant genotypes of IL-1β (+ 3954 C>T) had a significantly higher frequency among Sβ patients with splenomegaly. Hemoglobin is significantly lower in SS patients with mutant allele (AA and GA) for IL-6 (− 597 G>A) (P = 0.005), while Sβ patients with mutant genotype for IL-6 (− 597 G>A) had significantly higher total leucocytic count (P = 0.031).

Conclusion

IL-1β (+ 3954 C>T), IL-6 (− 174G>C), and IL-6 (− 597G>A) polymorphisms are not associated with disease phenotype. However, IL6 polymorphism (− 597 G>A) might predispose to underlying inflammatory process.

The association between interleukin-6 gene -174G/C single nucleotide polymorphism and sepsis: an updated meta-analysis with trial sequential analysis

Background

This article intends to explore the association between interleukin-6 gene (IL-6) -174 G/C single nucleotide polymorphism (SNP) and the risk and mortality of sepsis by conducting this updated meta-analysis with trial sequential analysis.

Methods

References were made to PubMed, Web of Science, China National Knowledge Infrastructure for studies available by September 2018. Each publication was screened for its eligibility and data accessible. Statistical analysis was conducted on Stata 14.1 and TSA software 0.9.5.10 Beta

Results

Twenty studies (including 3282 cases and 4926 controls) and eight studies (including 610 cases and 1856 controls) were respectively enrolled in the analysis on the association between IL-6-174 G/C polymorphism and the risk and mortality of sepsis. The results did not present any association between IL-6-174 G/C polymorphism and the risk and mortality of sepsis. An exception was that IL-6-174 G/C polymorphism was correlated with worse outcome in non-adults in recessive model, co-dominant model (CC vs. GG) and allelic model, while trial sequential analysis revealed it could be a false positive result nevertheless.

Conclusions

IL-6-174 G/C polymorphism is not associated with the risk and mortality of sepsis. Trial sequential analysis showed that a large sample size was needed to get a more reliable result of the association between IL-6-174 G/C polymorphism and sepsis in non-adults.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0766-2) contains supplementary material, which is available to authorized users.

Polymorphisms in promoter regions of MMP-3 and IL-6 genes are not associated to adolescent idiopathic scoliosis (AIS) gender bias

STUDY DESIGN

A retrospective study in Chinese Han people.

PURPOSE

To explore whether promoter polymorphisms of matrix metalloproteinases-3 (MMP-3) (rs3025058) and interleukin-6(IL-6) (rs1800795) genes are associated to AIS gender bias.

METHODS

A total of 200 patients (100 boys and 100 girls) with AIS and 200 healthy age-matched adolescents were recruited from July 2008 to August 2013 in our scoliosis center. All AIS patients had Cobb angles larger than 20°, average 43 ± 3.6° (range 24-72°). A case-control study using genotypic technique was conducted to explore whether promoter polymorphisms of MMP-3 and IL-6 were associated to AIS gender bias. In addition, to confirm the association between gene variants of MMP-3 and IL-6 and AIS. Statistical analysis of genotype frequencies between AIS patients and normal controls was performed by X^2 test.

RESULTS

The frequency of 5A/5A genotype of MMP-3 gene in patients with AIS was higher than in controls (19% versus 9.5% p= 0.007), in the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of 5A/5A genotype of MMP-3 (20% in girls versus 18% in boys p= 0.718). No significant difference was found between AIS and controls in the frequency of G/G genotype of IL-6 (97.5% versus 98%). In the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of G/G genotype of the IL-6 gene (98% in girls versus 97% for boys).

CONCLUSIONS

The promoter polymorphism of the MMP-3 gene was confirmed to have an association with AIS and the promoter polymorphism of the IL-6 gene was lack of association with AIS. Besides, both gene variants of MMP-3 and IL-6 were not associated to AIS gender bias.

Interleukin-6 gene polymorphisms correlate with the progression of nephropathy in Chinese patients with type 2 diabetes: A prospective cohort study

AIMS

Interleukin-6 (IL-6), an inflammatory cytokine, is considered a candidate gene possibly involved in susceptibility to nephropathy in diabetes. This study aimed to examine whether IL-6 polymorphisms predict the progression of nephropathy in a prospective Chinese cohort of patients with type 2 diabetes.

METHODS

A total of 568 type 2 diabetic patients with normoalbuminuria at baseline were followed up for a mean of 5.3±1.5years. Urinary albumin-to-creatinine ratio (ACR) ⩾30mg/g in two consecutive urine tests were defined as progression to diabetic nephropathy (n=143). Five polymorphisms of IL-6 gene, rs1800795, rs1800796, rs1524107, rs2069837, and rs2069840, were genotyped. Cox proportional hazard models were used to estimate hazard ratio (HR) and 95% CI of progression to diabetic nephropathy under different genetic models.

RESULTS

Almost all patients (99.6%) carried the rs1800795 GG homozygous genotypes. In the Cox proportional models adjusted for multiple covariates, the HR under recessive model was 2.02 for rs1800796 GG (vs. CC+CG, 95% CI: 1.08-3.75, p=0.027), 2.37 for rs2069837 GG (vs. AA+AG, 95% CI: 1.15-4.87, p=0.019), and 2.08 for rs1524107 CC (vs. TT+TC, 95% CI: 1.12-3.89, p=0.021). These associations remained significant for rs1800796 and rs1524107 after correction for multiple testing (α=0.017). Overall, our results suggest that rs1800796 GG and rs1524107 CC homozygous genotypes may confer a greater risk for development of nephropathy in type 2 diabetes.

CONCLUSIONS

IL-6 gene polymorphisms rs1800796 and rs1524107 may serve as predictors of progression of nephropathy in Chinese patients with type 2 diabetes.

Significant impact of IL-6 -174G/C but inverse relation with -634 C/G polymorphism in patients with non-small cell lung cancer in Kashmiri population

To study the possible role of proinflammatory interleukin 6 -174 G>C (rs 1800795) and -634 C>G (rs 1800796) polymorphism in the pathogenesis of non-small cell lung cancer (NSCLC). A total of 190 NSCLC patients and 200 healthy controls were evaluated for polymorphic analysis of -174 G/C and -634 C/G by PCR-RFLP followed by DNA sequencing. A significant association was observed in the genotypic and allelic distribution of IL-6 -174 G/C in the NSCLC group as compared to control group [OR = 2.7 (1.77-4.11), p < 0.0001]. Smokers with the -174C allele were found to be significantly associated with NSCLC (p = 0.01), while 634C/G SNP showed an inverse relation [OR-0.4, p < 0.0001]. The present investigation revealed a significant association of the IL6 -174 G/C gene promoter polymorphism with NSCLC, and thus, the IL-6 -174G/C genotype can be considered as one of the biological markers in the etiology of NSCLC.

Association of interleukin-6-572C/G gene polymorphism and serum or cerebrospinal fluid interleukin-6 level with enterovirus 71 encephalitis in Chinese Han patients with hand, foot, and mouth disease

Interleukin-6 (IL-6), as one of pro-inflammatory cytokines, plays a key role in Enterovirus 71 (EV71) encephalitis. We investigated the association of IL-6-572C/G polymorphism and serum or cerebrospinal fluid (CSF) IL-6 level with EV71 encephalitis in patients with hand, foot, and mouth disease (HFMD). This study was carried out in 59 Chinese Han patients with EV71 encephalitis, 128 EV71-related HFMD without complications, and 232 controls. The IL-6-572C/G polymorphism was detected by polymerase chain reaction-restricted fragment length polymorphism gene analysis. Serum or CSF IL-6 levels were determined using a commercial enzyme-linked immunosorbent assay. The patients with EV71 encephalitis had a higher frequency of IL-6-572GG/GC genotype compared to the patients with EV71-related HFMD without encephalitis complications (40.7 vs. 15.6 %, odds ratio (OR)=3.70, 95 % confidence interval (CI)=1.83-7.50, p=0.001). Similarly, the frequency of IL-6-572 G allele among the patients with EV71 encephalitis was also higher than that of patients with EV71-related HFMD without encephalitis complications (23.7 vs. 8.6 %, OR=3.31, 95 % CI=1.80-6.08, p<0.001). Serum IL-6 levels in G carries (CG + GG) (195.1 ± 11.8 pg/ml) elevated significantly compared to CC homozygotes (167.7 ± 6.7 pg/ml) in EV71-infected patients (p<0.001), but no significant differences were observed in CSF IL-6 levels among different genotypes in patients with EV71 encephalitis. Furthermore, G carriers (GG + GC) (10.6 ±.29 mg/l) had significantly higher blood CRP levels compared to CC homozygotes (9.31 ± 1.93 mg/l) in patients with EV71 encephalitis (p=0.005). These findings suggested that IL-6-572 G allele was significantly associated with the susceptibility to EV71 encephalitis in Chinese Han patients, and IL-6-572 G allele might elevate the risk to EV71 encephalitis.

Association between IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms and susceptibility to recurrent pregnancy loss: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether interleukin-6 (IL-6) -174 G/C, IL-6 -634 G/C, and interferon-γ (IFN-γ) +874 A/T polymorphisms are associated with susceptibility to recurrent pregnancy loss (RPL).

METHODS

We conducted a literature search using PubMed and EMBASE databases and performed a meta-analysis using fixed- or random-effects models.

RESULTS

A total of 15 articles met the study inclusion criteria. When all study subjects were considered together, meta-analysis showed no association between RPL and the IL-6 -174 GG + GC genotype (odds ratio [OR] = 0.794, 95 % confidence interval [CI] = 0.542-1.163, p = 0.236). However, stratification of the data by ethnicity indicated an association between this genotype and RPL in non-Caucasians (OR = 0.528, 95 % CI = 0.302-0.925, p = 0.028), but not in Caucasian populations. Moreover, meta-analysis revealed an association between RPL and the IL-6 -634 GG + GC genotype in all study subjects (OR = 0.556, 95 % CI = 0.383-0.806, p = 0.002), while stratification by ethnicity revealed a negative association between this genotype and RPL in Asian (OR = 0.545, 95 % CI = 0.371-0.800, p = 0.002) but not Middle Eastern populations. Furthermore, a relationship between the IFN-γ +874 A allele and RPL was identified in non-Caucasians (OR = 1.403, 95 % CI = 1.133-1.734, p = 0.002), but not in Caucasians.

CONCLUSIONS

This meta-analysis demonstrates that IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms are associated with susceptibility to RPL, particularly in non-Caucasians.

IL-6 572 C/G, 190 C/T, and 174 G/C gene polymorphisms in children's malnutrition

OBJECTIVES

The aim of the present study was to establish the correlations between the polymorphisms of the genes interleukin-6 (IL-6) 572, 190, and 174 in children's malnutrition.

METHODS

We assessed 283 hospitalized children and divided them into 2 groups: group I (control) included 110 patients with normal nutritional status, median (range) age 10.90 (1-18) years; and group II consisted of 173 malnourished patients, median (range) age 10.70 (1-18) years.

RESULTS

The 2 groups underwent IL-6 572 cytosine allele (C)/guanine allele (G), 190 C/thymine allele (T), and 174 G/C polymorphism testing, measurement of anthropometric indicators (mid-upper arm circumference and tricipital skinfold thickness [TST]), and paraclinical evaluation (protein, albumin). We observed that the GG and CG genotypes were more frequent in malnourished children for the IL-6 174 gene (P = 0.0001), whereas the CT heterozygous genotype was more frequent in the malnourished group for the IL-6 190 gene (P = 0.003). Body mass index (BMI), middle upper arm circumference (MUAC), TST, and low serum albumin levels correlated with the GG and CG genotypes of the IL-6 572 and IL-6 174 genes, and with the CT genotype of the IL-6 190 gene, in children with malnutrition, whereas the IL-6 190 TT genotype was a protective factor for malnutrition (P = 0.0001).

CONCLUSIONS

Malnutrition is more frequently associated in children with IL-6 174 G allele carriers (GG and CG genotypes), whereas IL-6 190 TT genotype has a protective function. In malnourished children, the IL-6 572/190/174 GG/CT/CG, GG/CT/GG, GG/CC/GG, and GG/CC/CG combined genotypes are more frequent.

Role of cytokine gene (interferon-γ, transforming growth factor-β1, tumor necrosis factor-α, interleukin-6, and interleukin-10) polymorphisms in the risk of oral precancerous lesions in Taiwanese

Oral squamous cell carcinoma can be preceded by some benign oral lesions with malignant potential, including leukoplakia, erythroplakia, oral lichen planus, and oral submucous fibrosis. There are different degrees of inflammatory cells infiltration in histopathology. Inflammatory cytokines may play a pathogenic role in the development of oral precancerous lesions (OPCLs). Genetic polymorphisms of cytokine-encoding genes are known to predispose to malignant disease. We hypothesized that the risk of OPCLs might be associated with cytokine gene polymorphisms of interferon (IFN)-γ, transforming growth factor (TGF)-β1, tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10. In the present study, 42 OPCL patients and 128 controls were analyzed for eight polymorphisms in five different cytokine genes [IFN-γ (+874 T/A), TGF-β1 (codons 10 T/C and 25 G/C), TNF-α (-308 G/A), IL-6 (-174 G/C), and IL-10 (-1082 A/G, -819 T/C, and -592 A/C)]. Cytokine genotyping was determined by the polymerase chain reaction sequence-specific primer technique using commercial primers. Allele and genotype data were analyzed for significance of differences between cases and controls using the Chi-square (χ(2)) test. Two-sided p < 0.05 were considered to be statistically significant. A series of multivariate logistic regression models, adjusted for age, sex, betel quid chewing, alcohol consumption, and smoking, was constructed in order to access the contribution of homozygous or heterozygous variant genotypes of polymorphisms. The TNF-α (-308) polymorphism was significantly associated with OPCLs. There were significant differences in the distribution of AA, GA, and GG genotypes between OPCL patients and controls (p = 0.0004). Patients with the AA or GA genotype had a 3.63-fold increased risk of OPCLs. The TGF-β1 (codon 10 and 25) polymorphism was also significantly associated with OPCLs (p < 0.001). The IL-6 polymorphism was significantly associated with OPCLs. There are significant differences in the distribution of CC, GC, and GG genotypes between OPCL patients and controls (p < 0.001). Patients with the CC or GC genotype had a 35- or 20.59-fold increased risk of OPCLs. There were no significant differences in the distribution of IL-10 and IFN-γ genotypes between different groups of control individuals and OPCL patients. The IL-6, TGF-β1, and TNF-α gene polymorphisms may have a significant association with the development of OPCLs.

Interleukin 6 -174G>C polymorphism and cancer risk: meta-analysis reveals a site dependent differential influence in Ancestral North Indians

In our earlier studies, single nucleotide polymorphisms (SNPs) associated with anti-inflammatory cytokines were found to influence risk for breast cancer in western Indian women. Analysis of Interleukin 6 (IL-6) -174G>C polymorphism in this cohort (patients = 182; controls = 236) suggested a protective role for IL-6 -174C allele associated with the lower expression of the cytokine (OR = 0.54; 95% CI 0.32-0.89, dominant model). Together these observations suggested that in comparison to Caucasians, inflammation associated-cytokine gene polymorphisms may have higher influence on risk for cancer in this population. To examine this possibility we analyzed data assessing influence of Interleukin 6 (IL-6) -174G>C polymorphism on risk for various cancers. Overall, there was a marginally higher risk for rare allele homozygotes compared to wild type homozygotes (OR = 1.07; 95% CI 1.00-1.15). Increased risks for genitourinary cancers and for skin cancer were also indicated. The ethnicity based analysis indicated a protective effect of the minor allele in Ancestral North Indians (OR = 0.73; 95% CI 0.55-0.97). Site by ethnicity analysis once again revealed a significant protection against breast cancer (OR = 0.51; 95% CI = 0.37-0.70; dominant model) but an opposite influence on the risk of genitourinary malignancies (OR = 2.51; 95% CI 1.59-3.96; recessive model) in this population alone. The observations imply that contribution of IL-6 to inflammation or effector immunity may depend on the site of malignancy. Assessment of available data in relation to prognosis in breast cancer patients also revealed trends that are compatible with the observations of the meta-analysis. Thus, IL-6 -174G>C polymorphism clearly represents a potential modulator of risk for malignant disorders with ethnicity and site dependent trends. The results also support the possibility of higher influence of inflammation related cytokine gene polymorphisms on the risk for cancers in Ancestral North Indians.

Genetic polymorphism of interleukin-6 influences susceptibility to HBV-related hepatocellular carcinoma in a male Chinese Han population

As a multifunctional cytokine, interleukin-6 (IL-6) plays a key role in chronic inflammation as well as tumor growth and progression of hepatitis B virus (HBV) infection. Recent studies have implicated that single nucleotide polymorphism (SNP) -572C>G (rs1800796) located within the promoter region of IL-6 gene was associated with susceptibility to several diseases. Here, a case-control study was undertaken to investigate the association between this polymorphism and HBV-related hepatocellular carcinoma (HCC) susceptibility in a Chinese Han population. A total of 900 patients with chronic HBV infection, including 505 HBV-related HCC patients and 395 HBV infected patients without HCC were enrolled, and rs1800796 polymorphism was genotyped by the TaqMan method and DNA sequencing technology. The results indicated no significant association between rs1800796 polymorphism and the risk of HBV-related HCC in all subjects; however, a significant difference was identified in male subjects. Under the dominant model, male subjects with the G allele (CG/GG) have higher susceptibility to HBV-related HCC than those with CC genotype after adjusting confounding factors (P=0.012, odds ratio [OR] 1.68, 95% confidence interval [95% CI] 1.15-2.42). Our results suggested that rs1800796 polymorphism of IL-6 gene was associated with susceptibility to HBV-related HCC in a male Chinese Han population.

Rather than Rs1800796 polymorphism, expression of interleukin-6 is associated with disease progression of chronic HBV infection in a Chinese Han population

Interleukin-6 plays an important role in chronic inflammation as well as tumor growth and progression. Here, a case-control study was undertaken to investigate the association of rs1800796 polymorphism of IL-6 gene and serum levels with disease progression of chronic HBV infection. Rs1800796 polymorphism was genotyped in 641 Chinese Han patients with chronic HBV infection, including 23 IT, 25 IC, 292 CHB, 153 LC, and 148 HCC patients and 265 healthy controls. Serum IL-6 levels were measured in 23 IT, 25 IC, 47 CHB, 41 LC, and 49 HCC patients and 45 healthy controls, and the classifications of HCC were accorded to BCLC staging system. We found no significant association between rs1800796 polymorphism and disease progression of chronic HBV infection; however, serum IL-6 levels showed significant statistical differences between patients with CHB, LC, and HCC. Moreover, statistical differences can be observed in patients with terminal stage HCC compared with those of early to intermediate or advanced stage HCC. Our findings suggest that rs1800796 polymorphism unlikely contribute significantly to affect the progression of chronic HBV infection, and serum IL-6 levels can act as a useful indicator for disease progression and severity of chronic HBV infection.

The association of IL-6 and IL-6R gene polymorphisms with chronic periodontitis in a Chinese population

OBJECTIVE

The aim of our investigation is to reveal the association of interleukin-6 (IL-6) and interleukin-6 receptor (IL-6R) gene polymorphisms with chronic periodontitis in Northwestern Chinese Han Population.

MATERIAL AND METHODS

A case-control study of 199 cases of chronic periodontitis patients and 216 healthy controls was performed. Genomic DNA was isolated from whole venous blood, and four single nucleotide polymorphisms (IL-6 -572 G/C and -1363 G/T, IL-6R -183 G/A and +48892 A/C) were analysed using polymerase chain reaction, followed by restriction fragment length polymorphism analysis and sequencing methods.

RESULTS

Our SNP analyses showed that the distribution of the IL-6 -572 G/C and IL-6R -183 G/A polymorphisms did not differ between patients and controls. The frequency of the IL-6 -1363 G/T genotype GG was significantly increased chronic periodontitis cases (P = 0.023, odds ratio (OR) = 2.825 adjusted for gender and age.) The IL-6R +48892 A/C polymorphisms genotype CC was found to be protective against chronic periodontitis (P = 0.004, OR = 0.318 adjusted for gender and age.). In addition, compared with the other haplotypes, haplotype A(+48892) A(-183) was significantly associated with chronic periodontitis, with an odds ratio of 0.720 (P = 0.0235).

CONCLUSION

Our results suggest that the IL-6 -1363 G/T and IL-6R +48892 A/C polymorphisms may contribute to genetic susceptibility to chronic periodontitis in Northwestern Chinese Han population.

A two-SNP IL-6 promoter haplotype is associated with increased lung cancer risk

BACKGROUND

Aberrant expression of interleukin-6 (IL-6) may play an important role in lung carcinogenesis. Whether IL-6 promoter haplotypes are associated with lung cancer risk and their functions have not yet been studied. We tested the hypothesis that single-nucleotide polymorphism (SNP) and/or haplotypes of IL-6 promoter are associated with risk of lung cancer.

METHODS

Two functional IL-6 promoter SNPs (-6331T>C and -572C>G) were genotyped in the discovery group including 622 patients and 614 controls, and the results were replicated in an independent validation group including 615 patients and 638 controls. Luciferase reporter gene assays were conducted to examine the function of IL-6 promoter haplotypes.

RESULTS

None of the functional IL-6 promoter SNPs were associated with lung cancer risk in either study. However, a two-SNP CC (-6331C and -572C) IL-6 promoter haplotype was significantly more common among cases than among controls in both groups (P = 0.031 and P = 0.035, respectively), indicating that this haplotype is associated with increased lung cancer risk {adjusted odds ratio [OR], 1.56 [95 % confidence interval (95 % CI), 1.04-2.34] and 1.51 [95 % CI, 1.03-2.22], respectively}. Combined analysis of both studies showed a strong association of this two-SNP haplotype with increased lung cancer risk (adjusted OR, 1.53; 95 % CI, 1.16-2.03; P = 0.003). Comparably, luciferase reporter assays of A549 lung cancer cell lines transfected with the CC haplotype revealed that the two-SNP haplotype had significantly higher IL-6 transcriptional activity compared with cells transfected with the common haplotype.

CONCLUSIONS

This is the first evidence of identifying an IL-6 promoter haplotype (CC) associated with increased risk of lung cancer.

Interleukin-6 -634 C/G and -174 G/C polymorphisms in Korean patients undergoing hemodialysis

BACKGROUND/AIMS

Chronic inflammatory status is a possible risk factor for vascular access dysfunction in hemodialysis (HD) patients, but susceptibility differences appear among individuals. Interleukin (IL)-6 is a well-known inflammatory cytokine with various polymorphisms. We examined whether IL-6 polymorphisms are associated with vascular access dysfunction in HD patients.

METHODS

A total of 80 HD patients (including 42 diabetic patients) were enrolled. Polymorphisms in the IL-6 gene promoter (-634 C/G and -174 G/C) were studied using restriction length polymorphism polymerase chain reaction analysis. Vascular access patency was compared between the patient groups with respect to IL-6 polymorphisms. An additional 89 healthy individuals were enrolled in the control group. Plasma IL-6 levels were determined by enzyme-linked immunosorbent assay.

RESULTS

The GG genotype and G allele at position -634 in the IL-6 promoter were more frequently observed in HD patients than in controls. Furthermore, the distribution of the -634 polymorphism differed according to vascular access patency in non-diabetic HD patients. However, the G allele was not a significant risk factor for early access failure. No significant association appeared between the IL-6 -634 C/G polymorphism and plasma IL-6 levels. The C allele of the IL-6 -174 G/C polymorphism was not detected in our study population.

CONCLUSIONS

The IL-6 -634 G allele appears with greater frequently in patients with end-stage renal disease and may be associated with vascular access dysfunction in non-diabetic HD patients.

Association of IL-1β and IL-6 gene polymorphisms with recurrent spontaneous abortion in a Chinese Han population

As certain cytokines may play a role in unexplained recurrent spontaneous abortion (RSA) and also some cytokine gene polymorphisms may affect the level of cytokine production, the aim of this study was to investigate the relationship between Chinese RSA and polymorphisms of the genes coding for interleukin (IL)-1β (-31C/T, -511C/T, +3954C/T) and IL-6 (-634C/G). Women (n = 162) with at least three consecutive spontaneous abortions and 156 ethnically matched healthy women with at least one successful pregnancy were included. Genotypes were determined using restriction fragment length polymorphism analysis of polymerase chain reaction products. No significant differences were found in the IL-1β-31T, -511T and +3954T distributions between the RSA group and the control group. On the other hand, the frequencies of the IL-6-634GG genotype and -634G allele were significantly decreased in the RSA group versus the control group (genotype: P = 0.0003; allele: P = 0.002), suggesting the IL-6-634C/G polymorphism might be a possible genetic protective factor for RSA.

Polymorphisms in interleukin-6-6331 influences the susceptibility of a Chinese population to gastric cancer

We investigated the association of Interleukin (IL)-6-6331 polymorphisms with susceptibility to gastric cancer in 375 patients with gastric cancer and 386 age- and gender-matched healthy controls. After adjustment for the potential confounding effects of gender and age, IL-6-6331TC genotype was associated with a decreased risk of gastric cancer compared with the CC genotype. Further stratification analyses indicated that the protective effect of TC genotype was also observed in poorly differentiated gastric cancer, noncardia gastric cancer, and intestinal-type gastric cancer, respectively. These results suggest that the IL-6-6331 polymorphism is involved in susceptibility to developing gastric cancer.

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

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

Interleukin 6 gene polymorphisms are associated with systemic lupus erythematosus in Koreans

OBJECTIVE

Interleukin 6 (IL-6) gene polymorphisms are known to play a role in chronic inflammatory disorders. We searched for polymorphisms in the IL-6 gene and described their pathogenic role in Korean patients with systemic lupus erythematosus (SLE).

METHODS

Genomic DNA was extracted from 151 patients with SLE and 151 controls, and about 1.4 kb-sized IL-6 genes located between promoter region and exon 2 region were amplified by polymerase chain reaction. The promoter activity was analyzed by luciferase reporter assay in Hep3B cells and HeLa cells.

RESULTS

We identified 4 single-nucleotide polymorphisms (SNP; -572 C > G, -278 A > C in the promoter, and 330 T > G, and 334 A > T in exon 2) and a -373 A(n)T(n) tract polymorphism in the IL-6 gene. The genotype frequency, -373 A(10)T(11), -278 C, and 334 T allele were significantly associated with SLE (p < 0.001, p = 0.03 and p = 0.005, respectively). Patients with SLE carrying the -572 G allele had anti-dsDNA more frequently (p = 0.007). In addition, thrombocytopenia was significantly more common in patients carrying the -278 C allele (p = 0.006). In the haplotype analysis, patients with SLE had more frequently haplotype HT3 (CA(10)T(11)ATA, dominant model, p = 0.012) that was associated with arthritis, leukopenia, anti-dsDNA, and hypocomplementemia. Promoter reporter structures carrying the -278 C allele displayed significantly higher promoter activity than the -278 A allele in Hep3B cells (p < 0.001) and HeLa cells (p < 0.001).

CONCLUSION

These data suggest that IL-6 gene polymorphisms are associated with disease susceptibility and phenotype of SLE. In addition, promoter polymorphisms may be involved in regulation of IL-6 expression.

Lack of association between the promoter polymorphisms of MMP-3 and IL-6 genes and adolescent idiopathic scoliosis: a case-control study in a Chinese Han population

STUDY DESIGN

Case-control study.

OBJECTIVE

This study is to replicate the association between the promoter polymorphisms of matrix metalloproteinase (MMP)-3 (-1171 5A/6A rs3025058) and interleukin (IL)-6 genes (-174G/C rs1800795) and adolescent idiopathic scoliosis (AIS) in a Chinese Han population.

SUMMARY OF BACKGROUND DATA

Recently, promoter polymorphisms in MMP-3 and IL-6 have been reported to be associated with AIS. Such genetic association, if confirmed by replication in other samples, would point to a primary degenerative defect in the disc or nucleus pulposus and inflammation as the key pathogenic mechanisms of AIS.

METHODS

A total of 487 Chinese girls with AIS and 494 healthy age-matched adolescent girls were recruited consecutively during a 3-year period. The same genotyping technique as the original report was used to detect promoter polymorphisms of the MMP-3 and IL-6 genes. Statistical analysis of genotype frequencies between AIS patients and normal controls were performed by chi test.

RESULTS

In this association study of the MMP-3 polymorphism and the risk of scoliosis, no significant difference was found between cases and controls, both in term of allelic association (6A: 81.2% in cases vs. 81.8% in controls, 5A: 18.8% in cases vs. 18.2% in controls, P = 0.745) or genotype association (6A/6A: 65.9% in cases vs. 66.2% in controls, 5A/6A: 30.6% in cases vs. 31.2% in controls, and 5A/5A: 3.5% in cases vs. 2.6% in controls; P = 0.733). Among AIS patients, the maximal Cobb angles were also not different among MMP-3 genotypes (6A/6A: 31.1 degrees +/- 9.7 degrees, 5A/6A: 29.1 degrees +/- 10.5 degrees, and 5A/5A: 29.4 degrees +/- 11.2 degrees; P = 0.392). As for IL-6 polymorphism, -174G/C polymorphism was not found in the Chinese AIS patients, and all 100 AIS patients and 100 normal controls were found to carry the G/G wild type.

CONCLUSION

This study did not find any significant association of promoter polymorphisms of the MMP-3 (-1171 5A/6A rs3025058) and IL-6 gene (-174G/C rs1800795) with AIS. The results indicate that the MMP-3 promoter polymorphism is not associated with AIS in the Chinese population. Further studies, however, are needed to rule out the potential association with other promoter polymorphisms in IL-6.

Polymorphism in interleukin-6 gene is associated with bone mineral density in patients with adolescent idiopathic scoliosis

Low bone mass and osteopenia have been described in the axial and peripheral skeleton of patients with adolescent idiopathic scoliosis (AIS). Recently, many studies have shown that gene polymorphism is related to osteoporosis. However, no studies have linked the association between IL6 gene polymorphism and bone mass in AIS. This study examined the association between bone mass and IL6 gene polymorphism in 198 girls with AIS. The polymorphisms of IL6-597 G→A, IL6-572 G→C and IL6-174 G→A and the bone mineral density in the lumbar spine and femoral neck were analysed and compared with their levels in healthy controls. The mean bone mineral density at both sites in patients with AIS was decreased compared with controls (p = 0.0022 and p = 0.0013, respectively). Comparison of genotype frequencies between AIS and healthy controls revealed a statistically significant difference in IL6-572 G→C polymorphism (p = 0.0305). There was a significant association between the IL6-572 G→C polymorphism and bone mineral density in the lumbar spine, with the CC genotype significantly higher with the GC (p = 0.0124) or GG (p = 0.0066) genotypes.

These results suggest that the IL6-572 G→C polymorphism is associated with bone mineral density in the lumbar spine in Korean girls with AIS.

The -174 G/C polymorphism in interleukin-6 (IL-6) promoter region is associated with serum IL-6 and carcinoembryonic antigen levels in patients with colorectal cancers in Taiwan

INTRODUCTION

We investigated the associations between -174 G/C polymorphism of interleukin-6 (IL-6) gene promoter and serum IL-6 and carcinoembryonic antigen (CEA) levels in Taiwanese patients with colorectal cancer (CRC).

RESULTS AND DISCUSSION

The frequency of the G allele was only 0.043, which is significantly lower compared to Western analogs. On grouping genotypes as G-positive (GG and CG) and G-negative (GG), the average IL-6 level and CEA levels were significantly lower in G-positive patients than in G-negative analogs (IL-6, 3.56 +/- 4.38 vs. 15.38 +/- 9.52 pg/ml, P = 0.021; CEA, 27.7 +/- 25.7 vs. 157.7 +/- 59.6 ng/ml, P = 0.012). The patients without the G allele had higher incidences of synchronous cancers of other origins (P = 0.003).

CONCLUSION

In conclusion, ethnicity affects the status of -174 G/C IL-6 polymorphism. This polymorphism status consequently influences the expressions of serum IL-6 and CEA and incidences of synchronous cancers of other origins.

Inflammation as a cardiovascular risk factor and pulse wave velocity as a marker of early-stage atherosclerosis in the Japanese population

Inflammation and pulse wave velocity (PWV) are a potential risk factor and marker, respectively, for atherosclerosis in the primary prevention setting. Atherosclerosis is now generally accepted to be an inflammatory disorder of the arterial wall, and the high-sensitivity C-reactive protein (hs-CRP) level has been reported to be a strong predictor of cardiovascular events. High-sensitivity-CRP is associated with two factors related to inflammation: (1) the local production of CRP by atheromatous tissue or coronary artery smooth muscle cells and (2) adipose tissue as a potent source of inflammatory cytokines. Based on studies in North America and Europe, hs-CRP has been established as a cardiovascular risk factor and a cut-off value has been recommended. However, Japanese have lower hs-CRP values than their Western counterparts, partly because Japanese have a lower body mass index (BMI), which correlates positively to hs-CRP, and partly because lifestyle and genetic factors can affect hs-CRP values. Therefore, a cut-off value needs to be established by cohort studies for the Japanese population. Carotid-femoral PWV is most commonly measured by applanation tonometry, particularly in Europe, but this method is critically dependent upon the accurate placing of transducers over the arteries and is both time-consuming and complex. A novel device has been recently developed in Japan that measures brachial-ankle PWV (baPWV) using a volume-rendering method. Brachian-ankle PWV is a suitable screening method because of its technical simplicity and shorter measurement time. It is associated not only with conventional cardiovascular risk factors but also with new risk factors, such as inflammation, gamma-glutamyltransferase, chronic kidney disease, and psychosocial factors. However, a suitable cut-off value has yet to be established.

Relationship between single nucleotide polymorphisms in -174G/C and -634C/G promoter region of interleukin-6 and prostate cancer

The association between the single nucleotide polymorphisms (SNPs) in -174G/C and -634C/G of interleukin-6 (IL-6) promoter region and prostate cancer was examined in the population of Han people in Hubei region. TaqMan PCR was employed for the gene-typing of -174G/C and -634C/G in promoter region of IL-6 gene to compare the prostate cancer patients and normal controls in terms of genotype frequency, allele frequency and risk of prostate cancer. Enzyme-linked immunosorbent assay (ELISA) was used for the detection of IL-6 concentration in peripheral blood of the patients with prostate cancer and the relationship between the IL-6 level and the genotype was studied. Our results showed that in all the subjects, the genotype of genetic locus -174G/C was found to be GG and no CG and CC were observed. There was a significant difference in gene frequency of GG, CG and CC of -634C/G and allele frequency of G and C between prostate cancer patients and normal controls (P<0.05) and the gene frequency of GG+CG increased with the clinical stages and pathological grades of prostate cancer. The IL-6 level in GG+CG group was significantly higher than that in CC group. It was concluded that no SNP in -174G/C IL-6 promoter region was found in the population of Han people in Hubei region. The SNP in -634C/G was, to some extent, associated with the development and progression of prostate cancer. The population with GG+CG genetype has higher risk for prostate cancer.

Interactions of interleukin-6 gene polymorphisms with calcium intake and physical activity on bone mass in pre-menarche Chinese girls

This study assessed independent associations and interactions of IL-6 promoter alleles (-174G/C and -634C/G), calcium intake and physical activity with bone mass among pre-menarche Chinese girls. The -634 CC carriers, greater calcium intake and physical activity were associated with better bone mass. The gene-bone association was more pronounced among girls with high physical activity or with low calcium intake.

INTRODUCTION

The association between interleukin (IL)-6 promoter polymorphisms and bone mass remains in debate. This cross-sectional study examined the association between the IL-6 promoter alleles (-174G/C and -634C/G) and bone mass, and assessed if the association could be modified by calcium intake or physical activity in pre-menarche Chinese girls.

METHODS

Two-hundred and twenty-eight healthy pre-menarche girls aged 9-11 years were recruited from primary schools in Guangzhou, China by sending letters to parents. None of them had diseases or medications known to affect bone metabolism. The IL-6 promoter genotypes were determined by PCR-RFLP, and BMD and BMC at the total body, lumbar spine, total hip and femoral neck were measured by DXA. Calcium intake and physical activity were assessed by face-to-face questionnaire interview.

RESULTS

One hundred and seventy-six subjects completed the entire study. We did not detect gene polymorphism at the IL-6 -174G/C locus, all were GG homozygotes. The IL-6 -634C/G polymorphism was significantly associated with both BMD and BMC even after adjusting for age and weight. Girls with CC genotype had higher levels of BMC and BMD than G allele carriers (+8.3% for the total body BMC, and +2.9%, +5.8%, and +5.7% for BMDs at the total body, total hip, and femoral neck, respectively; P < 0.05). The favorable effect of physical activity on BMDs at the total hip and femoral neck was much more pronounced in CC carriers than in G allele carriers, and the CC genotype associated higher BMDs at the total hip and femoral neck were observed only in girls with high level physical activity (P for interactions = 0.036 and 0.021, adjusted for age and weight). Calcium had a more benefit to the total body BMC in G allele carriers than in CC carriers, and the G allele-associated lower total body BMC was found only in subjects with low calcium intake.

CONCLUSION

The IL-6 -634C/G polymorphism was significantly associated with BMD and the association might be modified by calcium intake or physical activity in pre-menarche Chinese girls.

Cytokine gene polymorphisms in recurrent spontaneous abortions: a comprehensive review

PROBLEM

Cytokine gene polymorphism studies in women with recurrent spontaneous abortion (RSA) are reviewed to provide comprehensive understanding and a direction for the future investigation.

METHOD OF STUDY

A search of PubMed was made to identify the published data between 2001 and 2007 regarding RSA and cytokine gene polymorphisms.

RESULTS

Either allele and/or genotype frequencies of the following polymorphisms were reported to be significantly different between women with RSA and controls: IFN-gamma +874A-->T, TA (P = 0.01), AA (P = 0.04); IL-6, -634C-->G CG/GG (P = 0.026); IL-10, -592C-->A CC (P = 0.016); IL-1B -511C (P = 0.035), -31T (P = 0.029); IL-1RA, IL1RN*2 (P = 0.002), and IL1RN*3 (P = 0.002). None of these studies was repeatedly reported by others to be significantly different. Among these, four cytokine polymorphisms (IFN-gamma, +874A-->T; IL-1B -511C; IL-1RA, IL1RN*2, IL1RN*3) were refuted by others and rest of them were studied once.

CONCLUSION

Multiple cytokine polymorphisms were reported to be associated with RSA. However, a majority of studies were not confirmed by other investigators or refuted by others. Inconsistent study results might be related to: (i) the production of these cytokines is partly under genetic controls and other factors affect cytokine levels; (ii) ethnic background, environmental factors, and selection criteria for study populations are different and (iii) the possibilities exist that multiple cytokine gene polymorphisms or other genes in linkage disequilibrium may play a role in RSA.

The interleukin-6 gene -572G>C promoter polymorphism is related to intracranial aneurysms in Chinese Han nationality

There is evidence suggesting that inflammation plays an important role in the pathogenesis of intracranial aneurysms (IAs). Interleukin-6 (IL-6) is an important pro-inflammatory cytokine, and some authors have demonstrated that IL-6 promoter polymorphism -572G>C is associated with IAs in Caucasian population. We performed a case-control study to investigate whether this single nucleotide polymorphism (SNP) might affect the development of IAs in Chinese Han population. The study groups comprised 240 Chinese Han nationality aneurysmal patients and 240 controls. Differences in genotype and allele frequencies between patients and controls were tested by the chi-square method. The results showed that among the Chinese Han subjects, there were significant differences in genotypic distribution and allele frequencies between aneurysmal patients and controls. The GG genotype was significantly more common in patients than in controls (24.5% vs. 3.7%, p<0.001, odds ratio 8.366, 95% CI: 4.040-17.324), and the G allele was much more frequent in patients than in controls (51.7% vs. 20.8%, p<0.001, odds ratio 4.062, 95% CI: 3.058-5.395).

Serum interleukin-6 level but not genotype predicts survival after resection in stages II and III gastric carcinoma

PURPOSE

It has been suggested that interleukin-6 (IL-6) is a prognostic indicator for survival in patients with gastric carcinoma, but this has not been proved using survival analysis. In Asians, the -634G allele is associated with increased IL-6 production. The objective of this study was to evaluate the association between serum IL-6 levels, -634G/C polymorphism, and overall survival after resection for gastric carcinoma.

EXPERIMENTAL DESIGN

A total of 155 consecutive patients with gastric carcinoma were evaluated. Serum IL-6 levels were analyzed using an enzyme-linked immunoabsorbent assay. Genotype was determined by PCR and restriction fragment length polymorphism. Serum levels and survival were correlated with genotype and clinicopathologic factors.

RESULTS

Age and stage, but not -634G/C genotype, were associated with serum IL-6 levels. The median survival for patients with stage II or stage III gastric carcinoma was 1,418 days in patients with low (< or =13 pg/mL) versus 618 days in patients with high (>13 pg/mL) serum IL-6 levels (P = 0.038). Results of a multivariate analysis showed that serum IL-6 level of >13 pg/mL was a significant predictor of poor survival (hazard ratio, 1.77; 95% confidence interval, 1.07-2.92; P = 0.026).

CONCLUSIONS

Serum IL-6 level of >13 pg/mL correlates with tumor progression and is an independent predictor of poor survival after resection. In patients with stage II and III gastric carcinoma, serum IL-6 level is more effective than stage as a prognostic indicator. By measuring IL-6, these patients can be divided into two groups with significant differences in survival. The -634G/C polymorphism is not associated with serum IL-6 level or survival.

Interaction of interleukin-6 and estrogen receptor gene polymorphisms on bone mass accrual in Chinese adolescent girls

We assessed the main and interaction effects of interleukin-6 and estrogen receptor gene polymorphisms on bone mass accrual in Chinese adolescent girls. A total of 228 premenarche Chinese girls (9-11.5 years old) were recruited for a 2-year follow-up study. Bone mineral density (BMD) at the total body, lumbar spine (L1-L4), and total left hip were measured by dual-energy X-ray absorptiometry at baseline and follow-up. The -174G/C and -634C/G polymorphism of IL-6 gene, and PvuII and XbaI polymorphisms of the estrogen receptor (ER)-alpha gene, were determined. The -634C/G polymorphism of the IL-6 gene and PvuII polymorphism of ER-alpha gene were significantly associated with bone mass accrual after adjusting the potential confounding factors. Girls with pp genotype of ER-alpha gene had greater percentage accrual in BMD of total body (P = 0.010) and femoral intertrochanter (P = 0.038) than their PP and Pp counterparts. Girls with CC genotype of IL-6 -634G/C gene had higher percentage accrual in BMD of total body (P = 0.032) and femoral trochanter (P = 0.048) than their CG + GG counterparts. Significant interaction effects of IL-6 -634C/G polymorphism and ER-alpha PvuII polymorphism were observed on percentage change in BMD of total left hip (P = 0.009) and femoral intertrochanter (P = 0.007). The genotype CC (IL-6 -634C/G) x pp (ER-alpha PvuII) was associated with greater BMD accrual than other genotype combination in Chinese adolescent girls. We found that the IL-6 -634C/G and ER-alpha PvuII polymorphism were significantly associated with BMD accrual and that they have an interactional effect on BMD accrual in Chinese adolescent girls.

No association of interleukin-6 gene polymorphism (-174 G/C) with premature coronary artery disease in a Turkish cohort

OBJECTIVES

Interleukin-6 (IL-6) may contribute to the inflammatory response by activating endothelial cells and stimulating the synthesis of fibrinogen. It might thus be important in the pathogenesis of inflammation associated with coronary artery disease (CAD). Several studies suggested that the -174 C allele was associated with an increased prevalence of coronary heart disease. The aim of this study was to investigate further the association of the IL-6 -174 G/C allele status with premature CAD.

METHODS

A total of 120 patients and 105 controls were included in the study. The IL-6 -174 G/C polymorphism was genotyped using PCR-restriction fragment length polymorphism.

RESULTS

The genotype distribution of the -174 G/C polymorphism was not different in premature CAD patients (GG: 53%; GC: 42.6%; CC: 4.3%) and controls (GG: 54.3%; GC: 39%; CC: 6.7%) (P=0.72). The prevalence of the C allele was 25.6% in patients and 26.1% in controls. By multiple regression analysis, family history, smoking, diabetes, and hypertension were independent risk factors of premature CAD, but not IL-6 genotype.

CONCLUSIONS

We conclude that the IL-6 -174 G/C polymorphism is not associated with the risk of premature CAD, and does not contribute to cardiovascular risk stratification.

Influence of the -308 TNF-alpha and -174 IL-6 polymorphisms on lipid profile in Mexican subjects

Polymorphisms in the promoter region of several cytokine genes have been associated with differential cytokine production. Several reports indicate that polymorphisms in the tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) genes are associated with lipid abnormalities. The aim of this study was to identify the genotype frequencies for -308G/ATNF-alpha and -174G/CIL-6 polymorphisms in Mexican subjects and to determine the influence of both polymorphisms on serum lipid levels. Serum lipid concentrations were measured in 100 healthy Mexican subjects. Screening of the -308G/ATNF-alpha and -174G/CIL-6 polymorphisms was performed in all participants using PCR-RFLPs. Genotype frequency for TNF-alpha polymorphism was: 87% GG and 13% GA, whereas IL-6 polymorphism was: 77% GG and 23% GC. The polymorphism frequencies obtained in this study were significantly different to Caucasian populations. High serum levels of triglycerides and total cholesterol were associated with GG genotype of the -308 TNF-alpha polymorphism, as well as low HDL-c levels, but no association was found between the -174 IL-6 polymorphism and serum lipid concentrations. We observed a significant association of the -308 TNF-alpha polymorphism with lipid profile in Mexican subjects. Furthermore, the genotype distribution of -308 TNF-alpha and -174 IL-6 polymorphisms in Mexican Mestizo population similar to populations in different continents may be due to our genetic background influenced by the mixture of Spaniards, Indian and black genes.

Frequency distribution of cytokine gene polymorphisms in the healthy North Indian population

The allelic and genotype frequencies corresponding to 22 single nucleotide polymorphisms (SNPs) in 13 cytokine genes interleukin (IL) 1-alpha (T/C -889), IL1-beta (C/T -511, T/C +3962), IL12 (C/A -1188), interferon-gamma (A/T UTR 5644), transforming growth factor-beta (C/T codon 10, G/C codon 25), tumour necrosis factor-alpha (G/A -308, G/A -238), IL2 (T/G -330, G/T +160), IL4 (T/G -1098, T/C -590, T/C -33), IL6 (G/C -174, G/A nt 565), IL10 (G/A -1082, C/T -819, C/A -592), IL1R (C/T pst11970), IL1RA (T/C mspa111100) and IL4RA (G/A +1902) were determined in 130 healthy North Indian subjects. All genomic typings were performed with polymerase chain reaction with sequence-specific assays. An analysis of the allelic and haplotype frequencies in the North Indian population showed a good fit with the Hardy-Weinberg equilibrium for most of the SNPs. The data can be used for anthropological comparisons, as well as for association studies with different diseases and for use in transplant situations involving acute and chronic rejection.

Effects of the Interaction between Interleukin-6-634C/G Polymorphism and Smoking on Serum C-Reactive Protein Concentrations

Smoking and interleukin-6 (IL-6) are major factors in inflammation. The aim of this study was to investigate whether or not the IL6 -634C/G polymorphism (rs1800796) and its interaction with smoking influence serum C-reactive protein (CRP) concentrations. The subjects were 347 Japanese male employees of a transit company. CRP and conventional cardiovascular risk factors were evaluated. IL6 -634C/G polymorphisms were genotyped by allelic discrimination using fluorogenic probes and the 5' nuclease assay. The mean values of CRP were significantly higher in current smokers than in nonsmokers after adjustment for age, body mass index (BMI), systolic blood pressure, total cholesterol, log triglycerides, high-density lipoprotein cholesterol (HDL-C), fasting glucose, and drinking habit (p=0.011). Comparison of three genotypes revealed significant interaction between smoking and the IL6 -634C/G genotype manifested by CRP concentrations (p=0.007) after the adjustments cited above. After stratification by smoking status, CRP differed significantly among IL6 -634C/G genotypes groups in nonsmokers (p=0.010, p for trend=0.007), whereas no significant difference was found in current smokers. Comparison between -634C/C and C/G+G/G groups revealed also a significant interaction between smoking and the IL6 -634C/G genotype (p=0.007). These findings suggest that the impact of the -634G allele on CRP elevation is greater in nonsmokers than in current smokers. Since gene-environment interactions have been insufficiently examined, further studies are required to clarify their effect on inflammation, including CRP elevation.