Association between G-308A polymorphism of the tumor necrosis factor-alpha gene and 24-hour ambulatory blood pressure values in type 1 diabetic adolescents

Association of tumor necrosis factor-α -308 G/A gene polymorphism with coronary artery diseases: An evidence-based study

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death worldwide and remains a major health problem, providing the rationale for identification of molecular markers for detection of individuals at high risk of developing CAD. Tumor necrosis factor-α (TNF-α) plays a crucial role in the pathogenesis of CAD. We have therefore explored the association of TNF-α 308 (G/A) gene polymorphism in 903 individuals with/without CAD.

METHODS

TNF-α 308 gene polymorphism was analyzed in 903 subjects of whom 222 were healthy controls. Among the 681 patients who were investigated angiographically, 468 had ≧50% stenosis and 213 patients had <50% stenosis. Biochemical profiles (eg, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting blood glucose, and CRP) were evaluated. Associations between TNF-α genotypes with biochemical and anthropometric characteristics were determined.

RESULTS

The frequencies of TNF-α-AA or AG genotypes were significantly lower in patients classified as CAD patients with ≥ or <50% obstruction in at least one coronary artery, compared to the control group. We observed that CAD patients with ≥50% stenosis and with AA genotype were associated with higher risk of CAD with OR of 3.56 (95%CI: 1.02-12.41; P=.046) using multivariate analysis. Moreover, we found that TNF-α-308-AA genotype was associated with blood pressure and CRP level in CAD patients, compared to the wild type-genotype.

CONCLUSION

Our data showed an association of TNF-α-308G/A polymorphism with CAD patients with ≥50% obstruction, supporting the need for further investigations on the role of TNF-α-308G/A polymorphism with hypertension.

Associations between TNF gene polymorphisms (-308 A/G, -238 A/G, -1031 C/T and -857 T/C) and genetic susceptibility to T1D: a meta-analysis

The aim of this study was to estimate the associations between tumor necrosis factor (TNF) gene polymorphisms and type 1 diabetes (T1D) using meta-analysis. Relevant studies were searched using PubMed and Embase up to August 2013. A total of 32 comparisons from 21 studies examining the associations between TNF polymorphisms and T1D were included in the present meta-analysis. Our meta-analysis identified a significant association between TNF -308 A/G polymorphism A allele and T1D in all subjects [odds ratio (OR) 2.001, 95 % confidence interval (CI) 1.732-2.312). Significant associations of AA and AA+AG genotype of TNF -308 A/G polymorphism with genetic susceptibility to T1D were also found (OR 3.203, 95 % CI 2.373-4.324; OR 2.232, 95 % CI 1.881-2.649). After stratification by ethnicity, significant associations of T1D with TNF -308 A/G polymorphism under all genetic models (A allele and AA, AA+AG genotype) were still detected in European (OR 1.952, 95 % CI 1.675-2.274; OR 3.108, 95 % CI 2.169-4.455; OR 2.249, 95 % CI 1.870-2.706, respectively) and non-European populations (OR 2.152, 95 % CI 1.488-3.112; OR 3.439, 95 % CI 2.000-5.914; OR 2.207, 95 % CI 1.496-3.257, respectively). Our meta-analysis also revealed an association of TNF -857 T/C polymorphism T allele with T1D risk (OR 1.647, 95 % CI 1.431-1.896). Furthermore, analysis of TT and TT+TC genotype indicated the same result patterns as shown by the TNF -857 T/C polymorphism T allele (OR 2.206, 95 % CI 1.467-3.317; OR 1.762, 95 % CI 1.490-2.083). In conclusion, our meta-analysis results indicate that TNF -308 A/G and -857 T/C polymorphisms are involved in the genetic background of T1D.

Tumor necrosis factor-alpha g308α gene polymorphism and essential hypertension: a meta-analysis involving 2244 participants

Background

The tumor necrosis factor-alpha (TNFα) G308A gene polymorphism has been implicated in susceptibility to essential hypertension (EH), but study results are still controversial.

Objective and Methods

The present meta-analysis is performed to investigate the relationship between the TNFα G308A gene polymorphism and EH. Electronic databases were searched and seven separate studies on the association of the TNF α G308A gene polymorphism with EH were analyzed. The meta-analysis involved 1092 EH patients and 1152 controls. The pooled odds ratios (ORs) and their corresponding 95% confidence interval (CI) were calculated by a fixed or random effect model.

Results

A significant relationship between the TNFα G308A gene polymorphism and EH was found in an allelic genetic model (OR: 1.45, 95% CI: 1.17 to 1.80, P = 0.0008), a recessive genetic model (OR: 3.181, 95% CI: 1.204 to 8.408, P = 0.02), and a homozygote model (OR: 3.454, 95% CI: 1.286 to 9.278, P = 0.014). No significant association between them was detected in both a dominant genetic model (OR: 1.55, 95% CI: 0.99 to 2.42, P = 0.06) or a heterozygote genetic model (OR: 1.45, 95% CI: 0.90 to 2.33, P = 0.13).

Conclusion

The TNFα G308A gene polymorphism is associated with EH susceptibility.

Tumour necrosis factor gene polymorphism and disease prevalence

Tumour necrosis factor (TNF), an important proinflammatory cytokine, plays a role in the regulation of cell differentiation, proliferation and death, as well as in inflammation, innate and adaptive immune responses, and also implicated in a wide variety of human diseases. The presence of DNA sequence variations in regulatory region might interfere with transcription of TNF gene, influencing the circulating level of TNF and thus increases the susceptibility to human diseases (infectious, cancer, autoimmune, neurodegenerative and other diseases). In this review, we have comprehensively analysed various published case-control studies of different types of human diseases, in which TNF gene polymorphism played a role, and computationally predicted several single nucleotide polymorphisms (SNPs) lie in transcription factor-binding sites (TFBS) of transcription factors (TFs). It has been observed that TNF enhancer polymorphism is implicated in several diseases, and TNF rs1800629 and rs361525 SNPs are the most important in human disease susceptibility as these might influence the transcription of TNF gene. Thirty-two SNPs lies in TFBS of 20 TFs have been detected in the TNF upstream region. It has been found that TNF enhancer polymorphism influences the serum level of TNF in different human diseases and thus affects the susceptibility to diseases. The presence of DNA sequence variation in TNF gene causes the modification of transcriptional regulation and thus responsible for association of susceptibility/resistance with human diseases.

Polymorphisms in the genes encoding TGF-beta1, TNF-alpha, and IL-6 show association with type 1 diabetes mellitus in the Slovak population

Numerous cytokines have been shown to participate in the pathogenesis of type 1 diabetes (T1D). As gene polymorphisms can influence cytokine production or function, they may potentially contribute to genetic predisposition to the disease. The aim of this study was therefore to investigate the role of 22 single nucleotide polymorphisms (SNPs) in 13 cytokine and cytokine receptor genes in genetic susceptibility to T1D. Polymerase chain reaction with sequence-specific primers was used to genotype cytokine SNPs and HLA-DRB1 alleles in 151 diabetics and 140 healthy individuals of Slovak origin. Univariate analysis showed that transforming growth factor (TGF)-beta1 codon 10 TT homozygotes were significantly more susceptible to developing T1D than C allele carriers (P (c) = 0.0066, OR = 2.46). Furthermore, tumor necrosis factor (TNF)-alpha -308 A allele carriers were also significantly overrepresented among the diabetics (P (c) = 0.0031, OR = 2.62); however, the association of the -308 A allele with T1D might be due to its strong linkage disequilibrium with the susceptibility allele HLA-DRB1*0301. An association was also found with interleukin (IL)-6 -174 G/C and nt565 G/A SNPs; however, its significance was lost when statistical correction was applied. These data suggest that the TGF-beta1 codon 10 SNP is among numerous genetic variations with small individual effects on T1D development. Moreover, a possible role of TNF-alpha and IL-6 SNPs cannot be ruled out, although their association with T1D was due to strong LD with the HLA class II susceptibility allele or did not withstand statistical correction, respectively.

Family-based analysis of tumor necrosis factor and lymphotoxin-alpha tag polymorphisms with type 1 diabetes in the population of South Croatia

Tumor necrosis factor (TNF) and lymphotoxin-alpha (LTA) are cytokines with a wide range of inflammatory and immunomodulatory activities. Type 1 diabetes is an autoimmune disease characterized by destruction of insulin-producing pancreatic beta cells. The aim of the present study was to evaluate the association of polymorphisms in the TNF/LTA gene region with susceptibility to type 1 diabetes. We investigated 11 TNF/LTA tag polymorphisms, designed to capture the majority of common variation in the region, in 160 trio families from South Croatia. We observed overtransmission of alleles from parents to affected child at five variants: (rs909253, allele C, p = 1.2x10(-4); rs1041981, allele A, p = 1.1x10(-4); rs1800629 (G-308A), allele A, p = 1.2x10(-4); rs361525 (G-238A), allele G, p = 8.2x10(-3) and rs3093668, allele G, p = 0.014). We also identified overtransmission of the rs1800629(G-308A)-rs361525(G-238A) A-G haplotype, p = 2.384x10(-5). The present study found an association of the TNF/LTA gene region with type 1 diabetes. A careful assessment of TNF/LTA variants adjusted for linkage disequilibrium with HLA loci is needed to further clarify the role of these genes in type 1 diabetes susceptibility in the population of South Croatia.

Association and interaction of the TNF-alpha gene with other pro- and anti-inflammatory cytokine genes and HLA genes in patients with type 1 diabetes from North India

Type 1 diabetes (T1D) is a multifactorial autoimmune disorder where major histocompatibility complex (MHC) genes and the insulin-linked polymorphic region have been shown to play major roles. We report here an integrated effect of tumor necrosis factor (TNF) alpha with other cytokine genes. The TNF-alpha-308 GA and AA (high secretor) polymorphisms were significantly increased in the patients with T1D (n = 235) [P < 7 x 10(-6), odds ratio (OR) = 3.04, 95% confidence interval (CI) = 1.8-5.3] compared with the controls (n= 128). The variants of interferon-gamma (IFN-gamma) (A(+874)T), interleukin (IL)-6 (G(-174)C), IL-10 (A(-1082)G, T(-819)C, C(-592)A) and transforming growth factor (TGF) beta1 (T(cdn10)C, G(cdn25)C) did not show a significant difference between patients and controls. However, simultaneous presence of TNF-alpha-308 GA+AA along with both high and low secretor genotypes of IFN-gamma (P < 0.003) was significantly increased in patients. Simultaneous presence of TNF-alpha-308 GA + AA along with high secretor genotypes of IL-6 (P < 0.0001, OR = 2.61, 95% CI = 1.5-4.56), IL-10 (P < 0.0001, OR = 4.26, 95% CI = 1.9-10.1) and TGF-beta1 (P < 0.00004, OR = 2.8, 95% CI = 1.6-4.86) was also significantly increased in patients with T1D. Low secretor genotype of TNF-alpha-308 GG along with low secretor genotypes of IFN-gamma (P < 0.001, OR = 0.465, 95% CI = 0.28-0.77), high secretor genotypes of IL-6 (P < 0.000004, OR = 0.76, 95% CI = 0.227-0.621) and TGF-beta1 (P < 0.000006, OR = 0.336, 95% CI = 0.198-0.568) was protective. The TNF-alpha-308 G allele was in linkage disequilibrium (LD) with the human leukocyte antigen (HLA)-B*0801-DRB1*0301 haplotype, while TNF-alpha-308 A allele was in LD with the HLA-B*5001-DRB1*0301 and B*5801-DRB1*0301 haplotypes, suggesting that the effect of TNF-alpha -308 A allele is not because of its being in LD with any HLA alleles, but because of its functional role and its integrated effect with other cytokines.

Tumor necrosis factor-alpha -308G>A allelic variant modulates iron accumulation in patients with hereditary hemochromatosis

BACKGROUND

In vitro and animal studies suggest that tumor necrosis factor alpha (TNF-alpha) modulates intestinal iron transport. We hypothesized that the effect of TNF-alpha might be particularly relevant if iron absorption is not effectively controlled by the HFE gene.

METHODS

In patients with homozygous C282Y hemochromatosis, we investigated the influence of TNF-alpha -308G>A allelic variant on total body iron overload, determined in all patients by measuring iron removed during depletion therapy, and hepatic iron index and need for phlebotomy to prevent iron reaccumulation, measured in patient subgroups.

RESULTS

Of 86 patients with hereditary hemochromatosis, 16 (19%) were heterozygous carriers and 1 (1%) was a homozygous carrier of the TNF-alpha promoter -308A allele. Mean (SD) total body iron overload was increased 2-fold in TNF-alpha -308A allele carriers [10.9 (7.6) g] compared with homozygous carriers of the G allele [5.6 (5.0) g, P<0.001]. Hepatic iron index differed markedly between TNF-alpha -308A allele carriers [5.6 (3.5) micromol/g/year] and homozygous G allele carriers [3.1 (2.2) micromol/g/year, P=0.040, n=30]. After iron depletion, the need for phlebotomy to prevent iron reaccumulation (maintenance therapy) was substantially higher in TNF-alpha -308A allele carriers than in homozygous G allele carriers (P=0.014, n=73). We used multiple regression analyses to exclude possible confounding effects of sex, age, family screening, body-mass index, and meat or alcohol intake.

CONCLUSION

TNF-alpha -308G>A allelic variant modulates iron accumulation in patients with hereditary (homozygous C282Y) hemochromatosis, but the effect of the TNF-alpha -308A allele on clinical manifestations of hemochromatosis was less accentuated than expected from the increased iron load associated with this allele.