Frequencies of the tumor necrosis factor gene polymorphisms in the Korean population

Genetic Distribution of the LTA +252 A>G and TNFA -308 G > A Polymorphisms in the Moroccan Population

Introduction: The LTA and TNFA genes encode key proinflammatory cytokines with diverse activities in the immune responses. Single nucleotide polymorphisms (SNPs) in the LTA rs909253 (+252 A > G) and TNFA rs1800629 (-308 G > A) genes have been associated with susceptibility to many complex diseases. The aim of this study was to assess the frequency for these two key polymorphisms in the Moroccan population. Materials and Methods: A total of 338 unrelated healthy Moroccan subjects were genotyped for the two alleles using a restriction fragment length polymorphism-polymerase chain reaction method. Results: The LTA (+252 A > G) and TNFA (-308 G > A) were the most common alleles with 67.9% and 74.8% frequencies, respectively. In addition to the linkage disequilibrium between the two SNPs, significant differences in allele frequencies were observed in Moroccan population compared with Mediterraneans, Europeans, Africans, South Americans, and Asians (p < 0.05). Finally, genetic proximities between Moroccan, European, and West African populations were found by means of the principal component analysis. Conclusion: The LTA +252 A>G and TNFA -308 G > A polymorphisms among Moroccan population follow the patterns commonly encountered in other Mediterranean, European, and African populations. The result of this study could contribute in developing a genetic database on the healthy Moroccan population.

The A allele of cluster of differentiation 36 (CD36) SNP 1761667 associates with decreased lipid taste perception in obese Tunisian women

Recent studies have suggested that excessive intake of dietary fat is associated with obesity. Some obese subjects have been reported to exhibit high thresholds for the gustatory detection of lipids via lipid receptors, such as cluster of differentiation 36 (CD36). We studied lingual detection thresholds for emulsions containing oleic acid in obese Tunisian women (n 203) using a three-alternative forced choice (3-AFC) method. Genotyping of the TNF-α (rs1800629), IL-6 (rs1800795) and CD36 (rs1761667) genes was performed to associate with lipid taste perception thresholds. The CD36 genotype distribution was as follows: GG (n 42), AG (n 102) and AA (n 59). Women with the CD36 GG genotype exhibited oral detection thresholds for oleic acid that were more than three times lower than those with the CD36 AA genotype. The present study confirms a high threshold of gustatory fat detection in obese women with the CD36 AA genotype, but there is no significant association with the IL-6 and TNF-α gene polymorphisms.

Associations of the TNF-alpha -308 G/A, IL6 -174 G/C and AdipoQ 45 T/G polymorphisms with inflammatory and metabolic responses to lifestyle intervention in Brazilians at high cardiometabolic risk

BACKGROUND

Cytokines secreted by the adipose tissue influence inflammation and insulin sensitivity, and lead to metabolic disturbances. How certain single-nucleotide polymorphisms (SNPs) interfere on lifestyle interventions is unclear. We assessed associations of selected SNPs with changes induced by a lifestyle intervention.

METHODS

This 9-month intervention on diet and physical activity included 180 Brazilians at high cardiometabolic risk, genotyped for the TNF-α -308 G/A, IL-6 -174 G/C and AdipoQ 45 T/G SNPs. Changes in metabolic and inflammatory variables were analyzed according to these SNPs. Individuals with at least one variant allele were grouped and compared with those with the reference genotype.

RESULTS

In the entire sample (66.7% women; mean age 56.5 ± 11.6 years), intervention resulted in lower energy intake, higher physical activity, and improvement in anthropometry, plasma glucose, HOMA-IR, lipid profile and inflammatory markers, except for IL-6 concentrations. After intervention, only variant allele carriers of the TNF-α -308 G/A decreased plasma glucose, after adjusting for age and gender (OR 2.96, p = 0.025). Regarding the IL6 -174 G/C SNP, carriers of the variant allele had a better response of lipid profile and adiponectin concentration, but only the reference genotype group decreased plasma glucose. In contrast to individuals with the reference genotype, carriers of variant allele of AdipoQ 45 T/G SNP did not change plasma glucose, apolipoprotein B, HDL-c and adiponectin concentrations in response to intervention.

CONCLUSION

The TNFα -308 G/A SNP may predispose a better response of glucose metabolism to lifestyle intervention. The IL-6 -174 G/C SNP may confer a beneficial effect on lipid but not on glucose metabolism. Our findings reinforce unfavorable effects of the AdipoQ 45 T/G SNP in lipid profile and glucose metabolism after intervention in Brazilians at cardiometabolic risk. Further studies are needed to direct lifestyle intervention to subsets of individuals at cardiometabolic risk.

Lymphotoxin-α 252 A>G polymorphism: a link between disease susceptibility and dyslipidemia in rheumatoid arthritis?

OBJECTIVE

Rheumatoid arthritis (RA) is associated with higher levels of inflammatory mediators and with a more atherogenic lipid profile. Dyslipidemia can be present years before arthritis develops. Lymphotoxin-α (LTA) is a cytokine that mediates proinflammatory responses while also participating in lipid homeostasis, and its transcriptional activity is in part genetically determined. We examined the role of the single-nucleotide polymorphism at position 252 of the LTA gene in the genetic background of RA and dyslipidemia.

METHODS

The association between the LTA 252 A>G polymorphism and disease status was examined in a nested case-control study of 388 patients with RA and 269 unrelated healthy controls, all white. Demographics and disease features were assessed, fasting lipids measured, and the use of lipid-lowering agents evaluated.

RESULTS

The LTA 252 A allele was more frequent in cases compared to controls (70.5% and 64.3%, respectively; p = 0.018, OR 1.325, 95% CI 1.049-1.675), as well as the A/A genotype (50.8% vs 43.5%; p = 0.025). The A/A genotype was independently associated with dyslipidemia in patients, but not in controls. Patients with RA who had the LTA 252 G/G genotype were younger at disease onset and had higher C-reactive protein (CRP) levels.

CONCLUSION

We found the LTA 252 A allele to be associated with an increased risk for developing RA in whites. The LTA 252 A/A genotype translates to a phenotype more prone to dyslipidemia, and the G/G genotype to a phenotype with earlier onset of disease and higher levels of CRP, when RA does occur. These observations highlight a possible common genetic predisposition to RA and dyslipidemia.

Is there a genetic variation association in the IL-10 and TNF alpha promoter gene with gestational diabetes mellitus?

Gestational diabetes mellitus (GDM), defined as carbohydrate intolerance diagnosed for the first time during pregnancy, affects both maternal and fetal health. Possession of a specific genetic polymorphism can be a predisposing factor for susceptibility to some diseases. The aim of this study was to investigate the association between single nucleotide polymorphisms (SNP) in the promoter gene of interleukin-10 (IL-10) as well as tumor necrosis factor-alpha (TNF alpha) with the development of GDM. Two hundred and twelve consecutive series of eligible normal pregnant women (controls) and gestational diabetes mellitus women were selected based on the study's inclusion and exclusion criteria. DNA was extracted from blood and genotyped for IL-10 at three positions and TNF alpha for gene polymorphism using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Plasma levels of IL-10 and TNF alpha at different gestational periods as well as postpartum were quantified using enzyme linked immunosorbent assay (ELISA). The results of the study showed that the difference in the frequency of SNP at position -597 in the promoter of the human IL-10 gene between the control and GDM groups was statistically significant (p < 0.05). In contrast, there was no significant difference in the frequency of SNP at the other two sites in the promoter region of the human IL-10 gene (-824 and -1082) as well as position -308 in the promoter of the human TNF-alpha (p > 0.05). In addition, there was no significant difference between the two groups in terms of plasma levels of IL-10 as well as TNF alpha in different stages of pregnancy. SNP at position -597 was significantly associated with the development of GDM and shows potential for use as a predictive marker for GDM.

Association between polymorphisms in human tumor necrosis factor-alpha (--308) and -beta (252) genes and development of gestational diabetes mellitus

OBJECTIVE

The aim of this study is to investigate if an association exists between single nucleotide polymorphism (SNP) in the tumor necrosis factor-alpha (TNF-alpha) and TNF-beta genes.

METHODS

The DNA was extracted and SNP in the human TNF-alpha and TNF-beta genes at positions -308 (G/A) and 252 (A/G), respectively, was analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Plasma levels of TNF-alpha in different stages of pregnancy were quantified using enzyme linked immunosorbent assay (ELISA).

RESULTS

There was no significant difference in genotype and allele frequency of SNP at position -308 (G/A) in the promoter region of the human TNF-alpha gene as well as the SNP at position 252 (A/G) in the human TNF-beta gene between the GDM and control subjects. Using the logistic regression model, it was found that the SNP in the TNF-alpha as well as TNF-beta were not associated with development of GDM. In addition, the TNF-alpha levels in the plasma of GDM and control mothers were not significantly different.

CONCLUSIONS

In the population studied, the SNP in position -308 (G/A) of the human TNF-alpha or in position 252 (A/G) of the human TNF-beta gene is not an independent risk factor or a predictor for GDM.

Association between tumor necrosis factor alpha 308G/A polymorphism and increased proinflammatory cytokine release after cardiac surgery with cardiopulmonary bypass in the Korean population

OBJECTIVES

The G-308A polymorphism of the tumor necrosis factor alpha (TNF-alpha) gene has been suggested to be linked to high TNF promoter activity in in vitro studies. However, there have been some controversies in in vivo studies. This study investigated whether A allele at TNF-308 site is associated with (1) the changes in plasma cytokine levels during and after cardiopulmonary bypass (CPB) and (2) an increased incidence of pulmonary morbidity after CPB.

DESIGN

Prospective and observational investigation.

SETTING

A university hospital, single institution.

PARTICIPANTS

Patients scheduled for cardiac surgery with CPB.

INTERVENTION

TNF genotype was determined by the real-time polymerase chain reaction method. IL-6 and TNF-alpha levels were measured by enzyme-linked immunosorbent assay at the following time points: T1, before initiation of CPB; T2, 30 minutes of CPB; T3, 30 minutes after CPB; T4, 2 hours after CPB; and T5, 24 hours after CPB. The oxygen index, serum creatinine level, 24-hour blood loss, intubation time, and length of intensive care unit (ICU) stay were examined.

MEASUREMENTS AND MAIN RESULTS

The levels of TNF-alpha in group A (TNF-308GA/AA, n = 25) were higher at T3, T4, and T5 than group G (TNF-308GG, n = 225). The levels of IL-6 showed no statistical difference. The oxygenation index, serum creatinine level, 24-hour blood loss, intubation time, and length of ICU stay showed no statistical difference.

CONCLUSIONS

TNF G-308A polymorphism may be associated with excess TNF-alpha secretion in this study and may not be associated with excess IL-6 secretion and postoperative morbidity after CPB.

Association between a polymorphism in the lymphotoxin-a promoter region and migraine

OBJECTIVE

The aim of this study was to determine whether polymorphisms in the lymphotoxin (LTA)-tumor necrosis factor (TNF) region are associated with the risk of migraine.

BACKGROUND

Previous studies concerning the role of TNFalpha in migraine have provided conflicting results. It has been reported that LTA could be a susceptibility gene in migraine. It is possible that the TNFalpha polymorphism associated with migraine is in linkage disequilibrium with other functional polymorphisms that influence migraine risk. Moreover, there are significant differences among the allele frequencies of TNF gene variants among populations from different ethnic groups.

METHODS

In a case-control study, including 439 migraine patients and 382 controls, we examined the association between 15 single nucleotide polymorphisms in the coding and promoter regions of LTA and TNFalpha genes, which are located within the 22 kb around TNF and the risk of migraine. We performed a chromatin immunoprecipitation (ChIP) assay and an electrophoretic mobility shift assay (EMSA) to identify differential protein-DNA binding of LTA-294.

RESULTS

Homozygosity for the LTA-294C allele was significantly associated with an increased risk of migraine compared with CT/TT carriers (corrected P= .005, odds ratio [OR]= 1.7, 95% confidence interval [CI] 1.3-2.3). Haplotype TGAAC was found to be significantly associated with a protective effect against migraine (P= .0005, Bonferroni corrected P= .003, OR = 0.7, 95% CI 0.5-0.8). There was no differential protein-DNA binding pattern in both EMSA and ChIP assays.

CONCLUSIONS

We found that the LTA haplotypes were associated with migraine among Koreans and that the best marker for this is the LTA-294 T/C polymorphism. Our results indicate that these associations should be defined in the context of the involvement of other genetically linked region, such as human leukocyte antigen (HLA) loci.

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.