Tumour necrosis factor-alpha (TNF-alpha) polymorphisms-857C/A and -863C/A are associated with TNF-alpha secretion from human adipose tissue

Associations between tumor necrosis factor-α gene polymorphisms and the risk of Guillain-Barré syndrome and its subtypes: A systematic review and meta-analysis

This meta-analysis aimed to assess the relationship between tumor necrosis factor-α (TNF-α) polymorphisms and Guillain-Barré syndrome (GBS) or its subtypes of acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and acute motor-sensory axonal neuropathy (AMSAN). A total of six studies with 1013 cases and 1029 controls were included. Our pooled data indicated that TNF-α 308G/A polymorphism was significantly associated with GBS, AMAN, and AMSAN but not with AIDP; TNF-α 857C/T polymorphism was significantly associated with AMAN but not with GBS or AIDP. Besides, no association was found between TNF-α 238G/A and 863C/A polymorphisms and GBS or its subtypes.

Correlation of HLA-DQ and TNF-α gene polymorphisms with ocular myasthenia gravis combined with thyroid-associated ophthalmopathy

The present study aims to explore the correlation of human leucocyte antigen (HLA)-DQ and tumour necrosis factor (TNF)-α gene polymorphisms with ocular myasthenia gravis (OMG) combined with thyroid-associated ophthalmopathy (TAO). From March 2009 to March 2015, 56 OMG patients complicated with TAO (OMG + TAO group), 134 patients diagnosed with OMG only (OMG group) and 236 healthy individuals (control group) were enrolled in the present study. PCR-sequence specific primer (PCR-SSP) was used for HLA-DQ genotyping and PCR-restriction fragment length polymorphism (PCR-RFLP) for TNF-α genotyping. ELISA kit was applied to detect acetylcholine receptor antibody (AchRAb) level and chemiluminescence immunoassay (CLIA) to measure thyroid-associated antibody (T-Ab) level. Logistic regression analysis was carried out to analyse the risk factors for OMG combined with TAO. DQA1*0103 showed lower frequency in the OMG group than in the control group. DQA1*0301 showed increased and DQB1*0601 showed decreased frequency in the OMG + TAO group. DQB1*0501 showed higher frequency in the OMG and OMG + TAO groups than in the control group. Patients carrying TNF-α -863C > A (CA + AA) might confront with greater risks of OMG combined with TAO. Frequency of DQA1*0103/*0301 and DQB1*0501/*0601, and TNF-α -863C > A, -238G > A and -308G > A were associated with the levels of AchRAb and T-Ab. TNF-α -863C > A (CA + AA) and high level of T-Ab were risk factors for OMG combined with TAO. Our results demonstrate that TNF-α -863 polymorphism is possibly correlated with the risk of OMG combined with TAO.

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.

Association of tumor necrosis factor-α gene promoter polymorphisms (-308G/A, -238G/A) with recurrent spontaneous abortion: a meta-analysis

Tumor necrosis factor-α (TNF-α) gene promoter polymorphisms (-308G/A, -238G/A) have been associated with increased recurrent spontaneous abortion (RSA) risk, but the results of published articles are controversial. Hence, a meta-analysis was performed to assess the effect of TNF-α -308G/A, -238G/A polymorphisms on RSA risk. Heterogeneity testing and sensitivity analysis were performed using RevMan 5.0 software. Publication bias was assessed by the funnel plot method and modified Egger's linear regression test. In 12 studies for the TNF-α -308G/A polymorphism, the summary odds ratio (OR) with the corresponding 95% confidence interval (95% CI) was 1.04 (95% CI: 0.86, 1.26) under a fixed-effect model in the overall population. In 5 studies for the TNF-α -238G/A polymorphism, the summary OR with the corresponding 95% CI was 1.11 (95% CI: 0.60, 2.03) under a random-effect model in the overall population. We could not identify the sources of heterogeneity for TNF-α -238G/A. In addition, no evidence of publication bias was detected. The results of this meta-analysis indicate that TNF-α -308G/A, -238G/A polymorphisms are not significantly associated with the risk of RSA in the overall population. However, more convincing evidence is required to draw a solid conclusion on the relation between the TNF-α -238G/A polymorphism and the risk of RSA.

Genetics of adipose tissue biology

Adipose tissue morphology and release of free fatty acids, as well as peptide hormones, are believed to contribute to obesity and related metabolic disorders. These adipose tissue phenotypes are influenced by adiposity, but there is also a strong hereditary impact. Polymorphisms in numerous adipose-expressed genes have been evaluated for association with adipocyte and clinical phenotypes. In our opinion, some results are convincing. Thus ADRB2 and GPR74 genes are associated with adipocyte lipolysis, GPR74 also with BMI; PPARG and SREBP1, which promote adipogenesis and lipid storage, are associated with T2D and possible adiposity; ADIPOQ and ARL15 are associated with circulating levels of adiponectin, ARL15 also with coronary heart disease. We anticipate that the use of complementary approaches such as expression profiling and RNAi screening, and studies of additional levels of gene regulation, that is, miRNA and epigenetics, will be important to unravel the genetics of adipose tissue function.

Association of tumor necrosis factor-alpha gene promoter polymorphisms with acute viral hepatitis in the Indian population

The key elements that determine the host response to either the self-limited or a severe fulminant form of liver disease are unclear. We have investigated the potential association of single nucleotide polymorphisms (SNPs) in the promoter region of tumor necrosis factor-alpha (TNFalpha) in their susceptibility to acute viral hepatitis (AVH) and fulminant hepatic failure (FHF) patients exhibiting specific viral etiology. A total of 124 individuals including 64 cases comprising 27 FHF, 37 AVH, and 60 healthy controls were recruited. SNPs at -238 (G/A), -308 (G/A), -857 (C/T), and -863 (C/A) of TNFalpha were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and confirmed by direct sequencing. Serum levels of TNFalpha were determined at admission and death or recovery. Association between the TNFalpha genotype and susceptibility to FHF was not evident; however, carrier genotypes in relation to the -308 (GA/AA) and -857 (CT/TT) loci were found to be significantly (P < or = 0.05) associated with susceptibility to AVH in relation to controls. The mean TNFalpha serum levels at admission were significantly higher (P < 0.001) in FHF than AVH patients, but no marked difference was observed between FHF-E (expired; n = 17) and FHF-S (survivors; n = 10), though the former were comparatively higher. This study suggests that SNPs at -308 and -857 of the TNFalpha promoter may represent an increased risk for the development of AVH but not for FHF in the Indian population.

Tumor necrosis factor-alpha polymorphisms in women with idiopathic recurrent miscarriage

We investigated the association of tumor necrosis factor-alpha (TNFalpha) gene polymorphisms with idiopathic recurrent miscarriage (RM). TNFalpha -1031T/C, -863C/A, -857C/T, -376G/A, -308G/A, -238G/A, and +488G/A single nucleotide polymorphisms (SNPs) were investigated in 204 RM women and 248 age-matched parous women by PCR-restriction fragment length polymorphism. Significantly higher frequencies of -1031C and -376A alleles were seen in RM patients; significant differences were also noted in the distribution of -1031T/C, -376G/A, and -238G/A genotypes between case and control subjects. Haploview analysis revealed high linkage disequilibrium between -857C/T and +488G/A SNPs, but was lower between the other polymorphisms. Of the possible 52 seven-locus haplotypes constructed, 10 were common, and were included in subsequent analysis. Increased frequency of CCCGGGG and CCCGGAA haplotypes, and reduced frequency of TCCGGGG and TCCGGGA haplotypes were seen in RM patients than in controls. When the Bonferroni correction was applied, differences were significant for the CCCGGAA haplotype, which was higher (OR=4.14; 95% CI=1.84-8.95), and the TCCGGGA haplotype, which were lower among RM cases (OR=0.09; 95% CI=0.02-0.68), thereby conferring RM susceptibility and protection to these haplotypes, respectively. Multivariate analysis confirmed the positive association of only CCCGGAA haplotype with RM (P=0.010; aOR=2.03; 95% CI=1.18-4.47), after controlling for a number of covariates. These results demonstrate that the TNFalpha polymorphisms, in particular the -1031T/C variant, are significantly associated with idiopathic RM. Additional replication studies on other racial groups are needed to confirm our findings.

Genetic predispositions to low-grade inflammation and type 2 diabetes

Insulin resistance and cardiovascular disease share common pathophysiological mechanisms, as the chronic activation of the innate immune system. This system constitutes the first line of body's defense and is constituted by different barriers (e.g., epithelia, adipose tissue) and different blood and tissue components (e.g., macrophages, neutrophils). This system generates the acute-phase response in which different acute-phase proteins and cytokines are produced in response to different aggressions as infections and traumatisms. The aim of this response is to eradicate these agents, to repair the harmed tissues, and, through increased insulin resistance, to optimize the energetic substrates, which will be drained to vital tissues and organs (i.e., brain and the immune system). Evolutionary pressures have led to survival of the fittest individuals, those with the genetics that allows the best defense against infection and periods of famine. Evidence is reported according to which gene polymorphisms in the molecules regulating the inflammatory cascade are associated with body composition, insulin action, and characteristics of the metabolic syndrome. The evolutive advantages of increased inflammatory responses, hypersecretion of proinflammatory cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, and IL-18], or decreased anti-inflammatory molecules (adiponectin, certain TNF-alpha isoforms, soluble CD14, etc.), would lead in westernized countries to chronic inflammation conditions, such as obesity and type 2 diabetes, resulting in cardiovascular disease.

Adiposity signals, genetic and body weight regulation in humans

Numerous signals convey information about body fat status from the periphery to the brain areas that control energy homeostasis so that, throughout life, body weight remains nearly stable. These signals mainly originate, either from the adipose tissue, like leptin and to a lesser extent interleukin 6, or from the pancreas, like insulin and amylin. These factors circulate in proportion to body fat mass and they are referred to as "adiposity signals". It is well established, at least for leptin and insulin, that they enter the brain from the plasma where they induce/repress a network of important neuropeptide regulators of energy intake and expenditure. Beside these endocrine signals, a growing amount of literature show data relative to adipocyte-derived molecules, most of them belonging to the cytokine family, like IL6, TNFalpha, IL8, IL10 whose secretion also correlates with body fat mass and that may locally regulate fat mass expansion. Others, like adiponectin, are negatively correlated with body fat mass. These "adiposity molecules" have already been involved in insulin resistance associated with obesity and inflammatory process. They may participate to a complex inter organ dialogue. In this review, we will synthesize data relative to the role played by insulin, leptin and amylin, either alone or through a cross talk, in "energy level sensing" at the brain level. Furthermore, we will develop how "adiposity molecules" through their paracrin and/or autocrin action may contribute to maintain fat mass expansion, therefore representing new adiposity molecules per se. Lastly, since any distortion in the metabolic circuitry of energy homeostasis is susceptible to lead to a pathological status like obesity, the impact of known genetic polymorphisms in genes encoding the adiposity signals will be discussed.

Lower rate of tumor necrosis factor-alpha -863A allele and higher concentration of tumor necrosis factor-alpha receptor 2 in first-degree relatives of subjects with type 2 diabetes

Allelic variants of the tumor necrosis factor-alpha (TNF-alpha) gene seem to contribute to insulin resistance increasing the transcription rate of TNF-alpha. The TNF-alpha -863A allele is associated with a lower expression of TNF-alpha gene and less secretion of the cytokine. To investigate whether an abnormal TNF-alpha system regulation may contribute to early impairment of insulin action in first-degree relatives of patients with type 2 diabetes mellitus (DM), we studied the TNF-alpha -863C/A polymorphism and the soluble fraction of TNF-alpha receptor-2 (sTNFR2) concentration in these subjects in comparison to a control group. A total of 52% of subjects in the relatives' group showed an abnormal oral glucose tolerance (either as impaired glucose tolerance [IGT] or diabetes) and had more features of the insulin resistance syndrome, despite showing similar body composition as controls. The plasma concentration of the sTNFR2 was higher and insulin sensitivity (%S) was lower in the relatives' group than in the controls. Likewise, the TNF-alpha -863A allele was more commonly detected in the control group (10 of 41) than in the relative's group (2 of 36, P =.029). In a multivariate linear regression analysis, neither TNF-alpha -863A allele nor sTNFR2 independently determined %S. Only body mass index (BMI) and the presence of a positive family history of DM were independent determinants of insulin resistance. In summary, our study showed a lower rate of TNF-alpha -863A allele and higher concentrations of sTNFR2 in first-degree relatives of DM subjects. These findings could be included among the genetic, metabolic, and clinical heterogeneity that characterizes the pathophysiology of DM. The presence of abnormalities in the TNF-alpha pathway could predispose to the development of DM in subjects at risk for the disease.

Insulin resistance and chronic cardiovascular inflammatory syndrome

Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Hyperinsulinemia and insulin action were initially proposed as the common preceding factors of hypertension, low high-density lipoprotein cholesterol, hypertriglyceridemia, abdominal obesity, and altered glucose tolerance, linking all these abnormalities to the development of coronary heart disease. The similarities of insulin resistance with another inflammatory state, atherosclerosis, have been described only in the last few decades. Atherosclerosis and insulin resistance share similar pathophysiological mechanisms, mainly due to the actions of the two major proinflammatory cytokines, TNF-alpha and IL-6. Genetic predisposition to increased transcription rates of these cytokines is associated with metabolic derangement and simultaneously with coronary heart disease. Dysregulation of the inflammatory axis predicts the development of insulin resistance and type 2 diabetes mellitus. The knowledge of how interactions between metabolic and inflammatory pathways occur will be useful in future therapeutic strategies. The effective administration of antiinflammatory agents in the treatment of insulin resistance and atherosclerosis is only the beginning of a promising approach in the management of these syndromes.

The human obesity gene map: the 2001 update

This report constitutes the eighth update of the human obesity gene map, incorporating published results up to the end of October 2001. Evidence from the rodent and human obesity cases caused by single-gene mutations, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) uncovered in human genome-wide scans and in crossbreeding experiments in various animal models, association and linkage studies with candidate genes and other markers is reviewed. The human cases of obesity related in some way to single-gene mutations in six different genes are incorporated. Twenty-five Mendelian disorders exhibiting obesity as one of their clinical manifestations have now been mapped. The number of different QTLs reported from animal models currently reaches 165. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 174 studies reporting positive associations with 58 candidate genes. Finally, 59 loci have been linked to obesity indicators in genomic scans and other linkage study designs. The obesity gene map depicted in Figure 1 reveals that putative loci affecting obesity-related phenotypes can be found on all chromosomes except chromosome Y. A total of 54 new loci have been added to the map in the past 12 months, and the number of genes, markers, and chromosomal regions that have been associated or linked with human obesity phenotypes is now above 250. Likewise, the number of negative studies, which are only partially reviewed here, is also on the rise.