Tumor Necrosis Factor Variants Research Articles

Common Variations in the Genes Encoding C-Reactive Protein, Tumor Necrosis Factor-α, and Interleukin-6, and the Risk of Clinical Diabetes in the Women's Health Initiative Observational Study

BACKGROUND Circulating concentrations of high-sensitivity C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) have been associated with an increased risk of diabetes. METHODS To examine the roles of genetic variation in the genes encoding CRP, TNF- α, and IL-6 in the development of diabetes, we conducted a prospective case–control study nested within the Women's Health Initiative Observational Study. We followed 82 069 postmenopausal women (50–79 years of age) with no history of diabetes for incident diabetes for a mean follow-up of 5.5 years. We identified 1584 cases and matched them with 2198 controls with respect to age, ethnicity, clinical center, time of blood draw, and length of follow-up. We genotyped 13 haplotype-tagging single-nucleotide polymorphisms (tSNPs) across 2.3 kb of the CRP (C-reactive protein, pentraxin-related) gene, 16 tSNPs across 2.8 kb of the TNF (tumor necrosis factor) gene, and 14 tSNPs across 4.8 kb of the IL6 [interleukin 6 (interferon, beta 2)] gene. Plasma concentrations of TNF-α receptor 2 (TNF-α-R2) and IL-6 were measured. RESULTS After adjusting for matching factors, confounding variables, and multiple comparisons, we found 8 variants in the TNF gene to be associated with plasma TNF-α-R2 concentrations in white women (q < 0.05). After adjusting for multiple comparisons (q > 0.05), we found no association of any IL6 gene variant with plasma IL-6 concentration, nor did we find any significant associations between any SNPs among these 3 genes and diabetes risk (q > 0.05). CONCLUSIONS We found modest associations between TNF variants and circulating concentrations of TNF-α-R2. Common variants of the CRP, TNF, and IL6 genes were not significantly associated with risk of clinical diabetes in postmenopausal women.

Novel mutants of human tumor necrosis factor with dominant-negative properties

Tumor necrosis factor (TNF) is a polyfunctional cytokine, one of the key mediators of inflammation and innate immunity. On the other hand, systemic or local TNF overexpression is typical of such pathological states as rheumatoid arthritis, psoriasis, Crohn's disease, septic shock, and multiple sclerosis. Neutralization of TNF activity has a marked curative effect for some diseases; therefore, the search for various TNF blockers is a promising field of protein engineering and biotechnology. According to the previously developed concept concerning the possibility of designing dominant-negative mutants, the following TNF variants have been studied: TNFY87H + A145R, TNFY87H + A96S + A145R, and TNFV91N + A145R. All of these form inactive TNF heterotrimers with the native protein. The ability of mutants to neutralize the effect of TNF was investigated. The addition of mutants to the native protein was shown to provide a concentration-dependent suppression of TNF cytotoxicity against the mouse fibroblast cell line L929. Thus, novel inhibitors of human TNF can be engineered on the basis of these muteins.

Improving TNF as a cancer therapeutic: Tailor‐made TNF fusion proteins with conserved antitumor activity and reduced systemic side effects

Tumor necrosis factor (TNF) is highly pleiotropic cytokine regulating diverse cellular processes such as proliferation, cell migration, angiogenesis, differentiation, apoptosis, necrosis, but also survival. Because of its name-giving tumor necrosis-inducing capabilities, TNF has attracted attention very early for antitumor therapy. Although TNF is in clinical use for treatment of soft tissue sarcoma in isolated limb perfusion, its broad use in tumor therapy is prevented so far by its strong systemic proinflammatory effects. Nevertheless, over the past decade, a variety of tailor-made TNF variants have been developed with the aim to reduce TNFs systemic activity without losing its antitumoral effects. Here, we review the progress made toward improving the efficacy of TNF by genetic engineering, tumor targeting, and introduction of prodrug concepts.

Interactions between Glutathione S- Transferase P1, Tumor Necrosis Factor, and Traffic-Related Air Pollution for Development of Childhood Allergic Disease

BackgroundAir pollutants may induce airway inflammation and sensitization due to generation of reactive oxygen species. The genetic background to these mechanisms could be important effect modifiers.ObjectiveOur goal was to assess interactions between exposure to air pollution and single nucleotide polymorphisms (SNPs) in the β2-adrenergic receptor (ADRB2), glutathione S-transferase P1 (GSTP1), and tumor necrosis factor (TNF) genes for development of childhood allergic disease.MethodsIn a birth cohort originally of 4,089 children, we assessed air pollution from local traffic using nitrogen oxides (traffic NOx) as an indicator based on emission databases and dispersion modeling and estimated individual exposure through geocoding of home addresses. We measured peak expiratory flow rates and specific IgE for inhalant and food allergens at 4 years of age, and selected children with asthma symptoms up to 4 years of age (n = 542) and controls (n = 542) for genotyping.ResultsInteraction effects on allergic sensitization were indicated between several GSTP1 SNPs and traffic NOx exposure during the first year of life (pnominal < 0.001–0.06). Children with Ile105Val/Val105Val genotypes were at increased risk of sensitization to any allergen when exposed to elevated levels of traffic NOx (for a difference between the 5th and 95th percentile of exposure: odds ratio = 2.4; 95% confidence interval, 1.0–5.3). In children with TNF-308 GA/AA genotypes, the GSTP1–NOx interaction effect was even more pronounced. We observed no conclusive interaction effects for ADRB2.ConclusionThe effect of air pollution from traffic on childhood allergy appears to be modified by GSTP1 and TNF variants, supporting a role of genes controlling the antioxidative system and inflammatory response in allergy.

TNF polymorphisms and prostate cancer risk

Inflammation has been hypothesized to increase prostate cancer risk. Tumor necrosis factor (TNF) is an important mediator of the inflammatory process, but the relationship between TNF variants and prostate cancer remains unclear. We examined associations between six TNF single nucleotide polymorphisms (SNPs) (rs1799964, rs1800630, rs1799724, rs1800629, rs361525, rs1800610) and prostate cancer risk among 2,321 cases and 2,560 controls from two nested case-control studies within the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO, n = 2,561, 5 SNPs) and the Cancer Prevention Study II Nutrition Cohort (Nutrition Cohort, n = 2,320, 6 SNPs). Odds ratios and 95% confidence intervals were estimated for individual SNPs and haplotypes in each cohort separately and in pooled analyses. No TNF SNP was associated with prostate cancer risk in PLCO (P-trend > or = 0.16), while in the Nutrition Cohort, associations were significant for 2 highly correlated variants (rs1799724, 1800610, r2 = 0.95; P-trend = 0.04 and 0.02, respectively). In pooled analyses, no single SNP was associated with prostate cancer risk (P-trend > or = 0.08). After adjustment for multiple testing, no SNP was associated with prostate cancer risk in either cohort individually or in the pooled analysis (P-trend all > or = 0.10). Haplotypes based on 5 TNF SNPs did not vary by case/control status in PLCO, but showed marginal associations in the Nutrition Cohort (global P = 0.06) and the pooled analysis (global P = 0.05). Despite somewhat suggestive haplotype results, overall our study does not support an association between TNF variants and prostate cancer risk.

Clinical and genetic risk factors for pneumonia in systemic lupus erythematosus

To define the contribution of polymorphisms in genes encoding tumor necrosis factor (TNF), mannose-binding lectin (MBL), and Fcgamma receptor IIa (FCGR2A) as well as clinical factors, to the development of pneumonia in patients with systemic lupus erythematosus (SLE). We studied 282 SLE patients from a multiethnic cohort. Pneumonia events and clinical risk factors for pneumonia were identified through medical record review. Genotyping was performed for MBL (+223, +230, and +239), TNF (-308, -238, and +488), and FCGR2A (-131H/R) polymorphisms. Univariate analyses were performed to identify clinical and genetic risk factors for pneumonia. Covariates for multivariate analysis included sex, ethnicity, treatment with immunomodulators, and leukopenia. Forty-two patients (15%) had at least 1 episode of pneumonia. Polymorphism of the TNF gene, particularly the -238A allele and a related haplotype, revealed the most striking and consistent association with pneumonia in univariate analyses. Results of multivariate analyses indicated an odds ratio (OR) for the TNF -238A allele of 3.5 (P = 0.007) and an OR for the related haplotype of 5.4 (P = 0.001). Male sex, treatment with immunomodulators, and leukopenia also influenced the risk of pneumonia. These findings suggest that specific TNF variants may identify SLE patients who are at particularly high risk of developing pneumonia. Given the prevalence and excessive morbidity associated with pneumonia in SLE, these findings have clinical relevance and provide insight into the pathogenesis.

Extended TNF Genotyping Identifies TNF -857T as a Risk Factor for Acute Graft-Versus-Host Disease Following Allogeneic Hematopoietic Stem Cell Transplantation.

Extensive evidence supports a role for non-HLA immunogenetic polymorphisms in determining risk and severity of acute GVHD following allogeneic hematopoietic stem cell transplantation (HCT). Tumor necrosis factor (TNF) polymorphisms have been frequently associated with GVHD risk. However, TNF is highly polymorphic and the TNF polymorphism(s) most strongly associated with GVHD remain to be determined. We previously studied three TNF single nucleotide polymorphisms (SNPs; −308, −238 and 488) in a retrospective study of 160 myeloablative HLA-matched related allo-HCTs and found a highly significant association between the intronic TNF 488A allele and risk and severity of acute GVHD and early mortality (Transplantation 2004;27:587). It was unclear if this association was primarily with TNF 488A or secondary to other functionally important TNF alleles in linkage disequilibrium. To clarify the importance of TNF variants in GVHD, we performed extended genotyping of TNF promoter SNPs in the previously described cohort, and in a prospective cohort of myeloablative (n=78) and non-myeloablative (n=56) sibling HLA-matched allo-HCT. Six TNF polymorphisms (−1030, −863, −857, −308, −238, 488) were genotyped in donors and recipients by PCR-SSP. TNF −308/−238/488 haplotypes were directly amplified by PCR, and full TNF haplotypes inferred using Haploview. The incidence of acute GVHD was 53% and 45.8% for myeloablative and non-myeloablative transplants, respectively. Nine TNF haplotypes were identified, and the TNF 488A allele was in strong, but not complete linkage disequilibrium with TNF −857T. TNF −857T was more strongly associated with acute GVHD (OR 11.1) and grade II–IV GVHD (OR 12.3) than 488A (acute GVHD OR 8.6 and grade II–IV GVHD OR 8.9) in the first cohort. These alleles were also associated with acute GVHD in the second cohort, but only in recipients receiving myeloablative conditioning (all acute GVHD, TNF 488A OR 2.9, −857T OR 3.4). Non-significant trends were observed with grade II–IV GVHD, possibly reflecting the reduced frequency of this complication in the later cohort (29% v. 48%). No association or trends were seen in non-myeloablative transplants. Moreover, no associations were identified with the extensively studied −308 or −238 SNPs in either cohort. Together, these data confirm the association between TNF polymorphisms and GVHD in myeloablative transplants, and suggest that −857T, which lies in closer proximity to TNF regulatory regions than 488A, may be the most useful marker for risk prediction. Our results also suggest that the immunogenetic determinants of GVHD vary according to the intensity of conditioning. Further work examining non-myeloablative transplants is required.

Linkage Disequilibrium With Predisposing DR3 Haplotypes Accounts for Apparent Effects of Tumor Necrosis Factor and Lymphotoxin-α Polymorphisms on Type 1 Diabetes Susceptibility

Tumor necrosis factor (TNF) and lymphotoxin alpha (LT-α) are immunomodulators that have been hypothesized to contribute to susceptibility to type 1 diabetes (T1D). Several polymorphisms in the TNF and LT-α loci have been extensively studied for T1D association, with conflicting reports. In this study, we examined two TNF variants and one LT-α variant for T1D association in 283 Caucasian, multiplex T1D families for which complete human leukocyte antigen (HLA) genotyping data are available. Initially, association with T1D was seen for LT-α A1069G (intron A, p = 0.011, rs909253) and TNF G(−308)A ( p < 1 × 10 −5, rs1800629), but no association was observed for TNF G(−238)A (rs361525). After adjusting the data for linkage disequilibrium (LD) with DRB1-DQB1 haplotypes, however, only one polymorphism, TNF G(−238)A showed significant association with T1D ( p < 0.006). When HLA-DR3 haplotypes were examined, the A allele of TNF G(−238)A was significantly overtransmitted to affected offspring ( p < 0.009). Including HLA-B data in the analysis revealed that TNF (−238)A is present exclusively on DR3 haplotypes that also carry HLA-B18. Transmission proportion of B18-DR3 haplotypes did not differ between those with TNF (−238)A and those with TNF (−238)G. Thus, variation at TNF does not affect the T1D risk for B18-DR3 haplotypes, and the apparent association of TNF(−238)A with T1D may simply reflect its presence on a high-risk haplotype.

TNF as a malaria candidate gene: polymorphism-screening and family-based association analysis of mild malaria attack and parasitemia in Burkina Faso

We have previously obtained strong evidence for linkage of mild malaria attack to the MHC region, with a peak close to the tumor necrosis factor (TNF) gene. We screened, for polymorphisms, the entire TNF gene in the same sample of 34 families comprising 197 individuals living in a Plasmodium falciparum endemic area and we found 17 polymorphisms. In a longitudinal study, we investigated whether the 11 most frequent and informative polymorphisms were associated with mild malaria attack and maximum parasitemia, which was the highest parasitemia in each individual over 2 years. Mild malaria attack and maximum parasitemia were positively correlated. Transmission disequilibrium tests showed nominal evidence for association between TNF-1031, TNF-308, TNF851 and TNF1304 polymorphisms, and mild malaria attack on the one hand, and between TNF-238, TNF851 and TNF1304 polymorphisms, and maximum parasitemia on the other hand. After accounting for multiple tests, we confirmed the association of TNF-238 with maximum parasitemia and the association of TNF1304 and TNF851 with maximum parasitemia and mild malaria attack. The association tests with mild malaria attack suggest a moderate effect of TNF-308 polymorphism. In conclusion, our study suggests that several TNF variants may be part of the genetic determinants for maximum parasitemia and/or mild malaria attack.

Bypassing Inflammatory Signaling

Tumor necrosis factor (TNF) binds to TNF receptors and stimulates inflammatory responses. In patients, an elevated level of TNF is associated with diseases such as rheumatoid arthritis, and inhibition of TNF signaling can be used to treat these diseases. Steed et al. describe an approach that prevents TNF signaling. They used structure-based protein design to engineer dominant-negative TNFs that form heterotrimers with native TNF and in turn prevent binding to TNF receptors. Experiments in animal models show that this approach has promise in attenuating TNF-mediated pathology in vivo. P. M. Steed, M. G. Tansey, J. Zalevsky, E. A. Zhukovsky, J. R. Desjarlais, D. E. Szymkowski, C. Abbott, D. Carmichael, C. Chan, L. Cherry, P. Cheung, A. J. Chirino, H. H. Chung, S. K. Doberstein, A. Eivazi, A. V. Filikov, S. X. Gao, R. S. Hubert, M. Hwang, L. Hyun, S. Kashi, A. Kim, E. Kim, J. Kung, S. P. Martinez, U. S. Muchhal, D.-H. T. Nguyen, C. O'Brien, D. O'Keefe, K. Singer, O. Vafa, J. Vielmetter, S. C. Yoder, B. I. Dahiyat, Inactivation of TNF signaling by rationally designed dominant-negative TNF variants. Science 301 , 1895-1898 (2003). [Abstract] [Full Text]

Inactivation of TNF signaling by rationally designed dominant-negative TNF variants.

Tumor necrosis factor (TNF) is a key regulator of inflammatory responses and has been implicated in many pathological conditions. We used structure-based design to engineer variant TNF proteins that rapidly form heterotrimers with native TNF to give complexes that neither bind to nor stimulate signaling through TNF receptors. Thus, TNF is inactivated by sequestration. Dominant-negative TNFs represent a possible approach to anti-inflammatory biotherapeutics, and experiments in animal models show that the strategy can attenuate TNF-mediated pathology. Similar rational design could be used to engineer inhibitors of additional TNF superfamily cytokines as well as other multimeric ligands.