TNF Alleles Research Articles

HLA-DQ2-Negative Celiac Disease in Finland and Spain

Genetic susceptibility to celiac disease (CD) is strongly associated with DQA1∗0501 and DQB1∗02 (= DQ2). To study whether CD patients without DQ2 share other MHC class II or TNF alleles, we screened DQ2-negative patients in Finland and Spain. Twelve of 84 (14%) Finnish patients and 13 of 189 (6%) Spanish patients were negative for DQ2. We observed that all but two of altogether 25 DQ2-negative patients had the DR4 DQ8 haplotype, or either DQA1∗0501 or DQB1∗02 alone. Also, all but three were positive for DRB4∗01. The only patients without any of these alleles were both positive for DR13. There was a clear difference between Finland and Spain: Ten (83%) of the 12 Finnish DQ2-negative patients but only five (38%) of the 13 Spanish patients had DRB1∗04, DQA1∗03, DQB1∗0302 (= DQ8) alleles. Of the Spanish patients, eight (62%) had DQB1∗02 without DQA1∗0501 and three (23%) had DQA1∗0501 without DQB1∗02. None of the TNF, TAP, or DPB1 alleles was found to be significantly associated with CD. Our results indicate that in addition to the DQ2 heterodimer, the other major risk alleles for CD are DR4 DQ8, and either DQA1∗0501 or DQB1∗02 alone. Patients without these alleles appear to be very rare, only two (0.7%) were identified in altogether 253 patients tested.

The −308 tumor necrosis factor-α promoter polymorphism effects transcription

Since the tumor necrosis factor alpha (TNF-α) gene was found to be located in the central major histocompatibility complex (MHC) there has been much speculation concerning a genetic association between particular TNF alleles and disease susceptibility. A relationship between the MHC haplotype Al, B8, DR3, TNF-α expression levels and susceptibility to autoimmune disease has been suggested by several groups. The identification of the −308 polymorphism and its association with the HLA Al, B8, DR3 haplotype have led to speculation that the polymorphism may play a role in the altered expression of TNF-α. We have demonstrated that the region (−323 to −285) encompassing −308 in the TNF2 allele binds nuclear factors differently to the same region in the promoter of the more common TNF1 allele. The G A −308 polymorphism affected the affinity of factor binding and resulted in a factor binding to TNF2 but not TNF1. The observed differential binding was shown to be functional, with the 38 by region from TNF2 causing a two-fold greater activity of a heterologous promoter over that due to the same region in TNFI. To further substantiate the functional consequences of the TNF-α −308 polymorphism, we analysed both allelic forms of the TNF-α promoter region (−993 to +110) in a transient transfection assay, using luciferase as a reporter gene. The results showed that when present with the 3′UTR the −308A allelic form gave a two-fold greater level of transcription than the −308G form in PMA-stimulated Jurkat and U937 cells. This suggests that the −308 G A polymorphism may play a role in the altered TNF-α gene expression observed in individuals with the HLA Al, B8, DR3 haplotype.

Tumor necrosis factor α-308 gene variants in relation to major histocompatibility complex alleles and Felty's syndrome

The location of the human TNF genes within the MHC complex has prompted much speculation about the role of TNF alleles in the etiology of MHC-associated autoimmune diseases. On sequencing the 5′ regulatory region of the human TNFA gene a G ( TNFA −308G) to A ( TNFA −308A) transition polymorphism at position −308 was discovered. We have developed a simple PCR assay to facilitate the screening of the −308 polymorphism at the DNA level. In view of the possible linkage between the TNFA −308A allele and a certain MHC type, TNFA−308 genotypes in HLA-typed healthy individuals ( n = 88) were determined. A statistically significant association between the TNFA −308A allele and HLA-DR3, DQB1 ∗0201, DQA1 ∗0501, A1, B8, and the Ncol 5.5-kb RFLP of the TNFB gene was observed. In addition, we determined the frequency of the TNFA −308A allele in patients with FS ( n = 13), an HLA-DR4-associated disease. In this study, no association was found of Felty's syndrome with the TNFA −308A allele, indicating that this allele does not appear to be a susceptibility factor for FS. Human Immunology 41, 259–266 (1994).

Polymorphism of the tumor necrosis factor genes in patients with dermatitis herpetiformis.

In 18 patients with dermatitis herpetiformis (DH) of whom 16 were HLA-DR3 positive and 14 had the HLA-B8, -DR3 haplotype, the frequencies of known mutations of the tumor necrosis factor alpha (TNF-alpha) and TNF-beta genes were investigated using restriction fragment length polymorphism analysis and the single-strand conformational polymorphism technique. In DH, the phenotype frequency (28%) and allele frequency (0.58) of the rare TNF-beta allele TNFB*1 were significantly increased (normal control 12.4% and 0.37). For the TNF-alpha promoter/enhancer polymorphism, the rare allele TNF2 was more frequent in DH patients (11%, 0.47) compared to controls (2%, 0.16). Since functional studies have associated the rare TNFB*1 and TNF2 alleles with a higher secretion of TNF upon activation in vitro, the predominance of these two 'high-response' TNF alleles in DH patients may represent a genetic basis for the chronic inflammatory response in the skin and mucosal tissues of patients with DH.

Definition of microsatellite size variants for Tnfa and Hsp70 in autoimmune and nonautoimmune mouse strains.

We have cloned and sequenced the upstream regulatory region of tumor necrosis factor alpha (Tnfa) gene in 12 different mouse strains and identified an allelic polymorphism in the upstream regulatory region of the mouse Tnfa gene. The TNF allele found in the NZW strain is distinct from those of all other H-2 haplotypes, supporting our previous suggestion that this allele may be associated with a regulatory or structural defect. In addition, simple tandem repeat sequences (microsatellites) within the promoter region of the Tnfa gene and the 3' untranslated region of one of the members of the HSP70 family (Hsp68c clone) were utilized as genetic markers. Ten TNF size variants and twelve HSP70 variants were identified in over forty mouse strains. Using these markers in a set of congenic mice, we mapped this member of the HSP70 family to the central portion of the H-2 complex, centromeric to the Tnfa gene. The NOD and NZW strains carry unique HSP70 alleles based on the variability in the length of this marker. These findings raise the possibility that this protein may play a role in the association of the major histocompatibility complex with these autoimmune diseases.

Allelic Variation in the TNF‐β Gene Does Not Explain the Low TNF‐β Response in Patients With Primary Biliary Cirrhosis

Autoimmune disorders in humans are often associated with particular alleles of major histocompatibility genes. However, the chronic inflammatory liver disease primary biliary cirrhosis (PBC) has not been found to be correlated with certain haplotypes so far. Interestingly, an impaired production of tumour necrosis factor beta (TNF-beta) upon mitogen stimulation was observed for PBC patients, especially in the immunologically active stages of the disease. Furthermore, the identification of alleles of the TNF-beta gene which differ in one unique amino acid, and in the production of TNF-beta after phytohaemagglutinin stimulation, has prompted the idea of a possible linkage between the impaired TNF-beta response in PBC and the genetic prevalence of a certain TNF haplotype. We report here a rapid method for typing the TNFB*1 and TNFB*2 genes by a standard polymerase chain reaction. PBC patients (n = 60) as well as randomized healthy controls (n = 179) of the Munich area were studied for the occurrence of the TNF alleles. No deviation was found in the PBC collective (0.7) for the TNFB*2 distribution when compared with the control (0.67).

A polymorphic microsatellite in the tumor necrosis factor alpha promoter identifies an allele unique to the NZW mouse strain.

We have amplified a (CA)n:(GT)n microsatellite from the TNF promoters of a panel of mouse strains using the polymerase chain reaction. The length of the microsatellites was polymorphic, with eight alleles observed among 15 inbred strains bearing seven distinct H-2 haplotypes, and four outbred strains. In B10 congenic strains, the TNF allele detected by microsatellite polymorphism segregated with the MHC, and in recombinant haplotypes (NOD, NZW), it segregated with H-2D. The TNF allele found in the NZW strain (H-2z) was distinct from those of all other haplotypes, consistent with the hypothesis that this strain may carry a genetic defect in TNF production.