Polymorphism of tumour necrosis factor-alpha (TNF-alpha) at position -308 in relation to ankylosing spondylitis

Tumour necrosis factor (TNF) gene polymorphism influences TNF-alpha production in lipopolysaccharide (LPS)-stimulated whole blood cell culture in healthy humans

TNF-alpha is involved in infectious and immuno-inflammatory diseases. Different individuals may have different capacities for TNF-alpha production. This might determine a predisposition to develop some complications or phenotypes of these diseases. The aims of our study were to assess the inter-individual variability of TNF-alpha production and to correlate this variability to a single base pair polymorphism located at position -308 in TNF gene. We studied 62 healthy individuals. TNF-alpha production after LPS stimulation was evaluated using a whole blood cell culture model. The TNF gene polymorphism was studied by an allele-specific polymerase chain reaction. Other cytokines produced in the culture, soluble CD14 concentrations and expression of CD14 on blood cells were also measured. Among the 62 individuals, 57 were successfully genotyped. There were 41 TNF1 homozygotes and 16 TNF1/TNF2 heterozygotes. TNF-alpha production after LPS stimulation of whole blood cell culture was higher among TNF2 carriers than among TNFI homozygotes (929pg/ml (480-1473pg/ml) versus 521 pg/ ml (178-1307 pg/ml); P<0.05). This difference was even more significant after correction of TNF-alpha production for CD14 expression on blood cells. In conclusion, the single base pair polymorphism at position -308 in the TNF gene may influence TNF-alpha production in healthy individuals.

Association of different tumor necrosis factor alpha promoter allele frequencies with ankylosing spondylitis in HLA-B27 positive individuals

OBJECTIVE

To investigate the potential association of tumor necrosis factor alpha (TNFalpha) promoter alleles with ankylosing spondylitis.

METHODS

DNA from 141 HLA-B27 positive Caucasian patients with ankylosing spondylitis and 46 B27-positive and 99 B27-negative healthy Caucasian controls was investigated by polymerase chain reaction amplification of the TNFalpha promoter region and subsequent dot-blot analysis with allele-specific oligonucleotides.

RESULTS

There was a significant decrease in the promoter alleles TNF-238.2 and TNF-308.2 in the ankylosing spondylitis group (266 wild-type alleles, 16 variant alleles) compared with the B27-positive (75 wildtype promoter alleles, 17 variant alleles; P<0.0004) and the B27-negative (159 wild-type promoter alleles, 39 variant alleles; P< 0.00001) control groups. Positivity for the variant promoter alleles conferred protection and a relative risk of 0.3 to B27-positive individuals.

CONCLUSION

These data indicate that allelic variations in the TNFalpha promoter influence disease susceptibility in HLA-B27 positive individuals. This protective effect of variant promoter alleles could be related to differences in TNFalpha production or could reflect the association of different B27 haplotypes with ankylosing spondylitis.

Tumor necrosis factor gene polymorphisms in ankylosing spondylitis

Despite the strength of the association of ankylosing spondylitis (AS) with HLA-B27, other genetic elements could play a possible role in the pathophysiology of AS. In view of its gene location, in the proximity of the HLA-B locus, and biological effects, tumor necrosis factor (TNF) genes are potential candidates for additive susceptibility factors to AS. TNFalpha and TNFbeta genotypes were analyzed by PCR-RFLP in 57 patients with AS, 102 random controls and 30 HLA-B*27-positive controls. No significant differences of TNFalpha promoter variations at position -308 and -238 were found in AS patients in comparison with controls. The -244 polymorphism was not detected in our population. The TNFbeta genotype frequency was significantly different between AS patients and random controls. However, when the distribution of the TNFbeta genotype was compared in B*27-positive AS patients and controls, these differences disappeared. In addition, we demonstrated that the TNFbeta*1 was in strong linkage disequilibrium with the B*27 allele, which may explain the differences observed for the TNFbeta genotype among AS patients and random controls. Our data suggest that the polymorphisms of TNFalpha and TNFbeta genes do not have an independent effect on AS susceptibility.

The presence of anti-neutrophil antibodies reflects clinical and genetic heterogeneity within inflammatory bowel disease

A detailed investigation of the relationship between anti-neutrophil cytoplasmic antibodies (ANCA) status, HLA genotype, and clinical patterns of inflammatory bowel disease was carried out, involving 236 European patients resident in the United Kingdom [120 had ulcerative colitis (UC), 116 had Crohn's disease (CD)]. ANCA status was determined on coded plasma samples in Los Angeles using a two-stage assay [fixed neutrophil enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence], and HLA genotyping was carried out by polymerase chain reaction. The results provide evidence that ANCA reflect clinical and genetic heterogeneity within the inflammatory bowel diseases. In the UC patients, 78.3% were ANCA positive [64.2 perinuclear (pANCA)], but only 46.5% CD patients were ANCA positive (19.3% pANCA). Furthermore, mean ELISA binding was significantly lower in CD (14.5% +/- 18.8% versus 40.5% +/- 41.0% in UC, p = 2.31 x 10(-9)). Only 15 CD samples, all from patients with colonic disease, displayed ELISA > 20%; and the six CD patients with highest ELISA binding had clinical features very similar to ulcerative colitis. Moreover, in UC, significant relationships between ANCA status and genotype were noted. Thus, 92.7% of patients with the DR3 DQ2 TNF2 haplotype were ANCA positive [p = 0.03 versus DR3 DQ2 TNF2-negative patients (73.9%)]. ELISA binding was increased in DR3 DQ2 TNF2-positive patients (56.0 versus 35.7%, p = 0.02). In this population of UC, ANCA was not associated with DR2, DR4, or clinical pattern. These data emphasize the many factors that need to be considered in genetic marker studies in inflammatory bowel disease. Extensive disease heterogeneity, ethnicity, and methodological differences in ANCA detection are all pertinent.

Tumor necrosis factor-alpha gene polymorphism in chronic bronchitis

Airway inflammation is an important pathologic feature in chronic bronchitis, and we hypothesized that individuals with greater inflammatory responses may be more likely to acquire the disease. A polymorphism at -308 position of the tumor necrosis factor-alpha (TNF-alpha) gene has been described, with the rarer allele, TNF2, demonstrated to have higher inducibility in vitro. We investigated the distribution of this polymorphism in a case-control study. The genotype was determined in 42 male patients with chronic bronchitis, 42 sex-, age-, and smoking index-matched control subjects, and 99 random-sampled schoolchildren. We report here that the TNF2 allele is overrepresented in the patient group. The allele frequency of TNF2 is 5.1% in the schoolchildren, 2.4% in the control group, and 19% in the bronchitis group (p < 0.01). Carriage of the TNF2 allele confers a higher risk to the development of chronic bronchitis (odds ratio = 11.1, 95% CI = 2.89-42.57). The results demonstrate the important pathologic role of TNF-alpha in chronic bronchitis and suggest that greater inflammatory response may predispose an individual to this disease.

Polymorphism in the tumor necrosis factor-alpha promotor region and in the heat shock protein 70 genes associated with malignant tumors

BACKGROUND

Tumor necrosis factors (TNFs) and heat shock protein 70 (hsp70) are determining factors in immunologic mechanisms to tumor cells. The authors designed a case-controlled study to investigate the potential association of the polymorphisms of TNF-alpha and of hsp70-2 and hsp70-hom genes with malignant tumors.

METHODS

The authors used an allele specific polymerase chain reaction to characterize the variation of the TNF-alpha promotor region in 124 unrelated Tunisian patients with malignant tumors (non-Hodgkin's lymphoma, breast carcinoma, and other tumors) and 106 healthy control subjects. Using polymerase chain reaction and restriction enzyme digestion, polymorphic analysis of hsp70-2 and hsp70-hom genes was performed in patients with non-Hodgkin's lymphoma, in those with breast carcinoma, and in control subjects.

RESULTS

Analysis of TNF-alpha polymorphism in patients with malignant tumors and in control subjects demonstrated a high relative frequency of the TNF2 allele in the cancer patients. The relative risk (RR) of lymphoma was especially high in association with TNF1/TNF2 heterozygotes (RR = 6.7; P < or = 0.0001). Polymorphism analysis of the hsp70-2 and hsp70-hom genes in patients with lymphoma and in those with breast carcinoma revealed that these patients had highly significant differences in the genotypic distribution of these biallelic loci compared with the control subjects. Homozygosity for one hsp70-2 allele was significantly associated with lymphoma (RR = 18.2; P < or = 0.0001) and with breast carcinoma (RR = 16.3; P < or = 0.001).

CONCLUSIONS

Tunisian persons carrying the TNF2 allele may have an increased risk of cancer. In this study, non-Hodgkin's lymphoma and breast carcinoma were significantly associated with polymorphism in hsp70 genes.

Polymerase chain reaction haplotyping using 3' mismatches in the forward and reverse primers: application to the biallelic polymorphisms of tumor necrosis factor and lymphotoxin alpha

A polymerase chain reaction with sequence-specific primers (PCR-SSP) system that operates under identical conditions to HLA phototyping was devised for characterizing polymorphisms in tumor necrosis factor (TNF) and lymphotoxin alpha (LT-alpha). Mismatches at the 3' end were incorporated into the forward and reverse primers of each PCR so as to unequivocally establish the cis/trans status between the biallelic sites. Three previously described biallelic polymorphisms in TNF and three in LT-alpha were characterized in a 24-reaction PCR-SSP system. The method was used to genotype 20 cell lines and 201 HLA class I and II typed controls from the United Kingdom at the TNF and LT-alpha loci. Population frequencies of TNF haplotypes were determined as was linkage disequilibrium with HLA-A, B, Cw, DRB1 and DQB1 loci. In each gene there were 8 theoretical polymorphic combinations; 4 were observed in TNF and 4 in LT-alpha. A total of 11 TNF-LT-alpha haplotypes were determined from apparent homozygous controls and statistical analysis.

Cytokine gene polymorphisms in inflammatory bowel disease

BACKGROUND

Concordance rates in siblings and twins provide strong evidence that genetic susceptibility is important in the pathogenesis of inflammatory bowel disease. The number and identity of susceptibility genes is largely uncertain. Cytokine genes are attractive candidate loci.

AIMS

To study allelic frequencies of polymorphisms of the interleukin-1 receptor antagonist (IL-1RA) gene and the tumour necrosis factor alpha gene in patients with inflammatory bowel disease.

SUBJECTS

One hundred and twenty nine North European caucasoid patients with ulcerative colitis, 120 patients with Crohn's disease, and 89 healthy controls.

METHODS

Genotyping was performed by polymerase chain reaction. A variable number of tandem repeats (VNTR) in the IL-1RA gene and a single base pair polymorphism in the TNF alpha gene promoter region (TNF-308) were analysed.

RESULTS

No significant differences in IL-1RA VNTR allelic frequencies were noted between Crohn's disease (allele 1: 72.6%, allele 2: 24.7%, allele 3: 2.6%), ulcerative colitis (72.6%, 24.3%, 3.1%, respectively), and controls (76.9%, 20.8% and 2.3%). Some 42.4% of patients with ulcerative colitis and 43.4% patients with Crohn's disease were carriers of allele 2, compared with 34.8% healthy subjects. The TNF2 allele was modestly reduced in Crohn's disease (13.2%), compared with healthy subjects (21.3%; p = 0.04), and ulcerative colitis (21.6%).

CONCLUSIONS

The associations demonstrated are modest: these polymorphisms are unlikely to be important determinants of overall disease susceptibility.

Non-HLA-B27 genetic factors in HLA-B27 associated diseases

Family and twin studies showed that besides HLA-B27 other genetic factors are of significance for the pathogenesis of ankylosing spondylitis, reactive arthritis or acute anterior uveitis. There are up to now no strong indications that any subtype of B27 is especially associated with these diseases. Also the indications that B2703 and B2706 are protective should be further substantiated. HLA-B27/HLA-B60 heterozygotes have a three times higher risk to develop ankylosing spondylitis as persons with another B type opposite B27. Haplotype studies made it unlikely that the other genetic factors are situated on chromosome 6p. Studies on 23 other genetic marker systems were all negative in this respect.

Tumor necrosis factor alpha-308 alleles in multiple sclerosis and optic neuritis

Tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is believed to play an important role in multiple sclerosis (MS) pathogenesis. A bi-allelic polymorphism in the TNF-alpha promoter region (TNF alpha-308), has been reported to influence levels of TNF-alpha production. In the present study, we investigated the TNF alpha-308 polymorphism in 93 patients with MS, 17 patients with optic neuritis (ON) and 95 healthy individuals using an allele-specific PCR technique. Allelic genotype was compared with TNF-alpha mRNA expression levels and HLA class II phenotypes. No significant difference regarding the TNF alpha-308 polymorphism was observed between MS patients and controls. Specifically, the less common allele, TNF2, which is associated with higher expression levels of TNF-alpha, was somewhat less frequent among MS patients. In fact, analysis of 19 patients homozygous for the MS associated HLA-DR-DQ haplotype HLA-Dw2 showed that this haplotype does not carry the TNF2 allele. In addition, in 47 patients, the TNF-alpha alleles did not correlate with expression levels measured as numbers of TNF-alpha expressing cells. Thus, we found no evidence for an important role of TNF alpha-308 polymorphism for genetic susceptibility to MS.