A Tumour Necrosis Factor Beta Gene Polymorphism in Relation to Monokine Secretion and Insulin‐Dependent Diabetes Mellitus

Abstract

HLA-class III region genes may be associated with susceptibility to insulin-dependent diabetes mellitus (IDDM). In this study an NcoI polymorphism of the tumour necrosis factor beta (TNF-beta) gene, which is positioned next to the tumour necrosis factor alpha (TNF-alpha) gene in the HLA class III region, was detected by restriction fragment length polymorphism (RFLP). This polymorphism has previously been reported to be located in the TNF-alpha gene. Caucasian HLA-DR3,4 heterozygous IDDM patients (n = 26) and DR-matched healthy controls (n = 19), as well as randomly selected IDDM patients (n = 27) and controls (n = 25) were studied. In addition four multiplex families (49 individuals) and eight HLA-non-identical sibpairs concordant for IDDM were analysed. The TNF-beta gene RFLP analysis showed fragments of 5.5 kb and 10.5 kb, which behaved as alleles. In all groups there was a haplotype assignment of the TNF-beta 5.5-kb allele to B8,DR3 haplotypes, and of the TNF-beta 10.5-kb allele to B15,DR4-positive haplotypes. The allelic and genotypic frequencies differed between DR3,4 IDDM patients and DR3,4 controls, and the DR3,4 control group differed significantly from the randomly selected control group (P less than 0.0079). In HLA-DR3,4- and DQw8-positive persons, the DR3 haplotypes carried the 10.5-kb allele three times more frequently in IDDM patients than in controls, suggesting that the 10.5-kb allele when present on DR3 haplotypes may contribute to susceptibility to IDDM in DR3,4 heterozygous individuals. A contributory role of the 10.5-kb allele in genetic IDDM susceptibility was supported by the sibpair analysis, in which all were TNF-beta identical. Five were 10.5 kb homozygous, and the remaining three pairs were 5.5/10.5 kb heterozygous. Twenty-five healthy and eight newly diagnosed IDDM patients were randomly selected to study the Escherichia coli lipopolysaccharides (LPS)-purified protein derivate (tuberculin) (PPD)-, and phytohaemagglutinin (PHA)-stimulated monocyte (Mo) secretions of interleukin 1 beta (IL-1 beta) and TNF-alpha in relation to the NcoI TNF-beta gene polymorphism. The LPS- and PHA-stimulated Mo IL-1 beta and TNF-alpha secretions were significantly lower for the TNF-beta 5.5/10.5 kb heterozygous individuals than for TNF-beta 10.5 kb homozygous individuals. Furthermore, the Mo IL-1 beta and TNF-alpha secretions of IDDM patients were significantly higher than the Mo secretions of TNF-beta genotype-matched healthy controls. This study suggests an association between the 10.5 kb TNF-beta allele and IDDM, and demonstrates an association between monokine responses and TNF-beta genotypes.(ABSTRACT TRUNCATED AT 400 WORDS)

Genetics of type 1 diabetes mellitus

“…[74][75][76] A number of observations indicate that class II genes cannot explain all of the MHC associations with T1D. A role for MHC complex genes other than class II genes was first suggested by Thomsen et al 77 and Pociot et al 78 by studying HLA-DR3/4 heterozygous individuals, and by Robinson et al 79 using a family study design, which to some degree eliminated the LD effects involving HLA-DQ/DR loci; however, in all these studies the number of subjects/families was small. Subsequently, several studies have supported a role for both MHC HLA class IV and class I genes in T1D predisposition.…”

“…The most studied class IV genes are tumour necrosis factor and lymphotoxin (TNFA and TNFB). 78,[80][81][82] The strongest evidence for susceptibility genes in the class I region comes from recent systematic assessment of microsatellite markers spanning this region. [83][84][85][86][87][88][89] Non-HLA encoded susceptibility to T1D HLA-encoded T1D susceptibility may account for less than 50% of the inherited disease risk and thus, there is a substantial role for non-HLA encoded susceptibility.…”

No evidence for linkage in the promoter region of the inducible nitric oxide synthase gene (NOS2) in a Danish type 1 diabetes population

“…31 The PCR-based genotyping of three polymorphisms were performed as follows: (i) Bsal RFLP: Primers: F: 5Ј GGA ATG AGT GGA CAG GGG GAG CAA A 3Ј and R: 5Ј AAG ACT GGA GCG GAG TGG CAC GAT 3Ј. Amplification: 95°C for 10 min; 35 cycles each of 95°C for 30 sec/64°C for 30 sec/72°C for 30 sec; followed by 72°C for 10 min.…”

Extensive genetic polymorphism in the human tumor necrosis factor region and relation to extended HLA haplotypes

“…Combined typing for TNFa, -b, and -c and for the Nco I RFLP could further increase the precision of this analysis by extending it to TNF haplotypes (Table 3). There is direct evidence for the involvement of TNF (or TNF deficiencies) in the etiology of several autoimmune diseases, including systemic lupus erythematosus-associated glomerulonephritis (25,35) and the pancreatic insulitis that leads to IDDM (16,(36)(37)(38)(39). In addition, a genetic factor mapping near or within the MHC class III region and acting independently of HLA-DQ has been associated with IDDM susceptibility (40).…”

“…This hypothesis has been difficult to test because of a lack of genetic markers in the locus: an extensive search for restriction fragment length polymorphisms (RFLPs) has yielded a biallelic Nco I RFLP (10-13) and a very rare EcoRI RFLP (14). In spite of its limited information content, the Nco I RFLP has already allowed some tentative associations between TNF alleles and autoimmune diseases (11,15); recent evidence also suggests that one Nco I allele correlates with increased TNF-a and reduced TNF-13 production (13,16).…”