An allelic polymorphism within the human tumor necrosis factor alpha promoter region is strongly associated with HLA A1, B8, and DR3 alleles.

The tumor necrosis factor (TNF) alpha gene lies within the class III region of the major histocompatibility complex (MHC), telomeric to the class II and centromeric to the class I region. We have recently described the first polymorphism within the human TNF-alpha locus. This is biallelic and lies within the promoter region. Frequency analysis of the TNF-alpha polymorphism, using the polymerase chain reaction and single-stranded conformational polymorphism, in HLA-typed individuals, reveals a very strong association between the uncommon TNF allele and HLA A1, B8, and DR3 alleles. This is the first association between TNF-alpha and other MHC alleles and raises the possibility that the uncommon TNF-alpha allele may contribute to the many autoimmune associations of the A1,B8,DR3 haplotype.

Urate crystals stimulate production of tumor necrosis factor alpha from human blood monocytes and synovial cells. Cytokine mRNA and protein kinetics, and cellular distribution.

Crystals of monosodium urate (MSU) provide a dose-dependent stimulus for the production by human blood monocytes of tumor necrosis factor (TNF), a cytokine with proinflammatory properties; TNF activity was inhibited selectively by monoclonal antibody to TNF alpha. Biologically active cell-associated TNF activity peaked at 3 h and was exceeded at 6 h by extracellular activity, which peaked at 12-18 h. Comparable kinetics were observed with immunoreactive TNF alpha. TNF alpha mRNA accumulation in monocytes stimulated with MSU crystals appeared as a single peak at 2-4 h, kinetics compatible with rapid production of a short half-life transcript. In contrast, crystals of calcium pyrophosphate or of hydroxyapatite did not stimulate significant production of TNF or of message. Fresh tophaceous material from a patient with gout contained significant levels of TNF alpha and cells cultured from the tophus produced TNF alpha in vitro. In rheumatoid synovial cells, spontaneous release of TNF alpha was increased by in vitro exposure to MSU crystals. Taken together with earlier work, these results support an expanded view of gouty inflammation in which the crystal-stimulated production of cytokines provides a crucial link between crystal deposition and many of the clinical and pathological facts of both acute and chronic gouty arthritis.

Kinetics of IL1 beta mRNA and protein accumulation in human mononuclear cells.

Interleukin 1 beta (IL1 beta) is an inducible polypeptide with many roles in host defence and homoeostasis. It has also been implicated as a mediator of infectious, inflammatory and autoimmune diseases, and the kinetics of its production are relevant to an understanding of the pathogenesis of these conditions. We report here the time-course of IL1 beta production in human adherent monocytes. Both IL1 beta protein and mRNA were measured following cell activation with bacterial endotoxin (lipopolysaccharide; LPS), and pro-inflammatory crystals of monosodium urate (MSU), which cause arthritis and kidney disease. We also tested other crystal types associated with arthritis, namely hydroxylapatite and calcium pyrophosphate dihydrate. IL1 was absent from unstimulated cells, but IL1 beta mRNA accumulated rapidly after LPS or MSU stimulation and was associated with the later appearance of intracellular IL1 beta protein which was subsequently released from the cells (60% at 9 h). The other crystals failed to induce significant IL1 production. Our findings support the view that production of IL1 beta in human mononuclear cells is based on rapid translation of an inducible pool of mRNA and that no pre-formed mRNA or intracellular protein exists in normal blood monocytes. Further, although IL1 beta is translated without a conventional leader sequence, it is translocated extracellularly with the kinetics of a secretory protein.

Genetics of tumour necrosis factor-alpha in autoimmune, infectious, and neoplastic diseases.

Tumour necrosis factor-alpha (TNF-alpha) is a potent immunomediator and proinflammatory cytokine that has been implicated in the pathogenesis of a large number of human diseases. The location of its gene with the major histocompatibility complex and biological activities have raised the possibility that polymorphism within this locus may contribute to the genetic association of this region of the genome with a wide range of autoimmune and infectious diseases. This review discusses the genetics of the TNF locus in several of the major autoimmune diseases and also in relation to infectious and neoplastic diseases. There is increasing evidence that genetic variation within the TNF locus is important in determining susceptibility to, or severity of, a significant number of these conditions.

Interleukin-1 cluster and tumor necrosis factor-alpha gene polymorphisms in polymyalgia rheumatica.

OBJECTIVE: To investigate whether polymorphisms in the interleukin (IL)-1 locus (human chrom. 2q13) and TNF-alpha gene are associated with susceptibility to or severity of polymyalgia rheumatica (PMR). METHODS: The study included 92 consecutive PMR patients diagnosed over a 5-year period who were prospectively followed-up for at least one year and 79 healthy controls over the age of 50 residing in the same area. All the patients and controls were Caucasians of Italian origin. We tested the allelic distribution of IL-1A (+4845), IL-B (-511), IL-B (+3954), IL-1RN Intron 2 VNTR and TNFA (-308). Frequencies were compared in the patient and control groups. RESULTS: A statistically significant association between PMR patients and the IL1RN*2 allele in the homozygous state was found [OR 8.46 (95% CI 1.05-68.31)]. The polymorphisms in the other genes of the IL-1 gene cluster did not reveal any association with PMR when compared with controls. A weak association between PMR patients and the TNF2 allele was also present [OR 2.09 (95% CI 1.0-4.17)]. None of the gene variants studied was associated with the disease severity of PMR. CONCLUSION: Our findings show that IL1RN*2 allele, particularly in the homozygous state, is associated with susceptibility to, but not with the severity of, PMR.

Absence of the association with CC chemokine receptor 5 polymorphism in polymyalgia rheumatica.

OBJECTIVE: Elevated RANTES serum levels are present in polymyalgia rheumatica (PMR) patients with active disease. Chemokines may contribute to the inflammatory PMR process through their binding to CC chemokine receptor 5 (CCR5). The aim of this study was to examine if the 32 base pair deletion allele in CCR5 (CCR5 delta 32 allele) might be associated with PMR susceptibility and influence the disease outcome. METHODS: We enrolled 88 consecutive patients with PMR residing in the Reggio Emilia area (Italy) who had a follow-up duration of at least one year. As a control group we used 86 healthy blood donors from the same geographic area. The CCR5 genotype of all PMR patients and controls was studied by polymerase chain reaction amplification of the region which includes the 32 deletion (CCR5 delta 32). RANTES serum levels were measured by commercial ELISA kits in CCR5 delta 32 heterozygous and CCR5 homozygous PMR patients at diagnosis before starting corticosteroid therapy and again after 6 months of therapy, as well as in 28 healthy subjects over 50 years of age. RESULTS: Frequencies of the CCR5 and CCR5 delta 32 alleles in patients and controls did not differ significantly. Homozygosity for CCR5 delta 32 was not detected in PMR patients and was detected in only one of the controls. No significant differences were observed between the patients carrying the CCR5 delta 32 allele and those homozygous for the normal CCR5 allele when we compared sex, presence of distal synovitis and systemic signs and/or symptoms, initial and cumulative prednisone dose, duration of therapy, ESR at diagnosis, frequency of relapse/recurrence and RANTES serum levels at diagnosis and after 6 months of corticosteroids. CONCLUSION: These results indicate that the frequency of the 32 deletion of the CCR5 receptor was not significantly different between PMR patients and healthy controls, and this genotype does not appear to be associated with the susceptibility to or severity of PMR.

Genetic polymorphisms of the IL-1alpha and IL-1beta genes in African-American LJP patients and an African-American control population.

BACKGROUND: A functional polymorphism of the interleukin-1 beta (IL-1beta) gene has been proposed to be a risk factor for periodontitis. In adult forms of periodontitis, non-smokers of northern European heritage carrying the "2" allele of the IL-1alpha-889 and the IL-1beta +3953 RFLPs in either the heterozygous or the homozygous state at both loci were observed to have a greater risk for developing severe periodontitis. Studies of early-onset periodontitis (EOP) found that allele "1" of both IL-1alpha-889 and IL-1beta +3953 was transmitted more frequently with the EOP phenotype. The purpose of the present study was to determine the prevalence of the IL-1alpha and IL-1beta genotype polymorphisms in an African-American (AA) control population and in 37 African-Americans with localized juvenile periodontitis (LJP). METHODS: The IL-1alpha +4845 and IL-1beta +3953 loci were genotyped by PCR amplification, followed by restriction enzyme digestion and gel electrophoresis. The IL-1alpha +4845 locus, in linkage disequilibrium (>99%) with IL-1alpha-889, was genotyped because it is technically easier. Data were analyzed using r x c contingency tables. RESULTS: The IL-1beta +3953 allele "1" was carried by >99% of the AA control population and by 100% of the AA LJP group, with most individuals being homozygous 1,1. The prevalence of the composite genotype with at least one allele "2" at each of the IL-1beta +3953 and IL-1alpha +4845 loci was 14% (AA control group) and 8% (AA LJP group). CONCLUSIONS: Given the high frequency of the IL-1beta allele "1" in the African-American population, it would appear that knowledge of this +3953 polymorphism would provide little diagnostic or predictive information for LJP.

Interleukin-1 genetic association with periodontitis in clinical practice.

BACKGROUND: Periodontitis is a bacterial disease modified by multiple risk factors. The pro-inflammatory cytokine interleukin- (IL-1) is a key regulator of the host responses to microbial infection and a major modulator of extracellular matrix catabolism and bone resorption. It has been reported that variations in the IL-1 gene cluster on chromosome 2 are associated with increased susceptibility to severe adult periodontitis. METHODS: The present study evaluated the association between a composite IL-1 genotype, including allele 2 at each of two loci (IL-1A +4845 plus IL- B +3954), and a broad spectrum of periodontally healthy to diseased patients in a population that is typically encountered in a dental practice setting. Ninety patients, non-smokers or former smokers with less than 10 pack-year (pk/yr) history, were recruited from a private dental practice. The major outcome variable was bone loss determined by computerized linear measurements of radiographs. Genotypes were analyzed from finger-stick blood samples using previously reported methods. RESULTS: Multivariate logistic regression models demonstrated that patient age, former smoking history, and the IL-1 genotype were significantly associated with severity of adult periodontitis. For non-smokers or former light smokers (<5 pk/yr), IL-1 genotype positives were at increased odds ratio of having moderate to severe periodontal disease of 3.75 (95% CI: 1.04-13.50) to 5.27 (95% CI: 1.23-22.70), depending on ethnicity, compared to IL-1 genotype negatives. Former moderate smokers (>5 pk/yr and <10 pk/yr) who were IL-1 genotype negative were at increased odds ratio of having moderate to severe periodontal disease of 7.43 (95% CI: 1.20-46.20) compared to non-smokers or former light smokers who were IL-1 genotype negative. In addition, past smoking history was also a significant effect modifier as demonstrated by the statistically significant interaction between past smoking history status and IL-1 genotype status. CONCLUSIONS: This study demonstrates that the composite IL-1 genotype is significantly associated with the severity of adult periodontitis. It also confirmed that both IL-1 genotyping and smoking history provide objective risk factors for periodontal disease in a private practice environment.

Low prevalence of a periodontitis-associated interleukin-1 composite genotype in individuals of Chinese heritage.

BACKGROUND: Polymorphisms in the interleukin-1 (IL-1) gene cluster have been associated with an increased risk of developing certain diseases. A specific composite genotype of IL-1A and IL-1B polymorphisms, consisting of allele 2 of both IL-1A +4845 and IL-1B +3954 (formerly +3953) has been associated with an increased risk of severe adult periodontitis. Approximately 30% of the European population carry this genotype. The prevalence of the above IL-1A and IL-1B composite genotype in populations of different ethnic origins is unknown. Therefore, the primary aim of this study was to determine the prevalence of the IL-1 composite genotype in individuals of Chinese heritage, since epidemiologic studies indicate that periodontitis is widespread among ethnic Chinese. An additional aim was to evaluate if there was an association between the composite genotype and the severity of periodontal disease. METHODS: A convenience sample of 300 volunteers of Chinese heritage (ages 21 to 69 years) received a periodontal examination including full-mouth clinical attachment loss measurements, probing depths, plaque index scores, and bleeding on probing. Blood was collected from a fingerstick and placed on a blotting paper card. The blood samples were analyzed for IL-1A +4845 and IL-1B +3954 polymorphisms using polymerase chain reaction (PCR)-based methods. RESULTS: Only 7 of the 300 subjects (2.3%) carried the composite IL- 1 genotype consisting of allele 2 of both IL-1A +4845 and IL-1B +3954. Allele 2 of the IL-1A +4845 polymorphism was carried by 17.0% (51/300) of the subjects; of these, only 2 were homozygous. Allele 2 of the IL-1B +3954 polymorphism was much rarer with only 3.3% (10/300) of the study population carrying this marker. All of the people who carried the IL-1B polymorphism were heterozygous. Too few of the subjects were positive for the IL-1 composite genotype to establish any relationship with the susceptibility to periodontitis. CONCLUSIONS: It was concluded that the prevalences of both IL-1A and IL-1B polymorphisms are dramatically lower in Chinese than those reported for Europeans. Findings from this study bring into question the usefulness of the composite genotype of allele 2 of both IL-1A +4845 and IL-1B +3954 as a method for determining the susceptibility of Chinese patients to adult periodontitis.

The influence of interleukin gene polymorphism on expression of interleukin-1beta and tumor necrosis factor-alpha in periodontal tissue and gingival crevicular fluid.

BACKGROUND: A specific composite genotype of the polymorphic interleukin-1 (IL-1) gene cluster has recently been associated with severe periodontitis. One polymorphism of the composite periodontitis-associated genotype (PAG) has been functionally linked with expression of high levels of IL-1. The purpose of this study was to test whether gingival crevicular fluid (GCF) levels of IL-1beta and tumor necrosis factor-alpha (TNFalpha), and gingival tissue levels of IL-1alpha, IL-1beta, and TNFalpha correlate with PAG, and to examine the effect of conservative periodontal therapy on these levels. METHODS: Twenty-two adults with moderate to advanced periodontal disease were enrolled. Polymerase chain reaction amplification and restriction enzymes were used to identify specific polymorphisms from peripheral blood samples. GCF samples were collected at baseline and 3 weeks following conservative treatment and analyzed by ELISA for IL-1beta and TNFalpha. An interproximal gingival biopsy was collected at baseline and follow-up and analyzed for IL-1alpha, IL-1beta, and TNFalpha by ELISA. RESULTS: The genotyping identified 7 as PAG(+) and 15 as PAG(-). The 2 groups were comparable in terms of existing periodontitis and age. In shallow sites (<4 mm), total IL-1beta in GCF was 2.5 times higher for PAG(+) patients prior to treatment (P=0.03), and 2.2 times higher after treatment (P=0.04), while differences were less apparent in deeper sites. Following treatment, a reduction in IL-1beta concentration in GCF was seen for PAG(-) but not for PAG(+) patients. While not statistically significant, a trend was observed in mean tissue levels of IL-1beta which were 3.6 times higher in PAG(+) versus PAG(-) patients (P=0.09). CONCLUSIONS: These data suggest that PAG(+) patients may demonstrate phenotypic differences as indicated by elevated levels of IL-1beta in GCF.

Aortic connective tissue in atherosclerotic aorta--a biochemical study.

Biochemical analysis of the extracellular matrix of human aortas was performed on samples of ascending and descending aortas affected by atherosclerosis in comparison with a control group of nonatherosclerotic aortas. Ulcerated or heavily calcified atheromas were excised and excluded from the analysis in order to differentiate biochemical alterations leading to the formation of atheromas from those due to complications of already formed atheromas. Our results show that the development of atheromas brings about an extensive destruction of elastic fibers and muscular cells, and their place is occupied by other components of the extracellular matrix, most notably, collagen, non-uronic sugars, water, and lipids, which were found significantly increased.

Biochemical analysis of dermal connective tissue in subjects affected by primary uncomplicated varicose veins.

Biochemical analysis of dermal connective tissue was carried out in 14 subjects affected by primary uncomplicated varicose veins and 14 controls. Skin samples were taken, according to fixed criteria, from operation pieces of total mastectomy for breast cancer. The results suggest that the dermal tissue in these subjects is just thinner than that of controls, confirming previous similar clinical findings. The elective reduction of the collagen content observed, unassociated with changes of other components of the dermal connective tissue, brings evidence for a systemic biochemical defect of the extracellular matrix i.e. a collagen defect affecting the entire body structure and not only the varicose or pre-varicose veins of the lower limbs.

Aortic connective tissue in ageing--a biochemical study.

The biochemical analysis of samples of aortic connective tissue was carried out in 22 subjects from 9 to 84 years old. Aortic samples were taken at necropsy performed after sudden or, more often, traumatic death. The results suggest that aging of the aorta is accompanied by an increase both in collagen content and in total sugar content when expressed as mg/cm2 while the elastin content, when expressed in the same way, does not undergo any variation.

Evidence of a pharmacogenomic response to interleukin-l receptor antagonist in rheumatoid arthritis.

Biological activity of the IL-1 system depends on the balance between two proinflammatory proteins (IL-1alpha and IL-1beta) and the related anti-inflammatory protein, the IL-1 receptor antagonist (IL-1Ra). The genes for these proteins lie within 430 kb on human chromosome 2. Based on a clinical trial of human recombinant IL-1ra in rheumatoid arthritis, we tested whether IL-1 genotype might be related to the likelihood of response to anti-IL-1 therapy. A positive response was defined as a reduction of at least 50% in the number of swollen joints by week 24, following treatment with either 150 mg/day IL-1ra or placebo. The response rate to treatment, independent of genotype, was 48% (44/91). A highly significant association was found between carriage of the rarer allele at IL1A(+4845) and response to treatment (P=0.0009; OR=4.85 (1.85,12.70)). The response rate in patients carrying this allele was 63.4% compared with 26.3% in noncarriers. A weaker association was found for IL1B(+3954) (P=0.02). There was a highly significant interaction between treatment (150 mg/day or placebo) and the composite genotype across IL1A(+4845) and IL1B(+3954) (P=7.6 x 10(-5)). No associations with IL-1 genotypes were found in patients receiving placebo. Thus, a significant pharmacogenomic effect was found in the treatment of RA patients with recombinant IL-1ra.

Tumour necrosis factor in synovial exudates.

The actions of tumour necrosis factor (TNF) include resorption of bone and cartilage, suggesting a potential role in the pathogenesis of arthritis. TNF activity was looked for in synovial fluids from 137 patients with different rheumatic diseases. Unfractionated samples were tested in the L929 bioassay. Significant TNF activity that was neutralised by monoclonal antibody to TNF alpha occurred in 13 (30%) of 44 samples. Raised TNF levels were not associated with any particular disease type or routine laboratory markers of inflammation but were related to disease duration in osteoarthritis. The finding of biologically active TNF in symptomatic joints of arthritic patients supports the idea that it may contribute to the pathogenesis of joint damage in chronic rheumatic diseases.

Polymorphic tandem repeat region in interleukin-1 alpha intron 6.

Analysis of polymerase chain reaction amplified products from the sixth intron of the human interleukin-1 alpha gene reveals a high polymorphism (polymorphism information content = 0.51) in a Caucasian population. Altogether, seven alleles have been defined ranging from 620 to 1220bp. This polymorphism is probably attributable to a variable number of 46-bp tandem repeats, each containing potential regulatory sequences.

Interleukin 1: the first interleukin.

The name 'interleukin' and the designation of interleukin 1 (IL-1) derived from the Second International Lymphokine Workshop held in Switzerland in 1979. Since then interest in the original interleukin (IL-1) has increased exponentially as measured by the numbers of publications and meetings. The main reasons for this can be seen in the accompanying centrefold. The perception of IL-1 as a biological mediator in every organ system has attracted scientists from widely different backgrounds into this area and a steady succession of important and often surprising insights into IL-1 biology has ensured that interest has been sustained at a high level. This overview of the biology of IL-1 on the tenth anniversary of its turbulent life has been compiled by Franco di Giovine and Gordon Duff. It is of necessity selective and biased towards human IL-1 and begins with some general points (mainly cautionary) as a backdrop to the centrefold.