Helicobacter pylori infection is associated with a variety of clinical outcomes including gastric cancer and duodenal ulcer disease. The reasons for this variation are not clear, but the gastric physiological response is influenced by the severity and anatomical distribution of gastritis induced by H. pylori. Thus, individuals with gastritis predominantly localized to the antrum retain normal (or even high) acid secretion, whereas individuals with extensive corpus gastritis develop hypochlorhydria and gastric atrophy, which are presumptive precursors of gastric cancer. Here we report that interleukin-1 gene cluster polymorphisms suspected of enhancing production of interleukin-1-beta are associated with an increased risk of both hypochlorhydria induced by H. pylori and gastric cancer. Two of these polymorphism are in near-complete linkage disequilibrium and one is a TATA-box polymorphism that markedly affects DNA-protein interactions in vitro. The association with disease may be explained by the biological properties of interleukin-1-beta, which is an important pro-inflammatory cytokine and a powerful inhibitor of gastric acid secretion. Host genetic factors that affect interleukin-1-beta may determine why some individuals infected with H. pylori develop gastric cancer while others do not.

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Interleukin-1 polymorphisms associated with increased risk of gastric cancer

https://www.doils.net/v1/links/836150.pdf

n−3 Polyunsaturated fatty acids, inflammation, and inflammatory diseases

Context.— Aspirin has been widely used to prevent myocardial infarction and ischemic stroke but some studies have suggested it increases risk of hemorrhagic stroke. Objective.— To estimate the risk of hemorrhagic stroke associated with aspirin treatment. Data Sources.— Studies were retrieved using MEDLINE (search terms, aspirin, cerebrovascular disorders, and stroke), bibliographies of the articles retrieved, and the authors’ reference files. Study Selection.— All trials published in English-language journals before July 1997 in which participants were randomized to aspirin or a control treatment for at least 1 month and in which the incidence of stroke subtype was reported. Data Extraction.— Information on country of origin, sample size, duration, study design, aspirin dosage, participant characteristics, and outcomes was abstracted independently by 2 authors who used a standardized protocol. Data Synthesis.— Data from 16 trials with 55 462 participants and 108 hemorrhagic stroke cases were analyzed. The mean dosage of aspirin was 273 mg/d and mean duration of treatment was 37 months. Aspirin use was associated with an absolute risk reduction in myocardial infarction of 137 events per 10 000 persons (95% confidence interval [CI], 107-167;P,.001) and in ischemic stroke, a reduction of 39 events per 10 000 persons (95% CI, 17-61; P,.001). However, aspirin treatment was also associated with an absolute risk increase in hemorrhagic stroke of 12 events per 10 000 persons (95% CI, 5-20; P,.001). This risk did not differ by participant or study design characteristics. Conclusions.— These results indicate that aspirin therapy increases the risk of hemorrhagic stroke. However, the overall benefit of aspirin use on myocardial infarction and ischemic stroke may outweigh its adverse effects on risk of hemorrhagic stroke in most populations.

A Meta-analysis of Randomized Controlled Trials

Although specific bacteria, dental plaque, and age are associated with periodontal disease, there are currently no reliable predictors of periodontitis severity. Studies in twins have suggested a genetic contribution to the pathogenesis of periodontitis, but previous attempts to identify genetic markers have been unsuccessful. The pro-inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) are key regulators of the host responses to microbial infection. IL-1 is also a major modulator of extracellular matrix catabolism and bone resorption. We report a specific genotype of the polymorphic IL-1 gene cluster that was associated with severity of periodontitis in non-smokers, and distinguished individuals with severe periodontitis from those with mild disease (odds ratio 18.9 for ages 40-60 years). Functionally, the specific periodontitis-associated IL-1 genotype comprises a variant in the IL-1B gene that is associated with high levels of IL-1 production. In smokers severe disease was not correlated with genotype. In this study, 86.0% of the severe periodontitis patients were accounted for by either smoking or the IL-1 genotype. This study demonstrates that specific genetic markers, that have been associated with increased IL-1 production, are a strong indicator of susceptibility to severe periodontitis in adults.

The interleukin-1 genotype as a severity factor in adult periodontal disease

Tumour-necrosis factor-alpha (TNF-alpha) is believed to have an important role in the pathogenesis of severe infectious disease and fatal cerebral malaria is associated with high circulating levels of this cytokine. In a large case-control study in Gambian children we find that homozygotes for the TNF2 allele, a variant of the TNF-alpha gene promoter region, have a relative risk of 7 for death or severe neurological sequelae due to cerebral malaria. Although the TNF2 allele is in linkage disequilibrium with several neighbouring HLA alleles, we show that this disease association is independent of HLA class I and class II variation. These data suggest that regulatory polymorphisms of cytokine genes can affect the outcome of severe infection. The maintenance of the TNF2 allele at a gene frequency of 0.16 in The Gambia implies that the increased risk of cerebral malaria in homozygotes is counterbalanced by some biological advantage.

Variation in the TNF-alpha promoter region associated with susceptibility to cerebral malaria.

In the present study we searched for restriction fragment length polymorphisms (RFLP) in the human interleukin-1 beta (IL-1 beta) gene and for correlations to monocyte (Mo) function in non-related healthy donors and insulin-dependent diabetic patients. We demonstrated a diallelic polymorphism with the restriction enzyme TaqI consisting of fragments of 9.4 kb and 13.4 kb. No differences in allele or genotype frequencies of this RFLP were observed between randomly selected controls and randomly selected patients with insulin-dependent diabetes mellitus (IDDM). However, when analysing IDDM patients negative for HLA-DR3 and -DR4, our data demonstrate that the 13.4 kb allele is more frequent in this group compared to a matched control group. The functional impact of this RFLP was studied by analysing in vitro stimulated Mo IL-1 beta response. An IL-1 beta allele dosage effect on secretory capacity was observed after LPS-stimulation: 13.4/13.4 kb homozygous individuals secreted significantly more IL-1 beta than 9.4/13.4 kb heterozygous individuals, who secreted significantly more than 9.4/9.4 kb homozygous individuals. Analyses of supernatants from LPS-stimulated Mo cultures from individuals with each TaqI IL-1 beta genotype revealed no differences in the mouse thymocyte co-stimulatory assay when compared on a molar basis, indicating that the TaqI polymorphism gave rise only to quantitative differences in expression levels and probably not to a mutant IL-1 beta.(ABSTRACT TRUNCATED AT 250 WORDS)

A Taql polymorphism in the human interleukin-1β (IL-1β) gene correlates with IL-1β secretion in vitro

We have investigated the correlation between different tumor necrosis factor (TNF) and class II major histocompatibility complex alleles in the lipopolysaccharide- or phytohemagglutinin-induced secretion of TNF-α and TNF-β by human monocytes and peripheral blood mononuclear cells in 87 unrelated Danish male individuals. Significant differences in TNF-α secretory capacity between TNF Ncol restriction fragment length polymorphisms, TNFa and TNFc micro-satellite alleles and DR alleles were identified. No correlation with TNF-β secretory capacity was found for any of the markers studied. TNF genotyping allowed us to define four extended HLA haplotypes which correlate with TNF-α secretory capacity. Two of these are DR4 positive: DQw8, DR4, TNFB*1, TNFa6, B44, A2 and DQw8, DR4, TNFB*2, TNFa2, B15, A2. Individuals carrying the TNFB*2, TNFa2 haplotype had a higher TNF-α secretory capacity than those carrying the TNFB*1, TNFa6 haplotype. In a group of DR3/DR4 heterozygous patients with insulin-dependent diabetes mellitus (IDDM), the frequency of the TNFa2 allele was higher than in HLA-DR matched controls, whereas theTNFa6 allele was more frequent in control individuals. In the DR3/DR4 heterozygous diabetic group 12/26 had the alleles combination DQw8, DR4 (Dw4), C4A3, TNFB*2, TNFa2, B15, whereas only 1/18 controls had this haplotype. This diabetogenic haplotype is identical to the DR4 haplotype which correlates with a higher TNF-α response. These observations suggest a direct role for the TNF locus in the pathogenesis of IDDM.

Association of tumor necrosis factor (TNF) and class II major histocompatibility complex alleles with the secretion of TNF-a and TNF-0 by human mononuclear cells: a possible link to insulin-dependent diabetes mellitus

Cytokine and free radicals as effector molecules in the destruction of pancreatic beta cells.

The pathogenetic mechanisms leading to beta-cell destruction and insulin-dependent diabetes mellitus (IDDM) are major histocompatibility complex (MHC) nonrestricted and are MHC associated and beta-cell specific. The macrophage peptide hormone interleukin 1 (IL-1) may be the primary MHC-nonrestricted beta-cell-destructive molecule. Beta-Cell death most likely results from free radical induction by IL-1. Thus, islet cell-specific antibodies and cytotoxic T-lymphocytes are secondary in importance and time. The potentiation of IL-1 effects on beta-cells by tumor necrosis factor alpha (TNF), another macrophage hormone controlled by a gene in the HLA region on chromosome 6, may account for the MHC association of IDDM. In the experimental model of IDDM etiopathogenesis described, release of beta-cell antigen, processed and presented by macrophages to helper T-lymphocytes, initiates a self-perpetuating and self-limiting circuit of cytokine production of which IL-1 is beta-cell cytotoxic. As postulated, the IL-1 effect is potentiated by TNF, whereas IL-1 and/or TNF production is controlled in a quantitative way by HLA-D genes.

Mechanisms of pancreatic beta-cell destruction in type I diabetes

HLA-class III region genes may be associated with susceptibility to insulin-dependent diabetes mellitus (IDDM). In this study an Ncol polymorphism of the tumour necrosis factor beta (TNF-β) gene, which is positioned next lo the tumour necrosis factor alpha (TNF-α) gene in the HLA class 111 region, was detected by restriction fragment length polymorphism (RFLP). This polymorphism has previously been reported lo be located in the TNF-α 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-β 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-β 5.5-kb allele to BS, DR3 haplotypes, and of the TNF-β 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 < 0.0079), In HLA-DR3,4-atid DQw8-positive persons, the DR3 haplotypes carried the 10.5-kb allele ihrcL- times more frequently in IDDM patients than in controls, suggesting that the 10.5-kb allele when present on DR3 haplotyes may contribute lo susceplibility to IDDM in DR3.4 heterozygous individuals, A contributory role of the Hl.5-kballele in genetic IDDM susceptibility was supported by the sibpair analysis, in which all were TNF-/1 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 bela (IL-1/J)and TNb-α in relation lo the Ncol TNF-/f gene polymorphism. The LPS- and PHA stimulated Mo IL-l/f and TNF-a: secretions were significantly lower for the TNF-β 5.5.10,5 kb heterozygous individuals than for TNF-β 10.5 kb homozygous individuals. Furthermore, the Mo IL-1β and TNF-a secretions of IDDM patients were significantly higher than the Mo secretions of TNF-β genolype-matched healthy controls.



This study suggests an association between the 10.5 kb TNF-β allele and IDDM, and demonstrates an association between monokine responses and TNF-β genotypes. These observations may have implications for understanding the pathogenesis of HLA-associated autoimmune diseases including IDDM.

J. Mølvig

Papers

A Taql polymorphism in the human interleukin-1β (IL-1β) gene correlates with IL-1β secretion in vitro

Association of tumor necrosis factor (TNF) and class II major histocompatibility complex alleles with the secretion of TNF-a and TNF-0 by human mononuclear cells: a possible link to insulin-dependent diabetes mellitus

Cytokine and free radicals as effector molecules in the destruction of pancreatic beta cells.

Mechanisms of pancreatic beta-cell destruction in type I diabetes

A tumour necrosis factor beta gene polymorphism in relation to monokine secretion and insulin-dependent diabetes mellitus.