The human IL-1 receptor antagonist gene (IL1RN) maps to chromosome 2q14-q21, in the region of the IL-1 alpha and IL-1 beta loci

Genetic variability of innate immunity impacts human susceptibility to fungal diseases

Fungi are a major threat in immunocompromised patients. Despite presenting similar degrees of immunosuppression, not all individuals at-risk ultimately develop fungal diseases. The traditional view of immune suppression as a key risk factor for susceptibility to fungal infections needs to be accommodated within new conceptual advances on host immunity and its relationship to fungal disease. The critical role of the immune system emphasizes the contribution of host genetic polymorphisms to fungal disease susceptibility. This review highlights the present knowledge on innate immunity genetics that associates with susceptibility to fungal diseases.

Polymorphism of the interleukin 1 receptor antagonist (IL1Ra) gene and placental abruption

Candidate genes with a possible involvement in placental abruption are mainly those related to thrombophilia and preeclampsia. Some reports have shown by placental histologic investigation that increased risk of placental abruption is associated with prolonged inflammation. The polymorphic allele A2 in the gene coding for interleukin 1 receptor antagonist (IL1Ra) has been associated in various diseases of autoimmune or inflammatory nature. In obstetrics, previous research data has linked altered IL1Ra protein production with placental pathology and some severe pregnancy complications. In this study, we have determined whether IL1Ra gene polymorphism is associated also with an increased risk of placental abruption. The study involved 116 women with placental abruption and 112 healthy control pregnant women who were genotyped for polymorphism of the IL1Ra gene. The genotype and allele frequencies were assessed between the two groups and also compared with those in the general population. The frequency of the A2 allele was 28.0% among cases and 33.0% in controls (p=0.29), both similar to that in the general population (28.9%). In addition, the genotype distribution of IL1Ra polymorphisms was similar in both groups. Interestingly, there were a relatively higher number of cases with allele A3 (n=4; 1.7%) compared with the controls (0.4%) and the general population (1.0%) but the difference was not statistically significant. We conclude that there is no significant difference in IL1Ra polymorphisms between patients with and without placental abruption.

Interleukin-1beta: a bridge between inflammation and excitotoxicity?

Interleukin-1 (IL-1) is a proinflammatory cytokine released by many cell types that acts in both an autocrine and/or paracrine fashion. While IL-1 is best described as an important mediator of the peripheral immune response during infection and inflammation, increasing evidence implicates IL-1 signaling in the pathogenesis of several neurological disorders. The biochemical pathway(s) by which this cytokine contributes to brain injury remain(s) largely unidentified. Herein, we review the evidence that demonstrates the contribution of IL-1beta to the pathogenesis of both acute and chronic neurological disorders. Further, we highlight data that leads us to propose IL-1beta as the missing mechanistic link between a potential beneficial inflammatory response and detrimental glutamate excitotoxicity.

Predisposition of genetic polymorphism with the risk of urolithiasis

Urolithiasis is a relevant clinical problem with a subsequent burden for health system. The aim of this review is to provide recent progress made using genetic polymorphisms to define pathophysiology, to identify persons at risk for kidney stone disease and to predict treatment response. Population case-control studies are useful both as an alternative and an adjunct as compared to family studies. These involve either whole genome scanning or candidate gene approaches. While whole genome scanning is likely to be widely used in future, at present, candidate gene studies are more feasible. When performing candidate gene case-control studies factors such as study design, methods for recruitment of case and controls, selection of candidate genes, functional significance of polymorphisms chosen for study and statistical analysis require close attention to ensure that only genuine associations are detected. Some of the significant genes that play role in stone formation include calcitonin receptor gene (CTR), vitamin D receptor (VDR), Urokinase, Interleukin, (IL-1β, IL-Ra), E-Cadherin, Androgen & oestrogen receptor gene, vascular endothelial growth factor (VEGF) and Arginine p21. In our case-control study we studied CTR, VDR, Urokinase, IL-1β(-511 and +3954), IL-Ra from north India and predict that VDR, IL-β (-511) and IL-1Ra gene may be used as a possible genetic marker for earlier detection in patients who are at risk for calcium oxalate stone disease. Further, linkage disequilibrium and haplotype structure of a certain candidate gene is important for association analysis. When a certain polymorphic allele has been found to be associated with disease, it is further explained on basis of LD and haplotype structure by one or more other alleles. Once it is determined which haplotype carries the risk allele, by means of molecular biological functional analyses, the variants on that haplotype allele truly causing the effect can be determined.

Association of interleukin-4 and interleukin-1 receptor antagonist gene polymorphisms and risk of benign prostatic hyperplasia

OBJECTIVES

The genetic and cellular processes involved in the etiopathology of benign prostatic hyperplasia (BPH) are unknown. Although evidence of BPH as an immune-mediated disease distinct from prostate cancer is growing, the cytokine gene polymorphisms associated with the risk of BPH have been explored less. The purpose of this study was to investigate the genetic association of polymorphisms of important cytokine genes (IL-4 and IL-1Ra) with the risk of BPH in a case-control study of a North Indian population.

METHODS

The IL-4 and IL-1Ra gene polymorphisms were genotyped with variable number of tandem repeats-polymerase chain reaction in 150 patients with BPH and normal healthy controls. On the basis of their response to combined therapy of alpha-adrenergic inhibitor plus 5-alpha-reductase inhibitor, patients were grouped as responders and nonresponders. The genotype distribution and allelic frequencies between the patients and controls were compared, and odds ratios with 95% confidence intervals were calculated using Statistical Package for Social Sciences software, version 11.5.

RESULTS

The difference in genotype frequency distribution for the IL-4 and IL-1Ra gene polymorphisms between the BPH and control groups were statistically significant (P <0.05). A significant difference (P <0.05) was also observed between the responder and nonresponder groups in the IL-4 gene variants.

CONCLUSIONS

IL-4 and IL-1Ra gene polymorphisms are associated with the risk of BPH. This study for the first time has demonstrated an association between the IL-4 polymorphism and BPH and particularly influences the therapeutic response of patients.

IL1 gene cluster polymorphisms and its haplotypes may predict the risk to develop invasive pulmonary aspergillosis and modulate C-reactive protein level

OBJECTIVE

The aim of this study was to determine whether interleukin-1 alpha (IL1alpha), interleukin-1 beta (IL1beta), and IL1 receptor antagonist (IL1Ra) polymorphisms are implicated in invasive pulmonary aspergillosis (IPA) pathogenesis.

MATERIALS AND METHODS

Subjects comprised 110 hematological patients and 148 healthy controls. Genotypic and allelic frequencies were similar between hematological patients and controls. IPA was diagnosed in 59 of the 110 patients according to consensus criteria published by the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group (EORTC/IFICG).

RESULTS AND DISCUSSIONS

Individual locus analysis showed that IL1alpha and IL1Ra polymorphisms were not associated with the presence of IPA (p = 0.560 and p = 0.680, respectively). However, a trend towards a higher presence of IL1beta( - ) (511TT) genotype (or IL1beta(-511T) allele) in the IPA group than in the non-IPA patient group (p = 0.092 and p = 0.095, respectively) was found. Haplotype analysis revealed that VNTR2/-889C/-511T haplotype was strongly associated with susceptibility to develop IPA infection (p = 0.020). Haplotype analysis also showed an association between VNTR2/-889C/-511C haplotype and resistance to IPA infection (p = 0.028). Furthermore, patients with IL1Ra VNTR2/2 and IL1beta(-511)T/T genotypes had a higher positive serum galactomannan percentage versus patients with other genotypes. Finally, C-reactive protein (CRP) production was significantly associated with IL1 gene cluster polymorphisms, although CRP values were similar between IPA and non-IPA groups.

CONCLUSION

These findings indicate a critical role of IL1 gene cluster polymorphisms in the susceptibility to IPA infection and CRP production.

Potential influence of interleukin-1 haplotype IL-1 beta-511*T-IL-1RN*1 in conferring low risk to middle third location of esophageal cancer: a case-control study

Interleukin (IL)-1 gene polymorphisms affect several inflammatory diseases, including cancer. Therefore, we studied genetic association of biallelic (-511C>T) polymorphism of IL-1 beta and 86-bp VNTR polymorphism of IL-1RN in 159 patients with esophageal cancer (EC) and 194 age- and gender-matched healthy controls. Genetic analysis for IL-1 polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism. The frequencies of IL-1 beta (-511C>T) and IL-1RN (variable number tandem repeat) genotypes, alleles, and haplotypes did not differ significantly between patients and controls. However, IL-1 beta -511TT genotype and T1+ haplotype combination illustrated low risk for disease at the middle third location of the tumor (odds ratio [OR] = 0.27; 95% confidence interval [CI] = 0.11-0.62; p = 0.002; OR = 0.462; 95% CI = 0.253-0.845, p = 0.01). In conclusion, subjects with IL-1 beta -511TT genotype or IL-1 beta*T-IL-1RN*1 (T1) haplotype had lower risk for middle third tumor location of EC in a northern Indian population.

The genetic predisposition to adverse outcome after trauma

Technological advances and shorter rescue times have allowed early and effective resuscitation after trauma and brought attention to the host response to injury. Trauma patients are at risk of progressive organ dysfunction from what appears to be an uncontrolled immune response. The availability of improved techniques of molecular diagnosis has allowed investigation of the role of genetic variations in the inflammatory response to post-traumatic complications and particularly to sepsis.

This review examines the current evidence for the genetic predisposition to adverse outcome after trauma. While there is evidence supporting the involvement of different polymorphic variants of genes in determining the post-traumatic course and the development of complications, larger-scale studies are needed to improve the understanding of how genetic variability influences the responses to post-traumatic complications and pharmacotherapy.

Interleukin (IL)-12 receptor beta1 codon 378 G homozygote and allele, but not IL-1 (beta-511 promoter, 3953 exon 5, receptor antagonist), IL-2 114, IL-4-590 intron 3, IL-8 3'-UTR 2767, and IL-18 105, are associated with higher susceptibility to leiomyoma

OBJECTIVE

To investigate whether certain polymorphisms are correlated with leiomyoma susceptibility, i.e., interleukin (IL)-1, IL-2, IL-4, IL-8, IL-12, and IL-18, which are all immunomodulatory cytokines that play important roles in host immune responses against cancers.

SETTING

Departments of gynecology and genetics in a medical center.

PATIENT(S)

Women were divided into: [1] a leiomyoma group (n = 162) and [2] a nonleiomyoma group (n = 156).

INTERVENTION(S)

Genotyping for the IL-1beta-511 promoter, IL-1beta exon 5, IL-1Ra, IL-2 114, IL-4 -590 intron 3, IL-8 3'-UTR 2767, IL-12Rbeta1 codon 378, and IL-18 105 were evaluated by polymerase chain reaction-restriction fragment length polymorphism.

MAIN OUTCOME MEASUREMENT(S)

Genotypes and allelic frequencies in both groups were compared.

RESULT(S)

Proportions of IL-12Rbeta1 codon 378 *CC/CG/GG in the leiomyoma and nonleiomyoma groups were: [1] 7.4%/43.8%/48.8% and [2] 11.5%/54.5%/34%, respectively. Distributions of other polymorphisms in both groups were not significantly different. Proportions of IL-1beta-511 promoter *CC/CT/TT were: [1] 22.8%/50%/27.2% and [2] 21.8%/57.1%/21.1% in the leiomyoma and nonleiomyoma groups, respectively. The IL-1beta exon 5 *E1 homozygote/heterozygote/E2 homozygote were: [1] 96.3%/3.7%/0% and [2] 96.9%/3.1%/0% in the leiomyoma and nonleiomyoma groups, respectively. Alleles I/II/III/IV/V for IL-1Ra were: [1] 92.6%/7.1%/0.3%/0/0% and [2] 93.9%/5.7%/0%/0.4/0% in the leiomyoma and nonleiomyoma groups, respectively. The IL-2 114 G homozygote/heterozygote/T homozygote were: [1] 27.8%/49.4%/22.8% and [2] 20.5%/53.2%/26.3% in the leiomyoma and nonleiomyoma groups, respectively. The IL-4 -590 intron 3 *RP1 homozygote/heterozygote/RP2 homozygote were: [1] 64.8%/32.7%/2.5% and [2] 69.2%/26.9%/3.9% in the leiomyoma and nonleiomyoma groups, respectively. The IL-8 3'-UTR 2767 A homozygote/heterozygote/G homozygote were: [1] 14.2%/43.8%/42% and [2] 20.5%/41.7%/37.8% in the leiomyoma and nonleiomyoma groups, respectively. The IL-18 *AA/AC/CC were: [1] 56.8%/40.7%/2.5% and [2] 59%/39.7%/1.3% in the leiomyoma and nonleiomyoma groups, respectively.

CONCLUSION(S)

The IL-12Rbeta1 codon 378 *G homozygote and G allele are related to a higher susceptibility to leiomyoma. The IL-1beta-511 promoter, IL-1beta exon 5, and IL-1Ra, IL-2 114, IL-4 -590 intron 3, IL-8 3'-UTR 2767, and IL-18 105 gene polymorphisms are not correlated with the development of leiomyoma.

Association of interleukin-1 receptor antagonist gene polymorphism and susceptibility to human brucellosis

The aim of this study was to determine the influence of the polymorphism within the intron 2 of the interleukin-1 receptor antagonist gene (IL-1Ra) on the susceptibility to or development of brucellosis. A total of 255 patients with brucellosis and 162 healthy volunteers were genotyped for polymorphisms in intron 2 of the IL-1Ra gene. The frequency of allele 2 of the IL-1Ra gene was significantly higher in patients with brucellosis compared with the controls (24.5% vs 18.5%, P = 0.03). Although the heterozygosity was more prevalent in patients than in control individuals, it did not have any statistical significance (P = 0.1). Alleles 3, 4, and 5 were absent in our study population. This work is the first that verifies a significant association between genetic polymorphism of IL-1Ra and susceptibility to brucellosis.

Is IL-1 a good therapeutic target in the treatment of arthritis?

Inflammation is an important homeostatic mechanism that limits the effects of infectious agents. However, inflammation might be self-damaging and therefore has to be tightly controlled or even abolished by the organism. Interleukin 1 (IL-1) is a crucial mediator of the inflammatory response, playing an important part in the body's natural responses and the development of pathological conditions leading to chronic inflammation. While IL-1 production may be decreased or its effects limited by so-called anti-inflammatory cytokines, in vitro IL-1 inflammatory effects are inhibited and can be abolished by one particularly powerful inhibitor, IL-1 receptor antagonist (IL-1Ra). Recent research has shown that in the processes of rheumatoid arthritis (RA) IL-1 is one of the pivotal cytokines in initiating disease, and IL-1Ra has been shown conclusively to block its effects. In laboratory and animal studies the inhibition of IL-1 by either antibodies to IL-1 or IL-1Ra proved beneficial to the outcome. Because of its beneficial effects in many animal disease models, IL-1Ra has been used as a therapeutic agent in human patients. The recombinant form of IL-1Ra, anakinra (Kineret, Amgen) failed to show beneficial effects in septic shock and displays weak effects in RA patients. However, IL-1 blockade by anakinra is dramatically effective in systemic-onset juvenile idiopathic arthritis, in adult Still's disease and in several autoinflammatory disorders, most of the latter being caused by mutations of proteins controlling IL-1beta secretion. Importantly, to be efficacious, anakinra required daily injections, suggesting that administered IL-1Ra displays very short-term effects. Better IL-1 antagonists are in the process of being developed.

Genetic association of interleukin-1β and receptor antagonist (IL-1Ra) gene polymorphism with allograft function in renal transplant patients

Cytokines are known to be important mediators during renal graft outcome. The present study was therefore, conducted to determine the impact of IL-1beta and its receptor antagonist polymorphism on allograft outcome. We evaluated single nucleotide polymorphism (SNPs) in interleukin-1 gene cluster, IL-1beta (promoter region -511 and exon-5 +3954) and IL-1Ra (86-bp VNTR) in 136 renal transplant recipients and 150 normal healthy controls by polymerase chain restriction based (PCR-RFLP) analysis. Recipients were HLA matched and clinically characterized including delayed graft function (DGF), rejection episode (RE) and stable graft function (SGF). Haplotypes and linkage disequilibrium (LD) were determined using SNPAnalyzer software. Significant difference was observed for the frequency distribution of the three sites of IL-1 gene among patients and controls (p<0.001, 0.022 and <0.001 respectively). When RE and DGF were compared to SGF, only IL-1Ra showed significant differences among RE and SGF (p=0.014) and DGF and SGF (p=0.020). The presence of 1/2 genotype showed 18 folds risk in RE and 10 folds in DGF (OR=18.000 and OR=10.667 respectively). The majority of recipients with SGF had 1-4 HLA mismatch whereas RE had 5-8 mismatches. Risk for rejection increased >6 folds (OR=6.571; p<0.01) for 5-8 mismatches. Haplotypes constructed with the combination of three polymorphisms in IL-1 gene cluster showed significant difference between RE and SGF group. LD value for IL-1beta (promoter region) and IL-1Ra and IL-1beta promoter and exon-5 gene in the control group indicated strong association among the variants (D'=0.37, p<0.0001 and D'=0.29, p=0.002). Our study demonstrate that genetically determined low production of IL-1Ra may be a risk factor for RE and DGF and that IL-1beta/IL-1Ra haplotype influences the impact of allograft outcome. These findings may significantly abet in better perception of the survival of the graft.

-511 C/T IL1B gene polymorphism is associated to resistance to bisphosphonates treatment in Paget disease of bone

INTRODUCTION

Osteoclasts are the most important cells involved in the pathogenesis of Paget disease of bone (PDB). Cytokines stimulate osteoclast differentiation and activation, with some of them over-expressed in pagetic osteoclasts. We have assessed whether genetic variability in genes coding of proteins from the IL1 pathway clustered in chromosome 2 is associated with clinical characteristics and the therapeutic response of patients with PDB.

METHODS

We have studied -511 C/T and +3953 T/C polymorphisms of the IL1B gene, a HinfI polymorphism in the 5'UTR of the IL1R1 gene, and a variable number of tandem repeats (VNTR) in the intron 2 of the IL1RN gene, in 165 patients diagnosed as suffering from PDB and in 122 healthy controls. Distribution of genotypes and alleles was studied for association with clinical and laboratory data and response to bisphosphonate (BSP) treatment.

RESULTS

No differences were observed in the distribution of genotypes or alleles between PDB patients and control subjects. We also failed to detect differences concerning epidemiological, clinical and laboratory data in the series of PDB patients. However, the -511 CC genotype of the IL1B gene was associated with a higher percentage of resistance to BSP (49% vs. 20%; P = 0.00 for all BSP, 60% vs. 39%, P = 0.17 for etidronate, 50% vs. 37% P = 0.53 for clodronate, 48 vs. 34% P = 0.05 for tiludronate and 50% vs. 4% P = 0.01 for risedronate).

CONCLUSIONS

Our results suggest that the -511 CC genotype of the IL1B gene could be related to resistance to bisphosphonates in patients with PDB.

A polymorphism of the interleukin 1 receptor antagonist is not associated with polycystic ovary syndrome in Caucasian women

In a prospective case-control study we investigated the association of a common polymorphism of the interleukin 1 receptor antagonist gene (IL-1 RA) with the occurrence and the clinical characteristics of polycystic ovary syndrome (PCOS). Allele frequencies did not vary statistically significantly among women with PCOS and healthy controls or within the PCOS group with respect to their clinical characteristics.

Lack of association between the IL1A gene (-889) polymorphism and outcome after head injury

BACKGROUND

Interleukin (IL) 1 is a proinflammatory cytokine that has been identified as an important mediator of neurodegeneration induced by ischemia or traumatic brain injury. Accumulating evidence to date has suggested that the major cytokine contributing to neurodegeneration after head injury is IL-1beta rather than IL-1alpha; however, there is no sufficient data regarding IL-1alpha in literature, and there may be an association between IL1A gene polymorphism and outcome after head injury.

METHODS

We performed a prospective clinical study and included a recruited series of 71 patients who had head injury and were admitted to our neurosurgical unit. Severity of initial injury was assessed by the Glasgow Coma Scale. Outcome at 6 months after injury was assessed by means of the Glasgow Outcome Score. Interleukin 1alpha genotypes were determined from blood samples by standard methods.

RESULTS

Of 40 patients with IL1A*2, 18 (45%) had an unfavorable outcome (dead, vegetative state, or severe disability) compared with 7 (22.5%) of 31 without IL1A*2 (P = .08).

CONCLUSION

Our findings show that there is no genetic association between IL1A gene polymorphism and outcome after head injury. Further clinical studies should be designed to confirm and further evaluate these findings.

Relations between interleukin-1, its receptor antagonist gene polymorphism, and bone mineral density in postmenopausal Korean women

We investigated the relation between polymorphisms in the interleukin-1(IL-1) and IL-1 receptor antagonist (IL-1ra) gene, and bone mineral density (BMD) in postmenopausal Korean women. The IL-1alpha C(-889)T polymorphism, and IL-1beta C(-511)T polymorphism were examined by restriction fragment length polymorphism, and 86-bp variable number tandem repeat polymorphism in the IL-1ra gene was analyzed by the polymerase chain reaction and electrophoresis in 202 postmenopausal Korean women. Serum osteocalcin, and C-telopeptide of type I collagen were measured using a radioimmunoassay and enzyme-linked immunosorbent assay, respectively. BMD at the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometer. No significant differences in BMD or in serum bone markers levels were noted across the IL-1alpha or IL-1beta genotype. There were no significant differences in the distribution of IL-1alpha or IL-1beta genotype according to the status of bone mass. BMD in women carrying the A2 allele of the IL-1ra gene was significantly lower than those without this allele, and the A2 allele was more frequent in osteoporotic women than in normal women. These data suggest that IL-1ra gene VNTR polymorphism is a genetic factor that may affect BMD in Korean women.

The role of IL-1 and IL-1Ra in joint inflammation and cartilage degradation

Interleukin (IL)-1 is a cytokine that plays a major role in inflammatory responses in the context of infections and immune-mediated diseases. IL-1 refers to two different cytokines, termed IL-1alpha and IL-1beta, produced from two genes. IL-1alpha and IL-1beta are produced by different cell types following stimulation by bacterial products, cytokines, and immune complexes. Monocytes/macrophages are the primary source of IL-1beta. Both cytokines do not possess leader peptide sequences and do not follow a classical secretory pathway. IL-1alpha is mainly cell associated, whereas IL-1beta can be released from activated cells after cleavage of its amino-terminal region by caspase-1. IL-1 is present in the synovial tissue and fluids of patients with rheumatoid arthritis. Several in vitro studies have shown that IL-1 stimulates the production of mediators such as prostaglandin E(2), nitric oxide, cytokines, chemokines, and adhesion molecules that are involved in articular inflammation. Furthermore, IL-1 stimulates the synthesis and activity of matrix metalloproteinases and other enzymes involved in cartilage destruction in rheumatoid arthritis and osteoarthritis. The effects of IL-1 are inhibited in vitro and in vivo by natural inhibitors such as IL-1 receptor antagonist and soluble receptors. IL-1 receptor antagonist belongs to the IL-1 family of cytokines and binds to IL-1 receptors but does not induce any intracellular response. IL-1 receptor antagonist inhibits the effect of IL-1 by blocking its interaction with cell surface receptors. The use of IL-1 inhibitors in experimental models of inflammatory arthritis and osteoarthritis has provided a strong support for the role of IL-1 in the pathogeny of these diseases. Most importantly, these findings have been confirmed in clinical trials in patients with rheumatic diseases. Additional strategies aimed to block the effect of IL-1 are tested in clinical trials.

Unusual linkage patterns of ligands and their cognate receptors indicate a novel reason for non-random gene order in the human genome

BACKGROUND

Prior to the sequencing of the human genome it was typically assumed that, tandem duplication aside, gene order is for the most part random. Numerous observers, however, highlighted instances in which a ligand was linked to one of its cognate receptors, with some authors suggesting that this may be a general and/or functionally important pattern, possibly associated with recombination modification between epistatically interacting loci. Here we ask whether ligands are more closely linked to their receptors than expected by chance.

RESULTS

We find no evidence that ligands are linked to their receptors more closely than expected by chance. However, in the human genome there are approximately twice as many co-occurrences of ligand and receptor on the same human chromosome as expected by chance. Although a weak effect, the latter might be consistent with a past history of block duplication. Successful duplication of some ligands, we hypothesise, is more likely if the cognate receptor is duplicated at the same time, so ensuring appropriate titres of the two products.

CONCLUSION

While there is an excess of ligands and their receptors on the same human chromosome, this cannot be accounted for by classical models of non-random gene order, as the linkage of ligands/receptors is no closer than expected by chance. Alternative hypotheses for non-random gene order are hence worth considering.

A candidate gene approach of immune mediators effecting the susceptibility to and severity of upper gastrointestinal tract diseases in relation to Helicobacter pylori and Epstein-Barr virus infections

This review focuses on immunogenetic aspects of diseases of the upper gastrointestinal tract in which infectious agents may play a role in the aetiopathogenesis, such as Helicobacter pylori, Epstein-Barr virus (EBV) and HIV. Gastric adenocarcinoma is a common cancer all around the world, with declining incidences in Europe and high incidences in Asia and central and south America. Together with gastric atrophy and peptic ulcer disease, gastric adenocarcinoma belongs to the commonest upper gastrointestinal tract diseases. These diseases are multifactorial and factors such as smoking and dietary habits contribute to the pathogenesis. More recently, scientists have turned their eyes on the host. Functional polymorphisms in the genes regulating the host immune system may contribute to the susceptibility to and progression of disease. In multifactorial and polygenetic diseases, candidate gene studies of single nucleotide polymorphisms (SNPs) detect small to moderate relative risks. Unfortunately, only a few functional SNPs have been identified. The candidate gene approach can be seen as a useful first step in exploring causal pathways between genetic determinants and complex diseases such as those mentioned above. To date, little is known about the immunogenetics of upper gastrointestinal tract diseases. We review the literature on H. pylori, EBV and gene polymorphisms that affect key immune mediators influencing the pathogenesis of the inflammatory response, such as the genes that code for the IL-1 family, TNF-alpha, lymphotoxin alpha, and IL-10. IL-1, IL-10, lymphotoxin alpha and TNF-alpha polymorphisms increase the risk of upper gastrointestinal pathogenesis in H. pylori-infected patients, whereas IL-1 and TNF-alpha polymorphisms confer risk in EBV-infected patients.

Impact of a genetic polymorphism of the interleukin-1 receptor antagonist on technique survival in peritoneal dialysis patients

BACKGROUND/AIMS

There is a clear association between one allele of the interleukin-1 receptor-antagonist gene (IL-1RN) and inflammatory diseases in which IL-1 is implicated. We evaluated patient survival and technique survival of peritoneal dialysis (PD) patients, while analyzing independent risk factors, in a PD program. We also tested the association between IL-1RN polymorphism, patient survival and technique survival.

METHODS

We retrospectively evaluated 129 Japanese CAPD patients undergoing initial treatment in eight centers in Japan. Using PCR, IL-1RN genotype and allele frequencies were determined, and clinical and biochemical variables were recorded at the start of PD. The relation of patient survival or technique survival with IL-1RN polymorphism and those variables was analyzed with a multivariate Cox's proportional-hazard model.

RESULTS

The frequencies of IL-1RN*1/IL-1RN*1 and IL-1RN*1/IL-1RN*2 genotypes were 84.5 and 15.5%, respectively. Median patient survival was 37.0 months, and overall patient survival was 92.8 and 87.9% at 2 and 5 years, respectively. Age, cardiovascular disease and serum albumin were found to be independent predictors of patient survival. Median technique survival was 32 months. PD failure occurred in 37 patients, with technique survival rates of 92.0 and 72.7% at 2 and 5 years, respectively. Serum albumin, peritonitis and the presence of the IL-1RN*2 genotype were found to be independent predictors of technique survival.

CONCLUSION

Serum albumin was the strongest predictive factor for mortality and technique failure in PD. Technique failure was also affected by IL-1RN polymorphism in this patient population.

Interleukin-1 receptor antagonist haplotype associated with prostate cancer risk

IL1-RN is an important anti-inflammatory cytokine that modulate the inflammation response by binding to IL1 receptors, and as a consequence inhibits the action of proinflammatory cytokines IL1alpha and IL1beta. In this study, we hypothesise that sequence variants in the IL1-RN gene are associated with prostate cancer risk. The study population, a population-based case-control study in Sweden, consisted of 1383 prostate cancer case patients and 779 control subjects. We first selected 18 sequence variants covering the IL1-RN gene and genotyped these single-nucleotide polymorphisms (SNPs) in 96 control subjects. Gene-specific haplotypes of IL1-RN were constructed and four haplotype-tagging single-nucleotide polymorphisms (htSNPs) were identified (rs878972, rs315934, rs3087263 and rs315951) that could uniquely describe >95% of the haplotypes. All study subjects were genotyped for the four htSNPs. No significant difference in genotype frequencies between cases and controls were observed for any of the four SNPs based on a multiplicative genetic model. Overall there was no significant difference in haplotype frequencies between cases and controls; however, the prevalence of the most common haplotype (ATGC) was significantly higher among cases (38.7%) compared to controls (33.5%) (haplotype-specific P = 0.009). Evaluation of the prostate cancer risk associated with carrying the 'ATGC' haplotype revealed that homozygous carriers were at significantly increased risk (odds ratio (OR) = 1.6, 95% confidence interval (CI) = 1.2-2.2), compared to noncarriers, while no significant association was found among subjects heterozygous for the haplotype (OR = 1.0, 95% CI = 0.8-1.2). Restricting analyses to advanced prostate cancer strengthened the association between the 'ATGC' haplotype and disease risk (OR for homozygous carriers vs noncarriers 1.8, 95% CI = 1.3-2.5). In conclusion, the results from this study support the hypothesis that inflammation has a role of in the development of prostate cancer, but further studies are needed to identify the causal variants in this region and to elucidate the biological mechanism for this association.

Interleukin-4 gene, but not the interleukin-1 beta gene polymorphism, is associated with oral cancer

We aimed to evaluate whether polymorphisms of the interleukin-4 (IL-4) gene promoter and intron 3 regions, and polymorphisms of the IL-1 beta gene promoter and exon 5 regions are associated with oral cancer. This study included 130 patients with oral cancer and 105 age-matched healthy controls who lived in the same area as the patients. Each genetic polymorphism was typed by polymerase chain reaction (PCR)-based restriction analysis. We then compared the genotype distribution and allelic frequencies of each polymorphism between the oral cancer patients and the controls. The CC homozygote genotype of the IL-4 gene promoter -590 region differed significantly between the patients with oral cancer and the controls (odds ratio (OR)=6.0, 95% confidence interval (CI)=1.2-30.7, chi-square test, P=0.044). No significant difference in either the genotype distribution or the allelic frequencies of the IL-1 beta gene polymorphisms was observed between patients with oral cancer and controls. The IL-4 gene -590 C/T polymorphism is associated with oral cancer and is a suitable genetic marker for screening for oral cancer. However, whether the -590 C/T polymorphism of the IL4 gene plays a role in oral cancer remains unclear. Further substantiation based on larger patient samples is needed.

IL-1 receptor antagonist (IL-1Ra) gene polymorphism in patients with inflammatory bowel disease in India

OBJECTIVE

An association between polymorphism in the gene coding for the anti-inflammatory cytokine interleukin-1-receptor antagonist (IL-1Ra) and ulcerative colitis (UC) has been reported. To date, there is no report from India confirming this association. In the present study the aim was to assess the allele frequencies and carriage rates of different alleles of 86 bp (base pair) variable number tandem repeat (VNTR) in intron 2 of the IL-1Ra gene in patients with inflammatory bowel disease (IBD) and healthy controls from northern India.

MATERIAL AND METHODS

Eighty-two patients with UC, 21 with Crohn's disease (CD) and 141 ethnically matched controls were enrolled in this study. Genotyping was done using a polymerase chain reaction (PCR) amplification of the intron-2 fragment harboring a VNTR nucleotide sequence. The PCR products were separated on 2% agarose gel. Statistical analysis was performed using the chi-squared (chi(2)) test.

RESULTS

The frequencies of allele 2 in UC, CD and healthy controls were 26%, 50% and 24%, respectively. The frequency of allele 2 in CD was higher than that in UC (p = 0.002; OR = 2.9) and healthy controls (p = 0.001; OR = 3.1; 95% CI = 1.5-6.3). Alleles 3 and 4 were absent in patients with CD, while allele 5 was absent in all three groups.

CONCLUSIONS

The present study demonstrated an association between allele 2 and patients with CD but not with UC. Interestingly, the allele frequency and carriage rates of allele 2 were significantly higher in patients with CD than in patients with UC and in healthy subjects. Ethnic differences, genetic heterogeneity and sample size could be the reasons for such differences in comparison with studies from the West.

Genotypes and haplotypes in the IL-1 gene cluster: analysis of two genetically and diagnostically distinct groups of Alzheimer patients

Increased risk of Alzheimer's disease (AD) has been associated with polymorphisms in the IL-1 gene cluster, and in particular with the IL-1alpha-889 T/T genotype. However, this association is still unclear, and needs further investigation. In order to clarify the role of these polymorphisms in the complex pathogenesis of AD we examined genotype and haplotype frequencies of the two C-to-T SNPs at position -889 and -551 in the IL-1alpha and IL-1beta genes, respectively, and of the 86 bp VNTR intron-2 polymorphisms in the IL-1Ra gene. The analysis was performed in two genetically and diagnostically distinct groups of sporadic AD from Italy and the USA. In the Italian group a significant association between the IL-1alpha-889 T/T genotype and AD (OR=3.022, 95% CI: 1.001-9.119) was found, whereas no difference was found in the group from the USA. Results were also compared with previously published studies that analyzed the same IL-1 polymorphisms in AD. In both groups, the analysis of the estimated haplotypes shows that AD patients and controls who carry the IL-1beta-511 C allele, were also more frequently carriers of the IL-1Ra 1 allele (haplotypes -C-1). The total frequency of the two -C-1 haplotypes (C-C-1 plus T-C-1) was about one half of the total frequency of the eight estimated haplotypes. This was confirmed by significant linkage disequilibrium between these two loci in both the Italian and USA groups. In the Italian group a weak association of the T-C-2 haplotype with the disease (OR=1.648, 95% CI: 1.519-1.788) was also found, whereas in the USA group no difference was found. Although ours and other published data on different samples of Caucasian and non-Caucasian AD show a great heterogeneity in the frequencies of the IL-1alpha-889, the IL-1beta-511 and the IL-1Ra VNTR gene polymorphisms, we confirm the role of the IL-1alpha-889 T/T genotype as a risk factor for sporadic AD, and show the presence of an allelic association between IL-1beta C and IL-1Ra 1 alleles in both the Italian and the USA groups, confirmed by the presence of significant levels of linkage disequilibrium between these two loci.

INTERLEUKIN-1 GENE CLUSTER POLYMORPHISMS AND ALCOHOLISM IN SPANISH MEN

AIMS

In an attempt to explain differences in susceptibility to alcoholism and alcohol liver disease (ALD), different genes have been analysed, among them those encoding inflammatory cytokines. Thus, it has been reported recently that both the interleukin 1 receptor antagonist (IL1RN) and the IL1beta (IL1B) genes may influence the risk of ALD in Japanese alcoholics. We analysed the distribution of single nucleotide polymorphisms (SNPs) located in the IL1A, IL1B, IL1R1 and IL1RN genes in alcoholic and non-alcoholic Spanish subjects.

METHODS

DNA samples were obtained from 139 male alcoholics, 78 of whom were diagnosed as alcohol dependent (32 patients with liver cirrhosis and 46 without ALD) and 61 as alcohol abusers (25 with liver cirrhosis and 36 without ALD). As a control, we studied 81 age- and sex-matched healthy volunteers.

RESULTS

Alleles -511 IL1B*1 and IL1RN*1 were represented more in alcoholic patients than in the control group. We did not find any association of alcoholism or ALD with polymorphisms in the IL1A and IL1R1 genes.

CONCLUSIONS

We conclude that the proteins encoded by the IL1RN and IL1B genes may be involved in susceptibility to alcoholism in Spanish men, probably through a different pathway from that involved in the regulation of the inflammatory response.

Interleukin-1 beta gene polymorphism related with allergic pathogenesis in Iris constitution

Iridological constitution has a strong familial aggregation and is implicated in heredity. The aetiology of inflammatory bowel disease is still unknown. However, from genetic epidemiological studies there is considerable evidence that genetic factors are associated with both Crohn's disease and ulcerative colitis. We investigated the relationships between Iridological constitution and interleukin 1 beta (IL-1beta) gene polymorphism. IL-1beta is a major proinflammatiry cytokine, and the polymorphisms of this gene have been shown to be of importance in a number of diseases. Especially, IL-1 has been suspected of involvement in allergic pathogenesis. Also, IL-1beta genotype is one of the genetic markers of gastric cancer. Therefore, we classified 166 individuals according to Iris constitution, and determined IL-1beta genotype. The frequencies of Iris constitutions as follows: neurogenic type, 41 (24.7%); abdominal connective tissue weakness type, 53 (31.9%); cardio-renal connective tissue weakness type, 50 (30.1%); the others type, 22 (13.3%). Especially, the frequency of abdominal connective tissue weakness type was higher in C/T genotype than in the remaining constitutions although the statistical power was very weak. Furthermore, we first attempted to explore possible involvement of the IL-1beta polymorphism and the Iris constitution.

Association between the interleukin-1beta C(-511)T polymorphism and blood pressure in a Chinese hypertensive population

The interleukin-1beta (IL-1beta) is an important pro-inflammatory cytokine in a broad spectrum of physiological processes. Previous investigations have observed that levels of the IL-1beta were higher in essential hypertensive patients and the IL-1beta gene polymorphism has been shown to be related to IL-1 production. We hypothesized that genetically determined differences in activity or responsiveness of cytokine(s) might contribute to hypertension. In this report, we utilized a family-based design to test the association between the IL-1beta C(-511)T polymorphism and blood pressure levels in hypertensive patients chosen from rural communities in Anhui, China. In men, carriers of the IL-1beta (-511)*C allele were found to have lower systolic (P = 0.049) blood pressure levels compared with T homozygotes, which conforms to an additive effect model. By contrast, no significant association between the IL-1beta gene and blood pressure levels was revealed in women. Our results suggested a significant role of the IL-1beta C(-511)T polymorphism in the control of blood pressure in Chinese hypertensives.

Body mass index but not a polymorphism of the interleukin-1 receptor antagonist (IL-1 RA) gene is associated with age at natural menopause

BACKGROUND

A genetic component of the onset of menopause has been described and several candidate genes have been identified. We hypothesized that carriage of a polymorphism of the interleukin-1 receptor antagonist gene (IL-1 RA) is associated with an early age at menopause.

METHODS

In a prospective cohort study, 90 consecutive postmenopausal Caucasian women were genotyped by PCR for the presence of an 86-base pair tandem repeat polymorphism in intron 2 of IL-1 RA.

RESULTS

We found that 36/90 (40%) women were homozygous for the wild-type allele 1 and 49/90 (54%) women were heterozygous for any of the variant alleles (1/2 [n = 44], 1/3 [n = 3], 2/3 [n = 2]). Two women (2%) were homozygous carriers of the variant allele 2. The wild-type allele 1 was identified on 119 of 180 chromosomes for an allele frequency of 0.66. The polymorphic alleles 2 and 3 were present on 56 and 5 chromosomes, respectively (allele frequencies 0.31 and 0.03, respectively). No correlation between the IL-1 RA genotype and the age at menarche and menopause, the length of the reproductive period, and the number of deliveries and miscarriages was ascertained. As to allele frequencies, homozygous and heterozygous carriers of the variant allele 2 had a median age at menopause of 50 (range 40-48) years, compared to 49.5 (range 39-56) years for women with no allele 2 (p value 0.41). Women with at least one allele 2 had a median age at menarche of 13 (range 10-16) years, compared to 13 (range 10-17) years for women with no allele 2 (p value 0.1). Decreasing body mass index, but not smoking, was correlated with an increasing age at natural menopause (r = -0.23, p = 0.04).

CONCLUSIONS

Our preliminary data suggest that an 86-base pair tandem repeat polymorphism in intron 2 of IL-1 RA does not modulate the onset and cessation of menses in this cohort of Caucasian women.

Interleukin-10 gene -627 allele variants, not interleukin-I beta gene and receptor antagonist gene polymorphisms, are associated with atopic bronchial asthma

Asthma is an airway hyperresponsive disease characterized by the expression of multiple inflammatory genes, including cytokines. Interleukin-I and interleukin-10 (IL-1 and IL-10) are cytokines that might play a role in the process of inflammation and are therefore considered to be involved in the pathogenesis of bronchial asthma. The aim of this study was to test whether the polymorphisms of the promoter region and exon 5 of the IL-1 gene, intron 2 of the IL-1Ra gene, and -627 nucleotide (C/A) of the IL-10 gene could be genetic markers for the susceptibility of bronchial asthma. A normal control group made up of 47 healthy volunteers and 117 patients with bronchial asthma were examined in this study. We analyzed the variable number of tandem repeats at intron 2 of the IL-1Ra gene for the polymorphisms by polymerase chain reaction (PCR). PCR-based restriction analysis of the IL-1 gene polymorphisms of the promoter region and exon 5 was carried out by the endonucleases Ava I and Taq I, respectively. The IL-10 gene -627 C/A polymorphisms were investigated by PCR-based restriction analysis. The distribution of CC homozygotes in the IL-10 gene was significantly lower in asthma patients than in controls (P=0.013, OR=3.599, 95% CI=1.240 approximately 10.441). The polymorphisms studied in the IL-1 genes did not reveal any significant association with bronchial asthma when compared with the control group (promoter region by chi-square test, P=0.627; exon 5 region by Fisher's exact test, P=0.403). Only two alleles of the IL-1Ra gene corresponding to one and two copies of an 86-base pair sequence repeat were identified by PCR in the control group. There were three alleles found in the asthmatic patient group. The results revealed no significant differences between normal individuals and asthma patients (P=0.454, Fisher's exact test). The IL-10 gene -627 "A" allele is an associated risk factor of developing atopic asthma.

High-throughput single-nucleotide polymorphism analysis of the IL1RN locus in patients with ankylosing spondylitis by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry

OBJECTIVE

To examine single-nucleotide polymorphisms (SNPs) in the 3' region of the IL1RN gene in a large Caucasoid case-control series and in ankylosing spondylitis (AS) families from Western Canada by use of high-throughput MassArray matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry SNP typing.

METHODS

An association analysis was performed in a case-control cohort of 394 AS cases and 500 controls. Family-based association analysis was performed in 58 simplex and 13 multiplex families. Three SNPs located in the 3' region of the IL1RN gene (T/C at position 27810 in exon 4, T/C at position 30735 in exon 6, and G/C at position 31017 in exon 6) were examined by high-throughput MassArray MALDI-TOF mass spectrometry. Haplotype inference software programs were used to infer the most likely haplotypes and to compare haplotype frequencies, which were then further analyzed in family-based association studies by transmission disequilibrium tests.

RESULTS

The frequency of allele C at SNP position 30735 in exon 6 was significantly increased in AS cases (35.1%) versus controls (27.8%), as was the phenotype frequency (61.7% versus 48.6%). A significantly increased frequency of SNP allele G at position 31017 in exon 6 in cases (32.9%) versus controls (28.3%) was also noted. A highly significant difference in the overall distribution of haplotype frequencies was evident between cases and controls, with significant increases in the frequencies of the 27810C/30735C/31017C and 27810C/30735T/31017G haplotypes, but a significant reduction in the estimated frequency of the 27810C/30735T/31017C haplotype, in the AS cases. Estimation of haplotype frequencies based on 2 SNP markers indicated a highly significant increase in the 30735C/31017C haplotype and a highly significant decrease in the 30735T/31017C haplotype in cases compared with controls. Preliminary evidence for reduced transmission of the 27810C/30735T/31017C 3-marker haplotype was also found in family-based association analyses.

CONCLUSION

Our data establish a highly significant disease association with markers in the IL1RN gene. In the absence of nonsynonymous coding sequence substitutions, it is possible that the primary disease-associated locus regulates gene expression. Association with specific haplotypes raises the possibility that the primary disease locus is in linkage disequilibrium with a specific combination(s) of markers in the IL1RN gene.

Lack of association between the interleukin-1alpha gene C(-889)T polymorphism and Alzheimer's disease in a Chinese population

Interleukin 1A (IL-1A), a potent proinflammatory cytokine, has been implicated in the pathogenesis of Alzheimer's disease (AD). Several recent studies have shown that a polymorphism in the IL-1A locus -889 was associated with AD risk and onset age, however, other studies were not able to replicate these findings. In this investigation, the IL-1A C(-889)T polymorphism has been analyzed for a Chinese population of 234 AD patients and 170 controls. There were no significance differences in IL-1A genotype or allele frequencies comparing the AD cases and controls, even after stratification for age of onset and adjustment for apolipoprotein E genotype. The results reveal that it is not likely that the IL-1A C(-889)T polymorphism is involved in AD pathogenesis in the Chinese population. Further studies of the associations between other IL-1A genetic polymorphisms and AD are needed to fully elaborate the involvement of this gene in AD.

Interleukin-1beta gene polymorphism in women with vulvar vestibulitis syndrome

OBJECTIVE

The pathogenesis of vulvar vestibulitis syndrome remains unknown but may be related to a localized chronic inflammation. The relation between this syndrome and a polymorphism at position +3953 in the interleukin-1beta gene was examined. Allele 2 of this gene has been associated with increased pro-inflammatory immunity.

STUDY DESIGN

Buccal or vestibular swabs from 59 women with strictly defined vulvar vestibulitis and from 48 healthy women were tested by polymerase chain reaction for the presence of two alleles at the +3953 interleukin-1beta locus.

RESULTS

Allele 2 of the interleukin-1beta gene was identified in 27 (46%) women with vulvar vestibulitis as opposed to 12 (25%) control women (P=0.03). The interleukin-1beta 1,1 genotype was present in 36 (75%) controls as opposed to 32 (54%) vulvar vestibulitis syndrome patients (P=0.02). All subjects had been previously tested for induced interleukin-1beta production in response to bacterial lipopolysaccharide. In both patients and controls, possession of allele 2 was associated with a small but non-statistically significant increase in induced interleukin-1beta production.

CONCLUSION

Allele 2 in the interleukin-1beta gene is more common in women with vulvar vestibulitis syndrome than in other women. Susceptibility to vulvar vestibulitis syndrome might be influenced by carriage of this polymorphism.

Interleukin-1beta and interleukin-1 receptor antagonist gene polymorphism in postmenopausal women: correlation to bone mineral density and susceptibility to osteoporosis

OBJECTIVE

Osteoporosis is a common disorder with a strong genetic component. Our aim was to investigate the correlations of the interleukin-1beta (IL-1beta) and interleukin-1 receptor antagonist (IL-1Ra) gene polymorphisms with bone mineral density (BMD) and their relationship to osteoporosis.

METHODS

The IL-1beta (promoter and exon 5) and IL-1Ra (intron 2) gene polymorphisms were determined using polymerase chain reaction. BMD of the lumbar spine and proximal femur were measured using dual-energy X-ray absorptiometry.

RESULTS

The prevalence of each genotype of the interleukin-1 related genes in the study population was: (1) 14% C/C, 71.5% C/T, and 14.5% T/T in IL-1beta promoter; (2) 95.3% E1/E1 and 4.7% E1/E2 in IL-1beta exon 5; (3) 92.4% I/I, 6.4% I/II, and 1.2% II/II in IL-1Ra intron 2. After adjustment for potential confounding factors such as age, height, weight, years since menopause, and daily calcium intake, subjects with genotype E1/E2 (n=8) in IL-1beta exon 5 had lower BMD values and a significantly greater risk for osteoporosis (OR 10.6, 95% CI 1.3-83.8) at the lumbar spine when compared with subjects with genotype E1/E1 (n=164) in IL-1beta exon 5.

CONCLUSION

The Taq I IL-1beta exon 5 gene polymorphism is associated with reduced BMD and predisposes women to osteoporosis at the lumbar spine, but our results should be interpreted with caution because of the small number of subjects with the unfavorable E1/E2 genotype.

Interleukin-1 receptor antagonist gene polymorphism, vaginal interleukin-1 receptor antagonist concentrations, and vaginal ureaplasma urealyticum colonization in pregnant women

Ureaplasma urealyticum is the microorganism most frequently isolated from amniotic fluids of women in preterm labor. The relationship between vaginal colonization with U. urealyticum, vaginal interleukin-1 receptor antagonist (IL-1ra) levels, and the IL-1ra genotype in pregnant women was examined. Vaginal specimens, obtained with a cotton swab from 207 women in their first trimester of pregnancy, were tested for IL-1ra concentrations by enzyme-linked immunosorbent assay and for U. urealyticum and IL-1ra genotypes by PCR. U. urealyticum was detected in 85 (41.1%) women. The median IL-1ra level was 450 ng/ml in women positive for U. urealyticum, as opposed to 225 ng/ml in women negative for this microorganism (P < 0.0001). Sixty-two percent of the 16 women who were homozygous for allele 2 of the IL-1ra gene (IL-1RN*2) were colonized with U. urealyticum, as opposed to 47% of the 49 women who were IL-1RN*1/IL-1RN*2 heterozygotes and 34% of the 133 women who were IL-1RN*1 homozygotes (P < 0.05). Median IL-1ra levels were 750 ng/ml in IL-1RN*2 homozygotes, 300 ng/ml in IL-1RN*1/IL-1RN*2 heterozygotes, and 250 ng/ml in IL-1RN*1 homozygotes (P = 0.02). The vast majority of subjects had an uneventful pregnancy and delivered a healthy infant at term. The IL-1ra genotype or U. urealyticum colonization was unrelated to birth weight. Pregnant women who are colonized with U. urealyticum during the first trimester have elevated vaginal IL-1ra concentrations and a higher prevalence of the IL-1RN*2 homozygote genotype than do noncolonized women.

Polymorphisms in interleukin-1beta and interleukin-1 receptor antagonist genes and malaria in Ghanaian children

We have investigated the possible associations between polymorphisms in two interleukin-1 (IL-1) genes and severity of Plasmodium falciparum malaria in Ghanaian children with cerebral malaria, severe anaemia or uncomplicated malaria and controls. There was no significant difference in genotype and allele frequencies in IL-1beta exon 5 or interleukin-1 receptor antagonist (IL-1ra) polymorphisms between the studied groups, suggesting that the two polymorphisms may not be involved in the pathogenesis of severe malaria. When parasitaemias in uncomplicated malaria patients were evaluated, a significantly higher level of parasitaemia was observed among carriers of IL-1beta A2 allele as compared with noncarriers of this allele (P = 0.01). The mean parasitaemia in an age-matched asymptomatic group did not reveal such associations. These data suggest that IL-1beta exon 5 allele 2 may play a possible role in the clinical outcome of uncomplicated malaria.

Interleukin-1 receptor antagonist VNTR-polymorphism in inflammatory bowel disease

Both genetic and environmental factors have been implicated in the etiology of inflammatory bowel diseases (IBD) i.e., Crohn's disease (CD) and ulcerative colitis (UC). Polymorphisms in cytokine genes are likely to influence an individual's predisposition to IBD. In intron 2 of the interleukin-1 receptor antagonist (IL-1ra) gene, a variable number of an 86-bp tandem repeat (VNTR) polymorphism leads to the existence of five different alleles. In order to analyze the association between certain IL-1ra VNTR-alleles and IBD, we investigated the IL-1ra genotype and allele frequencies in 342 unrelated IBD patients and in 401 healthy control individuals. CD patients were also genotyped for the three main associated variants in the NOD2/CARD15 gene. In the IBD group, a significant decrease in the frequency of IL-1ra allele 1 (P=0.048) compared to controls was observed. The frequency of IL-1ra genotype 1/1 was significantly lower in the IBD population vs the control group (P=0.018). Analysis of the CD population without NOD2 homozygotes and compound heterozygotes revealed a more significant decrease in IL-1ra genotype 1/1 compared to controls (P=0.038). These results support the hypothesis that the IL-1ra VNTR-polymorphism could be among the genetic factors that are of importance in IBD susceptibility.

The balance between IL-1 and IL-1Ra in disease

IL-1 is an important mediator of inflammation and tissue damage in multiple organs, both in experimental animal models of disease and in human diseases. The IL-1 family consists of two agonists, IL-1alpha and IL-1beta, two receptors, biologically active IL-1RI and inert IL-1RII, and a specific receptor antagonist, IL-1Ra. The balance between IL-1 and IL-1Ra in local tissues plays an important role in the susceptibility to and severity of many diseases. An allelic polymorphism in the IL-1Ra gene has been associated with a variety of human diseases primarily of epithelial and endothelial cell origin. This association may be secondary to an imbalance in the IL-1 system with enhanced production of IL-1beta and reduced production of the major intracellular isoform of IL-1Ra. Treatment of RA with daily subcutaneous injections of recombinant IL-1Ra protein has been shown to be efficacious. Gene therapy approaches with IL-1Ra are being evaluated for the treatment of RA and other human diseases.

Linkage and association studies of IL1B and IL1RN gene polymorphisms in preeclampsia

OBJECTIVE

To determine whether preeclampsia is either associated with or linked to two polymorphisms in the IL1B gene (IL1B-TaqI and IL1B-511) and one polymorphism in the IL1RN gene (IL1RN-IVS2).

METHODS

Genotyping was performed in 150 affected sib-pair families and 104 healthy Dutch blood donors. Genotype and allele frequencies as well as allelic associations were assessed in three groups of unrelated women from these 150 families; 133 with either eclampsia, preeclampsia or the haemolysis, elevated liver enzymes, low platelets (HELLP) syndrome, 101 with preeclampsia only, and 63 with HELLP syndrome only. These frequencies were compared to those in controls. Frequencies of transmitted and nontransmitted haplotypes, inferred from the three polymorphisms, were compared. Allele sharing between affected siblings from all 150 families was assessed by means of multipoint nonparametric affected sib-pair analyses.

RESULTS

No significant differences in genotype and allele frequencies were found between the unrelated study groups and controls. No allelic associations were apparent, nor were there differences in frequencies of transmitted and nontransmitted haplotypes within affected families. Excess allele sharing for any of the three polymorphic markers was absent in affected sib-pairs.

CONCLUSIONS

None of the IL1B and IL1RN polymorphisms provided evidence for either association or linkage with the risk for (pre)eclampsia/HELLP syndrome, preeclampsia only or HELLP syndrome only.

A sequence-based map of the nine genes of the human interleukin-1 cluster

Six novel genes encoding proteins with the interleukin (IL)-1 fold have been identified recently. The classical family members are involved in inflammatory signaling. Previous work has placed the novel genes close to or within the same cluster as IL1A, IL1B, and IL1RN, which occupy an approximately 400-kb interval on chromosome 2. We have combined the incomplete public database sequence with our own sequence to generate a reference sequence and map that encompass all of the novel genes, allowing determination of the gene structures, precise localization of exons, and determination of distances between conventional SNP and microsatellite markers. Gene order from centromere to telomere is IL1A-IL1B-IL1F7-IL1F9-IL1F6-IL1F8-IL1F5-IL1F10-IL1RN, of which only IL1A, IL1B, and IL1F8 are transcribed towards the centromere. The gene order relates to the evolutionary relationship between the genes. Key features of exon boundaries are conserved. There is no evidence for other IL-1 family members within the cluster.

Genetic risk factors for chronic obstructive pulmonary disease

Cigarette smoking is clearly the major risk factor for chronic obstructive pulmonary disease. However, only a minority of cigarette smokers develops chronic obstructive pulmonary disease, indicating that other factors are involved. Family and twin studies suggest that at least some of those factors are genetic. This article reviews the genes investigated as potential risk factors for this disease, focusing on the recent literature. The only established genetic risk factor for chronic obstructive pulmonary disease is homozygosity for the Z allele of the alpha1 -antitrypsin gene. There is increasing evidence that heterozygotes for the Z allele may also be at increased risk. Variants in genes involved in xenobiotic metabolism, antioxidation, and the inflammatory response have also been associated with chronic obstructive pulmonary disease. Thus, the genetic basis for chronic obstructive pulmonary disease has begun to be elucidated, and it is likely that several genes will be implicated in the pathogenesis of this disease.

Influence of interleukin-1 receptor antagonist gene polymorphism on disease

Interleukin-1 receptor antagonist (IL-1RA) is a naturally occurring competitive inhibitor of interleukin-1 (IL-1)-induced proinflammatory activity. The IL-1RA gene is polymorphic, resulting in quantitative differences in both IL-1RA and IL-1beta production. Persons homozygous for allele 2 of the IL-1RA gene (IL1RN*2) have a more prolonged and more severe proinflammatory immune response than persons with other IL-1RA genotypes. Thus, being IL1RN*2 homozygous might be beneficial when combating infectious agents or malignantly transformed cells, but it might be detrimental for those with chronic inflammatory conditions or who are pregnant. The IL1RN*2 phenotype is associated with ulcerative colitis and Crohn's disease, lupus erythematosus, vulvar vestibulitis, and possibly with osteoporosis and coronary artery disease. IL1RN*2 homozygosity may also be associated with recurrent spontaneous abortion, preterm birth, and severity of preeclampsia. Conversely, there are negative associations between IL1RN*2 homozygosity and vaginal colonization with mycoplasmas, infection with human cytomegalovirus and Epstein-Barr virus, human immunodeficiency virus proliferation, and the occurrence of ovarian cancer.

Association of IL-1beta and IL-1 receptor antagonist haplotypes with rate of decline in lung function in smokers

BACKGROUND

There is increasing evidence that the cytokine network is central to the immunopathology of inflammatory airway diseases. The interleukin 1 (IL-1) receptor antagonist (IL-1RN) is a naturally occurring anti-inflammatory agent that binds to the IL-1 receptor but does not possess agonist activity. Each of the genes of the IL-1 locus on chromosome 2q14 is polymorphic. The IL1RN gene contains an 86 bp tandem repeat and allele 2 of this polymorphism has been associated with various inflammatory diseases. The IL-1beta (IL1B) gene contains a promoter polymorphism (C-511T) that has been associated with inflammatory diseases and is in linkage disequilibrium with the IL1RN polymorphism.

METHODS

We investigated whether polymorphisms in the IL1B and IL1RN genes were associated with rate of decline of lung function. Genotypes were determined in 284 smokers with a rapid decline in lung function and 306 smokers with no decline in lung function.

RESULTS

None of the genotypes was associated with the rate of decline of lung function. However, the distribution of IL1B/IL1RN haplotypes was different between smokers with a rapid decline in lung function and those with no decline in lung function (p=0.0005).

CONCLUSION

These results suggest that IL1B/IL1RN haplotypes play a role in the rate of decline in lung function in smokers.

Cloning and characterization of IL-1HY2, a novel interleukin-1 family member

The interleukin-1 (IL-1) family members play an important role in the process of inflammation and host defense. We describe here the identification and characterization of a novel member of the IL-1 family, IL-1HY2. The human IL-1HY2 protein shares significant amino acid sequence similarity (37%) with the IL-1 receptor antagonist and has a predicted three-dimensional structure similar to that of the IL-1 receptor antagonist. The IL-1HY2 gene is located in close proximity to other IL-1 family genes on human chromosome 2, and the genomic organization of the IL-1HY2 gene is highly conserved with other IL-1 family members. IL-1HY2 protein is secreted from mammalian cells, and the purified recombinant IL-1HY2 protein binds soluble IL-1 receptor type I. IL-1HY2 is expressed in human skin, spleen, and tonsil. Immunohistochemical analysis showed that the IL-1HY2 protein is expressed in the basal epithelia of skin and in proliferating B cells of the tonsil. These data suggest that IL-1HY2 is a novel IL-1 family member and that it may participate in a network of IL-1 family members to regulate adapted and innate immune responses.

Interleukin 1 receptor antagonist polymorphism in women with idiopathic recurrent miscarriage

OBJECTIVE

Proinflammatory cytokines have been described as etiologic factors in idiopathic recurrent miscarriage. We investigated the relation between idiopathic recurrent miscarriage and polymorphisms in the gene encoding for the interleukin 1 receptor antagonist, an indigenous modulator of proinflammatory immune response.

DESIGN

Prospective case control study.

SETTING

Academic research institution.

PATIENT(S)

One hundred five women with a history of three or more consecutive pregnancy losses before 20 weeks of gestation and 91 healthy, postmenopausal controls with at least two live births and no history of pregnancy loss.

INTERVENTION(S)

Peripheral venous puncture.

MAIN OUTCOME MEASURE(S)

Polymerase chain reaction was performed to identify the different alleles of the gene encoding for interleukin 1 receptor antagonist.

RESULT(S)

Allele frequencies among women with idiopathic recurrent miscarriage and controls were 0.34 and 0.11, respectively, for the polymorphic allele 2 (P=.002; odds ratio: 7.4, confidence interval: 2.9--10.8) and.05 and.05, respectively, for the polymorphic allele 3 (P=.6; odds ratio: 1.3, confidence interval: 0.8--2.3). Allele 2 was present in homozygous form in 9% of women with idiopathic recurrent miscarriage. In contrast, 1% of the control women were homozygous for this allele (P<.001; odds ratio: 13.5, confidence interval: 7.5--21.8).

CONCLUSION(S)

These data support a role for allele 2 of the gene encoding for interleukin 1 receptor antagonist as genetic determinant of idiopathic recurrent miscarriage.

Biological role of interleukin 1 receptor antagonist isoforms

The interleukin 1 receptor antagonist (IL1Ra) family of molecules now includes one secreted isoform (sIL1Ra) and three intracellular isoforms (icIL1Ra1, 2, and 3). Extensive evidence indicates that the sole biological function of sIL1Ra seems to be to competitively inhibit IL1 binding to cell-surface receptors. Although intracellular IL1Ra1 may be released from keratinocytes under some conditions, the intracellular isoforms of IL1Ra may carry out additional as yet poorly defined roles inside cells. Maintenance of a balance between IL1 and IL1Ra is important in preventing the development or progression of inflammatory disease in certain organs. Both the secreted and intracellular isoforms of IL1Ra contribute to maintenance of this balance. An allelic polymorphism in intron 2 of the IL1Ra gene (IL1RN*2) predisposes to the development or severity of a variety of human diseases largely of epithelial cell origin. Both the impaired production of IL1Ra and the overproduction of IL1beta are related to the presence of this allele. Restoration of the balance between IL1Ra and IL1 through a variety of approaches is a therapeutic goal in specific chronic inflammatory diseases.

Association of two variants in IL-1beta and IL-1 receptor antagonist genes with multiple sclerosis

We studied the putative association of a C-->T polymorphism in exon-5 of IL-1beta and an 85 bp tandem repeat in intron-4 of IL-1 receptor antagonist (IL-1ra) genes with susceptibility to or outcome of MS. DNA from 122 cases from a population-based cohort in Olmsted County, MN who were previously categorized for disease severity and temporal course and 244 ethnically-matched controls were analyzed. There was no association between either polymorphism and disease susceptibility. Allele-2 of IL-1beta and allele-3 of the IL-1ra polymorphisms were associated with a favorable outcome (P=0.023 and P=0.030).