Inflammatory bowel disease: no association between allele combinations of the interleukin (IL) I beta and IL-I receptor antagonist gene polymorphisms

Significance of IL-1RA Polymorphism in Iranian Patients with Inflammatory Bowel Disease

BACKGROUND AND AIM

Interleukin (IL)-1 family members play an important role in the pathogenesis of inflammatory bowel disease (IBD). There are conflicting results regarding the association of IL-1 gene cluster single nucleotide polymorphisms (SNPs) with IBD and its clinical features. The aim of this study was to examine IL-1α -889 C/T, IL-1β -511 C/T, IL-1β +3962 C/T, IL-1R Pst-I1970 C/T, and IL-1RA Mspa-I11100 C/T SNPs in Iranian patients.

METHODS

In this study, SNPs of IL-1 family members were investigated in 75 patients with IBD (40 CD and 35 UC), using polymerase chain reaction with sequence-specific primers method.

RESULTS

IL-1β -511 CC genotype was significantly less present in UC compared to controls, while IL-1RA Mspa-I11100 CC was significantly associated with both Crohn's disease (CD) and ulcerative colitis (UC). IL-1α -889 TT genotype was more frequently associated with extraintestinal manifestations. A significant association was observed between IL-1β +3962 TT genotype and the disease activity in IBD. IL-1RA Mspa-I11100 CC was significantly less frequent in CD patients who need immunosuppressive therapy. IL-1RA Mspa-I11100 CT was associated with earlier age of onset in IBD, while TT genotype was associated with higher age of onset in IBD.

CONCLUSIONS

IL-1 SNPs seem to be associated with IBD and could affect the disease severity as well.

The polymorphism rs3024505 proximal to IL-10 is associated with risk of ulcerative colitis and Crohns disease in a Danish case-control study

Background

Crohns disease (CD) and ulcerative colitis (UC) are characterized by a dysregulated inflammatory response to normal constituents of the intestinal flora in the genetically predisposed host. Heme oxygenase-1 (HO-1/HMOX1) is a powerful anti-inflammatory and anti-oxidant enzyme, whereas the pro-inflammatory interleukin 1β (IL-1β/IL1B) and anti-inflammatory interleukin 10 (IL-10/IL10) are key modulators for the initiation and maintenance of inflammation. We investigated whether single nucleotide polymorphisms (SNPs) in the IL-1β, IL-10, and HO-1 genes, together with smoking, were associated with risk of CD and UC.

Methods

Allele frequencies of the IL-1β T-31C (rs1143627), and IL-10 rs3024505, G-1082A (rs1800896), C-819T (rs1800871), and C-592A (rs1800872) and HO-1 A-413T (rs2071746) SNPs were assessed using a case-control design in a Danish cohort of 336 CD and 498 UC patients and 779 healthy controls. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by logistic regression models.

Results

Carriers of rs3024505, a marker polymorphism flanking the IL-10 gene, were at increased risk of CD (OR = 1.40, 95% CI: 1.06-1.85, P = 0.02) and UC (OR = 1.43, 95% CI: 1.12-1.82, P = 0.004) and, furthermore, with risk of a diagnosis of CD and UC at young age (OR = 1.47, 95% CI: 1.10-1.96) and OR = 1.35, 95% CI: 1.04-1.76), respectively). No association was found between the IL-1β, IL-10 G-1082A, C-819T, C-592A, and HO-1 gene polymorphisms and CD or UC. No consistent interactions between smoking status and CD or UC genotypes were demonstrated.

Conclusions

The rs3024505 marker polymorphism flanking the IL-10 gene was significantly associated with risk of UC and CD, whereas no association was found between IL-1β or HO-1 gene polymorphisms and risk of CD and UC in this Danish study, suggesting that IL-10, but not IL-1β or HO-1, has a role in IBD etiology in this population.

-137 (G/C) IL-18 promoter polymorphism in patients with inflammatory bowel disease

OBJECTIVE

There is strong evidence that genetic factors contribute to the susceptibility for inflammatory bowel diseases (IBD). Recently, IL-18 promoter polymorphisms were characterized as risk factors for inflammatory diseases such as sepsis, asthma and adult-onset Still's disease. The aim of this study was to determine whether the -137 (G/C) IL-18 promoter polymorphism was associated with IBD susceptibility.

MATERIAL AND METHODS

For association analysis, 470 patients with Crohn's disease (CD), 235 unrelated patients with ulcerative colitis (UC) and 347 controls were enrolled. Furthermore, 233 UC and 470 CD trios were included for segregation analysis. Genotyping was performed by application of the TaqMan MGB biallelic discrimination system.

RESULTS

When comparing genotype frequencies of CD and UC patients versus controls, no significant difference was found (p=0.089 and p=0.078, respectively). However, the Cochran-Armitage trend test revealed a rising probability for CD and UC with increasing number of G alleles (p=0.030 and 0.028, respectively) for the case-control analysis. On the contrary, the family-based transmission disequilibrium test (TDT) did not show an association of the G allele with CD or UC in 470 CD and 233 UC trios (p=0.53 and p=0.79, respectively).

CONCLUSION

The -137 (G/C) IL-18 promoter polymorphism is not a susceptibility factor for IBD in a German cohort.

Are pANCA, ASCA, or cytokine gene polymorphisms associated with pouchitis? Long-term follow-up in 102 ulcerative colitis patients

OBJECTIVE

Pouchitis is the most frequent complication after ileal pouch-anal anastomosis for ulcerative colitis. This study aims to analyze the frequency and characteristics of pouchitis in long-term follow-up in a large population, and to determine whether a significant association exists between five immunogenetic markers and pouchitis.

METHODS

From a population of over 500 ulcerative colitis patients who had undergone ileal pouch-anal anastamosis 5-12 yr earlier, 102 subjects participated in the study. Using clinical data obtained from interviews and chart reviews, patients were classified into three groups: no pouchitis; 1-2 episodes per year; and >2 episodes per year. Coded sera from the patients were analyzed for ulcerative colitis-associated perinuclear antineutrophil cytoplasmic antibodies and Crohn's disease-associated anti-saccharomyces cerevesiae antibodies. Interleukin-1 receptor antagonist, tumor necrosis factor (TNF), and lymphotoxin beta (lymphotoxin) polymorphisms were also analyzed.

RESULTS

Pouchitis affected 49% of the study population. Antineutrophil cytoplasmic antibodies, anti-saccharomyces cerevesiae antibodies, and lymphotoxin-beta polymorphisms were not associated with pouchitis. Carriage of interleukin-1 receptor antagonist allele 2 was significantly greater among those without pouchitis than those with pouchitis. Patients without pouchitis had a significantly greater carriage rate of TNF allele 2.

CONCLUSIONS

Perinuclear antineutrophil cytoplasmic antibodies and anti-saccharomyces cerevesiae antibodies are not correlated with pouchitis, but interleukin-1 receptor antagonist and TNF may play a role in its development. Further evaluation of these markers in pouchitis will require larger populations, long-term prospective observation, and studies that correlate polymorphisms with specific immunologic functions.

Cytokine gene polymorphisms and the susceptibility to liver cirrhosis in patients with chronic hepatitis C

BACKGROUND

The speed of fibrosis progression varies considerably between patients with chronic hepatitis C. This study analyzed whether cytokine gene polymorphisms are associated with a progressive course of the disease.

METHODS

Leukocyte DNA from 101 patients with chronic hepatitis C, 52 patients with hepatitis C virus (HCV)-induced cirrhosis and 200 Caucasian blood donors was prepared. Using PCR, RFLP and PAGE, gene polymorphism analysis of the interleukin (IL)1alpha( - 889), IL1beta( - 511 and +3954), IL1 receptor agonist (RA)(intron2 VNTR), IL4(intron3 VNTR) and TNFalpha( - 308) loci was performed.

RESULTS

Of the polymorphisms analyzed, IL1beta( - 511) and IL1RA(intron2 VNTR) were unevenly distributed between the study groups. The IL1 (- 511)*A2A2 genotype occurred significantly more often in chronic hepatitis C and HCV-induced liver cirrhosis than in the controls (P < 0.01, P < 0.05, respectively). Patients with HCV-induced cirrhosis displayed a significantly higher frequency of the IL1RA(intron2 VNTR)*A2 polymorphism than patients with chronic hepatitis C and controls (P < 0.05).

CONCLUSIONS

Although the IL1beta( - 511)*A2A2 genotype may increase the susceptibility to acquire chronic hepatitis C and IL1RA(intron2 VNTR)*A2 polymorphism is associated with disease progression to cirrhosis, our results indicate that the analyzed cytokine gene polymorphisms have an overall low impact on the natural course of chronic hepatitis C infection.

Update on the genetics of inflammatory bowel disease

There is a general consensus that interplay of genetic and environmental factors leads to an overactive mucosal immune response, which mediates the tissue damage in inflammatory bowel disease. Ethnic aggregation of inflammatory bowel disease (particularly, increased incidence and prevalence in the Ashkenazim), familial aggregation of inflammatory bowel disease, and greater concordance for inflammatory bowel disease in monozygotic twins than dizygotic twins are 3 lines of evidence for a central role of genetic factors in the pathogenesis. The genetics of inflammatory bowel disease cannot be explained by simple Mendelian genetics; it is characterized by incomplete penetrance, multiple susceptibility loci and genetic heterogeneity. Unraveling the complex genetics of inflammatory bowel disease is a daunting challenge, but the perseverance of inflammatory bowel disease gene hunters has produced commendable results in recent years. Since 1996, the field of inflammatory bowel disease genetics has progressed from publication of the first systematic genome searches for inflammatory bowel disease susceptibility loci to the identification of Crohn disease-associated genetic variants in CARD15/NOD2. Strategies for finding additional inflammatory bowel disease genes include taking advantage of the greater resolution and power of linkage disequilibrium mapping, mapping by admixture disequilibrium in African-American and Hispanic-American populations, stratifying genetic analyses by genotypes at known inflammatory bowel disease loci, and refining inflammatory bowel disease phenotypes to reduce genetic heterogeneity and simplify the search for additional inflammatory bowel disease genes.

DNA variants in cytokine and NOD2 genes, exposures to infections and risk for Crohn's disease

The incidence and prevalence of Crohn's disease (CD) among children in developed countries is increasing. Although extensive progress has been made in the elucidation of the pathogenesis of the disease, its mechanism remains unknown. CD is likely to be the result of a complex interplay of both genetic and environmental factors (G x E). However, the specific elements underlying these interactions have not been defined. We propose that the underlying pathology of CD may be related to interactions between infections acquired either during intrauterine life and/or early childhood and DNA variants in the cytokine and the NOD2 genes. DNA variants in the latter could confer susceptibility by altering immune development and response to infectious agents. We present a molecular and epidemiological perspective on possible mechanisms underlying G x E. Investigating these and other pathways will be paramount for the appropriate identification of susceptible populations, so that preventive and/or therapeutic interventions could be adequately targeted.

Proinflammatory genotype of interleukin-1 and interleukin-1 receptor antagonist is associated with ESRD in proteinase 3-ANCA vasculitis patients

BACKGROUND

Small-vessel vasculitides are associated with antineutrophil cytoplasmic antibodies (ANCAs). Cytoplasmic ANCAs are targeted mainly against proteinase 3 (PR3), whereas myeloperoxidase (MPO) is the major antigen of perinuclear ANCAs. These relapsing vasculitides show heterogeneous clinical pictures, and disease severity may vary broadly from mild local organ manifestation to acute organ failure (eg, renal failure). We tested whether two cytokine polymorphisms in the interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra) genes, known to determine cytokine secretion, are associated with clinical manifestations and outcome of ANCA-associated vasculitides.

METHODS

Polymerase chain reaction and restriction fragment length polymorphism analyses were performed to determine polymorphisms in the IL-1beta and IL-1ra genes in 79 patients with PR3-ANCA, 30 patients with MPO-ANCA vasculitis, and 196 healthy controls.

RESULTS

The frequency of the so-called proinflammatory genotype, characterized by high secretion of IL-1beta and low secretion of its antagonist IL-1ra, was increased significantly in patients with PR3-ANCA with end-stage renal disease.

CONCLUSION

Patients with a renal manifestation of PR3-ANCA vasculitis have an increased risk for developing end-stage renal disease when carrying the proinflammatory IL-1beta/IL-1ra genotype. Anti-inflammatory therapy specifically antagonizing the proinflammatory effect of IL-1beta may be a promising treatment for patients with Wegener's granulomatosis with renal manifestations.

The genetics of inflammatory bowel disease

The complex genetics of IBD is characterized by more than one susceptibility locus, genetic heterogeneity, incomplete penetrance, and probable gene-gene and gene-environment interactions. Functional candidate gene association studies during the past few decades have revealed only modest associations between IBD and genetic variants in the HLA genes and a limited number of other genes that are involved in immune regulation and the inflammatory response. Important advances in IBD genetics research have come about from systematic genome searches for IBD loci. The identification of Crohn's disease-associated NOD2 genetic variants that appear to alter the innate immune response to bacteria is a seminal finding that perhaps is the greatest advance toward understanding the pathogenesis of IBD in decades. The future discovery of other IBD genetic risk factors, facilitated by the completion of the human genome sequencing and annotation, may allow the development of better therapies, possibly including preventive therapies, for patients with Crohn's disease and ulcerative colitis.

Failure to detect an association with IL1 genotypes in European Caucasians with generalised early onset periodontitis

OBJECTIVES

In order to elucidate the genetic background to EOP it is useful to investigate associations with genetic polymorphisms of immune response genes, whose products play a r le in the inflammatory process. The aim of this study was to examine IL1A and IL1B genetic polymorphisms in unrelated European white Caucasian patients with generalised early-onset periodontitis (GEOP).

MATERIAL AND METHODS

Polymerase chain reaction (PCR) amplification of the ILIA (-889) gene and IL1B (+3953) gene (56 patients, 56 controls) was carried out and PCR products subjected to restriction fragment length polymorphism (RFLP) analysis.

RESULTS

There were no significant differences between patients and controls for any of the genotype or allele frequencies investigated (p = 1.0). Smoking status was also included as a covariate but this did not alter the results. Furthermore, expression of the composite genotype described by Kornman and coworkers was also investigated in these subjects. No significant differences were found between patients and controls whether smoking was included as a covariate or not.

CONCLUSION

The lack of any association between the IL1 polymorphisms and GEOP, in the population presented here, brings into doubt the usefulness of these candidate genes as markers of susceptibility to this form of periodontitis.

Promoter polymorphisms of the genes encoding tumor necrosis factor-alpha and interleukin-1beta are associated with different subtypes of psoriasis characterized by early and late disease onset

The psoriatic inflammatory process is characterized by an overexpression of pro-inflammatory cytokines such as tumor necrosis factor-alpha and interleukin-1beta compared with a relative deficiency of anti-inflammatory factors such as interleukin-10 and the interleukin-1 receptor antagonist (interleukin-1Ra). Gene polymorphisms that affect cytokine production may contribute to the disease-associated cytokine imbalance and influence susceptibility to psoriasis. Here, we investigated the relationship between polymorphisms in the genes encoding for tumor necrosis factor-alpha (G-238A, G-308A), interleukin-1beta (C-511T, T+3953C), and interleukin-1Ra (intron 2), and cytokine production in peripheral blood mononuclear cells of healthy donors, and analyzed the distribution of these polymorphisms in patients with psoriasis vulgaris (n = 231) and healthy controls (n = 345). Carriage of tumor necrosis factor A-238 allele 2 (-238*A) was associated with increased production of tumor necrosis factor-alpha in response to lipopolysaccharide in vitro, and with early onset disease (< 40 y), especially in male patients with psoriasis [32% vs 7% in male controls; odds ratio = 6.78, 95% confidence interval = (3.18-15.15), p(adjusted) = 2 x 10(-7)]. Carriage of the interleukin-1B-511*1 (-511*C) homozygous genotype was associated with increased production of interleukin-1Ra in response to lipopolysaccharide and interleukin-10, and with late onset psoriasis [> or = 40 y; 61% vs 44% in controls; odds ratio = 2.04, 95% confidence interval = (1.19-3.53), p(adjusted) = 0.0419]. These findings indicate that gene polymorphisms associated with altered cytokine responses in vitro may modify age of onset of psoriasis. They also provide further evidence that patients with early and late onset psoriasis differ in their genetic background.

Lack of association with interleukin 1 receptor antagonist and interleukin-1beta gene polymorphisms in sarcoidosis patients

Interleukin-1beta (IL-1beta) and its endogenous antagonist, the interleukin-1 receptor antagonist (IL-1ra), play important roles in immune responses. In sarcoidosis, IL-1beta is reported to be increased whereas IL-1ra is decreased. It has recently been shown that polymorphisms in the IL-1ra and IL-1beta genes may account for variation in the two proteins. These polymorphisms are also reported to be associated with several autoimmune diseases. Since this might be expected to affect sarcoidosis, an investigation of 108 sarcoidosis patients and 113 healthy control subjects was performed. The IL-1ra genotype was determined using the polymerase chain reaction (PCR), and the IL-1beta genotype by PCR restriction fragment length polymorphism. We found no significant differences in IL-ra and IL-1beta genotypes between sarcoidosis patients and healthy controls. Furthermore, there was no association between the IL-1beta genotype and the roentgenographic stage, disappearance of chest X-ray shadows or organ involvement. In conclusion, there is no bias in the IL-1ra and IL-1beta genotype in Japanese sarcoidosis patients.

Neither IL-1beta, IL-1 receptor antagonist, nor TNF-alpha polymorphisms are associated with susceptibility to COPD

The cytokines that contribute to airway inflammation, including interleukin-1beta (IL-1beta) and tumour necrosis factor alpha (TNFalpha), might have key roles in the development of chronic obstructive pulmonary disease (COPD). Interleukin-1 receptor antagonist (IL-1RN), the physiological antagonist of IL-1beta, is also known to play a crucial role in several chronic inflammatory diseases. In this study, we investigated the association of the polymorphisms of IL-1beta, IL-1RN and TNFalpha with susceptibility to COPD. To elucidate the genotype of the IL-1beta polymorphisms at position -511 base and at the amino acid residue 105, the IL-1RN polymorphism in intron 2, and TNFalpha polymorphism at position -308, polymerase chain reaction (PCR) and restriction enzyme fragment length polymorphism (RFLP) were performed on blood samples from both patients with COPD (n = 53) and control subjects (n = 65). There were no differences on the allele and genotype frequency of IL-1beta, IL-1RN, and TNFalpha between the two groups. We could not find a significant link between the polymorphism of TNFalpha, which was previously reported to be associated with chronic bronchitis, and COPD. Furthermore, no association between genetic polymorphisms of IL-1beta and IL-1RN and individual susceptibility to COPD was found.

Interleukin 6, tumour necrosis factor alpha, interleukin 1beta and interleukin 1 receptor antagonist promoter or coding gene polymorphisms in multiple myeloma

Proinflammatory cytokines such as interleukin 6 (IL-6), tumour necrosis factor alpha (TNF-alpha) and IL-1beta are considered to be involved in the pathogenesis of multiple myeloma (MM). In the present study, we examined a G/C polymorphism at position -174 in the promoter region of IL-6, a biallelic polymorphism at position -308 in the promoter region of TNF-alpha, the TaqI restriction fragment length polymorphism in exon 5 of IL-1beta and a variable number of identical tandem repeat polymorphisms in intron 2 of IL-1 receptor antagonist (IL-1Ra) genes. The alleles of these loci are known to influence the level of production of the cytokines and the IL-1Ra. Seventy-three patients with MM, 27 with monoclonal gammopathy of undetermined significance (MGUS) and 129 healthy individuals were included. No difference was found between patients and healthy controls or between MM and MGUS patients in the distributions of genotypes and frequencies of alleles of the IL-6 (-174), TNF-alpha (-308), IL-1beta TaqI and IL-1Ra gene polymorphisms. No associations between the polymorphisms at the loci under study and clinical factors such as age, sex, clinical stage at onset and M-protein type were observed. Our results indicate that the cytokine (IL-6, TNF-alpha and IL-1beta) and IL-Ra gene polymorphisms do not confer susceptibility to the development of MM.

Genetics and inflammatory bowel disease

Genetic factors have a definite role in the etiology of inflammatory bowel disease (IBD). The mode of inheritance suggests a polygenic disease with the penetrance of the genetic factors being strongly influenced by the lifestyle of an industrialized society. Molecular techniques, which have become available through the progress of the human genome project, allowed a first series of linkage studies in pairs of affected siblings with IBD, which suggested multiple genomic susceptibility regions. These regions are still large, but considerable progress is being made toward the identification of actual disease genes. It is hoped that an understanding of the genetic etiology of IBD will lead to enhanced diagnostic procedures, more effective therapeutic interventions, and preventive strategies in the future.

Significant differences in the interleukin-1beta and interleukin-1 receptor antagonist gene polymorphisms in a Hungarian population with inflammatory bowel disease

BACKGROUND

There is growing evidence of the importance of genetic predisposition and the activation of the mucosal immune system in the pathogenesis of inflammatory bowel disease. Thus, genes involved in the regulation of inflammation are receiving increased attention. We have studied whether Crohn's disease (CD) or ulcerative colitis (UC) is associated with certain allelic combinations of IL1B/IL1RA gene polymorphisms in a different European population than the ones studied so far.

METHODS

Ninety-six patients with UC, 97 with CD, and 132 healthy individuals (HC) were typed for the polymorphic regions in exon 5 of the IL1B gene and in intron 2 of the IL1RA gene, using polymerase chain reaction-based methods.

RESULTS

In CD homozygotes for allele 1 in IL1B gene polymorphism were more often present (72% versus 28%; P = 0.01) in the subgroup of patients carrying at least one copy of allele 2 in IL1RA gene polymorphism. This association was not found in HC (HC versus CD; P = 0.03) or UC. However, in UC patients with pancolitis a similar trend was observed (75% versus 25%). Several genotype combinations characterized by the presence of allele 2 of the IL1RA gene polymorphism were more common in CD (P = 0.001) and UC (P = 0.049) than in HC.

CONCLUSIONS

Our data support the concept that CD and severe UC have a genetic disequilibrium in the distribution of IL1B and IL1RA gene polymorphisms. These findings together with functional studies will contribute to the understanding of the pathogenesis of the chronicity of inflammation in these diseases.