No association between interleukin-18 gene polymorphisms and haplotypes in Dutch sarcoidosis patients

Hardy-Weinberg disequilibrium of the IL-18 C-607A SNP suggesting selective advantage of heterozygotes

Interleukin-18 (IL-18) plays a key role in autoimmune, inflammatory, and infectious diseases. The IL-18 gene contains a C to A single nucleotide polymorphism (SNP) at position -607 (C-607A) within the promoter region, which was found to affect the promoter activity and subsequently the protein level of IL-18. We investigated this SNP in a group of healthy Singaporeans and found that CA was the most common genotype and the C allele was more prevalent than the A allele, which was not always the case in other ethnic groups. In addition, Singaporean Chinese were significantly different from Singaporean Indians in both allelic and genotypic distributions. Furthermore, significant deviations from Hardy-Weinberg equilibrium of this SNP were found in all three ethnic groups studied (Chinese, Indians, and Malays) and also in other published literature, suggesting that heterozygotes of this IL-18 C-607A SNP may have certain selective advantages.

[Sarcoidosis and genetics]

Familial features of sarcoidosis and observations in monozygotic twins affected by the condition suggest the presence of a genetic predisposition. Various genetic associations have been described with genes coding for proteins involved in immune regulation in particular at the level of interaction between T-lymphocyte and antigen presenting cell. We review the various genetic targets described with techniques ranging from classic human lymphocyte antigen genotype to genome wide linkage scans. The 6p21 region has been highlighted, which includes relevant genes such as MHC class II, BTNL2 and TNFα. These studies show that the genetics of sarcoidosis are complex, that patient sub-groups exist, which may explain some of the heterogeneity in the results of genetic studies and that the interactions between genetic and environmental factors remains to be elucidated.

Association of interleukin-18 gene polymorphism with asthma in Chinese patients

Like other allergic diseases, asthma results from multiple conditions. Asthmatic beginning and severity are mediated by both environmental and genetic factors. In asthma studies, important work is realization of the genetic background and identification of genetic factors resulting in asthma development and phenomena. Here, we investigated whether interleukin (IL)-18 single nucleotide polymorphisms (SNPs) are involved in Chinese asthma patients. IL-18 (IL-18) SNP was detected by polymerase chain reaction (PCR)-based restriction analysis in 201 patients with asthma and 60 normal controls. Significant differences were found in the genotype distribution of IL-18 SNP between asthma patients and controls (P=0.000003). Allelic frequency of the IL-18 gene distinguished asthma patients from controls (P=0.000066). The results revealed a significant difference between asthma patients and normal controls in IL-18 SNP and a statistical correlation between IL-18 polymorphisms (105A/C) and asthma formation. We concluded that Chinese who carry the C/C homozygote of the IL-18-105A/C gene polymorphism in coding regions may have a higher risk of developing asthma.

Polymorphism of interleukin-18 promoter influences the onset of kidney graft function after transplantation

It has been well recognized that the promoter polymorphisms of interleukin-18 (IL-18) influence the level of cytokine expression. In our previously published data, we showed constitutive IL-18 expression in the epithelium of renal distal tubules in patients after kidney transplantation and significantly elevated IL-18 expression during acute rejection. In this study, we evaluated the clinical significance of two functional promoter polymorphisms of the IL-18 gene at positions -607 A/C (rs1946518) and -137 C/G (rs187238) in patients after kidney transplantation and looked for associations with the onset of graft function and the incidence of rejection episodes. Promoter polymorphisms in 124 patients and 103 unrelated controls were evaluated by sequence-specific primer polymerase chain reaction and the allele, genotype and haplotype frequencies were statistically correlated. We found a statistically different distribution of the allele frequency of -607 A/C polymorphism between patients with immediate or delayed onset of kidney graft function. Data showed that the C allele, which contributes to higher IL-18 expression, is more frequent in patients with delayed onset of function (P = 0.03, odds ratio = 1.93; 95% confidence interval = 1.15-3.25). A/C single nucleotide polymorphisms of the IL-18 promoter at position -607 may influence the onset of early kidney allograft function.

Role of genetic polymorphisms in ACE and TNF-alpha gene in sarcoidosis: a meta-analysis

A great number of association studies have been performed to identify the genes involved in the etiology and prognosis of sarcoidosis. We performed a systematic review of case-control studies through the PubMed database and evaluated them for a possible inclusion into a meta-analysis in order to assess whether the reported genetic polymorphisms are the risk factors of sarcoidosis. Case-control studies with clear diagnostic criteria and interventions were included. Only investigations of a single polymorphism/gene involvement in sarcoidosis reported more than five times were selected. Aggregating data from 12 studies on ID/ACE polymorphisms, the odds ratio (OR) for sarcoidosis, if the polymorphism was considered under the dominant genetic model, was not significantly increased: 1.19 (95% CI 0.98-1.43); OR under the recessive model was 1.20 (95% CI 0.98-1.46). In seven case-control studies on -308/TNF-alpha polymorphism, the OR for sarcoidosis if the polymorphism considered under the dominant genetic model was significantly increased at 1.47 (95% CI 1.03-2.08); the OR under the recessive model was 1.39 (95% CI 0.67-2.90). In conclusion, the results showed that the TNF-alpha genotype could be a significant risk factor for sarcoidosis, whereas the risk of sarcoidosis due to the ACE genotype was not substantially elevated.

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.

Genetics of sarcoidosis: candidate genes and genome scans

Human leukocyte antigen class II allele associations and T-cell receptor beta chain bias in sarcoidosis suggest a specific disease-triggering antigen exposure in a genetically susceptible host. The cause of sarcoidosis has been elusive, but genetics provides one of the few promising avenues to further our understanding. We review the association studies and genome scans used to identify the genes involved in sarcoidosis.

Interleukin-10 and interleukin-18 promoter polymorphisms in an Italian cohort of patients with undifferentiated carcinoma of nasopharyngeal type

PURPOSE

Cytokines such as IL-10 and IL-18 seem to be involved in the inflammatory response of undifferentiated carcinoma of nasopharyngeal type (UCNT). The aim of this study was to evaluate the correlation between functional single nucleotide polymorphisms (SNPs) in the promoter region of IL-10 and IL-18 genes and the virological and clinical characteristics in a large case series of Caucasian patients suffering from UCNT, a tumor regularly associated with the Epstein Barr Virus (EBV).

METHODS

Eighty-nine patients with histologically confirmed UCNT and 130 healthy donors were included in our study. DNA was examined for the polymorphisms of IL-10 gene at positions -1082, -819, -592 by direct sequencing and IL-18 gene at position -607 and -137 by allele-specific PCR. EBV DNA serum viremia was evaluated by QC-PCR.

RESULTS

The distributions of the IL-10 and IL-18 genetic variants were not different between UCNT patients and healthy controls. The frequency of IL-10 -1082G allele, which is associated with high IL-10 expression, showed a nearly statistically significant increase in UCNT patients EBV DNA-negative as compared to healthy controls (OR=3.3 95% CI: 1.2-9.8). Subjects with C/C or C/G combined IL-18 genotypes showed an increased risk of being with Stages III-IV (OR=2.1 95% CI: 1.2-6.6).

CONCLUSION

This study was performed to improve the definition of the pathogenetic factors implicated in UCNT by addressing the correlation between cytokine polymorphisms and clinical parameters. This is the first study investigating the possible role of the IL-18 and IL-10 polymorphisms in the development and outcome of UCNT. In our genetic analysis there is no evidence for involvement of IL-10 promoter polymorphisms alone in the genetic predisposition to this tumor. On the other hand, IL18 genetic variants may represent a genetic risk factor for tumor aggressiveness.