Interleukin-18 promoter polymorphisms in type 1 diabetes

Relationships between Interleukin 18 -607 C/A and -137 G/C, Osteopontin -9250 C/T Genetic Polymorphisms and Systemic Inflammatory Response Syndrome in Coronary Artery Bypass Graft Surgery

Background and Objectives: Systemic inflammatory response syndrome (SIRS) is one of the most significant complications after on-pump heart surgery procedures. High cytokine levels have been shown after open-heart surgeries and a genetic predisposition seems to be an important underlying modulatory characteristic for SIRS. To investigate the association between interleukin 18 -607 C/A, interleukin 18 -137 G/C and osteopontin 9250 C/T genetic polymorphisms and SIRS in on-pump CABG patients. Materials and Methods: Two hundred consecutive elective on-pump CABG patients were recruited prospectively to the study. Genomic DNA was extracted from whole blood and genotyping was determined by sequence specific PCR or PCR-RFLP methods for related polymorphisms. Results: SIRS incidence was 60.2%, 38.1%, 18.9% on postoperative day 1, 2 and 3, respectively, in the whole study population. The SIRS rate on the second postoperative day was 13% and 43.4%, respectively, in osteopontin 9250 C/T T allele non-carriers and carriers (p = 0.004). WBC (White Blood Cell) counts were higher on day 2 and 3 in osteopontin 9250 C/T T allele carriers compared to non-carriers (day 2; 12.7 ± 4 vs. 10.5 ± 2.4 (p = 0.015), day 3; 11.8 ± 4 vs. 9.1 ± 4.7 (p = 0.035)). The average ICU stay was 3.1 ± 7.4, 1.28 ± 0.97 for IL 18-137 G/C C allele carriers and non-carriers, respectively (p = 0.003), and in the IL 18-137 G/C C allele carriers, SIRS developed in 42.2% by the second postoperative day whereas the rate was 57.8% in non-carriers (p = 0.025). Conclusions: The current research revealed a possible link between osteopontin 9250 C/T and IL18-137 G/C genetic polymorphism and SIRS and morbidity in on-pump CABG patients.

Protective effects of IL18-105G > A and IL18-137C > Ggenetic variants on severity of COVID-19

OBJECTIVE AND DESIGN

A cross-sectional study evaluated the IL18-105G > A (rs360717) and IL18-137C > G (rs187238) variants on Coronavírus Disease 2019 (COVID-19) severity.

SUBJECTS AND METHODS

528 patients with COVID-19 classifed with mild (n = 157), moderate (n = 63) and critical (n = 308) disease were genotpyed for the IL18-105G > A and IL18-137C > G variants.

RESULTS

We observed associations between severe + critical COVID-19 groups (reference group was mild COVID-19) and the IL18-105G > A (p = 0.008) and IL18-137C > G (p = 0.01) variants, which remained significant after adjusting for sex, ethnicity and age. Consequently, we have examined the associations between moderate + critical COVID-19 and the genotypes of both variants using different genetic models. The IL18-105G > A was associated with severe disease (moderate + critical), with effects of the GA genotype in the codominant [Odds ratio (OR), (95 % confidence interval) 0.55, 0.34-0.89, p = 0.015], overdominant (0.56, 0.35-0.89, p = 0.014) and dominant (0.60, 0.38-0.96, p = 0.031) models. IL18-105 GA coupled with age, chest computed tomograhy scan anormalities, body mass index, heart diseases, type 2 diabetes mellitus, hypertension, and inflammation may be used to predict the patients who develop severe disease with an accuracy of 84.3 % (sensitivity: 83.3 % and specificity: 86.5 %). Therefore, the presence of the IL18-105 A allele in homozygosis or heterozygosis conferred about 44.0 % of protection in the development of moderate and severe COVID-19. The IL18-137C > G variant was also associated with protective effects in the codominant (0.55, 0.34-0.89, p = 0.015), overdominant (0.57, 0.36-0.91, p = 0.018), and dominant models (0.59, 0.37-0.93, p = 0.025). Therefore, the IL18-137 G allele showed a protective effect against COVID-19 severity.

CONCLUSION

The IL18-105G > A and IL18-137C > Gvariants may contribute with protective effects for COVID-19 severity and the effects of IL18-137C > G may be modulating IL-18 production and Th1-mediated immune responses.

Coronavirus Disease 2019 (COVID-19) Pandemic Lifestyle Changes May Have Influenced Small Bowel Microbial Composition and Microbial Resistance

BACKGROUND

The coronavirus disease 2019 (COVID-19) global pandemic necessitated many severe lifestyle changes, including lockdowns, social distancing, altered food consumption and exercise patterns, and extensive hygiene practices. These extensive changes may have affected the human gut microbiome, which is highly influenced by lifestyle.

AIMS

To examine the potential effects of pandemic-related lifestyle changes on the metabolically relevant small bowel microbiome.

METHODS

Adult subjects presenting for upper endoscopy without colonoscopy were identified and divided into two matched groups: pre-pandemic (February 2019-March 2020) and intra-pandemic (April 2021-September 2021, all COVID-19 negative). Duodenal aspirates and blood samples were collected. Duodenal microbiomes were analyzed by 16S rRNA sequencing. Serum cytokine levels were analyzed by Luminex FlexMap3D.

RESULTS

Fifty-six pre-pandemic and 38 COVID-negative intra-pandemic subjects were included. There were no significant changes in duodenal microbial alpha diversity in the intra-pandemic vs. pre-pandemic group, but beta diversity was significantly different. The relative abundance (RA) of phylum Deinococcus-Thermus and family Thermaceae, which are resistant extremophiles, was significantly higher in the intra-pandemic vs. pre-pandemic group. The RA of several Gram-negative taxa including Bacteroidaceae (phylum Bacteroidetes) and the Proteobacteria families Enterobacteriaceae and Pseudomonadaceae, and the RA of potential disruptor genera Escherichia-Shigella and Rothia, were significantly lower in the intra-pandemic vs. pre-pandemic group. Circulating levels of interleukin-18 were also lower in the intra-pandemic group.

CONCLUSIONS

These findings suggest the small bowel microbiome underwent significant changes during the pandemic, in COVID-19-negative individuals. Given the key roles of the small bowel microbiota in host physiology, this may have implications for human health.

Genetic polymorphisms -137 (G > C) (rs187238) and -607 (C > A) (rs1946518) and serum level of interleukin 18 in Fars ethnic groups with metabolic syndrome in Northern Iran

INTRODUCTION

We aimed to determine the genetic polymorphisms and serum level of interleukin 18 in Fars ethnic groups.

MATERIAL AND METHODS

226 Fars ethnic groups were participated. The ATP III criteria were used to assess MS components. The SNPs of the IL-18 gene were determined with ARMS-PCR.

RESULTS

The GG, GC, and CC genotypes of -137 were 50%, 40%, and 10%. The CC, CA, and AA genotypes of -607 were 45%, 37%, and 18%. The GG, GC, and CC genotypes of -137 were 44.20%, 43.40%, and 12.40%, and were 55.75%, 36.28%, and 7.97% in subjects with and without MS, respectively. The CC, CA, and AA genotypes of -607 were 48.70%, 37.20%, and 14.20% and were 41.60%, 37.20%, and 21.20% in both groups, respectively.

CONCLUSION

IL-18 gene may different in specific populations, different ethnic groups and geographic regions. The IL-18 polymorphisms might not be used as a marker of metabolic syndrome.

Interleukin-18 in metabolism: From mice physiology to human diseases

Interleukin-18 (IL-18) is a classical member of the IL-1 superfamily of cytokines. As IL-1β, IL-18 precursor is processed by inflammasome/caspase-1 into a mature and biologically active form. IL-18 binds to its specific receptor composed of two chains (IL-18Rα and IL-18Rβ) to trigger a similar intracellular signaling pathway as IL-1, ultimately leading to activation of NF-κB and inflammatory processes. Independently of this IL-1-like signaling, IL-18 also specifically induces IFN-γ production, driving the Th1 immune response. In circulation, IL-18 binds to the IL-18 binding protein (IL-18BP) with high affinity, letting only a small fraction of free IL-18 able to trigger receptor-mediated signaling. In contrast to other IL-1 family members, IL-18 is produced constitutively by different cell types, suggesting implications in normal physiology. If the roles of IL-18 in inflammatory processes and infectious diseases are well described, recent experimental studies in mice have highlighted the action of IL-18 signaling in the control of energy homeostasis, pancreatic islet immunity and liver integrity during nutritional stress. At the same time, clinical observations implicate IL-18 in various metabolic diseases including obesity, type 1 and 2 diabetes and nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). In the present review, we summarize and discuss both the physiological actions of IL-18 in metabolism and its potential roles in pathophysiological mechanisms leading to the most common human metabolic disorders, such as obesity, diabetes and NAFLD/NASH.

Association between IL-18 and IL-6 gene polymorphisms and the risk of T1D in Egyptian children

Purpose

To test the involvement between IL-18 and IL-6 genetic polymorphisms and susceptibility to Type 1 diabetes (T1D).

Methods

Single nucleotide polymorphisms (SNPs) at positions -607A/C and - 137G/C in IL-18 promoter region were examined by sequence specific primers-polymerase chain reaction (SSP-PCR) and position -174G/C in promoter region of IL-6 gene which analyzed by Mutagenically Separated PCR (MS-PCR) in 104 T1D participants and 114 controls.

Results

IL-18 -137GC and -137CC genotypes and -137C allele were significantly decreased in T1D subjects (P < 0.05), while -137GG genotype was insignificantly increased as compared to controls. A significant decrease was detected in haplotype -137C/-607C frequency in T1D participants compared with controls (OR = 0.04, P < 0.001). There was significant association between IL-18 -607 of (CC, AC and AA genotypes) in age at diagnosis, glycated hemoglobin (HbA1c) and higher body mass index (BMI) (P < 0.05).

Conclusion

This study demonstrated that IL-18 gene promoter polymorphisms might be associated with susceptibility to T1D in Egyptian children. Individuals carrying CC genotype at position -137 of IL-18 promoter may be at a low risk of T1D progression. Additionally, the susceptible combination of IL-18 and IL-6 cytokine genes associated with T1D highlight their risk toward the disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00763-w.

Associations between interleukin 18 gene polymorphisms and susceptibility to vasculitis: A meta-analysis

Interleukin 18 (IL18), a pro-inflammatory cytokine, affects the development and progress of vasculitis. The production, expression, and function of this cytokine are affected by polymorphisms of promoter region of the IL18 gene. In this study, a meta-analysis of the associations between several IL18 polymorphisms and susceptibility to vasculitis was performed. Published literature from PubMed and Embase were retrieved. In total, nine studies comprising 1006 patients with vasculitis and 1499 controls combined, and the investigating the rs187238, rs194618, and rs360719 polymorphisms of the promoter region of the IL18 gene, were included in the meta-analysis. Pooled odds ratios (OR) and 95% confidence intervals (CI) were estimated with fixed-effects model or random-effects model. The recessive model of the rs194618 polymorphism was found to be significantly associated with a high susceptibility to vasculitis (OR = 1.54, 95% CI = 1.02–2.33, P = 0.04), especially in the Mongoloid race, where the A allele of rs194618 was associated with a low risk of the disease (OR = 0.77, 95% CI = 0.62–0.95, P = 0.01). By contrast, the rs187238 and rs360719 polymorphisms were not associated with this inflammatory condition. This meta-analysis showed that some IL18 polymorphisms are associated with susceptibility to vasculitis. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (2): 203-211)

IL-18 polymorphisms (-137C/G and -607A/C) are not associated with tuberculosis

Many studies have demonstrated that (IL-18) polymorphisms (including -137C/G and -607A/C) are correlated with the risk of tuberculosis. However, the meaning of this finding remains a matter of debate. In this study, electronic databases, including PubMed, EMBASE, Web of Science, Google Scholar and CNKI, were systemically queried to identify relevant studies. Subsequently, odds ratios and corresponding 95% confidence intervals were analysed. Our data indicated that the IL-18 -137C/G polymorphism was not related to tuberculosis susceptibility (GG vs. AA odds ratio = 0.71, 95% confidence interval 0.43–1.17; GA vs. AA: odds ratio =0.80, 95% confidence interval 0.57–1.13; dominant model: odds ratio = 0.78, 95% confidence interval 0.56–1.08; recessive model: odds ratio = 0.76, 95% confidence interval 0.46–1.25). Similarly, there was no association between the IL-18 -607A/C polymorphism and tuberculosis susceptibility (AA vs. CC: odds ratio = 1.25, 95% confidence interval 0.87–1.79; CA vs. CC: odds ratio = 1.10, 95% confidence interval 0.93–1.29; dominant model: odds ratio = 1.13, 95% confidence interval 0.90–1.41; recessive model: odds ratios=1.17, 95% confidence interval 0.90–1.53). No association was found in the subgroup analysis based on the Hardy–Weinberg equilibrium. In addition, there was no publication bias. The two IL-18 gene polymorphisms (-137C/G and -607A/C) were not markedly correlated with tuberculosis susceptibility. Well-designed studies with more subjects will be required for further validation of these results.

Impact of functional IL-18 polymorphisms on genetic predisposition and diverse clinical manifestations of the disease in Indian SLE patients

Several studies have demonstrated associations between interleukin-18 polymorphisms and risk of systemic lupus erythematosus in different populations except one of Indian origin. We therefore investigated for the influence of interleukin-18 (-1297T/C, -607A/C, -137G/C; + 105A/C) polymorphisms on genetic susceptibility and clinical expression of the disease in Indian systemic lupus erythematosus patients. A total of 200 systemic lupus erythematosus patients and 201 controls were recruited. Genotyping of interleukin-18 polymorphisms were performed by polymerase chain reaction-restriction fragment length polymorphism. Serum interleukin-18 levels were measured by enzyme-linked immunosorbent assay. Interleukin-18 (-1297T/C; -137G/C) polymorphisms showed significant association with genetic susceptibility to the disease in our systemic lupus erythematosus cohort. Stratification analysis revealed -1297CC and -1297C associated with renal involvement (odds ratio = 3.4, correcting p value = 0.0207), (odds ratio = 2.0, correcting p value = 0.0054) respectively. Additionally, -1297C allele frequency was significantly increased in patients with anti-nucleosome antibody (odds ratio = 2.1, correcting p value = 0.0301). Haplotype analysis showed CC haplotype strongly associated with serositis (odds ratio = 9.1, correcting p values = 0.0009) and neurologic involvement (odds ratio = 9.3, correcting p value = 0.0018). We reported a 2.7-fold increase in serum interleukin-18 levels in patients (511.5 ± 242.3 pg/ml) compared to controls (189.4 ± 80.8 pg/ml) ( p < 0.0001). Furthermore, interleukin-18 levels were positively correlated with disease activity ( r = 0.548, p = 0.0001) and renal involvement in the patients with lupus nephritis ( r = 0.569, p < 0.0001). In summary, interleukin-18 polymorphisms elucidated in this study appear to confer genetic susceptibility to the disease and are associated with renal, serositis and neurologic involvement in Indian systemic lupus erythematosus patients.

IL-6 and IL-18 cytokine gene variants of pulmonary tuberculosis patients with co-morbid diabetes mellitus and their household contacts in Hyderabad

PURPOSE

Association of cytokine genes reflects their susceptibility towards infection and disease in household contacts (HHC) of pulmonary tuberculosis (PTB) patients. Hyperglycemia, a common factor in diabetics might influence their risk towards mycobacterium tuberculosis infection and disease development. This study determines the association of IL-6 and IL-18 cytokine gene variants of TB patients with diabetes mellitus (TBDM) and their HHC in Hyderabad.

METHODS

Single nucleotide polymorphisms of IL-6 (-174 G>C and -572 G>C) and IL-18 (-137 G>C and -607 C>A) cytokine genes were genotyped by Amplification Refractory Mutation System and Restriction Fragment Length polymerase chain reaction in total of 705 subjects comprising of TBDM, their HHC, PTB, DM and Healthy controls (HC).

RESULTS

At IL-6 -174G>C variant, GG genotype, G allele in TBDM and TBDM HHC, at -572G>C variant, C allele in TBDM and GG haplotype in TBDM HHC were showing positive association, however DM have not shown any association at IL-6 polymorphic sites. With respect to the IL-18 gene polymorphisms, at -137 G>C variant, GG genotype was positively associated in PTB while at -607 C>A variant positive association was shown with AC genotype in TBDM, their HHC and DM; GACC diplotype in TBDM and GCGC in PTB.

CONCLUSION

Our findings suggest that susceptible combination of IL-6 and IL-18 cytokine genes associated with disease in the HHCs highlight their risk of inclination towards the disease.

Interleukin-18 polymorphism as an inflammatory index in metabolic syndrome: A preliminary study

AIM

To assess circulatory levels of interleukin-18 (IL-18) and determine whether the presence of IL-18 promoter polymorphism influences metabolic syndrome phenotypes.

METHODS

This study recruited one hundred and eighty individuals divided into three groups with sixty subjects each as: Normal weight (18.0-22.9 kg/m²), overweight (23.0-25.9 kg/m²) and obese (> 26.0 kg/m²) according to South Asian criteria of BMI. Fasting blood glucose (FBG), Lipid profile, insulin, IL-18 and tumor necrosis factor (TNF)α were measured using ELISA kits, whereas low density lipoprotein (LDL)-cholesterol, insulin resistance (HOMA-IR) and insulin sensitivity (QUICKI) were calculated. The body fat percentage (BF) was measured through bioelectrical impedance analysis; waist and hip circumference were measured. Genotyping of IL-18 -607 C/A polymorphism was performed by using tetra-primer amplification refractory mutation system. Student t test, One-way analysis of variance, Hardy-Weinberg equilibrium, Pearson’s χ² test and Pearson’s correlation were used, where a P value < 0.05 was considered significant.

RESULTS

In an aged matched study, obese subjects showed higher levels of FBG, cholesterol, triglycerides and LDL levels as compared to normal weight (P < 0.001). Highest levels of IL-18 and TNF levels were also seen in obese subjects (IL-18: 58.87 ± 8.59 ng/L) (TNF: 4581.93 ± 2132.05 pg/mL). The percentage of IL-18 -607 A/A polymorphism was higher in overweight and obese subjects vs normal weight subjects (P < 0.001). Moreover, subjects with AA genotype had a higher BF, insulin resistance, TNFα and IL-18 levels when compared with subjects with AC (heterozygous) or CC (wild type) genotypes. However, we did not find any difference in the lipid profile between three subgroups.

CONCLUSION

This preliminary data suggests that IL-18 polymorphism affects IL-18 levels that might cause low grade inflammation, further exacerbated by increased TNFα. All these increase the susceptibility to develop MetS. Further studies are required to validate our findings.

Interleukin-18 gene polymorphism and risk of CVD in older patients with type 2 diabetes mellitus

OBJECTIVE

Interleukin-18 (IL-18), a proinflammatory cytokine, plays a key role in the acute and chronic inflammatory processes. It is associated with risk of developing cardiovascular disease (CVD). The aim of this study was to evaluate association between G(-137)C polymorphism (rs187238) in the IL-18 gene and risk of diabetes and CVD in type 2 diabetes patients.

METHODS

We examined 1548 T2DM patients and 590 controls. All subjects were genotyped for the G(-137)C promoter region polymorphism by polymerase chain reaction (PCR-SSP).

RESULTS

Genotype distribution of the G(-137)C polymorphism showed no significant difference between T2DM patients and controls (p=0.115). An association with CVD was analyzed in two age groups: ⩾65 and <65years. In patients younger than 65years there was a tendency to association of CC genotype with CAD (OR 1.87, 95% CI 1.0-3, p=0.051). In contrast, in subjects aged 65 or older, the C allele and CC genotype showed the significant association with the presence of CVD, with the OR 1.99, p=0.001 and OR 5.31, p=0.006, respectively. The C allele carriers showed the higher prevalence of CVD compared to non-carriers (61% vs. 39%, p<0.0001).

CONCLUSION

Older T2DM patients carrying the C allele of IL-18 G(-137)C polymorphism have a significantly increased risk of CVD.

Serum Interleukin-18 and Its Gene Haplotypes Profile as Predictors in Patients with Diabetic Nephropathy

BACKGROUND:

Diabetic nephropathy (DN) is known as an acute microvascular complexity as a subsequence progression in diabetes mellitus type 1 and 2. Many evidence pointed that the proinflammatory cytokine Interleukin (IL)-18 might be involved in the pathogenesis of DN.

AIM:

The current study aimed to evaluate the association of serum IL-18 and its promoter gene polymorphisms with diabetic nephropathy.

METHODS:

This study included 62 diabetic nephropathy patients (DN group) compared to 52 diabetes mellitus patients (DM group). The two groups were subjected to anthropometry assessment, molecular studies including SNP genotyping by RFLP and finally statistical analysis.

RESULTS:

The assessment of the serum IL-18 level and the frequencies of its allele and haplotype: -137G/C, -607C/A and -656G/T among the DN and DM subjects revealed that -137G allele has significant variation between DN and DM subjects (about 80.8%, P = 0.05) but, no significant variation in -607 or -656 alleles IL-18 gene promoter.

CONCLUSION:

These data confirm the impact of high serum IL-18 and the haplotype of the polymorphism located in the promoter region of the IL-18 gene with the DN.

The association of IL-18 gene promoter polymorphisms and the levels of serum IL-18 on the risk of multiple sclerosis

OBJECTIVES

Multiple sclerosis is an inflammatory condition of the central nervous system whose etiology is influenced by immunologic, genetic, and environmental factors. Aim of the present study was to determine if any relation exists between IL-18 -137C/G and -607C/A gene promoter polymorphisms on the individual susceptibility of multiple sclerosis and also to investigate the possible effect of IL-18 activity regarding this kind of polymorphism and MS.

PATIENTS AND METHODS

113 patients with clinically definite MS and 135 ethnically-matched controls were participated in this study. IL-18 -137C/G and -607C/A gene promoter polymorphisms were analyzed by Sequence Specific Polymerase Chain Reaction (SS-PCR), while levels of serum IL-18 were measured by Enzyme Linked Immunoassay Assay (ELISA) in patients with MS and healthy controls.

RESULTS

Our results showed that the IL-18 -607AA genotype indicated 6 times higher risk in the development of MS (OR=6.883; 3.17-14.96; p<0.001). According to our findings, smoking seems to be an important confounding factor in MS patients with carrying IL-18 -607 AA and CA+AA genotypes. However, no meaningful association was found with IL-18 -137C/G gene promoter polymorphism.

CONCLUSION

In conclusion, we suggest that IL-18 -607C/A gene promoter polymorphism is a major genetic factor for determining individual susceptibility to MS, where smoking status also increases the risk of MS.

Interleukin-18 promoter -607 C/A and -137 G/C polymorphisms and susceptibility to type 1 diabetes: A meta-analysis

OBJECTIVE

The aim of this study was to determine whether the functional interleukin-18 (IL-18) promoter -607 C/A (rs1946518) and -137 G/C (rs187238) polymorphisms are associated with susceptibility to type 1 diabetes (TID).

METHODS

A meta-analysis was conducted to assess the associations between the IL-18 -607 C/A and -137 G/C polymorphisms and T1D in overall and by ethnic group.

RESULTS

A total of 6075 cases and 5744 controls from ten studies were considered in this meta-analysis. In all study subjects, the meta-analysis showed no association between T1D and the IL-18 -607 C allele (OR=1.083, 95% CI=0.930-1.260, p=0.307). However, stratification by ethnicity indicated an association between the IL-18 -607 C allele and T1D in Asians (OR=1.506, 95% CI=1.172-1.936, p=0.001), but not in Europeans (OR=0.988, 95% CI=0.808-1.209, p=0.907). Analysis using recessive and dominant models and homozygote contrast showed the same -607 C allele pattern in Asians and Europeans. Meta-analysis of the IL-18 -137 G/C polymorphism showed no association between T1D and the IL-18 -137 G allele in all study subjects (OR=1.066, 95% CI=0.926-1.2289, p=0.375). Stratification by ethnicity indicated no association between the IL-18 -137 G allele and T1D in Europeans and Asians (OR=1.021, 95% CI=0.961-1.085, p=0.504; OR=0.851, 95% CI=0.5821-1.245, p=0.406).

CONCLUSIONS

Our meta-analysis demonstrates that the IL-18 -607 C/A polymorphism may be associated with susceptibility to T1D in Asians, but not in Europeans.

Elevated levels of serum IL-12 and IL-18 are associated with lower frequencies of CD4(+)CD25 (high)FOXP3 (+) regulatory t cells in young patients with type 1 diabetes

Type 1 diabetes is thought to involve chronic inflammation, which is manifested by the activation and expression of different inflammatory mediators. IL-12 and IL-18 are two cytokines that have been shown to exert strong proinflammatory activity and have been implicated in the pathogenesis of type 1 diabetes in mice and humans. The overproduction of proinflammatory mediators is controlled by specialized T cell subset, namely regulatory T cells that express FOXP3 transcription factor. Since IL-12 and IL-18 mediate inflammatory response and Tregs exhibit anti-inflammatory potential, we aimed to examine their reciprocal relationship in patients with type 1 diabetes. The study group consisted of 47 children diagnosed with type 1 diabetes and 28 healthy individuals. Serum levels of IL-12 and IL-18 were measured by ELISA, and the peripheral blood CD4⁺CD25^high FOXP3⁺ regulatory T cell frequencies were analyzed by flow cytometry. Patients with type 1 diabetes had a decreased percentage of circulating CD4⁺CD25^highFOXP3⁺ Tregs in comparison to their healthy counterparts. In addition, they produced more IL-12 and IL-18 than children from the control group. Concentrations of these cytokines positively correlated with one another, as well as with CRP and HbA1c. Moreover, the negative association between IL-12, IL-18, CRP serum levels, and the frequency of regulatory CD4⁺CD25^highFOXP3⁺ Tregs was observed. IL-12 and IL-18 may have direct or indirect impact on regulatory T cell subset, which may contribute to their reduced frequency in peripheral blood of patients with type 1 diabetes mellitus.

Evaluation of Hs-CRP levels and interleukin 18 (-137G/C) promoter polymorphism in risk prediction of coronary artery disease in first degree relatives

BACKGROUND

Coronary Artery Disease (CAD) is clearly a multifactorial disease that develops from childhood and ultimately leads to death. Several reports revealed having a First Degree Relatives (FDRS) with premature CAD is a significant autonomous risk factor for CAD development. C - reactive protein (CRP) is a member of the pentraxin family and is the most widely studied proinflammatory biomarker. IL-18 is a pleiotrophic and proinflammatory cytokine which is produced mainly by macrophages and plays an important role in the inflammatory cascade.

METHODS AND RESULTS

Hs-CRP levels were estimated by ELISA and Genotyping of IL-18 gene variant located on promoter -137 (G/C) by Allele specific PCR in blood samples of 300 CAD patients and 300 controls and 100 FDRS. Promoter Binding sites and Protein interacting partners were identified by Alibaba 2.1 and Genemania online tools respectively. Hs-CRP levels were significantly high in CAD patients followed by FDRS when compared to controls. In IL-18 -137 (G/C) polymorphism homozygous GG is significantly associated with occurrence of CAD and Hs-CRP levels were significantly higher in GG genotype subjects when compared to GC and CC. IL-18 was found to be interacting with 100 protein interactants.

CONCLUSION

Our results indicate that Hs-CRP levels and IL-18-137(G/C) polymorphism may help to identify risk of future events of CAD in asymptomatic healthy FDRS.

Predictive potential of IL-18 -607 and osteopontin -442 polymorphism in interferon-based therapy of HCV infection in the Pakistani population

The adaptive immune system plays an important role in response to interferon plus ribavirin treatment of hepatitis C virus (HCV) infection. Cytokines play a significant role in the adaptive immune system. The production of cytokines may be regulated by single nucleotide polymorphisms (SNPs). This study was designed to examine the correlation of some important SNPs of cytokines with interferon plus ribavirin treatment of HCV infection in the Pakistani population. We followed 140 chronic HCV-infected patients in our study. All of these patients had completed their planned course of interferon plus ribavirin treatment. We also considered 120 healthy subjects as controls. The detection of interleukin-18 (IL-18) SNPs was performed by tetra-primers amplification-refectory mutation system polymerase chain reaction, while for genotyping of osteopontin (OPN), transforming growth factor beta (TGFβ), and N-acetylgalactosaminyltransferase 8 (GALNT8) SNPs, allele-specific polymerase chain reaction was performed. The distribution of the IL-18 -607AA genotype varied significantly between healthy control and patient groups. Its distribution was significantly high in healthy subjects than HCV patients (p = 0.031), signifying its potential involvement in the natural clearance of HCV infection. The occurrence of the -607AA genotype of IL-18 was also significantly higher in the sustained virological group (SVR) than in the nonresponder (NR) group (p = 0.046), highlighting its protective involvement in the treatment outcome of chronic HCV infection. The frequency of the OPN -442TT genotype was higher in the SVR group than in the NR group (p = 0.034), indicating a significant possible role of this genotype in therapy for HCV infection. No important association was found between TGFβ and GALNT8 genotypes and the natural clearance and treatment response of HCV infection. IL-18 -607AA and OPN -442TT genotypes can be used as positive predictive markers of interferon plus ribavirin treatment of HCV infection in the Pakistani population.

Association of IL-18 promoter gene polymorphisms with rheumatoid arthritis: a meta-analysis

Interleukin-18(IL-18) plays a potential pathological role in rheumatoid arthritis (RA). The conclusions of the published reports on the relationship between single-nucleotide polymorphisms -607C/A (rs1946518) and -137G/C (rs187238) located in the IL-18 gene promoter and RA risk remain controversial. This meta-analysis was performed to evaluate the association between IL-18 gene promoter (-607A/C and -137C/G) polymorphisms and RA using (1) allele, (2) codominant, (3) dominant, and (4) recessive models. Literature search was conducted up to January, 2013, in PubMed, EMBASE, Spring-link, Web of Science, Wanfang (Chinese) and China National Knowledge Infrastructure (CNKI). A total of 10 studies from eight articles involving 2,662 cases and 2,168 controls for -607A/C polymorphism and 9 studies from six articles involving 1,331 cases and 1,468 controls for -137C/G polymorphism were considered in the meta-analysis. For the relationship of IL-18 -607A/C polymorphism with RA risk, significant association was observed in allele model (OR = 0.778, 95 % CI = 0.633-0.955) and dominant model (OR = 0.618, 95 % CI = 0.466-0.819). However, no significant association could be observed between -137C/G polymorphism and RA risk under all genetic models (allele model: OR = 0.940, 95 % CI = 0.777-1.138; codominant model: OR = 1.079, 95 % CI = 0.574-2.029; dominant model: OR = 0.913, 95 % CI = 0.779-1.069; recessive model: OR = 1.133, 95 % CI = 0.586-2.190). In the subgroup analysis by ethnicity, significant result was also found in Asian populations but not found in Caucasian populations for the relationship of IL-18 -607A/C polymorphism with RA risk; while no obvious association was found between IL-18 -137C/G polymorphism and RA risk. This meta-analysis indicates that IL-18 -607A/C polymorphism in promoter region may be associated with RA risk.

Association of the interleukin-18 -137 C/G, -607 A/C polymorphisms with type 1 diabetes: A meta-analysis

Published data on the association between interleukin (IL)-18 gene polymorphisms (-137 C/G, -607 A/C) and type 1 diabetes (T1D) risk are inconclusive. To obtain a more precise estimation of the association between the IL-18 gene polymorphisms and T1D, a meta-analysis was performed. A total of 11 studies including 5,945 cases and 6,404 controls were included in the analysis of the association between -137 C/G and T1D risk. No significant association between -137 C/G and T1D risk was observed in the total population [C vs. G: odds ratio (OR)=1.02, 95% confidence interval (CI)=0.87-1.20; CC + CG vs. GG: OR=1.05, 95% CI=0.87-1.25; CC vs. CG + GG: OR=0.96, 95% CI=0.68-1.36]. No significant association was identified in the stratified analysis for all the genetic models in the European population. Concerning -607 A/C, 10 studies involving 3,048 patients and 3,377 controls were included in this meta-analysis. When all the studies were pooled, the results showed no evidence for a significant association between IL-18 -607 A/C polymorphism and T1D risk (A vs. C: OR=0.93, 95% CI=0.81-1.06; AA + AC vs. CC: OR=0.99, 95% CI=0.89-1.10; AA vs. AC + CC: OR=0.81, 95% CI=0.60-1.09). In addition, similar results were obtained in the subgroup analysis based on ethnicity. In summary, the present meta-analysis suggests a lack of association between the two polymorphisms (-137 C/G, -607 A/C) in the IL-18 gene and T1D. Due to the limitation of the number of the studies, the conclusions drawn should be considered with caution. Larger scale primary studies are required to evaluate the association between IL-18 gene polymorphisms and T1D.

Effector and regulatory T cell subsets in diabetes-associated inflammation. Is there a connection with ST2/IL-33 axis? Perspective

Type 1 diabetes (DM1) is a chronic inflammatory disease, which when progresses leads to the development of late vascular complications. The disease involves impairments in regulatory and effector subsets of T lymphocytes, which suppress and maintain inflammatory response, respectively. ST2/IL-33 pathway is involved in T-cell-mediated immune response and might regulate the inflammatory process in several diseases. This review presents the latest research findings regarding effector and regulatory T cell subsets in the context of inflammation accompanying DM1 with particular focus on the ST2/IL-33 network and its possible association with T cell-mediated immunity.

IL-18 in inflammatory and autoimmune disease

Inflammation serves as the first line of defense in response to tissue injury, guiding the immune system to ensure preservation of the host. The inflammatory response can be divided into a quick initial phase mediated mainly by innate immune cells including neutrophils and macrophages, followed by a late phase that is dominated by lymphocytes. Early in the new millennium, a key component of the inflammatory reaction was discovered with the identification of a number of cytosolic sensor proteins (Nod-like receptors) that assembled into a common structure, the 'inflammasome'. This structure includes an enzyme, caspase-1, which upon activation cleaves pro-forms of cytokines leading to subsequent release of active IL-1 and IL-18. This review focuses on the role of IL-18 in inflammatory responses with emphasis on autoimmune diseases.

Interleukin-18 Promoter Gene Polymorphisms are not Associated with Myocardial Infarction in Type 2 Diabetes in Slovenia

Type 2 diabetes is a major risk factor for myocardial infarction (MI) and chronic inflammation may play a central role in both diseases. Interleukin (IL)-18 is a potent proinflammatory cytokine, which is considered important in acute coronary syndromes and type 2 diabetes. We investigated the association of the −137 (G>C), polymorphism (rs187238) and the −607 (C>A) polymorphism (rs1946518) of the IL-18 gene promoter region in 495 Caucasians with type 2 diabetes, of whom 169 had MI and 326 subjects had no clinically evident coronary artery disease (controls). We also investigated the impact of these polymorphisms on the serum IL-18 level in subsets of both groups and in a normal group. Genotype distributions of the polymorphisms showed no significant difference between cases and controls. However, IL-18 serum levels were significantly lower in diabetics with the 137 CC genotype than in those with other genotypes (241.5 ± 132.7 ng/L vs. 340.2 ± 167.4 ng/L; p <0.05). High sensitivity C-reactive protein and IL-18 serum levels were higher in diabetics in the MI group than in the control group. We conclude that these IL-18 promoter gene polymorphisms are not risk factors for MI in Caucasians with type 2 diabetes.

Association of interleukin-18 gene polymorphisms with the outcomes of hepatitis C virus infection in high-risk Chinese Han population

Interleukin 18 (IL-18) gene polymorphisms have been reported to be associated with the outcomes of hepatitis C virus (HCV) infection in Americans, Indians and Europeans. We aimed to investigate whether the association can be replicated in Chinese Han population. Three IL-18 variants, -656G>T, -137G>C and +105A>C, were genotyped in three independent Han cohorts consisting of 552 cases and 784 controls. By using logistic regression analysis and multiple testing, haplotype GCC were associated with a protection from susceptibility to HCV. After stratified analysis, both the carriage of -137C allele in the older or hemodialysis subgroup and the carriage of +105C allele in the younger subgroup were found to be significantly associated with a decreased risk of HCV susceptibility. By using logistic regression analysis and multiple testing for the resolution of HCV infection, our study showed that +105C allele and haplotype GGC displayed a negative effect on HCV persistence. After stratified analysis, a significantly decreased risk for HCV persistence was found in +105C allele in the subgroups of young, male or female, drug user or hemodialysis and HCV-1 or HCV mixed genotype. No significant association was observed between -656G>T and the outcomes of HCV infection. Our results demonstrated that the carriage of -137C allele, +105C allele, haplotype -656G/-137C/+105C and haplotype -656G/-137G/+105C of IL-18 gene may contribute to better outcomes of HCV infection in high-risk Chinese Han population.

Polymorphisms in the IL-18 and IL-12B genes and their association with the clinical outcome in Croatian patients with Type 1 diabetes

Genetic variants of IL-18 and IL-12B may be important in immunoregulatory abnormalities, observed in the patients with Type 1 diabetes mellitus (T1DM), that contribute to individual differences in response to a treatment. Therefore, we examined the significance of IL-18-137G/C, IL-18-607C/A, and IL-12B A/C polymorphisms in Croatians (187 patients, 236 controls), not only as factors that contribute to susceptibility to T1DM, but also as determinants of the clinical presentation of disease. The polymorphism screening has been performed using PCR sequence-specific primers (IL-18) or PCR-RFLP (IL-12B) approach. Results were evaluated by GraphPad Prism and Sigma Stat 3.5, Arlequin software and calculator for Hardy-Weinberg equilibrium. The genotype, allele and haplotype distribution were not statistically different between the patients and control subjects. The clinical parameter analysis revealed that patients with minor alleles at each locus, IL-18-137C/-607A, were significantly younger at T1DM onset than carriers of major alleles, IL-18-137G/-607C (20 vs 23.5 years). Moreover, the concomitant presence of minor alleles not only of IL-18 but also of IL-12B, is associated with the risk of disease progression even at younger age. These patients developed diabetes at 16 years of age, what is significantly earlier (p=0.044) compared to 25.5 years of age in patients with common alleles IL-18-137G/-607C/IL-12B A. Furthermore, combined genotype analysis of IL-18 and IL-12B has pointed out that patients with CC/AA/AA genotype have the worst glucose control based on HbA1c (8.7%, range 6.8-13.1%). In conclusion, susceptibility to T1DM in Croatians is not strongly associated with IL-18-137/-607 and IL-12B polymorphisms. These SNPs are associated with the higher risk of earlier disease development and might be implicated in the effectiveness of glycemic control.

The IL18 gene and Hashimoto thyroiditis in children

Interleukin 18 (IL18) stimulates interferon-γ production in Th1 cells which are prominent in the thyroid of Hashimoto thyroiditis (HT). We investigated the association between the IL18 gene and HT. There were 116 children with HT and 1272 controls. rs187238 and rs1946518 in the promoter region of the IL18 gene were genotyped. Differences in genotype, allele, carrier, and haplotype distributions between patients and controls were compared. A Pc value <0.05 was considered significant. The frequency of the C/G genotype of rs187238 was significantly higher in patients and conferred a risk of HT (OR, 1.96; 95% CI, 1.30-2.95; Pc, 0.0021). So did the frequencies of allele C (OR, 1.73; 95% CI, 1.22-2.44; Pc, 0.0035) and carrier C (OR, 1.96; 95% CI, 1.31-2.92; Pc, 0.0017), however the frequency of the G/G genotype was significantly lower in patients than in controls (OR, 0.51; 95% CI, 0.34-0.76; Pc, 0.0034). There was no association between HT and rs1946518. The CT haplotype was significantly more frequent in patients than in controls and conferred a risk of HT (OR, 1.76; 95% CI, 1.24-2.49; Pc, 0.0049). We concluded that the IL18 gene was associated with HT in children. The rs187238C allele and CT haplotype conferred a risk of HT.

Lack of association of interleukin-18 gene promoter -607 A/C polymorphism with susceptibility to autoimmune diseases: a meta-analysis

OBJECTIVE

Published data on the association between interleukin (IL)-18 gene promoter -607 A/C polymorphism and autoimmune diseases risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed.

METHODS

A total of 17 studies, including six studies on type 1 diabetes (T1D), four on rheumatoid arthritis (RA), five on systemic lupus erythematosus (SLE), three on Crohn's Disease (CD) and three on ulcerative colitis (UC), were available for the meta-analysis. Meta-analysis was performed for genotypes A/A (recessive effect), genotypes A/A + A/C (dominant effect), and A allele in fixed or random-effects models.

RESULTS

Overall, no significantly elevated autoimmune diseases risk was found in all genetic models when all studies were pooled into the meta-analysis. The overall odds ratios (ORs) and 95% confidence intervals (CIs) for A-allele were T1D (OR = 0.938, 95% CI = 0.757-1.162), RA (OR = 0.759, 95% CI = 0.540-1.067), SLE (OR = 0.858, 95% CI = 0.609-1.208), CD (OR = 1.159, 95% CI = 0.975-1.379) and UC (OR = 1.170, 95% CI = 0.977-1.402), respectively. In the subgroup analysis by ethnicity, there was still no significant association detected in all genetic models.

CONCLUSIONS

To date, there is still not enough evidence to indicate the association of IL-18 gene promoter -607 A/C polymorphism and the development of autoimmune diseases.

Cytokine and apoptosis gene polymorphisms influence the outcome of hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) infection is thought to be chronic and the factors leading to viral clearance or persistence are poorly understood. This study was undertaken to investigate the possibility of a significant relationship between the spontaneous clearance or the persistence of hepatitis C virus (HCV) infection and cytokine and apoptosis gene polymorphisms in Tunisian patients on hemodialysis.

METHODS

Polymorphisms of the genes IL-1 (-889 IL-1alpha, -511 and +3954 IL-1beta, IL-1Ra), IL-18 (-137 and -607), IL-12 (-1188) and Apo1/Fas (-670) were determined by PCR-RFLP, PCR-SSP and PCR-VNTR in 100 healthy blood donors and 100 patients infected with HCV and undergoing hemodialysis. The patients were classified into two groups: G1 consisted of 76 active chronic hepatitis patients (positive for HCV RNA) and G2 consisted of 24 hemodialysed patients who spontaneously eliminated the virus (negative for HCV RNA).

RESULTS

The frequency of genotype association [-137GC/-607CA] IL-18 was higher in G2 (41.7%) than in G1 (15.8%) (P=0.008; OR=0.26; 95% CI, 0.10-0.73). We also found a higher frequency of the AA genotype of the Apo1/Fas gene in G2 (41.6%) than in G1 (17.5%) (P=0.026; OR=3.49; 95% CI, 1.13-10.69). Adjustment for known covariate factors (age, gender and genotype) confirmed these univariate findings and revealed that the genotype association GC-CA of the (-137 and -607) IL-18 gene and the AA genotype of the Apo1/Fas gene were associated with the clearance of HCV (P=0.041 and 0.017, respectively).

CONCLUSION

The two genotypes GC-CA of the (-137 and -607) IL-18 polymorphism and the AA genotype of the Apo1/Fas gene influence the outcome of HCV infection in Tunisian patients on hemodialysis.

Lack of association of -607 C/A and -137 G/C polymorphisms in interleukin 18 gene with susceptibility to gout disease in Chinese Han male population

To identify association of IL18-607 C/A and -137 G/C polymorphism with susceptibility to gout in Chinese Han male population, We evaluate the genetic contribution of the IL18-607 C/A and -137 G/C polymorphism in 202 gout male patients and 493 gout-free control of Chinese Han population by allele-specific polymerase chain reaction assay. Our results reveal no significant association between the polymorphisms -607C/A and -137G/C in IL18 with gout. Our study might suggest that -607 C/A and -137 G/C polymorphisms in the promoter of IL18 are not associated with susceptibility to gout and thus do not play a major role in the development of gout in the Chinese Han male population.

Dense mapping of IL18 shows no association in SLE

Systemic lupus erythematosus (SLE) is an autoimmune disease which behaves as a complex genetic trait. At least 20 SLE risk susceptibility loci have been mapped using both candidate gene and genome-wide association strategies. The gene encoding the pro-inflammatory cytokine, IL18, has been reported as a candidate gene showing an association with SLE. This pleiotropic cytokine is expressed in a range of immune cells and has been shown to induce interferon-γ and tumour necrosis factor-α. Serum interleukin-18 has been reported to be elevated in patients with SLE. Here we aimed to densely map single nucleotide polymorphisms (SNPs) across IL18 to investigate the association across this locus. We genotyped 36 across IL18 by Illumina bead express in 372 UK SLE trios. We also genotyped these SNPs in a further 508 non-trio UK cases and were able to accurately impute a dense marker set across IL18 in WTCCC2 controls with a total of 258 SNPs. To improve the study's power, we also imputed a total of 158 SNPs across the IL18 locus using data from an SLE genome-wide association study and performed association testing. In total, we analysed 1818 cases and 10 770 controls in this study. Our large well-powered study (98% to detect odds ratio = 1.5, with respect to rs360719) showed that no individual SNP or haplotype was associated with SLE in any of the cohorts studied. We conclude that we were unable to replicate the SLE association with rs360719 located upstream of IL18. No evidence for association with any other common variant at IL18 with SLE was found.

Association of polymorphisms of interleukin-18 gene promoter region with polycystic ovary syndrome in chinese population

BACKGROUND

Recent research shows that polycystic ovary syndrome (PCOS) may have an association with low-grade chronic inflammation, and that PCOS may induce an increase in serum interleukin-18 (IL-18) levels.

METHODS

To investigate the polymorphisms of the IL-18 gene promoters with PCOS, two single nucleotide polymorphisms (SNPs) in the promoter of the IL-18 gene (at positions -607C/A and -137G/C) in 118 Chinese women with PCOS and 79 controls were evaluated using polymerase chain reaction (PCR).

RESULTS

No significant differences were found in the genotype distribution, allele frequency and haplotype frequency between the PCOS and control groups. Further analysis demonstrated a relationship between IL-18 gene promoter polymorphisms and PCOS insulin resistance (IR). Regarding the -137 allele frequency, G and C allele frequencies were 93.5% and 6.5%, respectively, in the PCOS with IR patients; G and C allele frequencies were 85.4% and 14.6%, respectively, in PCOS patients without IR (chi2 = 3.601, P = 0.048).

CONCLUSIONS

The presence of a polymorphism in the IL-18 gene was found to have no correlation with the occurrence of PCOS. Carriage of the C allele at position -137 in the promoter of the IL-18 gene may play a protective role from the development of PCOS IR.

Association of polymorphisms in the IL-18 and IL-12 genes with susceptibility to Type 1 diabetes in Turkish patients

BACKGROUND

Recent studies have indicated that polymorphisms of the interleukin-18 (IL-18) and interleukin- 12 (IL-12) genes are associated with the development of Type 1 diabetes mellitus (T1DM) in some populations, but not all.

AIM

The present study was designed to examine the roles of polymorphisms in the IL-18 promoter and IL-12p40 with respect to susceptibility to T1DM in Turkish patients.

SUBJECTS AND METHODS

Ninety-one patients with T1DM and 87 unrelated healthy subjects were included in the study. The IL-18 polymorphisms at positions -607 and -137 were detected by a sequence-specific PCR method. The single nucleotide polymorphism in the IL-12p40 3' untranslated region (3'-UTR) at position +1188 was analyzed by the PCR-restriction fragment length polymorphism (RFPL) method.

RESULTS

The allelic and genotypic frequencies of the IL-18 and IL-12p40 polymorphisms did not differ significantly between subjects with T1DM and the controls (p>0.05). However, diabetic patients with the -137 (CC) genotype showed a younger onset age compared to patients with the -137 (GG) genotype (p=0.02). In addition, patients with the -607 (CC) genotype had higher levels of glycated hemoglobin (HbA1c) than patients with the -607 (AC) genotype (p=0.004). Furthermore, patients with the IL-12p40 (AC) genotype had higher HbA(1c) levels than patients with the IL-12p40 (AA) genotype (p=0.01).

CONCLUSIONS

The results of the present study show that the IL- 18 and IL-12p40 polymorphisms may have some effect on the onset age and deterioration of glycemic control in Turkish patients with T1DM.

-607 C/A polymorphism in the promoter of IL-18 gene is associated with 2 h post-loading plasma glucose level in Chinese

The purpose of this study is to find out whether the -607 C/A polymorphism in IL-18 gene promoter will affect serum IL-18 concentrations and glucose metabolism in Chinese subjects. In 232 patients with impaired glucose regulation (IGR) or type 2 diabetes and 212 subjects of normal glucose regulation (NGR), -607 C/A polymorphism was analyzed by polymerase chain reaction with sequence specific primers. Serum IL-18 concentrations were determined by ELISA in 200 subjects. Compared with subjects with NGR, those with type 2 diabetes and IGR had significant higher IL-18 concentrations [114.4 (92.9-149.2) and 102.1 (67.5-138.2) vs. 77.3 (53.8-107.8) pg/ml, P = 0.0026 and P < 0.0001, respectively]. A significantly higher proportion of A/A genotype of -607 C/A polymorphism presented in patients with type 2 diabetes compared with subjects of NGR (23.8% vs. 10.9%, P = 0.005). Subjects with an A/A genotype also had higher 2 h post-loading plasma glucose (2 h-PPG) compared with C/A and C/C genotypes even after adjustments of age, sex and BMI [8.94 (7.55-12.3) vs. 7.80 (6.00-9.87) and 7.23 (5.66-8.99) mmol/l, P both < 0.05]. Multiple linear regression revealed that BMI (P < 0.0001) and 2 h-PPG (P = 0.019) were independently associated with IL-18 concentrations. In conclusion, subjects with IGR or type 2 diabetes had significantly higher concentrations of IL-18 than those with NGR. Genotype A/A of IL-18 gene promoter -607 C/A polymorphism was associated with higher prevalence of type 2 diabetes and 2 h post-loading plasma glucose level.

Evaluation of 6 candidate genes on chromosome 11q23 for coeliac disease susceptibility: a case control study

Background

Recent whole genome analysis and follow-up studies have identified many new risk variants for coeliac disease (CD, gluten intolerance). The majority of newly associated regions encode candidate genes with a clear functional role in T-cell regulation. Furthermore, the newly discovered risk loci, together with the well established HLA locus, account for less than 50% of the heritability of CD, suggesting that numerous additional loci remain undiscovered. Linkage studies have identified some well-replicated risk regions, most notably chromosome 5q31 and 11q23.

Methods

We have evaluated six candidate genes in one of these regions (11q23), namely CD3E, CD3D, CD3G, IL10RA, THY1 and IL18, as risk factors for CD using a 2-phase candidate gene approach directed at chromosome 11q. 377 CD cases and 349 ethnically matched controls were used in the initial screening, followed by an extended sample of 171 additional coeliac cases and 536 additional controls.

Results

Promotor SNPs (-607, -137) in the IL18 gene, which has shown association with several autoimmune diseases, initially suggested association with CD (P < 0.05). Follow-up analyses of an extended sample supported the same, moderate effect (P < 0.05) for one of these. Haplotype analysis of IL18-137/-607 also supported this effect, primarily due to one relatively rare haplotype IL18-607C/-137C (P < 0.0001), which was independently associated in two case-control comparisons. This same haplotype has been noted in rheumatoid arthritis.

Conclusion

Haplotypes of the IL18 promotor region may contribute to CD risk, consistent with this cytokine's role in maintaining inflammation in active CD.

Association between IL-18 gene polymorphisms and biopsy-proven giant cell arteritis

INTRODUCTION

The objective was to investigate the potential implication of the IL18 gene promoter polymorphisms in the susceptibility to giant-cell arteritis (GCA).

METHODS

In total, 212 patients diagnosed with biopsy-proven GCA were included in this study. DNA from patients and matched controls was obtained from peripheral blood. Samples were genotyped for the IL18-137 G>C (rs187238), the IL18-607 C>A (rs1946518), and the IL18-1297 T>C (rs360719) gene polymorphisms with polymerase chain reaction, by using a predesigned TaqMan allele discrimination assay.

RESULTS

No significant association between the IL18-137 G>C polymorphism and GCA was found. However, the IL18 -607 allele A was significantly increased in GCA patients compared with controls (47.8% versus 40.9% in patients and controls respectively; P = 0.02; OR, 1.32; 95% CI, 1.04 to 1.69). It was due to an increased frequency of homozygosity for the IL18 -607 A/A genotype in patients with GCA (20.4%) compared with controls (13.4%) (IL18 -607 A/A versus IL18 -607 A/C plus IL18 -607 C/C genotypes: P = 0.04; OR, 1.59; 95% CI, 1.02 to 2.46). Also, the IL18-1297 allele C was significantly increased in GCA patients (30.7%) compared with controls (23.0%) (P = 0.003; OR, 1.48; 95% CI, 1.13 to 1.95). In this regard, an increased susceptibility to GCA was observed in individuals carrying the IL18-1297 C/C or the IL18-1297 C/T genotypes compared with those carrying the IL18-1297 T/T genotype (IL18-1297 C/C plus IL18-1297 T/C versus IL18-1297 T/T genotype in GCA patients compared with controls: P = 0.005; OR, 1.61; 95% CI, 1.15 to 2.25). We also found an additive effect of the IL18 -1297 and -607 polymorphisms with TLR4 Asp299Gly polymorphism. The OR for GCA was 1.95 for combinations of genotypes with one or two risk alleles, whereas carriers of three or more risk alleles have an OR of 3.7.

CONCLUSIONS

Our results show for the first time an implication of IL18 gene-promoter polymorphisms in the susceptibility to biopsy-proven GCA. In addition, an additive effect between the associated IL18 and TLR4 genetic variants was observed.

Genetic variants in immunoregulatory genes and risk for childhood lymphomas

To investigate whether single nucleotide polymorphisms (SNPs) in key cytokine and innate immunity genes influence risk for childhood lymphomas, we genotyped 37 children with Hodgkin's (HL) and 48 with non-Hodgkin's lymphoma (NHL), aged (1 month-14 yr), along with their 85 age- and gender-matched controls suffering from mild medical conditions. Genotypic analysis was performed for 10 SNPs from nine genes with important role in immunoregulatory pathways (IL4, IL4R, IL6, IL10, IL12, IL18, TNFalpha, IFNgamma, CD14). Analysis of SNPs genotypes revealed that the CD14 -159 C>T polymorphism was associated with significantly increased risk for HL regarding both the CC and CT genotypes (OR(CC): 5.36; 95% CI, 1.30-22.14; P = 0.02, OR(CT): 3.76; 95% CI, 1.00-14.16; P = 0.05). An indicative association between IL18-137 G>C polymorphism with the CC genotype and NHL did not reach, however, statistical significance (OR(CC), 3.78; 95% CI, 0.87-16.38; P = 0.08). In conclusion, our findings suggest that genetic variation in the CD14-159 loci may be associated with childhood HL risk; these preliminary findings need to be further confirmed in sizeable multi-centre studies along with determination of cytokines, which could provide an insight on the biologic basis underlying these findings.

Interleukin-18 gene 105A/C genetic polymorphism is associated with the susceptibility of Kawasaki disease

Interleukin-18 (IL-18)-656T/G, -607A/C, and -137C/G promoter polymorphisms had been reported associated with Kawasaki disease (KD). An IL-18 genetic A/C polymorphism at coding position 105 (rs549908) has been linked with asthma, rheumatoid, and systemic lupus erythematosus. We tested a hypothesis that the IL-18 105A/C genetic polymorphism confers KD susceptibility. Study participants were Taiwanese KD patients and a healthy control group. Our data indicated that the frequency of C allele was significantly higher in the patient group (13.9%) than in the control group (2.7%; P<0.0001, odds ratio [OR]=5.93; 95% confidence interval [CI]=2.57-13.73). Therefore, persons with the C allele may have higher risk of developing KD. In addition, compared with the haplotype frequencies between case and control groups, the KD patients with TACC haplotype appeared to be a significant "at-risk" haplotype compared with other haplotypes (OR: 4.62, 95% CI: 1.71-12.43; P=0.001). KD patient with the TAGA haplotype appeared to be a significant "protective" haplotype compared with other haplotypes (OR: 0.51, 95% CI:0.29-0.89; P=0.017). Our results suggest that 105A/C polymorphism and the haplotypes in IL-18 gene are associated with the risk of KD in Taiwanese population.

Novel polymorphism of interleukin-18 associated with greater inflammation after cardiac surgery

Introduction

Interleukin (IL)-18 is a key modulator of the cytokine response that leads to organ dysfunction and prolonged intensive care unit (ICU) stay after cardiopulmonary bypass surgery. We hypothesised that variation in the pro-inflammatory gene IL-18 is associated with adverse clinical outcome because of a more intense inflammatory response.

Methods

Haplotypes of the IL-18 gene were inferred from genotypes of 23 Coriell Registry subjects. Four haplotype tag single nucleotide polymorphisms (-607 C/A, -137 G/C, 8148 C/T and 9545 T/G) identified four major haplotype clades. These polymorphisms were genotyped in 658 Caucasian patients undergoing cardiopulmonary bypass surgery. Clinical phenotypes were collected by retrospective chart review.

Results

Patients homozygous for the T allele of the 9545 T/G polymorphism had an increased occurrence of prolonged ICU stay (6.8% for TT genotype versus 2.7% for GG or GT genotype; p = 0.015). Patients homozygous for the T allele also had increased occurrence of low systemic vascular resistance index (62%) compared with the GG and GT genotypes (53%; p = 0.045). Patients homozygous for the T allele had increased serum IL-18 concentrations 24 hours post-surgery (p = 0.018), increased pro-inflammatory tumour necrosis factor alpha concentrations (p = 0.014) and decreased anti-inflammatory serum IL-10 concentrations (p = 0.018) 24 hours post-surgery.

Conclusions

The TT genotype of the IL-18 9545 T/G polymorphism is associated with an increased occurrence of prolonged ICU stay post-surgery and greater post-surgical inflammation. These results may be explained by greater serum IL-18, leading to greater pro-versus anti-inflammatory cytokine expression.

T cell cytokine gene polymorphisms in canine diabetes mellitus

Insulin-deficiency diabetes in dogs shares some similarities with human latent autoimmune diabetes of adults (LADA). Canine diabetes is likely to have a complex pathogenesis with multiple genes contributing to overall susceptibility and/or disease progression. An association has previously been shown between canine diabetes and MHC class II genes, although other genes are also likely to contribute to the genetic risk. Potential diabetes susceptibility genes include immuno-regulatory TH1/TH2 cytokines such as IFNgamma, IL-12, IL-4 and IL-10. We screened these candidate genes for single nucleotide polymorphisms (SNPs) in a range of different dog breeds using dHPLC analysis and DNA sequencing. Thirty-eight of the SNPs were genotyped in crossbreed dogs and seven other breed groups (Labrador Retriever, West Highland White Terrier, Collie, Schnauzer, Cairn Terrier, Samoyed and Cavalier King Charles Spaniel), which demonstrated substantial intra-breed differences in allele frequencies. When SNPs were examined for an association with diabetes by case:control analysis significant associations were observed for IL-4 in three breeds, the Collie, Cairn Terrier and Schnauzer and for IL-10 in the Cavalier King Charles Spaniel. These results suggest that canine cytokine genes regulating the TH1/TH2 immune balance might play a contributory role in determining susceptibility to diabetes in some breeds.

Levels of interleukin-18 are markedly increased in Helicobacter pylori-infected gastric mucosa among patients with specific IL18 genotypes

BACKGROUND

The cellular immune response in gastric mucosa infected with Helicobacter pylori is proposed to be predominantly of the T helper cell type 1 type.

METHODS

Interleukin (IL)-18, IL-12, and interferon (IFN)-gamma levels were measured in gastric mucosal biopsy specimens by reverse-transcription polymerase chain reaction (PCR) and by enzyme-linked immunosorbent assay; IL18 polymorphisms were determined by PCR.

RESULTS

Biopsy specimens from 128 patients (56 with nonulcer dyspepsia, 28 with gastric ulcers, 28 with duodenal ulcers, and 16 with gastric cancer) were examined; 96 patients had H. pylori infection. IL-18 levels were markedly up-regulated in mucosa infected with H. pylori (P < .001), whereas IL-12 and IFN-gamma levels were independent of H. pylori status. IL-18 levels correlated with IFN-gamma levels only in infected patients (R = 0.31 to R = 0.51). IL-18 levels were the determining factor for monocyte infiltration in H. pylori-infected mucosa (P < .001). H. pylori-infected patients displaying IL18 -607C/C and -137G/G had higher IL-18 levels than did those with other genotypes and were more likely to experience treatment failure.

CONCLUSION

H. pylori infection induces IL-18 in the gastric mucosa. H. pylori-infected patients with IL18 -607C/C and -137G/G have higher IL-18 levels, which causes severe gastric inflammation. IL18 genotype might be a marker for predicting the effects of eradication therapy.