Interleukin-18 genetics and inflammatory disease susceptibility

Association of carotid atheroma plaque with IL-18 levels and with polymorphisms in the IL-18 receptor gene in a Mediterranean population

BACKGROUND

Atherosclerosis is an inflammatory disease. Interleukin 18 (IL-18) is an inflammatory molecule that has been linked to the development of atherosclerosis and cardiovascular disease.

OBJECTIVE

To evaluate the possible relationship between plasma levels of IL-18 and the presence of atherosclerosis evaluated at the carotid level, as well as to analyze the possible modulation by different polymorphisms in a Mediterranean population.

MATERIAL AND METHODS

Seven hundred and forty-six individuals from the metropolitan area of Valencia were included, recruited over a period of 2 years. Hydrocarbon and lipid metabolism parameters were determined using standard methodology and IL-18 using ELISA. In addition, carotid ultrasound was performed and the genotype of four SNPs related to the IL-18 signaling pathway was analyzed.

RESULTS

Patients with higher plasma levels of IL-18 had other associated cardiovascular risk factors. Elevated IL-18 levels were significantly associated with higher carotid IMT and the presence of atheromatous plaques. The genotype with the A allele of the SNP rs2287037 was associated with a higher prevalence of carotid atheromatous plaque. On the contrary, the genotype with the C allele of the SNP rs2293224 was associated with a lower prevalence of atheromatous plaque.

CONCLUSIONS

High levels of IL-18 were significantly associated with a higher carotid IMT and the presence of atheromatous plaques, which appear to be influenced by genetic factors, as evidenced by associations between SNPs in the IL-18 receptor gene and the presence of atheroma plaque.

The immunotoxicity of decabromodiphenyl ether (BDE-209) on broiler chicks by transcriptome profiling analysis

Decabromodiphenyl ether (BDE-209) has drawn significant attention due to its suppression of immune functions in animals and even humans. In order to explore the mechanism through which BDE-209 affects the immune system, broiler chicks were fed a diet containing various concentrations of BDE-209 (0, 0.004, 0.04, 0.4, and 4 g/kg) for 42 days. Histopathological observations of immune organs found damaged and necrotic lymphocytes in the spleen and bursa, and losses of lymphoid cells in thymic gland. The activities of catalase, glutathione, glutathione peroxidase, and superoxide dismutase in both the spleen and serum were affected by BDE-209. Obvious bioaccumulation effect was found in spleen tissues (high to 1339 ± 181.9 μg/kg). Furthermore, transcriptome sequencing analyses of the spleen identified 424 upregulated and 301 downregulated DEGs, and the cytokine-cytokine receptor interaction signal pathway was most significantly enriched based on the Kyoto Encyclopedia of Genes and Genomes database. Quantitative real-time PCR affirmed the decreased expressions of interleukin IL18, IL18R1, IL18RAP, IL21, as well as interferon gamma IFNG and tumor necrosis factor superfamily members TNFSF8, indicating significant interference to immunomodulation function and possible disease progression in inflammatory effects resulting from BDE-209 exposure. The immunotoxicity of BDE-209 may cause the suppression of immune and physiological functions of spleen cells, leading to inflammation and apoptosis and ultimately spleen atrophy.

Evaluation of exposure to secondhand smoke and serum level of interleukin 18 in non-smokers

Objective

Smoking is one significant global health care problems, that not only affects the users but also endangers the health of people inhaling the smoke (passive smoking/secondhand smoke). The serum level of IL-18, an important regulator of inherent and acquired immune response, is affected by cigarette smoking. The aim of this study was to evaluate the effect of secondhand smoke (SHS) exposure on IL-18 serum level in non-smoker adults.

Methods

In a case-control study, using easy sampling method, 76 non-smokers who were exposed to cigarette smoke for at least 1 h daily during the past year were considered as exposure group, while 76 of their companions without exposure to cigarette smoke (after matching age) were considered as non-exposure group. Serum IL-18 levels were measured for all participants and finally compared between the two groups using Chi-square test. P value < 0.05 was considered to be statistically significant.

Results

The exposure and non-exposure groups included 58 (76.3%) and 25 (32.9%) males, respectively (P < 0.001). The mean ± SD of age for the exposure and non-exposure groups was 35.42 ± 10.37 and 38.47 ± 12.49 years, respectively (P = 0.102). There was no significant difference between the mean serum levels of IL-18 in the exposure (54.81 ± 57.03 ng/ml) and non-exposure (41.49 ± 42.14 ng/ml) groups (P = 0.104).

Conclusion

The exposure to secondhand smoke has no significant effect on serum level of IL-18 in exposed adult individuals. However, more studies with larger sample sizes on different populations are required to confirm these results.

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Smoking is one significant global health care problems.

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That not only affects the users but also endangers the health of people inhaling the smoke.

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The serum level of IL-18, an important regulator of inherent and acquired immune response.

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The exposure to secondhand smoke has no significant effect on serum level of IL-18.

The risk of atopic dermatitis may be affected by IL-1B +3954 C/T and IL-18 -137G/C polymorphisms: evidence from a meta-analysis

Introduction

Whether Th1-related cytokine polymorphisms influence the risk of atopic dermatitis (AD) remain inconclusive.

Aim

The authors performed a meta-analysis to robustly explore relationships between Th1-related cytokine polymorphisms and the risk of AD by merging the results of eligible publications.

Material and methods

The authors strictly adhere to the PRISMA guidelines in study design and implementation. A thorough literature search in Medline, Embase, Wanfang, VIP and CNKI was performed by the authors to identify eligible publications. Relationships between TNF-α/IL-1/IL-6/IL-18 polymorphisms and the risk of AD were estimated with odds ratio and its 95% confidence interval. The statistically significant p value was set at 0.05. The quality of eligible publications was assessed by the Newcastle-Ottawa scale (NOS).

Results

In total twenty-one publications with a NOS score of 7-8 were selected for merged quantitative analyses. We have noticed that genotypic frequencies of IL-1B +3954 C/T and IL-18 -137G/C polymorphisms among cases with AD and population-based controls differed significantly. Moreover, we have found that genotypic frequency of IL-1B +3954 C/T polymorphism among cases with AD and population-based controls of Caucasian origin differed significantly, and genotypic frequency of IL-18 -137G/C polymorphism among cases with AD and population-based controls of both Caucasian and Asian origins also differed significantly. However, we did not observe such genotypic distribution differences for TNF-α -238 G/A, TNF-α -308 G/A, IL-1A -889 C/T, IL-1B −511 C/T and IL6 -174 G/C polymorphisms.

Conclusions

The present meta-analysis shows that IL-1B +3954 C/T and IL-18 -137G/C polymorphisms may affect the risk of AD.

Associations of Single Nucleotide Polymorphisms in IL-18 Gene with Plasmodium falciparum-Associated Malaria

Introduction

Interleukin-18 (IL-18) is a pro-inflammatory cytokine, reported to be involved in the initial immune responses against malaria. Genetic variations in the host are an important factor that influences the etiology of malaria at several disease levels. Polymorphisms within the IL-18 gene are associated with susceptibility and clinical outcome of several diseases.

Methods

We genotyped single nucleotide polymorphisms (SNPs) in IL-18 of patients infected with Plasmodium falciparum with varying extent of parasitemia and different age groups.

Results

SNPs rs5744292 (OR = 70.446; 95% CI = 4.318-1149.323; p<0.0001) and rs544354 (OR = 1.498; 95% CI = 1.088-2.063; p=0.013) were found to be significantly associated with parasitemia in P. falciparum-infected patients when compared with healthy control subjects. SNP rs5744292 (OR = 7.597; 95% CI=1.028-56.156; p=0.019) was associated with increased parasite density in infected patients. SNPs rs544354 (OR 0.407; 95% CI=0.204-0.812; p = 0.009) and rs360714 (OR of 0.256; 95% CI=0.119-0.554; p = 0.001) were significantly associated with parasite density in an age-dependent manner, with the risk alleles present more frequently among the younger (1-9 years) patients. Several haplotypes were found to have a significant association with parasitemia. In-vitro expression analysis using luciferase reporter assay showed that SNPs rs1946518 and rs187238 in the IL-18 gene promoter region and rs360728 and rs5744292 in the 3'-untranslated region of the IL-18 gene were associated with enhanced transcriptional activity.

Conclusion

Our results suggest that polymorphisms within the IL-18 gene are associated with the susceptibility to P. falciparum infection and related parasitemia among groups with different parasite density and across various age groups.

Uncovering Potential lncRNAs and mRNAs in the Progression From Acute Myocardial Infarction to Myocardial Fibrosis to Heart Failure

Background: Morbidity and mortality of heart failure (HF) post-myocardial infarction (MI) remain elevated. The aim of this study was to find potential long non-coding RNAs (lncRNAs) and mRNAs in the progression from acute myocardial infarction (AMI) to myocardial fibrosis (MF) to HF.

Methods: Firstly, blood samples from AMI, MF, and HF patients were used for RNA sequencing. Secondly, differentially expressed lncRNAs and mRNAs were obtained in MF vs. AMI and HF vs. MF, followed by functional analysis of shared differentially expressed mRNAs between two groups. Thirdly, interaction networks of lncRNA-nearby targeted mRNA and lncRNA-co-expressed mRNA were constructed in MF vs. AMI and HF vs. MF. Finally, expression validation and diagnostic capability analysis of selected lncRNAs and mRNAs were performed.

Results: Several lncRNA-co-expressed/nearby targeted mRNA pairs including AC005392.3/AC007278.2-IL18R1, AL356356.1/AL137145.2-PFKFB3, and MKNK1-AS1/LINC01127-IL1R2 were identified. Several signaling pathways including TNF and cytokine–cytokine receptor interaction, fructose and mannose metabolism and HIF-1, hematopoietic cell lineage and fluid shear stress, and atherosclerosis and estrogen were selected. IL1R2, IRAK3, LRG1, and PLAC4 had a potential diagnostic value for both AMI and HF.

Conclusion: Identified AC005392.3/AC007278.2-IL18R1, AL356356.1/AL137145.2-PFKFB3, and MKNK1-AS1/LINC01127-IL1R2 lncRNA-co-expressed/nearby targeted mRNA pairs may play crucial roles in the development of AMI, MF, and HF.

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)

Association of interleukin-18 gene polymorphisms with Takayasu arteritis in a Chinese Han population

Background:

Interleukin-18 (IL18) gene polymorphisms are related to many inflammatory and autoimmune diseases. However, a correlation analysis between IL18 −607C/A and −137G/C gene polymorphisms and Takayasu arteritis (TA) is lacking.

Methods:

This study enrolled 200 patients with TA as the case group and 334 region-, age-, and sex-matched healthy subjects as the control group. We genotyped alleles and genotypes at positions −607 and −137 of the IL18 gene and analyzed the distribution frequencies. Mann-Whitney U test, t test, Chi-squared test and Hardy-Weinberg equilibrium were performed.

Results:

After adjusting for risk factors, the adjusted odds ratios and 95% confidence intervals at position −607C/A were 0.533, 0.391 to 0.880 (P = 0.010); 0.266, 0.586 to 1.002 (P = 0.051); and 0.122, 0.552 to 1.420 (P = 0.613) under the dominant, additive, and recessive models, respectively. For the −137G/C polymorphism, the adjusted odds ratios and 95% confidence intervals were 1.571, 1.068 to 2.311 (P = 0.022); 1.467, 1.086 to 1.980 (P = 0.012); and 1.815, 0.901 to 3.656 (P = 0.095) under the dominant, additive, and recessive models, respectively. Moreover, regardless of the model used, we found no statistical difference in distribution frequency between the active and quiescent states of TA for the −607C/A (P = 0.355, 0.631, and 0.705, respectively) and −137G/C polymorphisms (P = 0.205, 0.385, and 0.208, respectively).

Conclusions:

The IL18 −607C/A gene polymorphism may decrease the risk of TA, and thus is a protective factor, whereas −137G/C may increase the risk of TA, and thus is a risk factor. However, neither polymorphism was related to activity (active vs. quiescent) of TA.

The Nlrp3 inflammasome as a "rising star" in studies of normal and malignant hematopoiesis

Recent investigations indicate that hematopoiesis is coregulated by innate immunity signals and by pathways characteristic of the activation of innate immunity cells that also operate in normal hematopoietic stem progenitor cells (HSPCs). This should not be surprising because of the common developmental origin of these cells from a hemato/lymphopoietic stem cell. An important integrating factor is the Nlrp3 inflammasome, which has emerged as a major sensor of changes in body microenvironments, cell activation, and cell metabolic activity. It is currently the best-studied member of the inflammasome family expressed in hematopoietic and lymphopoietic cells, including also HSPCs. It is proposed as playing a role in (i) the development and expansion of HSPCs, (ii) their release from bone marrow (BM) into peripheral blood (PB) in stress situations and during pharmacological mobilization, (iii) their homing to BM after transplantation, and (iv) their aging and the regulation of hematopoietic cell metabolism. The Nlrp3 inflammasome is also involved in certain hematological pathologies, including (i) myelodysplastic syndrome, (ii) myeloproliferative neoplasms, (iii) leukemia, and (iv) graft-versus-host disease (GvHD) after transplantation. The aim of this review is to shed more light on this intriguing intracellular protein complex that has become a “rising star” in studies focused on both normal steady-state and pathological hematopoiesis.

Toward targeting inflammasomes: insights into their regulation and activation

Inflammasomes are multi-component signaling complexes critical to the initiation of pyroptotic cell death in response to invading pathogens and cellular damage. A number of innate immune receptors have been reported to serve as inflammasome sensors. Activation of these sensors leads to the proteolytic activation of caspase-1, a proinflammatory caspase responsible for the cleavage of proinflammatory cytokines interleukin-1β and interleukin-18 and the effector of pyroptotic cell death, gasdermin D. Though crucial to the innate immune response to infection, dysregulation of inflammasome activation can lead to the development of inflammatory diseases, neurodegeneration, and cancer. Therefore, clinical interest in the modulation of inflammasome activation is swiftly growing. As such, it is imperative to develop a mechanistic understanding of the regulation of these complexes. In this review, we divide the regulation of inflammasome activation into three parts. We discuss the transcriptional regulation of inflammasome components and related proteins, the post-translational mechanisms of inflammasome activation, and advances in the understanding of the structural basis of inflammasome activation.

Elevated Serum Interleukin-18 Level is Correlated with Vascular Access Dysfunction in Patients on Maintenance Haemodialysis

Introduction: We evaluated the impact of serum interleukin-18 (IL-18) level on short-term vascular access (VA) function in chronic haemodialysis (HD) patients. Materials and Methods: Samples were collected from 80 clinically stable patients (58.8% were men) with a mean age of 60.9 years (standard deviation 11.7 years) who were undergoing maintenance HD and were followed up for 1 year. Multivariate logistic regression was used to analyse data on demographics, biochemical parameters and serum IL-18 level to predict VA dysfunction events. The cut-off for IL-18 was derived from the highest score obtained on Youden index. Survival data was analysed using Cox proportional hazards regression analysis and Kaplan-Meier method. Results: Patients were classified as having either low IL-18 (<199.3 pg/mL) or high IL-18 (≥199.3 pg/mL). Multivariate logistic regression showed that serum IL-18 level was independently correlated with VA dysfunction events; patients with high IL-18 had a higher risk of VA dysfunction events than those with low IL-18 (odds ratio 9.47, 95% confidence interval 1.75–51.31, P = 0.009). In patients with high IL-18, Kaplan- Meier survival analysis found that incidence of VA dysfunction was significantly higher than patients with low IL-18 (P = 0.047). After adjustment for age, gender, inflammation (C-reactive protein) and calcium-phosphorus metabolism, decreased serum albumin and increased serum IL-18 levels were found to be independent prognostic predictors of VA dysfunction. Conclusion: HD patients with high IL-18 level tend to have worse rates of VA dysfunction. In HD outpatients, IL-18 is an independent risk factor for short-term VA dysfunction. Key words: Access survival, Cytokines, Short-term

Associations between twelve common gene polymorphisms and susceptibility to hepatocellular carcinoma: evidence from a meta-analysis

Background

Associations between polymorphisms in vitamin D receptor (VDR)/vascular endothelial growth factor (VEGF)/interleukin-18 (IL-18)/mannose-binding lectin (MBL) and susceptibility to hepatocellular carcinoma (HCC) were already explored by many studies, yet the results of these studies were inconsistent. The aim of this meta-analysis was to better clarify associations between polymorphisms in VDR/VEGF/IL-18/MBL and HCC by combing the results of all relevant studies.

Methods

Eligible publications were searched from PubMed, Embase, WOS, and CNKI. We used Review Manager to combine the results of individual studies.

Results

Thirty studies were included in this study. Combined results revealed that VDR rs7975232, VDR rs2228570, VEGF rs699947, VEGF rs3025039, IL-18 rs1946518, and MBL rs7096206 polymorphisms were all significantly associated with HCC in the overall pooled population. We also obtained similar significant associations for VDR rs7975232, VDR rs2228570, IL-18 rs1946518, and MBL rs7096206 polymorphisms in Asians.

Conclusions

Collectively, this meta-analysis proved that VDR rs7975232, VDR rs2228570, VEGF rs699947, VEGF rs3025039, IL-18 rs1946518, and MBL rs7096206 polymorphisms may confer susceptibility to HCC in certain populations.

To See or Not to See: A Systematic Review of the Importance of Human Ocular Surface Cytokine Biosignatures in Ocular Allergy

Cytokines are key cell signalling proteins in a number of immune and homeostatic pathways of the human body. In particular, they mediate intracellular mechanisms of allergy on the ocular surface by triggering cellular responses that result in typical physiological ocular allergy symptoms, such as itchiness, watery eyes, irritation, and swelling. Given the recent research focus in optometry on the aetiology of corneal ectasia subtypes like keratoconus, there is an increasing need for the development of new clinical diagnostic methods. An increasing trend is evident among recent publications in cytokine studies, whereby the concentrations of cytokines in healthy and disease states are compared to derive a specific cytokine profile for that disease referred to as ‘biosignatures’. Biosignatures have diagnostic applications in ocular allergy as a cheap, non-invasive alternative to current techniques like IgE antibody testing and skin prick tests. Cytokine detection from tear samples collected via microcapillary flow can be analysed either by enzyme-linked immunosorbent assays (ELISA), multiplex magnetic bead assays, or immunoblot assays. Characterising patient hypersensitivities through diagnostic tests is the first step to managing exposure to triggers. Investigating cytokine biosignatures in ocular allergy and their links to physiology are imperative and will be the focus of this systematic review article.

Inflammation in human adipose tissues-Shades of gray, rather than white and brown

Chronic inflammation in adipose tissues has been associated with obesity and metabolic syndrome over the years. Various studies using animal models have contributed to our knowledge on the pro- and anti- inflammatory mediators that regulate obesity. Analyses of cytokine profiles in humans have not revealed a clear scenario. Likewise, treatments targeting inflammation to control obesity and insulin resistance has not yielded promising results. In this review we summarize the data available in human obesity and discuss the possible reasons that could explain the difficulties in treating obesity and insulin resistance by targeting pro-inflammatory cytokines.

IL18 rs360719 A>G, IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G polymorphisms and risk of gastric cardiac adenocarcinoma

The present study was conducted to investigate the association between gastric cardiac adenocarcinoma (GCA) and four functional single-nucleotide polymorphisms (SNPs), including interleukin 18 (IL18) rs360719 A>G, IL18 receptor 1 (IL18R1) rs13015714 G>T, IL18 receptor accessory protein (IL18RAP) rs917997 C>T and interleukin 28B (IL28B) rs8099917 T>G variants. A hospital-based case-control study was performed to evaluate the genetic effects of these SNPs. A total of 243 GCA cases and 476 controls were enrolled in this study. A custom-by-design 48-Plex SNPscan™ kit was used to determine the genotypes. When the IL18 rs360719 AA homozygote genotype was used as the reference group, the AG genotype was not associated with the risk for GCA; the GG genotype was also not associated with the risk for GCA. In the dominant model, the IL18 rs360719 AG/GG variants were not associated with the risk for GCA, compared with the IL18 rs360719 AA genotype. In the recessive model, when the IL18R1 rs13015714 AA/AG genotypes were used as the reference group, the GG homozygote genotype was not associated with risk for GCA. No association was observed between IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G polymorphisms and the risk for GCA. These results demonstrated that the functional polymorphisms IL18 rs360719 A>G, IL18R1 rs13015714 G>T, IL18RAP rs917997 C>T and IL28B rs8099917 T>G do not contribute to GCA susceptibility. However, as the statistical power of our study was limited, large well-designed studies and further functional investigations are required to confirm our findings.

Inflammasomes and intestinal inflammation

The inflammasome is a cytosolic multi-protein innate immune rheostat, sensing a variety of endogenous and environmental stimuli, and regulating homeostasis or damage control. In the gastrointestinal tract, inflammasomes orchestrate immune tolerance to microbial and potentially food-related signals or drive the initiation of inflammatory responses to invading pathogens. When inadequately regulated, intestinal inflammasome activation leads to a perpetuated inflammatory response leading to immune pathology and tissue damage. In this review, we present the main features of the predominant types of inflammasomes participating in intestinal homeostasis and inflammation. We then discuss current controversies and open questions related to their functions and implications in disease, highlighting how pathological inflammasome over-activation or impaired function impact gut homeostasis, the microbiome ecosystem, and the propensity to develop gut-associated diseases. Collectively, understanding of the molecular basis of intestinal inflammasome signaling may be translated into clinical manipulation of this fundamental pathway as a potential immune modulatory therapeutic intervention.

Kidney Transplantation, Polymorphisms of IL-18, and Other Pro-Inflammatory Genes and Late Post-Transplant Outcome

BACKGROUND

Functional polymorphisms of molecules involved in immune-mediated mechanisms of allograft rejection could be predictive of increased risk for early and late post-transplant complications. In the past years, the challenge for long-term graft survival in kidney recipients is the implementation of personalized approaches. In this study, effects of interleukin (IL)-18-137G/C (rs187238), -607C/A (rs1946518), and other pro-inflammatory cytokine gene polymorphisms (tumor necrosis factor [TNF]-α-308G/A, rs1800629, IL-6-174G/C, rs1800795, and interferon [IFN]-γ+874A/T, rs2430561) on the main post-transplant risk parameters and diseases (metabolic, cardiovascular, infective, and chronic allograft rejection) were assessed in kidney-transplanted patients.

METHODS

One hundred seventy-nine transplanted patients were retrospectively analyzed for clinical and biochemical parameters and onset of post-transplant complications. Taqman allelic discrimination and PCR-SSP (polymerase chain reaction-sequence specific primers) techniques were used for genotyping.

RESULTS

No predictive effects of allele and genotypes of IL-18-607C/A, TNF-α-308G/A, IL-6-174G/C, and IFN-γ+874A/T gene polymorphisms and onset of risk factors and late complications were evidenced. However, Kaplan-Meier analysis evidenced a weak effect of IL-18-137G/C genotypes on graft survival.

CONCLUSIONS

Analyzing associations between some pro-inflammatory cytokine gene polymorphisms and onset of the most relevant risk factors and late complications of kidney transplant, results suggested a possible impact of IL-18-137G/C genotypes on graft survival, which deserves further studies.

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.

IL18 Gene Variants Influence the Susceptibility to Chagas Disease

Chagas disease is a parasitic disorder caused by the infection with the flagellated protozoan Trypanosoma cruzi. According to the World Health Organization, more than six million people are currently infected in endemic regions. Genetic factors have been proposed to influence predisposition to infection and development of severe clinical phenotypes like chronic Chagas cardiomyopathy (CCC). Interleukin 18 (IL18) encodes a proinflammatory cytokine that has been proposed to be involved in controlling T. cruzi infection. In this study, we analyzed the possible role of six IL18 gene variants (rs5744258, rs360722, rs2043055, rs187238, rs1946518 and rs360719), which cover most of the variation within the locus, in the susceptibility to infection by T. cruzi and/or CCC. In total, 1,171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n = 595), seropositive asymptomatic (n = 175) and CCC (n = 401), were genotyped using TaqMan probes. Significant associations with T. cruzi infection were observed when comparing seronegative and seropositive individuals for rs187238 (P = 2.18E-03, OR = 0.77), rs360719 (P = 1.49E-03, OR = 0.76), rs2043055 (P = 2.52E-03, OR = 1.29), and rs1946518 (P = 0.0162, OR = 1.22). However, dependence analyses suggested that the association was mainly driven by the polymorphism rs360719. This variant is located within the promoter region of the IL18 gene, and it has been described that it creates a binding site for the transcription factor OCT-1 affecting IL-18 expression levels. In addition, no evidence of association was observed between any of the analyzed IL18 gene polymorphisms and the development of CCC. In summary, our data suggest that genetic variation within the promoter region of IL18 is directly involved in the susceptibility to infection by T. cruzi, which provides novel insight into disease pathophysiology and adds new perspectives to achieve a more effective disease control.

Association between Interleukin-18 Polymorphisms and Hepatocellular Carcinoma Occurrence and Clinical Progression

We investigated the association between interleukin-18 (IL-18) polymorphisms and the susceptibility and clinicopathological state of hepatocellular carcinoma (HCC). In total, 901 participants, including 559 healthy controls and 342 patients with HCC, were recruited. The allelic discrimination of -607A/C (rs1946518) and -137G/C (rs187238) polymorphisms of IL-18 was assessed through real-time polymerase chain reaction by performing the TaqMan assay. The IL-18 -137G/C polymorphism but not the -607A/C polymorphism showed a significant association with the risk of HCC. Participants carrying the IL-18 -137 polymorphism with heterozygous G/C and homozygous CC genotypes showed a 1.987-fold increase (95% CI = 1.301-3.032; p = 0.001) in the risk of HCC compared with those homozygous for wild-type G/G. The 342 patients with HCC carrying the IL-18 -137G/C polymorphism were positive for hepatitis B virus (HBV) infection with an adjusted odds ratio of 1.668. Moreover, the 142 HBV positive patients with HCC and the IL-18 -137 polymorphism were positive for at least one C genotype and showed significant vascular invasion (p = 0.018). Furthermore, the level of α-fetoprotein was high in the patients carrying the IL-18 -137 polymorphism with GC+CC alleles (p = 0.011). In conclusion, the IL-18 -137G/C polymorphism with a GC+CC genotype could be a factor that increases the risk of HCC. Furthermore, the correlation between the IL-18 -137G/C polymorphism and HCC-related HBV infection is a risk factor for vascular invasion and has a synergistic effect that can further enhance HCC prognosis.

Association of the interleukin-18 receptor 1 and interleukin-18 receptor accessory protein polymorphisms with the risk of esophageal cancer

Esophageal cancer is the fourth leading cause of cancer-associated fatalities and the fourth most commonly diagnosed cancer. In addition to environmental risk factors, genetic factors may have a significant role in esophageal cancer carcinogenesis. A hospital-based case-control study was conducted to evaluate the genetic effects of functional single-nucleotide polymorphisms in the interleukin-18 (IL-18), IL-18 receptor 1 protein (IL-18R1), IL-18 receptor accessory protein (IL-18RAP) and IL-28B on the development of esophageal cancer. In total, 380 esophageal squamous cell carcinoma (ESCC) cases and 380 controls were recruited for the present study. The IL-18 rs360719 A>G, IL-18R1 rs13015714 G>T, IL-18RAP rs917997 C>T and IL-28B rs8099917 T>G genotypes were determined. No association was observed between the IL-18R1 rs13015714 G>T, IL-18RAP rs917997 C>T and IL-28B rs8099917 T>G polymorphisms and the risk of ESCC. However, in stratification analyses, a significantly decreased risk of ESCC associated with the IL-18R1 rs13015714 G>T polymorphism and a significantly increased risk of ESCC associated with the IL-18RAP rs917997 C>T polymorphism was evident among male patients and patients who smoked or consumed alcohol. These findings highlighted that functional polymorphisms IL-18R1 rs13015714 G>T and IL-18RAP rs917997 C>T may contribute to ESCC susceptibility among these subgroups. However, the present results were obtained with a limited sample size and further epidemiological studies are warranted to clarify the role of IL-18R1 and IL-18RAP variants in the development of ESCC.

[Plasma IL-18 levels are related to insulin and are modulated by IL-18 gene polymorphisms]

INTRODUCTION

Atherosclerosis is an inflammatory chronic disease influenced by multiple factors. Different prospective studies have shown that plasmatic levels of inflammatory markers were related to atherosclerosis and cardiovascular disease.

OBJECTIVE

To evaluate whether plasmatic levels of interleukin 18 (IL-18) are modulated by SNPs (single nucleotide polymorphisms) of the IL 18 gene and its possible association with insulin levels and other cardiovascular risk factors.

METHODS

746 individuals were studied for a period of two years by opportunistic selection in the metropolitan area of Valencia. Parameters of lipid and glucose metabolism were analyzed by standard methodology. IL-18 was measured by ELISA.

RESULTS

Individuals with insulin resistance showed significant higher levels of IL-18. IL 18 was significantly correlated with insulin levels and other cardiovascular risk factors. The CC genotype of the rs1834481 SNP was significantly associated with lower levels of IL-18. However, the GG genotype of the rs7559479 was associated with significant higher levels of IL-18.

CONCLUSION

IL-18 is associated with insulin resistance and other cardiovascular risk factors, being those levels genetically regulated.

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.

Association between interleukin-18 gene polymorphism and Helicobacter pylori infection in the Korean population

Interleukin-18 (IL-18) is a pleiotropic, pro-inflammatory cytokine that is capable of promoting the Th1 response. A predominant Th1 response induces chronic and persistent inflammatory changes in the gastric mucosa in response to Helicobacter pylori (H. pylori) infection. The aim of this study was to investigate the potential association between IL-18 gene polymorphisms and susceptibility to H. pylori infection in the Korean population. A total of 678 subjects who underwent a routine health check-up were enrolled. The IL-18 gene polymorphisms at positions −656, −607, −137, +113, and +127 were genotyped. H. pylori positivity was demonstrated in 456 subjects (67.3%). The allele frequencies of IL-18 gene polymorphisms at position −137 (rs187238) were different based on the status of H. pylori infection (G vs. C, adjusted OR 0.64 CI: 0.47–0.87, P = 0.005). The results indicate that the genetic variants in the IL-18 gene may be associated with susceptibility to H. pylori infection in the Korean population, suggesting that IL-18 plays a role in the pathogenesis of H. pylori-associated diseases. However, this finding requires further replication and validation.

Role of inflammasomes in intestinal inflammation and Crohn's disease

: Inflammasomes are multiprotein complexes that process procytokines into mature forms of interleukin 1β and interleukin 18 and induce pyroptotic cell death. Evidence linking NLRP3, NLRC4, and NLRP6 inflammasomes to intestinal inflammation is reviewed to provide a basis to understand how the innate immune system discriminates pathogenic bacteria from commensal bacteria and shapes microbial ecology. Inflammasomes have a direct and important role limiting colitis by directing effective immune responses against pathogenic bacterial infections in the intestine. Chronic granulomatous disease is presented to reveal a contrasting proinflammatory effect of inflammasomes. This pathogenic effect is unmasked in a state of immunodeficiency where bacterial growth is poorly controlled increasing inflammasome activity. The role of inflammasomes in inflammation associated with Crohn's disease and ulcerative colitis is discussed. Finally, mechanistic studies linking genetic polymorphisms in ATG16L and NOD2 to inflammasome activation provide a basis for new hypotheses to explain how genetic polymorphism associated with Crohn's disease modulate intestinal inflammation. A deeper understanding of the role of inflammasomes in intestinal inflammation is expected to identify new ways of treating inflammatory bowel disease.

Genetic polymorphisms of Interleukin-18 are not associated with allograft function in kidney transplant recipients

Interleukin 18 (IL-18) is a proinflammatory cytokine that plays a role in host defense by upregulating both innate and acquired immune responses. Analysis of IL18 polymorphisms may be clinically important since their roles have been recognized in a variety of inflammatory and autoimmune disorders. However, the role of this cytokine polymorphisms in kidney transplant still remains unclear. In this study, we evaluated the associations between IL18 polymorphisms and graft function assessed by creatinine clearance in kidney transplant recipients. A total of 82 kidney transplant recipients and 183 healthy controls were enrolled, and frequencies of alleles, genotypes and haplotypes for IL18 polymorphisms were determined and compared with creatinine clearance. The -607C/A (rs1946518) and -137C/G (rs187238) variant alleles in the IL18 gene were determined by polymerase chain reaction. In our study, no significant association was found between the IL18 variants and creatinine clearance (p > 0.05). Nonetheless, polymorphism analysis revealed an increase in the frequency of the IL18 major haplotype -607C/-137G in kidney transplant patients (odds ratio 2.57, 95% confidence interval 1.45–4.55, p = 0.0014). Finally, we found that IL18 polymorphisms did not influence the renal function and that IL18 haplotype -607C/-137G seems to be associated with kidney transplant recipients.

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.

Association between interleukin 18 polymorphisms and alopecia areata in Koreans

Interleukin 18 (interferon gamma-inducing factor) (IL18) is an important proinflammatory cytokine that belongs to the IL1 family. This study investigated whether IL18 single-nucleotide polymorphisms (SNPs) are associated with the susceptibility to alopecia areata (AA) in a Korean population. Two hundred thirty-three AA patients and 243 healthy control subjects were recruited. One promoter SNP (rs187238, -137G/C) and exonic SNP (rs549908, Ser35Ser) in IL18 were genotyped using direct sequencing. SNPStats, SPSS 18.0, and Haploview version 4.2 programs were used to evaluate genetic data. Multiple logistic regression models were used to determine odds ratios, 95% confidence intervals, and P values. Tested 2 SNPs (rs187238 and rs549908) were associated with the development of AA (rs187238, P=0.002 in a codominant model 1, P=0.0048 in a dominant model, P=0.02 in a log-additive model, P=0.023 in allele distribution; rs549908, P=0.003 in a codominant model 1, P=0.0052 in a dominant model, P=0.016 in a log-additive model, P=0.015 in allele distribution). Our data suggest that the IL18 may be a risk factor for AA susceptibility.

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.

Genetic polymorphisms and associated susceptibility to asthma

As complex common diseases, asthma and allergic diseases are caused by the interaction of multiple genetic variants with a variety of environmental factors. Candidate-gene studies have examined the involvement of a very large list of genes in asthma and allergy, demonstrating a role for more than 100 loci. These studies have elucidated several themes in the biology and pathogenesis of these diseases. A small number of genes have been associated with asthma or allergy through traditional linkage analyses. The publication of the first asthma-focused genome-wide association (GWA) study in 2007 has been followed by nearly 30 reports of GWA studies targeting asthma, allergy, or associated phenotypes and quantitative traits. GWA studies have confirmed several candidate genes and have identified new, unsuspected, and occasionally uncharacterized genes as asthma susceptibility loci. Issues of results replication persist, complicating interpretation and making conclusions difficult to draw, and much of the heritability of these diseases remains undiscovered. In the coming years studies of complex diseases like asthma and allergy will probably involve the use of high-throughput next-generation sequencing, which will bring a tremendous influx of new information as well as new problems in dealing with vast datasets.

Impact of interleukin-13 and -18 promoter polymorphisms in health care workers with natural rubber latex allergy

It is a matter of debate whether single nucleotide polymorphisms (SNP) in the promoter region of interleukin (IL)-13, an IgE regulator, and IL-18, an inducer of immune responses, modulating the respective protein expression, are accompanied by an increased risk of atopy, allergic asthma, and total IgE levels. The suspected associations were noted in health care workers (HCW) with and without latex allergy. IL-13 (-1055C>T) and three IL-18 (-656T>G, -607C>A, -137G>C) SNP were studied in 523 HCW with natural rubber latex (NRL) exposure and diagnosis in the late 1990s. Three hundred and thirty-four HCW displayed NRL sensitization and allergic symptoms, 93 with latex-allergic asthma, and 189 HCW with neither symptoms nor NRL sensitization. SNP analyses were performed by real-time polymerase chain reaction (PCR) using newly developed LightCycler assays. Analysis of IL-13 -1055C>T by analysis of variance (ANOVA) revealed significantly elevated total IgE levels in HCW carrying the CT or TT variant compared with the CC variant. None of the studied SNP showed an association with NRL-specific IgE. The IL-18 variants -656GG and -607CC displayed 99.5% linkage disequilibrium. Frequencies of alleles -656GG and -607CC were elevated in HCW with NRL asthma (48.4%) compared with HCW without symptoms (37.6%). In contrast, IL-18 -137G>C variants displayed an overall homogenous distribution. The association between the IL-13 -1055T allele and elevated total IgE levels confirms the role of a genetic background for total IgE regulation. The studied IL-18 SNP demonstrated no significant association with the clinical outcome, total IgE, or specific IgE in HCW with natural rubber latex allergy.

Circulating levels of IL-18 are significantly influenced by the IL-18 +183 A/G polymorphism in coronary artery disease patients with diabetes type 2 and the metabolic syndrome: an observational study

BACKGROUND

Increased IL-18 serum levels have been associated with diabetes type 2, metabolic syndrome and the severity of atherosclerosis. The present study investigated the presence and influence of IL-18 genetic variants on gene- and protein expression in stable coronary artery disease (CAD) patients.

METHODS

The +183 A/G (rs 5744292), -137 G/C (rs 187238) and -607 C/A (rs 1946518) polymorphisms were determined in 1001 patients with angiographically verified stable CAD, and in 204 healthy controls. IL-18 gene-expression was measured in circulating leukocytes in 240 randomly selected patients. Circulating IL-18 and IL-18 binding protein levels were measured immunologically in all patients.

RESULTS

The +183 G-allele associated significantly with lower serum levels of IL-18 (p = 0.002, adjusted for age, glucose, body mass index and gender) and a 1.13- fold higher IL-18 gene-expression (p = 0.010). No influence was observed for the -137 G/C and -607 C/A polymorphisms. The IL-18 binding protein levels were not influenced by IL-18 genotypes. IL-18 levels were significantly higher in men as compared to women, and in patients with diabetes type 2 and metabolic syndrome compared to those without (p ≤ 0.001, all). The reduction in IL-18 levels according to the +183 G-allele was 3-4 fold more pronounced in diabetes and metabolic syndrome as compared to unaffected patients.Finally, the +183 AA genotype was more frequent in patients with hypertension (p = 0.042, adjusted for age, body mass index and gender).

CONCLUSION

The reduction in serum IL-18 levels across increasing numbers of +183 G-alleles was especially apparent in patient with diabetes type 2 and metabolic syndrome, suggesting a beneficial GG genotype in relation to cardiovascular outcome in these patients.

CLINICAL TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT00222261.

Functional promoter haplotypes of interleukin-18 condition susceptibility to severe malarial anemia and childhood mortality

Severe malarial anemia (SMA) is a leading cause of morbidity and mortality in children residing in regions where Plasmodium falciparum transmission is holoendemic. Although largely unexplored in children with SMA, interleukin-18 (IL-18) is important for regulating innate and acquired immunity in inflammatory and infectious diseases. As such, we selected two functional single-nucleotide polymorphisms (SNPs) in the IL-18 promoter (-137G→C [rs187238] and -607C→A [rs1946518]) whose haplotypes encompass significant genetic variation due to the presence of strong linkage disequilibrium among these variants. The relationship between the genotypes/haplotypes, SMA (hemoglobin [Hb], <5.0 g/dl], and longitudinal clinical outcomes were then investigated in Kenyan children (n = 719). Multivariate logistic regression analyses controlling for age, gender, sickle cell trait, glucose-6-phosphate dehydrogenase (G6PD) deficiency, HIV-1, and bacteremia revealed that carriage of the -607AA genotype was associated with protection against SMA (odds ratio [OR] = 0.440 [95% confidence interval {CI} = 0.21 to 0.90], P = 0.031) in children with acute infection. In contrast, carriers of the -137G/-607C (GC) haplotype had increased susceptibility to SMA (OR = 2.050 [95% CI = 1.04 to 4.05], P = 0.039). Measurement of IL-18 gene expression in peripheral blood leukocytes demonstrated that elevated IL-18 transcripts were associated with reduced hemoglobin concentrations (ρ = -0.293, P = 0.010) and that carriers of the "susceptible" GC haplotype had elevated IL-18 transcripts (P = 0.026). Longitudinal investigation of clinical outcomes over a 3-year follow-up period revealed that carriers of the rare CC haplotype (∼1% frequency) had 5.76 times higher mortality than noncarriers (P = 0.001). Results presented here demonstrate that IL-18 promoter haplotypes that condition elevated IL-18 gene products during acute infection are associated with increased risk of SMA. Furthermore, carriage of the rare CC haplotype significantly increases the risk of childhood mortality.

Relationship between serum levels of interleukin-18, IgE and disease severity in patients with atopic dermatitis

BACKGROUND

Interleukin (IL)-18 is a pleiotropic cytokine. Synergistically with IL-12, IL-18 promotes immune responses of the T helper type, by enhancing synthesis of interferon-γ and inhibiting IgE production. IL-18 can also enhance production of IL-4 and IL-13 production, and stimulate synthesis of IgE. Moreover, in the presence of IL-3, IL-18 can directly stimulate basophils and mast cells to produce their mediators in an IgE-independent manner. These results indicate a role for IL-18 in the pathogenesis of atopic dermatitis (AD).

AIM

To examine the association of serum IL-18 with IgE levels and disease severity in patients with AD.

METHODS

ELISA was used to measure IL-18 and total IgE levels in the sera of 67 patients with AD and 50 healthy volunteers. The SCORing Atopic Dermatitis (SCORAD) tool was used to determine the severity of this disease.

RESULTS

The mean serum level of IL-18 in study group (155.68 pg/mL) was significantly higher than that of controls. IL-18 was also significantly higher in the sera of the patients with severe AD than in those with milder disease. There was a correlation with IgE and IL-18 levels, as patients who had high IgE levels also had high IL-18 levels, compared with controls.

CONCLUSION

IL-18 seems to play an important role in the pathogenesis of AD, but this requires further study. IL-18 could be a useful clinical marker of disease severity in AD.