Prognostic and immunological roles of IL18RAP in human cancers.

Across several cancers, IL18 receptor accessory protein (IL18RAP) is abnormally expressed, and this abnormality is related to tumor immunity and heterogeneous clinical outcomes. In this study, based on bioinformatics analysis, we discovered that IL18RAP is related to the human tumor microenvironment and promotes various immune cells infiltration. Additionally, the multiple immunofluorescence staining revealed that with the increased expression of IL18RAP, the number of infiltrated M1 macrophages increased. This finding was confirmed by coculture migration analysis using three human cancer cell lines (MDA-MB-231, U251, and HepG2) with IL18RAP knockdown. We discovered a positive link between IL18RAP and the majority of immunostimulators, immunoinhibitors, major histocompatibility complex (MHC) molecules, chemokines, and chemokine receptor genes using Spearman correlation analysis. Additionally, functional IL18RAP's gene set enrichment analysis (GSEA) revealed that it is related to a variety of immunological processes, such as positive regulation of interferon gamma production and positive regulation of NK cell-mediated immunity. Moreover, we used single-cell RNA sequencing analysis to detect that IL18RAP was mainly expressed in immune cells, and HALLMARK analysis confirmed that the INF-γ gene set expression was upregulated in CD8Tex cells. In addition, in human and mouse cancer cohorts, we found that the level of IL18RAP can predict the immunotherapy response. In short, our study showed that IL18RAP is a new tumor biomarker and may become a potential immunotherapeutic target in cancer.

Whole-genome sequencing reveals that variants in the Interleukin 18 Receptor Accessory Protein 3'UTR protect against ALS.

The noncoding genome is substantially larger than the protein-coding genome but has been largely unexplored by genetic association studies. Here, we performed region-based rare variant association analysis of >25,000 variants in untranslated regions of 6,139 amyotrophic lateral sclerosis (ALS) whole genomes and the whole genomes of 70,403 non-ALS controls. We identified interleukin-18 receptor accessory protein (IL18RAP) 3' untranslated region (3'UTR) variants as significantly enriched in non-ALS genomes and associated with a fivefold reduced risk of developing ALS, and this was replicated in an independent cohort. These variants in the IL18RAP 3'UTR reduce mRNA stability and the binding of double-stranded RNA (dsRNA)-binding proteins. Finally, the variants of the IL18RAP 3'UTR confer a survival advantage for motor neurons because they dampen neurotoxicity of human induced pluripotent stem cell (iPSC)-derived microglia bearing an ALS-associated expansion in C9orf72, and this depends on NF-κB signaling. This study reveals genetic variants that protect against ALS by reducing neuroinflammation and emphasizes the importance of noncoding genetic association studies.

IL18-family Genes Polymorphism Is Associated with the Risk of Myocardial Infarction and IL18 Concentration in Patients with Coronary Artery Disease.

BACKGROUND: Atherogenesis is mainly determined by endothelial dysfunction, lipid metabolism disorders and inflammation. The atherogenesis-related inflammatory process is a complex interaction between serum blood lipoproteins, inflammatory cells, endothelial and smooth muscle cells and extracellular matrix; the role of chronic inflammation in atherogenesis was proposed. MATERIAL AND METHODS: A pathogenetic role of polymorphism in NF-kB pathway genes in coronary artery disease and associated pathological conditions has been suggested in a case-control retrospective study. 260 coronary artery disease patients permanently living in a large industrial region of Russian Federation (Kemerovo region) were recruited in the study. We examined nine single nucleotide polymorphisms in IL18, IL18R1 and IL18RAP genes by polymerize chain reaction; and serum blood level of IL18 by enzyme-linked immunosorbent assay. RESULTS: Polymorphic variants rs13015714 (IL18R1) and rs917997 (IL18RAP) are associated with the risk of myocardial infarction and high serum levels of IL18. Minor alleles of rs13015714 and rs917997 sites are associated with high risk of developing multifocal atherosclerosis and arterial hypertension in patients with stable coronary artery disease after myocardial infarction. CONCLUSIONS: Thus, polymorphism in the genes of IL18 receptor is determine the IL18 contents and important in the development of coronary atherosclerosis, associated pathological conditions and the risk of acute coronary events; prospective monitoring of patients with early clinical signs of adverse events is required to confirm the role of IL18, IL18R1, and IL18RAP genes polymorphism in atherogenesis.

Deep resequencing identifies candidate functional genes in leprosy GWAS loci.

Leprosy is the second most prevalent mycobacterial disease globally. Despite the existence of an effective therapy, leprosy incidence has consistently remained above 200,000 cases per year since 2010. Numerous host genetic factors have been identified for leprosy that contribute to the persistently high case numbers. In the past decade, genetic epidemiology approaches, including genome-wide association studies (GWAS), identified more than 30 loci contributing to leprosy susceptibility. However, GWAS loci commonly encompass multiple genes, which poses a challenge to define causal candidates for each locus. To address this problem, we hypothesized that genes contributing to leprosy susceptibility differ in their frequencies of rare protein-altering variants between cases and controls. Using deep resequencing we assessed protein-coding variants for 34 genes located in GWAS or linkage loci in 555 Vietnamese leprosy cases and 500 healthy controls. We observed 234 nonsynonymous mutations in the targeted genes. A significant depletion of protein-altering variants was detected for the IL18R1 and BCL10 genes in leprosy cases. The IL18R1 gene is clustered with IL18RAP and IL1RL1 in the leprosy GWAS locus on chromosome 2q12.1. Moreover, in a recent GWAS we identified an HLA-independent signal of association with leprosy on chromosome 6p21. Here, we report amino acid changes in the CDSN and PSORS1C2 genes depleted in leprosy cases, indicating them as candidate genes in the chromosome 6p21 locus. Our results show that deep resequencing can identify leprosy candidate susceptibility genes that had been missed by classic linkage and association approaches.

Elevated Interleukin-18 Receptor Accessory Protein Mediates Enhancement in Reactive Oxygen Species Production in Neutrophils of Systemic Lupus Erythematosus Patients.

Interleukin-18 receptor accessory protein (IL18RAP) is an indispensable subunit for the IL-18 receptor (IL-18R) complex's ability to mediate high-affinity IL-18 binding and signalling transduction. Interest in IL-18 in systemic lupus erythematosus (SLE) has been mostly focused on its role as a type 1 T helper cell-driving cytokine. The functional significance of IL18RAP in mediating the IL-18-driven response in myeloid cells in SLE remains largely unexplored. This study aimed to investigate the expression and function significance of IL18RAP in neutrophils of SLE patients. By qRT-PCR and Western blot analyses, elevated expressions of IL18RAP mRNA and protein were observed in neutrophils from SLE patients-particularly those with a history of nephritis. IL18RAP expression correlated negatively with complement 3 level and positively with disease activity, with higher expression in patients exhibiting renal and immunological manifestations. The increased IL18RAP expression in SLE neutrophils could be attributed to elevated type I interferon level in sera. Functionally, neutrophils from SLE patients showed higher IL-18-mediated enhancement in reactive oxygen species (ROS) generation, which showed positive correlation with IL18RAP expression and could be neutralized by anti-IL18RAP blocking antibodies. Taken together, our findings suggest that IL-18 could contribute to SLE pathogenesis through mediation of neutrophil dysfunction via the upregulation of IL18RAP expression.

Integrating disease and drug-related phenotypes for improved identification of pharmacogenomic variants.

Aim: To improve the identification and interpretation of pharmacogenetic variants through the integration of disease and drug-related traits. Materials & methods: We hypothesized that integrating genome-wide disease and pharmacogenomic data may drive new insights into drug toxicity and response by identifying shared genetic architecture. Pleiotropic variants were identified using a methodological framework incorporating colocalization analysis. Results: Using genome-wide association studies summary statistics from the UK Biobank, European Bioinformatics Institute genome-wide association studies catalog and the Pharmacogenomics Research Network, we validated pleiotropy at the ABCG2 locus between allopurinol response and gout and identified novel pleiotropy between antihypertensive-induced new-onset diabetes, Crohn's disease and inflammatory bowel disease at the IL18RAP/SLC9A4 locus. Conclusion: New mechanistic insights and genetic loci can be uncovered by identifying pleiotropy between disease and drug-related traits.

Lay abstract Disease-focused genome-wide association studies (GWAS) have identified a plethora of actionable genetic variants over the last 20 years. International collaboration and technological breakthroughs have enabled rapid genotyping and data collection, which has correspondingly increased sample size and power. Contrastingly, recruitment of well-characterized cohorts of patients for pharmacogenomics research has proven challenging. Given the greater number of associated genetic variants and larger cohort sizes in common disease GWAS, we hypothesized that integrating genome-wide disease and pharmacogenomic data may drive new insights into drug toxicity and drug efficacy phenotypes, beyond the standard scope of current pharmacogenetic analyses. Using GWAS summary statistics from the UK Biobank, European Bioinformatics Institute GWAS catalog, and the Pharmacogenomics Research Network, and a methodological framework incorporating colocalization analysis, we validated pleiotropy at the ABCG2 locus between allopurinol response, gout, and serum urate and identified novel pleiotropy between antihypertensive-induced new-onset diabetes, Crohn's disease and inflammatory bowel disease at the IL18RAP/SLC9A4 locus.

Investigation of genetically regulated gene expression and response to treatment in rheumatoid arthritis highlights an association between IL18RAP expression and treatment response.

OBJECTIVES: In this study, we sought to investigate whether there was any association between genetically regulated gene expression (as predicted using various reference panels) and anti-tumour necrosis factor (anti-TNF) treatment response (change in erythrocyte sedimentation rate (ESR)) using 3158 European ancestry patients with rheumatoid arthritis. METHODS: The genetically regulated portion of gene expression was estimated in the full cohort of 3158 subjects (as well as within a subcohort consisting of 1575 UK patients) using the PrediXcan software package with three different reference panels. Estimated expression was tested for association with anti-TNF treatment response. As a replication/validation experiment, we also investigated the correlation between change in ESR with measured gene expression at the Interleukin 18 Receptor Accessory Protein (IL18RAP) gene in whole blood and synovial tissue, using an independent replication data set of patients receiving conventional synthetic disease modifying anti-rheumatic drugs, with directly measured (via RNA sequencing) gene expression. RESULTS: We found that predicted expression of IL18RAP showed a consistent signal of association with treatment response across the reference panels. In our independent replication data set, IL18RAP expression in whole blood showed correlation with the change in ESR between baseline and follow-up (r=-0.35, p=0.0091). Change in ESR was also correlated with the expression of IL18RAP in synovial tissue (r=-0.28, p=0.02). CONCLUSION: Our results suggest that IL18RAP expression is worthy of further investigation as a potential predictor of treatment response in rheumatoid arthritis that is not specific to a particular drug type.

Bioinformatics Analysis of Prognostic Tumor Microenvironment-Related Genes in the Tumor Microenvironment of Hepatocellular Carcinoma.

BACKGROUND Growing evidence shows that the tumor microenvironment plays a crucial role in the pathogenesis of hepatocellular carcinoma (HCC). The present work aimed to screen tumor microenvironment-related genes strongly related to prognosis and to construct a prognostic gene expression model for HCC. MATERIAL AND METHODS We downloaded gene expression data of 371 HCC patients in The Cancer Genome Atlas (TCGA). A novel ESTIMATE algorithm was applied to calculate immune scores and stromal scores for each patient. Then, the differentially-expressed genes (DEGs) were detected according to the immune and stromal scores, and tumor microenvironment-related genes were further explored. Univariate, Lasso, and multivariate Cox analyses were performed to build the tumor microenvironment-related prediction model. RESULTS Stromal and immune scores were calculated and were found to be correlated with the 3-year prognosis of HCC patients. DEGs were detected according to the stromal and immune scores. There were 49 genes with prognostic value in both TCGA and ICGC (International Cancer Genome Consortium) considered as prognostic tumor microenvironment-related genes. Univariate, Lasso, and multivariate Cox analyses were conducted. A novel 2-gene signature (IL18RAP and GPR182) was built for HCC 3-year prognosis prediction. The 2-gene signature was regarded as an independent prognostic predictor that was correlated with 3-year survival rate, as shown by Cox regression analysis. CONCLUSIONS This study offers a novel 2-gene signature to predict overall survival of patients with HCC, which has the potential to be used as an independent prognostic predictor. Overall, this study reveals more details about the tumor microenvironment in HCC and offers novel candidate biomarkers.

Increased interleukin 18 activity in adolescents with early-onset psychosis is associated with cortisol and depressive symptoms.

OBJECTIVE: Evidence indicates that the pathophysiology of adult psychosis involves immune dysregulation, but its associations with stress are often not considered. The inflammatory cytokine interleukin (IL)-18, which is elevated in adult schizophrenia, is suggested to be sensitive to stress. We compared the associations of IL-18 with cortisol and clinical variables in adolescents with early-onset psychosis (EOP) aged 12-18 years and age-matched healthy controls (HC). METHOD: We measured serum IL-18, IL-18 binding protein (IL-18BP), IL-18 receptor accessory protein (IL-18RAP), IL-18 receptor 1 (IL-18R1) and cortisol, and calculated the IL-18/IL-18BP ratio in patients (n = 31) and HC (n = 60). Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale and depressive symptoms by the Mood and Feelings Questionnaire-Child version (MFQ-C). Bivariate correlation analysis was used to explore relationships between IL-18/IL-18BP ratio and cortisol, depression and other clinical characteristics. Hierarchical multiple linear regression analysis was used to assess their individual contributions to the variance of the IL-18/IL-18BP ratio. RESULTS: Patients had significantly higher IL-18 levels and IL-18/IL-18BP ratios than HC, but similar IL-18BP, IL-18RAP and IL-18R1. Both cortisol (R2 change = 0.05) and the MFQ-C score (R2 change = 0.09) contributed significantly to the variance in IL-18/IL-18BP ratios after controlling for confounders. CONCLUSION: We found increased IL-18 system activity in adolescents with EOP. Cortisol and depressive symptoms each contributed to the variance in the IL-18/IL-18BP ratio. Our findings support activation of inflammatory pathways in adolescent psychosis and suggest interactions between stress, inflammation and depressive symptoms in EOP.

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study in multiple populations.

BACKGROUND: Extranodal natural killer T-cell lymphoma (NKTCL; nasal type) is an aggressive malignancy with a particularly high prevalence in Asian and Latin American populations. Epstein-Barr virus infection has a role in the pathogenesis of NKTCL, and HLA-DPB1 variants are risk factors for the disease. We aimed to identify additional novel genetic variants affecting risk of NKTCL. METHODS: We did a genome-wide association study of NKTCL in multiple populations from east Asia. We recruited a discovery cohort of 700 cases with NKTCL and 7752 controls without NKTCL of Han Chinese ancestry from 19 centres in southern, central, and northern regions of China, and four independent replication samples including 717 cases and 12 650 controls. Three of these independent samples (451 cases and 5301 controls) were from eight centres in the same regions of southern, central, and northern China, and the fourth (266 cases and 7349 controls) was from 11 centres in Hong Kong, Taiwan, Singapore, and South Korea. All cases had primary NKTCL that was confirmed histopathologically, and matching with controls was based on geographical region and self-reported ancestry. Logistic regression analysis was done independently by geographical regions, followed by fixed-effect meta-analyses, to identify susceptibility loci. Bioinformatic approaches, including expression quantitative trait loci, binding motif and transcriptome analyses, and biological experiments were done to fine-map and explore the functional relevance of genome-wide association loci to the development of NKTCL. FINDINGS: Genetic data were gathered between Jan 1, 2008, and Jan 23, 2019. Meta-analysis of all samples (a total of 1417 cases and 20 402 controls) identified two novel loci significantly associated with NKTCL: IL18RAP on 2q12.1 (rs13015714; p=2·83 × 10-16; odds ratio 1·39 [95% CI 1·28-1·50]) and HLA-DRB1 on 6p21.3 (rs9271588; 9·35 × 10-26 1·53 [1·41-1·65]). Fine-mapping and experimental analyses showed that rs1420106 at the promoter of IL18RAP was highly correlated with rs13015714, and the rs1420106-A risk variant had an upregulatory effect on IL18RAP expression. Cell growth assays in two NKTCL cell lines (YT and SNK-6 cells) showed that knockdown of IL18RAP inhibited cell proliferation by cell cycle arrest in NKTCL cells. Haplotype association analysis showed that haplotype 47F-67I was associated with reduced risk of NKTCL, whereas 47Y-67L was associated with increased risk of NKTCL. These two positions are component parts of the peptide-binding pocket 7 (P7) of the HLA-DR heterodimer, suggesting that these alterations might account for the association at HLA-DRB1, independent of the previously reported HLA-DPB1 variants. INTERPRETATION: Our findings provide new insights into the development of NKTCL by showing the importance of inflammation and immune regulation through the IL18-IL18RAP axis and antigen presentation involving HLA-DRB1, which might help to identify potential therapeutic targets. Taken in combination with additional genetic and other risk factors, our results could potentially be used to stratify people at high risk of NKTCL for targeted prevention. FUNDING: Guangdong Innovative and Entrepreneurial Research Team Program, National Natural Science Foundation of China, National Program for Support of Top-Notch Young Professionals, Chang Jiang Scholars Program, Singapore Ministry of Health's National Medical Research Council, Tanoto Foundation, National Research Foundation Singapore, Chang Gung Memorial Hospital, Recruitment Program for Young Professionals of China, First Affiliated Hospital and Army Medical University, US National Institutes of Health, and US National Cancer Institute.

IL18RAP polymorphisms and its plasma levels in patients with Lumbar disc degeneration.

OBJECTIVES: Lumbar disc degeneration (LDD) is a common musculoskeletal disorder. Interleukin 18 Receptor Accessory Protein (IL18RAP) gene is involved in disc degeneration and inflammatory processes like matrix degeneration. Hence, this study was performed to understand the role of 2 IL18RAP (rs1420106 and rs917997) polymorphisms and IL18RAP plasma levels in lumbar disc degeneration (LDD) in Indian population. PATIENTS AND METHODS: 200 LDD patients and 200 healthy controls were recruited for the study. Genotyping was performed using allelic discrimination assay. IL18RAP levels were measured by ELISA. RESULTS: rs1420106 polymorphism did not follow Hardy Weinberg equilibrium, so it was not considered for association analysis. There was a significant association among females in CT genotype of rs917997 in LDD (p = 0.041). Also, among subjects with no history of alcohol consumption, CT allele was found to be significantly associated and had a protective effect (OR = 0.61). The plasma levels of IL18RAP were also measured. There was no significant difference in IL18RAP levels between patients and controls. CONCLUSION: Overall, rs917997 polymorphism did not show any significant difference between patients and controls (p = 0.77). However, it showed a protective role in females and patients with no history of alcohol consumption in Indian population and there was no association between polymorphisms and IL18RAP plasma levels.

Role of APOE and IL18RAP gene polymorphisms in cervical spondylotic myelopathy in Indian population.

Cervical spondylotic myelopathy (CSM) is a progressive degenerative spine disease. It is not clear why certain patients develop symptomatic myelopathy whereas others do not, even in the presence of radiographic features of cervical stenosis. Genetic predisposition has been suggested, supported by familial occurrence of CSM. In this study we explored the demographic and radiographic features of CSM in Indian population and studied the association between polymorphisms in interleukin18RAP and apo-lipoprotein genes in CSM. A total of 100 CSM patients and 100 healthy control subjects were included in this study. Genotyping of APOE (rs7412 and rs429358) and IL18RAP (rs1420106 and rs917997) gene polymorphisms was performed by Taqman allelic discrimination assay. Comparison of allelic frequencies, ε2 versus ε3 (OR = 4.4, 95%CI = 1.23-15.73, P = 0.002) and ε2 versus ε4 (OR = 6.67, 95%CI = 1.58-28.04, P = 0.009) showed a statistically significant association for the risk of CSM. There was no significant association between different genotypes with sex, T2 signal intensity change and Nurick grade. Only patients having multiple level cervical prolapsed intervertebral disc (PIVD) on MRI, had a higher proportion of the ε2 allele as compared to controls (p = <0.0001). No significant association was found between IL18RAP gene polymorphisms (rs1420106 and rs917997) with the risk of CSM. ε2 allele was associated with the risk of CSM in Indian population. There was no significant association between the two single nucleotide polymorphisms (SNPs) of IL18RAP gene with risk of CSM.

Neutrophils From Children With Systemic Juvenile Idiopathic Arthritis Exhibit Persistent Proinflammatory Activation Despite Long-Standing Clinically Inactive Disease.

Background: Systemic juvenile idiopathic arthritis (SJIA) is a chronic childhood arthropathy with features of autoinflammation. Early inflammatory SJIA is associated with expansion and activation of neutrophils with a sepsis-like phenotype, but neutrophil phenotypes present in longstanding and clinically inactive disease (CID) are unknown. The objective of this study was to examine activated neutrophil subsets, S100 alarmin release, and gene expression signatures in children with a spectrum of SJIA disease activity. Methods: Highly-purified neutrophils were isolated using a two-step procedure of density-gradient centrifugation followed by magnetic-bead based negative selection prior to flow cytometry or cell culture to quantify S100 protein release. Whole transcriptome gene expression profiles were compared in neutrophils from children with both active SJIA and CID. Results: Patients with SJIA and active systemic features demonstrated a higher proportion of CD16+CD62Llo neutrophil population compared to controls. This neutrophil subset was not seen in patients with CID or patients with active arthritis not exhibiting systemic features. Using imaging flow cytometry, CD16+CD62Llo neutrophils from patients with active SJIA and features of macrophage activation syndrome (MAS) had increased nuclear hypersegmentation compared to CD16+CD62L+ neutrophils. Serum levels of S100A8/A9 and S100A12 were strongly correlated with peripheral blood neutrophil counts. Neutrophils from active SJIA patients did not show enhanced resting S100 protein release; however, regardless of disease activity, neutrophils from SJIA patients did show enhanced S100A8/A9 release upon PMA stimulation compared to control neutrophils. Furthermore, whole transcriptome analysis of highly purified neutrophils from children with active SJIA identified 214 differentially expressed genes (DEG) compared to neutrophils from healthy controls. The most significantly upregulated gene pathway was Immune System Process, including AIM2, IL18RAP, and NLRC4. Interestingly, this gene set showed intermediate levels of expression in neutrophils from patients with long-standing CID yet persistent serum IL-18 elevation. Indeed, all patient samples regardless of disease activity demonstrated elevated inflammatory gene expression, including inflammasome components and S100A8. Conclusion: We identify features of neutrophil activation in SJIA patients with both active disease and CID, including a proinflammatory gene expression signature, reflecting persistent innate immune activation. Taken together, these studies expand understanding of neutrophil function in chronic autoinflammatory disorders such as SJIA.

Are IL18RAP gene polymorphisms associated with body mass regulation? A cross-sectional study.

OBJECTIVES: To investigate the association between IL18RAP and body mass index (BMI) and obesity and to verify the effect of a polymorphism in the microRNA136 (MIR136) IL18RAP binding region. DESIGN: We analysed samples from two Spanish cross-sectional studies, VALCAR (Spanish Mediterranean coast) and Hortega (Spanish centre). These studies aimed at analysing cardiovascular risk and development of cardiovascular disease in the general population. Both populations correspond to regions with different characteristics. SETTING: Five IL18RAP single nucleotide polymorphisms were selected using the SYSNPs web tool and analysed by oligonucleotide ligation assay (SNPlex). For the MIR136 functional study, cells were transfected with plasmids containing different rs7559479 polymorphism alleles and analysed by luciferase reporter assays. PARTICIPANTS: 1970 individuals (Caucasian, both genders): VALCAR (468) and Hortega (1502). RESULTS: rs2293225, rs2272127 and rs7559479 showed the following associations: rs7559479 G allele correlated with a higher obesity risk (P=0.01; OR=1.82; 95% CI 1.15 to 2.87 for the VALCAR group; P=0.033; OR=1.35; 95% CI 1.03 to 1.79 for the Hortega population) and higher body mass index (BMI) values (P=0.0045; P=0.1 for VALCAR and Hortega, respectively); a significant association with obesity (P=0.0024, OR=1.44, 95% CI 1.14 to 1.82) and increased BMI values (P=0.008) was found when considering both populations together. rs2293225 T allele was associated with lower obesity risk (P=0.036; OR=0.60; 95% CI 0.35 to 0.96) and lower BMI values (P=0.0038; OR=1.41) while the rs2272127 G allele was associated with lower obesity risk (P=0.028; OR=0.66; 95% CI 0.44 to 0.97) only in the VALCAR population. A reporter assay showed that the presence of the A allele in rs7559479 was associated with increased MIR136 binding to IL18RAP. CONCLUSIONS: Our results suggest that polymorphisms in IL18RAP influence susceptibility to obesity. We demonstrated that the A allele in rs7559479 increases MIR136 binding, which regulates IL-18 system activity.

Genetic variants alter T-bet binding and gene expression in mucosal inflammatory disease.

The polarization of CD4+ T cells into distinct T helper cell lineages is essential for protective immunity against infection, but aberrant T cell polarization can cause autoimmunity. The transcription factor T-bet (TBX21) specifies the Th1 lineage and represses alternative T cell fates. Genome-wide association studies have identified single nucleotide polymorphisms (SNPs) that may be causative for autoimmune diseases. The majority of these polymorphisms are located within non-coding distal regulatory elements. It is considered that these genetic variants contribute to disease by altering the binding of regulatory proteins and thus gene expression, but whether these variants alter the binding of lineage-specifying transcription factors has not been determined. Here, we show that SNPs associated with the mucosal inflammatory diseases Crohn's disease, ulcerative colitis (UC) and celiac disease, but not rheumatoid arthritis or psoriasis, are enriched at T-bet binding sites. Furthermore, we identify disease-associated variants that alter T-bet binding in vitro and in vivo. ChIP-seq for T-bet in individuals heterozygous for the celiac disease-associated SNPs rs1465321 and rs2058622 and the IBD-associated SNPs rs1551398 and rs1551399, reveals decreased binding to the minor disease-associated alleles. Furthermore, we show that rs1465321 is an expression quantitative trait locus (eQTL) for the neighboring gene IL18RAP, with decreased T-bet binding associated with decreased expression of this gene. These results suggest that genetic polymorphisms may predispose individuals to mucosal autoimmune disease through alterations in T-bet binding. Other disease-associated variants may similarly act by modulating the binding of lineage-specifying transcription factors in a tissue-selective and disease-specific manner.

Inflammatory and anti-inflammatory cytokines in the seminal plasma of infertile men suffering from varicocele.

Varicocele is one of causes of the declined sperm quality and low sperm production, which can lead to infertility in males. There are several experimental and epidemiological findings which support the idea that inflammatory mechanisms play an essential role in varicocele pathogenesis. Besides, in this pathological state, interleukin-37 (IL-37) as an anti-inflammatory cytokine is able to bind interleukin-18-binding protein (IL-18BP), and subsequently binds IL-18 receptor ß, inhibiting the pro-inflammatory activity of IL-18. To explore the interaction between IL-37 and IL-18 in infertility, we measured the amount of these cytokines in the seminal fluid of infertile men affected by varicocele. The seminal plasma levels of IL-37 and IL-18 were measured in 75 infertile men with varicocele and 75 healthy fertile controls (age range, 30-48 years) using enzyme-linked immunosorbent assay. The seminal levels of IL-37 and IL-18 were significantly increased in infertile men with varicocele when compared to fertile controls (p < .0001). Because of the essential role(s) of cytokines in inflammatory response of cell systems, it could be possible that sperm motility is reduced following increased IL-18, activated neutrophils and reactive oxygen species in semen of infertile patients with varicocele. Moreover, the results of this study indicated that interaction between IL-37 and IL-18Rß can lead to reduced inflammatory responses. It seems that IL-37 might be a potential biomarker and therapeutic target for male infertility.

Genetic analysis of innate immunity in Behcet's disease identifies an association with IL-37 and IL-18RAP.

Interleukin-1 (IL-1) and the IL-1 receptor (IL-1R) family play an important role in the pathogenesis of inflammatory diseases. This study aimed to investigate the association between single nucleotide polymorphisms (SNP) of IL-1 and IL-1R family genes with Vogt-Koyanagi-Harada (VKH) and Behcet's disease (BD) in Han Chinese. The case-control study was divided into two stages and included 419 VKH cases, 1063 BD cases and 1872 healthy controls. The MassARRAY platform (Sequenom), iPLEX Gold Assay and TaqMan SNP assays were used to score genotypes of 24 SNPs. The expression of IL-37 and IL-18Rap was measured by ELISA and real-time PCR in genotyped healthy individuals. A significantly lower frequency of the AG genotype, and a higher frequency of the GG genotype and G allele of IL-37/rs3811047 were observed in BD as compared to controls. AA genotype and A allele frequency of IL-18RAP/rs2058660 was significantly decreased in BD as compared to controls. Functional studies performed in healthy controls showed that rs3811047 AG genotype carriers had a higher IL-37 gene expression in peripheral blood mononuclear cells (PBMCs) than GG carriers. GG carriers showed a higher cytokine expression as compared to AG carriers. No association was detected between the tested SNPs and VKH.

Potential involvement of the interleukin-18 pathway in schizophrenia.

OBJECTIVE: Accumulating evidence implicates inflammatory cytokines in the development of psychiatric disorders, including schizophrenia (SZ). IL-18 is one of cytokines that plays a crucial role in immune response and neurodevelopment. We aimed to investigate potential genetic alterations of the cytokine system underpinning SZ. METHODS: We tested the association of genetic variants within the cytokine-cytokine receptor interaction (CCRI) pathway with SZ, using GWAS-derived data involving 768 adult SZ patients and 1348 controls, and replicated the association of IL18R1 rs1035130 with SZ in an independent sample of 1957 adult patients and 1509 controls. We compared expression levels of IL18, IL18R1 and IL18RAP in peripheral blood of a cohort of adolescent participants (<18 years), including 14 early-onset SZ patients and 13 healthy controls. Furthermore, we carried out a cis-eQTL (expression Quantitative Trait Loci) and a cis-mQTL (Methylation Quantitative Trait Loci) analysis for IL18R1 rs1035130. RESULTS: In the discovery stage, we detected association signals within two IL18 pathway genes, IL18R1 and IL18RAP, with the most significant marker being IL18R1 rs1035130 (P = 1.84E-7, OR = 0.70). In the validation stage, we found rs1035130 was associated with SZ (P = 0.028, OR = 0.89). Expressions of IL18 and IL18R1 were altered in blood of SZ patients compared with 13 controls. Furthermore, cis-QTL analyses indicated that rs1035130 was associated with an eQTL and 5 mQTLs. CONCLUSION: Our findings suggest the alteration of IL18 pathway may contribute to the psychopathology of SZ.

Polymorphisms of ST2-IL18R1-IL18RAP gene cluster: a new risk for autoimmune thyroid diseases.

Interleukin 33 (IL33) / ST2 pathway and ST2-interlukin18 receptor1-interlukin18 receptor accessory protein (ST2-IL18R1-IL18RAP) gene cluster have been involved in many autoimmune diseases but few report in autoimmune thyroid diseases (AITD). In this study, we investigated whether polymorphisms of IL33, ST2, IL18R1, and IL18RAP are associated with Graves' disease (GD) and Hashimoto's thyroiditis (HT), two major forms of AITD, among a Chinese population. A total of 11 SNPs were explored in a case-control study including 417 patients with GD, 250 HT patients and 301 controls, including rs1929992, rs10975519, rs10208293, rs6543116, rs1041973, rs3732127, rs11465597, rs1035130, rs2293225, rs1035127, rs917997 of IL 33, ST2-IL18R1-IL18RAP gene cluster. Genotyping of these SNPs was performed using matrix-assisted laser desorption / ionization-time-of-flight mass spectrometer (MALDI-TOF-MS) platform from Sequenom. The frequencies of allele A and AA+AG genotype of rs6543116 (ST2) in HT patients were significantly increased compared with those of the controls (P = 0.029/0.021, OR = 1.31/1.62). And in another SNP rs917997, AA+AG genotype presented an increased frequency in HT subjects compared with controls (P = 0.046, OR = 1.53). Furthermore, the haplotype GAGCCCG from ST2-IL18R1-IL18RAP gene cluster (rs6543116, rs1041973, rs1035130, rs3732127, rs1035127, rs2293225, rs917997) was associated with increased susceptibility to GD with an OR of 2.03 (P = 0.022, 95% CI = 1.07-3.86). Some SNPs of ST2-IL18R1-IL18RAP gene cluster might increase the risk of susceptibility of HT and GD in Chinese Han population.

Association of genetic polymorphisms of interleukins with gastric cancer and precancerous gastric lesions in a high-risk Chinese population.

Helicobacter pylori (H. pylori) infection and cytokine-mediated inflammatory responses play important roles in gastric cancer (GC) pathogenesis. To investigate an association between genetic polymorphisms in interleukin (IL)-1ß, IL-4R, IL-8, IL-10, IL-16, IL-18RAP, IL-22, and IL-32 and risks of GC and its precursors, a population-based study was conducted in Linqu County. Genotypes were determined by Sequenom MassARRAY platform in 132 GC cases and 1198 subjects with gastric lesions. The H. pylori status was determined by (13)C-urea breath test ((13)C-UBT) or enzyme-linked immunosorbent assay (ELISA). Among 11 candidate single nucleotide polymorphisms (SNPs), subjects carrying IL-18RAP rs917997 AA genotype were associated with risk of GC [adjusted odds ratio (OR) = 1.83, 95 % confidence interval (CI) 1.14-2.92] or chronic atrophic gastritis (CAG; OR = 1.55, 95 % CI 1.07-2.24). The risk of GC was also increased in subjects carrying IL-32 rs2015620 A allele (AA + AT; OR = 1.92, 95 % CI 1.09-3.39). Moreover, elevated risks of CAG (OR = 2.64, 95 % CI 1.89-3.69), intestinal metaplasia (IM; OR = 5.58, 95 % CI 3.86-8.05), and dysplasia (DYS; OR = 1.64, 95 % CI 1.18-2.26) were observed in subjects with IL-22 rs1179251 CC genotype. Stratified analysis indicated that risks of GC and its precursors were elevated in subjects with IL-32 rs2015620 A allele (AA + AT) or IL-22 rs1179251 CC genotype and H. pylori infection, and significant interactions between these two SNPs and H. pylori infection were found. These findings suggested that IL-18RAP rs917997, IL-32 rs2015620, IL-22 rs1179251, and interactions between these polymorphisms and H. pylori infection were associated with risks of gastric lesions. Genetic polymorphisms of interleukins may play crucial roles in H. pylori-induced gastric carcinogenesis.