IL18 polymorphism is associated with Behçet's disease but not lupus in patients from Turkey

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)

Genetics and immunodysfunction underlying Behçet's disease and immunomodulant treatment approaches

Behçet's disease (BD) is a chronic autoimmune condition primarily prevalent in populations along the Mediterranean Sea. The exact etiology of BD has not been fully explained yet, but the disease occurrence is associated with a genetic factor, human leukocyte antigen (HLA)-B51 antigen. Among the various immunodysfunctions that are found in BD, patients are increased neutrophil motility and superoxide production, as well as elevated production of tumor necrosis factor (TNF)-α and decreased production of interleukin (IL)-10. Elevated levels of inflammatory cytokines like IL-1 and IL-17 in BD have been found associated with aberrant expression of microRNA. Gene polymorphisms in BD patients have been observed in molecules involved in responses to pathogens that can ultimately modulate the host antimicrobial response. Moreover, several single nucleotide polymorphisms (SNPs) have been reported in genes encoding chemokines and adhesion molecules; many of these changes manifest as increases in vascular inflammation and vascular damage. Lastly, genetic and epigenetic changes have been suggested as involved in the pathogenesis of BD. Modifications in DNA methylation have been found in BD patient monocytes and lymphocytes, leading to adverse function of these cells. This review presents a comprehensive compilation of the literature with regard to the immunodysfunction underlying BD, as well as of the genetics, newly described clinical specifications and novel treatment strategies using immunomodulants based on the current understanding of BD.

Cytokine, C-Reactive Protein, and Heat Shock Protein mRNA Expression Levels in Patients with Active Behçet's Uveitis

Background

To investigate the gene expression levels of interleukin 10 (IL10), IL18, interferon gamma (IFNG), IFN-gamma receptor (IFNGR), C-reactive protein (CRP), and heat shock protein 70 (HSP70) in patients with active Behçet’s uveitis.

Material/Methods

Forty patients with Behçet’s disease diagnosed according to the International Study Group criteria and 30 healthy individuals were included in the study. IL10, IL18, IFNG, IFNGR, CRP, and HSP70 gene expression levels were compared.

Results

Expression levels of IL18, IFNG, IFNGR, and CRP were significantly higher in patients with active Behçet’s uveitis than in control subjects (P<0.01 for all), whereas no significant differences were found in IL10 and HSP70 gene expression levels (P>0.01 for both).

Conclusions

IL18, IFNG, IFNGR, and CRP gene expression is significantly increased in active Behçet’s uveitis. There was no significant difference between active Behçet’s uveitis patients and controls in terms of IL10 and HSP70 gene expression levels. We conclude that drugs prescribed to Behçet’s patients with active uveitis downregulate gene expression.

Association of cytokine gene polymorphisms (IL‑6, IL‑12B, IL‑18) with Behcet's disease : A meta-analysis

PURPOSE

This study aims to investigate the association of cytokine gene polymorphisms with the risk of Behcet's disease (BD) via comprehensive meta-analysis.

METHODS

The Embase and PubMed databases covering the period from the earliest possible year to May 2015 were searched. A total of 13 eligible articles including 2,065 BD patients and 1,559 controls were recruited. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to assess the strength of the associations. Potential publication bias was evaluated using Egger's linear regression test.

RESULTS

Meta-analysis indicated associations between IL‑6 rs1800795, IL‑12B rs3212227, and IL‑18 rs1946518 in all study subjects: IL‑18 rs1946518 in the dominant model (IL‑18 rs1946518: OR = 0.48, 95 % CI: 0.34-0.70, P = 0.000) and the homozygote model (IL‑18 rs1946518: OR = 0.40, 95 % CI: 0.25-0.65, P = 0.000); and IL‑6 rs1800795 and IL‑12B rs3212227 in the dominant model (IL‑6 rs1800795: OR = 0.53, 95 % CI: 0.39-0.72, P = 0.000; IL‑12B rs3212227: OR = 1.26, 95 % CI: 1.06-1.48, P = 0.007; IL‑18 rs1946518: OR = 0.46, 95 % CI: 0.33-0.65, P = 0.000). No significant evidence for associations of IL‑18 rs187238 polymorphisms with BD susceptibility was detected.

CONCLUSION

In summary, this meta-analysis finds that IL‑6 rs1800795 and IL‑18 rs1946518 polymorphisms decrease the risk of BD. However, IL‑12B rs3212227 increases BD susceptibility. Further large-scale investigation of this association is necessary.

Molecular Genetic Advances in Uveitis

Uveitis is usually considered as an intraocular inflammation characterized by variety of clinical features. Behcet's disease (BD), Vogt-Koyanagi-Harada (VKH) syndrome, acute anterior uveitis (AAU), and birdshot chorioretinopathy (BCR) are examples of noninfectious forms of uveitis. Although the precise pathogenesis remains unclear, accumulating evidence shows that complex genetic backgrounds coupled with an aberrant immune response may be implicated in the development of uveitis. The complement and pattern recognition systems are both important factors of the innate immune system and are involved in the pathogenesis of uveitis. Copy number variants (CNVs) of complement component 4 have been found to be associated with BD and VKH syndrome, but not with AAU. Several CNVs and gene polymorphisms of toll-like receptors were found to be associated with BD. Leukocytes are an important part of the adaptive immune system and various molecules on these cells play an important role in the development of uveitis. Genes encoding for human leukocyte antigens (HLAs) have been shown to be associated with certain uveitis entities, including BD (HLA-B51), VKH syndrome (HLA-DR4, DRB1/DQA1), AAU (HLA-B27), and BCR (HLA-A29). Genome wide association studies showed that the IL-23R locus was a shared risk factor for multiple uveitis entities including BD, AAU, and VKH syndrome. In addition, various other non-HLA genes are also associated with BD or VKH syndrome, such as IL-10, STAT4, STAT3, and UBAC2. These studies support the hypothesis that genetic factors play a key role in the pathogenesis of uveitis.

Ethnicity-stratified analysis of the association between IL-18 polymorphisms and systemic lupus erythematosus in a European population: a meta-analysis

We performed a meta-analysis to identify the association between polymorphisms in the promoter of interleukin-18 (IL-18) and susceptibility for systemic lupus erythematosus (SLE) . Genotype data for three single-nucleotide polymorphisms (SNPs rs360719, rs1946518, and rs187238) in the IL-18 promoter were extracted from 20 studies of three different ethnicities (European, Asian, and South American). Data from each ethnicity group and their combinations were analyzed. We found distinct evidence of an association between rs360719 and SLE (P = 0.001) in the European/South American group [odds ratio (OR) 1.31 per C allele, 95% confidence interval (CI) 1.11-1.53]. Stratification analysis by ethnicity showed a significant association between rs360719 and SLE in the European population (OR 1.33 per C allele, 95% CI 1.11-1.61, P = 0.003) and a lesser effect in the same direction in the South American population (OR 1.18). A significant association was also identified between rs1946518 and SLE in the European population (OR 1.16 per A allele, 95% CI 1.03-1.30, P = 0.017), although there was no association in the Asian or the combined European/Asian population. We also examined genome-wide association study (GWAS) data from an Asian subpopulation (Chinese) for the association between rs1946518 and SLE, but found no association (P = 0.83). The third SNP, rs187238, was not significantly associated with SLE in any of the populations examined. In summary, this study identified a significant association between SLE and two SNPs within the IL-18 gene promoter region (rs360719 and rs1946518) in a European population, but not in populations of Asian origin.

IL-18 gene polymorphisms in aphthous stomatitis vs. Behçet's disease in a cohort of Egyptian patients

OBJECTIVE

A clinical investigation of the potential correlation of two single-nucleotide polymorphisms at -137 (G/C) and -607 (C/A) in the promoter region of the IL-18 gene, with the susceptibility to aphthous stomatitis and Behçet's disease.

PATIENT AND METHODS

This study included 80 aphthous stomatitis patients and 80 patients with Behçet's disease. Eighty healthy subjects were enrolled as a control group. IL-18 single-nucleotide polymorphisms at -607 and -137 regions were analyzed using polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

The genotype and allele distributions of the two regions did not differ significantly between patients with aphthous stomatitis and controls. The genotype and allele distributions at -607 were significantly different between patients with Behçet's disease [CC (P = 0.044), C allele (P = 0.043), A allele (P = 0.043)], and controls. The frequency of the GG genotype at position -137 in patients with Behçet's disease was associated only with a higher rate of ocular manifestations (OR= 1.4, CI= 0.76-2.7, P = 0.031).

CONCLUSION

IL-18 gene polymorphisms were not associated with any susceptibility to aphthous stomatitis, while a positive association was found with patients with Behçet's disease regarding -607 promoter site. Moreover, patients with Behçet's disease carrying the GG genotype at position -137 had a higher risk of developing ocular manifestations.

Association of interleukin-18 (-137G/C) polymorphism with rheumatoid arthritis and systemic lupus erythematosus: a meta-analysis

BACKGROUND

Recent studies have suggested that interleukin (IL)-18 gene (-137G/C) polymorphism is associated with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). However, other studies did not confirm this correlation.

OBJECTIVE

The objective of this study was to evaluate the relationships of IL-18 -137G/C and RA and SLE using a meta-analysis.

METHODS

Pubmed, Embase and Cochrane library databases were systemically searched. Data were extracted by two independent reviewers and pooled odds ratio (OR) with 95% confidence interval (CI) was calculated.

RESULTS

In RA, the overall ORs and 95% CIs of -137C were 1.03, 0.88-1.22 (p=0.391); 1.22, 0.89-1.68 (p=0.020) and 1.06, 0.93-1.21 (p=0.110) in dominant, recessive, and additive models, respectively. Furthermore, in SLE, the overall ORs and 95% CIs of -137C were 1.10, 0.94-1.29 (p=0.980); 1.21, 0.91-1.60 (p=0.010) and 1.10, 0.97-1.24 (p=0.454) in dominant, recessive, and additive models, respectively. IL-18 -137G/C could increase the risk of RA and SLE. No publication bias was found in this meta-analysis. After population stratification analysis, under recessive model, the pooled ORs and 95% CIs of -137C were 1.14, 0.82-1.60 (p=0.008) and 1.01, 0.66-1.55 (p=0.004) in European RA patients and Asian SLE patients, respectively.

CONCLUSIONS

This meta-analysis showed that IL-18 -137G/C was a risk factor for RA and SLE, especially for RA in Europeans and SLE in Asians.

Association of macrophage migration inhibitory factor gene polymorphisms with Behçet's disease in a Han Chinese population

OBJECTIVE

To examine whether polymorphisms of the macrophage migration inhibitory factor (MIF) gene are associated with Behçet's disease (BD) in a Han Chinese population.

DESIGN

Case-control study.

PARTICIPANTS

A total of 600 patients with BD and 600 age-, sex-, and ethnically matched healthy controls were enrolled.

METHODS

Two single nucleotide polymorphisms (SNPs), rs755622 and rs2096525, were genotyped using a polymerase chain reaction (PCR) restriction fragment length polymorphism assay. Allele and genotype frequencies were compared between patients and controls using the chi-square test. The expression of MIF was examined by real-time PCR.

MAIN OUTCOME MEASURES

Association of SNPs in MIF with BD.

RESULTS

Significantly decreased frequencies of the rs755622 genotype GG and G allele were found in patients with BD compared with controls. The frequencies of the genotype TT and T allele of the SNP rs2096525 were significantly lower in patients with BD compared with controls. Stratification analysis showed that the frequencies of rs755622 genotype GG in the oral aphthae, genital ulceration, or hypopyon subgroups were significantly decreased compared with controls (all P(c) < 0.05). A significantly lower frequency of the G allele of rs755622 was observed in the oral aphthae, genital ulceration, hypopyon, and arthritis subgroups compared with controls (P(c) < 0.05). The frequencies of the rs2096525 genotype TT and T alleles were also decreased in the oral aphthae, genital ulceration, hypopyon, and skin lesion subgroups compared with the controls (P(c) < 0.01). The results also showed that the expression of MIF mRNA in individuals carrying the CC genotype of rs755622 was 1.78- and 1.92-fold higher than in those carrying the GC or GG genotype.

CONCLUSIONS

This study identified a strong association of the 2 SNPs, rs755622 and rs2096525, in the MIF gene with BD and suggests that the involvement of MIF in BD may be through regulation of its mRNA expression.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

New insights into the pathogenesis of Behçet's disease

Behçet's disease (BD) is a recurrent systemic inflammatory disorder of unknown origin characterized by oral and genital mucous ulcer, uveitis, and skin lesions. Involvement of large vessels, central nervous system (CNS), gastrointestinal tract and thrombotic events are less frequent but can be life threatening. The aim of this review is to provide new insights into the pathogenesis of BD. Over the past year substantial advances have been done in the understanding of the genetic [1,2] and immunology [3] of BD. BD is at the crossroad between autoimmune and autoinflammatory syndromes. In common with autoimmune diseases BD shares class I MHC association. However, in contrast to autoimmune disorders, BD has clinical features that seem to be mostly autoinflammatory. The pathogenesis of BD is still unknown, but major determinants of the genetic and immune system abnormalities have been reported recently. Triggering infectious factors are supposed to participate in the outbreak of BD in genetically predisposed patients. Two recent large genome-wide association study (GWAS) conducted in Turkey and Japan reported association between single nucleotide polymorphism (SNP) of interleukin (IL)-10 and IL-23R/IL-12RB2 genes and BD. New insights into the perturbations of T cell homeostasis of BD recently emerged. We have recently demonstrated the promotion of Th17 responses and the suppression of regulatory T cells (Tregs) that were driven by interleukin (IL)-21 production and that correlates with BD activity. Inflammatory cells within BD inflammatory lesions included mostly neutrophils, Th1 and Th17 cells, and cytotoxic CD8+ and γδ T cells. Altogether, the recent progresses in the knowledge of BD pathogenesis pave the way for innovative therapy.