Interleukin-4 Gene Polymorphisms Confer Behçet’s Disease in Turkish Population

Inflammatory status might direct ILC and NK cells to IL-17 expressing ILC3 and NK subsets in Behcet's disease

Innate lymphoid cells (ILCs) are lymphoid cells that have important effector and regulatory functions in innate immunity and tissue remodeling. Uncontrolled activation and proliferation of ILCs can contribute to inflammatory autoimmune diseases. Behcet's disease (BD) is a complex systemic inflammatory disorder of unknown etiology. It has been shown that natural killer (NK) cells may play an immunoregulatory role in BD, however the role of ILCs is unknown. In this study, the levels and functions of ILCs and NK cell subsets in BD patients were investigated. Cell surface and cytotoxic granules (perforin and granzyme) expression of NK cells and ILCs were evaluated and labeled according to whole blood lysing protocol in peripheral blood samples obtained from the patients and healthy subjects. Cytokine levels of NK cells were investigated in stimulated peripheral blood mononuclear cells. All data were analyzed by flow cytometry. Total ILC and ILC3⁺ cells were increased in active BD patients compared to inactive BD patients and healthy subjects. There was no significant difference between the patients and healthy subjects regarding NK cell surface and intracellular molecule expression. Although, an increase in IFN-γ and IL-17, and a decrease in IL-4 levels were observed in CD56^dim NK cell subset of BD patients. Recent studies showed increased neutrophilic infiltration and IL-17 secreting Th17 cells in BD patients. It is known that ILC3⁺cells are similar to Th17 subset regarding their cytokine profile and transcription factor expression patterns. Results of current study may suggest that inflammatory microenvironment in BD patients might direct ILC cells to differentiate into ILC3⁺ subset, and IL-17 released by NK cells might have a role in neutrophilic infiltration.

Serum IL-4, IL-12, IL-13, IL-27, and IL-33 levels in active and inactive ocular Behcet's disease

PURPOSE

To investigate serum levels of interleukin (IL)-12 (Th1 cytokine), IL-27 (an immunomodulatory cytokine), IL-4 (suppressor of Th1-cell growth), IL-13 (a stimulatory signal for Th2 cytokines), and IL-33 (an epithelial cell-derived cytokine) and their relations with the disease activity in Behcet's Disease (BD).

METHODS

Four groups, each composed of 20 participants were enrolled in the study; active ocular BD (Group-A), ocular BD in remission (Group-B), nonocular BD in remission (Group-C) and healthy controls (Group-D). IL levels were compared between the study groups and their correlation with the disease activity parameters were analyzed.

RESULTS

IL-13 and IL-33 were higher in Group-A. IL-27 was lower in all BD groups. Additionally, IL-13 and IL-33 levels were positively correlated with disease activity parameters.

CONCLUSION

These findings show Th2 dominance in the active phase of BD. Besides, decreased levels of IL-27, and presumably, its protective anti-inflammatory effect in all study groups may exert a new pathologic finding in BD.

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.

Association of MMP-9 gene polymorphisms with Behçet's disease risk

The human matrix metalloproteinases (MMPs) are importantly involved in aneurysm formation. Since the clinical manifestations in Behçet disease (BD) include aneurysm formation among major symptoms, polymorphisms in MMP-9 might be associated with BD susceptibility. The aim of the current case-control study was to investigate the association of four single nucleotide polymorphisms (SNPs) in MMP-9 gene: -1562 C/T, 2003 G/A (R668Q), 836 A/G (Q279R) and 1721 C/G (R574P) with BD risk in the Tunisian population. The distribution of MMP-9 gene polymorphisms was analyzed by polymerase chain-reaction (PCR) and restriction fragment length polymorphism (RFLP) for 240 BD patients and 288 controls. Our study indicated that the MMP-9 -1562 C/T polymorphism (rs3918242) was not associated with BD risk. We found a significant association of the MMP-9 2003 G/A (rs17577) with an increased susceptibility to BD. However, the MMP-9 1721 C/G polymorphism (rs2250889) had a protective role against the development of BD. Subgroup analysis based on stratification by gender revealed that the MMP-9 2003 G/A polymorphism was associated with a highly significant BD risk in women's group (G vs. A: P=0.0000001). However, the MMP-9 836 A/G polymorphism had a protective role in men's group (G vs. A: P=0.00043). The MMP-9 1721 C/G polymorphism was associated with a protective effect in both men and women groups (CG+GG vs. CC: P=0.04 and P=0.0002, respectively). The haplotype analysis did not show any association with BD risk. A significant difference in the MMP-9 serum levels were observed in the patient subgroup with ocular lesions manifestations.

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.

The role of IL-4 gene 70 bp VNTR and ACE gene I/D variants in Familial Mediterranean fever

Familial Mediterranean fever (FMF) is characterized by recurrent attacks of fever and inflammation in the peritoneum, synovium, or pleura, accompanied by pain. It is an autosomal recessive disease caused by mutations in the MEFV (MEditerranean FeVer) gene. Patients with similar genotypes exhibit phenotypic diversity. As a result, the variations in different genes could be responsible for the clinical findings of this disease. In previous studies genes encoding Angiotensin-Converting Enzyme (ACE) and IL-4 (Interleukin-4) were found to be associated with rheumatologic and autoimmune diseases. In the present study we hypothesized whether ACE I/D or IL-4 70 bp variable tandem repeats (VNTR) genes are associated with FMF and its clinical findings in Turkish patients. Genomic DNA obtained from 670 persons (339 patients with FMF and 331 healthy controls) was used in the study. Genotypes for an ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR were determined by polymerase chain reaction with specific primers. To our knowledge, this is the first study examining ACE gene I/D polymorphism and IL-4 gene 70 bp VNTR polymorphism in FMF patients. As a result, there was a statistically significant difference between the groups with respect to genotype distribution (p<0.001). According to our results, ACE gene DD genotype was associated with an increased risk in FMF [p<0.001; OR (95%): 7.715 (4.503-13.22)]. When we examined ACE genotype frequencies according to the clinical characteristics, we found a statistically significant association between DD+ID genotype and fever (p=0.04). In addition IL-4 gene P1P1 genotype was associated with FMF (p<0.001). We propose that D allele or DD genotype of ACE gene and P1 allele or P1P1 genotype of IL-4 gene may be important molecular markers for susceptibility of FMF.

Association between interleukin 4 gene intron 3 VNTR polymorphism and recurrent aphthous stomatitis in a cohort of Turkish patients

OBJECTIVE

Recurrent aphthous stomatitis (RAS) is one of the most common oral mucosal diseases, with a multifactorial etiopathogenesis, an interaction between predisposing factors and/or systemic conditions and immunological components in genetically predisposed subjects. Although there is no clear genetic mode of inheritance, there is evidence that inheritance of specific gene polymorphisms may predispose individuals to RAS. The purpose of the present study was to investigate a possible association between the functional interleukin 4 (IL4) VNTR genetic polymorphism and RAS in a sample of Turkish patients.

METHODS

The study included 145 unrelated patients with a clinical diagnosis of RAS and 150 unrelated healthy controls. Genomic DNA was isolated and IL4 gene 70 bp VNTR polymorphism determined by using polymerase chain reaction (PCR) with specific primers.

RESULTS

The distribution of genotype and allele frequencies of IL4 gene intron 3 VNTR polymorphism was statistically different between RAS patients and control group (p<0.0001 and p<0.0001, respectively) P2P2 genotype and P2 allele were also found to be protective with a lower risk for susceptibility to RAS (p<0.0001).

CONCLUSION

The results of this study suggest that intron 3 VNTR polymorphism in the IL4 gene is associated with RAS susceptibility in Turkish population.

Identification of a susceptibility locus in STAT4 for Behçet's disease in Han Chinese in a genome-wide association study

OBJECTIVE

To identify susceptibility loci for Behçet's disease (BD) and elucidate their functional role.

METHODS

A genome-wide association study (GWAS) and functional studies were conducted. A total of 149 patients and 951 controls were enrolled in the initial GWAS, and 554 patients and 1,159 controls were enrolled in the replication study. Real-time polymerase chain reaction, luciferase reporter assay, and enzyme-linked immunosorbent assay were performed.

RESULTS

Our GWAS and replication studies identified a susceptibility locus around STAT4 (single-nucleotide polymorphisms [SNPs] rs7574070, rs7572482, and rs897200; P = 3.36 × 10(-7) to 6.20 × 10(-9) ). Increased expression of STAT4 was observed in individuals carrying the rs897200 risk genotype AA. Consistent with the idea that STAT4 regulates the production of interleukin-17 (IL-17) and interferon-γ, IL17 messenger RNA and protein levels were increased in individuals carrying the rs897200 risk genotype AA. Interestingly, the risk allele A of rs897200 creates a putative transcription factor binding site. To test whether it directly affects STAT4 transcription, an in vitro luciferase reporter gene assay was performed. Higher transcription activity was observed in individuals carrying the risk allele A, suggesting that rs897200 is likely to directly affect STAT4 expression. Additionally, 2 SNPs, rs7574070 and rs7572482, which are tightly linked with rs897200, were cis-expression quantitative trait loci (eQTL) SNPs, suggesting that SNP rs897200 is an eQTL SNP. Most importantly, the clinical disease severity score was higher in individuals with the rs897200 risk genotype AA.

CONCLUSION

These findings strongly suggest that STAT4 is a novel locus underlying BD. We propose a model in which up-regulation of STAT4 expression and subsequent STAT4-driven production of inflammatory cytokines, such as IL-17, constitute a potential pathway leading to BD.

Interleukin-2 gene polymorphism in Turkish patients with Behçet's disease and its association with ocular involvement

Behçet's disease (BD) is a chronic immune-mediated systemic disease, characterized by oral and genital lesions and ocular inflammation. Several cytokine genes may play crucial roles in host susceptibility to BD, because the cytokine production capacity varies among individuals and depends on the cytokine gene polymorphisms. The association of the interleukin (IL)-2 gene polymorphisms with the susceptibility to BD was investigated in this study. DNA samples were obtained from a Turkish population of 97 patients with BD and 76 healthy control subjects. Polymorphisms of IL-2 gene at position -330 and +166 were determined using the polymerase chain reaction with sequence-specific primers. In the patients with BD, there was a significantly increased frequency of IL-2 -330 GT genotype. Interestingly, we demonstrated that the frequencies of IL-2 -330 GT and IL-2 + 166 GG genotypes were increased in BD patients with ocular involvement, whilst IL-2 -330 TT genotype was significantly decreased. Also, analysis of allele frequency demonstrated that the presence of G allele at position +166 of IL-2 seems to be a risk factor for ocular involvement. These results reveal that IL-2 -330 GT genotype may be a susceptibility factor for BD, whereas IL-2 -330 TT genotype seems to display a protective association with BD. Additionally, IL-2 gene polymorphisms might be associated with ocular involvement in BD.

Polymorphisms in the IL-13 and IL-4R genes are associated with the development of renal cell carcinoma

BACKGROUND

Cytokines are the important modulators that bind to their relevant receptors in response to some stimuli to mediate the homeostasis. It has been suggested that the imbalance of immune system of the host might affect the generation of diseases, including cancers.

PATIENTS AND METHODS

We investigated the association between six functional polymorphisms of IL-4, IL-13, and IL-4R genes and susceptibility to renal cell cancer in a hospital-based study, including 620 renal cell carcinoma (RCC) patients and 623 controls. Logistic regression model was used to assess the genetic effects on the development of RCC.

RESULTS

Overall, individuals with IL-4R Ile50Val CT/TT genotypes had a 0.34-fold significantly decreased RCC risk (CT/TT versus CC), and the T variant allele was associated with a decreased risk of RCC in a dose-response manner (Ptrend=0.009). In addition, we also observed that IL-13 C-1055T and Arg130Gln polymorphisms could decrease the risk of RCC [TT versus

CC/CT

odds ratio=0.36, 95% confidence interval (CI)=0.16-0.78; AA versus GG/GA: 0.66, 0.44-0.97, respectively]. Furthermore, a multiplicative interaction association between the combined IL-4R Ile50Val and IL-13 C-1055T genotypes was observed to decrease the risk of RCC (P=0.036).

CONCLUSION

IL-13 and IL-4R may play an important role in the etiology of RCC.