A Single Nucleotide Polymorphism in the FOXP3 Gene Associated with Behçet's Disease in an Iranian Population

Baculoviral inhibitor of apoptosis family of proteins repeat-containing 5 gene methylation status in peripheral blood mononuclear cells and plasma survivin levels in patients with Behçet's disease

Objectives

This study aims to evaluate the baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) gene methylation in the peripheral blood mononuclear cells (PBMCs) in patients with Behçet’s disease (BD) compared to healthy controls and the association of survivin with BD activity.

Patients and methods

A cross-sectional study was conducted on 43 BD patients (22 males, 21 females; mean age 36.6±10.1 years; range, 18 to 66 years) and 44 age- and sex-matched healthy controls (23 males, 21 females; mean age 35.4±7.5 years; range, 18 to 61 years) between August 2019 and December 2019. Sample size was calculated guided by taking into account the difference of 1.5 units between the mean expression of BIRC5 gene in the BD and control groups, as well as considering α=0.5 and power=80%. We assessed the methylation status of the BIRC5 gene in PBMCs of BD and control groups by methylation-specific polymerase chain reaction (MS-PCR). Plasma levels of survivin were measured by enzyme- linked immunosorbent assay.

Results

Oral aphthous ulcer, genital ulcer, and skin lesions were the most common clinical manifestations in BD group. MS-PCR showed that the deoxyribonucleic acid samples of BD and control groups were not different in methylated and unmethylated areas and alleles were heterozygote. No significant difference was observed in the plasma levels of survivin in BD (98.86±25.5 pg/mL) and control (118.16±37.4 pg/mL) groups. There was no significant correlation between survivin plasma levels and BD activity.

Conclusion

Our study did not show any evidence of association between the alteration in the BIRC5 gene methylation, survivin production, and apoptosis dysregulation in BD.

Evaluation of DNA methylation status of toll-like receptors 2 and 4 promoters in Behcet's disease

BACKGROUND

Altered innate immune function plays an important role in the initiation of inflammatory response in Behcet's disease (BD). Toll-like receptors (TLRs) are the master regulators of the innate immune system. Because the role of TLRs remains unknown in the pathogenesis of BD, the present study aimed to evaluate the expression levels and methylation status of the TLR2 and TLR4 promoters in patients with BD.

METHODS

In the present study, Iranian Azeri BD patients (n = 47) with an active (n = 22) and inactive (n = 25) period, and healthy controls (n = 61), were matched according to age, sex and ethnicity. TLR2 and TLR4 genes promoter CpG islands were predicted with the Eukaryotic Promoter Database (https://epd.vital-it.ch). Methylated DNA immunoprecipitation (MeDIP) was conducted.

RESULTS

The results showed that mRNA of TLR4 was significantly increased in the peripheral blood mononuclear cells (PBMCs) of BD patients with an active phase compared to the control group. Differences in mRNA of TLR4 between the inactive BD and control groups were not significant. Differences in TLR2 mRNA levels in the PBMCs of the active and inactive phase BD and control groups were not significant. The methylation rate of TLR4 gene promoter was significantly lower in the active and inactive BD groups compared to the control group. The difference between the active and inactive BD groups was not significant. There was no significant difference in the methylation rates of the TLR2 gene between studied groups.

CONCLUSIONS

Our preliminary findings suggest that the hypomethylation of TLR4 gene may be involved in the pathogenesis of BD via increasing TLR4 expression.

The expression and methylation status of vitamin D receptor gene in Behcet's disease

INTRODUCTION

Vitamin D has important roles as a natural immune modulator via regulating the expression of genes which have been implicated in the pathophysiology of autoimmune diseases. Vitamin D function and its deficiency have been linked to a wide range of metabolic disorders including disorders of calcium metabolism, malignant, cardiovascular, infectious, neuromuscular, and inflammatory diseases. Environmental factors, genetic factors, and epigenetic changes contribute to Behcet's disease (BD) development. The aim of our study was to analyze the expression level and methylation status of the vitamin D receptor (VDR) gene promoter in the peripheral blood mononuclear cells (PBMCs) of patients with BD.

METHODS

In a case-control study, 48 Iranian Azeri patients with BD and 60 age-, sex- and ethnically-matched healthy controls were included. Venous blood samples were collected and PBMCs were isolated by Ficoll protocol. The DNA and RNA were subsequently extracted. Promoter methylation levels were evaluated by MeDIP-quantitative polymerase chain reaction (qPCR). The expression of VDR was evaluated by real-time PCR.

RESULTS

The results of quantitative real-time PCR analysis showed that the level of VDR expression in patients with BD was significantly lower than the control group (P = .013). There was no significant difference in the level of DNA methylation in the BD and control groups (P > .05). As the results show, the expression level of VDR gene was significantly different between female and male in the patient group (P = .001). VDR gene expression was significantly higher in subjects with phlebitis. No correlation was observed between VDR gene expression rate and BD activity.

CONCLUSION

VDR gene expression decreased in patients with BD. However, there is no suggestion evidence that the expression level of VDR is regulated by a unique DNA methylation mechanism. No correlation exists between VDR gene expression and BD activity.

Association of Ulcerative Colitis with FOXP3 Gene Polymorphisms and Its Colonic Expression in Chinese Patients

Abnormalities of forkhead box P3 (FOXP3) are implicated in various autoimmune diseases. This study is aimed at investigating the association of ulcerative colitis (UC) with FOXP3 polymorphisms and its colonic expression in Chinese patients. Polymorphisms of rs3761548, rs2232365, rs2294021, and rs3761547 were examined in 472 UC patients and 525 healthy controls using the SNaPshot method. The colonic expression of FOXP3 mRNA and protein was assayed in inflammatory mucosa of 34 UC patients and normal mucosa of 36 patients with benign sigmoid polyps (normal controls) using real-time quantitative polymerase chain reaction and immunohistochemical analysis. All data were handled separately for females and males. As a result, the carrier frequencies with at least one variant allele of rs3761548, rs2232365, and rs229402 increased in female and male UC patients compared with healthy controls. Significant differences in these carrier frequencies were also observed between patients with mild and moderate UC and patients with severe UC. The expression of FOXP3 was higher in UC patients (both males and females), especially those with severe UC, than in normal controls. The expression of FOXP3 was downregulated in UC patients having at least one variant allele compared with UC patients having no variant allele of rs3761548, rs2232365, and rs2294021. Male gender (β = −0.341), rs2294021 variation (β = −0.503), and severe UC (β = 0.361) were independently related to the mRNA expression of FOXP3 in UC patients. Together, our findings indicated that FOXP3 (rs3761548, rs2232365, and rs2294021) variations increased the risk of UC and were associated with the lower colonic expression of FOXP3 in UC patients.

The FOXP3 rs3761547 Gene Polymorphism in Multiple Sclerosis as a Male-Specific Risk Factor

The FOXP3 gene encodes a transcription factor and is predominantly expressed in the CD4+CD25+ regulatory T cells which plays a pivotal role in the maintenance of immune homeostasis. The defect of FOXP3 gene may provide a critical link between autoimmunity and immune deficiency. The purpose of our study was to evaluate the association of chosen polymorphisms of FOXP3 gene (rs3761549, rs3761548, rs3761547) with different clinical multiple sclerosis (MS) data of our relapsing-remitting groups of patients and in control group. The study was performed on a group consisting of 174 relapsing-remitting MS patients, diagnosed under 40 years of life, and 174 healthy volunteers. Genotyping was performed using a real-time PCR-based method by TaqMan Assays. Significant differences in distribution of allele C rs3761547 were found in male MS patients in comparison to the male healthy group (p = 0.046, OR 1.95, CI 95%). No association between MS and the other two polymorphisms was observed in males and females of both studied groups. Our data may suggest that FOXP3 rs3761547 gene polymorphism are related notably with the increased risk of MS development in males patients. To our knowledge this is the first study which indicates gender-specific relation between rs3761547 FOXP3 gene polymorphism and multiple sclerosis.

FOXP3 rs3761548 polymorphism is associated with knee osteoarthritis in a Turkish population

AIM

Functional polymorphisms located in FOXP3 intron 1 was recently found to be associated with rheumatoid arthritis (RA). Although RA is an autoimmune disease, there is supporting evidence that activated maladaptive responses including pro-inflammatory pathways play roles in osteoarthritis (OA), similar to RA. The aim of this study was to explore the relationship between rs2232365 (-924A/G) and rs3761548 (-3279A/C) polymorphisms as well as possible changes in the 600 bp promoter region of FOXP3 and knee OA.

METHODS

Patients with primary knee OA (n = 300) and healthy individuals (n = 300) were examined for rs3761548 and rs2232365 FOXP3 gene polymorphisms by the polymerase chain reaction-restriction fragment-length polymorphism method. The 600 bp promoter region (between -500 and +100) of the gene was also sequenced with direct sequencing in 50 knee OA patients and 50 healthy individuals.

RESULTS

There were no sequence variants in the promoter region tested both in OA patients and healthy controls. The SNP rs2232365 showed no association with OA susceptibility and severity and the results of other genetic models were also nonsignificant. On the other hand, rs3761548 AC (P = 0.003), AA + CC (P = 0.0014) as well as AC + AA (P = 0.40) genotypes showed association with Grade 4 knee OA patients.

CONCLUSION

Our findings indicated that the association between FOXP3 rs2232365 polymorphism and knee OA tended to yield negative results but the FOXP3 rs3761548 C allele was associated with elevated risk of OA in Grade 4 knee OA patients in a Turkish population.

Methylation status of interleukin-6 gene promoter in patients with Behçet's disease

BACKGROUND

IL-6 mRNA expression is significantly high in many autoimmune diseases such as Behçet's disease; this is often related with more aggressive phenotypes. Nevertheless, the essential molecular process for its high expression has not been completely realized. The aim of this study was undertaken to estimate the gene copy number variation and promoter methylation to IL-6's high expression.

METHODS

This study was performed on 51 patients and 61 healthy controls. Initially, DNA and RNA were extracted from all specimens. Promoter methylation levels of IL-6 were evaluated by MeDIP-qPCR technique. Also, IL-6 gene expression was measured by Real-time PCR. After that, we evaluated the relationship between gene expression and methylation, as well as their relationship with clinical specification.

RESULTS

As we expected, the expression level of IL-6 gene increased significantly in the patient group compared to the healthy subjects. Also, the relative promoter methylation level of the IL-6 mRNA was significantly lower in patient group compared to healthy group (p<0.001).

DISCUSSION

We disclosed that the promoter hypomethylation may be considered as one of the main defects for IL-6 mRNA high expression in patients with Behçet's disease.

Hypermethylation of IL-10 gene is responsible for its low mRNA expression in Behçet's disease

Interleukin-10 (IL-10), produced generally by monocyte, T helper type 2 (Th2), and regulatory T cells (Treg), plays a central role in controlling inflammatory responses and regulating the immune response of the IL-10 mRNA expression. It is significantly down-regulated in many autoimmune diseases such as Behçet's disease; this is mostly associated with more aggressive complications. Nevertheless, the essential molecular process for its low expression has not been completely realized. The aim of this project was attempted to estimate the gene expression, promoter methylation, and protein levels to IL-10's down-regulated expression. In this study, blood samples from 51 (4 missed) patients and 63 (2 missed) healthy controls were taken, with the mononuclear cells isolated by the Ficoll Protocol. DNA and RNA were then subsequently extracted. Promoter methylation levels were evaluated by MeDIP-qPCR. Following this, the extracted RNA was converted to cDNA using the RT-PCR method, with the expression of IL-10 later evaluated by Real-time PCR. And then, serum levels of IL-10 were measured using ELISA method. As we expected, the expression level of the IL-10 gene was seen to significantly decline in the patient group in comparison to the control. Also, the rate of promoter methylation was significantly higher in the IL-10 mRNA low expression group (patient group) compared to its high expression group (healthy group) (P < 0.001). We revealed that hypermethylation of promoter region was the principal defect for the IL-10 mRNA low expression in patients with Behçet's disease.