Study of Programmed Cell Death 1 (PDCD1) Gene Polymorphims in Iranian Patients with Ankylosing Spondylitis

Copy number variation of IL17RA gene and its association with the ankylosing spondylitis risk in Iranian patients: a case-control study

Background

Ankylosing spondylitis (AS) is considered as a subtype of spondyloarthritis (SpA) that mainly leads to fatigue, stiffness, spinal ankylosis, and impaired physical functions with reduced quality of life. Interleukin (IL)-17A provokes additional inflammatory mediators and recruits immune cells to the inflamed site. IL17 expression increased in various inflammatory disorders including psoriasis, rheumatoid arthritis, multiple sclerosis, crohn’s disease, and ankylosing spondylitis. The current study aimed to evaluate the association of IL17RA copy number changes with the susceptibility to AS and their correlation to IL17RA expression in Iranian population.

Methods

IL17RA copy number genotyping assessments were carried out in 455 AS patients and 450 healthy controls, using custom TaqMan CNV assays. TaqMan primers and probe were located in Chr.22:17109553 based on pre-designed IL17RA Copy Number Assay ID, Hs02339506_cn. mRNA expression of IL17RA was also measured by SYBR Green real-time polymerase chain reaction (PCR).

Results

A IL17RA copy number loss (< 2) was associated with AS compared to 2 copies as reference (OR:2.18, 95% CI: (1.38–3.44), P-value < 0.001) and increased the risk of AS. IL17RA mRNA expression showed a significant increase in peripheral blood mononuclear cells (PBMCs) of all AS individuals than controls. The mRNA expression level of 2 copies was significantly higher in AS patients.

Conclusions

Our findings revealed that a low copy number of IL17RA might confer a susceptibility risk to AS. However, it is probably not directly involved in the regulation of IL17RA mRNA expression. Epigenetic mechanisms like DNA methylation, post-transcriptional, and -translational modifications that regulate the expression of the genes may contribute in upregulation of IL17RA mRNA expression in the loss of gene copy number condition.

Effect of food intake and ambient air pollution exposure on ankylosing spondylitis disease activity

BACKGROUND

Ankylosing spondylitis (AS) is a chronic inflammatory disease characterized by axial arthritis. The genetic-environmental factors seem to be involved in the pathogenesis of the disease and the disease debilitates patients during the most productive stages of their lives. The aim of this study was to examine the relationships between two environmental factors, diet and air pollution with disease activity and functional impairment in AS.

METHODS

A case-control study was carried out. Thirty patients with AS and 30 age and sex-matched healthy controls were included. Disease scores including BASMI, BASDAI, BASFI, and BASG were calculated by means of the international Ankylosing Spondylitis Assessment working group consensus recommendations. The food intake was evaluated by semi-quantitative food frequency questionnaire (147 items FFQ). Level of air pollution indices, PM10 and PM2.5 information was obtained from the Tehran air quality control network.

RESULTS

Total energy and fat intake, some vitamins (A, B1, B2, C) and mineral intake (potassium, calcium, iron, phosphorus, magnesium, zinc, copper and selenium) were significantly higher in patients with AS compared to controls. Fat component consumption especially Saturated Fat of Food was moderately correlated with BASFI score. PM2.5 long term exposure was strongly correlated with BASMI, BASFI and BASDAI scores of patients.

CONCLUSION

High-fat diet and long term exposure to air pollution are associated with worse disease outcomes reported in patients with AS. This is an interesting area of investigation in AS pathogenesis and management.

Association study between killer immunoglobulin-like receptor polymorphisms and ankylosing spondylitis disease: An updated meta-analysis

BACKGROUND

Several genetic studies have assessed the association between polymorphisms in killer immunoglobulin-like receptors (KIR) genes and susceptibility of individuals to ankylosing spondylitis (AS), but the findings have been inconclusive and incongruous. Therefore, we conducted this meta-analysis of all case-control studies meeting the inclusion criteria for obtaining an exact conclusion of the effect of KIR polymorphisms on the risk of AS.

METHODS

A systematic literature search was conducted in electronic databases, including Scopus web of science, ScienceDirect, and PubMed to find all eligible studies exploring the association between KIR polymorphisms and the risk of AS, prior to June 2017. Pooled odds ratios (OR) and their corresponding 95% CIs were used to evaluate the strength of the association between KIR polymorphisms and the risk of AS.

RESULTS

A total of 16 case-control studies, encompassed in 12 papers, with 1770 cases and 2907 healthy subjects were included in the meta-analysis. This meta-analysis revealed three significant positive associations of 2DS1, 2DS5, and 3DS1 with susceptibility to AS, while two significant negative associations of 2DL2 and 2DS2 with susceptibility to AS were identified. In the subgroup analysis based on human leukocyte antigen (HLA)-B*27 positive patients and healthy subjects, results indicated that there were four significant positive associations between 2DL5, 2DS4, 2DS5, 3DS1 polymorphisms and susceptibility to AS in HLA-B*27-positive patients; a significant negative association of 3DL1 in HLA-B*27-positive patients was found.

CONCLUSIONS

While 2DS1, 2DS5, and 3DS1 polymorphisms increased AS risk, 2DL2 and 2DS2 polymorphisms were associated with reduced AS susceptibility.

PD-1 Haplotype Combinations and Susceptibility of Patients to Squamous Cell Carcinomas of Head and Neck

INTRODUCTION

Head and neck squamous cell carcinomas (HNSCCs) are the most common cancers of head and neck and the sixth most common malignancy worldwide. Programmed cell death 1 (PD-1) is an immune inhibitory molecule which through interaction with its ligands recruits protein phosphatase resulting in immune response inhibition. Expression of PD-1 ligands on tumor cells is considered as one of the crucial immune evasion mechanisms. This study aimed to investigate the association of PD-1 gene polymorphisms at positions PD1.3 (rs11568821), PD1.5 (rs2227981) and PD1.9 (rs2227982) with susceptibility to HNSCCs.

SUBJECTS AND METHODS

150 patients pathologically confirmed to suffer from HNSCCs and 150 age-sex matched healthy controls were recruited in this study. Genomic DNA was extracted from white blood cells of all participants. Restricted fragment length polymorphisms (RFLP)-PCR was performed using site specific primers to determine the genotypes in each position.

RESULTS

Statistical analyses indicated no significant differences in the frequencies of genotypes, alleles as well as haplotypes between patients and controls (P > 0.05), however, haplotype combination differed significantly between two groups. GCC/GCT, GCC/GCC and GCT/GCC were higher in the HNSCC patients than the control group (P < 0.05). On the other hand, in the controls, GCT/GCT, GCT/ACC, GCT/ACT and ACC/GCT were more frequent. No significant association was found with various HNSCC clinicopathological characteristics.

DISCUSSION

Our results suggested that although PD-1 gene polymorphisms at three investigated positions are not solely associated with susceptibility to HNSCCs, haplotype combinations emerged from these three loci may render susceptibility.

PD-1/PD-L and autoimmunity: A growing relationship

Programmed death 1 (PD-1) and its ligands, namely PD-L1 and PD-L2, are one of the key factors responsible for inhibitory T cell signaling, mediating the mechanisms of tolerance and providing immune homeostasis. Mounting evidence demonstrates that impaired PD-1:PD-L function plays an important role in a variety of autoimmune diseases such as Type 1 diabetes (T1D), encephalomyelitis, inflammatory bowel diseases (IBD), Rheumatoid Arthritis (RA), autoimmune hepatitis (AIH), Behcet's disease (BD), myasthenia gravis (MG), autoimmune uveitis (AU), Sjögren's syndrome (SjS), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), myocarditis, and ankylosing spondylitis (AS). By investigating the candidate genes, genome-wide association studies, and identification of single nucleotide polymorphisms (SNPs) in PD-1 gene in humans, it has been shown that there is a higher risk in relevant genetic associations with developing autoimmune diseases in certain ethnic groups. In this review we have tried to present a comprehensive role of PD-1:PD-L in all recently studied autoimmune diseases.

New insights toward the pathogenesis of ankylosing spondylitis; genetic variations and epigenetic modifications

Ankylosing spondylitis (AS) is a chronic inflammatory autoimmune disease, characterized by typically an axial arthritis. AS is the prototype of a group of disorders called spondyloarthropathies, which is believed to have common clinical manifestations and genetic predisposition. To date, the exact etiology of AS remains unclear. Over the past few years, however, the role of genetic susceptibility and epigenetic modifications caused through environmental factors have been extensively surveyed with respect to the pathogenesis of AS, resulted in important advances. This review article focuses on the recent advances in the field of AS research, including HLA and non-HLA susceptibility genes identified in genome-wide association studies (GWAS), and aberrant epigenetic modifications of gene loci associated with AS. HLA genes most significantly linked with AS susceptibility include HLA-B27 and its subtypes. Numerous non-HLA genes such as those in ubiquitination, aminopeptidases and MHC class I presentation molecules like ERAP-1 were also reported. Moreover, epigenetic modifications occurred in AS has been summarized. Taken together, the findings presented in this review attempt to explain the circumstance by which both genetic variations and epigenetic modifications are involved in triggering and development of AS. Nonetheless, several unanswered dark sides continue to clog our exhaustive understanding of AS. Future researches in the field of epigenetics should be carried out to extend our vision of AS etiopathogenesis.

PDCD1 PD-1.3 polymorphism and allergic bronchial asthma in Russian and Buryat patients

OBJECTIVE

The programmed death-1 receptor, PD-1, is a negative regulator of T-cell activation. The PD-1.3 polymorphism of the PD-1 gene (PDCD1) has been previously shown to be associated with several autoimmune and inflammatory disorders including systemic lupus erythematosus and multiple sclerosis. We examined for the first time PD-1.3 association with another inflammatory disease with strong immune component, IgE-mediated bronchial asthma, its severity and its biochemical markers (total serum IgE and IL-4).

METHODS

PD-1.3 G/A was genotyped by PCR-RFLP analysis using two different populations: Caucasian (492 Russian individuals) and Asian (276 Buryat individuals).

RESULTS

We found a significant association of the PD-1.3 polymorphism with IgE-mediated bronchial asthma and total serum IgE level in the Russian population. Combined genotype AA+AG was correlated with risk of developing allergic bronchial asthma (OR = 1.78, 95% CI 1.13-2.78, p = 0.011) and lower concentrations of total serum IgE (p = 0.001) compared with the wild-type genotype GG. However, PD-1.3 was not polymorphic in the Buryat population.

CONCLUSIONS

PD-1.3 polymorphism of the PD-1 gene (PDCD1) may contribute to the development of allergic asthma in the Russians but not in the Buryats. Our results could be helpful for a better understanding of the effect of this polymorphism on the development of diseases with strong immune components.

Meta-analysis of genetic polymorphisms in programmed cell death 1. Associations with rheumatoid arthritis, ankylosing spondylitis, and type 1 diabetes susceptibility

OBJECTIVE

The aim of this study was to determine whether genetic polymorphisms in programmed cell death 1 (PDCD1 or PD1) are associated with susceptibility to rheumatoid arthritis (RA), ankylosing spondylitis (AS), and type 1 diabetes (T1D).

METHODS

We conducted a meta-analysis to investigate the association between PDCD1 polymorphisms and RA, AS, and T1D in the overall population and in specific ethnic populations.

RESULTS

Sixteen studies, comprising 13,210 patients and 17,073 controls, were conducted for the meta-analysis including 4 studies on RA, 4 on AS, and 8 on T1D. The meta-analysis showed an association between RA and the 2 alleles of the PD1.3 polymorphism in the overall population [odds ratio (OR) 1.183, 95 % confidence interval (95 % CI) 1.005-1.392, p = 0.043]. However, meta-analysis showed no association between RA and the 2 alleles of the PD1.1 and PD1.5 polymorphisms in the overall population. Meta-analysis identified an association between AS and the 2 alleles of the PD1.5 and PD1.9 polymorphisms in the Asian population (OR 1.251, 95 % CI 1.019-1.535, p = 0.033; OR 1.975, 95 % CI 1.286-3.034, p = 0.002, respectively). The meta-analysis revealed a significant association between T1D and the 2 alleles of the PD1.3 polymorphism in the European population (OR 1.098, 95 % CI 1.029-1.171, p = 0.005). The meta-analysis showed an association between the PD1.5 polymorphism and T1D in Asians (OR 1.332, 95 % CI 1.067-1.663, p = 0.011) and between the PD1.9 polymorphism and T1D in the Asian population (OR 1.363, 95 % CI 1.107-1.679, p = 0.004).

CONCLUSION

The meta-analysis suggests an association between the PD1.3 polymorphism and RA in the overall population and an association between the PD1.5 and PD1.9 polymorphisms, and AS in the Asian population. Furthermore, the PD1.3 , 5, and 9 polymorphisms were associated with T1D susceptibility in Europeans, or Asians.

The associations between PD-1, CTLA-4 gene polymorphisms and susceptibility to ankylosing spondylitis: a meta-analysis and systemic review

Previous surveys had evaluated the effects of the PD-1, CTLA-4 gene polymorphisms on susceptibility to ankylosing spondylitis (AS), but the results remained controversial. To briefly examine these consequences, a comprehensive meta-analysis was conducted to estimate the relationships between PD-1 rs11568821, rs2227982, rs2227981, CTLA-4 +49 A/G and -318 C/T polymorphisms and AS risk. The available articles dated to December 2014 were searched in the PUBMED, MEDLINE and EMBASE databases. The data of the genotypes and/or alleles for the PD-1 rs11568821, rs2227982, rs2227981, CTLA-4 +49 A/G and -318 C/T polymorphisms in the AS and control subjects were extracted, and statistical analysis was conducted by STATA 11.2 software. Summary odds ratios (ORs) with their 95 % confidence intervals (95 % CIs) were calculated to determine the strength of associations with fixed-effects or random-effects models. A total of eight published studies were finally involved in this meta-analysis. Meta-analysis of PD-1 rs2227982 polymorphism under the T allele versus C allele (OR 1.744, 95 % CI 1.477-2.059, P < 0.0001), TT+TC versus CC (OR 2.292, 95 % CI 1.654-3.175, P < 0.0001), TT versus CC (OR 1.883, 95 % CI 1.299-2.729, P = 0.001) revealed a significant association with AS. Our meta-analysis demonstrated that the rs2227982 polymorphism in the PD-1 gene might contribute to AS susceptibility. However, further studies with large sample sizes and among different ethnicity populations should be required to confirm this association.

Association of PDCD1 polymorphism to systemic lupus erythematosus and rheumatoid arthritis susceptibility

OBJECTIVE

This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05.

RESULTS

The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data.

CONCLUSION

There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

Association of PDCD1 polymorphism to Systemic Lupus Erythematosus and Rheumatoid Arthritis susceptibility

OBJECTIVE

This study aims to analyze the relationship of programmed cell death 1 (PDCD1) gene polymorphism (PD1.3G/A - rs11568821) with features of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) in a Southern Brazilian population.

METHODS

Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) was performed in 95 SLE and 87 RA patients and 128 control group individuals from Santa Catarina, Southern Brazil. The Hardy-Weinberg Equilibrium (HWE) test, and odds ratio (OR) were analyzed, considering CI 95% and p≤0.05.

RESULTS

The PD1.3A allele frequencies were 0.095 (SLE), 0.115 (RA) and 0.078 (controls). The genotypes of the control group were in HWE, while those of SLE and RA patients were not. However, we found no association between PD1.3 polymorphism and the SLE or RA susceptibility, nor clinical or epidemiological data.

CONCLUSION

There was no significant association between PD1.3 polymorphism and SLE or RA susceptibility in this Southern Brazilian population.

The programmed cell death 1 gene polymorphisms (PD 1.3 G/A, PD 1.5 C/T and PD 1.9 C/T) and susceptibility to ankylosing spondylitis: a meta-analysis

OBJECTIVE

The objective is to integrate all the eligible studies and investigate whether the programmed cell death 1 (PDCD-1) gene polymorphisms (PD 1.3 G/A, PD 1.5 C/T, and PD 1.9 C/T polymorphism) are correlated with ankylosing spondylitis risk (AS). Ankylosing spondylitis is a chronic inflammatory disease, and several genetic and environmental factors play an important role in the development and progression of AS. Significant associations between PDCD-1 gene polymorphisms (PD 1.3 G/A, PD 1.5 C/T or PD 1.9 C/T) and AS risk have been reported; however, some of these results are controversial.

METHODS

A systematic online search was performed using PubMed, EMBASE, Web of Science, and the Cochrane Library to identify case-control studies investigating the relationship between PD 1.3 G/A, PD 1.5 C/T, and PD 1.9 C/T polymorphisms and the susceptibility of AS. The pooled odds ratio (OR) with 95 % confidence interval (CI; 95 %) was calculated to assess the associations, and subgroup meta-analyses were performed according to the ethnicity of the study populations.

RESULTS

Five studies involving 909 cases and 982 controls met the inclusion criteria after assessment by two reviewers. Overall, there were no significant associations between PD 1.3 G/A and PD 1.5 C/T polymorphisms and AS risk. With regard to PD 1.9 C/T polymorphism, a significant association was found under the allele contrast model (T vs. C: OR 1.74, 95 % CI 1.48-2.06, P < 0.001), heterozygote model (CT vs. CC: OR 2.43, 95 % CI 1.65-3.59, P < 0.001), homozygote model (TT vs. CC: OR 1.87, 95 % CI 1.30-2.71, P = 0.001), and dominant model (CT/TT vs. CC: OR 2.29, 95 % CI 1.65-3.18, P < 0.001). In the subgroup analysis of ethnicity, no significant associations were found between PD 1.3 G/A, PD 1.5 C/T polymorphisms, and AS risk in either Asian or Caucasian populations. However, our study suggested that PD 1.9 C/T polymorphism was significantly associated with AS in Asian populations (T vs. C: OR 1.72, 95 % CI 1.46-2.04, P < 0.001; CT vs. CC: OR 2.44, 95 % CI 1.56-3.82, P < 0.001; TT vs. CC: OR 1.88, 95 % CI 1.30-2.73, P = 0.001; and CT/TT vs. CC: OR 2.29, 95 % CI 1.58-3.32, P < 0.001) but not in Caucasian populations.

CONCLUSION

The PD 1.9 C/T polymorphism may be involved in susceptibility to AS, particular in Asian populations; however, no significant associations were found between PD 1.3 G/A, PD 1.5 C/T polymorphisms, and AS risk in either Asians or Caucasians.

Recent insights into the role of the PD-1/PD-L1 pathway in immunological tolerance and autoimmunity

Autoimmune diseases represent a heterogeneous group of conditions whose incidence is increasing worldwide. This has stimulated studies on their etiopathogenesis, derived from a complex interaction between genetic and environmental factors, in order to improve prevention and treatment of these disorders. The relevance of T regulatory cells and of the PD-1/PD-L1 pathway in controlling immune responses has been highlighted. Recent studies have in particular elucidated the putative role of the PD-1/PD-L1 pathway in regulating T cell responses and its effects on immunological tolerance and immune-mediated tissue damage. The role of the PD-1/PD-L1 pathway in autoimmunity has been already investigated in vivo in several experimental animal models including insulin-dependent diabetes mellitus, systemic lupus erythematosus, myocarditis, encephalomyelitis, rheumatoid arthritis and inflammatory bowel diseases. With the advent of candidate gene and genome-wide association studies, single nucleotide polymorphisms (SNPs) in PD-1 gene in humans have demonstrated relevant associations with a higher risk of developing autoimmune diseases in certain ethnic groups. In this review we present recent insights into the role of the PD-1/PD-L1 pathway in regulating lymphocyte activation, promotion of T regulatory cell development and function, breakdown of tolerance and development of autoimmunity. We finally speculate on the possible development of novel therapeutic treatments in human autoimmunity by modulating the PD-1/PD-L1 pathway.

Ankylosing spondylitis: from cells to genes

Ankylosing spondylitis (AS) is a chronic inflammatory disease of unknown etiology, though it is considered an autoimmune disease. HLA-B27 is the risk factor most often associated with AS, and although the mechanism of involvement is unclear, the subtypes and other features of the relationship between HLA-B27 and AS have been studied for years. Additionally, the key role of IL-17 and Th17 cells in autoimmunity and inflammation suggests that the latter and the cytokines involved in their generation could play a role in the pathogenesis of this disease. Recent studies have described the sources of IL-17 and IL-23, as well as the characterization of Th17 cells in autoimmune diseases. Other cells, such as NK and regulatory T cells, have been implicated in autoimmunity and have been evaluated to ascertain their possible role in AS. Moreover, several polymorphisms, mutations and deletions in the regulatory proteins, protein-coding regions, and promoter regions of different genes involved in immune responses have been discovered and evaluated for possible genetic linkages to AS. In this review, we analyze the features of HLA-B27 and the suggested mechanisms of its involvement in AS while also focusing on the characterization of the immune response and the identification of genes associated with AS.

An exon polymorphism of programmed cell death 1 gene is associated with both the susceptibility and thoracolumbar kyphosis severity of ankylosing spondylitis in a Chinese Han population

BACKGROUND

Although human leukocyte antigen (HLA)-B27 gene is the major susceptible gene associated with ankylosing spondylitis (AS), it has been recognized that non-HLA-B27 genes also play key roles in the development of AS. The purpose of this study is to investigate whether a single nucleotide polymorphism (SNP) in the exon region of the programmed cell death 1 (PDCD-1) gene is associated with the susceptibility or the thoracolumbar kyphosis severity of AS in a Chinese Han population.

METHODS

A total of 255 AS patients between January 2008 and October 2012 were recruited in this study. Two hundred and three healthy patients were recruited as normal controls. According to the severity of thoracolumbar kyphosis, the AS patients were further divided into group A (patients with kyphosis <70°, n = 135) and group B (patients with kyphosis ≥70°, n = 120). One exon polymorphism, rs2227982 (C/T) of PDCD-1 gene, was selected for analysis. Genotyping was performed by TaqMan probe assays in all the subjects.

RESULTS

There were significant differences of genotype distributions of rs2227982 between AS patients and normal controls. The frequency of the T allele was significantly higher in AS patients when compared with normal controls. The frequency of the T allele in group B was significantly higher than that in group A. Carriage of the TT genotype increased the risk of severe thoracolumbar kyphosis 1.9-fold in AS patients.

CONCLUSIONS

Our study confirms a significant association between the SNP rs2227982 of PDCD-1 gene and the susceptibility of AS in a Chinese Han population. Moreover, the TT genotype is suggested to be associated with the severity of thoracolumbar kyphosis secondary to AS.