Association ofIRF5gene polymorphisms with rheumatoid arthritis in a Tunisian population

Inflammatory diseases causing joint and bone destruction: rheumatoid arthritis and hemophilic arthropathy

Various diseases and conditions cause joint disorders. Osteoarthritis (OA) is characterized by the degeneration of articular cartilage, synovitis, and anabolic changes in surrounding bone tissues. In contrast, rheumatoid arthritis (RA) and hemophilic arthropathy (HA) display marked destruction of bone tissues caused by synovitis. RA is a representative autoimmune disease. The primary tissue of RA pathogenesis is the synovial membrane and involves various immune cells that produce catabolic cytokines and enzymes. Hemophilia is a genetic disorder caused by a deficiency in blood clotting factors. Recurrent intra-articular bleeding leads to chronic synovitis through excessive iron deposition and results in the destruction of affected joints. Although the triggers for these two joint diseases are completely different, many cytokines and enzymes are common in the pathogenesis of both RA and HA. This review focuses on the similarities between joint and bone destruction in RA and HA. The insights may be useful in developing better treatments for hemophilia patients with arthropathy and osteoporosis by leveraging advanced therapeutics for RA.

Molecular Dynamic Simulations Unravel the Underlying Impact of Missense Mutation in Autoimmunity Gene PTPN22 on Predisposition to Rheumatoid Arthritis

Genetic mutations in various proteins have been implicated with increased risk or severity of rheumatoid arthritis (RA) in different population groups. In the present case-control study, we have investigated the risk association of single nucleotide mutations present in some of the highly reported anti-inflammatory proteins and/or cytokines, with RA susceptibility in the Pakistani subjects. The study involves 310 ethnically and demographically similar participants from whom blood samples were taken and processed for DNA extraction. Through extensive data mining, 5 hotspot mutations reported in 4 genes, that is, interleukin (IL)-4 (-590; rs2243250), IL-10 (-592; rs1800872), IL-10 (-1082; rs1800896), PTPN22 (C1858T; rs2476601), and TNFAIP3 (T380G; rs2230926), were selected for RA susceptibility analyses using genotyping assays. The results demonstrated the association of only 2 DNA variants [rs2243250 (odds ratio, OR = 2.025, 95% confidence interval, CI = 1.357-3.002, P = 0.0005 Allelic) and rs2476601 (OR = 4.25, 95% CI = 1.569-11.55, P = 0.004 Allelic)] with RA susceptibility in the local population. The former single nucleotide mutation was nonfunctional, whereas the latter, residing in the exonic region of a linkage-proven autoimmunity gene PTPN22, was involved in R620→W620 substitution. Comparative molecular dynamic simulations and free-energy calculations revealed a radical impact on the geometry/confirmation of key functional moieties in the mutant protein leading to a rather weak binding of W620 variant with the interacting receptor (SRC kinase). The interaction imbalance and binding instabilities provide convincing clues about the insufficient inhibition of T cell activation and/or ineffective clearance of autoimmune clones-a hallmark of several autoimmune disorders. In conclusion, the present research describes the association of 2 hotspot mutations in IL-4 promoter and PTPN22 gene with RA susceptibility in the Pakistani study cohort. It also details how a functional mutation in PTPN22 impacts the overall protein geometry, charge, and/or receptor interactions to contribute to RA susceptibility.

Polymorphisms in IRF5 and TYK2 Genes Are Associated with Rheumatoid Arthritis in a Chinese Han Population

BACKGROUND The IRF5 and TYK2 gene polymorphisms are associated with autoimmune diseases. However, the relationship between the IRF5 and TYK2 gene polymorphisms and RA risk in the Chinese Han population was inconsistent. MATERIAL AND METHODS A total of 578 RA patients (case group) and 578 healthy controls (control group) were assessed in a case-control study. Genotyping of IRF5 (Exon 6 insertion/deletion (in/de), rs2004640, rs2070197, rs10954213) and TYK2 (rs280500, rs280519, rs280521, rs8108236, rs12720253) was performed by direct sequencing method. Data analysis was performed by SHEsis. RESULTS The rs2004640T allele (P=0.0003) and the dominant (P=0.001) and recessive (P=0.01) models of rs2004640 were associated with RA risk after stringent Bonferroni correction (0.05/4). The IRF5 exon 6 (in), rs2070197 and rs10954213 were not associated with RA (P>0.05). Two haplotypes of IRF5 (DTAT and DTGG) were associated with RA susceptibility (P<0.05). In addition, the frequencies of TYK2 rs280500A, rs280521A, and rs8108236A were significantly higher in the RA group compared with the control group (P<0.05). TYK2 rs280500, rs280521, and rs8108236 were associated with RA susceptibility in the dominant model, but the same was not observed for rs280519 and rs12720253 (P<0.05). Furthermore, 3 risk haplotypes (AAAGT, AGGAT, and GAAAT) and a protective haplotype (GAGGT) of TYK2 gene were associated with RA susceptibility (P<0.05). CONCLUSIONS Our results suggest that IRF5 rs2004640, TYK2 rs280500, rs280521, rs8108236, and haplotypes IRF5 (DTAT and DTGG) and TYK2 (AAAGT, AGGAT, GAAAT, and GAGGT) are susceptible factors for RA in a Chinese Han population.

Genetic implications in the pathogenesis of rheumatoid arthritis; an updated review

Three important factors, including genetics, environment factors and autoimmunity play a role in the pathogenesis of rheumatoid arthritis (RA). The heritability of RA has been accounted to be 50-60%, while the HLA involvement in heritability of the disease has been accounted to be 10-40%. It has been documented that shared epitope (SE) alleles, such as HLA-DRB1*01 and DRB1*04, some HLA alleles like HLA-DRB1*13 and DRB1*15 are connected to RA susceptibility. An advanced classification of SE categorizes SE alleles into four main groups namely, S1, S2, S3D, and S3P. The S2 and S3P groups have been linked to susceptibility of seropositive RA. Various genome-wide association studies (GWAS) have discovered many susceptibility loci implicated in pathogenesis of RA. Some of the important single nucleotide polymorphisms (SNPs) linked to RA are TRAF1, STAT4, CTLA4, IRF5, CCR6, PTPN22, IL23R, and PADI4. HLA and non-HLA genes may discriminate anti-cyclic citrullinated peptide (anti-CCP) antibody-positive and anti-CCP-negative RA groups. Furthermore, risk of the disease has also been linked to environmental agents, mainly cigarette smoking. Pharmacogenomics has also confirmed SNPs or genetic patterns that might be linked to drugs responses. Different aspects of genetic involvement in the pathogenesis, etiology, and RA complications are reviewed in this article.

Interferon regulatory factor 5 gene polymorphism in Egyptian children with systemic lupus erythematosus

Background

Increased expression of interferon-inducible genes is implicated in the pathogenesis of systemic lupus erythematosus (SLE). Interferon regulatory factor 5 (IRF5) is one of the transcription factors regulating interferon and was proved to be implicated in the pathogenesis of SLE in different populations.

Objectives

The objective of this study was to investigate the correlation between polymorphisms of the IRF5 gene and SLE susceptibility in a cohort of Egyptian children and to investigate their association with clinico-pathological features, especially lupus nephritis.

Subjects and methods

Typing of interferon regulatory factor 5 rs10954213, rs2004640 and rs2280714 polymorphisms were done using polymerase chain reaction-restriction fragment length polymorphism for 100 children with SLE and 100 matched healthy controls.

Results

Children with SLE had more frequent T allele and TT genotype of rs2004640 ( Pc = 0.003 and 0.024, respectively) compared to controls. Patients with nephritis had more frequent T allele of rs2004640 compared to controls ( Pc = 0.003). However the allele and genotype frequencies of the three studied polymorphisms did not show any difference in patients with nephritis in comparison to those without nephritis. Haplotype GTA of rs10954213, rs2004640 and rs2280714, respectively, was more frequent in lupus patients in comparison to controls ( p = 0.01) while the haplotype GGG was more frequent in controls than lupus patients ( p = 0.011).

Conclusion

The rs2004640 T allele and TT genotype and GTA haplotype of rs rs10954213, rs2004640, and rs2280714, respectively, can be considered as risk factors for the development of SLE. The presence of the rs2004640 T allele increases the risk of nephritis development in Egyptian children with SLE.

Interferon regulatory factor 5 in human autoimmunity and murine models of autoimmune disease

Interferon regulatory factor 5 (IRF5) has been demonstrated as a key transcription factor of the immune system, playing important roles in modulating inflammatory immune responses in numerous cell types including dendritic cells, macrophages, and B cells. As well as driving the expression of type I interferon in antiviral responses, IRF5 is also crucial for driving macrophages toward a proinflammatory phenotype by regulating cytokine and chemokine expression and modulating B-cell maturity and antibody production. This review highlights the functional importance of IRF5 in a disease setting, by discussing polymorphic mutations at the human Irf5 locus that lead to susceptibility to systemic lupus erythematosus, rheumatoid arthritis, and inflammatory bowel disease. In concordance with this, we also discuss lessons in IRF5 functionality learned from murine in vivo models of autoimmune disease and inflammation and hypothesize that modulation of IRF5 activity and expression could provide potential therapeutic benefits in the clinic.

Are polymorphisms of the immunoregulatory factor CD40LG implicated in acute transfusion reactions?

The CD40 ligand (CD40L/CD154), a member of TNF superfamily, is notably expressed on activated CD4+ T-cells and stimulated platelets. CD40L is linked to a variety of pathologies and to acute transfusion reactions (ATR). Mutations in this gene (CD40LG) lead to X-linked hyper-IgM syndrome. Some CD40LG polymorphisms are associated with variable protein expression. The rationale behind this study is that CD40L protein has been observed to be involved in ATR. We wondered whether genetic polymorphisms are implicated. We investigated genetic diversity in the CD40LG using DHPLC and capillary electrophoresis for screening and genotyping (n = 485 French and Tunisian blood donors). We identified significant difference in the CD40LG linkage pattern between the two populations. Variant minor alleles were significantly over-represented in Tunisian donors (P<0.0001 to 0.0270). We found higher heterogeneity in the Tunisian, including three novel low frequency variants. As there was not a particular pattern of CD40LG in single apheresis donors whose platelet components induced an ATR, we discuss how this information may be useful for future disease association studies on CD40LG.

IRF5rs2004640 single nucleotide polymorphism is associated with susceptibility to rheumatoid arthritis in South Indian Tamils

Polymorphism of interferon regulatory factor 5 (IRF5), a latent transcription factor gene has been associated with various auto-immune diseases. Our aim was to study the IRF5rs2004640 gene polymorphism and its association with disease susceptibility, disease phenotype and treatment response in South Indian Tamil patients with rheumatoid arthritis (RA).The study was conducted on 217 RA patients fulfilling the American College of Rheumatology (ACR) 2010 criteria and 482 healthy controls (HCs) without family history of autoimmune disease. The IRF5rs2004640 genotyping was performed using a TaqMan 5' allelic discrimination assay. We found that the IRF5rs2004640T allele [P < 0.0001, odds ratio (OR) 3.25, 95% confidence interval (CI) 2.55-4.12] and TT genotype (P < 0.0001, OR 4.60, 95% CI 3.23-6.57) were significantly more frequent in RA patients as compared with HCs. No association was found between IRF5rs2004640 polymorphism, clinical manifestations, autoantibody profile and treatment response. IRF5rs2004640 T (mutant) allele may be a susceptibility factor conferring risk for RA in South Indian Tamils, whereas G allele (wild type) may be protective.

Association of the IRF5 rs2004640 polymorphism with rheumatoid arthritis: a meta-analysis

Several molecular epidemiological studies have been conducted in recent years to evaluate a possible association between the interferon regulatory factor 5 (IRF5) rs2004640 polymorphism and rheumatoid arthritis risk in diverse populations. However, the results remain conflicting rather than conclusive. Our aim was to assess associations of IRF5 gene polymorphisms with rheumatoid arthritis risk. Meta-analysis was performed on six published case-control studies (from eight countries) that included 4,818 cases of rheumatoid arthritis and 4,316 controls. The rs2004640-T allele was associated with a significantly increased risk of rheumatoid arthritis when the dominant genetic model was applied (T/T + T/G versus G/G: P = 0.003, OR = 1.14, 95% CI 1.05-1.25). Upon stratified analysis by ethnicity, the rs2004640 polymorphism was associated with an increased rheumatoid arthritis risk in Caucasians when the homozygotic contrast model was employed(T/T versus G/G: P = 0.03, OR = 1.25, 95% CI 1.02-1.53) and this was also the case when the dominant genetic model was used (T/T + T/G versus G/G: P = 0.04, OR = 1.20, 95% CI 1.01-1.42), whereas, in Asian populations, only the dominant genetic model was associated with an increased rheumatoid arthritis risk (T/T + T/G versus G/G: P = 0.02, OR = 1.14, 95% CI 1.02-1.26). The results suggest that the IRF5 rs2004640 polymorphism is associated with rheumatoid arthritis especially when the dominant genetic model is applied.

Investigation of Caucasian rheumatoid arthritis susceptibility loci in African patients with the same disease

INTRODUCTION

The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus ('shared epitope', SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans.

METHODS

RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data were also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts.

RESULTS

After genotyping quality control procedures were performed, data on 28 Caucasian non-HLA susceptibility SNPs were available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p = 1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR = 0.71, 95% CI 0.29 - 1.74, p = 0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001.

CONCLUSIONS

The MAFs of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans, and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.

Associations between interferon regulatory factor 5 polymorphisms and rheumatoid arthritis: a meta-analysis

The aim of this study was to determine whether interferon regulatory factor 5 (IRF5) polymorphisms confers susceptibility to rheumatoid arthritis (RA) in populations with different ethnicities. We searched the literature using the Pubmed and Embase databases and conducted meta-analyses on associations between the four IRF5 polymorphisms (rs2004640, rs729302, rs752637, and rs2280714) and RA susceptibility, using fixed and random effects models. A total of 12 comparison studies were considered in this meta-analysis, which in total involved 7,916 RA patients and 6,452 controls, and eight European, three Asian, and one Argentinean population. Meta-analysis showed an association between the minor allele of rs2004640 and RA in all subjects (odds ratio [OR] = 0.928, 95 % confidence interval [CI] = 0.865-0.996, P = 0.037). After stratification by ethnicity, analysis indicated that the minor allele was significantly associated with RA in Europeans (OR = 0.889, 95 % CI = 0.839-0.941, P = 5.03 × 10(-6)), but not in Asians (OR = 1.057, 95 % CI = 0.978-1.144, P = 0.164). A direct comparison between anti-citrullinated peptide antibody-positive and -negative patients revealed no difference of the frequency of the rs2004640 minor allele (OR = 1.047, 95 % CI = 0.813-1.348, P = 0.724). Meta-analysis identified a significant association between RA and the minor allele of the rs729302 polymorphism in the overall population (OR = 0.896, 95 % CI = 0.826-0.972, P = 0.009) and in Asians (OR = 0.862, 95 % CI = 0.795-0.935, P = 3.50 × 10(-5)), but not in Europeans (OR = 0.951, 95 % CI = 0.877-1.031, P = 0.225). Meta-analysis showed an association between the minor allele of rs752637 and RA in Europeans (OR = 0.858, 95 % CI = 0.789-0.932, P = 3.03 × 10(-5)), but not in Asians (OR = 1.035, 95 % CI = 0.918-1.168, P = 0.572). No association was found between the rs2280714 polymorphism and RA susceptibility. This meta-analysis confirms that the IRF5 rs2004640, rs729302 and rs752637 polymorphisms are associated with RA susceptibility in different ethnic groups, especially in Europeans and Asians, but further study of this association is required in other ethnic groups.

Genetic risk factors in lupus nephritis and IgA nephropathy--no support of an overlap

Background

IgA nephropathy (IgAN) and nephritis in Systemic Lupus Erythematosus (SLE) are two common forms of glomerulonephritis in which genetic findings are of importance for disease development. We have recently reported an association of IgAN with variants of TGFB1. In several autoimmune diseases, particularly in SLE, IRF5, STAT4 genes and TRAF1-C5 locus have been shown to be important candidate genes. The aim of this study was to compare genetic variants from the TGFB1, IRF5, STAT4 genes and TRAF1-C5 locus with susceptibility to IgAN and lupus nephritis in two Swedish cohorts.

Patients and Methods

We genotyped 13 single nucleotide polymorphisms (SNPs) in four genetic loci in 1252 DNA samples from patients with biopsy proven IgAN or with SLE (with and without nephritis) and healthy age- and sex-matched controls from the same population in Sweden.

Results

Genotype and allelic frequencies for SNPs from selected genes did not differ significantly between lupus nephritis patients and SLE patients without nephritis. In addition, haplotype analysis for seven selected SNPs did not reveal a difference for the SLE patient groups with and without nephritis. Moreover, none of these SPNs showed a significant difference between IgAN patients and healthy controls. IRF5 and STAT4 variants remained significantly different between SLE cases and healthy controls. In addition, the data did not show an association of TRAF1-C5 polymorphism with susceptibility to SLE in this Swedish population.

Conclusion

Our data do not support an overlap in genetic susceptibility between patients with IgAN or SLE and reveal no specific importance of SLE associated SNPs for the presence of lupus nephritis.

Association of polymorphisms in estrogen and thyroid hormone receptors with thyroid cancer risk

The receptors for thyroid hormone (THR) and oestrogen (ESR) are prototypes of nuclear transcription factors that regulate the expression of target genes. Genetic alterations in the genes of these receptors were found to be involved in cancer development. In this study we investigated the association of one SNP (rs2228480, T594T) and one microsatellite marker (D6S440) within the ESR1 gene and a dinucleotide repeat (D17S2189) within the THRA gene, with thyroid cancer risk. A case-control association study was conducted with 299 healthy individuals and 106 patients with thyroid cancer. Genotypic and allelic frequencies for the dinucleotide repeat in the ESR1 gene were similar between thyroid cancer patients and controls. For the AC repeat in the THRA gene, a slightly significant difference was found for the genotype 18/20 between the two groups (P = 0.034), which suggests that alleles with less than 20 repeats might have a protective effect in thyroid cancer risk. For the SNP T594T, the A allele was much more prevalent in patients than in controls and was highly associated with the risk of thyroid cancer (OR: 4,56; IC: 3.23-6.44; P < 10(-18)) and seems to have an additive mode of action. In conclusion, our data suggest that the SNP T594T but not the D6S440 and D17S189 is associated with thyroid cancer risk.