Interleukin-18, interleukin-12B and interferon-γ gene polymorphisms in Brazilian patients with rheumatoid arthritis: a pilot study

A novel missense compound heterozygous variant in TLR1 gene is associated with susceptibility to rheumatoid arthritis - structural perspective and functional annotations

INTRODUCTION

Besides human leukocyte antigen (HLA-DRB1) locus, more than 100 loci across the genome have been identified and linked with the onset, expression and/or progression of rheumatoid arthritis (RA). However, there are still grey areas in our understanding of the key genetic contributors of the disease, particularly in familial cases.

METHODS

In the present study, we have performed the whole exome sequencing (WES) of RA patients from two consanguineous families of Pakistan in a quest to identify novel, high-impact, RA-susceptibility genetic variants.

RESULTS

Through stepwise filtering, around 17,000 variants (common in the affected members) were recognized, out of which 2651 were predicted to be deleterious. Of these, 196 had direct relevance to RA. When selected for homozygous recessive mode of inheritance, two novel pathogenic variants (c.1324T>C, p.Cys442→Arg442; c.2036T>C, p.Ile679→Thr679) in the TLR1 gene displayed the role of compound heterozygosity in modulating the phenotypic expression and penetrance of RA. The structural and functional consequences of the TLR1 missense single nucleotide mutations (Cys442→Arg442; Ile679→Thr679) were evaluated through molecular dynamic simulation (MDS) studies. Analysis showed domain's rigidification, conferring stability to mutant TLR1-TIR/TIRAP-TIR complex with concomitant increase in molecular interactions with pro-inflammatory cytokines, compared to the wild-type conformation. Gene co-expression network analysis highlighted interlinked partnering genes along with interleukin-6 production of TLR1 (corrected p-value 2.98e-4) and acetylcholine receptor activity of CHRNG (corrected p-value 6.12e-2) as highly enriched associated functions.

CONCLUSION

The results, validated through case-control study subjects, suggested that the variants identified through WES and confirmed through Sanger sequencing and MDS are the novel disease variants and are likely to confer RA-susceptibility, independently and/or in a family-specific context. Key Points • Exploration of population based/ethno-specific big data is imperative to identify novel causal variants of RA. • Two new deleterious missense mutations in mutational hotspot exon 4 of TLR1 gene have been identified in Pakistani RA patients. • MD simulation data provides evidence for domain's rigidification, conferring stability to mutant TLR1-TIR/TIRAP-TIR complex, with concomitant increase in production of pro-inflammatory cytokines, thus adding to the onset/erosive outcome of RA.

Interferon-gamma (IFN-γ) intronic variant (rs2430561) is a risk factor for systemic lupus erythematosus: Observation from a meta-analysis

BACKGROUND

The role of interferon-gamma (IFN-γ) in autoimmune disorders has been well documented. Elevated levels of IFN-γ are observed in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) and are linked with disease severity. Single nucleotide polymorphism in the intronic region of the IFN-γ gene (+874 T>A rs2430561) has been associated with susceptibility to the development of RA and SLE; however, the reports remained contradictories. We conducted a meta-analysis using earlier published articles to reach a valid conclusion on the role of IFN-γ polymorphism (+874 T>A) in autoimmune diseases.

MATERIALS AND METHODS

Various online databases such as PubMed, Google Scholar, Science Direct, and Scopus were searched to find eligible reports for inclusion in the present analysis. Two independent authors extracted eligible studies and data. The meta-analysis was performed by comprehensive meta-analysis software (CMA) v.3.1. Trial sequential analysis was performed to test whether enough case-control studies have already been conducted worldwide to reach a valid observation.

RESULTS

Six published reports on the role of IFN-γ +874 T>A in SLE and four in RA were found after searching various databases. However, out of those six studies in SLE, in one study, the distribution of genotypes was not following the hardy-Weinberg equilibrium. In RA, three studies were deviated out of four reports. Thus, a total of five studies comprising 1440 SLE patients and 1748 controls were considered for the present meta-analysis. Meta-analysis showed a significant association between IFN-γ +874 T>A variants with susceptibility to SLE (homozygous comparison: p = 0.036, OR = 1.592, heterozygous model: p = 0.042, OR = 1.507, dominant model: p = 0.002, OR = 1.309).

CONCLUSIONS

IFN-γ +874 T>A variant is associated with predisposition to SLE development.

Association between the interferon-γ +874 T/A polymorphism and susceptibility to systemic lupus erythematosus and rheumatoid arthritis: A meta-analysis

We aimed to determine whether the interferon (IFN)-γ +874 T/A polymorphism (rs2430561) is associated with susceptibility to systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). A meta-analysis was conducted to assess the association between the IFN-γ +874 T/A polymorphism and SLE or RA using allele contrast, homozygous contrast, recessive, and dominant models. A total of nine studies (six on SLE and three on RA), involving 1839 patients and 2272 controls, were included in the meta-analysis. The meta-analysis revealed a significant association between SLE and the TT genotype of the IFN-γ +874 T/A polymorphism (odds ratio [OR] = 0.751, 95% confidence interval [CI] = 0.634-0.899, p = .001), and stratification by ethnicity indicated an association between the IFN-γ +874 TT genotype and the Asian population. The analysis also revealed a significant association between SLE and the TT + TA genotype of the IFN-γ +874 T/A polymorphism in Arab populations (OR = 1.598, 95% CI = 1.053-2.425, p = .028). However, no association between the IFN-γ +874 T/A polymorphism and RA was found using allele contrast, recessive, dominant or homozygous contrast models in all study subjects and ethnic groups. This meta-analysis demonstrated that the IFN-γ +874 T/A polymorphism is associated with susceptibility to SLE in Asian and Arab populations.

Interleukin-18 in Brazilian Rheumatoid Arthritis Patients: Can Leflunomide Reduce It?

OBJECTIVES

Rheumatoid arthritis affects about 1% of the world's population. This is a chronic autoimmune disease. It is predominant in females with progressive joint damage. Immune cells are involved, especially Th1/Th17 lymphocytes and their inflammatory cytokines. These proteins have different functions in the immune system, such as IL-16 is a chemotactic factor; IL-18 can activate NFκB transcription producing inflammatory proteins; IL-31 can activate the JAK/STAT pathway which leads to the production of inflammatory factors in chronic diseases; IL-33 promotes IL-16 secretion which causes lymphocyte recruitment, and IL-32 and IL-34 appear to increase TNF secretion by macrophages activation in AR. The aim of this study was to evaluate serum levels of IL-16, IL-18, IL-31, IL-32, IL-33, and IL-34 and compare them with the severity and treatment of RA patients if there are any correlations.

METHODS

A total of 140 RA patients and 40 healthy donors were recruited from the Department of Rheumatology at Hospital das Clínicas from the Federal University of Pernambuco. 60 AR patients were naïve for any treatment. Serum cytokine levels were determined using an ELISA kit.

RESULTS

Serum IL-16 (p = 0.0491), IL-18 (p < 0.0001), IL-31 (p = 0.0004), and IL-32 (p = 0.0040) levels were significantly increased in RA patients compared with healthy donors. It was observed that patients using leflunomide had the lowest IL-18 levels, close to controls levels (p = 0.0064).

CONCLUSION

IL-16, IL-18, IL-31, and IL-32 are increased in the serum of RA patients. IL-18 is at lower levels in those AR who are taking leflunomide as treatment.

Usefulness of Cytokine Gene Polymorphisms for the Therapeutic Choice in Japanese Patients with Rheumatoid Arthritis

Background

Rheumatoid arthritis (RA) is characterized by systemic synovitis with bone erosion and joint cartilage degradation. Although the analysis of polymorphisms in cytokine-encoding genes is important or understanding the pathophysiology of RA and selecting appropriate treatment for it, few studies have examined such single-nucleotide polymorphisms (SNPs) specifically in Japanese patients. This study was established to investigate the associations between polymorphisms in cytokine-encoding genes, autoantibodies and therapeutic responses in Japanese RA patients.

Methods

The subjects in this study consisted of 100 RA patients and 50 healthy controls. We extracted data on sex, age, disease duration, rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibody, and therapeutic responses, including to methotrexate (MTX) and biological disease-modifying antirheumatic drugs (DMARDs). Genomic DNA was isolated from peripheral blood, which was genotyped for IL-10, TNF-α, TGF-β₁, and IFN-γ polymorphisms.

Results

Regarding IL-10 (−592 C/A and −819 C/T), significant decreases in the frequencies of the IL-10 (−592) CC genotype and (−819) CC genotype were found in RA patients compared with the levels in controls. For IFN-γ (+874 T/A), a significant decrease in the frequency of the TT genotype was found in RA patients compared with that in controls. Regarding TGF-β₁ (+869 T/C), patients with positivity for anti-CCP antibody had a significantly lower frequency of the CC genotype than those with negativity for it. Furthermore, the IL-10 (−592) CC genotype and (−819) CC genotype might be related to the biological DMARD-response.

Conclusion

Our results suggest that the analysis of polymorphisms in cytokine-encoding genes may be useful when selecting treatment for Japanese RA patients.

IL1β, IL18, NFKB1 and IFNG gene interactions are associated with severity of rheumatoid arthritis: A pilot study

Rheumatoid arthritis (RA) is an autoimmune disease which can lead to progressive and functional disability. Literature data suggest that some inflammatory proteins are dysregulated in RA patients and its genetic polymorphisms may contribute to the aetiology and pathogenesis of disease in different ethnic groups. Polymorphisms in IL1β, IL18, NFKB1 and IFNG genes were studied in different populations with RA, but the analysis indicated contradictory results. Thereby, we hypothesised that polymorphisms in these genes could have a combined effect on susceptibility to and severity of disease. We evaluated the +3953 C/T IL1β (rs1143634), -137 G/C IL18 (rs187238), -94 ins/del ATTG NFKB1 (rs28362491) and +874 T/A IFNG (rs2430561) polymorphisms in the northeastern Brazilian population. Peripheral blood samples were collected and DNA extraction was conducted. The polymorphisms were evaluated by RFLP and ARMS-PCR. An association was observed in rs1143634 which showed a protective effect against development of RA in carriers of the T allele (OR = 0.58; 95% CI 0.36-0.92; p = .020). In addition, we found an association among genotypes of the rs1143634 with the HAQ index (p = .021) and rs2430561 with DAS28 (p = .029) and CDAI (p = .029). In relation to combined effects of these SNPs (C/C to rs1143634, G/G to rs187238, I/I to rs28362491 and AA to rs2430561) we found a significant association with decreased functional disability (HAQ index p < .001) and ESR (p = .034), indicating a lower disease activity in carriers of these genotypes. GLM analysis confirmed these associations (HAQ (F = 5.497; p < .001) and ESR (F = 2.727; p = .032)). Our analysis indicated that in the studied population +3953 C/T IL-1β (rs1143634), -137 G/C IL-18 (rs187238), -94 ins/del ATTG NFKB1 (rs28362491) and +874 T/A IFNG (rs2430561) polymorphisms can together contribute to RA severity although they do not individually influence the disease.

Association Between the Interferon Gamma 874 T/A Polymorphism and the Severity of Valvular Damage in Patients with Rheumatic Heart Disease

Interferon gamma (IFN-γ) is a multifunctional cytokine that plays an important role in modulating almost all phases of the immune response and may be responsible for the increased valvular fibrosis and calcification in the pathogenesis of rheumatic heart disease (RHD). The aim of this study was to investigate the possible relationship between the IFN-γ +874 T/A polymorphism and the severity of valvular damage in the Turkish population. The IFN-γ genotypes were determined in 152 RHD patients and 151 healthy controls by ARMS-PCR. Differences in genotype distribution between patients with RHD and control were evaluated by the χ² test. All statistical analyses were performed with SPSS 15.0 Software program. Frequency of the AA genotype was found to be significantly lower and the TT genotype significantly higher in the RHD group compared to controls (p = 0.002 and p = 0.018, respectively). The TT genotype was found to be significantly higher (26.8% vs. 9.1%, p = 0.009) and the AA genotype significantly lower (29.1% vs. 8.2%, p = 0.001) in the severe valvular disease (SVD) group compared to mild valvular disease group. In the SVD group, 79 patients had mitral balloon valvotomy and/or mitral valve replacement and had significantly higher TT genotype compared to patients with medical follow-up (30.4% vs. 19%, p = 0.001). The data demonstrated that TT genotype is associated with both RHD and the severity of RHD.

Hepatitis B vaccine non response: A predictor of latent autoimmunity?

Unresponsiveness to Hepatitis B virus (HBV) vaccine has been associated with interleukins involved with Th1 functioning including Interleukin-8 (IL-18) and Interferon-γ (IFN-γ). IL-18 and IFN-γ have also been implicated in the onset of different types of immune-mediate inflammatory conditions such as Type 1 Diabetes (T1D), Celiac disease (CD), rheumatoid arthritis (RA), obesity and systemic lupus erythematosus (SLE). Taking into account that HBV vaccination is provided in the 1st year of life worldwide, I propose that all babies should be tested for anti-HBs response after completion of the vaccine series. And I suggest that children with undetectable anti-HBs titers after recommended immunization schedule as well as the additional booster doses should be followed up over time because they may be at risk of developing a number of autoimmune disorders. In this light, the non-responsiveness to HBV vaccine might be a predictor of latent autoimmunity. For that reason, research studies are needed in order to verify the existence of potential IL-18 and IFN-γ gene polymorphisms to utilize as biomarkers of latent autoimmunity. As a final point, administration of neutralizing antibodies against IFN-γ and/or IL-18 might represent a future target for immune-modulatory therapeutic approach to halt or even reverse autoimmune phenomena.

Major involvement of bacterial components in rheumatoid arthritis and its accompanying oxidative stress, systemic inflammation and hypercoagulability

We review the evidence that infectious agents, including those that become dormant within the host, have a major role to play in much of the etiology of rheumatoid arthritis and the inflammation that is its hallmark. This occurs in particular because they can produce cross-reactive (auto-)antigens, as well as potent inflammagens such as lipopolysaccharide that can themselves catalyze further inflammagenesis, including via β-amyloid formation. A series of observables coexist in many chronic, inflammatory diseases as well as rheumatoid arthritis. They include iron dysregulation, hypercoagulability, anomalous morphologies of host erythrocytes, and microparticle formation. Iron dysregulation may be responsible for the periodic regrowth and resuscitation of the dormant bacteria, with concomitant inflammagen production. The present systems biology analysis benefits from the philosophical idea of "coherence," that reflects the principle that if a series of ostensibly unrelated findings are brought together into a self-consistent narrative, that narrative is thereby strengthened. As such, we provide a coherent and testable narrative for the major involvement of (often dormant) bacteria in rheumatoid arthritis.

Association of genetic polymorphisms in interferon-γ, interleukin-6 and transforming growth factor-β1 gene with oral lichen planus susceptibility

BACKGROUND

Oral lichen planus (OLP) is a premalignant mucocutaneous disease in which genetic factors and immune responses play a major role. Cytokines play an important role in the pathogenesis and disease progression of OLP. The aim of this study was to investigate the impact of gene polymorphisms of T helper cell subtype Th1 and Th2 cytokines, interferon-gamma (IFN-γ), interleukin-6 (IL-6) and transforming growth factor (TGF)-β1 on OLP susceptibility in a Saudi cohort.

METHODS

Forty two unrelated patients with OLP and 195 healthy controls were genotyped for IFN-γ (874A/T), IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms.

RESULTS

The frequency of genotype AT of IFN-γ (874A/T) was significantly higher while genotype AA was lower in OLP patients as compared to controls (P < 0.05). The frequency of T containing genotypes (AT + TT) was also higher in OLP patients as compared to that in controls (P = 0.003). The frequencies of allele T was higher while that of allele A lower in patients than the controls however the difference was not statistically significant (P = 0.07). There was no significant difference in the frequencies of alleles and genotypes of IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms between patient and control groups. These results indicated that genotype AT of IFN-γ (874A/T) polymorphism is associated with OLP risk and genotype AA is protective to OLP. On the other hand the polymorphisms IL-6 (174G/C) and TGF-β1 (509C/T) may not be associated with OLP risk in our population.

CONCLUSION

It is concluded that IFN-γ (874A/T) polymorphism is associated with the susceptibility of OLP, however further studies with large sample size involving different ethnic populations should be conducted to strengthen our results.

Interleukin 12B gene polymorphisms and susceptibility to rheumatoid arthritis: a data synthesis

The aim of this study was to investigate the association of two common interleukin 12B (IL-12B) polymorphisms (rs3212227 and rs6887695) with rheumatoid arthritis (RA) susceptibility through meta-analyses. A systematic literature search of PubMed, Web of Science, Cochrane Library, and Embase databases was conducted on articles published before 28 February 2016. Then odds ratio (OR) with 95 % confidence interval (CI) was used to quantify the strength of association for homozygote, heterozygote, dominant, and recessive genetic models. Nine articles with a total of 17 case-control studies (12 for IL-12B rs3212227 polymorphism and 5 for IL-12B rs6887695 polymorphism) met our inclusion criteria. The pooled results demonstrated that IL-12B rs3212227 (homozygote model: OR = 0.96, 95 % CI = 0.81-1.15; heterozygote model: OR = 1.07, 95 % CI = 0.93-1.23; dominant model: OR = 1.05, 95 % CI = 0.91-1.20; recessive model: OR = 0.93, 95 % CI = 0.79-1.10) and rs6887695 (homozygote model: OR = 1.01, 95 % CI = 0.84-1.21; heterozygote model: OR = 1.14, 95 % CI = 0.86-1.51; dominant model: OR = 1.14, 95 % CI = 0.87-1.48; recessive model: OR = 1.01, 95 % CI = 0.85-1.21) polymorphisms may not be associated with RA risk. Our meta-analyses demonstrated that IL-12B rs3212227 and rs6887695 polymorphisms do not confer susceptibility to RA.

Association of IL12B Gene Polymorphisms with Rheumatoid Arthritis: A Meta-analysis

BACKGROUND AND AIMS

Currently published papers regarding the relationship between interleukin (IL)-12B gene polymorphisms and rheumatoid arthritis (RA) are contradictory. The aim of this meta-analysis was to evaluate the associations between the IL-12B gene polymorphisms (rs3122227 and rs6887695) and RA risk.

METHODS

We searched PubMed, Embase, the Cochrane Library and the China Knowledge Resource Integrated Database. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to assess associations between IL12B gene polymorphisms and RA.

RESULTS

A total of eight publications (4,409 cases and 5,591 controls) were included in this meta-analysis. The results demonstrated that rs3122227 and rs6887695 were not associated with RA risk based on current included studies. However, stratification analyses indicated rs6887695 was associated with RA in Asian patients. Rs3122227 was not related with RA in Asian or Caucasian patients.

CONCLUSIONS

Our data indicated that IL-12B gene polymorphisms were not related with RA. However, rs6887695 was associated with RA in Asian patients. Further larger-scale studies are urgently needed to identify the association between IL-12B gene polymorphisms and RA in Asian populations.

Relationship between the IL12B (rs3212227) gene polymorphism and susceptibility to multiple autoimmune diseases: A meta-analysis

OBJECTIVES

The purpose of this study was to evaluate whether a single-nucleotide polymorphism (SNP) IL12B 3(')UTR +1188A/C (rs3212227) confers susceptibility to several autoimmune diseases.

METHODS

A systematic literature search was conducted to identify relevant studies. Pooled odds ratio (OR) with 95% confidence interval (CI) was used to estimate the strength of association.

RESULTS

Twenty-five studies were included in the meta-analysis, which contained 9794 cases and 11,330 controls. Our result indicated that IL12B +1188A/C (rs3212227) polymorphism was associated with type-1 diabetes (T1D) in the dominant model (p = 0.008), and an increased risk was found in East Asians in the dominant model (p < 0.001). East Asians rheumatoid arthritis (RA) patients seemed to be at risk of allelic model (p = 0.011). As to Behcet's disease (BD), there was a risk in dominant model (p = 0.020) and positive associations of dominant model, allelic model in East Asians (p = 0.009; p < 0.001, respectively). But we failed to find any association between IL12B +1188A/C (rs3212227) polymorphism with Graves' disease (GD) and ankylosing spondylitis (AS).

CONCLUSIONS

The present study suggests that the IL12B +1188A/C (rs3212227) polymorphism might be associated with genetic susceptibility to autoimmune diseases, such as T1D, RA, BD, but not GD and AS.

Association between interferon-γ +874 T/A polymorphism and susceptibility to autoimmune diseases: a meta-analysis

OBJECTIVE

The aim of this study was to explore whether the interferon (IFN)-γ +874 T/A polymorphism plays a role in modifying the risk of autoimmune diseases.

METHODS

A meta-analysis was conducted on the association between the IFN-γ +874 T/A polymorphism and autoimmune diseases.

RESULTS

Eighteen studies with a total of 2952 patients and 3832 controls were included in the meta-analysis. The meta-analysis revealed no association between autoimmune diseases and the IFN-γ +874 T allele in all study subjects (odds ratio (OR)=1.023, 95% confidence interval (CI) = 0.894-1.171, p = 0.738), but stratification by ethnicity indicated an association between the IFN-γ +874 T allele and autoimmune diseases in Latin American subjects (OR = 0.780, 95% CI = 0.629-0.953, p = 0.015). Meta-analysis also revealed an association between autoimmune diseases and the IFN-γ +874 T/A polymorphism in Caucasian and Middle Eastern subjects under a dominant inheritance model (OR = 0.686, 95% CI = 0.489-0.964, p = 0.003; OR = 1.414, 95% CI = 1.102-1.813, p = 0.006). Meta-analysis by autoimmune disease type indicated an association between ITP and the IFN-γ +874 T allele (OR = 1.753, 95% CI = 1.228-2.503, p = 0.002), but not for vasculitis, vitiligo, and auto-immune thyroid disease. Meta-analysis also showed a significant association between the IFN-γ +874 T/A polymorphism and systemic lupus erythematosus (SLE) under the dominant model (OR = 1.668, 95% CI = 1.114-2.497, p = 0.013).

CONCLUSIONS

This meta-analysis indicates that the IFN-γ +874 T/A polymorphism may play a significant role in modifying the risk of autoimmune diseases in Caucasian, Latin American, and Middle Eastern subjects, and in particular shows that the IFN-γ +874 T/A polymorphism is associated with increased genetic susceptibility to idiopathic thrombocytopenic purpura and SLE.