Interleukin (IL)-23 Receptor, IL-17A and IL-17F Gene Polymorphisms in Brazilian Patients with Rheumatoid Arthritis

Association of Interleukin 23 Receptor Polymorphisms with Predisposition to Rheumatoid Arthritis: An Updated Meta and Trial Sequential Analysis

The etiology of Rheumatoid Arthritis (RA) development remained unclear, and several factors, such as environmental, genetic, and immune system dysfunction, have been attributed to the susceptibility. Interleukin 23 (IL23) induces expansion of the Th17 cells through the IL-23 receptor (IL-23R) and believes in playing a major role in RA pathogenesis. Various genetic mutants in the IL23R gene (rs10489629, rs1343151, rs2201841, rs7517847, rs1004819, rs10889677, rs11209026, rs7530511) have been associated with the susceptibility RA, but results are contradictories. We performed a meta-analysis to establish the association of IL23R polymorphisms with susceptibility RA. For the meta-analysis, a detailed search of databases like Google Scholar, PubMed, Scopus, Web of Science, and Science Direct was conducted, and data were extracted from the included reports. The meta-analysis was performed by the Comprehensive Meta-Analysis v3 software. A significant association of IL-23R rs11209026 (AA vs. GG: Odds ratio = 2.250, p-value = 0.01; AA vs. GG+GA: Odds ratio = 2.271, p-value = 0.01), rs1343151 (A vs. G: Odds ratio = 1.091, p-value = 0.001; AA vs. GG: Odds ratio = 1.209, p-value = 0.001; GA vs. GG: Odds ratio = 1.116, p-value = 0.004; AA+GA vs. GG: Odds ratio = 1.135, p-value = 0.000; AA vs. GG+GA: Odds ratio = 1.144, p-value = 0.012) and rs10889677 (CA vs. CC: Odds ratio = 1.375, p-value = 0.041) polymorphisms were observed with increased susceptibility for the development of RA. In contrast, IL-23R rs10489629 (G vs. A: odds ratio = 0.901, p-value = 0.047, GG vs. AA: Odds ratio = 0.763, p-value = 0.022, GG vs. AA+AG: Odds ratio = 0.852, p-value = 0.00) and IL23R rs2201841 (CC vs. TT+TC: Odds ratio = 0.826, p-value = 0.026) variants were linked with protection against the development of RA. In addition, the trial sequential analysis revealed the inclusion of a sufficient number of studies in the present meta-analysis, and no further additional studies are required. IL-23R variants are associated with genetic susceptibility or resistance against the development of RA.

Pharmacogenomics of Monoclonal Antibodies for the Treatment of Rheumatoid Arthritis

Precision medicine refers to a highly individualized and personalized approach to patient care. Pharmacogenomics is the study of how an individual’s genomic profile affects their drug response, enabling stable and effective drug selection, minimizing side effects, and maximizing therapeutic efficacy. Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation in the joints. It mainly starts in peripheral joints, such as the hands and feet, and progresses to large joints, which causes joint deformation and bone damage due to inflammation of the synovial membrane. Here, we review various pharmacogenetic studies investigating the association between clinical response to monoclonal antibody therapy and their target genetic polymorphisms. Numerous papers have reported that some single nucleotide polymorphisms (SNPs) are related to the therapeutic response of several monoclonal antibody drugs including adalimumab, infliximab, rituximab, and tocilizumab, which target tumor necrosis factor (TNF), CD20 of B-cells, and interleukin (IL)-6. Additionally, there are some pharmacogenomic studies reporting on the association between the clinical response of monoclonal antibodies having various mechanisms, such as IL-1, IL-17, IL-23, granulocyte-macrophage colony-stimulating factor (GM-CSF) and the receptor activator of nuclear factor-kappa B (RANK) inhibition. Biological therapies are currently prescribed on a “trial and error” basis for RA patients. If appropriate drug treatment is not started early, joints may deform, and long-term treatment outcomes may worsen. Pharmacogenomic approaches that predict therapeutic responses for RA patients have the potential to significantly improve patient quality of life and reduce treatment costs.

Associations between IL-23R gene polymorphism (rs10889677 A/C) and ankylosing spondylitis and rheumatoid arthritis susceptibility: A meta-analysis with trial sequential analysis

OBJECTIVES

Autoimmune diseases are a kind of chronic diseases for which the immune system loses tolerance to autoantigens. This meta-analysis' purpose is to determine whether there exists a correlation between IL-23R polymorphism and common autoimmune diseases like ankylosing spondylitis (AS) and rheumatoid arthritis (RA).

METHODS

We searched the relevant literatures up to September 2021 and used different effect models for meta-analysis. 95% confidence interval (95% CI) and odds ratio (OR) were used to determine the relationship between rs10889677 (A/C) polymorphism and AS as well as RA. Finally, to promote the reliability of results, the trial sequential analysis (TSA) has also been applied and we searched the data related to autoimmune diseases (AS, RA) on genome-wide association studies (GWAS).

RESULTS

Generally, 31 studies were included. Rs10889677 (A/C) was significantly correlated with the susceptibility to AS and RA among the general individuals (p < .05). Moreover, there existed a relevance between allele A and AS as well as RA in Caucasians (p < .05). AA genotype increased the risk of autoimmune diseases in Mongolians. As a result, the robustness of meta-analysis has further been proved by TSA.

CONCLUSION

IL-23R (rs10889677 A/C) A allele was a risk gene for AS and RA in the general population, especially in Caucasians. AA genotype increased the risk of AS and RA in Mongolians.

Proinflammatory Cytokines (IL-1, -6, -8, -15, -17, -18, -23, TNF-α) Single Nucleotide Polymorphisms in Rheumatoid Arthritis-A Literature Review

Conducted studies highlight that a mixture of genetic and environmental factors is responsible for rheumatoid arthritis (RA) development. This study aimed to analyze the available literature for the relationship between, on the one hand, single-nucleotide polymorphisms (SNPs) in the proinflammatory cytokines genes interleukin-1 (IL-1), -6, -8, -15, -17, -18, and -23, and tumor necrosis factor-alpha (TNF-α), and on the other hand, RA susceptibility, severity, and patients' response to applied treatment. The PubMed database was searched for sources. Preference was given to articles which were published within the past 20 years. Data indicate that the relationship between selected SNPs in proinflammatory cytokines genes and susceptibility to developing RA is inconclusive, and it depends on the ethnicity of the population. Although the allelic and genotypic frequencies of many SNPs in proinflammatory cytokines genes analyzed did not differ between RA patients and healthy controls, deeper analysis showed that these polymorphisms have a relationship with clinicopathological features of RA. SNPs in proinflammatory cytokines genes also "modify patients' response" to applied treatment. Further studies, on larger cohorts of subjects and in different populations, should be conducted to elucidate the role of SNPs in IL-1, -6, -8, -15, -17, -18, and -23, and TNF-α genes in RA patients.

Association between the interleukin (IL)-17A rs2275913 polymorphism and rheumatoid arthritis susceptibility: a meta-analysis and trial sequential analysis

Objective

This meta-analysis was conducted to investigate the relationship between the interleukin (IL)-17A rs2275913 polymorphism and rheumatoid arthritis (RA) susceptibility.

Methods

Eligible studies were retrieved from PubMed, Embase, and Web of Science. The fixed- or random-effects model was used to calculate the pooled odds ratios (ORs) and 95% confidence intervals (95%CIs) on the basis of heterogeneity.

Results

Overall, 11 studies containing 4019 RA patients and 4137 controls were included in this meta-analysis. The results suggested a significant association between the IL-17A rs2275913 polymorphism and RA susceptibility in the overall population (allelic model A vs. G: OR = 0.89, 95%CI: 0.83–0.95; heterozygote model GA vs. GG: OR = 0.87, 95%CI: 0.78–0.96; homozygote model AA vs. GG: OR = 0.82, 95%CI: 0.71–0.96; dominant model GA + AA vs. GG: OR = 0.86, 95%CI: 0.78–0.94). In the subgroup analyses, the IL-17A rs2275913 polymorphism was significantly associated with RA risk in Europeans (allelic model A vs. G: OR = 0.87, 95%CI: 0.78–0.97; heterozygote model GA vs. GG: OR = 0.79, 95%CI: 0.68–0.93; dominant model GA + AA vs. GG: OR = 0.79, 95%CI: 0.68–0.92), but not in Africans or Americans.

Conclusion

This study suggests that the IL-17A rs2275913 polymorphism is significantly associated with RA susceptibility in Europeans.

INPLASY registration number: INPLASY202170056.

Polymorphisms within Genes Coding for IL-17A and F and Their Receptor as Clinical Hallmarks in Ankylosing Spondylitis

IL-17A and IL-17F together with their coreceptor (IL-17RA/RC) were reported to play a significant role in the pathogenesis of spondyloarthritis. The group of axial spondyloarthritis comprises ankylosing spondylitis (AS), a rheumatic disease characterized by chronic inflammation of the joints in the spine. This study is aimed at investigating IL-17A, IL-17F, IL-17RA, and IL-17RC polymorphisms as potential biomarkers of disease susceptibility, clinical parameters, and anti-TNF treatment outcome in a cohort of Polish ankylosing spondylitis patients. In total, 328 subjects, including 138 AS patients and 190 healthy volunteers, participated in the study. Genotyping of IL-17A rs2275913 (G/A), IL-17F rs763780 (A/G), IL-17RA rs4819554 (A/G), and IL-17RC rs708567 (G/A) was performed on real-time PCR instrument using LightSNiP assays. No significant differences were revealed in genotype and allele distribution between patients and controls despite the association of the IL-17RC rs708567 AA homozygosity with the earlier onset of the disease. Moreover, some relationships between IL-17F rs763780 and IL-17RA rs4819554 polymorphisms with clinical parameters related to the disease activity and anti-TNF treatment outcome were observed. IL-17F rs763780 G allele was found to be associated with high disease activity and BASDAI after 6 months and poor response to the treatment while higher VAS values were more common among IL-17RA rs4819554 G variant carriers. In conclusion, the IL-17F rs763780 polymorphism should be considered as a promising biomarker of disease activity and anti-TNF treatment outcome. The IL-17RA rs48419554 G allele may serve as a potential marker of disease severity in Polish AS patients.

IL-17F promotes osteoblastic osteogenesis via the MAPK/ERK1/2 signaling pathway

Osteoimmunology is a field that focuses on the interactions between the skeletal and immune systems, and has become a focus of research over the years. The role of interleukin (IL)-17F, a proinflammatory cytokine, in bone regeneration and its signal transduction are not completely understood. The aim of the present study was to evaluate the function of IL-17F and the possible mechanisms underlying IL-17F in osteoblasts in vitro. Osteoblasts derived from newborn rats were treated with various concentrations of IL-17F. The pro-osteogenic effects of IL-17F were assessed at the cellular and molecular level. The results demonstrated that IL-17F promoted osteoblast proliferation, differentiation and mineralization. Reverse transcription-quantitative PCR and western blotting indicated that IL-17F treatment upregulated osteogenesis-related factors, including bone morphogenetic protein-2, Runt-related transcription factor-2 (Runx2) and Osterix, and downregulated Noggin compared with the control group. Subsequently, whether the IL-17F receptors, IL-17 receptor (IL-17R) A and IL-17RC, served a role in the effects of IL-17F on osteoblasts was investigated. The mRNA expression levels of IL-17RA and IL-17RC were upregulated in IL-17F-treated osteoblasts compared with control osteoblasts. Furthermore, U0126, a MAPK/ERK1/2 inhibitor, was utilized to investigate the mechanisms underlying IL-17F. The results indicated that compared with the control group, IL-17F increased the protein expression of phosphorylated-ERK1/2, Runx2 and Osterix, whereas U0126 reversed IL-17F-mediated effects. Collectively, the results of the present study suggested that IL-17F promoted osteoblastic osteogenesis via the MAPK/ERK1/2-mediated signaling pathway. IL-17F promoted osteogenesis, including proliferation, differentiation and mineralization activity, indicating that IL-17F may serve as a potential therapeutic target for osteoblast-mediated bone loss disease.

Association of interleukin-17 gene polymorphisms with the onset of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is an autoimmune disorder where multiple cytokines including IL-17A and IL-17F produced by T helper cell 17 (Th17), contribute to its pathogenesis. By initiating inflammatory responses in joints Th17 act as pathogenic driver leading to bone and cartilage destruction in RA patients. Hence, the planned study was aimed to estimate IL-17 gene polymorphism association with RA susceptibility in Pakistani population. The present study included 100 subjects (50 RA patients and 50 healthy controls). Blood samples were taken and DNA was isolated for genotyping purpose. Chi square and Logistic regression analysis was performed to check the association of selected SNPs with RA. For rs2397084 and rs763780 polymorphism T allele acted as significant risk factor as compared to the reference C allele. TT vs. CC comparison in rs2397084 showed that T allele is a risk factor (OR 5.538; 95%Cl 1.757-17.458) in RA susceptibility. In case of rs763780 heterozygous CT (OR 10.80; 95% Cl 3.736-31.218) and homozygous mutant TT (OR 7.50; 95% Cl 2.360-23.831) genotypes proved to be a potential risk for RA patients. The significant differences in allelic and genotypic frequencies were observed for both SNPs. While for rs2275913 significantly varied frequency was observed only for dominant model of inheritance and non significant differences were seen at allelic level. Variation at all these three polymorphic sites substituted mutant amino acids leading to further functional changes in protein structure. Three polymorphic sites rs2275913, rs763780 and rs2397084 positioned on IL-17 gene were significantly strong factors in RA incidence among Pakistani population as they alter normal function of inflammatory cytokine IL-17.

Association between IL-17A and IL-17F gene polymorphism and susceptibility in inflammatory arthritis: A meta-analysis

OBJECTIVES

The association between Interleukin (IL)-17A and IL-17F gene polymorphism with inflammatory arthritis were inconsistent among previous studies. This meta-analysis aimed to determine the association between IL-17A and IL-17F gene polymorphism with ankylosing spondylitis (AS), osteoarthritis (OA) and rheumatoid arthritis (RA).

METHODS

We searched Medline up to August 2019. The summary Odds Ratio (OR) with corresponding 95% confidence intervals (CIs) was calculated to evaluate the relationship between IL-17A and IL-17F gene polymorphism with genetic susceptibility of AS, OA and RA.

RESULTS

A total of 19 studies with 5298 cases and 5675 healthy controls were included. There were significant associations between rs2275913 G allele with OA, RA susceptibility (P < .05) but not AS. Subgroup analysis by ethnicity indicated that rs763780 C allele was closely related to AS and OA in Caucasian populations (P < .001) but not Mongolians. A significant association between rs763780 and RA susceptibility was detected in Caucasian populations (P < .05).

CONCLUSION

IL-17F gene rs763780 C allele confers increased risk of inflammatory arthritis in Caucasians; IL-17A gene rs2275913 G allele are protective for OA susceptibility in Mongolians. More well-designed studies with larger sample size are needed to elucidate the role of IL-17A gene rs2275913 G allele in inflammatory arthritis, especially AS.

IL-17, IL-21 and IL-22 polymorphisms in rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUND

Rheumatoid Arthritis (RA) is an autoimmune systemic disease and in its pathogenesis participate several proinflammatory cytokines, including those produced by Th17 cells. We performed a systematic review aiming to assess the associations between polymorphisms in Th17 cytokines, namely IL-17A, IL-17F, IL-21 and IL-22, and susceptibility to RA.

METHODS

We searched three electronic databases (MEDLINE, Scopus and Web of Science) for observational studies assessing the association between susceptibility to RA (or its clinical presentation) and polymorphisms of the cytokines IL-17A, IL-17F, IL-21 and IL-22. From the selected studies, we extracted information on the studied polymorphisms, assessed outcomes, and demographic characteristics of participants. We performed random effects meta-analyses assessing the associations between susceptibility to RA and different genotypes of the IL-17A rs2275913, IL-17Frs763780 andIL-17Frs2397084polymorphisms. Primary studies' quality was assessed using the Q-Genie tool.

RESULTS

Fifteen studies were included in this systematic review. Five IL-17A polymorphisms were reported to be associated with susceptibility to RA. For the IL-17A rs2275913 polymorphism, our meta-analysis showed the AA genotype to be significantly associated with lower susceptibility to RA(OR = 0.76; 95%CI = 0.61-0.93;p = 0.01), while the opposite was observed for the GG genotype (OR = 1.20; 95%CI = 1.06-1.35;p = 0.01). Concerning IL-17Frs763780 polymorphism, theTT genotype was found to be significantly less frequent in RA patients(OR = 0.49; 95%CI = 0.31-0.77;p = 0.002), while the opposite was observed for the CT genotype (OR = 2.00; 95%CI = 1.03-3.87;p = 0.04). No significant associations were found regarding rs2397084polymorphisms. For IL-21, rs6822844 and rs4505848 were described to have significant associations with susceptibility to RA. No studies were found assessing IL-22 polymorphisms in RA.

CONCLUSIONS

IL-17A rs2275913 and IL-17F rs763780 polymorphisms are significantly associated with susceptibility to RA and with different clinical characteristics of this disease.

Association between interleukin-21 gene rs6822844 polymorphism and rheumatoid arthritis susceptibility

Controversial results concerning the association between a polymorphism rs6822844 in the interleukin (IL) 21 (IL-21) gene and rheumatoid arthritis (RA) have existed. A meta-analysis to confirm above relationships is necessary to be performed immediately. We conducted a search in the PubMed database, covering all papers published up to 20 October 2018. Overall, six case–control studies with 3244 cases and 3431 healthy controls were included. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Publication bias was assessed with both Egger’s and Begg’s tests. After calculation, we found that IL-21 rs6822844 polymorphism could decrease RA risk in overall genetic models (allelic contrast: OR = 0.77, 95% CI = 0.62–0.97, P=0.024; TG versus GG: OR = 0.68, 95% CI = 0.50–0.92, P=0.013, and dominant genetic model: OR = 0.72, 95% CI = 0.55–0.94, P=0.016). Similarly, stratified analysis by race, source of control, significantly decreased association was found in Asians, Caucasians and hospital-based (HB) control source. Finally, in the subgroup analysis of rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) status, poorly decreased relationship was detected between IL-21 rs6822844 polymorphism and RF negative and ACPA positive RA risk, respectively. No obvious evidence of publication bias was detected in overall analysis. In summary, our study indicated that IL-21 rs6822844 polymorphism was significantly associated with decreased RA susceptibility.

Association of Interleukin-17F 7488A/G and 7383A/G Polymorphisms With Rheumatoid Arthritis: A Meta-Analysis

OBJECTIVES

This meta-analysis aims to summarize and estimate the relationship between rheumatoid arthritis (RA) susceptibility and two polymorphisms of interleukin-17F (IL-17F) 7488A/G and 7383A/G.

MATERIALS AND METHODS

PubMed, Embase and Web of Science were searched up to 01 July 2017. Case-control studies with genotype frequencies data for 7488A/G and 7383A/G were included. The pooled effects were calculated by fixed-effect model or random effects model.

RESULTS

A total of seven publications with 1,409 RA patients and 1,303 controls were included in the present meta-analysis. The results indicated that 7488A/G was significantly associated with increased susceptibility to RA (GA vs. AA: odds ratio [OR]=1.43, 95% confidence interval [CI]: 1.07-1.90, p=0.02; GG vs. AA: OR=3.22, 95% CI: 1.54-6.74, p=0.002; GA+GG vs. AA: OR=1.57, 95% CI: 1.02-2.42, p=0.04; GG vs. GA+AA: OR=3.05, 95% CI: 1.46-6.39, p=0.003). In subgroup analysis, 7488A/G was a strong risk factor in Europeans but not in Americans or Africans. No significant association was found between 7383A/G and RA in overall population or ethnic subgroups by all genetic model comparisons.

CONCLUSION

This meta-analysis provided evidence that IL-17F 7488A/G polymorphism is associated with increased RA susceptibility, while no clear correlation was found between 7383A/G and RA.

Are genetic variations in IL-21-IL-23R-IL-17A cytokine axis involved in a pathogenic pathway of rheumatoid arthritis? Bayesian hierarchical meta-analysis

Inflammatory cytokines have been established to be involved in the pathogenesis of rheumatoid arthritis (RA). The genetic polymorphisms in the interleukin (IL) 23 receptor (IL23R), IL21, and IL17 have been associated with RA risk. However, there is no conclusive understanding of the genes encoding the immunoinflammatory IL-21-IL-23R-IL-17A pathway in RA aetiopathogenesis. This meta-analysis was conducted to attain this goal. A comprehensive literature search was conducted in Scopus and PubMed to look for the relevant case-control studies up until 2018. A Bayesian hierarchical meta-analysis was carried out to assess the association between the polymorphisms and the risk of RA. The association was estimated by calculating the logarithm of odds ratio (Log OR) and 95% credible interval (95% CI). In this meta-analysis, 37 case-control studies comprising 23,506 RA patients and 25,984 healthy individuals were found for analyzing the IL23R, IL21, and IL1A gene polymorphism and risk of RA. In the IL23R gene rs1343151 SNP, the minor A allele significantly increased the risk of RA (Log OR = 0.085, 95% CI = 0.008, 0.156). Moreover, the minor AA genotype was significantly associated with increased RA risk (Log OR = 0.176, 95% CI = 0.028, 0.321). In addition, the C allele of the IL23R gene rs2201841 SNP significantly decreased the disease risk (Log OR = -0.544, 95% CI = -1.0, -0.065). Since Bayesian meta-analysis is a powerful strategy to pool the data, it can be mentioned that genetic polymorphisms of IL23R, but not IL21 and IL17A, are involved in susceptibility to RA.

Increased Expression of IL-23 Receptor (IL-23R) in Vogt-Koyanagi-Harada (VKH) Disease

OBJECTIVE

Vogt-Koyanagi-Harada (VKH) disease is an autoimmune disease mediated by T cells that target melanocytes. It has been shown that IL-23 receptor (IL-23R) signaling promotes the generation of pathogenic T helper 17 cells. The aim of this study was designed to detect the possible role of IL-23R in VKH disease.

METHODS

Subjects were divided into an active and inactive VKH patient group and a normal control group. The IL-23R level in peripheral blood mononuclear cells (PBMCs) was measured by flow cytometry and real-time polymerase chain reaction. PBMCs were stimulated with serum from patients or controls to detect the influence of serum from VKH patients on IL-23R expression.

RESULTS

The IL-23R mRNA level was markedly increased in PBMCs from the active VKH patient group as compared to normal controls. Flow cytometry analysis showed that there was also an elevated IL-23R protein level in PBMCs in active VKH patients. The IL-23R protein level was higher in PBMCs obtained from healthy controls when they were cultured with serum from active VKH patient as compared to cell cultured with serum from normal controls. After the intraocular inflammation in VKH patients was controlled, the IL-23R gene expression returned back to normal levels.

CONCLUSION

Our study suggests that an elevated IL-23R level may participate in the development of VKH disease.

Association of IL17 and IL23R gene polymorphisms with rheumatic heart disease in South Indian population

BACKGROUND

IL-23/Th17 signaling pathway plays a crucial role in the cell-mediated immune response against bacterial infections and also in the pathogenesis of inflammatory and autoimmune diseases. Recent studies indicate that Th17 cell-associated cytokines are involved in the progression and maintenance of valvular lesions in rheumatic heart disease (RHD). Variants in the genes of cytokines that are potentially involved in Th17 response may influence interindividual differences in their expression levels, thereby contributing to the pathogenesis of immune-mediated diseases such as RHD.

OBJECTIVE

The aim of the study is to investigate the association of IL17A, IL17F, and IL23R gene variants with the risk perception of RHD.

METHODS

A total of 225 individuals (99 RHD patients and 126 healthy siblings) were recruited for the study. The IL17A (rs2275913), IL17F (rs763780), and IL23R (rs10889677) polymorphisms were determined by polymerase chain reaction restriction fragment length polymorphisms and amplification-refractory mutation system-polymerase chain reaction methods, respectively.

RESULTS

The frequency of IL17A (rs2275913) A/A genotype was significantly high in pooled RHD patients (odds ratio [OR] = 2.76; p_c = 0.021), rheumatic fever (RF) patients (OR = 14.5; p_c = 0.0001), and mitral valvular lesions patients (OR = 2.74; p_c = 0.039) when compared to healthy siblings. However, the IL17F (rs763780) and IL23R (rs10889677) polymorphisms did not show any association with RHD.

CONCLUSIONS

The results suggest that IL17A (rs2275913) polymorphism is associated with the development of RF/RHD in South Indian population. Further studies are required to substantiate the association of these genes with the disease risk.

Influence of TNF and IL17 Gene Polymorphisms on the Spondyloarthritis Immunopathogenesis, Regardless of HLA-B27, in a Brazilian Population

Background and Objectives

Spondyloarthritis (SpA) represents a heterogeneous group of immune-mediated inflammatory diseases that have overlapping clinical features, genetic predisposition, and pathogenic mechanisms. Hence, we investigated, through a case-control study, whether single-nucleotide polymorphisms of TNF and IL17 genes are associated with SpA, ankylosing spondylitis (AS), and psoriatic arthritis (PsA) in a mixed Brazilian population.

Methods

Genotyping of TNF-308 (rs1800629), TNF-238 (rs361525), IL17A (rs2275913), IL17F (rs763780), and HLA-B27 polymorphisms was performed in 243 patients with SpA and 210 controls from Southern Brazil using SSOP-Luminex (One Lambda) and PCR-SSP assays.

Results

Significant associations were confirmed between the HLA-B27 marker and SpA, AS, and PsA diseases. While TNF-308 (rs1800629) AA/GA, IL17A (rs2275913) AA/GA, and IL17F (rs763780) CC/TC genotype frequencies were associated, in the dominance inheritance model, with SpA and AS, regardless of gender, the presence of HLA-B27, TNF-238 (rs361525) GA/AA, IL17A (rs2275913) AA/GA, and IL17F (rs763780) genotypes was associated with PsA.

Conclusion

In this Brazilian population, TNF and IL17 gene polymorphisms responsible for the expression of important inflammatory cytokines were associated with overall SpA, and, specifically, with AS and PsA, regardless of gender and HLA-B27. However, future larger studies with different ethnicities may be necessary to confirm these genetic associations.

IL-17A, IL-17RC polymorphisms and IL17 plasma levels in Tunisian patients with rheumatoid arthritis

Background

Interleukin-17 (IL-17), a cytokine mainly secreted by Th17 cells, seems to play a significant role in the pathogenesis of rheumatoid arthritis (RA). Functional genetic polymorphisms in IL-17 and its receptor genes can influence either qualitatively or quantitatively their functions. Therefore, we aimed to study the impact of IL17-A and IL17RC polymorphisms on plasma level of IL-17 and RA susceptibility and severity.

Methods

In this context, IL-17A*rs2275913 and IL-17RC*rs708567 polymorphisms were investigated together with the quantification of IL17 plasma level in 115 RA patients and 91 healthy control subjects matched in age, sex and ethnic origin.

Results

There were no statistically significant associations between IL-17A and IL-17RC studied polymorphisms and RA susceptibility. In contrast, IL-17A plasma levels were significantly higher in patients (55.07 pg/ml) comparatively to controls (4.75 pg/ml), p<10E-12. A ROC curve was used to evaluate the performance of plasma IL-17 in detecting RA. Given 100% specificity, the highest sensitivity of plasma IL-17A was 61.7% at a cut-off value of 18.25 pg/ml; p < 10E-21, CI = [0.849–0.939]. Analytic results showed that the IgM-rheumatoid factor and anti-CCP antibodies were significantly less frequent in patients with the IL-17RC*A/A genotype than those carrying *G/G and *G/A genotypes; p = 0.013 and p = 0.015, respectively. Otherwise, IL-17 plasma levels’ analysis showed a significant association with the activity of RA (DAS28≥5.1 = 74.71 pg/ml vs. DAS28<5.1 = 11.96 pg/ml), p<10E-6.

Conclusion

IL-17A*rs2275913 (G/A) and IL-17RC*rs708567 (G/A) polymorphisms did not seem to influence RA susceptibility in Tunisian population. This result agrees with those reported previously. Plasma IL-17A level seems to be predictive of severe RA occurrence.

The role of IL-23 receptor signaling in inflammation-mediated erosive autoimmune arthritis and bone remodeling

The IL‐23/Th17 axis has been implicated in the development of autoimmune diseases, such as rheumatoid arthritis (RA) and psoriatic arthritis (PsA). RA and PsA are heterogeneous diseases with substantial burden on patients. Increasing evidence suggests that the IL‐23 signaling pathway may be involved in the development of autoimmunity and erosive joint damage. IL‐23 can act either directly or indirectly on bone forming osteoblasts as well as on bone resorbing osteoclasts. As IL‐23 regulates the activity of cells of the bone, it is conceivable that in addition to inflammation‐mediated joint erosion, IL‐23 may play a role in physiological bone remodeling. In this review, we focus on the role of IL‐23 in autoimmune arthritis in patients and murine models, and provide an overview of IL‐23 producing and responding cells in autoimmune arthritic joints. In addition, we discuss the role of IL‐23 on bone forming osteoblasts and bone resorbing osteoclasts regarding inflammation‐mediated joint damage and bone remodeling. At last, we briefly discuss the clinical implications of targeting this pathway for joint damage and systemic bone loss in autoimmune arthritis.