IL23R gene confers susceptibility to ankylosing spondylitis concomitant with uveitis in a Han Chinese population

Sacroiliitis in inflammatory bowel disease

PURPOSE OF REVIEW

This review summarizes the recent evidence regarding the epidemiology of inflammatory bowel disease (IBD) associated sacroiliitis, including the prevalence, pathogenesis, role of imaging, and therapeutic challenges.

RECENT FINDINGS

Sacroiliitis is an underappreciated musculoskeletal manifestation of IBD, a chronic inflammatory condition of the gut affecting the younger population. Untreated sacroiliitis can lead to joint destruction and chronic pain, further adding to morbidity in IBD patients. Recent publications suggest sacroiliitis can be detected on abdominal imaging obtained in IBD patients to study bowel disease, but only a small fraction of these patients were seen by rheumatologists. Early detection of IBD-associated sacroiliitis could be achieved by utilization of clinical screening tools in IBD clinics, careful examination of existing computed tomography and MRI studies, and timely referral to rheumatologist for further evaluation and treatment. Current treatment approaches for IBD and sacroiliitis include several targeted biologic therapies, but IBD-associated sacroiliitis has limited options, as these therapies may not overlap in both conditions.

SUMMARY

With the advances in imaging, sacroiliitis is an increasingly recognized comorbidity in IBD patients. Future studies focusing on this unique patient population will expand our understanding of complex pathophysiology of IBD-associated sacroiliitis and lead to identification of novel targeted therapies for this condition.

Probing the binding of interleukin-23 to individual receptor components and the IL-23 heteromeric receptor complex in living cells using NanoBRET

Interleukin-23 (IL-23) is a pro-inflammatory cytokine involved in the host defense against pathogens but is also implicated in the development of several autoimmune disorders. The IL-23 receptor has become a key target for drug discovery, but the exact mechanism of the receptor ligand interaction remains poorly understood. In this study the affinities of IL-23 for its individual receptor components (IL23R and IL12Rβ1) and the heteromeric complex formed between them have been measured in living cells using NanoLuciferase-tagged full-length proteins. Here, we demonstrate that TAMRA-tagged IL-23 has a greater than 7-fold higher affinity for IL12Rβ1 than IL23R. However, in the presence of both receptor subunits, IL-23 affinity is increased more than three orders of magnitude to 27 pM. Furthermore, we show that IL-23 induces a potent change in the position of the N-terminal domains of the two receptor subunits, consistent with a conformational change in the heteromeric receptor structure.

Association of genetic polymorphisms in IL-23R and IL-17A with the susceptibility to IgA nephropathy in a Chinese Han population

IgA Nephropathy (IgAN) is one of the most common causes of chronic kidney damage worldwide. Identifying new genetic factors associated with IgAN risk is of invaluable importance. To explore the association between polymorphisms of IL-23R and IL-17A and the susceptibility of IgAN, 164 IgAN patients and 192 healthy controls were genotyped for five SNPs in a Chinese Han population. A comparative analysis between genotype distributions, clinical indexes and pathological grades in the IgAN patients was also performed. The GG genotype and a G allele of rs7517847 were associated with a decreased IgAN risk (OR: 0.545; 95% CI: 0.299-0.993; p = 0.046; OR: 0.730; 95% CI: 0.541-0.984; p = 0.039) compared to the TT genotype and T allele respectively. Furthermore, the AA genotype of rs2275913 appeared to reduce the IgAN risk (OR: 0.405; 95% CI: 0.209-0.786; p = 0.007) compared to the GG genotype. Consistently, individuals harboring an AA genotype had a lower IgAN risk (OR: 0.380; 95% CI: 0.211-0.686; p = 0.001) under the recessive model. Our study demonstrated for the first time the significant associations of rs7517847 in IL-23R and rs2275913 in IL-17A with the risk of IgAN in Chinese Han.

IFNA1 and IFNA13 Genes Confer Genetic Predisposition to Ankylosing Spondylitis-Associated Uveitis in a Chinese Population

OBJECTIVES

Uveitis is considered the most frequent extra-articular manifestation of Ankylosing Spondylitis (AS). Genetic factors play an important role in the pathogenesis of AS with uveitis. In this study, we investigated susceptibility genes of AS concomitant with uveitis.

METHODS

First, 9p21-24 was selected as the region of susceptibility genes. Second, several candidate genes were selected from this region by bioinformatics analysis. Thirdly, a two-stage case control study was used to verify these candidate genes. The first stage included 50 AS with uveitis, 50 AS without uveitis, and 145 healthy controls. The qPCR+direct sequencing and cloning sequencing were used to identify SNPs in this stage. The second stage included 245 AS with uveitis, 360 AS without uveitis, and 530 healthy controls.

RESULTS

IFNA1, IFNB1, IFNA8, and IFNA13 were selected as candidate genes. In the first stage, it was found that the frequency of IFNA1 rs28383797 (G allele) and IFNA13 rs653778 (T allele) in AS with uveitis was higher than that in AS without uveitis and healthy controls. In the second stage, more samples were used to verify the two SNPs. After comprehensive data analysis in the two stages, the frequency of rs28383797 G allele and rs653778 T allele in AS with uveitis was significantly higher than that in AS without uveitis (P = 1.9 × 10^-7, OR = 2.161, 95%CI = 1.609-2.902 and P = 1.5 × 10^-9, OR = 2.028, 95%CI = 1.610-2.554) and healthy controls.

CONCLUSIONS

Rs653778 (T allele) of IFNA13 and rs28383797 (G allele) of IFNA1 were associated with AS concomitant uveitis, and may act as the susceptibility genes of AS with uveitis in the Chinese population.

Associations between interleukin-23R polymorphisms and ankylosing spondylitis susceptibility: an updated meta-analysis

OBJECTIVE

The aim of this study was to determine whether interleukin-23R (IL-23R) polymorphisms are associated with susceptibility to ankylosing spondylitis (AS).

METHODS

Meta-analyses were conducted to determine the associations between IL-23R polymorphisms and AS susceptibility in Europeans, Asians, and all subjects combined.

RESULTS

A total of 17 studies (21 separate comparisons) were included in this meta-analysis. The meta-analysis revealed a significant association between AS and the two alleles of the rs11209032 polymorphism in all study subjects (odds ratio [OR] = 1.160, 95% confidence interval [CI] = 1.091-1.204, P < 0.001). Stratification by ethnicity identified a significant association between this polymorphism and AS in Europeans (OR = 1.234, 95% CI = 1.159-1.313, P < 0.001), but not in Asians (OR = 1.003, 95% CI = 0.920-1.219, P = 0.942). Meta-analyses of the rs1004819, rs10489629, rs1343151, rs1495965, rs7517847, and rs11465804 polymorphisms showed the same pattern as shown for rs11209032. The meta-analysis also revealed a significant association between the two alleles of the rs2201841 and rs11209026 polymorphisms and the risk of developing AS in Europeans, but not in Asians. Interestingly, the rs10889677 polymorphism was not found to be associated with AS susceptibility in either Europeans or Asians.

CONCLUSIONS

This meta-analysis showed that several IL-23R polymorphisms are associated with the development of AS in Europeans.

The role of IL-17A in axial spondyloarthritis and psoriatic arthritis: recent advances and controversies

Although the pathogenic mechanisms underlying axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA) are not fully elucidated, several lines of evidence suggest that immune responses mediated by interleukin 17A (IL-17A) play a pivotal role in both diseases. This is best highlighted by the significant clinical efficacy shown with inhibitors of IL-17A in treating axSpA and PsA. Nevertheless, a number of knowledge gaps exist regarding the role of IL-17A in the pathophysiology of spondyloarthritis in man, including its cellular origin, its precise role in discrete disease processes such enthesitis, bone erosion, and bone formation, and the reasons for the discrepant responses to IL-17A inhibition observed in certain other spondyloarthritis manifestations. In this review, we focus on the latest data from studies investigating the role of IL-17A in ankylosing spondylitis (AS) and PsA that build on existing and emerging scientific knowledge in the field. Key remaining research questions are also highlighted to guide future research.

Targeting inflammatory pathways in axial spondyloarthritis

The triggers and pathogenesis of axial spondyloarthritis (axSpA) are not yet completely understood. However, therapeutic agents targeting tumor necrosis factor-α and interleukin-17 inflammatory pathways have proven successful in suppressing many of the clinical symptoms and signs of axSpA, giving us an indication of which pathways are responsible for initiating and maintaining the inflammation. The mechanisms that eventuate in syndesmophytes and ankyloses are less clear. This review addresses these two critical pathways of inflammation, discussing their nature and these factors that may activate or enhance the pathways in patients with axSpA. In addition, genetic and other markers important to the inflammatory pathways implicated in axSpA are explored, and prognostic biomarkers are discussed. Treatment options available for the management of axSpA and their associated targets are highlighted.

Association between cytokine gene polymorphisms and ankylosing spondylitis susceptibility: a systematic review and meta-analysis

PURPOSE OF THE STUDY

The aim of this study was to perform a meta-analysis to derive precise estimation of the association of interleukin-23 receptor (IL-23R), IL-1 receptor 2 (IL-1R2), IL-12 beta (IL-12B), IL-10 and tumour necrosis factor (TNF)-α polymorphisms with ankylosing spondylitis (AS) susceptibility.

STUDY DESIGN

A systematic literature search was conducted to identify the relevant studies. Pooled OR with 95% CI was calculated to assess the strength of the association in a fixed or random-effects model.

RESULTS

A total of 13 917 cases and 19 849 controls in 43 eligible studies were included in the meta-analysis. Seventeen single-nucleotide polymorphisms (SNPs) in the abovementioned five cytokine genes were evaluated. The results indicate that the nine SNPs (rs11209026, rs1004819, rs10489629, rs11465804, rs1343151, rs11209032, rs1495965, rs7517847, rs2201841) of IL-23R are associated with AS susceptibility in all study subjects in the allelic model. Moreover, stratification by ethnicity identified a significant association between seven SNPs of IL-23R and AS susceptibility in Europeans and Americans, but not in Asians. In addition, the IL-10-819  C/T and TNF-α-857 C/T polymorphisms also confer susceptibility to AS, especially in Asian population.

CONCLUSION

The results suggested that the genetic susceptibility for AS is associated with the nine SNPs of IL-23R in overall population. In the subgroup analysis, significant associations were shown in European and American population, but not in Asian population. Our results also suggest that IL-10-819  C/T and TNF-α-857 C/T polymorphism might be associated with AS risk, especially in Asian population.

Targeting Interleukin-23 in the Treatment of Noninfectious Uveitis

The interleukin (IL)-23/IL-17 axis plays a central role in the pathogenesis of immune-mediated diseases such as psoriasis, psoriatic arthritis, Crohn's disease, and uveitis. Therefore, targeting the IL-23/IL-17 axis has become the focus of multiple clinical trials for drug development in patients with autoimmune diseases. We briefly describe the biology of the IL-23/IL-17 axis and its relevance to the pathogenesis of experimental and clinical uveitis, and review the monoclonal antibody therapies targeting this pathway. Finally, 2 ongoing phase 2 trials of the anti-IL-23 biologic therapy ustekinumab (STELARA, Janssen Biotech Inc, Horsham, PA) in patients with noninfectious uveitis are introduced.

Cytokines in uveitis

PURPOSE OF REVIEW

Increasing evidence supports Th17 cells as key mediators of ocular inflammatory disease. Cytokines that are important for the development and pathologic function of these cells are potential therapeutic targets in patients with immune mediated uveitis. This review provides an overview of these cytokines including recent insights about their roles in ocular inflammation from laboratory and clinical studies.

RECENT FINDINGS

Interleukin (IL)-6, IL-10, IL-17, IL-22, IL-23 and tumour necrosis factor-alpha (TNFα) are cytokines that have been examined for their functional role in uveitis and their relationship to pathologic Th17 cells. Studies in animal models, particularly in experimental autoimmune uveitis (EAU), have been instrumental in studying the role of these cytokines in disease pathogenesis. More recently, studies on aqueous, vitreous and serum from patients with uveitis using flow cytometry and multiplex ELISA bead-based methodologies have provided insights into the contribution of Th17 cells and the related cytokines in ocular inflammatory diseases. The central role of IL-23 in determining the pathologic Th17 fate has made it an effective therapeutic target in systemic diseases such as psoriasis and thereby an attractive potential target for patients with immune-mediated uveitis.

SUMMARY

Th17 cells, and their related cytokines, are important inflammatory mediators in autoimmune uveitis. Animal and human studies continue to provide new information to direct development of new cytokine-targeted therapies for patients with uveitis.

IL23R gene variants in relation to IL17A levels and clinical phenotype in patients with ankylosing spondylitis

Background

IL23 receptor (IL23R) binding by IL23 is required for the maturation of CD4⁺ cells into Th17 cells and subsequent generation of IL17A and TNF. As IL23R variations contribute to AS susceptibility, we investigated the effect of IL23R variants on cytokine levels and disease measures in an AS cohort.

Methods

This was a cross-sectional study of AS patients (n = 334, 90% B27⁺, age 45 years). IL23R genotyping for three non-synonymous single-nucleotide polymorphisms (rs11209026, protective allele A; rs10489629, protective allele A; and rs11209032, risk allele A) was done by Taqman RT-PCR. IL23, IL17A, TNF and IL6 concentrations were determined by sandwich ELISA. Genotypic associations were analysed with non-parametric methods.

Results

Twenty-two AS patients (6.6%) carried the protective rs11209026 A allele, whereas 206 (61.7%) carried the rs11209032A risk allele (P = 0.03). Two patients homozygous for rs11209026A had late onset, no co-morbidity and undetectable cytokine levels. IL23R genotypes and five common haplotypes were unrelated with age at onset, BASFI or co-morbidity (all P >0.2). There was no overall difference in the concentration of IL17A (184 vs 233 pg/ml, P > 0.2) or IL23 (276 vs 262 pg/ml, P > 0.4) between AS patients and controls, but a global haplotype association (P = 0.01) was observed for IL23 concentrations.

Conclusion

Homozygosity for rs11209026A is rare in AS patients, but may ameliorate the clinical presentation. IL17A and IL23 levels are similar in controls and AS patients. IL23R variants influence IL23 levels but not IL17A levels in AS patients, suggesting that IL23R impacts more on cell types other than Th17 cells.

The association between genetic polymorphisms of the interleukin-23 receptor gene and susceptibility to uveitis: a meta-analysis

Background

Uveitis is an eye inflammatory disease, which is sometimes associated with underlying systemic disease. Interleukin-23 plays an important role in autoimmune disease. The aim of this meta-analysis was to evaluate the association between the interleukin-23 receptor (IL-23R) and susceptibility to uveitis.

Methods

Published literature from PUBMED and EMBASE were retrieved. Seven studies were included in this meta-analysis, covering a total of 1309 cases of uveitis and 2400 controls. Meta-analyses were conducted on the associations between uveitisand rs7517847, rs17375018, and rs11209032 polymorphisms in the IL-23R gene.

Results

There were no significant associations between IL-23R polymorphisms and uveitis with regard to the following alleles: for G allele vs. T allele of rs7517847, OR 1.01, 95% CI 0.92–1.12, P = 0.83; for A allele vs. G allele of rs17375018, OR 0.68, 95% CI 0.47–0.99, P = 0.05; rs11209032 OR 1.12, 95% CI 0.84–1.51, P = 0.43. In contrast, there were significant associations between the AA + AG gene versus GG gene of rs17375018 and the AA gene versus AG + GG gene of rs11209032 polymorphism with uveitis (OR 0.59, 95% CI 0.35–0.99, P = 0.04; OR 1.32, 95% CI 1.10–1.59, P = 0.003).

Conclusions

This meta-analysis suggests that each allele of IL-23R, including rs7519847, rs17375018 and rs11209032 was negatively associated with uveitis. However, homozygote models, including the rs17375018 GG genotype and rs11209032 AA genotype, were significantly associated with uveitis.

Association of ERAP1, IL23R and PTGER4 Polymorphisms with Radiographic Severity of Ankylosing Spondylitis

Background:

Radiographic severity of ankylosing spondylitis (AS) shows such great variance that some patients never develop syndesmophytes throughout the entire disease span, whereas some develop bamboo spine relatively early.

Objective:

To study the association between ERAP1, IL23R and PTGER4 single nucleotide polymorphisms (SNPs) and radiographic severity in AS patients.

Methods:

rs27044 and rs30187 (ERAP1), rs11209032 (IL23R) and rs10440635 (PTGER4) SNPs were genotyped in 235 AS patients fulfilling the modified New York criteria. Patients were classified as mild- and severe-AS according to modified Stoke AS spinal score (mSASSS). Mild-AS is defined as having mSASSS of “0” following at least 10 years of disease duration. Severe-AS is defined as having mSASSS of >20 (patients with mild vertebral changes (i.e. squaring or erosions) were omitted for clear stratification) regardless of disease duration.

Results:

The genotype distributions and allele frequencies of ERAP1 rs27044 and rs30187, IL23R rs11209032 and PTGER4 rs10440635 SNPs were similar in mild- (n=171, mSASSS=0, 55.6% HLA-B27 positive) and severe-AS patients (n=64, mSASSS=48.5±17.8, 73.4% HLA-B27 positive). After adjustment for clinical differences between groups (gender, disease duration, HLA-B27 and smoking status) by logistic regression analysis, none of the alleles in the investigated SNPs were found to be associated with radiographic severity of AS.

Conclusion:

In radiographically well-categorized AS patients, ERAP1 rs27044 and rs30187, IL23R rs11209032 and PTGER4 rs10440635 SNPs are not found to be associated with radiographic severity of AS.

Association of rs11209032 and rs1004819 Polymorphisms in Interleukin-23 Receptor Gene With Ankylosing Spondylitis

Objectives

This study aims to investigate the distribution of human leukocyte antigen B27 (HLA-B27) alleles (+/-) and interleukin-23 receptor (IL-23R) gene rs11209032 and rs1004819 polymorphisms among ankylosing spondylitis (AS) patients in a Turkish cohort.

Patients and methods

The study sample comprised 106 AS patients (89 males, 18 females; mean age 38.9±10 years; range 19 to 65 years) and 82 healthy controls (70 males, 12 females; mean age 32.15±7.07 years; range 19 to 51 years). Distribution of HLA-B27 alleles (+)/(-) in AS patients were observed by reverse hybridization technique. Genotyping of IL-23R rs11209032 and rs1004819 polymorphisms of AS patients and healthy controls were performed by real time polymerase chain reaction.

Results

Of the AS patients, 69 (65.1%) were HLA-B27 positive. Distribution of rs11209032 genotype frequencies in AS group were 31.1% for GG, 50.9% for GA, and 17.9% for AA; while in control group, it was 34.1% for GG, 53.7% for GA, and 12.2% for AA. Distribution of rs1004819 genotype frequencies in AS group were 30.2% for CC, 52.8% for CT, and 17.0% for TT; while in control group, it was 42.7% for CC, 46.3% for CT, and 11.0% for TT. There was no significant difference between AS patients and controls in terms of genotype frequencies of IL-23R gene rs11209032 and rs1004819 polymorphisms.

Conclusion

No association was found between AS and IL23R rs11209032 and rs1004819 polymorphisms in this Turkish AS cohort.

Non-conventional forms of HLA-B27 are expressed in spondyloarthritis joints and gut tissue

Objectives

Human leukocyte antigen (HLA)-B27 (B27) is the strongest genetic factor associated with development of Ankylosing Spondylitis and other spondyloarthropathies (SpA), yet the role it plays in disease pathogenesis remains unclear. We investigated the expression of potentially pathogenic non-conventional heavy chain forms (NC) of B27 in synovial and intestinal tissues obtained from SpA patients. We also determined the presence of NC-B27 in joints, lymphoid and gastrointestinal tissue from B27 transgenic (TG¹) rats with M.tuberculosis-induced SpA.

Methods

Expression of NC-B27 in human SpA joints and gut and in (21-3 × 283-2)F₁ HLA-B27/Huβ2m rat tissue was determined by immunohistochemistry, flow cytometry and confocal microscopy analysis using HC10 and HD6 antibodies.

Results

Both HC10- and HD6-reactive HLA molecules were present in synovial tissue from SpA patients. Both NC-B27 and KIR3DL2, a ligand for NC-B27, were expressed in inflamed terminal ileal tissues in patients with early SpA. Infiltrating cells in inflamed joint tissues isolated from B27 TG¹ rats expressed high levels of NC-B27. NC-B27 were also expressed in joint-resident cells from ankle and tail joints of B27 TG¹ rats prior to clinical arthritis. The expression of NC-B27 on B27 TG¹ rat CD11b/c⁺, CD8α⁺, cells from spleens and LNs increased with animal age and disease progression.

Conclusions

Non-conventional HLA class 1 molecules are expressed on resident and infiltrating cells in both synovial and GI tissues in human SpA. NC-B27 expression in joints and lymphoid tissues from B27 TG¹ rats prior to the onset of arthritis is consistent with the hypothesis that they play a pathogenic role in SpA.

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HLA-B27 predisposes to Ankylosing Spondylitis and related Spondyloarthritis (SpA).

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Non-conventional HLA-B27 free heavy chains (NC-B27) bind innate immune receptors.

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NC HLA class I molecules are expressed in joint and gut tissues in human and rat SpA.

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B27 transgenic rats express NC-B27 prior to arthritis onset.

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These data support a pathogenic role for non-conventional B27 in SpA.

Association between Polymorphism of Interleukin-23 Receptor and Hashimoto's Thyroiditis in Chinese Han Population of Shandong

Objective:

The interleukin-23 receptor (IL-23R) has been shown to be associated with autoimmune diseases in many different populations. This study aimed to investigate the association between IL-23R gene polymorphism and susceptibility to Hashimoto's thyroiditis (HT) in Chinese Han population of Shandong.

Methods:

A case–control cohort study was performed in 145 HT patients from First People's Hospital of Jining between February 2010 to October 2013 and 150 healthy controls. Two single nucleotide polymorphisms located in the promoter region of IL-23R gene (rs17375018 and rs7517847) were examined by polymerase chain reaction-restriction fragment length polymorphism analysis. Hardy-Weinberg equilibrium was performed using the Chi-square test. Genotype frequencies were estimated by direct counting, and allele and genotype frequencies between patients and controls were analyzed by the Chi-square test.

Results:

The rs17375018 GG genotype and the G allele were significantly increased in HT patients compared with healthy controls (P = 0.034 and P = 0.013, respectively). No association was identified between HT patients and healthy controls in rs7517847.

Conclusion:

The study demonstrated that polymorphism of IL-23R gene rs17375018 is highly associated with HT in Chinese Han population of Shandong, suggesting that IL-23R gene polymorphism (rs17375018 G) may play a critical role in susceptibility to HT.

Insights into IL-23 biology: From structure to function

Interleukin (IL-)23 is a central cytokine controlling TH17 development. Overshooting IL-23 signaling contribute to autoimmune diseases. Moreover, GWAS studies have identified several SNPs within the IL-23 receptor, which are associated with autoimmune diseases. IL-23 is a member of the IL-12-type cytokine family and consists of IL-23p19 and p40. Within the IL-12 family, IL-12 and IL-23 share the p40 cytokine subunit and the IL-12Rβ1 as one chain of the receptor complex. For signaling, IL-23 triggers heterodimerization of IL-12Rβ1 and the IL-23R. Subsequently, signal transduction pathways including JAK/STAT, MAPK and PI3K are activated. Most studies have investigated the biological relevance of IL-23 in the development of TH17 cells and autoimmunity, whereas less is known about the molecular context of IL-23 biology. Therefore, we focused on IL-23 receptor complex assembly, signal transduction and functional relevance of IL-23R SNPs in the context of IL-23-inhibitory principles.

Interleukin-23R rs7517847 T/G Polymorphism Contributes to the Risk of Crohn's Disease in Caucasians: A Meta-Analysis

The association between Interleukin-23R gene polymorphism and Crohn's disease (CD) in Caucasians is still controversial. Thus, a meta-analysis was performed to evaluate the correlation between this gene variant and CD risk. We retrieved the available data from EMBASE and PUBMED until May 1, 2014, and evaluated the effect of rs7517847 in Caucasians. The significant associations were confirmed between rs7517847 and CD risk in dominant models (TT/TG versus GG: OR = 1.652, 95% CI 1.277, 2.137), allelic model (T allele versus G allele: OR = 1.327, 95% CI 1.198, 1.469), homozygote comparison (TT versus GG: OR = 1.890, 95% CI 1.465, 2.437), heterozygote comparison (TG versus GG: OR = 1.509, 95% CI 1.161, 1.960), and recessive model (TT versus TG/GG: OR = 1.409, 95% CI 1.279, 1.552). In conclusion, this meta-analysis demonstrates that rs7517847 is associated with the risk of CD in Caucasians. These findings show that IL-23R genes confer susceptibility to CD in the Caucasians.

Association between rs7517847 and rs2201841 polymorphisms in IL-23 receptor gene and risk of ankylosing spondylitis: a meta-analysis

To comprehensively evaluate the association between rs7517847 and rs2201841 polymorphisms in the Interleukin-23 (IL-23) receptor gene and ankylosing spondylitis (AS), a meta-analysis was performed. The Pubmed, Embase, MEDLINE, Cochrane, China National Knowledge Infrastructure (CNKI), VIP, Wanfang and China Biology Medicine disc (CBMdisc) databases were searched to identify eligible studies on rs7517847 and rs2201841 polymorphisms in the IL-23 receptor gene and AS that were published through September 2014. Data of interest were extracted from each study, and the meta-analysis was performed using STATA 12.0. Four studies were eligible for the meta-analysis and included a total patient population of 2,465. With regards to rs7517847, the current study showed that the genotype GG and allele G might play a protective role during AS (OR = 0.76, 95% CI [0.59-0.99]; OR = 0.88, 95% CI [0.78-0.99] for homozygote and allelic models, respectively). However, according to the meta-analysis, there was no statistical association between the genotype or allele of rs2201841 and an individual's susceptibility to AS in all genetic models. In conclusion, it was the IL-23 rs7517847 polymorphism rather than the rs2201841 polymorphism that had a statistical association with AS. Nevertheless, more evidence is needed to confirm this result. Consequently, it is necessary to carry out more high-quality studies to confirm the associations between these two single nucleotide polymorphisms and AS.

Cytokine profiles in axial spondyloarthritis

Objectives

Current studies concentrate on the cytokine network and its role in the pathogenesis of spondyloarthritis (SpA). In this study, we analyzed whether the serum cytokine profile (interleukins: IL-10, IL-11, IL-12, IL-15, IL-17, IL-23 and IL-33) correlates with demographic data, clinical manifestations, disease activity and treatment outcome in a group of patients with axial spondyloarthritis.

Material and methods

Forty-nine patients with an established diagnosis of axial spondyloarthritis (aSpA) and 19 healthy volunteers as controls were enrolled in the study. Clinical evaluation included patient's medical history, 44 joint count, back pain intensity and global disease activity in the preceding week (VAS), the duration of morning stiffness and blood tests. Disease activity was assessed using BASDAI and ASDAS-CRP. Serum concentration of IL-10, IL-11, IL-12, IL-15, IL-17, IL-23 and IL-33 was determined.

Results

In patients with aSpA, elevated serum concentration of IL-10, IL-15, IL-17 and IL-23 was detected. In the aSpA group we detected higher values of serum concentration of IL-23 and IL-33 in the subgroup with anterior uveitis (83.1 ±184.0 pg/ml vs. 14.0 ±17.1 pg/ml, p < 0.0001 and 45.5 ±71.9 pg/ml vs. 18.4 ±14.3 pg/ml, p < 0.0001, respectively). Additionally, in the subgroup with peripheral arthritis, elevation of serum concentration of IL-12 (249.3 ±246.9 pg/ml vs. 99.9 ±105.9 pg/ml, p = 0.0001) was detected. Patients with preradiological SpA had higher serum concentration of IL-17 than patients with established diagnosis of AS (6.37 ±8.50 pg/ml vs. 2.04 ±2.98 pg/ml, p = 0.0295). No differences in serum concentration of analyzed cytokines were found between the subgroup with low to moderate disease activity and the subgroup with high to very high disease activity.

Conclusions

We report that in aSpA patients, compared to controls, elevated serum concentrations of IL-10, IL-15, IL-17 and IL-23 were observed. Some cytokines may predispose to a more severe course of aSpA.

The rs7517847 polymorphism in the IL-23R gene is associated with gout in a Chinese Han male population

OBJECTIVES

Gout is a polygenic auto-inflammatory disease, in which inflammation plays an important role in disease pathogenesis. The cytokine interleukin (IL)-23 promotes inflammation and helps to guide inflammatory cells, while studies have shown that the IL-23R gene is associated with susceptibility to several immune-related diseases. This study aimed to determine whether the IL-23R rs7517847 (G/T) polymorphism is associated with gout in a Chinese Han male population.

METHODS

We recruited 400 patients with gout and 582 gout-free controls. After obtaining blood samples for DNA extraction, genotyping of the rs7517847 polymorphism was performed by fluorescence-based quantitative PCR using TaqMan probes. An association analysis was carried out using the χ(2) test. A genotype-phenotype analysis was also conducted.

RESULTS

Both genotypic and allelic frequencies of rs7517847 differed significantly between gout patients and controls (χ(2) = 6.792, df = 2, P = 0.034 by genotype; χ(2) = 4.202, df = 1, P = 0.04 by allele).

CONCLUSIONS

IL-23R may be associated with gout in a Chinese Han male population, although our findings should be confirmed using larger sample sizes and other independent populations.

Vitamin D and spondyloarthritis

In cross-sectional studies, vitamin D deficiency is frequent in spondyloarthritic patients and associated with increased spondyloarthritis (SpA) activity and structural damage. Experimental studies also show that vitamin D interferes with molecular pathways critically involved in SpA, especially regarding entheseal inflammation and ossification (involving cytokines such as IL-23 and sclerostin). Vitamin D deficiency might also affect the course of the disease through periodontal and gut inflammation, leading to increased functional impairment. Therefore, Vitamin D receptor selective agonists could represent a promising therapeutic pathway in this pathology. Randomised-controlled intervention studies are required in order to further elucidate complex relationships between vitamin D deficiency and SpA.