The interleukin 23 receptor gene does not confer risk to systemic sclerosis and is not associated with systemic sclerosis disease phenotype

Determination of IL-23 receptor expression and gene polymorphism (rs1884444) in Iranian patients with ankylosing spondylitis

BACKGROUND

Through investigating genetic variations, it has been demonstrated that single nucleotide polymorphisms (SNPs) in the IL-23 receptor (IL23R) gene have a critical role in the pathophysiology of ankylosing spondylitis (AS). Here, we investigated whether the IL23R variant (rs1884444) is associated with AS in the Iranian population.

METHODS AND MATERIAL

In this research, we analyzed rs1884444 in a group of 425 patients with AS and 400 matched controls. For DNA extraction, the phenol/chloroform technique was utilized. Peripheral blood mononuclear cells (PBMCs) were obtained from the whole blood of 39 patients and 43 healthy controls and total RNA was extracted. Genotyping was performed by amplification-refractory mutation system (ARMS)-PCR method. Afterward, the expression level of IL23R was analyzed by the real-time quantitative (Q)-PCR method.

RESULTS

We observed no significant association between the distribution of alleles and genotypes of rs1884444 and susceptibility to AS. In addition, the expression level of IL23R did not differ between PBMCs from AS patients compared to the control group (P = 0.167). Furthermore, the relative expression level of IL23R was positively correlated with the BASDAI (P < 0.01) and BASFI (P < 0.05) scores of the patients.

CONCLUSION

It appears that IL23R polymorphism (rs1884444) and the level of gene expression might not contribute to the susceptibility to AS in the Iranian population. The correlation of IL23R expression with the level of BASDAI and BASFI scores in patients may be due to the role of the IL-23/IL-23R signaling cascade in inflammation and exert a critical role in the development of AS.

Cellular and Molecular Diversity in Scleroderma

With the increasing armamentarium of high-throughput tools available at manageable cost, it is attractive and informative to determine the molecular underpinnings of patient heterogeneity in systemic sclerosis (SSc). Given the highly variable clinical outcomes of patients labelled with the same diagnosis, unravelling the cellular and molecular basis of disease heterogeneity will be crucial to predicting disease risk, stratifying management and ultimately informing a patient-centered precision medicine approach. Herein, we summarise the findings of the past several years in the fields of genomics, transcriptomics, and proteomics that contribute to unraveling the cellular and molecular heterogeneity of SSc. Expansion of these findings and their routine integration with quantitative analysis of histopathology and imaging studies into clinical care promise to inform a scientifically driven patient-centred personalized medicine approach to SSc in the near future.

Classical Disease-Specific Autoantibodies in Systemic Sclerosis: Clinical Features, Gene Susceptibility, and Disease Stratification

Systemic sclerosis (SSc) is an autoimmune disease characterized by abnormalities in microcirculation, extracellular matrix accumulation, and immune activation. Autoantibodies are markers of immune abnormalities and provide diagnostic and predictive value in SSc. Anti-topoisomerase antibodies (ATAs), anticentromere antibodies (ACAs), and anti-RNA polymerase antibodies (ARAs) are the three classical specific antibodies with the highest availability and stability. In this review, we provide an overview of the recent progress in SSc research with respect to ATAs, ACAs, and ARAs, focusing on their application in distinguishing clinical phenotypes, such as malignancy and organ involvement, identifying genetic background in human leukocyte antigen (HLA) or non-HLA alleles, and their potential roles in disease pathogenesis based on the effects of antigen-antibody binding. We finally summarized the novel analysis using ATAs, ACAs, and ARAs on more detailed disease clusters. Considering these advantages, this review emphasizes that classical SSc-specific autoantibodies are still practical and have the potential for patient and risk stratification with applications in precise medicine for SSc.

The profiles of miRNAs and lncRNAs in peripheral blood neutrophils exosomes of diffuse cutaneous systemic sclerosis

BACKGROUND

Diffuse cutaneous systemic sclerosis (dSSc) is a systemic autoimmune disease with skin fibrosis. Neutrophils display important roles in autoimmunity, inflammation, vasculopathy and fibrosis. Exosomes (EXOs) are cell-derived vesicles contained various noncoding RNAs, mRNA and proteins with biological roles.

OBJECTIVE

To investigate the roles of miRNAs and lncRNAs from dSSc neutrophils EXOs.

METHODS

EXOs were isolated from cultured neutrophils supernatants and identified by transmission electron microscopy. Global expression of miRNAs and lncRNAs in neutrophils EXOs were sequenced by Illumina HiSeq 3000 and bioinformatic analyses were performed by R/Bioconductor. Genes were validated by real-time quantitative PCR.

RESULTS

In profiles of neutrophils EXOs, we identified 22 dysregulated miRNAs and 281 dysregulated lncRNAs. Predicted target genes of them were enriched in GO, KEGG and Reactome pathways, Wnt, AMPK, IL-23 and NOTCH signaling pathways were selected for further analysis. Widely interactions among them were also found. Human dermal microvascular endothelial cells and human primary skin fibroblasts were stimulated with dSSc neutrophils EXOs, these fibrosis related genes were detected and some changes were found, such as ENST00000533886.1-hsa-miR-1268a-CAMK2G in Wnt and IL-23 signaling pathways, ENST00000610091.1-hsa-miR-299-3p, 512-3p-CPT1A in IL-23 and AMPK signaling pathways, NR_001564.2, ENST00000520562.1, ENST00000596567.1-hsa-miR-299-3p, 512-3p -TFDP2 in IL-23, AMPK and NOTCH signaling pathways.

CONCLUSIONS

The profiles of miRNAs and lncRNAs of neutrophils EXOs provided novel clues for dSSc pathogenesis. We identified several gene pairs in the Wnt, AMPK, IL-23 and NOTCH signaling pathways, which could be potential biomarkers and therapeutic targets in dSSc.

Interleukin-23 receptor gene polymorphisms in Iranian patients with juvenile systemic lupus erythematosus

INTRODUCTION AND OBJECTIVES

Considering the possible roles of interleukin-23 receptor (IL-23R) gene in the pathogenesis of juvenile systemic lupus erythematosus (JSLE), the objective of this study was to elucidate whether polymorphisms of the IL23R are associated with susceptibility to JSLE in an Iranian population.

MATERIALS AND METHODS

A case-control study on 62 patients with JSLE and 78 healthy controls was performed to investigate the associations of four single nucleotide polymorphisms (SNPs) in IL-23R gene, namely, rs7517847, rs10489629, rs11209026, and rs1343151, with susceptibility to JSLE, using real-time polymerase chain reaction Taqman genotyping technique.

RESULTS

Analysis of allele and genotype frequency of four selected SNPs revealed statistically significant positive association between homozygous variant of rs7517847 (TT) (P, 0.02) and T allele at the same position (P, 0.01) with JSLE vulnerability. There was no significant association between other evaluated SNPs and JSLE susceptibility.

CONCLUSION

These findings suggest that particular IL-23R gene variants could affect individual susceptibility to JSLE.

Is there a role for IL-17 in the pathogenesis of systemic sclerosis?

In systemic sclerosis (SSc) immuno-inflammatory events are central to disease development. Amongst other mediators of inflammation, interleukin 17 (IL-17) and Th17 cells have been reported to be increased in the peripheral blood and target organs including involved skin in SSc. They participate and amplify inflammatory responses by inducing the production of cytokines such as IL-6, chemokines such as CCL2 and CXCL8 (IL-8), matrix metalloproteinases-1, -2, -9 and the expression of adhesion molecules in stromal cells including fibroblasts and endothelial cells. In this respect, IL-17 and Th17 cells behave paradigmatically as documented in other autoimmune pathological conditions or infectious diseases. In experimental animal models of skin and lung fibrosis, IL-17 indirectly enhances the fibrotic process by favoring further inflammation by recruiting inflammatory cells, by activating and/or stimulating the production of TGF-β and other pro-fibrotic mediators, by inhibiting autophagy. Whether the findings generated in animal models of fibrosis can be translated to human SSc is unproven. Furthermore, it is controversial whether IL-17 directly promotes the transdifferentiation of human fibroblasts into myofibroblasts and enhances collagen production, with most of the available evidence against this possibility. The reductionist approach in which fibroblast in monolayers are cultured in plastic dishes under the influence of IL-17 limits the relevance of these findings. Further in vitro/ex vivo models with human tissues are being developed to investigate the real effect of IL-17 on extracellular matrix deposition, since agents blocking IL-17 are available for the clinic and it will be important to know whether their use in SSc would be beneficial or detrimental.

IL-17 and related cytokines involved in systemic sclerosis: Perspectives

Systemic sclerosis (SSc) is a multisystemic, complex, and rare disease of connective tissue, with high morbidity and mortality, and without specific treatment. The disease is characterized by three main principles: vascular disease, autoantibody production and inflammation, and fibrosis. Since it is well defined that SSc is characterized by elevated production of TGF-β, IL-6, and IL-1, all of them cytokines related to Th17 differentiation, the hypothesis is that this disease may be strongly related to a polarization of the immune response towards the Th17 pathway. Considering the importance of a better understanding of the pathophysiology of Th17 pathway in SSc, this article aims to propose an update for a better understanding of current knowledge on main cytokines secreted by the Th17 cells (IL-17 A, IL-21, and IL-22) and the future prospects in the current disease.

Genetics of systemic sclerosis: recent advances

Purpose of review

Large-scale and follow-up genetic association studies in systemic sclerosis (SSc) have implicated over 40 regions in disease risk, 15 of which with robust associations. Nevertheless, the causal variants and the functional mechanisms underlying the genetic associations remain elusive, and the reasons for the higher disease burden in African Americans unknown. Incorporating tools from diverse fields is beginning to unveil the role of genetic diversity and regulatory variation in SSc susceptibility. This review will summarize recent advances in SSc genetics, including autoimmune disease overlap, evidence of natural selection, and current progress towards the dissection of the functional role of associated risk variants.

Recent findings

In the past year, multiple large-scale studies reported novel strong and suggestive SSc associations. These results, coupled with the regions shared with other autoimmune diseases, emphasize the role of dysregulation of immune pathways as a key causative factor in SSc pathogenesis. Strong evidence implicates natural selection as a mechanism contributing to the maintenance of some of these SSc alleles in the population. Studies integrating genomic, transcriptomic, and epigenomic datasets in specific cell types to identify causal autoimmune disease variants are emerging.

Summary

The identification and comprehensive understanding of the factors and mechanisms contributing to SSc will contribute to improved diagnosis and disease management.

Genetic Susceptibility to Interstitial Lung Disease Associated with Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease that is characterized by tissue fibrosis, microvasculopathy, and autoimmunity. Interstitial lung disease (ILD) is a common complication of SSc and is one of the frequent causes of mortality in SSc. Although the exact etiology of SSc remains unknown, clinical and experimental investigations have suggested that genetic and environmental factors are relevant to the pathogenesis of SSc and SSc-ILD. More than 30 genes have been identified as susceptibility loci for SSc, most of which are involved in immune regulation and inflammation. It is thought that the key pathogenesis of SSc-ILD is caused by the release of profibrotic mediators such as transforming growth factor β1 and connective tissue growth factor from lung cells induced by a persistent damage. This review presents the genetic susceptibility to SSc-ILD, including human leukocyte antigen and non-human leukocyte antigen genes, especially focusing on connective tissue growth factor.

Interleukin-35 is upregulated in systemic sclerosis and its serum levels are associated with early disease

OBJECTIVES

IL-35 is a member of the IL-12 family consisting of p35/IL-12a and EBI3/IL-27b subunits. IL-35 exerts immunomodulatory activities in experimental and human autoimmune inflammatory conditions. Our aim was to assess IL-35 expression in the skin and circulation of SSc patients and to characterize its potential association with SSc-related features.

METHODS

Expression of IL-35 in skin and dermal fibroblasts was quantified by quantitative PCR, immunohistochemistry and immunofluorescence. Serum levels of IL-35 (by ELISA), CRP (by turbidimetry), ANA (by immunofluorescence) and autoantibodies of the ENA complex (by immunoblot) were measured in 40 SSc patients. Serum IL-35 was determined in 40 age- and sex-matched healthy controls.

RESULTS

IL-35 expression was increased in SSc skin and dermal fibroblasts in a TGF-β-dependent manner. IL-35 induced an activated phenotype in resting fibroblasts and enhanced the release of collagen. IL-35 serum levels were increased in patients with SSc compared with healthy controls [median 83.9 (interquartile range 45.1-146.1) vs 36.2 (interquartile range 17.2-49.4) pg/ml, P < 0.0001]. Serum IL-35 was negatively correlated with disease duration (r = -0.4339, P = 0.0052). In line with this finding, serum IL-35 was increased in patients with an early SSc pattern on capillaroscopy assessment compared with those with active and late SSc patterns.

CONCLUSION

The present study demonstrates overexpression of IL-35 in SSc skin, dermal fibroblasts and serum. TGF-β induces IL-35, which in turn activates resting fibroblasts and enhances the release of collagen, thereby contributing to aberrant TGF-β signalling in SSc. Increased serum IL-35 is associated with early, inflammatory stages of SSc.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

Systemic Sclerosis is a Complex Disease Associated Mainly with Immune Regulatory and Inflammatory Genes

Systemic sclerosis (SSc) is a fibrotic and autoimmune disease characterized clinically by skin and internal organ fibrosis and vascular damage, and serologically by the presence of circulating autoantibodies. Although etiopathogenesis is not yet well understood, the results of numerous genetic association studies support genetic contributions as an important factor to SSc. In this paper, the major genes of SSc are reviewed. The most recent genome-wide association studies (GWAS) are taken into account along with robust candidate gene studies. The literature search was performed on genetic association studies of SSc in PubMed between January 2000 and March 2014 while eligible studies generally had over 600 total participants with replication. A few genetic association studies with related functional changes in SSc patients were also included. A total of forty seven genes or specific genetic regions were reported to be associated with SSc, although some are controversial. These genes include HLA genes, STAT4, CD247, TBX21, PTPN22, TNFSF4, IL23R, IL2RA, IL-21, SCHIP1/IL12A, CD226, BANK1, C8orf13-BLK, PLD4, TLR-2, NLRP1, ATG5, IRF5, IRF8, TNFAIP3, IRAK1, NFKB1, TNIP1, FAS, MIF, HGF, OPN, IL-6, CXCL8, CCR6, CTGF, ITGAM, CAV1, MECP2, SOX5, JAZF1, DNASEIL3, XRCC1, XRCC4, PXK, CSK, GRB10, NOTCH4, RHOB, KIAA0319, PSD3 and PSOR1C1. These genes encode proteins mainly involved in immune regulation and inflammation, and some of them function in transcription, kinase activity, DNA cleavage and repair. The discovery of various SSc-associated genes is important in understanding the genetics of SSc and potential pathogenesis that contribute to the development of this disease.

Lack of association between IL-23R gene polymorphisms and systemic lupus erythematosus in a Chinese population

OBJECTIVE

The aim to this study was to investigate the association between the single-nucleotide polymorphisms (SNPs) of interleukin (IL)-23 receptor gene and systemic lupus erythematosus (SLE) in a Chinese population.

METHODS

A case-control study was performed to investigate the associations of SNPs in IL-23R gene (rs10889677 and rs1884444) with susceptibility to SLE in 521 Chinese SLE patients and 527 normal controls. The chi-square test and unconditional Logistic regression were used to analysis by SPSS 10.1 software.

RESULTS

No significant differences were detected for the distribution of allele and genotype frequencies of these two SNPs between patients and controls as well as SLE patients with nephritis (LN) and those without nephritis.

CONCLUSION

The findings suggest that the polymorphisms of IL-23R gene might not contribute to the susceptibility of SLE in the Chinese population.

IL-17: a new actor in IFN-driven systemic autoimmune diseases

Systemic autoimmune diseases such as systemic lupus erythematosus are type I IFN-driven diseases with exaggerated B-cell responses and autoantibody production. Th17 cells, a T-helper-cell subset with high inflammatory capacity, was initially discovered and characterized in the context of experimental autoimmune encephalomyelitis - an animal model of multiple sclerosis. There is now emerging evidence that Th17 cells, and more generally IL-17 and IL-17-producing cells, may play a role in the pathogenesis of type I IFN-driven systemic autoimmune diseases such as lupus. Here, we review the different studies suggesting a role for IL-17 and IL-17-producing cells in systemic autoimmune diseases, both in humans and in animal models, and we consider the possible mechanisms by which these cells may contribute to disease. We also discuss the hypothesis that type I IFN and IL-17 act in concert to sustain and amplify autoimmune and inflammatory responses, making them a dangerous combination involved in the pathogenesis of systemic autoimmune diseases.

Deciphering the genetic background of systemic sclerosis

Systemic sclerosis (SSc) is a severe autoimmune connective tissue disease. Over the years, evidence for a genetic background of SSc susceptibility has clearly accumulated. This article aims to provide an extensive overview of genetics in SSc research. We discuss indicators for a genetic component present in SSc, family studies, chromosomal aberrances, the involvement of the HLA region and multiple candidate genes and, finally, genome-wide association studies.

A GWAS follow-up study reveals the association of the IL12RB2 gene with systemic sclerosis in Caucasian populations

A single-nucleotide polymorphism (SNP) at the IL12RB2 locus showed a suggestive association signal in a previously published genome-wide association study (GWAS) in systemic sclerosis (SSc). Aiming to reveal the possible implication of the IL12RB2 gene in SSc, we conducted a follow-up study of this locus in different Caucasian cohorts. We analyzed 10 GWAS-genotyped SNPs in the IL12RB2 region (2309 SSc patients and 5161 controls). We then selected three SNPs (rs3790567, rs3790566 and rs924080) based on their significance level in the GWAS, for follow-up in an independent European cohort comprising 3344 SSc and 3848 controls. The most-associated SNP (rs3790567) was further tested in an independent cohort comprising 597 SSc patients and 1139 controls from the USA. After conditional logistic regression analysis of the GWAS data, we selected rs3790567 [P(MH)= 1.92 × 10(-5) odds ratio (OR) = 1.19] as the genetic variant with the firmest independent association observed in the analyzed GWAS peak of association. After the first follow-up phase, only the association of rs3790567 was consistent (P(MH)= 4.84 × 10(-3) OR = 1.12). The second follow-up phase confirmed this finding (P(χ2) = 2.82 × 10(-4) OR = 1.34). After performing overall pooled-analysis of all the cohorts included in the present study, the association found for the rs3790567 SNP in the IL12RB2 gene region reached GWAS-level significant association (P(MH)= 2.82 × 10(-9) OR = 1.17). Our data clearly support the IL12RB2 genetic association with SSc, and suggest a relevant role of the interleukin 12 signaling pathway in SSc pathogenesis.

Alteration of Th17 and Treg cell subpopulations co-exist in patients affected with systemic sclerosis

Aim of the study has been to understand the relationship between TH17 and Treg cell subsets in patients affected with systemic sclerosis (SSc). Phenotypes and functions of Th17 and Treg cell subsets were analyzed in a series of 36 SSc patients. Th17 cell concentration in the peripheral blood was found to be increased in SSc patients with respect to healthy controls independently from type or stage of disease. After PBMC stimulation with a polyclonal stimulus or Candida albicans antigens the frequency of Th17 T cell clones was significantly higher in SSc patients with respect to controls suggesting the skewing of immune response in SSc patients toward Th17 cell generation/expansion. Concerning the Treg compartment, both CD4+CD25+ and CD8+CD28- Treg subsets showed quantitative and qualitative alteration in the peripheral blood of SSc patients. Collectively, these data highlight the existence of an imbalanced ratio between Th17 and Treg cell subsets in SSc patients.

[Cytokines and T cell differentiation in systemic sclerosis]

The physiopathology of systemic sclerosis remains unclear within a complex interaction between vasculopathy, perivascular inflammatory infiltrate, extensive tissue fibrosis and auto-immune manifestations. Chronology between vascular disease and adjacent inflammatory cell infiltration is still not yet clarified. There is growing evidence that T cell activation and its cytokine expression play a key role in vascular impairment occurrence and collagen dysregulation. Nevertheless, cytokine descriptions are mainly limited to blood and tissue measurement and the T cells differentiation analysis restricted to the Th1/Th2 balance. The purpose of this review is to establish an exhaustive cartography of cytokines involved in T cell differentiation, regarding the recent advance in T lymphocyte differentiation, including Th9, Th17, Th22 and regulatory T cells (Treg) pathways. This review will focus on Th17, Th22 and Treg differentiation, corresponding to the equilibrium between inflammation and tolerance. Finally, regarding published results in systemic sclerosis, T cells participation appears to be more a Th1/Th2 co-expression than an exclusive Th1 or Th2 polarization. Also, a possible Th22/Treg imbalance is suggested, leading to a Th22 overexpression and likely to tissue inflammation genesis.

Association of interleukin 23 receptor polymorphisms with anti-topoisomerase-I positivity and pulmonary hypertension in systemic sclerosis

OBJECTIVE

IL23R has been identified as a susceptibility gene for development of multiple autoimmune diseases. We investigated the possible association of IL23R with systemic sclerosis (SSc), an autoimmune disease that leads to the development of cutaneous and visceral fibrosis.

METHODS

We tested 9 single-nucleotide polymorphisms (SNP) in IL23R for association with SSc in a cohort of 1402 SSc cases and 1038 controls. IL23R SNP tested were previously identified as SNP showing associations with inflammatory bowel disease.

RESULTS

Case-control comparisons revealed no statistically significant differences between patients and healthy controls with any of the IL23R polymorphisms. Analyses of subsets of SSc patients showed that rs11209026 (Arg381Gln variant) was associated with anti-topoisomerase I antibody (ATA)-positive SSc (p = 0.001)) and rs11465804 SNP was associated with diffuse and ATA-positive SSc (p = 0.0001, p = 0.0026, respectively). These associations remained significant after accounting for multiple comparisons using the false discovery rate method. Wild-type genotype at both rs11209026 and rs11465804 showed significant protection against the presence of pulmonary hypertension (PHT). (p = 3x10(-5), p = 1x10(-5), respectively).

CONCLUSION

Polymorphisms in IL23R are associated with susceptibility to ATA-positive SSc and protective against development of PHT in patients with SSc.

Interleukin-23 receptor gene variants in Hungarian systemic lupus erythematosus patients

OBJECTIVE

We investigated the association between systemic lupus erythematosus (SLE) and polymorphisms of interleukin-23 receptor (IL23R) gene, which was recently found to be associated with autoimmune diseases, including Crohn's disease, rheumatoid arthritis, psoriasis and ankylosing spondylitis.

SUBJECTS

We analysed 383 SLE patients and 253 controls for rs11805303, rs10889677, rs1004819, rs2201841, rs11209032, 11209026, rs10489629, rs7517847 and rs7530511 variants.

METHODS

The analysis was carried out using PCR-RFLP methods. Logistic regression analysis was used to compare the genotype distributions of the polymorphisms and haplotypes between the SLE patients and healthy controls.

RESULTS

We observed no significant difference of the examined variants between the patient and control groups.

CONCLUSIONS

Our results suggest that neither single nucleotide variants nor haplotypes of IL23R indicate susceptibility to developing SLE in the Hungarian population.

IL23R in the Swedish, Finnish, Hungarian and Italian populations: association with IBD and psoriasis, and linkage to celiac disease

Background

Association of the interleukin-23 receptor (IL23R) with inflammatory bowel disease (IBD) has been confirmed in several populations. IL23R also associates with psoriasis, suggesting that the gene may be an important candidate for many chronic inflammatory diseases.

Methods

We studied association of single-nucleotide variants in IL23R with IBD in Swedish patients, in both Crohn's disease (CD) and ulcerative colitis (UC) subsets. The same genetic variants were also studied in Finnish patients with psoriasis or celiac disease, and in Hungarian and Italian patients with celiac disease.

Results

Association of IL23R with IBD was replicated in our Swedish patients, and linkage and association of the IL23R region with psoriasis was found in the Finnish population. The IL23R region was also linked to celiac disease in Finnish families, but no association of IL23R variants with celiac disease was found in the Finnish, Hungarian or Italian samples.

Conclusion

Our study is the first to demonstrate association of IL23R with CD and UC in Swedish patients with IBD. It is also the first study to report linkage and association of the IL23R region with psoriasis in the Finnish population. Importantly, this is the first report of linkage of the IL23R region to celiac disease, a chronic inflammatory condition in which IL23R has not been previously implicated.