The IL23R Arg381Gln non-synonymous polymorphism confers susceptibility to ankylosing spondylitis

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.

Diverse selection pressures shaping the genetic architecture of behçet disease susceptibility

Behçet disease (BD) is a polygenic, multifactorial, multisystem inflammatory condition with unknown etiology. Global distribution of BD is geographically structured, highest prevalence observed among East Asian, Middle Eastern, and Mediterranean populations. Although adaptive selection on a few BD susceptibility loci is speculated, a thorough evolutionary analysis on the genetic architecture of BD is lacking. We aimed to understand whether increased BD risk in the human populations with high prevalence is due to past selection on BD associated genes. We performed population genetics analyses with East Asian (high BD prevalence), European (low/very low BD prevalence), and African (very low/no BD prevalence) populations. Comparison of ancestral and derived alleles’ frequencies versus their reported susceptible or protective effect on BD showed both derived and ancestral alleles are associated with increased BD risk. Variants showing higher risk to and more significant association with BD had smaller allele frequency differences, and showed less population differentiation compared to variants that showed smaller risk and less significant association with BD. Results suggest BD alleles are not unique to East Asians but are also found in other world populations at appreciable frequencies, and argue against selection favoring these variants only in populations with high BD prevalence. BD associated gene analyses showed similar evolutionary histories driven by neutral processes for many genes or balancing selection for HLA (Human Leukocyte Antigen) genes in all three populations studied. However, nucleotide diversity in several HLA region genes was much higher in East Asians suggesting selection for high nucleotide and haplotype diversity in East Asians. Recent selective sweep for genes involved in antigen recognition, peptide processing, immune and cellular differentiation regulation was observed only in East Asians. We conclude that the evolutionary processes shaping the genetic diversity in BD risk genes are diverse, and elucidating the underlying specific selection mechanisms is complex. Several of the genes examined in this study are risk factors (such as ERAP1, IL23R, HLA-G) for other inflammatory diseases. Thus, our conclusions are not only limited to BD but may have broader implications for other inflammatory diseases.

No increased risk of alopecia in ankylosing spondylitis patients: A population-based cohort study in Taiwan

AIM

To investigate the association between ankylosing spondylitis (AS) and alopecia.

METHODS

In this cohort study, data from over 1 000 000 patients in the Taiwan Longitudinal Health Insurance Database were extracted. We selected newly diagnosed (outpatient department visit three or more times or admission at least once) patients with AS (ICD-9-CM = 720.0) from 2000 to 2012. For the non-AS comparison group, patients never diagnosed with AS were chosen from 1999 to 2013. In all, 3640 AS patients and 14 560 non-AS controls were selected. Cox proportional hazard model and Kaplan-Meier analysis were used to present the results. The adjusted hazard ratio (HR) in the Cox proportional hazard model was adjusted for age, sex, hypertension, hyperlipidemia, diabetes, atopic dermatitis, and mental disorder.

RESULTS

No increased risk of alopecia in AS patients was shown in the Cox proportional hazard model (crude HR 1.16, P = 0.595; adjusted HR 1.16, P = 0.599). Negative results are found as well in subgroup analysis of different age, sex (age 20-40 y: HR 1.03, P = 0.925; Age ≥40 y: HR 1.49, P = 0.406; Female: HR 1.17, P = 0.759; Male: HR 1.15, P = 0.667), and phenotypes of alopecia (androgenetic alopecia: HR 1.19, 95% confidence interval [CI] 0.58-2.41; alopecia areata: HR 0.98, 95% CI 0.37-2.62). A significant positive correlation is found between atopic dermatitis and alopecia (adjusted HR 8.05, P = 0.039).

CONCLUSION

In this population-based cohort study, we found no association of risk of alopecia and AS.

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.

Reflecting on the immunopathology of arthritis associated with inflammatory bowel disease: what do we know and what should we know?

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is clinically closely associated with arthritis. Three major arthritis clinical subtypes have been described, peripheral arthritis type 1 (PeA1), peripheral arthritis type 2 (PeA2), and axial spondyloarthritis (axSpA). While genetic overlaps between IBD and arthritis have been defined, detailed pathophysiology for these three major subtypes of arthritis in patients with IBD has only recently begun to be established. The genetic and molecular mechanisms distinguishing axial and peripheral arthropathies in patients with UC and CD need to be better described. Understanding the pathophysiology for PeA1, PeA2, and axSpA in the settings of both UC and CD is necessary to provide the fundamental biology underlying the clinical phenotypes in IBD arthritis. This has been attempted for CD-associated spondyloarthritis, differentiating this from both CD and axSpA, while observing unique peripheral blood mononuclear cells linking gut inflammation to joint disease. We should know more about the processes by which immune cells are perturbed in these disorders, how they translocate to joints, how they are activated, what other molecules and mediators are involved, and how gut microbes and microbial products damage joints. Information from such studies are needed to elucidate whether distinctions between IBD-related peripheral and axSpA are clinically meaningful. IBD-related peripheral and axSpA studies are needed to elucidate whether distinctions between peripheral and axSpA are clinically meaningful, to better understand immunopathogenesis, and to develop novel targeted therapies.

Expression Profile of Osteoclasts Following the Stimulation With Interleukin-23 in Mice

Objectives

This study aims to analyze the expression profile of osteoclasts (OCs) following the stimulation with interleukin 23 (IL-23) in mice, which would imply the underlying effects of IL-23 on the function of OCs in inflammatory arthritis.

Materials and methods

Mature OCs were induced from bone marrow mononuclear cells of 5 male mice (age 6 weeks; weighing 18-20 g) in the presence of macrophage-colony stimulating factor (50 ng/mL) and receptor activator of nuclear factor kappa B ligand (30 ng/mL) in vitro. The Agilent SurePrint G3 Mouse GE V2.0 Microarray was used to analyze the gene expression profile of OCs stimulated with IL-23 (30 ng/mL) or vehicle. The four major IL-23-modulated genes were validated by quantitative real-time polymerase chain reaction (qPCR) analysis.

Results

The expression levels of 23 genes were up-regulated and 32 genes were down-regulated by IL-23 stimulation (fold change ≥1.5 and p value <0.05). Among them, there were 37 genes with assigned gene symbols. Gene ontology analysis showed that the IL-23-regulated messenger ribonucleic acids (mRNAs) were related to positive regulation of leukocyte chemotaxis, chemokine-mediated signaling pathway and C-X-C chemokine receptors binding. The pathway analysis showed that the IL-23-regulated mRNAs were related to chemokine signaling pathway and cytokine-cytokine receptor interaction. The significant up-regulation of chemokine (C-X-C motif) ligand 1 and chemokine (C-X-C motif) ligand 2 induced by IL-23 was confirmed by qPCR. In addition, there were 18 long non-coding RNAs that were regulated by IL-23, while their function needs to be confirmed in the future.

Conclusion

Expression levels of genes related to chemotaxis in OCs were up-regulated by IL-23 in mice, which imply that IL-23 may facilitate chemotaxis of OCs in inflammatory arthritis.

A comprehensive overview on the genetics of Behçet's disease

Behçet's disease (BD) is a systemic and inflammatory disease, characterized mainly by recurrent oral and genital ulcers, eye involvement, and skin lesions. Although the exact etiopathogenesis of BD remains unrevealed, a bulk of studies have implicated the genetic contributing factors as critical players in disease predisposition. In countries along the Silk Road, human leukocyte antigen (HLA)-B51 has been reported as the strongest genetically associated factor for BD. Genome-wide association studies, local genetic polymorphism studies, and meta-analysis of combined data from Turkish, Iranian, and Japanese populations have also identified new genetic associations with BD. Among these, other HLA alleles such as HLA-B*15, HLA-B*27, HLA-B*57, and HLA-A*26 have been found as independent risk factors for BD, whereas HLA-B*49 and HLA-A*03 are independent protective alleles for BD. Moreover, other genes have also reached the genome-wide significance level of association with BD susceptibility, including IL10, IL23R-IL12RB2, IL12A, CCR1-CCR3, STAT4, TNFAIP3, ERAP1, KLRC4, and FUT2. Also, several rare nonsynonymous variants in TLR4, IL23R, NOD2, and MEFV genes have been reported to be involved in BD pathogenesis. According to genetic determinants in the loci outside the MHC region that are contributed to the host defense, immunity, and inflammation pathways, it is suggested that immune responses to the pathogen as an important environmental factor and mucosal immunity contribute to BD susceptibility.

From genes polymorphisms to mucosal expression of cytokines: evaluating IL-23/IL-17 axis in adult patients with gastritis

Background and Objective

Chronic inflammation is the typical sign of gastritis that may shift into gastric cancer. IL-17A and IL-17F as a novel inflammatory cytokines subset of CD4+Th play the main role in inflammation. A key cytokine receptor in the inflammatory IL-17/IL-23 axis, the interleukin 23 receptor (IL23R), may be related to gastritis. We evaluated the correspondence between IL-17A G197A, IL-17F A7488G and IL23R+2199 A/C polymorphisms with TGF-β1, IL-6, IL-17, IL-21 and IL-23 mucosal mRNAs expression in uninfected H. Pylori (HP) chronic gastritis patients.

Materials and Methods

Total RNA and genomic DNA were separated from gastric biopsies of 44 patients with gastritis. Subsequently, mucosal mRNAs expression of TGF-β1, IL-6, IL-17, IL-21 and IL-23 were assessed by real-time PCR. To polymorphisms determination of IL-17A G197A, IL-17F A7488G and IL-23R +2199A/C the PCR-RFLP was used in gastric biopsies.

Results

Results point that IL-17A G197A, IL-17F A7488G and IL23R +2199A/C polymorphisms did not influence the mucosal expression of TGF-β1, IL-6, IL-17 and IL-21 (p> 0.05). In an opposite result, we don't find a correspondence between IL-17A G197A, IL-17F A7488G polymorphisms and mucosal expression of IL-23 (p> 0.05). In a contrary, we found a correlation between IL23R +2199A/C polymorphism and mucosal expression of IL-23 in patients with chronic gastritis (p< 0.05).

Conclusion

These findings propose that IL23R +2199A/C polymorphism may change the mucosal expression of IL-23 pattern in patients with gastritis disease in the absence of HP, but to support the conclusion, more research may be required.

Axial Psoriatic Arthritis: A Distinct Clinical Entity in Search of a Definition

Axial involvement in psoriatic arthritis is a well-recognized manifestation with a prevalence between 12.5% and 78%. This huge heterogeneity is due to the different criteria used by authors to define psoriatic arthritis with axial involvement combining clinical features with radiographic evidence of disease. Specific genetic and clinical attributes of axial psoriatic arthritis might differentiate it from axial spondyloarthritis with concurrent skin psoriasis. Few studies address the specific management. The purpose of this review is to acknowledge the current understanding of axial involvement in psoriatic arthritis and highlight the need for a definition to facilitate research and clinical recognition.

IL23 induces IL23R recycling and amplifies innate receptor-induced signalling and cytokines in human macrophages, and the IBD-protective IL23R R381Q variant modulates these outcomes

OBJECTIVE

The interleukin (IL)23 pathway contributes to IBD pathogenesis and is being actively studied as a therapeutic target in patients with IBD. Unexpected outcomes in these therapeutic trials have highlighted the importance of understanding the cell types and mechanisms through which IL23 regulates immune outcomes. How IL23 regulates macrophage outcomes and the consequences of the IL23R R381Q IBD-protective variant on macrophages are not well defined; macrophages are key players in IBD pathogenesis and inflammation.

DESIGN

We analysed protein and RNA expression, signalling and localisation in human monocyte-derived macrophages (MDMs) through western blot, ELISA, real-time PCR, flow cytometry, immunoprecipitation and microscopy.

RESULTS

IL23R was critical for optimal levels of pattern-recognition receptor (PRR)-induced signalling and cytokines in human MDMs. In contrast to the coreceptor IL12Rβ1, IL23 induced dynamic IL23R cell surface regulation and this required clathrin and dynamin-mediated endocytosis and endocytic recycling-dependent pathways; these pathways were essential for IL23R-mediated outcomes. The IBD-protective IL23R R381Q variant showed distinct outcomes. Relative to IL23R R381, HeLa cells expressing IL23R Q381 showed decreased IL23R recycling and reduced assembly of IL23R Q381 with Janus kinase/signal transducer and activator of transcription pathway members. In MDMs from IL23R Q381 carriers, IL23R accumulated in late endosomes and lysosomes on IL23 treatment and cells demonstrated decreased IL23R- and PRR-induced signalling and cytokines relative to IL23R R381 MDMs.

CONCLUSION

Macrophage-mediated inflammatory pathways are key contributors to IBD pathogenesis, and we identify an autocrine/paracrine IL23 requirement in PRR-initiated human macrophage outcomes and in human intestinal myeloid cells, establish that IL23R undergoes ligand-induced recycling, define mechanisms regulating IL23R-induced signalling and determine how the IBD-protective IL23R R381Q variant modulates these processes.

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.

Interleukin-23 receptor (IL-23R) gene polymorphisms and haplotypes associated with the risk of preeclampsia: evidence from cross-sectional and in silico studies

PURPOSE

Pre-eclampsia is a relatively common pregnancy disorder. Serum concentrations of certain pro-inflammatory molecules and cytokines like interleukin-23 may affect the pathogenesis of pre-eclampsia. The interleukin-23 receptor (IL-23R) gene plays an important role in the progression of inflammatory and autoimmune diseases and IL-23 polymorphisms might influence the susceptibility of pre-eclampsia. The aim of the recent study was to establish the association between IL-23R gene polymorphisms and the susceptibility for developing of pre-eclampsia.

METHODS

One hundred and fifty-eight pregnant patients with pre-eclampsia and 153 controls were genotyped using RFLP-PCR and AS-PCR. Also, an in silico analysis was performed to predict possible effects of these variations on IL-23R mRNA and protein structures.

RESULTS

The frequency of the AG genotype of rs11209026 is related to a higher risk of pre-eclampsia. The mutant C and A allele in rs10889677 and rs11209026 SNPs, respectively, are correlated with the risk of pre-eclampsia and they are more frequent in severe late onset PE. We found higher frequency of the haplotype CG in patients with pre-eclampsia in comparison to healthy controls, as well as, the CG haplotype frequency significantly increased the risk of PE in severe, early onset, and late onset sub-groups. The results of computational analysis predicted rs11209026 and rs10889677 SNPs as functional variations, which can influence IL-23R mRNA and protein.

CONCLUSIONS

The results of present study show positive association between polymorphisms in the IL-23R gene and pre-eclampsia. Therefore, the presence of IL-23R rs11209026, rs10889677 polymorphism might be markers for the genetic susceptibility to pre-eclampsia.

Genetically determined high activities of the TNF-alpha, IL23/IL17, and NFkB pathways were associated with increased risk of ankylosing spondylitis

Background

Ankylosing spondylitis (AS) results from the combined effects of susceptibility genes and environmental factors. Polymorphisms in genes regulating inflammation may explain part of the heritability of AS.

Methods

Using a candidate gene approach in this case-control study, 51 mainly functional single nucleotide polymorphisms (SNPs) in genes regulating inflammation were assessed in 709 patients with AS and 795 controls. Data on the patients with AS were obtained from the DANBIO registry where patients from all of Denmark are monitored in routine care during treatment with conventional and biologic disease modifying anti-rheumatic drugs (bDMARDs).

The results were analyzed using logistic regression (adjusted for age and sex).

Results

Nine polymorphisms were associated with risk of AS (p < 0.05). The polymorphisms were in genes regulating a: the TNF-α pathway (TNF -308 G > A (rs1800629), and − 238 G > A (rs361525); TNFRSF1A -609 G > T (rs4149570), and PTPN22 1858 G > A (rs2476601)), b: the IL23/IL17 pathway (IL23R G > A (rs11209026), and IL18–137 G > C (rs187238)), or c: the NFkB pathway (TLR1 743 T > C (rs4833095), TLR4 T > C (rs1554973), and LY96–1625 C > G (rs11465996)).

After Bonferroni correction the homozygous variant genotype of TLR1 743 T > C (rs4833095) (odds ratios (OR): 2.59, 95% confidence interval (CI): 1.48–4.51, p = 0.04), and TNFRSF1A -609 G > T (rs4149570) (OR: 1.79, 95% CI: 1.31–2.41, p = 0.01) were associated with increased risk of AS and the combined homozygous and heterozygous variant genotypes of TNF -308 G > A (rs1800629) (OR: 0.56, 95% CI: 0.44–0.72, p = 0.0002) were associated with reduced risk of AS.

Conclusion

We replicated associations between AS and the polymorphisms in TNF (rs1800629), TNFRSF1A (rs4149570), and IL23R (rs11209026). Furthermore, we identified novel risk loci in TNF (rs361525), IL18 (rs187238), TLR1 (rs4833095), TLR4 (rs1554973), and LY96 (rs11465996) that need validation in independent cohorts. The results suggest that genetically determined high activity of the TNF-α, IL23/IL17, and NFkB pathways increase risk of AS.

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.

Whodunit? The Contribution of Interleukin (IL)-17/IL-22-Producing γδ T Cells, αβ T Cells, and Innate Lymphoid Cells to the Pathogenesis of Spondyloarthritis

γδ T cells, αβ T cells, and innate lymphoid cells (ILCs) are capable of producing interleukin (IL)-17A, IL-17F, and IL-22. Among these three families of lymphocytes, it is emerging that γδ T cells are, at least in rodents, the main source of these key pro-inflammatory cytokines. γδ T cells were implicated in multiple inflammatory and autoimmune diseases, including psoriasis, experimental autoimmune encephalomyelitis and uveitis, colitis, and rheumatoid arthritis. Recent findings pointed toward a central role of γδ T cells in the pathogenesis of spondyloarthritis (SpA), a group of inflammatory rheumatic diseases affecting the axial skeleton. SpA primarily manifests as inflammation and new bone formation at the entheses, which are connecting tendons or ligaments with bone. In SpA patients, joint inflammation is frequently accompanied by extra-articular manifestations, such as inflammatory bowel disease or psoriasis. In humans, genome-wide association studies could link the IL-23/IL-17 cytokine axis to SpA. Accordingly, antibodies targeting IL-23/IL-17 for SpA treatment already showed promising results in clinical studies. However, the contribution of IL-17-producing γδ T cells to SpA pathogenesis is certainly not an open-and-shut case. Indeed, the cell types that are chiefly involved in local inflammation in human SpA still remain largely unclear. Some studies focusing on blood or synovium from SpA patients reported augmented IL-17-producing and IL-23 receptor-expressing γδ T cells, but other cell types might contribute as well. Here, we summarize the current understanding of how γδ T cells, αβ T cells, and ILCs contribute to the pathogenesis of human and experimental SpA.

Hematopoietic and mesenchymal stem cells: a promising new therapy for spondyloarthritis?

In the last years, a considerable progress has been made in the treatment of spondyloarthritides. Nonetheless, there remain a considerable number of patients who are unresponsive to all current therapies. Since the late 1990s, numerous trials have investigated the use of stem cell transplantation as a new approach for the treatment of autoimmune disease, particularly with hematopoietic stem cell transplantation. More recently, the research has focused on mesenchymal stem cell application due to their low immunogenicity and immunomodulatory properties. In this article, we summarize available data on hematopoietic stem cell and mesenchymal stem cell use for the treatment of spondyloarthritides and discuss the data gaps and possible research agenda in this area.

Interleukin-23 receptor polymorphism (rs10889677 A/C) in ankylosing spondylitis: Meta-analysis in Caucasian and Asian populations

BACKGROUND

The association between interleukin-23 receptor (IL23R) gene rs10889677 polymorphism and ankylosing spondylitis (AS) susceptibility was inconsistent in the recent literatures. A systematic review and meta-analysis was therefore performed.

METHODS

Online electronic databases were searched for relevant studies published up to November 2017. Meta-analyses were performed for the comparisons of allele (A versus C) and multiple genetic models, including dominant, recessive, heterozygous, and homozygous models using fixed or random effects models. Odds ratios (OR) with 95% confidence intervals (95%CI) were utilized to assess the potential relationship.

RESULTS

Sixteen studies containing 19 separate comparisons, totaling 6450 cases and 8009 controls were included. A significant association between rs10889677 A allele and AS susceptibility was detected (OR=1.136, 95%CI=1.043-1.236, P=0.003). Stratified analysis by ethnicity indicated that rs10889677 A allele was significantly associated with AS in Europeans (OR=1.192, 95%CI=1.080-1.315, P<0.001), but not Asians (OR=1.045, 95%CI=0.913-1.197, P=0.523). In addition, there were no significant associations between rs10889677 polymorphism and AS susceptibility in any of dominant, recessive, homozygous and heterozygous models.

CONCLUSION

This meta-analysis demonstrates that IL23R gene rs10889677 A allele confers increased risk of AS in Europeans, but its role in Asian populations needs further exploration.

IL-23R and IL-17A polymorphisms correlate with susceptibility of ankylosing spondylitis in a Southwest Chinese population

The association between the IL-23R and IL-17A polymorphisms and ankylosing spondylitis (AS) in the Southwest Chinese Population is still unclear. The purpose of this study is to detect the association between IL-23R and IL-17A polymorphisms and AS. A case-control study consisting of 486 AS patients and 480 healthy controls was performed. We used the high-resolution melting methods (HRM) to genotype five selected single nucleotide polymorphisms (SNPs), rs6693831, rs7517847, rs1884444, rs10889677 in the IL-23R gene and rs2275913 in the IL-17A gene. Meanwhile, the laboratory indexes were recorded. In this study, patients with genotype CC (p = 8.574E-8) and allele C (p = 3.206E-31) on SNP rs6693831 (IL-23R) showed decreased risk of AS. The genotype TT (p = 4.551E-6) and allele T (p = 0.02) on SNP rs1884444 (IL-23R) showed significant lower risk of AS. Individuals carrying the allele A of rs2275913 showed higher morbidity of AS (p = 0.04). We first detected that rs6693831 and rs1884444 in IL-23R gene and rs2275913 in IL-17A gene have genetic association with AS.

Haplotype of non-synonymous mutations within IL-23R is associated with susceptibility to severe malaria anemia in a P. falciparum holoendemic transmission area of Kenya

Background

Improved understanding of the molecular mechanisms involved in pediatric severe malarial anemia (SMA) pathogenesis is a crucial step in the design of novel therapeutics. Identification of host genetic susceptibility factors in immune regulatory genes offers an important tool for deciphering malaria pathogenesis. The IL-23/IL-17 immune pathway is important for both immunity and erythropoiesis via its effects through IL-23 receptors (IL-23R). However, the impact of IL-23R variants on SMA has not been fully elucidated.

Methods

Since variation within the coding region of IL-23R may influence the pathogenesis of SMA, the association between IL-23R rs1884444 (G/T), rs7530511 (C/T), and SMA (Hb < 6.0 g/dL) was examined in children (n = 369, aged 6–36 months) with P. falciparum malaria in a holoendemic P. falciparum transmission area.

Results

Logistic regression analysis, controlling for confounding factor of anemia, revealed that individual genotypes of IL-23R rs1884444 (G/T) [GT; OR = 1.34, 95% CI = 0.78–2.31, P = 0.304 and TT; OR = 2.02, 95% CI = 0.53–7.74, P = 0.286] and IL-23R rs7530511 (C/T) [CT; OR = 2.6, 95% CI = 0.59–11.86, P = 0.202 and TT; OR = 1.66, 95% CI = 0.84–3.27, P = 0.142] were not associated with susceptibility to SMA. However, carriage of IL-23R rs1884444T/rs7530511T (TT) haplotype, consisting of both mutant alleles, was associated with increased susceptibility to SMA (OR = 1.12, 95% CI = 1.07–4.19, P = 0.030).

Conclusion

Results presented here demonstrate that a haplotype of non-synonymous IL-23R variants increase susceptibility to SMA in children of a holoendemic P. falciparum transmission area.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2404-y) contains supplementary material, which is available to authorized users.

Secukinumab for rheumatology: development and its potential place in therapy

Rheumatic disease is not a single disorder, but a group of more than 100 diseases that affect joints, connective tissues, and/or internal organs. Although rheumatic diseases like rheumatoid arthritis (RA), psoriatic arthritis, and ankylosing spondylitis (AS) differ in their pathogenesis and clinical presentation, the treatment of these inflammatory disorders overlaps. Non-steroid anti-inflammatory drugs are used to reduce pain and inflammation. Additional disease-modifying anti-rheumatic drugs are prescribed to slowdown disease progression, and is in RA more frequently and effectively applied than in AS. Biologicals are a relatively new class of treatments that specifically target cytokines or cells of the immune system, like tumor necrosis factor alpha inhibitors or B-cell blockers. A new kid on the block is the interleukin-17 (IL-17) inhibitor secukinumab, which has been recently approved by the US Food and Drug Administration for moderate-to-severe plaque psoriasis, psoriatic arthritis, and AS. IL-17 is a proinflammatory cytokine that has an important role in host defense, but its proinflammatory and destructive effects have also been linked to pathogenic processes in autoimmune diseases like RA and psoriasis. Animal models have greatly contributed to further insights in the potential of IL-17 blockade in autoimmune and autoinflammatory diseases, and have resulted in the development of various potential drugs targeting the IL-17 pathway. Secukinumab (AIN457) is a fully human monoclonal antibody that selectively binds to IL-17A and recently entered the market under the brand name Cosentyx(®). By binding to IL-17A, secukinumab prevents it from binding to its receptor and inhibits its ability to trigger inflammatory responses that play a role in the development of various autoimmune diseases. With secukinumab being the first in class to receive Food and Drug Administration approval, this article will further focus on this new biologic agent and review the milestones in its development and marketing.

Constraints on Biological Mechanism from Disease Comorbidity Using Electronic Medical Records and Database of Genetic Variants

Patterns of disease co-occurrence that deviate from statistical independence may represent important constraints on biological mechanism, which sometimes can be explained by shared genetics. In this work we study the relationship between disease co-occurrence and commonly shared genetic architecture of disease. Records of pairs of diseases were combined from two different electronic medical systems (Columbia, Stanford), and compared to a large database of published disease-associated genetic variants (VARIMED); data on 35 disorders were available across all three sources, which include medical records for over 1.2 million patients and variants from over 17,000 publications. Based on the sources in which they appeared, disease pairs were categorized as having predominant clinical, genetic, or both kinds of manifestations. Confounding effects of age on disease incidence were controlled for by only comparing diseases when they fall in the same cluster of similarly shaped incidence patterns. We find that disease pairs that are overrepresented in both electronic medical record systems and in VARIMED come from two main disease classes, autoimmune and neuropsychiatric. We furthermore identify specific genes that are shared within these disease groups.

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.

Protective role of R381Q (rs11209026) polymorphism in IL-23R gene in immune-mediated diseases: A comprehensive review

Interleukin-23 (IL-23) is a regulator of cellular immune responses involved in controlling infection and autoimmune diseases. Strong evidence has shown that IL-23 plays a role in the maintenance of immune responses by influencing the proliferation and survival of IL-17-producing T-helper (TH)-17 cells. The critical role of the IL-23/TH17 axis in immune-mediated diseases has emerged from different studies. It has also been seen that polymorphisms in the IL-23 receptor (IL-23R) gene might influence IL-23 responses. Interestingly, a functional single nucleotide polymorphism (SNP) in the IL-23 receptor gene (IL-23R; rs11209026, 1142 G wild-type A reduced function, Arg381Gln, R381Q) seems to confer a measure of protection against development of inflammatory bowel disease (IBD; Crohn's disease, ulcerative colitis), ankylosing spondylitis, rheumatoid arthritis, psoriasis, thyroiditis, recurrent spontaneous abortion and asthma, suggesting that a perturbation in the IL-23 signaling pathway is likely to be relevant to the pathophysiology of these diseases. The aim of this review was to provide an evaluation of what is currently known about the protective role of R381Q variant in IL-23R gene in immune-based diseases.

Protective alleles and modifier variants in human health and disease

The combination of next-generation sequencing technologies and high-throughput genotyping platforms has revolutionized the pursuit of genetic variants that contribute towards disease. Furthermore, these technologies have provided invaluable insight into the genetic factors that prevent individuals from developing disease. Exploiting the evolutionary mechanisms that were designed by nature to help prevent disease is an attractive line of enquiry. Such efforts have the potential to generate a therapeutic target roadmap and rejuvenate the current drug-discovery pathway. By delineating the genomic factors that are protective against disease, there is potential to derive highly effective, genomically anchored medicines that assist in maintaining health.

Identification of Immune-Relevant Factors Conferring Sarcoidosis Genetic Risk

RATIONALE

Genetic variation plays a significant role in the etiology of sarcoidosis. However, only a small fraction of its heritability has been explained so far.

OBJECTIVES

To define further genetic risk loci for sarcoidosis, we used the Immunochip for a candidate gene association study of immune-associated loci.

METHODS

Altogether the study population comprised over 19,000 individuals. In a two-stage design, 1,726 German sarcoidosis cases and 5,482 control subjects were genotyped for 128,705 single-nucleotide polymorphisms using the Illumina Immunochip for the screening step. The remaining 3,955 cases, 7,514 control subjects, and 684 parents of affected offspring were used for validation and replication of 44 candidate and two established risk single-nucleotide polymorphisms.

MEASUREMENTS AND MAIN RESULTS

Four novel susceptibility loci were identified with genome-wide significance in the European case-control populations, located on chromosomes 12q24.12 (rs653178; ATXN2/SH2B3), 5q33.3 (rs4921492; IL12B), 4q24 (rs223498; MANBA/NFKB1), and 2q33.2 (rs6748088; FAM117B). We further defined three independent association signals in the HLA region with genome-wide significance, peaking in the BTNL2 promoter region (rs5007259), at HLA-B (rs4143332/HLA-B*0801) and at HLA-DPB1 (rs9277542), and found another novel independent signal near IL23R (rs12069782) on chromosome 1p31.3.

CONCLUSIONS

Functional predictions and protein network analyses suggest a prominent role of the drug-targetable IL23/Th17 signaling pathway in the genetic etiology of sarcoidosis. Our findings reveal a substantial genetic overlap of sarcoidosis with diverse immune-mediated inflammatory disorders, which could be of relevance for the clinical application of modern therapeutics.

The immunogenetics of Behçet's disease: A comprehensive review

Behçet's disease is a chronic multisystem inflammatory disorder characterized mainly by recurrent oral ulcers, ocular involvement, genital ulcers, and skin lesions, presenting with remissions and exacerbations. It is thought that both environmental and genetic factors contribute to its onset and development. Although the etiology of Behçet's disease remains unclear, recent immunogenetic findings are providing clues to its pathogenesis. In addition to the positive association of HLA-B*51, which was identified more than four decades ago, and which has since been confirmed in multiple populations, recent studies report additional independent associations in the major histocompatibility complex class I region. HLA-B*15, -B*27, -B*57, and -A*26 are independent risk factors for Behçet's disease, while HLA-B*49 and -A*03 are independent class I alleles that are protective for Behçet's disease. Genome-wide association studies have identified associations with genome-wide significance (P < 5 × 10(-8)) in the IL23R-IL12RB2, IL10, STAT4, CCR1-CCR3, KLRC4, ERAP1, TNFAIP3, and FUT2 loci. In addition, targeted next-generation sequencing has revealed the involvement of rare nonsynonymous variants of IL23R, TLR4, NOD2, and MEFV in Behçet's disease pathogenesis. Significant differences in gene function or mRNA expression associated with the risk alleles of the disease susceptibility loci suggest which genes in a disease-associated locus influence disease pathogenesis. These genes encompass both innate and adaptive immunity and confirm the importance of the predominant polarization towards helper T cell (Th) 1 versus Th2 cells, and the involvement of Th17 cells. In addition, epistasis observed between HLA-B*51 and the risk coding haplotype of the endoplasmic reticulum-associated protease, ERAP1, provides a clue that an HLA class I-peptide presentation-based mechanism contributes to this complex disease.

Genetics of psoriasis

Psoriasis is a common and debilitating immune-mediated skin disease with a complex genetic basis. Genetic studies have provided critical insights into the pathogenesis of disease. This article focuses on the results of genetic association studies, which provide evidence that psoriasis susceptibility genes are involved in innate and adaptive immunity and skin barrier functions. The potential for disease stratification and the development of more effective treatments with fewer side effects using genetic data are highlighted.

Investigation of interleukin-12, interleukin-17 and interleukin-23 receptor gene polymorphisms in alopecia areata

Objective

To investigate the distribution of interleukin (IL)-12 ( IL12; 1188A/C), IL17 (A7488G) and IL-23 receptor ( IL23R; +2199A/C) gene polymorphisms in patients with alopecia areata.

Methods

Patients with alopecia areata and healthy controls were enrolled in this case–control study. Genotyping of the IL12 (1188A/C), IL17 (A7488G) and IL23R (+2199A/C) polymorphisms was undertaken. Genotype frequencies were compared between the two groups.

Results

The study enrolled 100 patients with alopecia areata and 71 control subjects. No significant differences were found in the frequencies for the IL12 and IL23R gene polymorphisms between the patient and control groups. The IL17 GG genotype was significantly more common and the IL17 GA genotype was significantly less common in patients with alopecia areata compared with controls, but only 10% of patients had the GG genotype.

Conclusion

The IL17 GG genotype was associated with susceptibility for alopecia areata, but this genotype was only present in a small number of patients. The IL12 and IL23R gene polymorphisms were not found to have a significant association with alopecia areata.

The IL-23-IL-17 axis in inflammatory arthritis. Nat Rev Rheumatol. 2015;11:415-429. [PMID: 25907700 DOI: 10.1038/nrrheum.2015.53]

The discovery that the IL-23-IL-17 immune pathway is involved in many models of autoimmune disease has changed the concept of the role of T-helper cell subsets in the development of autoimmunity. In addition to TH17 cells, IL-17 is also produced by other T cell subsets and innate immune cells; which of these IL-17-producing cells have a role in tissue inflammation, and the timing, location and nature of their role(s), is incompletely understood. The current view is that innate and adaptive immune cells expressing the IL-23 receptor become pathogenic after exposure to IL-23, but further investigation into the role of IL-23 and IL-17 at different stages in the development and progression of chronic (destructive) inflammatory diseases is needed. Rheumatoid arthritis (RA) and spondyloarthritis (SpA) are the two most common forms of chronic immune-mediated inflammatory arthritis, and the IL-23-IL-17 axis is thought to have a critical role in both. This Review discusses the basic mechanisms of these cytokines in RA and SpA on the basis of findings from disease-specific animal models as well as human ex vivo studies. Promising therapeutic applications to modulate this immune pathway are in development or have already been approved. Blockade of IL-17 and/or TH17-cell activity in combination with anti-TNF therapy might be a successful approach to achieving stable remission or even prevention of chronic immune-mediated inflammatory diseases.

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.

HLA alleles and HLA-B27 haplotypes associated with susceptibility and severity of ankylosing spondylitis in a Portuguese population

Human leukocyte antigen (HLA)-B27 is the mostly known major histocompatibility complex (MHC) gene associated with ankylosing spondylitis (AS). Nonetheless, there is substantial evidence that other MHC genes appear to be associated with the disease, although it has not yet been established whether these associations are driven by direct associations or by linkage disequilibrium (LD) mechanisms. We aimed to investigate the contributions of HLA class I and II alleles and B27-haplotypes for AS in a case-control study. A total of 188 HLA-B27 AS cases and 189 HLA-B27 healthy controls were selected and typed for HLA class I and II by the Luminex polymerase chain reaction-sequence specific oligonucleotide probe (PCR-SSOP) method. Allelic and haplotypic distributions were estimated by maximum likelihood method using Arlequin v3.11 and statistical analysis were performed by Stata10.1. No associations were found between non-HLA-B27 loci and AS susceptibility, but several associations were observed for phenotypic features of the disease. DRB1*08 was identified as a risk factor for uveitis and DQB1*04 seems to provide protection for AS severity (functional, metrological and radiological indexes). A*02/B27/C*02/DRB1*01/DQB1*05 [P<0.0001; odds ratio (OR) = 39.06; 95% confidence interval (CI) (2.34-651)] is the only haplotype that seems to confer susceptibility to AS. Moreover, the haplotype A*02/B27/C*01/DRB1*08/DQB1*04 seems to provide protection for disease functional and radiological repercussions. Our findings are compatible with the hypothesis that other genes within the HLA region besides HLA-B27 might play some role in AS susceptibility and severity.

Differential expression and function of human IL-12Rβ2 polymorphic variants

The receptor for interleukin-12, formed by IL-12Rβ1 and IL-12Rβ2, mediates the type I immune responses of various types of lymphocytes. Polymorphisms in IL12RB2, the gene encoding IL-12Rβ2, were reported to be associated with several immune related diseases, such as Crohn's disease. Because the IL23R and IL12RB2 genes are located in close proximity on the genome, the reported associations might also be attributable to linked polymorphisms in IL23R, which were found to be associated with immune related diseases as well. To clarify the role of IL-12Rβ2 in immune diseases, we investigated the functional consequences of thirteen amino acid substitutions in IL-12Rβ2. We developed a model with retroviral expression of IL-12Rβ2 in B cell lines. With the use of this model the expression and function of the variants was compared within the same genetic background. Four of the IL-12Rβ2 variants, N271Y, R313G, A604V and L808R showed reduced IL-12 responses compared to the wild type variant. Two of these are relatively common in some populations and may be used in future association studies to reveal a role for IL-12 in infectious and/or immune related diseases.

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

Purpose

The interleukin-23 receptor (IL-23R) has been shown to be associated with ankylosing spondylitis (AS) in many different populations. This study examined whether IL-23R polymorphisms were associated with susceptibility to this disease in a Chinese Han population.

Methods

Three single-nucleotide polymorphisms (SNP), rs7517847, rs11209032, and rs17375018, were genotyped in 291 AS patients and 312 age-, sex-, and ethnically matched healthy controls using a polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) assay.

Results

The genotype and allele frequencies of rs17375018, rs7517847, and rs11209032 were not different between the patients with AS and the healthy controls. On the one hand, stratification analysis indicated that the rs17375018 GG genotype and the G allele were increased in AS patients who were HLA-B27 positive (corrected p = 0.024, odds ratio [OR] 2.35, 95% CI 1.30–4.24; p_c = 0.006, OR 1.98, 95% CI 1.28–3.07, respectively). On the other hand, the analysis according to clinical characteristics showed a significantly increased prevalence of the homozygous rs17375018 GG genotype and the G allele in patients with AS and uveitis compared with the controls (p_c = 0.024 and p_c = 0.024, respectively). In addition, haplotype analysis performed with the SHEsis platform revealed no significant difference concerning the haplotypes between AS patients and healthy controls.

Conclusions

In this study, the results suggested that the rs17375018 of IL23R was positively associated with HLA-B27-positive AS and that the rs17375018 GG of IL-23R was associated with AS concomitant with uveitis. We found no evidence for an association between the other two SNPs of IL-23R and AS.

Lack of associations between two previously identified susceptible single nucleotide polymorphisms of interleukin-23 receptor gene and ankylosing spondylitis: a replication study in a Chinese Han population

Background

The human leukocyte antigen (HLA)-B27 gene is considered to be a major gene associated with predisposition to ankylosing spondylitis (AS); however, studies have demonstrated that non-HLA-B27 genes also contribute substantially to the susceptibility to AS. Two single nucleotide polymorphisms (SNPs), rs1004819 and rs10889677, of the interleukin-23 receptor (IL-23R) gene have been shown to be associated with AS susceptibility in European populations. However, ethnicity factors contribute to population splitting and genetic variation, and ethnic-specific genetic association studies are needed to validate these associations in patients from different ethnic backgrounds. This study therefore aimed to replicate the associations between these two SNPs and AS susceptibility in a Chinese Han population.

Methods

A total of 195 AS patients and 203 normal controls were recruited in this study. Two IL-23R gene SNPs, rs1004819 and rs10889677 were selected. Genotyping was performed in all subjects using the TaqMan probe method. Genotype and allele frequencies were compared between AS patients and normal controls by χ² tests.

Results

There were no significant differences in either the genotype frequencies (TT 36.4%, TC 48.7% and CC 14.9% in AS patients; TT 35.0%, TC 50.0% and CC 15.0% in normal controls) or allele frequencies (T 60.8% and C 39.2% in AS patients; T 60.0% and C 40.0% in normal controls) of rs1004819 between AS patients and normal controls (P > 0.05). In addition, both the genotype frequencies (AA 51.3%, AC 43.1% and CC 5.6% in AS patients; AA 57.6%, AC 35.5% and CC 6.9% in normal controls) and allele frequencies (A 72.8% and C 27.2% in AS patients; A 75.4% and C 24.6% in normal controls) of rs10889677 were also comparable between AS patients and normal controls (P > 0.05).

Conclusions

This study found no evidence for an association between either of the two previously identified AS-susceptibility IL-23R SNPs (rs1004819 and rs10889677) and onset of AS, indicating a possible difference in pathogenesis of AS between Chinese and European patients.

Evidence that autophagy, but not the unfolded protein response, regulates the expression of IL-23 in the gut of patients with ankylosing spondylitis and subclinical gut inflammation

OBJECTIVES

Interleukin (IL)-23 has been implicated in the pathogenesis of ankylosing spondylitis (AS). The aim of the study was to clarify the mechanisms underlying the increased IL-23 expression in the gut of AS patients.

METHODS

Consecutive gut biopsies from 30 HLA-B27(+) AS patients, 15 Crohn's disease (CD) patients and 10 normal subjects were obtained. Evidence for HLA-B27 misfolding was studied. Unfolded protein response (UPR) and autophagy were assessed by RT-PCR and immunohistochemistry. The contribution of UPR and autophagy in the regulation of IL-23 expression was evaluated in in vitro experiments on isolated lamina propria mononuclear cells (LPMCs).

RESULTS

Intracellular colocalisation of SYVN1 and FHCs but not a significant overexpression of UPR genes was observed in the gut of AS patients. Conversely, upregulation of the genes involved in the autophagy pathway was observed in the gut of AS and CD patients. Immunohistochemistry showed an increased expression of LC3II, ATG5 and ATG12 but not of SQSTM1 in the ileum of AS and CD patients. LC3II was expressed among infiltrating mononuclear cells and epithelial cells resembling Paneth cells (PC) and colocalised with ATG5 in AS and CD. Autophagy but not UPR was required to modulate the expression of IL-23 in isolated LPMCs of AS patients with chronic gut inflammation, CD patients and controls.

CONCLUSIONS

Our data suggest that HLA-B27 misfolding occurs in the gut of AS patients and is accompanied by activation of autophagy rather than a UPR. Autophagy appears to be associated with intestinal modulation of IL-23 in AS.

The IL23R A/Gln381 allele promotes IL-23 unresponsiveness in human memory T-helper 17 cells and impairs Th17 responses in psoriasis patients

We and others have shown that the minor, nonconserved allele Gln381 of the Arg381Gln single-nucleotide polymorphism (rs11209026G>A) of the IL-23 receptor gene (IL23R) protects against psoriasis. Moreover, we have recently shown impaired IL-23-induced IL-17A production and STAT-3 phosphorylation in Th17 cells generated in vitro from healthy individuals heterozygous for the protective A allele (GA). However, the biological effect of this variant has not been determined in homozygous carriers of the protective A allele (AA), nor in psoriatic patients. Here we expand our functional investigation of the IL23R Arg381Gln gene variant to include AA homozygous individuals. By using isolated memory CD4+ T cells, we found attenuated IL-23-induced Th17 response in heterozygous individuals. Moreover, we found that AA homozygous individuals were strikingly unresponsive to IL-23, with minimal or no IL-17A and IL-17F production and failure of human memory Th17 cell survival/expansion. Finally, IL-23-induced Th17 response was also attenuated in age- and sex-matched GA versus GG psoriatic patients undergoing systemic treatment. Taken together, our data provide evidence for an allele-dosage effect for IL-23R Gln381 and indicate that common gene alleles associated with complex diseases might have biological effects of considerable magnitude in homozygous carriers.

Therapeutic potency of Poly I:C in HSV-induced inflammation through up-regulation of IL-15 receptor alpha

Interleukin-15 receptor alpha (IL-15Rα) forms stable complex with IL-15 on the cell surface of activated monocytes and mediates the proliferation of memory CD8+ T cells. Recent studies informed that polyinosinic:polycytidylic acid (Poly I:C) is an immunostimulant which boosts the generation of memory T cells through induction of IL-15Rα. The aim of this study is to evaluate the relevance of IL-15Rα in Herpes simplex virus (HSV)-induced Behçet's disease (BD) mouse model and BD patients. The frequencies of IL-15Rα expression in PBMCs of BD patients and BD-like symptomatic mice were analyzed by flow cytometry. In addition, Poly I:C supplementation could reduce inflammation through the up-regulation of memory T cells and IL-15Rα+ cells accompany with down-regulation of pro-inflammatory cytokine, IL-17A in BD mice. In BD patients, the frequencies of IL-15Rα expression in PBMCs were also significantly different between the inactive and active disease states. These results suggest that IL-15Rα is a relevant factor in BD.