Functional studies on the IBD susceptibility gene IL23R implicate reduced receptor function in the protective genetic variant R381Q

Effects of DNA methylation and its application in inflammatory bowel disease (Review)

Inflammatory bowel disease (IBD) is marked by persistent inflammation, and its development and progression are linked to environmental, genetic, immune system and gut microbial factors. DNA methylation (DNAm), as one of the protein modifications, is a crucial epigenetic process used by cells to control gene transcription. DNAm is one of the most common areas that has drawn increasing attention recently, with studies revealing that the interleukin (IL)‑23/IL‑12, wingless‑related integration site, IL‑6‑associated signal transducer and activator of transcription 3, suppressor of cytokine signaling 3 and apoptosis signaling pathways are involved in DNAm and in the pathogenesis of IBD. It has emerged that DNAm‑associated genes are involved in perpetuating the persistent inflammation that characterizes a number of diseases, including IBD, providing a novel therapeutic strategy for exploring their treatment. The present review discusses DNAm‑associated genes in the pathogenesis of IBD and summarizes their application as possible diagnostic, prognostic and therapeutic biomarkers in IBD. This may provide a reference for the particular form of IBD and its related methylation genes, aiding in clinical decision‑making and encouraging therapeutic alternatives.

Interleukin 23 receptor: Expression and regulation in immune cells

The importance of IL-23 and its specific receptor, IL-23R, in the pathogenesis of several chronic inflammatory diseases has been established, but the underlying pathological mechanisms are not fully understood. This review focuses on IL-23R expression and regulation in immune cells.

IL-12 and IL-23 pathway inhibition in inflammatory bowel disease

Interleukin-12 (IL-12) and interleukin-23 (IL-23), which belong to the IL-12 family of cytokines, have a key role in intestinal homeostasis and inflammation and are implicated in the pathogenesis of inflammatory bowel disease. Upon their secretion by antigen-presenting cells, they exert both pro-inflammatory and anti-inflammatory receptor-mediated effects. An increased understanding of these biological effects, particularly the pro-inflammatory effects mediated by IL-12 and IL-23, has led to the development of monoclonal antibodies that target a subunit common to IL-12 and IL-23 (p40; targeted by ustekinumab and briakinumab), or the IL-23-specific subunit (p19; targeted by risankizumab, guselkumab, brazikumab and mirikizumab). This Review provides a summary of the biology of the IL-12 family cytokines IL-12 and IL-23, discusses the role of these cytokines in intestinal homeostasis and inflammation, and highlights IL-12- and IL-23-directed drug development for the treatment of Crohn's disease and ulcerative colitis.

Interleukins (IL-23 and IL-27) serum levels: Relationships with gene polymorphisms and disease patterns in multiple sclerosis patients under treatment with interferon and glatiramer acetate

Background

interleukin 23 (IL-23) is an important factor involved in the survival and proliferation of T helper 17 cells (Th17), known for their implication in multiple sclerosis (MS). By contrast, IL-27 regulates and modulates the function of T lymphocytes, in particular as a suppressor of Th17 differentiation. The aims of the study were i) to test the association of cytokines with the clinical and genetic characteristics in each of the multiple sclerosis groups (CIS - clinically isolated syndrome, RRMS - relapsing-remitting MS and SPMS - Secondary progressive MS) and ii) to evaluate the association between serum levels of IL-23 and IL-27 with T4730C (IL-27), A964G (IL-27) and R381Q (IL-23) gene polymorphisms in RRMS patients.

Methods

Blood samples were obtained from 82 patients diagnosed with MS under treatment with glatiramer acetate (GA), interferon beta (IFN) 1 A and 1 B. IL-23 and IL-27 serum concentrations were measured by enzyme-linked immunosorbant assay (ELISA). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used in order to determine the genotypes for R381Q (IL-23) polymorphisms, T4730C (IL-27) and A964G (IL-27).

Results

Patients with SPMS, RRMS and CIS respectively differed significantly regarding age distribution (p = 0.003) but the studied MS groups were similar regarding age at disease onset (p = 0.528) and treatment type (p = 0.479). A significant increase of mean serum IL-27 was noticed in cases with early onset (age at disease onset <28 years) of RRMS (mean difference: 4.2 pg/ml, 95% CI: 0.8-5.3 pg/ml), compared to cases with later onset of RRMS (age at disease onset ≥28 years). RRMS patients with wild GG genotype of R381Q (IL-23) showed a significant increase of mean serum IL-23 than patients with variant AG genotype (mean difference: 115.1 pg/ml, 95% CI: 8.6-221.6 pg/ml). A trend for a higher increase in means of serum IL-23 (p = 0.086) was observed in RRMS patients carriers of AA genotype of A964G (IL-27) polymorphism in comparison with patients with AG or GG genotypes. We found no significant monotonic correlation of IL-27, IL-23 serum levels with age at disease onset (years) and duration of disease (p > 0.05) in the CIS and SPMS group respectively but a significant correlation between IL-23 and the duration of disease-modifying treatment was noticed only in the SPMS group.

Conclusions

The results of the current study suggest an association between IL-23 levels and the R381Q gene polymorphism and also a relationship between IL-27 serum levels and early age at disease onset in RRMS patients.

Interleukin-23 in the Pathogenesis of Inflammatory Bowel Disease and Implications for Therapeutic Intervention

The interleukin-23 [IL-23] cytokine, derived predominantly from macrophages and dendritic cells in response to microbial stimulation, has emerged as a critical promoter of chronic intestinal inflammation. Genome-wide association studies linking variants in IL23R to disease protection, bolstered by experimental evidence from colitis models, and the successful application of therapies against the IL-12/IL-23 shared p40 subunit in the treatment of inflammatory bowel disease [IBD] all provide compelling evidence of a crucial role for IL-23 in disease pathogenesis. Moreover, targeting the p19 subunit specific for IL-23 has shown considerable promise in recent phase 2 studies in IBD. The relative importance of the diverse immunological pathways downstream of IL-23 in propagating mucosal inflammation in the gut, however, remains contentious. Here we review current understanding of IL-23 biology and explore its pleiotropic effects on T cells, and innate lymphoid, myeloid and intestinal epithelial cells in the context of the pathogenesis of IBD. We furthermore discuss these pathways in the light of recent evidence from clinical trials and indicate emerging targets amenable to therapeutic intervention and translation into clinical practice.

Pattern Recognition Receptor Signaling and Cytokine Networks in Microbial Defenses and Regulation of Intestinal Barriers: Implications for Inflammatory Bowel Disease

Inflammatory bowel disease is characterized by defects in epithelial function and dysregulated inflammatory signaling by lamina propria mononuclear cells including macrophages and dendritic cells in response to microbiota. In this review, we focus on the role of pattern recognition receptors in the inflammatory response as well as epithelial barrier regulation. We explore cytokine networks that increase inflammation, regulate paracellular permeability, cause epithelial damage, up-regulate epithelial proliferation, and trigger restitutive processes. We focus on studies using patient samples as well as speculate on pathways that can be targeted to more holistically treat patients with inflammatory bowel disease.

Aconitate Decarboxylase 1 Deficiency Exacerbates Mouse Colitis Induced by Dextran Sodium Sulfate

Ulcerative colitis is a complex inflammatory bowel disorder disease that can induce rectal and colonic dysfunction. Although the prevalence of IBD in Western countries is almost 0.5% of the general population, genetic causes are still not fully understood. In a recent discovery, itaconate was found to function as an immune-modulating metabolite in mammalian immune cells, wherein it is synthesized as an antimicrobial compound from the citric acid cycle intermediate cis-aconitic acid. However, the association between the Acod1 (Aconitate decarboxylase 1)-itaconate axis and ulcerative colitis has rarely been studied. To elucidate this, we established a DSS-induced colitis model with Acod1-deficient mice and then measured the mouse body weights, colon lengths, histological changes, and cytokines/chemokines in the colon. We first confirmed the upregulation of Acod1 RNA and protein expression levels in DSS-induced colitis. Then, we found that colitis symptoms, including weight loss, the disease activity index, and colon shortening, were worsened by the depletion of Acod1. In addition, the extent of intestinal epithelial barrier breakdown, the extent of immune cell infiltration, and the expression of proinflammatory cytokines and chemokines in Acod1-deficient mice were higher than those in wild-type mice. Finally, we confirmed that 4-octyl itaconate (4-OI) alleviated DSS-induced colitis in Acod1-deficient mice and decreased the expression of inflammatory cytokines and chemokines. To our knowledge, this study is the first to elucidate the role of the Acod1-itaconate axis in colitis. Our data clearly showed that Acod1 deletion resulted in severe DSS-induced colitis and substantial increases in inflammatory cytokine and chemokine levels. Our results suggest that Acod1 may normally play an important regulatory role in the pathogenesis of colitis, demonstrating the potential for novel therapies using 4-OI.

Potential Contribution of IL-27 and IL-23 Gene Polymorphisms to Multiple Sclerosis Susceptibility: An Association Analysis at Genotype and Haplotype Level

(1) Background: interleukin 23 (IL-23) and interleukin 27 (IL-27) modulate the activity of T helper 17 cells (Th17) with critical roles in autoimmune diseases and multiple sclerosis (MS). The genes responsible for cytokine generation are highly influenced by the presence of single nucleotide polymorphisms (SNP) in main regions such as regulatory sequences or in promoter regions, contributing to disease susceptibility and evolution. The present study analyzed the associations of IL-23 and IL-27 SNPs with susceptibility to multiple sclerosis. (2) Methods: We performed a case-control study including 252 subjects: 157 patients diagnosed with MS and 95 controls. We used polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to determine the genotypes for IL-27 T4730C (rs 181206), IL-27 A964G (rs 153109), and IL-23 receptor gene (IL-23R) G1142A (rs 11209026). (3) Results: The IL27-T4730C gene polymorphism was significantly associated with an increased odds of MS under the dominant genetic model (TC + CC variant genotypes, adjusted odds ratio OR = 4.06, 95% CI: 2.14–7.83, p-value = 0.000007, Q-value = 0.000063). Individuals carrying the IL-27 A924G variant (AG + GG) genotype presented higher odds of MS compared to non-carriers under the dominant model (adjusted OR = 1.93, 95% CI: 1.05–3.51, p-value = 0.0324, Q-value = 0.05832) and the allelic genetic model (unadjusted p-value = 0.015, OR = 1.58, 95% CI: 1.09–2.28), while IL-23-R381Q SNP conferred a decreased odds of MS under a codominant model of inheritance (adjusted OR = 0.26, 95% CI: 0.08–0.92, p-value = 0.0276, Q-value = 0.058) and an allelic model (unadjusted p-value = 0.008, OR = 0.23, 95% CI: 0.07–0.75). In an additive model with adjustment for age group (≤40 years vs. >40 years), sex and smoking, patients carrying the G-C (A964G, T4730C) haplotype had a 3.18 increased risk (95% CI: 1.74–5.81, p < 0.001) to develop multiple sclerosis. (4) Conclusions: The results of the current study showed a significant relationship of IL-27-A964G and IL-27-T4730C polymorphisms with increased risk of MS, and also the protective role of the IL-23-R381Q polymorphism. Moreover, the haplotype-based analysis proposed the mutant G-C (A924G, T4730C) as a significant risk haplotype for the development of MS.

Current status and relevance of single nucleotide polymorphisms in IL-6-/IL-12-type cytokine receptors

Cytokines control immune related events and are critically involved in a plethora of patho-physiological processes including autoimmunity and cancer development. In rare cases, single nucleotide polymorphisms (SNPs) or single nucleotide variations (SNVs) in cytokine receptors eventually cause detrimental ligand-independent, constitutive activation of signal transduction. Most SNPs have, however, no or only marginal influences on gene expression, protein stability, localization and function and thereby only slightly affecting pathogenesis probability. The SNP database (dbSNP) is an archive for a broad collection of polymorphisms in which SNPs are categorized and marked with a locus accession number "reference SNP" (rs). Here, we engineered an algorithm to directly align dbSNP information to DNA and protein sequence information to clearly illustrate a genetic SNP landscape exemplified for all tall cytokine receptors of the IL-6/IL-12 family, including IL-23R, IL-12Rβ1, IL-12Rβ2, gp130, LIFR, OSMR and WSX-1. This information was complemented by a comprehensive literature summary and structural insights of relevant disease-causing SNPs in cytokine/cytokine receptor interfaces. In summary, we present a general strategy with potential to apply to other cytokine receptor networks.

IL-12 and IL-23-Close Relatives with Structural Homologies but Distinct Immunological Functions

Cytokines of the IL-12 family show structural similarities but have distinct functions in the immune system. Prominent members of this cytokine family are the pro-inflammatory cytokines IL-12 and IL-23. These two cytokines share cytokine subunits and receptor chains but have different functions in autoimmune diseases, cancer and infections. Accordingly, structural knowledge about receptor complex formation is essential for the development of new therapeutic strategies preventing and/or inhibiting cytokine:receptor interaction. In addition, intracellular signaling cascades can be targeted to inhibit cytokine-mediated effects. Single nucleotide polymorphisms can lead to alteration in the amino acid sequence and thereby influencing protein functions or protein–protein interactions. To understand the biology of IL-12 and IL-23 and to establish efficient targeting strategies structural knowledge about cytokines and respective receptors is crucial. A highly efficient therapy might be a combination of different drugs targeting extracellular cytokine:receptor assembly and intracellular signaling pathways.

Differential regulation of JAK/STAT-signaling in patients with ulcerative colitis and Crohn’s disease

In 2018, the pan-Janus kinase (JAK) inhibitor tofacitinib was launched for the treatment of ulcerative colitis (UC). Although tofacitinib has proven efficacious in patients with active UC, it failed in patients with Crohn’s disease (CD). This finding strongly hints at a different contribution of JAK signaling in both entities. Here, we review the current knowledge on the interplay between the JAK/signal transducer and activator of transcription (STAT) pathway and inflammatory bowel diseases (IBD). In particular, we provide a detailed overview of the differences and similarities of JAK/STAT-signaling in UC and CD, highlight the impact of the JAK/STAT pathway in experimental colitis models and summarize the published evidence on JAK/STAT-signaling in immune cells of IBD as well as the genetic association between the JAK/STAT pathway and IBD. Finally, we describe novel treatment strategies targeting JAK/STAT inhibition in UC and CD and comment on the limitations and challenges of the new drug class.

Genetic Analysis of Ulcerative Colitis in Japanese Individuals Using Population-specific SNP Array

BACKGROUND

To clarify the genetic background of ulcerative colitis (UC) in the Japanese population, we conducted a genome-wide association study (GWAS) using a population-specific single nucleotide polymorphism (SNP) array.

METHODS

We performed a GWAS and replication study including 1676 UC patients and 2381 healthy controls. The probability of colectomy was compared between genotypes of rs117506082, the top hit SNP at HLA loci, by the Kaplan-Meier method. We studied serum expression of miR-622, a newly identified candidate gene, from 32 UC patients and 8 healthy controls by quantitative reverse-transcription polymerase chain reaction.

RESULTS

In the GWAS, only the HLA loci showed genome-wide significant associations with UC (rs117506082, P = 6.69E-28). Seven nominally significant regions included 2 known loci, IL23R (rs76418789, P = 6.29E-7) and IRF8 (rs16940202, P = 1.03E-6), and 5 novel loci: MIR622 (rs9560575, P = 8.23E-7), 14q31 (rs117618617, P = 1.53E-6), KAT6B (rs12260609, P = 1.81E-6), PAX3-CCDC140-SGPP2 (rs7589797, P = 2.87E-6), and KCNA2 (rs118020656, P = 4.01E-6). Combined analysis revealed that IL23R p.G149R (rs76418789, P = 9.03E-11; odds ratio [OR], 0.51) had genome-wide significant association with UC. Patients with GG genotype of rs117506082 had a significantly lower probability of total colectomy than those with the GA+AA genotype (P = 1.72E-2). Serum expression of miR-622 in patients with inactive UC tended to be higher than in healthy controls and patients with active UC (inactive UC vs healthy controls, P = 3.03E-02; inactive UC vs active UC, P = 6.44E-02).

CONCLUSIONS

IL23R p.G149R is a susceptibility locus for UC in Japanese individuals. The GG genotype of rs117506082 at HLA loci may predict a better clinical course.

Infectious Complications of Biological and Small Molecule Targeted Immunomodulatory Therapies

The past 2 decades have seen a revolution in our approach to therapeutic immunosuppression. We have moved from relying on broadly active traditional medications, such as prednisolone or methotrexate, toward more specific agents that often target a single receptor, cytokine, or cell type, using monoclonal antibodies, fusion proteins, or targeted small molecules. This change has transformed the treatment of many conditions, including rheumatoid arthritis, cancers, asthma, and inflammatory bowel disease, but along with the benefits have come risks. Contrary to the hope that these more specific agents would have minimal and predictable infectious sequelae, infectious complications have emerged as a major stumbling block for many of these agents. Furthermore, the growing number and complexity of available biologic agents makes it difficult for clinicians to maintain current knowledge, and most review articles focus on a particular target disease or class of agent. In this article, we review the current state of knowledge about infectious complications of biologic and small molecule immunomodulatory agents, aiming to create a single resource relevant to a broad range of clinicians and researchers. For each of 19 classes of agent, we discuss the mechanism of action, the risk and types of infectious complications, and recommendations for prevention of infection.

IL23 Promotes Antimicrobial Pathways in Human Macrophages, Which Are Reduced With the IBD-Protective IL23R R381Q Variant

BACKGROUND & AIMS

Interleukin (IL)23 is a major contributor to inflammatory bowel disease (IBD) pathogenesis and is being pursued as a therapeutic target, both through targeting IL23 alone or in combination with IL12. Unexpected trial outcomes highlight the importance of understanding the cell types through which IL23 regulates immune responses, and how IL23 and IL12 compare in these responses. Macrophages are key players in IBD, and IL23 recently was found to promote inflammatory outcomes in human macrophages. This raises the possibility that IL23 may be required for additional essential macrophage functions, in particular microbial clearance, such that either blocking the IL23 pathway or the IL23R-R381Q IBD-protective variant may reduce macrophage-mediated microbial clearance.

METHODS

We analyzed protein expression, signaling, bacterial uptake, and intracellular bacterial clearance in human monocyte-derived macrophages through Western blot, flow cytometry, and gentamicin protection.

RESULTS

Autocrine/paracrine IL23 was critical for optimal levels of pattern-recognition-receptor (PRR)-induced intracellular bacterial clearance in human macrophages. Mechanisms regulated by IL23 included induction of pyruvate dehydrogenase kinase 1-dependent bacterial uptake, and up-regulation of reactive oxygen species through nicotinamide adenine dinucleotide phosphate oxidase members, nitric oxide synthase 2, and autophagy through ATG5 and ATG16L1. Complementing these pathways in IL23R-deficient macrophages restored PRR-induced bacterial uptake and clearance. Janus kinase 2, TYK2, and STAT3 were required for IL23-induced mechanisms. IL23 and IL12 induced antimicrobial pathways to similar levels in human macrophages. Relative to IL23R-R381, transfected IL23R-Q381, or monocyte-derived macrophages from IL23R-Q381 carriers showed reduced bacterial uptake and clearance.

CONCLUSIONS

We identify that autocrine/paracrine IL23 is required for optimal PRR-enhanced macrophage bacterial uptake and intracellular bacterial clearance, define mechanisms regulating IL23R-induced bacterial clearance, and determine how the IBD-protective IL23R-R381Q variant modulates these processes.

Role of the IL-23 pathway in the pathogenesis and treatment of enthesitis in psoriatic arthritis

INTRODUCTION

Enthesitis is a key feature of spondyloarthritis (SpA). Several studies have underlined the role of interleukin (IL)-23 in SpA development as a crucial cytokine in the pathogenesis of enthesitis.

AREA COVERED

This review summarizes recent evidence of the role of IL-23 in the pathogenesis of and as a target of the treatment of enthesitis. We review the definition, diagnosis and clinical impact of enthesitis and its connection with microbial infections, gut dysbiosis, and mechanical stress. We also review clinical trials and real-life studies of drugs targeting the p19 or p40 subunits of IL-23.

EXPERT OPINION

Novel therapies targeting the p19 or p40 subunit of IL-23 appear to be promising treatment options for patients with enthesitis. Although we are currently unable to identify the best therapeutic window to target IL-23 in SpA disease evolution, the promising ability of this therapy to control the gut-entheseal axis is increasing our knowledge of SpA pathogenesis.

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.

Progress in our understanding of the pathogenesis of ankylosing spondylitis

AS is a common rheumatic condition characterized by inflammation and new bone formation. The pathogenesis of AS is likely multifactorial and has not been fully elucidated to date. A major genetic role has been demonstrated. The strongest genetic association is with HLA B27. Numerous other associated genetic polymorphisms have been identified, including those affecting the type 17 immune pathway, although the precise link between genetics and pathogenesis remains unexplained. Several immunological alterations, together with recent therapeutic advances, support a central role for IL-23- and IL-17-producing immune cells in disease pathogenesis. Recently, perturbations of gut microbiota of AS patients have further catalysed research and offer potential for future therapeutic intervention. In this review we outline the genetic basis of AS and describe the current hypotheses for disease pathogenesis. We synthesize recent experimental research data and clinical studies to support a central role for the type 17/23 immune axis in AS.

IL-22 Binding Protein Promotes the Disease Process in Multiple Sclerosis

Genome-wide association studies have mapped the specific sequence variants that predispose for multiple sclerosis (MS). The pathogenic mechanisms that underlie these associations could be leveraged to develop safer and more effective MS treatments but are still poorly understood. In this article, we study the genetic risk variant rs17066096 and the candidate gene that encodes IL-22 binding protein (IL-22BP), an antagonist molecule of the cytokine IL-22. We show that monocytes from carriers of the risk genotype of rs17066096 express more IL-22BP in vitro and cerebrospinal fluid levels of IL-22BP correlate with MS lesion load on magnetic resonance imaging. We confirm the pathogenicity of IL-22BP in both rat and mouse models of MS and go on to suggest a pathogenic mechanism involving lack of IL-22-mediated inhibition of T cell-derived IFN-γ expression. Our results demonstrate a pathogenic role of IL-22BP in three species with a potential mechanism of action involving T cell polarization, suggesting a therapeutic potential of IL-22 in the context of MS.

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.

Expansion of IL-23 receptor bearing TNFR2+ T cells is associated with molecular resistance to anti-TNF therapy in Crohn's disease

OBJECTIVE

Anti-tumour necrosis factor (TNF) antibodies are successfully used for treatment of Crohn's disease. Nevertheless, approximately 40% of patients display failure to anti-TNF therapy. Here, we characterised molecular mechanisms that are associated with endoscopic resistance to anti-TNF therapy.

DESIGN

Mucosal and blood cells were isolated from patients with Crohn's disease prior and during anti-TNF therapy. Cytokine profiles, cell surface markers, signalling proteins and cell apoptosis were assessed by microarray, immunohistochemistry, qPCR, ELISA, whole organ cultures and FACS.

RESULTS

Responders to anti-TNF therapy displayed a significantly higher expression of TNF receptor 2 (TNFR2) but not IL23R on T cells than non-responders prior to anti-TNF therapy. During anti-TNF therapy, there was a significant upregulation of mucosal IL-23p19, IL23R and IL-17A in anti-TNF non-responders but not in responders. Apoptosis-resistant TNFR2+IL23R+ T cells were significantly expanded in anti-TNF non-responders compared with responders, expressed the gut tropic integrins α4β7, and exhibited increased expression of IFN-γ, T-bet, IL-17A and RORγt compared with TNFR2+IL23R- cells, indicating a mixed Th1/Th17-like phenotype. Intestinal TNFR2+IL23R+ T cells were activated by IL-23 derived from CD14+ macrophages, which were significantly more present in non-responders prior to anti-TNF treatment. Administration of IL-23 to anti-TNF-treated mucosal organ cultures led to the expansion of CD4+IL23R+TNFR2+ lymphocytes. Functional studies demonstrated that anti-TNF-induced apoptosis in mucosal T cells is abrogated by IL-23.

CONCLUSIONS

Expansion of apoptosis-resistant intestinal TNFR2+IL23R+ T cells is associated with resistance to anti-TNF therapy in Crohn's disease. These findings identify IL-23 as a suitable molecular target in patients with Crohn's disease refractory to anti-TNF therapy.

IL-12, IL-23 and IL-17 in IBD: immunobiology and therapeutic targeting

IL-12 and IL-23 are closely related cytokines with important roles in the regulation of tissue inflammation. Converging evidence from studies in mice, human observational studies and population genetics supports the importance of these cytokines in the regulation of mucosal inflammation in the gut in particular. Ustekinumab, a therapeutic antibody targeting both cytokines is now widely licensed for the treatment of Crohn's disease, including in Europe, the USA, Canada and Japan, whilst agents targeting IL-23 specifically are in late-phase clinical trials. We review the emerging understanding of the biology of IL-12 and IL-23, as well as that of their major downstream cytokines, including IL-17. In particular, we discuss how their biology has influenced the development of clinical trials and therapeutic strategies in IBD, as well as how findings from clinical trials, at times surprising, have in turn refocused our understanding of the underlying biology.

Prioritizing Crohn's disease genes by integrating association signals with gene expression implicates monocyte subsets

Genome-wide association studies have identified ~170 loci associated with Crohn's disease (CD) and defining which genes drive these association signals is a major challenge. The primary aim of this study was to define which CD locus genes are most likely to be disease related. We developed a gene prioritization regression model (GPRM) by integrating complementary mRNA expression datasets, including bulk RNA-Seq from the terminal ileum of 302 newly diagnosed, untreated CD patients and controls, and in stimulated monocytes. Transcriptome-wide association and co-expression network analyses were performed on the ileal RNA-Seq datasets, identifying 40 genome-wide significant genes. Co-expression network analysis identified a single gene module, which was substantially enriched for CD locus genes and most highly expressed in monocytes. By including expression-based and epigenetic information, we refined likely CD genes to 2.5 prioritized genes per locus from an average of 7.8 total genes. We validated our model structure using cross-validation and our prioritization results by protein-association network analyses, which demonstrated significantly higher CD gene interactions for prioritized compared with non-prioritized genes. Although individual datasets cannot convey all of the information relevant to a disease, combining data from multiple relevant expression-based datasets improves prediction of disease genes and helps to further understanding of disease pathogenesis.

Genetics in ankylosing spondylitis - Current state of the art and translation into clinical outcomes

Ankylosing spondylitis (AS) is the prototypic form of axial spondyloarthritis (axSpA). It is highly heritable, with studies conducted in twins and in unrelated cases and controls showing that the heritability for AS is much higher than those for inflammatory bowel disease or rheumatoid arthritis. To date, 116 loci have been identified, contributing to 28% of the genetic variation in the disease. These loci provide important clues into pathogenic pathways in the disease that have led to therapeutic advances such as the repositioning of IL-17 inhibitors in the disease. Much more research is currently required to determine the functional mechanisms by which the genetic associations operate, from which it is likely that novel therapeutic approaches will be developed.

Interleukin 12/interleukin 23 pathway: Biological basis and therapeutic effect in patients with Crohn's disease

Considering that both innate and adaptive immune responses are involved in the pathogenesis of Crohn’s disease (CD), novel therapeutic options have significantly been developed. Biological agents represent an important addition to the conventional treatments for immuno-inflammatory conditions, acting as antagonists of adhesion molecules or various inflammatory cytokines. The interleukin 12 (IL-12)/IL-23 common pathway has been found to play a determinant role in the induction of inflammation in adaptive immune responses. In particular, IL-23 promotes the differentiation of naïve T helper cells into Th17 phenotype with the concomitant secretion of several inflammatory cytokines such as IL-17 and IL-22, whereas IL-12 induces the Th1 polarization and production of critical cytokines such as interferon-γ and tumor necrosis factor. Nowadays, there is increased interest regarding the role of IL-23 as a therapeutic target of CD through the blockage of IL-23 mediated pathways. In this editorial, we focus on the role of IL-12/IL-23 pathway in the regulation of mucosal immunity and in the induction and maintenance of chronic inflammation. In parallel, we critically discuss the available data regarding the therapeutic effect of the IL-12/IL-23 inhibitors and especially of ustekinumab, a human monoclonal antibody which has been recently approved by the United States Food and Drug Administration for the management of moderate-to-severe CD and its potential to be used as first-line therapy in everyday clinical practice.

Reduced monocyte and macrophage TNFSF15/TL1A expression is associated with susceptibility to inflammatory bowel disease

Chronic inflammation in inflammatory bowel disease (IBD) results from a breakdown of intestinal immune homeostasis and compromise of the intestinal barrier. Genome-wide association studies have identified over 200 genetic loci associated with risk for IBD, but the functional mechanisms of most of these genetic variants remain unknown. Polymorphisms at the TNFSF15 locus, which encodes the TNF superfamily cytokine commonly known as TL1A, are associated with susceptibility to IBD in multiple ethnic groups. In a wide variety of murine models of inflammation including models of IBD, TNFSF15 promotes immunopathology by signaling through its receptor DR3. Such evidence has led to the hypothesis that expression of this lymphocyte costimulatory cytokine increases risk for IBD. In contrast, here we show that the IBD-risk haplotype at TNFSF15 is associated with decreased expression of the gene by peripheral blood monocytes in both healthy volunteers and IBD patients. This association persists under various stimulation conditions at both the RNA and protein levels and is maintained after macrophage differentiation. Utilizing a "recall-by-genotype" bioresource for allele-specific expression measurements in a functional fine-mapping assay, we localize the polymorphism controlling TNFSF15 expression to the regulatory region upstream of the gene. Through a T cell costimulation assay, we demonstrate that genetically regulated TNFSF15 has functional relevance. These findings indicate that genetically enhanced expression of TNFSF15 in specific cell types may confer protection against the development of IBD.

Involvement of the IL23/Th17 Pathway in the Pathogenesis of Tunisian Pemphigus Foliaceus

Pemphigus foliaceus (PF) is a rare autoimmune skin disease caused by anti-Dsg1 pathogenic autoantibodies. It is considered as a Th2-mediated disease. Likewise, Th17 cells were recently described in the pathogenesis of the disease but their role is still unclear. We aimed to unravel the eventual implication of the IL23/Th17 pathway in the development of PF. A case-control study was conducted on 115 PF patients and 201 healthy controls using PCR-RFLP and AS-PCR methods. SNPs in IL23R, RORγt, IL17A, IL17F, IL17AR, TNFa, and STAT3 genes were genotyped. mRNA expression of IL23R and RORγt was evaluated using Q-PCR. The frequency of circulating Th17 cells was analyzed by flow cytometry. Genetic associations between IL23R>rs11209026, IL17A>rs3748067, IL17F>rs763780, and TNFa>rs1800629 and the susceptibility to PF were reported. Moreover, we revealed a significant increased frequency of circulating CD4⁺IL17⁺ cells as well as higher mRNA levels of RORγt and IL23R in PBMCs of patients. However, no significant increase of RORγt and IL23R mRNA expression was observed in lesional skin biopsies. In spite of the little size of specimens, our results provide converging arguments for the contribution of the IL23/Th17 pathway in the pathogenesis of PF.

Immunotherapy in inflammatory bowel disease: Novel and emerging treatments

Inflammatory bowel disease (IBD) is a chronic disabling inflammatory process that affects young individuals, with growing incidence. The etiopathogenesis of IBD remains poorly understood. A combination of genetic and environmental factors triggers an inadequate immune response against the commensal intestinal flora in IBD patients. Thus, a better understanding of the immunological mechanisms involved in IBD pathogenesis is central to the development of new therapeutic options.

Current pharmacological treatments used in clinical practice like thiopurines or anti-TNF are effective but can produce significant side effects and their efficacy may diminish over time. In fact, up to one third of the patients do not have a satisfactory response to these therapies. Consequently, the search for new therapeutic strategies targeting alternative immunological pathways has intensified. Several new oral and parenteral substances are in the pipeline for IBD.

In this review we discuss novel therapies targeting alternative pro-inflammatory pathways like IL-12/23 axis, IL-6 pathway or Janus Kinase inhibitors; as well as others modulating anti-inflammatory signalling pathways like transforming growth factor-β1 (TGF-β1). We also highlight new emerging therapies targeting the adhesion and migration of leukocytes into the inflamed intestinal mucosa by blocking selectively different subunits of α₄β₇ integrins or binding alternative adhesion molecules like MAdCAM-1. Drugs reducing the circulating lymphocytes by sequestering them in secondary lymphoid organs (sphingosine-1-phosphate (S1P) receptor modulators) are also discussed. Finally, the latest advances in cell therapies using mesenchymal stem cells or engineered T regs are reviewed. In addition, we provide an update on the current status in clinical trials of these new immune-regulating therapies that open a new era in the treatment of IBD.

Genetic polymorphism in ATG16L1 gene is associated with adalimumab use in inflammatory bowel disease

Background

The role of single nucleotide polymorphisms (SNPs) associated with inflammatory bowel disease (IBD) is gaining interest. With the advent of novel therapies, personalized treatment in IBD is a future goal. We wondered whether IBD-associated SNPs are able to predict response to anti-TNFα treatment.

Methods

Data on treatment use and primary response, loss of response and side effects to anti-TNFα treatments were retrieved for 570 IBD patients. rs13361189 (IRGM), rs10210302 (ATG16L1), rs2066844, rs2066845, rs2066847 (NOD2), rs35873774 (XBP1), rs11175593 (LRRK2), rs11465804 (IL23R), rs2301436 (CCR6), rs744166 (STAT3) and rs4821544 (NCF4) SNP status were determined.

Results

No associations were found between genetic variants of the LRRK2, CCR6, IL23R and NCF4 genes and response to anti-TNFα. For NOD2 and XBP1 associations were found, however, these associations were not strong enough to survive multiple testing corrections. Strikingly, patients carrying the ATG16L1 T300A variant were more likely to be treated with adalimumab, even after correction for disease phenotype, disease behavior and age (p = 0.004, OR 2.8, CI 1.6–5.0).

Conclusions

Genetic polymorphisms in the known IBD-associated gene ATG16L1 correlate with requirement of treatment, suggesting a different IBD disease phenotype in these patients. Further investigation will need to elucidate the implications of these findings and identify the underlying disease characteristics.

Electronic supplementary material

The online version of this article (10.1186/s12967-017-1355-9) contains supplementary material, which is available to authorized users.

Recipe for IBD: can we use food to control inflammatory bowel disease?

The mucosal immune system and the microbiota in the intestinal tract have recently been shown to play a key role in the pathogenesis of inflammatory bowel disease (IBD). Both of these can be influenced by food. Thus, we propose dietary intervention as a therapeutic option for IBD. In this review, we discuss the interaction of the intestinal mucosal immune system and the intestinal microbiota in the context of IBD. In addition, we discuss the impact of food components on immune responses in IBD. Finally, we address the current evidence of how this interaction (i.e., immune system-microbiota) can be modulated by food components, pre/probiotics, and fecal microbiota transplantation (FMT) and how these approaches can support intestinal homeostasis. By gathering the vast amount of literature available on the impact of food on IBD, we aim to distinguish between scientifically sound data and theories, which have not been included in this review.

Mechanisms of Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including Crohn disease and ulcerative colitis, is characterized by chronic intestinal inflammation due to a complex interaction of genetic determinants, disruption of mucosal barriers, aberrant inflammatory signals, loss of tolerance, and environmental triggers. Importantly, the incidence of pediatric IBD is rising, particularly in children younger than 10 years. In this review, we discuss the clinical presentation of these patients and highlight environmental exposures that may affect disease risk, particularly among people with a background genetic risk. With regard to both children and adults, we review advancements in understanding the intestinal epithelium, the mucosal immune system, and the resident microbiota, describing how dysfunction at any level can lead to diseases like IBD. We conclude with future directions for applying advances in IBD genetics to better understand pathogenesis and develop therapeutics targeting key pathogenic nodes.

Lessons Learned From Trials Targeting Cytokine Pathways in Patients With Inflammatory Bowel Diseases

Insights into the pathogenesis of inflammatory bowel diseases (IBDs) have provided important information for the development of therapeutics. Levels of interleukin 23 (IL23) and T-helper (Th) 17 cell pathway molecules are increased in inflamed intestinal tissues of patients with IBD. Loss-of-function variants of the IL23-receptor gene (IL23R) protect against IBD, and, in animals, blocking IL23 reduces the severity of colitis. These findings indicated that the IL23 and Th17 cell pathways might be promising targets for the treatment of IBD. Clinical trials have investigated the effects of agents designed to target distinct levels of the IL23 and Th17 cell pathways, and the results are providing insights into IBD pathogenesis and additional strategies for modulating these pathways. Strategies to reduce levels of proinflammatory cytokines more broadly and increase anti-inflammatory mechanisms also are emerging for the treatment of IBD. The results from trials targeting these immune system pathways have provided important lessons for future trials. Findings indicate the importance of improving approaches to integrate patient features and biomarkers of response with selection of therapeutics.

The genetic background of inflammatory bowel disease: from correlation to causality

Recent studies have greatly improved our insight into the genetic background of inflammatory bowel disease (IBD). New high-throughput technologies and large-scale international collaborations have contributed to the identification of 200 independent genetic risk loci for IBD. However, in most of these loci, it is unclear which gene conveys the risk for IBD. More importantly, it is unclear which variant within or near the gene is causal to the disease. Using targeted GWAS, imputation, resequencing of risk loci, and in silico fine-mapping of densely typed loci, several causal variants have been identified in IBD risk genes, and various pathological pathways have been uncovered. Current research in the field of IBD focuses on the effect of these causal variants on gene expression and protein function. However, more elements than only the genome must be taken into account to disentangle the multifactorial pathology of IBD. The genetic risk loci identified to date only explain a small part of genetic variance in disease risk. Currently, large multi-omics studies are incorporating factors ranging from the gut microbiome to the environment. In this review, we present the progress that has been made in IBD genetic research and stress the importance of studying causality to increase our understanding of the pathogenesis of IBD. We highlight important causal genetic variants in the candidate genes NOD2, ATG16L1, IRGM, IL23R, CARD9, RNF186, and PRDM1. We describe their downstream effects on protein function and their direct effects on the gut immune system. Furthermore, we discuss the future role of genetics in unravelling disease mechanisms in IBD. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Genetic variation in IBD: progress, clues to pathogenesis and possible clinical utility

Epidemiological and clinical studies have suggested that the pathogenesis of inflammatory bowel disease (IBD) is strongly influenced by genetic predisposition. Beyond the limitations of linkage analysis, multiple genome-wide association studies, their meta-analyses, and targeted genotyping array techniques have broadened our understanding of the genetic architecture of IBD. Currently, over 200 single nucleotide polymorphisms are known to be associated with susceptibility to IBD and through functional analysis of genes and loci, a substantial proportion of pathophysiologic mechanisms have been revealed. However, because only a modest fraction of predicted heritability can be explained by known genes/loci, additional strategies are needed including the identification of rare variants with large effect sizes to help explain the missing heritability. Considerable progress is also being made on applying outcomes of genetic research in diagnostics, classification, prognostics, and the development of new therapeutics of IBD.

Elevated IL-23R Expression and Foxp3+Rorgt+ Cells in Intestinal Mucosa During Acute and Chronic Colitis

Background

IL-23/IL-23R signaling plays a pivotal role during the course of inflammatory bowel diseases (IBD). However, the underlying mechanisms are poorly characterized. Foxp3⁺ regulatory T cells are critical in the maintenance of gut immune homeostasis and therefore are important in preventing the development of IBD. This study was performed to clarify the association between IL-23/IL-23R signaling and Foxp3⁺ regulatory T cells in colitis.

Material/Methods

Acute and chronic mouse colitis models were established by administering mice DSS in drinking water. IL-23R, IL-23, IL-I7, and IFN-γ expression level, as well as regulatory T cell, Th17-, and Th1-related transcription factors Foxp3, RORγt, and T-bet were assayed by real-time PCR. The frequency of Foxp3⁺ RORγt⁺ cells in a Foxp3⁺ cell population in colon mucosa during acute and chronic colitis was evaluated through flow cytometry. The signaling pathway mediated by IL-23R in the colon mucosa from acute colitis mice and chronic colitis mice was monitored by Western blot analysis.

Results

We detected elevated IL-23R, IL-23, and IFN-γ expression in colon mucosa during acute and chronic colitis and found increased IL-17 in acute colitis mice. Transcription factors Foxp3 and T-bet were elevated in colon mucosa during acute and chronic colitis. Phosphorylation of Stat3 was greatly enhanced, indicating the activation of IL-23R function in colitis mice. The percentage of Foxp3⁺ T cells in acute and chronic colitis mice was comparable to control mice, but there was a 2-fold increase of Foxp3⁺ RORγt⁺ cells among the Foxp3⁺ cell population in acute and chronic colitis mice compared to control mice.

Conclusions

These findings indicate that the induction of Foxp3⁺ RORγt⁺ T cells could be enhanced during inflammation in the intestine where IL-23R expression is greatly induced. Our study highlights the importance of IL-23R expression level and the instability of Foxp3⁺ regulatory T cells in the development of inflammatory bowel diseases.

Defining the functional binding sites of interleukin 12 receptor β1 and interleukin 23 receptor to Janus kinases

Stimulation of cells with the IL-12–type cytokine IL-12 or IL-23 results in activation of receptor-associated Janus kinases (Jak) and phosphorylation of STAT proteins in target cells. Functional association of IL 12Rβ1 with tyrosine kinase 2 and IL-23R with Jak2 is mandatory for IL-12 and/or IL-23 signaling.

The interleukin (IL)-12–type cytokines IL-12 and IL-23 are involved in T-helper (Th) 1 and Th17 immunity, respectively. They share the IL-12 receptor β1 (IL-12Rβ1) as one component of their receptor signaling complexes, with IL-12Rβ2 as second receptor for IL-12 and IL-23R for IL-23 signal transduction. Stimulation with IL-12 and IL-23 results in activation of receptor-associated Janus kinases (Jak) and phosphorylation of STAT proteins in target cells. The Janus kinase tyrosine kinase (Tyk) 2 associates with IL-12Rβ1, whereas Jak2 binds to IL-23R and also to IL-12Rβ2. Receptor association of Jak2 is mediated by Box1 and Box2 motifs located within the intracellular domain of the receptor chains. Here we define the Box1 and Box2 motifs in IL-12Rβ1 and an unusual Jak2-binding site in IL-23R by the use of deletion and site-directed mutagenesis. Our data show that nonfunctional box motifs abolish IL-12– and IL-23–induced STAT3 phosphorylation and cytokine-dependent proliferation of Ba/F3 cells. Coimmunoprecipitation of Tyk2 by IL-12Rβ1 and Jak2 by IL‑23R supported these findings. In addition, our data demonstrate that association of Jak2 with IL-23R is mandatory for IL-12 and/or IL-23 signaling, whereas Tyk2 seems to be dispensable.

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.

IL23R (Interleukin 23 Receptor) Variants Protective against Inflammatory Bowel Diseases (IBD) Display Loss of Function due to Impaired Protein Stability and Intracellular Trafficking

Genome-wide association studies as well as murine models have shown that the interleukin 23 receptor (IL23R) pathway plays a pivotal role in chronic inflammatory diseases such as Crohn disease (CD), ulcerative colitis, psoriasis, and type 1 diabetes. Genome-wide association studies and targeted re-sequencing studies have revealed the presence of multiple potentially causal variants of the IL23R. Specifically the G149R, V362I, and R381Q IL23Rα chain variants are linked to protection against the development of Crohn disease and ulcerative colitis in humans. Moreover, the exact mechanism of action of these receptor variants has not been elucidated. We show that all three of these IL23Rα variants cause a reduction in IL23 receptor activation-mediated phosphorylation of the signal-transducing activator of transcription 3 (STAT3) and phosphorylation of signal transducing activator of transcription 4 (STAT4). The reduction in signaling is due to lower levels of cell surface receptor expression. For G149R, the receptor retention in the endoplasmic reticulum is due to an impairment of receptor maturation, whereas the R381Q and V362I variants have reduced protein stability. Finally, we demonstrate that the endogenous expression of IL23Rα protein from V362I and R381Q variants in human lymphoblastoid cell lines exhibited lower expression levels relative to susceptibility alleles. Our results suggest a convergent cause of IL23Rα variant protection against chronic inflammatory disease.

Association of Interleukin-23 receptor gene polymorphisms with susceptibility to Crohn's disease: A meta-analysis

Studies investigating the association between Interleukin-23 receptor (IL-23R) gene polymorphisms and Crohn’s disease (CD) report conflicting results. Thus, a meta-analysis was carried out to assess the association between the IL-23R polymorphisms and CD. A systematic literature search was conducted to identify all relevant studies. Pooled odds ratio (ORs) with 95% confidence interval (CIs) was used to estimate the strength of association. Finally, a total of 60 case-control studies in 56 articles, involving 22,820 CD patients and 27,401 healthy controls, were included in the meta-analysis. Overall, a significant association was found between all CD and the rs7517847 polymorphism (OR = 0.699, 95% CI = 0.659 ~ 0.741, P < 0.001). Meta-analysis of the rs11209026, rs1343151, rs10489629 and rs11465804 polymorphisms indicated the same pattern as for rs7517847. Meta-analysis showed an association between the rs10889677A allele and CD (OR = 1.393, 95% CI = 1.328 ~ 1.461, P < 0.001). Similarly, meta-analysis of the rs2201840, rs1004819, rs1495965 and rs11209032 polymorphisms revealed the same pattern as that shown by meta-analysis of rs10889677. Stratification by ethnicity revealed that IL-23R gene polymorphisms were associated with CD in the Caucasian group, but not in Asians. In summary, the meta-analysis suggests a significant association between IL-23R polymorphisms and CD, especially in Caucasians.

Genetics of Inflammatory Bowel Diseases

In this review, we provide an update on genome-wide association studies (GWAS) in inflammatory bowel disease (IBD). In addition, we summarize progress in defining the functional consequences of associated alleles for coding and noncoding genetic variation. In the small minority of loci where major association signals correspond to nonsynonymous variation, we summarize studies defining their functional effects and implications for therapeutic targeting. Importantly, the large majority of GWAS-associated loci involve noncoding variation, many of which modulate levels of gene expression. Recent expression quantitative trait loci (eQTL) studies have established that the expression of most human genes is regulated by noncoding genetic variations. Significant advances in defining the epigenetic landscape have demonstrated that IBD GWAS signals are highly enriched within cell-specific active enhancer marks. Studies in European ancestry populations have dominated the landscape of IBD genetics studies, but increasingly, studies in Asian and African-American populations are being reported. Common variation accounts for only a modest fraction of the predicted heritability and the role of rare genetic variation of higher effects (ie, odds ratios markedly deviating from 1) is increasingly being identified through sequencing efforts. These sequencing studies have been particularly productive in more severe very early onset cases. A major challenge in IBD genetics will be harnessing the vast array of genetic discovery for clinical utility through emerging precision medical initiatives. In this article, we discuss the rapidly evolving area of direct-to-consumer genetic testing and the current utility of clinical exome sequencing, especially in very early onset, severe IBD cases. We summarize recent progress in the pharmacogenetics of IBD with respect to partitioning patient responses to anti-TNF and thiopurine therapies. Highly collaborative studies across research centers and across subspecialties and disciplines will be required to fully realize the promise of genetic discovery in IBD.

Low-Frequency IL23R Coding Variant Associated with Crohn's Disease Susceptibility in Japanese Subjects Identified by Personal Genomics Analysis

BACKGROUND

The common disease-common variant hypothesis is insufficient to explain the complexities of Crohn's disease (CD) genetics; therefore, rare variants are expected to be important in the disease. We explored rare variants associated with susceptibility to CD in Japanese individuals by personal genomic analysis.

METHODS

Two-step analyses were performed. The first step was a trio analysis with whole-exome sequence (WES) analysis and the second was a follow-up case-control association study. The WES analysis pipeline comprised Burrows-Wheeler Aligner, Picard, Genome Analysis Toolkit, and SAMTOOLS. Single nucleotide variants (SNVs)/indels were annotated and filtered by using programs implemented in ANNOVAR in combination with identity-by-descent (IBD), subsequently were subjected to the linkage based, and de novo based strategies. Finally, we conducted an association study that included 176 unrelated subjects with CD and 358 healthy control subjects.

RESULTS

In family members, 234,067-297,523 SNVs/indels were detected and they were educed to 106-146 by annotation based filtering. Fifty-four CD variants common to both individuals of the affected sib pair were identified. The linkage based strategy detected five candidate variants whereas the de novo based strategy identified no variants. Consequently, five candidates were analyzed in the case-control association study. CD showed a significant association with one variant in exon 4 of IL23R, G149R [rs76418789, P = 3.9E-5, odds ratio (OR) 0.21, 95% confidence interval (CI) 0.09-0.47 for the dominant model (AA + AG versus GG), and P = 7.3E-5, OR 0.21, 95% CI 0.10-0.48 for AG versus GG, and P = 7.2E-5, OR 0.23, 95% CI 0.10-0.50 for the allele model].

CONCLUSIONS

The present study, using personal genomics analysis of a small CD pedigree, is the first to show that the low-frequency non-synonymous variant of IL23R, rs76418789, protects against CD development in Japanese subjects.

Analysis of the association between IL-23R rs11209026 polymorphism and incidence of atherosclerosis

Th17/IL-23 axis is an important pro-inflammatory pathway in atherosclerosis. IL-23 receptor (IL-23R) pathway has an important role in T-helper cells 17 (Th17) differentiation and survival. We compared normal subjects and patients with atherosclerosis in terms of the R381Q variant of the IL-23R gene as a functional single-nucleotide polymorphism (SNP). This case-control study recruited 200 patients who presented with cardiovascular symptoms to Afshar Hospital, Yazd, Iran. The participants were allocated to five groups based on angiographic results. The severity of the disease was determined according to the numbers of involved vessels. Patients with normal coronary arteries, minimal coronary artery involvement, one involved vessel, two involved vessels and three-vessel disease were allocated to groups I-V, respectively. DNA was extracted from whole blood samples by the salting-out method. Genotyping was performed by polymerase chain reaction followed by restriction fragment length polymorphism assay and multinomial logistic regression for analyses The presence of SNP A>G rs11209026 of IL-23 receptor gene was significantly associated with disease severity (P = 0.008). The frequencies of the heterozygous (AG) genotype in the control group and subjects with minimal involvement, and patients with one-, two-, and three-vessel disease were 22.5%, 12.5%, 10%, 10.24% and 4.8%, respectively. Our results indicated an association between the rs11209026 G>A polymorphism of the IL-23 receptor gene and the risk of atherosclerosis. This genetic variant may in fact cause protection against atherosclerosis progression. However, further studies on gene polymorphism and cell expression are required to clarify the mechanisms involved in the pathogenesis of atherosclerosis.

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.

Heterogeneity of autoimmune diseases: pathophysiologic insights from genetics and implications for new therapies

Recent advances in genome-wide association studies (GWAS) across autoimmune and immune-mediated diseases have augmented our understanding of pathogenic mechanisms underlying these diseases. This has further highlighted their heterogeneous nature, both within and between diseases. Furthermore, varying responses to therapy have also served to underline the importance of this heterogeneity in the manner in which these diseases are diagnosed and treated. Here we discuss our current understanding of the shared pathways of autoimmunity, including the tumor necrosis factor (TNF), major histocompatibility complex (MHC), interleukin 23 receptor (IL23R) and protein tyrosine phosphatase non-receptor type 22 (PTPN22) pathways. In addition, we summarize effective specific therapies tested across major autoimmune diseases, highlighting the insight they have provided into disease mechanisms and their implications for potential future improvements.

IL-12 and IL-23 cytokines: from discovery to targeted therapies for immune-mediated inflammatory diseases

The cytokine interleukin-12 (IL-12) was thought to have a central role in T cell-mediated responses in inflammation for more than a decade after it was first identified. Discovery of the cytokine IL-23, which shares a common p40 subunit with IL-12, prompted efforts to clarify the relative contribution of these two cytokines in immune regulation. Ustekinumab, a therapeutic agent targeting both cytokines, was recently approved to treat psoriasis and psoriatic arthritis, and related agents are in clinical testing for a variety of inflammatory disorders. Here we discuss the therapeutic rationale for targeting these cytokines, the unintended consequences for host defense and tumor surveillance and potential ways in which these therapies can be applied to treat additional immune disorders.

Pouring fuel on the fire: Th17 cells, the environment, and autoimmunity

Cytokines play a critical role in controlling the differentiation of CD4 Th cells into distinct subsets, including IL-17-producing Th17 cells. Unfortunately, the incidence of a number of autoimmune diseases, particularly those in which the IL-23/IL-17 axis has been implicated, has risen in the last several decades, suggesting that environmental factors can promote autoimmunity. Here we review the role of cytokines in Th17 differentiation, particularly the role of IL-23 in promoting the differentiation of a pathogenic subset of Th17 cells that potently induce autoimmune tissue inflammation. Moreover, we highlight emerging data that indicate that environmental factors, including the intestinal microbiota and changes in diet, can alter normal cytokine regulation with potent effects on Th17 differentiation and thus promote autoimmunity, which has strong implications for human disease.