Novel association of the interleukin 2-interleukin 21 region with inflammatory bowel disease

Interleukin-21 as an adjuvant in cancer immunotherapy: Current advances and future directions

Immunotherapy has revolutionized cancer treatment. However, it's well-recognized that a considerable proportion of patients fail to benefit from immunotherapy, and to improve immunotherapy response is clinically urgent. Insufficient immune infiltration and immunosuppressive tumor microenvironments (TME) are main contributors to immunotherapy resistance. Thus sustaining functional self-renewal capacity for immune cells and subverting immune-suppressive signals are potential strategies for boosting the efficacy of immunotherapy. Interleukin-21 (IL-21), a crucial cytokine, which could enhance cytotoxic function of immune cells and reduces immunosuppressive cells enrichment in TME, shows promising orientations as an immunoadjuvant in tumor immunotherapy. This review focuses on IL-21 in cancer treatment, including function and mechanisms of IL-21, preclinical and clinical studies, and future directions for IL-21-assisted therapies.

A New Rat Model of Pouchitis After Proctocolectomy and Ileal Pouch-Anal Anastomosis Using 2,4,6-Trinitrobenzene Sulfonic Acid

BACKGROUND

Pouchitis is a common complication after ileal pouch-anal anastomosis (IPAA) in patients with ulcerative colitis. However, an ideal model remains lacking. Therefore, we aimed to establish an appropriate model resembling human pouchitis.

METHODS

Sprague-Dawley rats were randomly assigned to five groups: TNBS group, DSS group, NS group (following IPAA procedure, administrated with TNBS enema, DSS orally, normal saline enema, respectively), NI group (underwent IPAA), and sham group (underwent switch abdominal surgery). General status, weight change, hematochezia, and fecal scores were recorded. Fecal microbiota were counted under a microscope and analyzed by 16S rRNA gene high-throughput sequencing. Specimens of ileal pouch and small intestine (proximal, mid, distal) were collected to evaluate myeloperoxidase and occludin expression by immunohistochemistry and mRNA expression of pro-inflammatory markers by PCR.

RESULTS

General status, hematochezia, fecal score, and increased mRNA expression of interleukin-6 and TNF-α in the TNBS group were similar to those in the DSS group, whereas the TNBS-induced model displayed a more stable weight change and more serious dysbacteriosis, not only was fecal bacterial diversity reduced, the dominant microbiota was altered. Histopathology scores of the distal small intestine in the TNBS group were lower compared with those in the DSS group (P < 0.05). A significant difference in myeloperoxidase and occludin expression in the small intestine was also detected between the TNBS and DSS groups.

CONCLUSIONS

Our model mimicked the characteristics of human pouchitis and avoided potential side effects in the small intestine, and thus could be employed for further research.

Plasma interleukin-21 levels and genetic variants are associated with susceptibility to rheumatoid arthritis

Background

Rheumatoid Arthritis (RA) is a chronic inflammatory condition characterized by autoantibodies development and an elevated spectrum of pro-inflammatory cytokines. Previous reports highlighted a relationship between IL-21and the pathogenesis of RA. Although elevated IL-21 levels have been reported in RA patients, the association of common IL-21 genetic variants with a predisposition to RA development in the Chinese population lacks.

Materials and methods

Five hundred and fourteen Chinese subjects (healthy controls: 303 and rheumatoid arthritis patients: 211) were enrolled in the study. Clinical data of patients were collected from medical records, and patients were treated as per the guidelines. Common single nucleotide polymorphisms in the IL-21 gene (rs907715, rs2221903, rs2055979 and rs6822844) were genotyped by TaqMan SNPs genotyping method. IL-21 level in plasma of RA patients and healthy subjects was measured by ELISA.

Results

The plasma level of IL-21 was significantly higher in subjects with rheumatoid arthritis relative to healthy controls (p < 0.0001). A positive correlation was observed between IL-21 level and DAS28 score, indicating the association of the cytokine with the worsening of the disease (Spearman r = 0.61, p < 0.0001). The prevalence of AA genotype (rs2055979) was significantly higher in RA subjects than in the controls (p < 0.0001, χ2 = 34.73, OR = 4.34, 95% CI = 2.623 to 7.219). Furthermore, elevated plasma IL-21 was observed in the rs2055979-AA genotype compared to CC type (p < 0.0001).

Conclusion

IL-21 plays a crucial function in rheumatoid arthritis pathogenesis. IL-21 rs2055979 polymorphism is associated with IL-21 plasma levels and is predisposed to RA development in the Chinese population.

Can cinnamon spice down autoimmune diseases?

Autoimmune diseases are one of the dreadful group of human diseases that have always been of keen interest to researchers. Due to complex and broad-spectrum nature, scientists are not yet able to pinpoint the pathogenesis of and delineate effective therapy against this group of diseases. However, it is becoming clear that a decrease in number and function of T regulatory cells (Treg), an increase in autoreactive Th1/Th17 cells and associated immunomodulation and inflammation participate in the pathogenesis of many autoimmune diseases. Cinnamon (Cinnamonum verum or Cinnamonum cassia) is a widely used natural spice and flavoring ingredient and its metabolite sodium benzoate (NaB) is a food-additive and FDA-approved drug against nonketotic hyperglycinemia (NKH) and urea cycle disorders (UCD). Recent studies indicate that cinnamon either in powder or extract form and NaB are capable of modulating different autoimmune pathways as well as protecting animals from different autoimmune disorders. Here, we have made an honest attempt to delineate such pieces of evidence with available anti-autoimmune mechanisms and analyze whether cinnamon supplements could be used to control the fury of autoimmune disorders.

Association of rs6822844 within the KIAA1109/TENR/IL2/IL21 locus with rheumatoid arthritis in the Algerian population

Increasing evidence suggests that the rs6822844, within KIAA1109/TENR/IL2/IL21 gene cluster on 4q27, is strongly associated with rheumatoid arthritis (RA) in the Caucasian population. The aim of this study is to investigate the possible association between the SNP rs6822844 and susceptibility to RA in the Algerian Maghreb population, and to explore the association with the clinical and immunological features of RA. The polymorphism rs6822844 was genotyped in 323 RA patients and 323 healthy individuals using the TaqMan assay. A strong association of IL2/IL21 with RA susceptibility was detected in the Algerian population [odds ratio (OR) = 2.57 (95% confidence interval (CI) 1.74-3.83), P = 10(-4) ]. Our results revealed that IL2/IL21 predisposed to disease development in both autoantibody positive and negative disease. Meanwhile, the association was stronger in RA patients with anti-cyclic citrullinated peptides (ACPA) positive than those with ACPA negative [OR = 2.30 (95% CI 1.53-3.51), P = 10(-4) and OR = 1.98 (95% CI 1.01-4.22), P = 0.037, respectively]. Moreover, our findings showed a moderate association of the rs6822844 polymorphism with disease activity (P = 0.014). This study indicates for the first time that there is a strong association between IL2/IL21 rs6822844 variant and susceptibility to RA in the Algerian population, and that this association was independent from the autoantibodies status of RA patients.

A candidate gene approach of the calcineurin pathway to identify variants associated with clinical outcomes in renal transplantation

AIM

To investigate the potential influence of variants in genes involved in the calcineurin pathway on the efficacy and toxicity of calcineurin inhibitors in renal transplantation.

MATERIALS & METHODS

Twenty-three polymorphisms in thirteen genes were tested in 381 renal transplant recipients receiving ciclosporin (n = 221) or tacrolimus (n = 160) and mycophenolate mofetil. Data were collected prospectively over the first year post-transplantation.

RESULTS

Multivariate survival analyses revealed no genetic associations with biopsy proven acute graft rejection and serious infections. Donor-recipient Cytomegalovirus mismatch was the only variable associated with serious infection.

CONCLUSION

This large exploratory study casts doubts on the potential interest of genetic biomarkers related to CNI pharmacodynamics but associations with other phenotypes in transplantation deserve further studies.

Cytokines in the Germinal Center Niche

Cytokines are small, secreted, glycoproteins that specifically affect the interactions and communications between cells. Cytokines are produced transiently and locally, acting in a paracrine or autocrine manner, and they are extremely potent, ligating high affinity cell surface receptors to elicit changes in gene expression and protein synthesis in the responding cell. Cytokines produced during the differentiation of T follicular helper (Tfh) cells and B cells within the germinal center (GC) niche play an important role in ensuring that the humoral immune response is robust, whilst retaining flexibility, during the generation of affinity matured antibodies. Cytokines produced by B cells, antigen presenting cells and stromal cells are important for the differentiation of Tfh cells and Tfh cell produced cytokines act both in an autocrine fashion to firm Tfh cell differentiation and in a paracrine fashion to support the differentiation of memory B cells and plasma cells. In this review, we discuss the role of cytokines during the GC reaction with a particular focus on the influence of cytokines on Tfh cells.

Estimating the Ages of Selection Signals from Different Epochs in Human History

Genetic variation harbors signatures of natural selection driven by selective pressures that are often unknown. Estimating the ages of selection signals may allow reconstructing the history of environmental changes that shaped human phenotypes and diseases. We have developed an approximate Bayesian computation (ABC) approach to estimate allele ages under a model of selection on new mutations and under demographic models appropriate for human populations. We have applied it to two resequencing data sets: An ultra-high depth data set from a relatively small sample of unrelated individuals and a lower depth data set in a larger sample with transmission information. In addition to evaluating the accuracy of our method based on simulations, for each SNP, we assessed the consistency between the posterior probabilities estimated by the ABC approach and the ancient DNA record, finding good agreement between the two types of data and methods. Applying this ABC approach to data for eight single nucleotide polymorphisms (SNPs), we were able to rule out an onset of selection prior to the dispersal out-of-Africa for three of them and more recent than the spread of agriculture for an additional three SNPs.

Targeting the binding interface on a shared receptor subunit of a cytokine family enables the inhibition of multiple member cytokines with selectable target spectrum

The common γ molecule (γc) is a shared signaling receptor subunit used by six γc-cytokines. These cytokines play crucial roles in the differentiation of the mature immune system and are involved in many human diseases. Moreover, recent studies suggest that multiple γc-cytokines are pathogenically involved in a single disease, thus making the shared γc-molecule a logical target for therapeutic intervention. However, the current therapeutic strategies seem to lack options to treat such cases, partly because of the lack of appropriate neutralizing antibodies recognizing the γc and, more importantly, because of the inherent and practical limitations in the use of monoclonal antibodies. By targeting the binding interface of the γc and cytokines, we successfully designed peptides that not only inhibit multiple γc-cytokines but with a selectable target spectrum. Notably, the lead peptide inhibited three γc-cytokines without affecting the other three or non-γc-cytokines. Biological and mutational analyses of our peptide provide new insights to our current understanding on the structural aspect of the binding of γc-cytokines the γc-molecule. Furthermore, we provide evidence that our peptide, when conjugated to polyethylene glycol to gain stability in vivo, efficiently blocks the action of one of the target cytokines in animal models. Collectively, our technology can be expanded to target various combinations of γc-cytokines and thereby will provide a novel strategy to the current anti-cytokine therapies against immune, inflammatory, and malignant diseases.

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.

Interleukins and interleukin receptors in rheumatoid arthritis: Research, diagnostics and clinical implications

Rheumatoid arthritis (RA) is an autoimmune disease, resulting in a chronic, systemic inflammatory disorder. It may affect many tissues and organs, but it primarily affects the flexible joints. In clinical practice patient care generates many questions about diagnosis, prognosis, and treatment. It is challenging for health care specialists to keep up to date with the medical literature. This review summarizes the pathogenesis, the polymorphisms of interleukin and interleukin genes and the standard available and possible future immunologic targets for RA treatment. The identification of disease-associated interleukin and interleukin receptor genes can provide precious insight into the genetic variations prior to disease onset in order to identify the pathways important for RA pathogenesis. The knowledge of the complex genetic background may prove useful for developing novel therapies and making personalized medicine based on the individual’s genetics.

Expression of IL-2, IL-17 and TNF-alpha in patients with Crohn's disease treated with anti-TNF antibodies

BACKGROUND

The T cell cytokine IL-17 and the Th-17 pathway appear to have a role in the pathogenesis of inflammatory bowel diseases. IL-2 is a potent stimulator of lymphocyte proliferation and IL2/IL21 receptor polymorphisms have recently been associated with susceptibility to IBD.

AIMS

To evaluate the expression of IL-17, IL-2 and TNFα in Crohn's disease (CD) patients with and without anti-TNFs.

METHODS

Cytokine expression was evaluated by ELISA and intracellular staining of CD4(+) T-cells from the peripheral blood and lamina propria of CD patients and of non-IBD controls. The results were stratified by disease activity and anti-TNF treatment.

RESULTS

IL2 expression was significantly elevated in CD patients not treated with anti-TNFs in comparison to healthy controls (19.6% vs. 33.3%, P=0.03) and CD patients treated with anti-TNFs (20.4% vs. 33.3%, P=0.02), and similar in infliximab-treated patients and controls. IL17 expression was similar in CD patients and controls, and was not affected by anti-TNF therapy. TNFα expression in patients with active CD was increased compared to controls (35.5% vs 25.7%, P<0.005), and was significantly decreased in anti-TNF treated patients in comparison to CD patients without anti-TNFs (39.6% vs 26.2%, P=0.01).

CONCLUSIONS

Expression of IL2 was significantly decreased in anti-TNF-treated CD patients in comparison to non-treated CD patients and controls. This novel finding may indicate a further mechanism of anti-TNF therapy in CD. Expression of IL17 was not influenced by presence of CD or anti-TNF therapy, which may partly explain the failure of recent clinical trials investigating anti-IL17 therapy in CD.

Identification of inflammatory bowel disease-related proteins using a reverse k-nearest neighbor search

Inflammatory bowel disease (IBD) is a chronic disease whose incidence and prevalence increase every year; however, the pathogenesis of IBD is still unclear. Thus, identifying IBD-related proteins is important for understanding its complex disease mechanism. Here, we propose a new and simple network-based approach using a reverse k-nearest neighbor ( R k NN ) search to identify novel IBD-related proteins. Protein–protein interactions (PPI) and Genome-Wide Association Studies (GWAS) were used in this study. After constructing the PPI network, the R k NN search was applied to all of the proteins to identify sets of influenced proteins among their k-nearest neighbors ( R k NNs ). An observed protein whose influenced proteins were mostly known IBD-related proteins was statistically identified as a novel IBD-related protein. Our method outperformed a random aspect, k NN search, and centrality measures based on the network topology. A total of 39 proteins were identified as IBD-related proteins. Of these proteins, 71% were reported at least once in the literature as related to IBD. Additionally, these proteins were found over-represented in the IBD pathway and enriched in importantly functional pathways in IBD. In conclusion, the R k NN search with the statistical enrichment test is a great tool to identify IBD-related proteins to better understand its complex disease mechanism.

Association of IL-21 polymorphisms (rs907715, rs2221903) with susceptibility to multiple autoimmune diseases: a meta-analysis

OBJECTIVES

Previous published data indicated that interleukin-21 (IL-21) gene polymorphisms were shown to associate with multiple autoimmune diseases (ADs), but the results remain inconclusive. The aim of this study was to perform a meta-analysis to assess the overall association between IL-21 gene polymorphisms (rs907715, rs2221903) and multiple ADs.

METHODS

All eligible case-control studies were searched in the PubMed and Embase database. A meta-analysis was conducted on the association between the IL-21 gene variants and ADs using: (1) allelic contrast, (2) homozygote contrast, (3) the recessive model, and (4) the dominant model.

RESULTS

A total of 12 relevant studies including 10,535 cases and 19,356 controls were enrolled in this meta-analysis. A significant association between IL-21 rs907715 gene polymorphism and AD was found under the allelic (OR: 1.102, 95% CI: 1.057-1.149, p = 0.000), homozygous (OR: 1.220, 95% CI: 1.089-1.368, p = 0.001), dominant (OR: 1.160, 95% CI: 1.027-1.309, p = 0.017), and recessive genetic model (OR: 1.119, 95% CI: 1.055-1.187, p = 0.000) among Caucasian populations. However, there was no significant association between IL-21 rs2221903 polymorphism and AD in different genetic models.

CONCLUSIONS

Data from the present study suggest that the IL-21 rs907715 polymorphism might be associated with multiple ADs susceptibility in Caucasians. Especially, the allele G of intronic rs907715 in IL-21 confers increased risk of ADs.

Autoimmune diseases association study with the KIAA1109-IL2-IL21 region in a Tunisian population

Autoimmune diseases (ADs) share several genetic factors resulting in similarity of disease mechanisms. For instance polymorphisms from the KIAA1109-interleukin 2 (IL2)-IL21 block in the 4q27 chromosome, has been associated with a number of autoimmune phenotypes. Here we performed a haplotype-based analysis of this AD related region in Tunisian patients. Ten single nucleotide polymorphisms (rs6534347, rs11575812, rs2069778, rs2069763, rs2069762, rs6852535, rs12642902, rs6822844, rs2221903, rs17005931) of the block were investigated in a cohort of 93 systemic lupus erythematosus (SLE), 68 ulcerative colitis (UC), 39 Crohn's disease (CD) patients and 162 healthy control subjects of Tunisian origin. In SLE population, haplotypes AGCAGGGTC, AGAAGAGTC, AGAAGGGTC and AGCCGAGTC provided significant evidence of association with SLE risk (p = 0.013, 0.028, 0.018 and 0.048, respectively). In the UC population, haplotype AGCCGGGTC provided a susceptibility effect for UC (p = 0.025). In the CD population, haplotype CAGGCC showed a protective effect against the development of CD (p = 0.038). Haplotype AAGGTT provided significant evidence to be associated with CD risk (p = 0.007). Our results support the existence of the associations found in the KIAA1109/IL2/IL21 gene region with ADs, thus confirms that the 4q27 locus may contribute to the genetic susceptibility of ADs in the Tunisian population.

Interleukin-21: a double-edged sword with therapeutic potential

Interleukin-21 is a cytokine with broad pleiotropic actions that affect the differentiation and function of lymphoid and myeloid cells. Since its discovery in 2000, a tremendous amount has been learned about its biological actions and the molecular mechanisms controlling IL-21-mediated cellular responses. IL-21 regulates both innate and adaptive immune responses, and it not only has key roles in antitumour and antiviral responses but also exerts major effects on inflammatory responses that promote the development of autoimmune diseases and inflammatory disorders. Numerous studies have shown that enhancing or inhibiting the action of IL-21 has therapeutic effects in animal models of a wide range of diseases, and various clinical trials are underway. The current challenge is to understand how to specifically modulate the actions of IL-21 in the context of each specific immune response or pathological situation. In this Review, we provide an overview of the basic biology of IL-21 and discuss how this information has been - and can be - exploited therapeutically.

Interleukin and interleukin receptor gene polymorphisms in inflammatory bowel diseases susceptibility

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), represents a group of chronic inflammatory disorders caused by dysregulated immune responses in genetically predisposed individuals. Genetic markers are associated with disease phenotype and long-term evolution, but their value in everyday clinical practice is limited at the moment. IBD has a clear immunological background and interleukins play key role in the process. Almost 130 original papers were revised including meta-analysis. It is clear these data are very important for understanding the base of the disease, especially in terms of clinical utility and validity, but text often do not available for the doctors use these in the clinical practice nowadays. We conducted a systematic review of the current literature on interleukin and interleukin receptor gene polymorphisms associated with IBD, performing an electronic search of PubMed Database from publications of the last 10 years, and used the following medical subject heading terms and/or text words: IBD, CD, UC, interleukins and polymorphisms.

Polymorphisms in the IL2RA and IL2RB genes in inflammatory bowel disease risk

Associations with different autoimmune diseases of polymorphisms in genes encoding the IL2RA and IL2RB subunits (located in 10p15 and 22q13, respectively), were identified through genome-wide studies. Polymorphisms in these two genes were studied in 107 inflammatory bowel disease (IBD) patients (39 Crohn's disease [CD] and 68 ulcerative colitis [UC]) and in 162 ethnically healthy controls from Tunisia (Sfax). Two of the 15 IL2RA single-nucleotide polymorphisms (SNPs) genotyped (rs4749924 and rs706778) were significantly associated with UC (pcorr=0.018 and 0.048, respectively), but no evidence of association with CD was observed. The IL2RA GTCT haplotype was also more frequent in UC patients compared to controls (2.6% vs. 0%; p=0.002). One of the 6 IL2RB SNPs genotyped (rs743776) was significantly associated with CD (pcorr= 0.039), but no evidence of association with UC was observed. No significant association between IL2RB haplotypes was observed among investigated groups. Our study identified markers in the IL2RA and IL2RB genes that are significantly associated with UC and CD, respectively. Our results supporting IL2RA and IL2RB as promising candidate genes for IBD and suggesting a potential role of IL2R in the pathogenesis of IBD, likely involves regulatory T cells.

Role of interleukin-21 isoform in dextran sulfate sodium (DSS)-induced colitis

Interleukin-21 (IL-21) is overproduced in human intestines affected by inflammatory bowel disease (IBD) and in the gut of mice with DSS-induced colitis. IL-21-deficient mice are largely protected against DSS-induced colitis, indicating that IL-21 plays a key role in the development of IBD. We previously identified a novel IL-21 isoform named IL-21iso. In this study, we found that in addition to the conventional IL-21, IL-21iso mRNA was also expressed in the colon with DSS-induced colitis. To investigate whether IL-21iso plays a role in DSS-induced colitis, we established transgenic mice (mIL-21iso-Tg mice) that expressed mouse IL-21iso under the control of the lck proximal promoter. Although mIL-21iso-Tg mice did not have any gross physical abnormalities, their peripheral lymphocytes counts were higher than those in wild-type littermates. Notably, their CD8(+) T cell and CD4(+) effector memory T-cell populations were elevated. DSS-induced colitis was far more severe in the mIL-21iso-Tg mice than in wild-type mice, and was accompanied by a marked loss of body weight and by colon inflammation with increased cellular infiltration. In DSS-treated mice, colon tissues from mIL-21iso-Tg mice had significantly higher gene activation levels for cytokines such as IL-17A, TNF-α, IL-6, IL-10, and IL-4, and for transcription factors such as T-bet, GATA-3, RORγt, and Foxp3, than were found in wild-type mice. These results indicate that besides IL-21, IL-21iso may be another regulator of gut inflammation.

In-vitro characterization of novel and functional regulatory SNPs in the promoter region of IL2 and IL2R alpha in a Gabonese population

Background

The selection pressure imposed by the parasite has a functional consequence on the immune genes, leading to altered immune function in which regulatory T cells (Tregs) induced by parasites during infectious challenges modulate or thwart T effector cell mechanism.

Methods

We identified and investigated regulatory polymorphisms in the immune gene IL2 and its receptor IL2R alpha (also known as CD25) in Gabonese individuals exposed to plentiful parasitic infections.

Results

We identified two reported variants each for IL2 and its receptor IL2R alpha gene loci. Also identified were two novel variants, -83 /-84 CT deletions (ss410961576) for IL2 and -409C/T (ss410961577) for IL2R alpha. We further validated all identified promoter variants for their allelic gene expression using transient transfection assays. Three promoter variants of the IL2 locus revealed no significant expression of the reporter gene. The identified novel variant (ss410961577C/T) of the IL2R alpha revealed a significant higher expression of the reporter gene in comparison to the major allele (P<0.05). In addition, the rs12722616C/T variant of the IL2R alpha locus altered the transcription factor binding site TBP (TATA box binding protein) and C/EBP beta (CCAAT/enhancer binding protein beta) that are believed to regulate the Treg function.

Conclusions

The identification and validation of such regulatory polymorphisms in the immune genes may provide a basis for future studies on parasite susceptibility in a population where T cell functions are compromised.

Implication of IL-2/IL-21 region in systemic sclerosis genetic susceptibility

OBJECTIVE

The interleukin 2 (IL-2) and interleukin 21 (IL-21) locus at chromosome 4q27 has been associated with several autoimmune diseases, and both genes are related to immune system functions. The aim of this study was to evaluate the role of the IL-2/IL-21 locus in systemic sclerosis (SSc).

PATIENTS AND METHODS

The case control study included 4493 SSc Caucasian patients and 5856 healthy controls from eight Caucasian populations (Spain, Germany, The Netherlands, USA, Italy, Sweden, UK and Norway). Four single nucleotide polymorphisms (rs2069762, rs6822844, rs6835457 and rs907715) were genotyped using TaqMan allelic discrimination assays.

RESULTS

We observed evidence of association of the rs6822844 and rs907715 variants with global SSc (pc=6.6E-4 and pc=7.2E-3, respectively). Similar statistically significant associations were observed for the limited cutaneous form of the disease. The conditional regression analysis suggested that the most likely genetic variation responsible for the association was the rs6822844 polymorphism. Consistently, the rs2069762A-rs6822844T-rs6835457G-rs907715T allelic combination showed evidence of association with SSc and limited cutaneous SSc subtype (pc=1.7E-03 and pc=8E-4, respectively).

CONCLUSIONS

These results suggested that the IL-2/IL-21 locus influences the genetic susceptibility to SSc. Moreover, this study provided further support for the IL-2/IL-21 locus as a common genetic factor in autoimmune diseases.

Generation and characterization of human anti-human IL-21 neutralizing monoclonal antibodies

Interleukin-21 (IL-21) is a type I four-helical bundle cytokine that exerts a variety of significant effects on many hematopoietic cells, including T and B lymphocytes and natural killer cells. IL-21 is produced predominantly by CD4+ T cells and natural killer T cells and, when aberrantly overexpressed, appears to play important roles in a wide variety of autoimmune disorders. To generate potential therapeutic reagents capable of inhibiting IL-21 for clinical use, we immunized human immunoglobulin transgenic mice with IL-21 and then identified and cloned a panel of human anti-human IL-21 binding monoclonal antibodies. IL-21 neutralizing and IL-21-binding, non-neutralizing antibodies were assigned to distinct epitope "bins" based on surface plasmon resonance competition studies. The most potent neutralizing antibodies had extremely high (sub pM) affinity for IL-21 and were able to block IL-21 activity in various biological assays using either an IL-21R-transfected pre-B-cell line or primary human B cells, and their neutralizing activity was, in some cases, superior to that of a soluble form of the high affinity heterodimeric IL-21 receptor. Characterization of this panel of IL-21 antibodies provided the basis for the selection of a therapeutic candidate antibody capable of inhibiting IL-21 activity for the treatment of autoimmune and inflammatory diseases.

Fine-mapping and transethnic genotyping establish IL2/IL21 genetic association with lupus and localize this genetic effect to IL21

OBJECTIVE

Genetic association of the IL2/IL21 region at chromosome 4q27 has previously been reported in lupus and a number of autoimmune and inflammatory diseases. This study was undertaken to determine whether this genetic effect could be localized, using a very large cohort of lupus patients and controls.

METHODS

We genotyped 45 tag single-nucleotide polymorphisms (SNPs) across the IL2/IL21 locus in 2 large independent lupus sample sets. We studied a set of subjects of European descent consisting of 4,248 lupus patients and 3,818 healthy controls, and an African American set of 1,569 patients and 1,893 healthy controls. Imputation in 3,004 additional controls from the Wellcome Trust Case Control Consortium was also performed. Genetic association between the genotyped markers was determined, and pairwise conditional analysis was performed to localize the independent genetic effect in the IL2/IL21 locus in lupus.

RESULTS

We established and confirmed the genetic association between IL2/IL21 and lupus. Using conditional analysis and transethnic mapping, we localized the genetic effect in this locus to 2 SNPs in high linkage disequilibrium: rs907715 located within IL21 (odds ratio 1.16 [95% confidence interval 1.10-1.22], P=2.17×10(-8)) and rs6835457 located in the 3'-untranslated flanking region of IL21 (odds ratio 1.11 [95% confidence interval 1.05-1.17], P=9.35×10(-5)).

CONCLUSION

Our findings establish the genetic association between lupus and IL2/IL21 with a genome-wide level of significance. Further, our findings indicate that this genetic association within the IL2/IL21 linkage disequilibrium block is localized to IL21. If other autoimmune IL2/IL21 genetic associations are similarly localized, then the IL21 risk alleles would be predicted to operate by a fundamental mechanism that influences the course of a number of autoimmune disease processes.

Genetics of rheumatoid arthritis: GWAS and beyond

The study of complex genetics in autoimmune diseases has progressed at a tremendous pace over the last 4 years, as a direct result of the enormous gains made by genome wide association studies (GWAS). Novel genetic findings are continuously being reported alongside the rapid development of genetic technologies, sophisticated statistical analysis, and larger sample collections. It is now becoming clear that multiple genes contribute to disease risk in many complex genetic disorders including rheumatoid arthritis (RA) and that there are common genetic risk factors that underlie a spectrum of autoimmune diseases. This review details the current genetic landscape of RA, and describes what GWAS has taught us in terms of missing heritability, subsets of disease, existence of genetic heterogeneity, and shared autoimmune risk loci. Finally, this review addresses the initial challenges faced in translating the wealth of genetic findings into determining the biological mechanisms that contribute to the relationship between genotype and phenotype. Unraveling the mechanism of how genes directly influence the cause of RA will lead to a better understanding of the disease and will ultimately have a direct clinical impact, informing the development of new therapies that can be utilized in the treatment of RA.

Role of the xenobiotic receptor in inflammatory bowel disease

BACKGROUND

Gene-environment interplay modulates inflammatory bowel diseases (IBD). Dioxin-like compounds can activate the aryl hydrocarbon receptor (AhR) and alter macrophage function as well as T-cell polarization. We hypothesized that attenuation of the AhR signaling pathway will ameliorate colitis in a murine model of IBD.

METHODS

Dextran sulfate sodium (DSS) colitis was induced in C57BL/6 AhR null mice (AhR(-/-) ), heterozygous mice (AhR(-/+) ), and their wildtype (WT) littermates. Clinical and morphopathological parameters were used to compare the groups.

PATIENTS

AhR pathway activation was analyzed in biopsy specimens from 25 IBD patients and 15 healthy controls.

RESULTS

AhR(-/-) mice died before the end of the treatment. However, AhR(-/+) mice exhibited decreased disease activity compared to WT mice. The AhR(-/+) mice expressed less proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α) (6.1- versus 15.7-fold increase) and IL17 (23.7- versus 67.9-fold increase) and increased antiinflammatory IL-10 (2.3-fold increase) compared with the AhR(+/+) mice in the colon. Colonic macrophage infiltration was attenuated in the AhR(-/+) group. AhR and its downstream targets were significantly upregulated in IBD patients versus control (CYP1A1 -19.9, and IL8- 10-fold increase).

CONCLUSIONS

Attenuation of the AhR receptor expression resulted in a protective effect during DSS-induced colitis, while the absence of AhR exacerbated the disease. Abnormal AhR pathway activation in the intestinal mucosa of IBD patients may promote chronic inflammation. Modulation of AhR signaling pathway via the diet, cessation of smoking, or administration of AhR antagonists could be viable strategies for the treatment of IBD.

Interleukin-21 triggers effector cell responses in the gut

In the gut of patients with Crohn's disease and patients with ulcerative colitis, the major forms of inflammatory bowel diseases (IBD) in humans, the tissue-damaging immune response is mediated by an active cross-talk between immune and non-immune cells. Accumulating evidence indicates also that cytokines produced by these cells play a major role in initiating and shaping this pathologic process. One such cytokine seems to be interleukin (IL)-21, a member of the common gamma-chain-receptor family. IL-21 is produced in excess in the inflamed intestine of patients with IBD mostly by activated CD4+ T helper cells co-expressing interferon-gamma and follicular T helper cells. Moreover, both in vitro and in vivo studies indicate that excessive IL-21 production leads to the activation of multiple signaling pathways that expand and sustain the ongoing mucosal inflammation. In this article, we review the available data supporting the pathogenic role of IL-21 in IBD.

Only one independent genetic association with rheumatoid arthritis within the KIAA1109-TENR-IL2-IL21 locus in Caucasian sample sets: confirmation of association of rs6822844 with rheumatoid arthritis at a genome-wide level of significance

INTRODUCTION

The single nucleotide polymorphism (SNP) rs6822844 within the KIAA1109-TENR-IL2-IL21 gene cluster has been associated with rheumatoid arthritis (RA). Other variants within this cluster, including rs17388568 that is not in linkage disequilibrium (LD) with rs6822844, and rs907715 that is in moderate LD with rs6822844 and rs17388568, have been associated with a number of autoimmune phenotypes, including type 1 diabetes (T1D). Here we aimed to: one, confirm at a genome-wide level of significance association of rs6822844 with RA and, two, evaluate whether or not there were effects independent of rs6822844 on RA at the KIAA1109-TENR-IL2-IL21 locus.

METHODS

A total of 842 Australasian RA patients and 1,115 controls of European Caucasian ancestry were genotyped for rs6822844, rs17388568 and rs907715. Meta-analysis of these data with published and publicly-available data was conducted using STATA.

RESULTS

No statistically significant evidence for association was observed in the Australasian sample set for rs6822844 (odds ratio (OR)=0.95 (0.80 to 1.12), P=0.54), or rs17388568 (OR=1.03 (0.90 to 1.19), P=0.65) or rs907715 (OR=0.98 (0.86 to 1.12), P=0.69). When combined in a meta-analysis using data from a total of 9,772 cases and 10,909 controls there was a genome-wide level of significance supporting association of rs6822844 with RA (OR=0.86 (0.82 to 0.91), P=8.8x10(-8), P=2.1x10(-8) including North American Rheumatoid Arthritis Consortium data). Meta-analysis of rs17388568, using a total of 6,585 cases and 7,528 controls, revealed no significant association with RA (OR=1.03, (0.98 to 1.09); P=0.22) and meta-analysis of rs907715 using a total of 2,689 cases and 4,045 controls revealed a trend towards association (OR=0.93 (0.87 to 1.00), P=0.07). However, this trend was not independent of the association at rs6822844.

CONCLUSIONS

The KIAA1109-TENR-IL2-IL21 gene cluster, that encodes an interleukin (IL-21) that plays an important role in Th17 cell biology, is the 20th locus for which there is a genome-wide (P Collapse

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MESH Headings

• Aged
• Aged, 80 and over
• Alleles
• Arthritis, Rheumatoid/ethnology
• Arthritis, Rheumatoid/genetics
• Australia
• Case-Control Studies
• Female
• GTPase-Activating Proteins/genetics
• Genetic Predisposition to Disease/genetics
• Genotype
• Humans
• Interleukin-2/genetics
• Interleukins/genetics
• Male
• Microtubule-Associated Proteins/genetics
• Middle Aged
• New Zealand
• Polymorphism, Single Nucleotide/genetics
• White People/ethnology
• White People/genetics

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Grants

• 076113 Wellcome Trust

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Affiliation(s)

Jade E Hollis-Moffatt Department of Biochemistry, 710 Cumberland Street, University of Otago, Dunedin 9054, New Zealand
Michael Chen-Xu Department of Biochemistry, 710 Cumberland Street, University of Otago, Dunedin 9054, New Zealand
Ruth Topless Department of Biochemistry, 710 Cumberland Street, University of Otago, Dunedin 9054, New Zealand
Nicola Dalbeth Department of Medicine, 85 Park Road, University of Auckland, Auckland 1142, New Zealand
Peter J Gow Department of Rheumatology, Middlemore Hospital, Hospital Road, Auckland 1640, New Zealand
Andrew A Harrison Department of Medicine, 23A Mein Street, University of Otago, Wellington 6242, New Zealand
John Highton Department of Medicine, Great King Street, University of Otago, Dunedin 9054, New Zealand
Peter BB Jones Department of Medicine, 85 Park Road, University of Auckland, Auckland 1142, New Zealand
Michael Nissen Department of Medicine, Daws Road, Flinders Medical Centre and Repatriation General Hospital, Adelaide 5041, Australia
Malcolm D Smith Department of Medicine, Daws Road, Flinders Medical Centre and Repatriation General Hospital, Adelaide 5041, Australia
Andre van Rij Department of Surgery, Great King Street, University of Otago, Dunedin 9054, New Zealand
Gregory T Jones Department of Surgery, Great King Street, University of Otago, Dunedin 9054, New Zealand
Lisa K Stamp Department of Medicine, Riccarton Avenue, University of Otago, Christchurch 8140, New Zealand
Tony R Merriman Department of Biochemistry, 710 Cumberland Street, University of Otago, Dunedin 9054, New Zealand

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Update on the genetic risk factors for rheumatoid arthritis

Rheumatoid arthritis (RA) is a complex disease, meaning that multiple genetic variants, environmental factors and random events interact to trigger pathological pathways. Although many of these etiological factors have not yet been identified, recent groundbreaking advances have expanded our knowledge about the genetic factors that contribute to RA. Here, we review the most recent findings on the genetic risk factors for RA. First, we give an overview of the genetics of RA and briefly describe the susceptibility loci discovered prior to the availability of genome-wide association studies (GWAS). Second, we focus on the newly discovered RA loci that have arisen from GWAS in populations of European ancestry. Through these studies, the number of established RA susceptibility loci has now grown to 13. Third, we discuss several important issues emerging from GWAS, such as ethnic heterogeneity and shared autoimmunity risk loci. Finally, we discuss what still needs to be accomplished before a more complete picture of the genetic risk to RA can be attained.

The 4q27 locus and prostate cancer risk

Background

Chronic inflammation is considered to be implicated in the development of prostate cancer. In this study we are the first to investigate a potential association between variants in an autoimmune related region on chromosome 4q27 and prostate cancer risk. This region harbors two cytokine genes IL-2 and the recently described IL-21.

Methods

We genotyped six variants previously associated with autoimmune disease (namely rs13151961, rs13119723, rs17388568, rs3136534, rs6822844 and rs6840978) and one functional IL-2 promoter variant (rs2069762) for possible association with prostate cancer risk using the Australian Risk Factors for Prostate Cancer case-control Study.

Results

Overall, our results do not support an association between the seven variants at position 4q27 and prostate cancer risk. Per allele odds ratios (ORs) were not significantly different from 1 (all P-values = 0.06). However, we found suggestive evidence for a significant association between the presence of the rs13119723 variant (located in a protein of unknown function) and men with a family history of prostate cancer in first-degree relatives (P-value for interaction 0.02). The per allele OR associated with this variant was significantly higher than 1 (2.37; 95% C.I. = 1.01-5.57).

Conclusions

We suggest that genetic variation within the chromosome 4q27 locus might be associated with prostate cancer susceptibility in men with a family history of the disease. Furthermore, our study alludes to a potential role of unknown protein KIAA1109 in conferring this risk.

Common and different genetic background for rheumatoid arthritis and coeliac disease

Recent genome-wide association studies (GWAS) have revealed genetic risk factors in autoimmune and inflammatory disorders. Several of the associated genes and underlying pathways are shared by various autoimmune diseases. Rheumatoid arthritis (RA) and coeliac disease (CD) are two autoimmune disorders which have commonalities in their pathogenesis. We aimed to replicate known RA loci in a Dutch RA population, and to investigate whether the effect of known RA and CD risk factors generalize across the two diseases. We selected all loci associated to either RA or CD in a GWAS and confirmed in an independent cohort, with a combined P-value cut-off P < 5 x 10(-6). We genotyped 11 RA and 11 CD loci in 1368 RA patients, 795 CD patients and 1683 Dutch controls. We combined our results in a meta-analysis with UK GWAS on RA (1860 cases; 2938 controls) and CD (767 cases; 1422 controls). In the Dutch RA cohort, the PTPN22 and IL2/IL21 variants showed convincing association (P = 3.4 x 10(-12) and P = 2.8 x 10(-4), respectively). Association of RA with the known CD risk variant in the SH2B3 was also observed, predominantly in the subgroup of rheumatoid factor-positive RA patients (P = 0.0055). In a meta-analysis of Dutch and UK data sets, shared association with six loci (TNFAIP3, IL2/IL21, SH2B3, LPP, MMEL1/TNFRSF14 and PFKFB3/PRKCQ) was observed in both RA and CD cohorts. We confirmed two known loci and identified four novel ones for shared CD-RA genetic risk. Most of the shared loci further emphasize a role for adaptive and innate immunity in these diseases.