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Journal of Immunology Research
Volume 2015, Article ID 279849, 5 pages
http://dx.doi.org/10.1155/2015/279849
Review Article

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

1Liyang People’s Hospital, Liyang 213300, China
2Translational Medicine Research Center of Jiangning Hospital and Liver Transplantation Center of First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China
3Department of Urology, Nanjing First Hospital, Nanjing Medical University, Nanjing 210029, China

Received 27 June 2014; Revised 5 January 2015; Accepted 12 January 2015

Academic Editor: Guixiu Shi

Copyright © 2015 Li Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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

1. Introduction

Crohn’s disease (CD) is a form of inflammatory bowel disease (IBD) that primarily affects the Caucasian population [1, 2]. It is a heritable disease which is influenced by many genetic risk factors [3]. Therefore, identification of gene risk factors of CD is beneficial for the clinical treatment of patients.

Interleukin 23 (IL-23) plays an important role in the inflammatory response against infection as a regulator of immune cells [4]. IL-23R which interacts with IL-23 is a protein consisting of an IL-12β1 and an IL-23R chain [5]. Recently, the mechanisms of IL-23R variants have been investigated in different autoimmune diseases [69]. Studies also have shown that rs7517847, the single nucleotide polymorphisms (SNPs) of the IL23R gene, are associated with CD occurring rate [10, 11]. However, the association between IL-23R polymorphisms and CD susceptibility are inconclusive and controversial due to small sample size in each of the published studies.

To better understand the association of IL-23R polymorphisms and CD susceptibility in Caucasians, we conducted a meta-analysis of all eligible studies and hope to yield more accurate and robust estimates.

2. Materials and Methods

2.1. Search Strategy

We searched for relevant studies in the following databases: EMBASE and PUBMED. Available studies for IL-23R polymorphism and CD were collected by different combinations of various key words: Interleukin-23 receptor, IL-23R; polymorphism, variant, or mutation; Crohn’s disease, CD. Languages restriction was not imposed in this research and only published studies with full text were included in this meta-analysis.

2.2. Inclusion and Exclusion Criteria of Trials

In the meta-analysis, the following inclusive selection criteria were set: (a) study design evaluating the association between IL-23R polymorphism and CD risk; (b) case control design; (c) Caucasians design. The following exclusive selection criteria were set: (a) no control cases; (b) duplication of the previous publication; (c) no available genotype frequency; for studies with overlapped or repeated data (d) no Caucasians.

2.3. Data Extraction

Eligible studies were extracted by 2 reviewers (Li Zhang and Yunjie Lu) independently according to the predesigned data collection form. The following information was extracted: first author’s name, publication year, country, ethnicity, immune suppressive protocol, number of cases and controls, and genotype distribution in both groups. Disagreement was resolved by discussion with a third reviewer (Guozhong Yao).

2.4. Statistical Analysis

For each trial, odds ratio (OR) with the 95% confidence interval (95% CI) of the survival rate was derived and calculated. Increased or decreased risk of CD was indicated by 95% CI without 1 for OR. The pooled ORs were estimated for allelic model (T allele versus G allele), homozygote comparison (TT versus GG) and heterozygote comparison (TG versus GG), dominant models (TT/TG versus GG), and recessive model (TT versus TG+GG). test was performed to assess the significance of the pooled OR. Between-study heterogeneity was assessed by the Cochran’s statistic and tests [12]. The random effects model was conducted if the test exhibited a or the test showed >50%. Otherwise, the fixed effects model would be conducted. For publication bias, the Begg’s funnel plot and Egger’s linear regression test were conducted, and was considered significant.

A fixed-effect model (based on Mantel-Haenszel method) was utilized to pool the data from different studies if the between-study heterogeneity was absent, or a random-effect model (based on DerSimonian and Laird method) was applied.

The statistical analysis was performed by STATA 10.0 (Stata Corp LP, College Station, TX, USA). All values are two-side.

3. Results

3.1. Selection of the Included Studies and Characteristics

The flow diagram of studies selection and exclusion reasons were represented in Figure 1. A total of 133 studies were identified by our first research; a number of 41 were preliminarily yielded out after excluding inappropriate studies and screening abstract-screening, full-text assessment. In these 41 studies, 30 were excluded, 11 articles containing rs7517847 in Caucasians were recruited for detailed analysis (Table 1), and these data built Table 1 [1323]. Each of them was independent. Thus, a total of 3279 CD cases and 4136 healthy controls were included in our meta-analysis. All of them were Caucasian and the diagnosis of CD was based on clinical manifestations and laboratory examinations and further biopsy.

Table 1: Characteristics of eligible studies included in the meta-analysis.
Figure 1: Flow diagram of the study selection process and specific reasons for exclusion.
3.2. Evaluation of the Association

The OR from all models indicated a significant association between rs7517847 and CD. After pooling all the eligible studies in Table 2, we found that the risk of CD was significantly associated with rs7517847 in dominant models (TT/TG versus GG: , 95% CI 1.277, 2.137), allelic model (T allele versus G allele: , 95% CI 1.198, 1.469), homozygote comparison (TT versus GG: , 95% CI 1.465, 2.437, Figure 2), heterozygote comparison (TG versus GG: , 95% CI 1.161, 1.960), and recessive model (TT versus TG/GG: , 95% CI 1.279, 1.552). These data demonstrate that rs7517847 increases the risk of CD among Caucasians with hospital-based studies.

Table 2: Stratified analysis of rs7517847 polymorphism and CD risk in eligible studies.
Figure 2: Forest plot for risk of CD associated with rs7517847 in Caucasian (TT versus GG. For each study, the estimate of OR and its 95% CI is plotted with a box and a horizontal line. Filled diamond pooled OR and its 95% CI).
3.3. Publication Bias

Begg’s funnel plot and Egger’s test were both performed to assess the publication bias of this meta-analysis. The shape of the funnel plots for homozygote comparison models seemed symmetrical (Figure 3). Then, the Egger’s test was used to provide statistical evidence of funnel plot symmetry. The results still did not suggest any evidence of publication bias. Thus, publication bias was not evident in present meta-analyses.

Figure 3: Begg’s funnel plot for publication bias test (TT versus GG for rs7517847).

4. Discussion

CD is associated with JAK2 signaling pathway which is activated by IL-23 and IL-23R receptor [24]. Previous studies suggested that the interruption of IL-23R SNPs might lead to the dysregulation of intestinal inflammation [25]. IL-23R gene variants also play an essential role in the development of many autoimmune diseases such as ankylosing spondylitis (AS), inflammatory bowel disease (IBD), and systemic lupus erythematosus (SLE) [7, 26, 27]. Therefore, researchers are focusing on observing the relationship between IL-23R gene polymorphisms and the risk of CD. However, the results are conflicting and controversial due to the different races and insufficient sample size. After pooling data for 11 studies in this meta-analysis, our results firstly demonstrate that T allele of rs7517847 was highly susceptible to CD in Caucasians.

One previous study showed that rs7517847 is a protective factor in rheumatoid arthritis (RA) in European population. Interestingly, RA is a systemic autoinflammatory disease which is associated with PTPN22/C1858T, while the organ-specific autoimmune disease CD is not [28, 29]. Thus, the mechanism of this genetic variant may not play a common role in different autoimmune diseases. More researches are required to observe the exact mechanisms of IL-23R gene polymorphism.

We should also mention the limitations of this meta-analysis. Primarily, all the studies were limited to the Caucasian. The allelic frequencies may be different in other ethnic groups. Secondly, publication bias might occur even if there is no significance in statistical test due to extracting published studies. Ultimately, owing to methodological limitations, this meta-analysis is retrospective. Two independent authors performed the process of study selection and data extraction and a third author resolved the discrepancy to minimize the bias.

In conclusion, our meta-analysis suggests that IL-23R rs7517847 confers susceptibility to CD in the Caucasians. Furthermore, more studies with larger scale are required to confirm these associations.

Conflict of Interests

All the authors declare that they do not have any commercial or associative interest that represents a conflict of interests in connection with the work submitted.

Authors’ Contribution

Li Zhang and Yunjie Lu contributed equally to this work and both are co-first authors.

Acknowledgment

This study was supported by the Medical Foundation of Liyang People Hospital.

References

  1. H. M. Malaty, J. K. Hou, and S. Thirumurthi, “Epidemiology of inflammatory bowel disease among an indigent multi-ethnic population in the United States,” Clinical and Experimental Gastroenterology, vol. 3, no. 1, pp. 165–170, 2010. View at Publisher · View at Google Scholar · View at Scopus
  2. E. V. Loftus Jr., “Clinical epidemiology of inflammatory bowel disease: incidence, prevalence, and environmental influences,” Gastroenterology, vol. 126, no. 6, pp. 1504–1517, 2004. View at Publisher · View at Google Scholar · View at Scopus
  3. J. van Limbergen, D. C. Wilson, and J. Satsangi, “The genetics of Crohn's disease,” Annual Review of Genomics and Human Genetics, vol. 10, pp. 89–116, 2009. View at Publisher · View at Google Scholar · View at Scopus
  4. C. Parham, M. Chirica, J. Timans et al., “A receptor for the heterodimeric cytokine IL-23 is composed of IL-12Rβ1 and a novel cytokine receptor subunit, IL-23R,” Journal of Immunology, vol. 168, no. 11, pp. 5699–5708, 2002. View at Publisher · View at Google Scholar · View at Scopus
  5. S. Aggarwal, N. Ghilardi, M.-H. Xie, F. J. De Sauvage, and A. L. Gurney, “Interleukin-23 promotes a distinct CD4 T cell activation state characterized by the production of interleukin-17,” The Journal of Biological Chemistry, vol. 278, no. 3, pp. 1910–1914, 2003. View at Publisher · View at Google Scholar · View at Scopus
  6. X. Wang, J. Huang, Z. Lin et al., “Single-nucleotide polymorphisms and expression of IL23R in Chinese ankylosing spondylitis patients,” Rheumatology International, vol. 30, no. 7, pp. 955–959, 2010. View at Publisher · View at Google Scholar · View at Scopus
  7. R. H. Duerr, K. D. Taylor, S. R. Brant et al., “A genome-wide association study identifies IL23R as an inflammatory bowel disease gene,” Science, vol. 314, no. 5804, pp. 1461–1463, 2006. View at Publisher · View at Google Scholar · View at Scopus
  8. B. Faragó, L. Magyari, E. Sáfrány et al., “Functional variants of interleukin-23 receptor gene confer risk for rheumatoid arthritis but not for systemic sclerosis,” Annals of the Rheumatic Diseases, vol. 67, no. 2, pp. 248–250, 2008. View at Publisher · View at Google Scholar · View at Scopus
  9. M. Cargill, S. J. Schrodi, M. Chang et al., “A large-scale genetic association study confirms IL12B and leads to the identification of IL23R as psoriasis-risk genes,” American Journal of Human Genetics, vol. 80, no. 2, pp. 273–290, 2007. View at Publisher · View at Google Scholar · View at Scopus
  10. H. Dong, Q. Li, Y. Zhang, W. Tan, and Z. Jiang, “IL23R gene confers susceptibility to ankylosing spondylitis concomitant with uveitis in a Han Chinese population,” PLoS ONE, vol. 8, no. 6, Article ID e67505, 2013. View at Publisher · View at Google Scholar · View at Scopus
  11. J. Wagner, W. H. Sim, J. A. Ellis et al., “Interaction of crohn's disease susceptibility genes in an australian paediatric cohort,” PLoS ONE, vol. 5, no. 11, Article ID e15376, 2010. View at Publisher · View at Google Scholar · View at Scopus
  12. E. Zintzaras and J. P. A. Ioannidis, “HEGESMA: genome search meta-analysis and heterogeneity testing,” Bioinformatics, vol. 21, no. 18, pp. 3672–3673, 2005. View at Publisher · View at Google Scholar · View at Scopus
  13. E. Safrany, M. Szabo, M. Szell et al., “Difference of interleukin-23 receptor gene haplotype variants in ulcerative colitis compared to Crohn's disease and psoriasis,” Inflammation Research, vol. 62, no. 2, pp. 195–200, 2013. View at Publisher · View at Google Scholar · View at Scopus
  14. M. Szabo, E. Safrany, B. Pazar et al., “Marked diversity of IL23R gene haplotype variants in rheumatoid arthritis comparing with Crohn's disease and ankylosing spondylitis,” Molecular Biology Reports, vol. 40, no. 1, pp. 359–363, 2013. View at Publisher · View at Google Scholar · View at Scopus
  15. L. R. Ferguson, D. Y. Han, A. G. Fraser, C. Huebner, W. J. Lam, and A. R. Morgan, “IL23R and IL12B SNPs and haplotypes strongly associate with Crohn's disease risk in a New Zealand population,” Gastroenterology Research and Practice, vol. 2010, Article ID 539461, 12 pages, 2010. View at Publisher · View at Google Scholar · View at Scopus
  16. M. Lauriola, G. Ugolini, S. Rivetti et al., “IL23R, NOD2/CARD15, ATG16L1 and PHOX2B polymorphisms in a group of patients with Crohn's disease and correlation with sub-phenotypes,” International Journal of Molecular Medicine, vol. 27, no. 3, pp. 469–477, 2011. View at Publisher · View at Google Scholar · View at Scopus
  17. M. Lacher, S. Schroepf, J. Helmbrecht et al., “Association of the interleukin-23 receptor gene variant rs11209026 with Crohn's disease in German children,” Acta Paediatrica, vol. 99, no. 5, pp. 727–733, 2010. View at Publisher · View at Google Scholar · View at Scopus
  18. A. Latiano, O. Palmieri, M. R. Valvano et al., “Replication of interleukin 23 receptor and autophagy-related 16-like 1 association in adult-and pediatric-onset inflammatory bowel disease in Italy,” World Journal of Gastroenterology, vol. 14, no. 29, pp. 4643–4651, 2008. View at Publisher · View at Google Scholar · View at Scopus
  19. A. Márquez, J. L. Mendoza, C. Taxonera et al., “IL23R and IL12B polymorphisms in Spanish IBD patients: no evidence of interaction,” Inflammatory Bowel Diseases, vol. 14, no. 9, pp. 1192–1196, 2008. View at Publisher · View at Google Scholar · View at Scopus
  20. M. L. Baptista, H. Amarante, G. Picheth et al., “CARD15 and IL23R influences Crohn's disease susceptibility but not disease phenotype in a Brazilian population,” Inflammatory Bowel Diseases, vol. 14, no. 5, pp. 674–679, 2008. View at Publisher · View at Google Scholar · View at Scopus
  21. W. G. Newman, Q. Zhang, X. Liu, C. I. Amos, and K. A. Siminovitch, “Genetic variants in IL-23R and ATG16L1 independently predispose to increased susceptibility to Crohn's disease in a Canadian population,” Journal of Clinical Gastroenterology, vol. 43, no. 5, pp. 444–447, 2009. View at Publisher · View at Google Scholar · View at Scopus
  22. T. Okazaki, M. H. Wang, P. Rawsthorne et al., “Contributions of IBD5, IL23R, ATG16L1, and NOD2 to Crohn's disease risk in a population-based case-control study: evidence of gene-gene interactions,” Inflammatory Bowel Diseases, vol. 14, no. 11, pp. 1528–1541, 2008. View at Publisher · View at Google Scholar
  23. J. Oliver, B. Rueda, M. A. López-Nevot, M. Gómez-García, and J. Martín, “Replication of an association between IL23R gene polymorphism with inflammatory bowel disease,” Clinical Gastroenterology and Hepatology, vol. 5, no. 8, pp. 977.e2–981.e2, 2007. View at Publisher · View at Google Scholar · View at Scopus
  24. C. A. Anderson, D. C. O. Massey, J. C. Barrett et al., “Investigation of Crohn's disease risk loci in ulcerative colitis further defines their molecular relationship,” Gastroenterology, vol. 136, no. 2, pp. 523.e3–529.e3, 2009. View at Publisher · View at Google Scholar · View at Scopus
  25. A. Zwiers, L. Kraal, T. C. T. M. van de Pouw Kraan, T. Wurdinger, G. Bouma, and G. Kraal, “Cutting edge: a variant of the IL-23R gene associated with inflammatory bowel disease induces loss of microRNA regulation and enhanced protein production,” Journal of Immunology, vol. 188, no. 4, pp. 1573–1577, 2012. View at Publisher · View at Google Scholar · View at Scopus
  26. N. Haroon, “Endoplasmic reticulum aminopeptidase 1 and interleukin-23 receptor in ankylosing spondylitis,” Current Rheumatology Reports, vol. 14, no. 5, pp. 383–389, 2012. View at Publisher · View at Google Scholar · View at Scopus
  27. E. Sánchez, B. Rueda, J. L. Callejas et al., “Analysis of interleukin-23 receptor (IL23R) gene polymorphisms in systemic lupus erythematosus,” Tissue Antigens, vol. 70, no. 3, pp. 233–237, 2007. View at Publisher · View at Google Scholar · View at Scopus
  28. Y. H. Lee, Y. H. Rho, S. J. Choi et al., “The PTPN22 C1858T functional polymorphism and autoimmune diseases—a meta-analysis,” Rheumatology, vol. 46, no. 1, pp. 49–56, 2007. View at Publisher · View at Google Scholar · View at Scopus
  29. N. J. Prescott, S. A. Fisher, C. Onnie et al., “A general autoimmunity gene (PTPN22) is not associated with inflammatory bowel disease in a British population,” Tissue Antigens, vol. 66, no. 4, pp. 318–320, 2005. View at Publisher · View at Google Scholar · View at Scopus