Influence of IL17A polymorphisms (rs2275913 and rs3748067) on the susceptibility to ulcerative colitis. Clin Exp Med. 2013;13:239-244. [PMID: 22955700 DOI: 10.1007/s10238-012-0206-5]

Recipient IL-17A polymorphism rs2275913 is associated with acute graft-versus-host disease after single-unit cord blood transplantation

BACKGROUND

Interleukin-17 (IL-17) is elevated in human inflammatory and autoimmune diseases. The polymorphism in the promoter region of the IL-17 A gene is associated with susceptibility to several inflammatory diseases, including acute graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation from adult donors. However, the impacts of IL-17 A polymorphism on cord blood transplantation (CBT) outcomes remain unclear.

OBJECTIVE

The objective of this study was to assess the impact of IL-17 A polymorphism rs2275913 on GVHD, survival, relapse, non-relapse mortality (NRM), and hematopoietic recovery after CBT.

STUDY DESIGN

We conducted a retrospective analysis of data from adult patients who underwent single-unit CBT at our institution from January 2005 to March 2023 for whose recipient or donor DNA samples were available. IL-17 A genotyping was performed using real-time polymerase chain reaction with the TaqMan® SNP genotyping assay for rs2275913.

RESULTS

A total of 158 recipients and 136 donors were evaluated in this study. Multivariate analysis showed that rs2275913 GA or AA recipients were associated with increased risk of grades II to IV acute GVHD compared to GG recipients (hazard ratio [HR], 1.46; 95% confidence interval [CI], 1.00-2.13; P = 0.047). Serum IL-17 A levels at eight weeks were significantly higher in rs2275913 GA or AA recipients compared to GG. The rs2275913 polymorphism did not affect survival, relapse, NRM, or hematopoietic recovery after single-unit CBT.

CONCLUSION

Our data showed recipient IL-17 A polymorphism rs2275913 was associated with the risk of grade II to IV acute GVHD in adults undergoing single-unit CBT. However, the rs2275913 polymorphism in recipients and donors did not affect survival or relapse. Thus, the polymorphism of IL-17 A rs2275913 in recipients might predict the risk of acute GVHD after single-unit CBT.

Secretion and surface display of binders of IL-23/IL-17 cytokines and their receptors in Lactococcus lactis as a therapeutic approach against inflammation

The cytokine IL-23 activates the IL-23 receptor (IL-23R) and stimulates the differentiation of naïve T helper (Th) cells into a Th17 cell population that secretes inflammatory cytokines and chemokines. This IL-23/Th17 proinflammatory axis drives inflammation in Crohn's disease and ulcerative colitis and represents a therapeutic target of monoclonal antibodies. Non-immunoglobulin binding proteins based on the Streptococcus albumin-binding domain (ABD) provide a small protein alternative to monoclonal antibodies. They can be readily expressed in bacteria. Lactococcus lactis is a safe lactic acid bacterium that has previously been engineered as a vector for the delivery of recombinant therapeutic proteins to mucosal surfaces. Here, L. lactis was engineered to display or secrete ABD-variants against the IL-17 receptor (IL-17R). Its expression and functionality were confirmed with flow cytometry using specific antibody and recombinant IL-17R, respectively. In addition, L. lactis were engineered into multifunctional bacteria that simultaneously express two binders from pNBBX plasmid. First, binders of IL-17R were combined with binder of IL-17. Second, binders of IL-23R were combined with binders of IL-23. The dual functionality of the bacteria was confirmed by flow cytometry using corresponding targets, namely the recombinant receptors IL-17R and IL-23R or the p19 subunit of IL-23. Binding of IL-17 was confirmed by ELISA. With the latter, 97% of IL-17 was removed from solution by 2 × 109 recombinant bacteria. Moreover, multifunctional bacteria targeting IL-17/IL-17R prevented IL-17A-mediated activation of downstream signaling pathways in HEK-Blue IL-17 cell model. Thus, we have developed several multifunctional L. lactis capable of targeting multiple factors of the IL-23/Th17 proinflammatory axis. This represents a novel therapeutic strategy with synergistic potential for the treatment of intestinal inflammations.

Molecular analyses of ADAMTS-1, -4, -5, and IL-17 a cytokine relationship in patients with ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that develops due to the impaired immune response in genetically susceptible individuals, and its etiopathogenesis is not fully elucidated. IL-17 A is a cytokine that is produced by a type of immune cell called Th17 cells and is involved in the immune response and inflammation. On the other hand, ADAMTS-1, -4, and - 5 are enzymes that are involved in the breakdown of extracellular matrix proteins, including proteoglycans, which are important components of the intestinal wall. This study aimed to evaluate the relationship between interleukin 17 (IL-17 A) cytokine, which plays a role in the pathogenesis of ulcerative colitis, and the inflammation-controlled a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-1, -4, and - 5 protein members.

METHODS

Bowel tissue samples and blood serum from 51 patients with UC and 51 healthy controls were included in this study. mRNA expression levels of the ADAMTS-1, -4, -5, and IL-17 A were analyzed by RT-qPCR, and immunohistochemical analyses were performed to evaluate ADAMTS-1, -4, -5, and IL-17 A proteins in tissue samples. In addition, ELISA analysis determined serum levels of the ADAMTS-1, -4, -5, and IL-17 A.

RESULTS

RT-qPCR results reveal that the expression of ADAMTS-1, -4, -5, and IL-17 A genes in the UC tissue samples were significantly high according to the control tissue samples. Also, ADAMTS-1, -4, -5, and IL-17 A proteins revealed enhanced expression pattern UC groups according to the control. Also, ADAMTS-1, -4, -5, and IL-17 A protein showed cytoplasmic localization patterns in both control and UC groups. The serum levels of ADAMTS-1,-5, and IL-17 A were significantly higher in UC samples than in the control group.

CONCLUSIONS

We observed a positive correlation between the ADAMTS-1, -5 and IL17A cytokine expression in UC samples. These results provide a new understanding of controlling crucial ADAMTS family protein members by IL-17 A cytokines with UC.

Association between IL-17A, IL-17F and IL-17RA gene polymorphisms and susceptibility to psoriasis and psoriatic arthritis: a meta-analysis

BACKGROUND

Psoriasis (Ps) is a chronic dermatosis characterized by erythematous-squamous plaques derived from an inflammatory response. The effect of polymorphisms in the genes that encode the members of the IL-17 family and their receptors has been studied to find an association with the susceptibility to Ps. However, the findings have not been conclusive.

OBJECTIVES

To describe the association between IL-17A, IL-17F and IL-17RA gene polymorphisms and susceptibility to Ps.

METHOD

A systematic review was conducted using the PubMed and Scopus databases to identify studies that evaluated the association between IL-17A, IL-17F, and IL-17RA gene polymorphisms and Ps susceptibility. This meta-analysis included reports published until June 2021. Heterogeneity was assessed using Cochran's Q-statistic test and I² statistics. The associations between polymorphisms and Ps susceptibility were determined by pooled OR with a 95% CI.

RESULTS

Fifteen studies were included. The frequency of the T allele of the IL-17F rs763780 polymorphism was significantly lower in patients with vulgar Ps (OR = 0.732, p = 0.026). The TT genotype of the IL-17F rs763780 polymorphism was significantly associated with a decreased frequency in individuals with Ps and psoriatic arthritis (PsA) (TT:TC + CC OR = 0.664, p = 0.046). Regarding IL-17RA polymorphisms, the AG genotype of the rs4819554 polymorphism showed a near-significant decrease in psoriasis risk compared to the GG genotype (AG:GG OR = 0.604, p = 0.050). Other polymorphisms in IL-17A, IL-17F and IL-17RA showed no association with Ps.

CONCLUSIONS

The T allele and TT genotype of the IL-17F rs763780 polymorphism may be associated with a decreased risk of psoriasis. Therefore, the implications of this variant on psoriasis pathogenesis and treatment require further investigation.

The IL23-IL17 Immune Axis in the Treatment of Ulcerative Colitis: Successes, Defeats, and Ongoing Challenges

Ulcerative colitis (UC) is a chronic relapsing disorder of the colonic tract, characterized by a dysregulated innate and adaptive immune response to gut microbiota that contributes to the perpetuation of intestinal inflammatory processes. The Interleukin (IL) 23/IL17 axis has been reported to play a key role in UC pathogenesis promoting Th17 cells and cytokines-related immune response. Recently, the blockade of IL23/IL17 pathways has been raised enormous interest in the treatment o several chronic inflammatory disorders. In this review, we summarize the emerging results from clinical trials that evoked both promise and discouragement in IL23/IL17 axis in the treatment of UC. Targeting IL23 p40 through Ustekinumab results safe and effective to induce and maintain clinical remission, low inflammatory indexes, mucosal healing, and a better quality of life. Studies targeting IL23 p19 through Mirikizumab, Risankizumab, Brazikumab and Guselkumab are still ongoing. To date, no clinical studies targeting IL17 pathway are ongoing in UC. IL-17 targeting is thought to have a context-dependent biological effect, based on whether cytokine is selectively targeted or if its function is dampened by the upstream block of IL23.

Genetic polymorphism in IL17RA induces susceptibility to Toxoplasma gondii infection in Brazilian pregnant women

Congenital toxoplasmosis is a parasitic disease caused by Toxoplasma gondii, an obligate intracellular parasite which can cause fetal death/abortion and can induce damage in the brain and eyes of the infected babies. The environmental and genetic factors associated with T. gondii and the maternal immune response, drive part of the pathogenesis of congenital toxoplasmosis. Thus, in this study, we aimed to investigate the allelic and genotypic frequencies of specific single nucleotide polymorphisms (SNPs) in the IL17A and IL17RA genes, as well as the production of IL-17A, IL-33, and CCL2 in pregnant women, from the State of Rio Grande do Norte, Brazil, further relating these along with the clinical parameters, to the toxoplasmosis infection. Through PCR-RFLP techniques, two SNPs implicated in Th17 immune response, IL17A rs2275913 (G> A) and IL17RA rs4819554 (A> G) modulation were evaluated in pregnant women, either infected or not infected by T. gondii. These women were also evaluated in terms of plasma release of CCL2, IL-33, and IL-17A which relate to hypertension, number of abortions, and ethnic pattern. The results showed that the G-allele of the SNP rs2275913 (IL17A) appeared to be protective in this population, while the rs4819554 (IL17RA) SNP G allele was associated with greater susceptibility to T. gondii infection [ρ value = 0.025; OR = 2.815 (1.118-7.089); CI = 95%]. None of the cytokines had any influence on the analyzed parameters (abortion and hypertension). In conclusion, our data suggest an immunogenic evidence of susceptibility to T. gondii infection driven by the rs4819554 (IL17RA) SNP G allele in Brazilian pregnant women. Further studies are needed to reinforce this trial marker in populations from distinct geographical areas as well as to confirm the protective pattern related to the G-allele of the SNP rs2275913 (IL17A) in pregnant women.

Association of Polymorphisms in Cytokine genes with susceptibility to Precancerous Lesions and Cervical Cancer: A systematic review with meta-analysis

Objectives: This study investigated the relationship between single-nucleotide polymorphisms (SNPs) in cytokine genes and the susceptibility to Squamous Intraepithelial Lesions (SIL), cervical cancer and HPV infection through a systematic review with meta-analysis. To verify the effect of SNPs, we also analyzed the transcription factor binding affinity using bioinformatics tools.Methods: Seven electronic databases (MEDLINE, Scielo, BIREME, PubMed, Scopus, Web of Science and Science Direct) were searched for case-control studies.Results: A total of 35 relevant case-control studies were meta-analyzed, including 7 cytokine genes and 15 SNPs. SNPs in IL-17A (rs2275913, rs3748067); IL-17 F (rs763780); IL-12A (rs568408); IL-12B (rs3212227); TNFA (rs1800629, rs361525); IL-1B (rs16944); IL-6 (rs1800795); IL-10 (rs1800896) genes were associated with increased risk for cervical cancer. No association was observed between meta-analyzed polymorphisms and SIL. Additional bioinformatics analysis suggested a possible transcriptional regulation pathway of the TNFA and IL-10 genes through the MZF1 (TNFA -308 G > A and IL-10 - 1082A>G) and ZNF263 (TNFA -238 G > A) transcription factors binding.Conclusion: Overall, 10 SNPs in cytokine genes were associated with increased risk for cervical cancer. Therefore, in our meta-analysis, these SNPs demonstrated to be potential biomarkers for predicting or identifying cases of high risk for SIL and cervical cancer.

IL12B and IL23R polymorphisms are associated with alopecia areata

Alopecia areata is an autoimmune disease in which activation of autoreactive T cells and inflammatory immune signals target the hair follicles autoantigens. Although cytokines are involved in regulating autoimmune inflammation, the specific involvement of these molecules in the pathogenesis of alopecia areata has been remained unsettled. Here, a possible influence of IL12B, IL17A, and IL23R variations on susceptibility to alopecia areata in Iranian patients was investigated. Genotyping of IL12B (rs3212227), IL17A (rs2275913), and IL23R (rs10889677) variants were performed by extracting genomic DNA from patients and controls. Gene expression was analyzed by real-time RT-PCR. The frequency of IL12B and IL23R gene polymorphisms is significantly higher in the patients than controls, while no significant difference was found for IL17A. Stratification of the patients with respect to age at disease onset indicated that CC genotype of IL12B (rs3212227) and AA genotype of IL23R (rs10889677) gene polymorphisms are significantly associated with late-onset alopecia areata disease. In contrast to IL17A and IL23R, IL12B gene expression levels elevated in patients to that of controls, but genotypes had no effect on levels of gene expression. Overall, our data confirmed that the IL12B and IL23R polymorphisms are associated with the risk to develop alopecia areata in our population.

Genetic polymorphisms of IL17A associated with Chagas disease: results from a meta-analysis in Latin American populations

Genetic factors and the immunologic response have been suggested to determine the susceptibility against the infection and the outcome of Chagas disease. In the present study, we analysed three IL17A genetic variants (rs4711998, rs8193036 and rs2275913) regarding the predisposition to Trypanosoma cruzi infection and the development of chronic Chagas cardiomyopathy (CCC) in different Latin American populations. A total of 2,967 individuals from Colombia, Argentina, Bolivia and Brazil, were included in this study. The individuals were classified as seronegative and seropositive for T. cruzi antigens, and this last group were divided into asymptomatic and CCC. For T. cruzi infection susceptibility, the IL17A rs2275913*A showed a significant association in a fixed-effect meta-analysis after a Bonferroni correction (P = 0.016, OR = 1.21, 95%CI = 1.06-1.41). No evidence of association was detected when comparing CCC vs. asymptomatic patients. However, when CCC were compared with seronegative individuals, it showed a nominal association in the meta-analysis (P = 0.040, OR = 1.20, 95%CI = 1.01-1.45). For the IL17A rs4711998 and rs8193036, no association was observed. In conclusion, our results suggest that IL17A rs2275913 plays an important role in the susceptibility to T. cruzi infection and could also be implicated in the development of chronic cardiomyopathy in the studied Latin American population.

IL-17A, MCP-1, CCR-2, and ABCA1 polymorphisms in children with non-alcoholic fatty liver disease

OBJECTIVE

The prevalence of non-alcoholic fatty liver disease in children has risen significantly, owing to the worldwide childhood obesity epidemic in the last two decades. Non-alcoholic fatty liver disease is closely linked to sedentary lifestyle, increased body mass index, and visceral adiposity. In addition, individual genetic variations also have a role in the development and progression of non-alcoholic fatty liver disease. The aim of this study was to investigate the gene polymorphisms of MCP-1 (-2518 A/G) (rs1024611), CCR-2 (190 G/A) (rs1799864), ABCA1 (883 G/A) (rs4149313), and IL-17A (-197 G/A) (rs2275913) in obese Turkish children with non-alcoholic fatty liver disease.

METHODS

The study recruited 186 obese children aged 10-17 years, including 101 children with non-alcoholic fatty liver disease and 85 children without non-alcoholic fatty liver disease. Anthropometric measurements, insulin resistance, a liver panel, a lipid profile, liver ultrasound examination, and genotyping of the four variants were performed.

RESULTS

No difference was found between the groups in respect to age and gender, body mass index, waist/hip ratio, or body fat ratio. In addition to the elevated ALT levels, AST and GGT levels were found significantly higher in the non-alcoholic fatty liver disease group compared to the non non-alcoholic fatty liver disease group (p<0.05). The A-allele of IL-17A (-197 G/A) (rs2275913) was associated with non-alcoholic fatty liver disease (odds ratio [OR] 2.05, 95% confidence interval: 1.12-3.77, p=0.02).

CONCLUSIONS

The findings of this study suggest that there may be an association between IL-17A (-197 G/A) (rs2275913) polymorphism and non-alcoholic fatty liver disease development in obese Turkish children.

Interleukin-17A and -17F single nucleotide polymorphisms associate with susceptibility of asthma in Chinese Han population

Interleukin 17 (IL-17) plays important roles in the progression of asthma. Genetic variants in the Il-17 may influence the immunopathogenesis of many diseases. Many studies have investigated the relevance of IL-17 polymorphism with cancers or immune diseases, including asthma. In this study, single nucleotide polymorphisms (SNPs) of IL-17 were explored by PCR-RFLP and verified by sequencing method. The frequencies of genotypes and alleles were analyzed. Haplotypes were analyzed with the SHEsis online program. The relationship between the genotypes of SNPs and IgE level was also investigated. The False Discovery Rate (FDR) correction was performed (P-adjusted < 0.05). The frequencies of A allele, GA and (GA + AA) genotype of rs3748067 were significantly higher in asthma patients. As for rs763780, the C allele in patients was more frequent than healthy controls. In addition, we found C carriers (CT + CC) were significantly higher in asthma patients. We further found that the haplotype CT for IL-17F (rs763780/rs2397084) was associated with an increased susceptibility of asthma, but this association did not survive after FDR correction. The level of serum total IgE in mutant group (GA + AA) of rs3748067 was significantly higher than the wild genotype (GG) group and control group. These results suggested that IL-17 SNPs, but not haplotypes may be associated with the susceptibility of asthma in Chinese Han population from central China.

Association between rs2275913 single-nucleotide polymorphism of the interleukin-17A gene and perioperative analgesic use in cosmetic orthognathic surgery

AIM

Interleukin-17A (IL-17A) plays an essential role in tissue inflammation by inducing proinflammatory cytokine and chemokine production and is related to innate immune reactions. IL-17A also contributes to neuroinflammation, neuropathic pain, and mechanical hypersensitivity after peripheral nerve injury in rodents. To clarify the contribution of IL-17A to pain-related phenotypes in humans, we investigated the association between pain-related phenotypes and the rs2275913 single-nucleotide polymorphism (SNP) of the IL-17A gene, which has been reported to be associated with rheumatoid arthritis, ulcerative colitis, and some cancers.

METHODS

The present study used a correlational design to examine the impact of the rs2275913 SNP on postoperative pain-related phenotypes in a group of patients who underwent cosmetic orthognathic surgery.

RESULTS

Carriers of the AA genotype had higher opioid requirements during and after surgery than carriers of the AG and GG genotypes (P = .009). Linear regression analysis indicated that opioid requirements linearly increased as the copy number of the A allele of the SNP increased (P = .008).

CONCLUSIONS

Opioid requirements during and after surgery are enhanced in carriers of the AA genotype of the rs2275913 SNP of the IL-17A gene, possibly through an enhancement of IL-17A function that induces inflammation that is related to the inflammatory pain stimulus.

Role of gene polymorphisms/haplotypes and serum levels of interleukin-17A in susceptibility to viral myocarditis

Interleukin-17A (IL-17A) has been implicated in the pathogenesis of viral myocarditis (VMC). However, the role of IL-17A polymorphisms in susceptibility to VMC has not been reported to date. The aim of this study was to explore the association between IL-17A variants as well as serum IL-17 levels with VMC. Three single-nucleotide polymorphisms (SNPs) (rs2275913, rs3819025, and rs3748067) were analyzed by the polymerase chain reaction-restriction fragment length polymorphism method in 236 VMC patients and 259 controls from China. Serum IL-17A levels were measured by enzyme-linked immunosorbent assay kits. Multivariable logistic regression analysis that the rs2275913 AA genotype and the haplotype -197A/+45G/+1249G (AGG) were associated with an increased risk of VMC (all P < 0.05). Consistent with these findings, the rs2275913 AA genotype was linked to higher serum IL-17A compared to GG/AG genotype (all P < 0.001). We observed no associations between the other two SNPs and risk of VMC. Serum IL-17A levels were significantly higher in the VMC group than controls (P < 0.001) and gradually increased with the increase of New York Heart Association grade in VMC patients (P < 0.05). Spearman correlation test revealed that the serum IL-17A level was correlated with the cardiac damage and left ventricular systolic functions among VMC patients (all P < 0.05). Our study reveals that IL-17A expression may contribute to the development and severity of VMC. The SNP rs2275913 in the IL-17A gene might exert influence on susceptibility to VMC via linking with the serum IL-17A level.

Association between SNPs at IL-17A and IL-17F and susceptibility to accelerated silicosis

The association between single nucleotide polymorphisms (SNPs) in the interleukin (IL)-17 gene and silicosis has been evaluated in different populations. The aim of the present study was to analyze the association between SNPs at IL-17A (−832A/G) and IL-17F (+7488A/G) and susceptibility to accelerated silicosis in the Iranian Kurdish population. We studied 48 patients with accelerated silicosis and 62 controls. Genomic DNA was isolated using the “salting out” method. PCR-RFLP was performed for all SNPs typing. The frequencies of A/A, A/G, and G/G genotypes at IL-17A (−832A/G) were 4 (8.33%), 23 (47.92%), and 21 (43.75%) in patients and 5 (8.06%), 35 (56.45%), and 22 (35.48%) in controls, respectively. The frequencies of A and G alleles at IL-17 (−832A/G) were 31 (32.29%) and 65 (67.71%) in patients, and 45 (36.29%) and 79 (63.71%) in the controls, respectively. The frequencies of A/A, A/G, and G/G genotypes at IL-17F (+7488A/G) were 1 (2.08%), 47 (97.92%), and 0 (0%) in patients, and 11 (17.74%), 51 (82.26%), and 0 (0%) in the controls, respectively. The frequencies of A and G alleles at IL-17F (+7488A/G) were 49 (51.04%) and 47 (48.96%) in patients, and 73 (58.87%) and 51 (41.13%) in the controls, respectively. IL-17F (+7488A/G) genotype was more frequent among the cases compared with controls (97.92% vs. 82.26%). The frequency of the IL-17F (+7488A/G) genotype was significantly greater in patients with accelerated silicosis (odds ratio = 10.13 95%; confidence interval = 1.2–81.5; p = 0.008). The IL-17F (+7488A/G) genotype revealed a significantly increased risk of accelerated silicosis ( p < 0.05). The IL-17F (+7488 G) allele was associated with an increased risk of accelerated silicosis, but in the case of the IL-17A (−832A/G) polymorphism, a significant association was not observed.

Polymorphisms in the IL-17 Gene (rs2275913 and rs763780) Are Associated with Hepatitis B Virus Infection in the Han Chinese Population

AIM

Interleukin-17 (IL-17) can accelerate the release of many pro-inflammatory cytokines. The purpose of our study was to investigate the potential association between polymorphisms in the IL-17 gene and susceptibility to hepatitis B virus (HBV) infection in the Han Chinese population.

METHODS

We recruited 596 HBV-infected patients and 612 ethnically matched controls, who were then genotyped for the IL-17A and IL-17F polymorphisms, rs2275913 and rs763780, respectively, by using TaqMan probe-based real-time polymerase chain reaction. The frequencies of the alleles and genotypes in patients and controls were compared by the χ² test.

RESULTS

Statistically significant differences in genotypic and allelic frequencies were revealed at both polymorphic sites between HBV-positive patients and controls (rs2275913: genotype χ² = 37.74, p < 0.001 and allele χ² = 22.17, p < 0.001, odds ratio [OR] = 0.654, 95% confidence interval [CI] = 0.548-0.781. rs763780: genotype χ² = 19.80, p < 0.001 and allele χ² = 18.78, p < 0.001, OR = 0.507, 95% CI = 0.371-0.692).

CONCLUSIONS

These results indicate that the IL-17A rs2275913 and IL-17F rs763780 polymorphisms are associated with HBV infection in the Han Chinese population. We conclude that possession of the GG genotype and the G allele at rs2275913, and the TT genotype and the T allele at rs763780 might increase the risk of HBV infection. Larger-scale, multiracial studies are necessary to evaluate the role of IL-17 polymorphisms in relation to an enhanced risk of HBV infection.

Meta-Analysis of Risk Association Between Interleukin-17A and F Gene Polymorphisms and Inflammatory Diseases

This meta-analysis examined the relationship between IL-17A (rs2275913) and IL17F (rs763780 T/C) gene polymorphisms and the risk of inflammatory diseases, including periodontitis, rheumatoid arthritis (RA), and inflammatory bowel disease. PubMed, MEDLINE, EMBASE, Web of Science, and Elsevier Science Direct were searched, and odds ratios (ORs) with 95% confidence interval (CI) were calculated to estimate the strength of the association. A total of 25 studies comprising 7,474 cases and 10,628 controls were included. Significant associations were found between inflammatory diseases and IL-17A rs2275913 A versus G allele (OR = 1.197, P = 0.033) and the GA versus GG genotype in the codominant model (OR = 1.406, P = 0.036). Our findings suggested that individuals who carry the rs2275913 A allele or GA genotype have a 20% or 41%-increased risk of inflammatory diseases compared with subjects with the G allele or GG genotype, respectively. With respect to IL-17F rs763780, the C versus T allele (OR = 1.94; P = 0.040), the TC versus TT (OR = 1.39; P = 0.041), the CC versus TT (OR = 2.71; P = 0.003), as well as the TC + CC versus TT genotype (OR = 1.83; P = 0.032) were risk factors for RA. In summary, our pooled analysis indicated that the IL-17A (rs2275913) and IL17F (rs763780 T/C) increased the RA risk.

The IL-17A rs2275913 single nucleotide polymorphism is associated with protection to tuberculosis but related to higher disease severity in Argentina

Mycobacterium tuberculosis (Mtb) causes nearly 10 millions of new tuberculosis disease cases annually. However, most individuals exposed to Mtb do not develop tuberculosis, suggesting the influence of a human genetic component. Here, we investigated the association of the rs2275913 SNP (G → A) from IL-17A and tuberculosis in Argentina by a case-control study. Furthermore, we evaluated in vitro the functional relevance of this SNP during the immune response of the host against Mtb and analyzed its impact on clinical parameters of the disease. We found an association between the AA genotype and tuberculosis resistance. Additionally, within the healthy donors population, AA cells stimulated with a Mtb lysate (Mtb-Ag) produced the highest amounts of IL-17A and IFN-γ, which further support the genetic evidence found. In contrast, within the tuberculosis patients population, AA Mtb-Ag stimulated cells showed the lowest immunological parameters and we evidenced an association between the AA genotype and clinical parameters of disease severity, such as severe radiological lesions and higher bacilli burden in sputum. Overall, our findings demonstrated that the AA genotype from the IL-17A rs2275913 SNP is positively associated with protection to active tuberculosis but related to higher disease severity in the Argentinean population.

Common variants in IL-17A/IL-17RA axis contribute to predisposition to and progression of congestive heart failure

Heart failure is characterized by immune activation leading to production and release of proinflammatory cytokines. Interleukin 17A (IL-17A) is a proinflammatory cytokine and multiple lines of evidence from animal and human studies suggest crucial roles of IL-17A in heart failure. Therefore, we investigated whether common polymorphisms of genes IL17A and IL17RA (coding interleukin 17 receptor A) contribute to genetic predisposition to heart failure and adverse clinical outcomes associated with it.A total of 1713 adult patients with congestive heart failure and 1713 age- and sex-matched controls were genotyped for promoter single nucleotide polymorphisms (SNPs), rs2275913 and rs8193037 in IL17A and rs4819554 in IL17RA, to assess the relationship between individual SNPs and the risk of congestive heart failure. Results showed that rs8193037 in IL17A was associated with the risk of congestive heart failure (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63-0.90, adjusted P = 0.002) after adjustment for multiple cardiovascular risk factors including age, sex, smoking status, diabetes, hypertension, and dyslipidemia. This association was evident in both ischemic and nonischemic heart failure (P = 0.005 and P = 0.05, respectively). Furthermore, prospective follow-up of 12.7 months for the occurrence of adverse clinical outcomes showed that rs4819554 in IL17RA was significantly associated with cardiovascular mortality (hazard ratio [HR] = 1.28; 95% CI = 1.02-1.59, adjusted P = 0.03) after adjustments for multiple cardiovascular risk factors and New York Heart Association functional class.This study demonstrated associations of rs8193037 in the promoter of IL17A with the risk of congestive heart failure, and of rs4819554 in the promoter of IL17RA with the risk of cardiovascular mortality in patients with congestive heart failure. These data lend further support to the notion that immune activation and genetic polymorphisms contribute to heart failure pathogenesis and progression.

Genetic Analysis of IL-17 Gene Polymorphisms in Gout in a Male Chinese Han Population

Interleukin (IL)-17 is a proinflammatory cytokine mainly secreted by activated T helper 17 cells and involved in inflammatory immune responses. This study aimed to investigate the association between IL-17 variants as well as serum IL-17 levels with gout in male Chinese Han individuals. A total of 1,101 male gout patients and 1,239 ethic-matched controls were enrolled. Genetic distributions of three variants (rs2275913 in IL-17A, rs763780 in IL-17F, and rs4819554 in IL-17RA) were detected by real-time polymerase chain reaction using the Taqman probe method. The plasma concentrations of IL-17A and IL-17F were measured in 228 gout patients and 198 controls that came from above samples by an enzyme-linked immunosorbent assay. No significant differences were observed in the genetic distribution of these polymorphisms between cases and controls (rs2275913: χ² = 0.15, p = 0.928 by genotype, χ² = 0.14, p = 0.711 by allele; rs763780: χ² = 2.24, p = 0.326 by genotype, χ² = 0.26, p = 0.609 by allele; rs4819554: χ² = 1.79, p = 0.409 by genotype, χ² = 1.46, p = 0.227 by allele). Levels of serum IL-17A and IL-17F were significantly decreased in gout patients (both p<0.001). However, no difference was observed in acute gout patients between different genotypic carriers of rs2275913 and rs763780 regarding serum IL-17A and IL-17F levels (p>0.05). Although the genetic variants in IL-17 we studied in this research do not appear to be involved in the development of gout in male Chinese Han individuals, the IL-17 cytokine family may participate in gouty inflammation in an undefined way, which requires further validation.

Genetic association between Interleukin-17A gene polymorphisms and the pathogenesis of Graves' disease in the Han Chinese population

OBJECTIVE

Graves' disease, one of the commonest autoimmune disorders, has a complex genetic basis. Interleukin-17A (IL-17A) is an important cytokine involved in innate and adaptive immune responses. This case-control study sought to investigate genetic association between the IL-17A gene and the process of Graves' disease (GD).

DESIGN AND METHODS

Our pilot study was performed on a cohort from Shanghai, which included 713 patients with GD and 756 healthy controls. A replicate cohort was from Xiamen, recruiting 444 patients with GD and 427 healthy subjects. Six single nucleotide polymorphisms (SNPs) (rs4711998, rs3819024, rs2275913, rs8193037, rs3819025 and rs3748067) within the IL-17A gene were genotyped by the SNPstream Genotyping Systems and Taqman PCR method.

RESULTS

In Shanghai cohorts, the frequencies of rs8193037 alleles were strongly different between patients with Graves' disease (G, 87·6% and A, 12·4%) and healthy controls (G, 91·4% and A, 8·6%) (P = 0·00067). The A carriers were associated with increased Graves' disease risks when compared with the G carriers (OR = 1·51, 95%CI = 1·19-1·92). In replicate cohorts, the proportion of individuals carrying the A allele of rs8193037 was significantly higher in patients with Graves' disease than in controls [Graves' disease vs control, 14·3% vs 9·1%, OR = 1·66 (95% CI: 1·23-2·24), P_allele  = 0·0082]. In addition, rs8193037 and rs3748067 were found to be different in both genotype and allele distributions in Graves' disease-associated ophthalmopathy patients and controls in Shanghai cohorts. Haplotype association analysis also identified five main haplotypes of those six SNPs.

CONCLUSION

These results suggested that the polymorphism of IL-17A rs8193037 was strongly associated with Graves' disease susceptibility in the Chinese Han population.z.

Association of inflammatory cytokine gene polymorphisms with inflammatory bowel disease in a Moroccan cohort

The purpose of this study was to investigate whether common variants in inflammatory and immune response genes influence inflammatory bowel disease (IBD) risk among Moroccan patients. Using a candidate gene approach, 10 single-nucleotide polymorphisms mapping on six genes (MIF_rs755622, TNFA_rs1800629, IL6_rs2069840, IL6R_rs2228145, IL6ST_rs2228044, IL17A (rs2275913, rs4711998, rs7747909, rs8193036, rs3819024)) were assessed in 510 subjects grouped in 199 IBD and 311 healthy controls. Genotyping was performed with the TaqMan allelic discrimination technology. The results were analyzed using PLINK software. The frequency of allele A for TNFA rs1800629 was significantly higher in ulcerative colitis (UC) patients compared with controls (30.16 vs 16.72%; P=0.0005; odds ratio (OR)=2.15; 95% confidence interval (CI)=1.39-3.32). Statistically significant association to UC was also found under dominant AA+AG vs GG (OR=1.85, 95% CI=1.07-3.21; P=0.02) and recessive models (OR=8.38; 95% CI=2.86-24.53; P=0.0001). In the same way, an association of TNFA rs1800629 variant was observed with IBD under recessive model AA vs AG+GG (OR=4.10; 95% CI=1.56-10.76; P=0.004). No evidence of significant associations was found for the remaining investigated polymorphisms. Our data suggest that TNFA gene promoter polymorphism participates in determining IBD susceptibility in Moroccan patients.

Genetic variants of interleukin 17A are functionally associated with increased risk of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in elderly populations worldwide. Inflammation, among many factors, has been suggested to play an important role in AMD pathogenesis. Interleukin 17 (IL-17) is a proinflammatory cytokine that has been implicated in the pathogenesis of various autoimmune diseases. In the current study, we examined two single nucleotide polymorphisms (SNPs), rs2275913G/A and rs3748067C/T, in the IL-17A gene between AMD patients and healthy controls. Results showed that rs2275913AA genotype and rs3748067TT genotype were associated with increased susceptibility to AMD (hazard ratio [HR], 1.75; 95 % confidence interval [CI], 1.07 to 3.02; P=0.023, and HR, 2.12; 95 % CI, 1.26 to 4.01; P=0.004; data were adjusted for age and sex). Next, we investigated the functional relevance of the two SNPs. In vitro stimulated peripheral blood mononuclear cells (PBMCs) from subjects possessing the rs2275913AA genotype produced significantly more IL-17 than those with the GG genotype. However, PBMCs with rs3748067TT genotype revealed significantly higher IL-17 production than those with rs3748067CC genotype only in AMD patients but not in controls. These data indicate IL-17A polymorphisms are associated with increased risk of AMD probably by affecting gene expression.

Role of IL-17 Variants in Preeclampsia in Chinese Han Women

Previous studies have suggested an important role for IL-17, mainly secreted by Th17 cells, in the development of systemic inflammation in preeclampsia (PE). This study therefore investigated the association between genetic variants in IL-17A, IL-17F, and IL-17RA and susceptibility to PE in Chinese Han women. We recruited 1,031 PE patients and 1,298 controls of later pregnant women, and used TaqMan allelic discrimination real-time PCR to genotype the polymorphisms of IL17A rs2275913, IL-17F rs763780, and IL-17RA rs4819554. No significant differences in genotypic or allelic frequencies were found at all three polymorphic sites between PE patients and controls (rs2275913: genotype χ2 = 0.218, p = 0.897 and allele χ2 = 0.157, p = 0.692, OR = 1.024, 95%CI 0.911-1.152; rs763780: genotype χ2 = 1.948, p = 0.377 and allele χ2 = 1.242, p = 0.265, OR = 0.897, 95%CI 0.741-1.086; rs4819554: genotype χ2 = 0.633, p = 0.729 and allele χ2 = 0.115, p = 0.735, OR = 1.020, 95%CI 0.908-1.146). There were also no significant differences in genetic distributions between mild/severe PE or early/late-onset PE and control subgroups. Our data indicate that the genetic variants of rs2275913 in IL-17A, rs763780 in IL-17F, and rs4819554 in IL-17RA may not play a role in the pathogenesis of PE in Chinese Han women. However, these findings should be confirmed in other ethnic populations.

The polymorphism rs763780 in the IL-17F gene is associated with response to biological drugs in patients with psoriasis

Psoriasis improves when IL-17 is blocked. Anti-TNF drugs reduce the IL-17 signaling pathway, and anti-IL-17 drugs are being developed to treat moderate-to-severe psoriasis. We analyzed three SNPs in IL-17A (rs2275913 and rs10484879) and IL-17F (rs763780) to look for an association with psoriasis and/or with response to anti-TNF drugs or ustekinumab. We included 197 healthy controls and 194 patients with moderate-to-severe psoriasis. The results of the univariate analysis showed an association between rs10484879 and psoriasis, although this relationship disappeared after adjustment for HLA-C (rs12191877). We also found an association between rs763780 (IL-17F) and response to ustekinumab (n = 70) and infliximab (n = 37) at 3 and 6 months and an association between rs763780 and the response to adalimumab at 6 months (n = 67).

Association study between IL-17A and IL-17F gene polymorphism and myasthenia gravis in Chinese patients

Alleles of IL-17A and IL-17F genes were reported to be associated with many inflammatory and autoimmune disorders in Asian patients. Serum level and mRNA of IL-17A in peripheral blood mononuclear cells were reported to be significantly higher in MG patients than in healthy controls. In experimental autoimmune myasthenia gravis (EAMG) animals, IL-17 may have effects on the severity of MG. This study investigated the association between four SNPs of IL-17A and IL-17F gene (rs8193036, rs2275913 and rs3748067 in IL-17A; rs763780 in IL-17F) and MG in Chinese patients. The allele frequencies were compared between 480 MG patients and 487 healthy controls, between each MG subgroup and the control group, and between each pairs of MG subgroups. Subgroups were specified by clinical features (onset age, gender, thymoma, AChRAb and muscle involvement at onset) and maximal severity during the follow-up. No associations were found between the four SNPs of IL-17A and IL-17F gene and MG in Chinese patients.

The Influence of Interleukin 17A and IL17F Polymorphisms on Chronic Periodontitis Disease in Brazilian Patients

A case-control study was conducted on patients with chronic periodontitis (CP) and healthy controls with the aim of evaluating possible association between interleukin 17A (IL17A) G197A (rs2275913) and IL17F T7488C (rs763780) polymorphisms and periodontitis. Genotypes were determined by PCR-RFLP method. Statistical analyses were conducted using the OpenEpi and SNPStas software to calculate Chi-square with Yates correction or Fisher's exact tests, odds ratios (OR), and 95% confidence intervals (CIs). SNPStas software was used to calculate Hardy-Weinberg equilibrium. IL17A AA genotype was more frequent in patients with chronic periodontitis (CP) in the codominant and recessive models (P = 0.09; OR = 2.53 and P = 0.03; OR = 2.46, resp.), the females with CP (P = 0.01, OR = 4.34), Caucasoid patients with CP (P = 0.01, OR = 3.45), and nonsmoking Caucasian patients with CP (P = 0.04, OR = 3.51). The IL17A A allele was also more frequent in Caucasians with CP (P = 0.04, OR = 1.59). IL17F T7488C polymorphism was not associated with chronic periodontitis. In these patients from Southern Brazil, the IL17A rs2275913 polymorphisms, IL17A AA genotype, and the A allele were associated with a susceptibility to chronic periodontitis.

Fusobacterium detected in colonic biopsy and clinicopathological features of ulcerative colitis in Japan

BACKGROUND AND AIMS

Fusobacterium species are part of the gut microbiome in humans, but some species have been recognized as opportunistic pathogens implicated in inflammatory diseases including inflammatory bowel diseases. Here, we performed prevalence screening of Fusobacterium in ulcerative colitis (UC) in Japanese patients.

METHODS

We examined Fusobacterium nucleatum (F. nucleatum) and whole Fusobacterium species (Pan-fusobacterium) by quantitative real-time PCR in 163 inflamed mucosae from 152 UC patients. Data were correlated with clinical subtypes of UC.

RESULTS

In an initial prevalence screen, F. nucleatum and Pan-fusobacterium were detected in 6.3 % (4/64) and 53.1 % (34/64). For all 163 mucosae, the prevalence of Pan-fusobacterium was 54.6 % (89/163). Pan-fusobacterium status was concordant in inflamed and normal adjacent samples, and the matched cases during 1-year follow-up colonoscopy. The higher amount of Pan-fusobacterium was observed in chronic continuous type compared to one attack and relapse/remitting type (p = 0.039). The higher amount of Pan-fusobacterium was also associated with rather mild clinical course of disease, such as non-steroid dependency (p = 0.015), non-refractory phenotype (p = 0.013), and non-severe phenotype (p = 0.04). Based on the distribution of Pan-fusobacterium measurable cases, we identified 10 cases as having a high amount of Pan-fusobacterium (FB-high). The clinicopathological features of FB-high UC cases were also highlighted by chronic continuous type and mild phenotypes of disease.

CONCLUSION

Whole Fusobacterium species, but not F. nucleatum, are common in UC patients and have a role in persistence of colonic inflammation in UC. However, Fusobacterium infection is associated with rather mild clinical phenotypes of UC.

Interleukin-17 SNPs and serum levels increase ulcerative colitis risk: A meta-analysis

AIM: To investigate the associations of interleukin-17 (IL-17) genetic polymorphisms and serum levels with ulcerative colitis (UC) risk.

METHODS: Relevant articles were identified through a search of the following electronic databases, excluding language restriction: (1) the Cochrane Library Database (Issue 12, 2013); (2) Web of Science (1945-2013); (3) PubMed (1966-2013); (4) CINAHL (1982-2013); (5) EMBASE (1980-2013); and (6) the Chinese Biomedical Database (1982-2013). Meta-analysis was conducted using STATA 12.0 software. Crude odds ratios and standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs) were calculated. All of the included studies met all of the following five criteria: (1) the study design must be a clinical cohort or a case-control study; (2) the study must relate to the relationship between IL-17A/F genetic polymorphisms or serum IL-17 levels and the risk of UC; (3) all patients must meet the diagnostic criteria for UC; (4) the study must provide sufficient information about single nucleotide polymorphism frequencies or serum IL-17 levels; and (5) the genotype distribution of healthy controls must conform to the Hardy-Weinberg equilibrium (HWE). The Newcastle-Ottawa Scale (NOS) criteria were used to assess the methodological quality of the studies. The NOS criteria included three aspects: (1) subject selection: 0-4; (2) comparability of subjects: 0-2; and (3) clinical outcome: 0-3. NOS scores ranged from 0 to 9, with a score ≥ 7 indicating good quality.

RESULTS: Of the initial 177 articles, only 16 case-control studies met all of the inclusion criteria. A total of 1614 UC patients and 2863 healthy controls were included in this study. Fourteen studies were performed on Asian populations, and two studies on Caucasian populations. Results of the meta-analysis revealed that IL-17A and IL-17F genetic polymorphisms potentially increased UC risk under both allele and dominant models (P < 0.001 for all). The results also showed that UC patients had higher serum IL-17 levels than healthy controls (SMD = 5.95, 95%CI: 4.25-7.65, P < 0.001). Furthermore, serum IL-17 levels significantly correlated with the severity of UC (moderate vs mild: SMD = 2.59, 95%CI: 0.03-5.16, P < 0.05; severe vs mild: SMD = 7.09, 95%CI: 3.96-10.23, P < 0.001; severe vs moderate: SMD = 5.84, 95%CI: 5.09-6.59, P < 0.001). The NOS score was ≥ 5 for all of the included studies. Based on the sensitivity analysis, no single study influenced the overall pooled estimates. Neither the Begger’s funnel plots nor Egger’s test displayed strong statistical evidence for publication bias (IL-17A/F genetic polymorphisms: t = -2.60, P = 0.019; serum IL-17 levels: t = -1.54, P = 0.141).

CONCLUSION: The findings strongly suggest that IL-17A/F genetic polymorphisms and serum IL-17 levels contribute to the development and progression of UC.

IL-17A, IL-17F and IL-23R Gene Polymorphisms in Polish Patients with Rheumatoid Arthritis

Among the complex network of inflammatory cells involved in the pathogenesis of rheumatoid arthritis (RA), Th17 cells have recently been identified as key cells in the promotion of autoimmune processes, and joint destruction. The IL-23/Th17 signalling pathway, consisting of IL-23/IL-23R, IL-17A and IL-17F encoding genes, represents a candidate way for RA development with possible involvement in disease susceptibility and effect on disease progression. The present study aimed to determine the association between the polymorphic variants of the IL-17A (rs2275913), IL-17F (rs763780) and IL-23R (rs11209026) genes and RA susceptibility, progression and response to therapy with TNF-α inhibitors. Eighty-nine patients and 125 healthy individuals were investigated. The IL-17A polymorphism was found to affect RA progression and response to anti-TNF treatment. Female patients carrying the IL-17A wild-type genotype more frequently presented with stage 4 (8/24 vs. 6/47; p = 0.058) and were characterized by more active disease (the highest DAS28 score >5.1) after 3 months of therapy with the TNF inhibitors (12/23 vs. 15/45; p = 0.040). The IL-17F polymorphism appeared to be associated with susceptibility to the disease. The presence of the IL-17F minor variant (OR 3.97; p < 0.001) and its homozygosity (OR 29.62; p < 0.001) was more frequent among patients than healthy individuals. These results suggest that the polymorphisms within the IL-17A and IL-17F genes play a significant role in RA.

Characteristics of Japanese inflammatory bowel disease susceptibility loci

BACKGROUND

There are substantial differences in inflammatory bowel disease (IBD) genetics depending on the populations examined. We aimed to identify Japanese population-specific or true culprit susceptibility genes through a meta-analysis of past genetic studies of Japanese IBD.

METHODS

For this study, we reviewed 2,703 articles. The review process consisted of three screening stages: we initially searched for relevant studies and then relevant single nucleotide polymorphisms (SNPs). Finally, we adjusted them for the meta-analysis. To maximize our chances of analysis, we introduced proxy SNPs during the first stage. To minimize publication bias, no significant SNPs and solitary SNPs without pairs were combined to be reconsidered during the third stage. Additionally, two SNPs were newly genotyped. Finally, we conducted a meta-analysis of 37 published studies in 50 SNPs located at 22 loci corresponding to the total number of 4,853 Crohn's disease (CD), 5,612 ulcerative colitis (UC) patients, and 14,239 healthy controls.

RESULTS

We confirmed that the NKX2-3 polymorphism is associated with common susceptibility to IBD and that HLA-DRB1*0450 alleles increase susceptibility to CD but reduce risk for UC while HLA-DRB1*1502 alleles increase susceptibility to UC but reduce CD risk. Moreover, we found individual disease risk loci: TNFSF15 and TNFα to CD and HLA-B*5201, and NFKBIL1 to UC. The genetic risk of HLA was substantially high (odds ratios ranged from 1.54 to 2.69) while that of common susceptibility loci to IBD was modest (odds ratio ranged from 1.13 to 1.24).

CONCLUSIONS

Results indicate that Japanese IBD susceptibility loci identified by the meta-analysis are closely associated with the HLA regions.

Genetic polymorphisms in the IL-18 gene and ulcerative colitis risk: a meta-analysis

This meta-analysis was performed to evaluate the relationships between genetic polymorphisms in the IL-18 gene and ulcerative colitis (UC) risk. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) with their 95% confidence intervals (95% CI) were calculated. Eight case-control studies with a total of 1000 UC cases and 1392 healthy subjects met the inclusion criteria. Six common polymorphisms in the IL-18 gene were evaluated, including rs1946518 A>C, rs187238 G>C, rs917997 G>A, Codon35, rs1946519 C>A, and rs360718 A>C. The results of our meta-analysis suggest that the IL-18 rs1946518 (allele model: OR=1.22, 95% CI: 1.01-1.48, p=0.039; dominant model: OR=1.44, 95% CI: 1.01-2.06, p=0.045; respectively), rs187238 (allele model: OR=1.38, 95% CI: 1.19-1.61, p<0.001; dominant model: OR=1.50, 95% CI: 1.03-2.19, p=0.034; respectively), and rs360718 (allele model: OR=2.18, 95% CI: 1.22-3.90, p=0.008) polymorphisms might be strongly correlated with an increased risk of UC. A subgroup analysis was conducted to investigate the effect of ethnicity on an individual's risk of UC. Our results revealed positive significant correlations between IL-18 genetic polymorphisms and an increased risk of UC among Asians (allele model: OR=1.36, 95% CI: 1.16-1.60, p<0.001; dominant model: OR=1.50, 95% CI: 1.14-1.98, p=0.004; respectively) and Africans (allele model: OR=1.45, 95% CI: 1.03-2.05, p=0.034), but not among Caucasians (all p>0.05). Our findings provide convincing evidence that IL-18 genetic polymorphisms may contribute to susceptibility to UC, especially the rs1946518, rs187238, and rs360718 polymorphisms among Asians and Africans.