Genetic analysis of the CD28/CTLA4/ICOS (CELIAC3) region in coeliac disease

Up-regulation of circRNA-0003528 promotes mycobacterium tuberculosis associated macrophage polarization via down-regulating miR-224-5p, miR-324-5p and miR-488-5p and up-regulating CTLA4

Background: In this study, we selected several candidate miRNAs to study their possible relationships with tuberculosis.

Results: The expression of hsa_circ_0003528 was negatively correlated with the expression of miR-224-5p, miR-324-5p, miR-488-5p, miR-587, and miR-668, while the expression of hsa_circ_0003528 was positively correlated with the expression of miR-224-5p, miR-324-5p and miR-488-5p. No evident difference was observed between tuberculosis and healthy control groups in terms of the expression of miR-587 and miR-668.

Conclusion: The findings of this study demonstrated that miR-224-5p, miR-324-5p and miR-488-5p were all ceRNAs of circRNA-0003528 by sponging each other and CTLA4 was found to be a shared target gene of miR-224-5p, miR-324-5p and miR-488-5p. Furthermore, we found that up-regulation of circRNA-0003528 promoted tuberculosis associated macrophage polarization by promoting expression CTLA4, which was mediated by the down-regulation of miR-224-5p, miR-324-5p and miR-488-5p.

Methods: RT-qPCR and Western blot were conducted to observe the expression of hsa_circ_0003528, miRNAs and CTLA4 in different patient and cell groups to establish the potential molecular mechanisms underlying the effect of hsa_circ_0003528 on M1 to M2 macrophage polarization.

Celiac disease in children with atopic dermatitis

Celiac disease (CD) is an autoimmune disorder of the small intestine with highly variable clinical presentation and frequently associated with various immune-mediated diseases. Among these immune-mediated diseases, atopy has been found frequently in individuals with CD. We aimed to study the prevalence of CD in Estonian children with atopic dermatitis (AD), a common multifactorial chronic inflammatory skin disease. We recruited 351 consecutive children with active AD (mean age 5.8 yrs, 57.6% boys) at Tallinn Children's Hospital, Estonia. Sera of all patients were tested for total serum immunoglobulin (Ig) A, for IgA- and IgG-type autoantibodies to tissue transglutaminase (IgA-anti-TG2, IgG-anti-TG2) and to deamidated gliadin peptides (IgA-anti-DGP, IgG-anti-DGP). The diagnosis of CD was confirmed histologically by small intestine biopsy according to the European Society of Paediatric Gastroenterology, Hepatology and Nutrition diagnostic criteria. IgA deficiency was detected in nine patients with AD (2.6%), none of whom had IgG-anti-TG2 or IgG-anti-DGP seropositivity. IgA-anti-TG2 positivity was found in 4 (1.1%), IgG-anti-TG2 positivity in 2 (0.6%), IgA-anti-DGP positivity in 11 (3.1%), and IgG-anti-DGP in 10 (2.8%) patients. Celiac disease was confirmed in five (1.4%) patients with AD (95% confidence interval 0.46, 3.32) and all were histologically characterized as Marsh IIIa-IIIc stages and two presented with silent CD. In AD patients, CD prevalence was more than four times as high as in previously studied randomly selected schoolchildren in Estonia. Two patients with AD diagnosed with CD had no symptoms indicative of CD, in spite of extensive histologic changes in the small intestine mucosa. Therefore our study emphasizes the need for evaluating the cost-effectiveness of screening individuals with AD for CD in time to prevent long-term complications.

Molecular mechanisms of the adaptive, innate and regulatory immune responses in the intestinal mucosa of celiac disease patients

Celiac disease is a complex genetic disorder that affects the small intestine of genetically predisposed individuals when they ingest gluten, a dietary protein. Although several genome screens have been successful in identifying susceptibility loci in celiac disease, the only genetic contributors identified so far are the human leukocyte antigen (HLA)-DQ2/DQ8 molecules. One of the most important aspects in the pathogenesis of celiac disease is the activation of a T-helper 1 immune response, when the antigen-presenting cells that express HLA-DQ2/DQ8 molecules present the toxic gluten peptides to reactive CD4(+) T-cells. Recently, new insights into the activation of an innate immune response have also been described. It is generally accepted that the immune response triggers destruction of the mucosa in the small intestine of celiac disease patients. Hence, the activation of a detrimental immune response in the intestine of celiac disease patients appears to be key in the initiation and progression of the disease. This review summarizes the immunologic pathways that have been studied in celiac disease thus far, and will point to new potential candidate genes and pathways involved in the etiopathogenesis of celiac disease, which should lead to novel alternatives for diagnosis and treatment.

Association of CTLA-4 gene polymorphism with end-stage renal disease and renal allograft outcome

Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is upregulated in effector-T-cells after activation that may alter signal transduction and subsequently cytokine production. The present study was designed to investigate the impact of CTLA-4+49 A>G (rs231775), -318 C>T (rs5742909), -658 C>T (rs11571317), -1147 C>T (rs16840252), -1661 A>G (rs4553808), +6230 A>G (rs3087243) SNPs, and microsatellite (AT)n repeat polymorphism among end-stage renal disease (ESRD), acute allograft rejection (AR), and delayed graft function (DGF) cases. In this regard, 350 ESRD patients and 350 controls were included. Polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis method was used for genotyping of CTLA-4 SNPs, while PCR-polyacrylamide gel electrophoresis method was adopted for studying CTLA4 (AT)n polymorphism. The mutant genotype GG of CTLA-4+49A>G,+6230 A>G, and longer alleles of (AT)n repeats polymorphisms were risk associated with ESRD, AR, and DGF cases. The distribution of haplotype+49G:+6230G and GCTTGG (constructed by using 6 studied SNPs) showed risk association for ESRD, DGF, and AR cases. Further, linkage analysis demonstrated strong to moderate linkage disequilibrium in our study populations. The meta-analysis also revealed risk associations for AR cases against GG genotype of CTLA-4+49A>G SNP, while CTLA-4 -318C>T polymorphism showed no correlation against TT genotype among AR cases. Subsequently, no correlation was established against the CTLA-4 -318C>T, -658 C>T, -1147 C>T, and -1661 A>G SNPs in the promoter region. Survival analysis revealed risk associations against GG genotype of CTLA-4+49A>G, +6230 A>G SNP's with overall survival (OS), and higher hazard for the OS. These results suggested that CTLA-4 variants might be involved in susceptibility to ESRD, AR, and DGF.

A multi-factorial genetic model for prognostic assessment of high risk melanoma patients receiving adjuvant interferon

Purpose

IFNa was the first cytokine to demonstrate anti-tumor activity in advanced melanoma. Despite the ability of high-dose IFNa reducing relapse and mortality by up to 33%, large majority of patients experience side effects and toxicity which outweigh the benefits. The current study attempts to identify genetic markers likely to be associated with benefit from IFN-a2b treatment and predictive for survival.

Experimental design

We tested the association of variants in FOXP3 microsatellites, CTLA4 SNPs and HLA genotype in 284 melanoma patients and their association with prognosis and survival of melanoma patients who received IFNa adjuvant therapy.

Results

Univariate survival analysis suggested that patients bearing either the DRB1*15 or HLA-Cw7 allele suffered worse OS while patients bearing either HLA-Cw6 or HLA-B44 enjoyed better OS. DRB1*15 positive patients suffered also worse RFS and conversely HLA-Cw6 positive patients had better RFS. Multivariate analysis revealed that a five-marker genotyping signature was prognostic of OS independent of disease stage. In the multivariate Cox regression model, HLA-B38 (p = 0.021), HLA-C15 (p = 0.025), HLA-C3 (p = 0.014), DRB1*15 (p = 0.005) and CT60*G/G (0.081) were significantly associated with OS with risk ratio of 0.097 (95% CI, 0.013–0.709), 0.387 (95% CI, 0.169–0.889), 0.449 (95% CI, 0.237–0.851), 1.948 (95% CI, 1.221–3.109) and 1.484 (95% IC, 0.953–2.312) respectively.

Conclusion

These results suggest that gene polymorphisms relevant to a biological occurrence are more likely to be informative when studied in concert to address potential redundant or conflicting functions that may limit each gene individual contribution. The five markers identified here exemplify this concept though prospective validation in independent cohorts is needed.

Association of CTLA4 gene polymorphisms with susceptibility and pathology correlation to pulmonary tuberculosis in Southern Han Chinese

The cytotoxic T lymphocyte antigen-4 (CTLA4) gene is a key negative regulator of the T lymphocyte immune response. It has been found that CTLA4 +49A>G (rs231775), +6230G>A (rs3087243), and 11430G>A (rs11571319) polymorphisms are associated with susceptibility to many autoimmune diseases, and can down-regulate the inhibition of cellular immune response of CTLA4. Three SNPs in CTLA4 were genotyped by using the PCR and DNA sequencing methods in order to reveal the susceptibility and pathology correlation to pulmonary tuberculosis in Southern Han Chinese. We found that the frequency of CTLA4 +49AG genotype in the pulmonary tuberculosis patients (38.42%) was significantly lower than that of the healthy controls (49.77%), (P(cor)=0.038, OR 0.653, 95% CI 0.436-0.978). But, no associations were found between the other 2 SNPs (+6230G>A, 11430G>A) and tuberculosis (P>0.05). Haplotype analysis showed that the frequency of haplotype AGG in the healthy controls group (6.9%) was significantly higher than the pulmonary tuberculosis patients group (1.4%), (global P=0.005, P(cor)=0.0002, OR 0.183, 95% CI 0.072-0.468). In addition, haplotype GGA was found to be significantly related to tuberculosis with double lung lesion rather than single lung lesion (P(cor)=0.042). This study is the first to report that genetic variants in the CTLA4 gene can be associated with pulmonary tuberculosis in Southern Han Chinese, and CTLA4 +49AG genotype as well as haplotype AGG may reduce the risk of being infected with pulmonary tuberculosis. The GGA haplotype was related to tuberculosis with double lung lesion, which provides a new experimental basis to clarify the pathogenesis of pulmonary tuberculosis.

Interaction between CTLA4 gene and IBD5 locus in Hungarian Crohn's disease patients

BACKGROUNDS AND AIMS

The IGR2198a_1 and IGR2096a_1 variants of the IBD5 region were found to be associated with Crohn's disease (CD) in the Hungarian population, while IGR2230a_1 does not seem to confer risk for the disease. In the present study, our aim was to investigate the statistical interaction of these three IBD5 polymorphisms with the +49 A/G substitution within the cytotoxic T lymphocyte antigen-4 (CTLA4) gene, detected previously as neutral gene variant in Hungarian IBD patients.

METHODS

A total of 305 unrelated subjects with CD and 310 healthy controls were genotyped with PCR-RFLP methods.

RESULTS

In contrast with single gene effects, after genotype stratification, the IGR2198a_1 C and IGR2096a_1 T variants were found to confer susceptibility only in subjects with CTLA4 +49 AA genotype (P = 0.008; OR = 1.86 and P = 0.016; OR = 1.74, respectively), for IGR2230a_1 no such effect on disease risk could be demonstrated.

CONCLUSION

Analysis of specific genotype combinations unfolded a possible association between the CTLA4 +49 A/G substitution and two of the observed IBD5 variants with respect to disease risk.

Polymorphisms in the CD28/CTLA4/ICOS genes: role in malignant melanoma susceptibility and prognosis?

The appearance of vitiligo and spontaneous regression of the primary lesion in melanoma patients illustrate a relationship between tumor immunity and autoimmunity. T lymphocytes play a major role both in tumor immunity and autoimmunity. CD28, Cytotoxic T lymphocyte antigen 4 (CTLA4) and inducible costimulator (ICOS) molecules are important secondary signal molecules in the T lymphocyte activation. Single nucleotide polymorphisms (SNPs) in the CD28/CTLA4/ICOS gene region were reported to be associated with several autoimmune diseases including, type-1 diabetes, SLE, autoimmune thyroid diseases and celiac disease. In this study, we investigated the association of SNPs in the CD28, CTLA4 and ICOS genes with the risk of melanoma. We also assessed the prognostic effect of the different polymorphisms in melanoma patients. Twenty-four tagging SNPs across the three genes and four additional SNPs were genotyped in a cohort of 763 German melanoma patients and 734 healthy German controls. Influence on prognosis was determined in 587 melanoma cases belonging to stage I or II of the disease. In general, no differences in genotype or allele frequencies were detected between melanoma patients and controls. However, the variant alleles for two polymorphisms in the CD28 gene were differentially distributed in cases and controls. Similarly no association of any polymorphism with prognosis, except for the rs3181098 polymorphism in the CD28 gene, was observed. In addition, individuals with AA genotype for rs11571323 polymorphism in the ICOS gene showed reduced overall survival. However, keeping in view the correction for multiple hypothesis testing our results suggest that the polymorphisms in the CD28, CTLA4 and ICOS genes at least do not modulate risk of melanoma and nor do those influence the disease prognosis in the investigated population.

Polymorphisms of the CTLA4 gene and kidney transplant rejection in Korean patients

Cytotoxic T-lymphocyte-associated protein 4 (CTLA4) is a member of the immunoglobulin superfamily. CTLA4, which binds to B7 molecules on antigen- presenting cells, is expressed on activated T cells, thereby delivering negative signals that down-regulate T-cell proliferation and cytokine production. Consequently, CTLA4 may be a good candidate gene to evaluate in kidney transplantation rejection. In this study, we investigated whether polymorphisms of the CTLA4 gene were associated with susceptibility to kidney transplantation rejection. We genotyped three selected SNPs in the CTLA4 gene using direct sequencing in 325 renal transplant recipients. Of the SNPs examined, one (rs231775) showed a statistical association with late acute rejection (p=0.026, odds ratio (OR)=0.48, 95% confidence interval (CI)=0.23-0.93 in the dominant model). Also, the frequency of the G allele (rs231775) was higher in late acute rejection patients (p=0.013, OR=2.02, 95% CI=1.15-3.52). One CTLA4 gene polymorphism was associated with susceptibility to late acute rejection in kidney transplantation in Korean patients.

Association between genotypes and phenotypes in coeliac disease

BACKGROUND

Coeliac disease (CD) is a genetically driven immunological intolerance to dietary gluten with a wide range of clinical presentations. The aim of this study was to investigate the heritability of the phenotype in CD and the influence on the phenotype of different genes associated with the disease.

PATIENTS AND METHODS

One hundred and seven families with at least 2 siblings with CD were collected. The patients were grouped in symptom grades on the basis of the clinical presentation, the age at diagnosis, and sex. Stratification analyses of the human leucocyte antigen-DQA1 and human leucocyte antigen-DQB1 genotypes, the CTLA4 +49A/G polymorphism, the CTLA4 haplotype MH30*G:-1147*T:+49*A:CT60*G:CT61*A, and the 5q31-33 loci were done.

RESULTS

The heritability of the phenotype was estimated to be 0.45. Significant association and linkage was found between the clinical presentation and the CTLA4 +49A/G polymorphism but not for the other genotypes. No correlation was found between genotypes and age at diagnosis or sex.

CONCLUSIONS

Our results indicate that the heritability is determiner of the phenotype in CD. The CTLA4 +49A/G polymorphism is correlated to the clinical presentation: the AA genotype is associated with clinically silent disease.

Association of CTLA-4 gene polymorphism with Graves' disease and ophthalmopathy in Iranian patients

BACKGROUND

The cytotoxic T lymphocyte associated antigen-4 (CTLA-4) gene, is one of the candidate genes for susceptibility to Graves' disease. This study aimed to investigate the association of Graves' disease and Graves' ophthalmopathy with polymorphisms at position +49 in exon 1 and positions -318 and -1147 in the promoter region of CTLA-4 gene in Iranian patients.

METHODS

A total of 205 unrelated Iranian patients with Graves' disease who were referred to the outpatient endocrine clinic of a large university general hospital and 103 sex-matched healthy controls were included in this study. Venous blood was obtained, genomic DNA was extracted by a salting out method, and the polymorphisms at positions +49, -318 and -1147 of the CTLA-4 gene were determined using the PCR-restriction fragment length polymorphism method (PCR-RFLP). Genotype and allele frequencies were determined.

RESULTS

The frequency of the G allele at position +49 was significantly higher in patients with Graves' disease than in the control group (27.1% vs. 15.1%, OR=2.096, 95%CI=1.350-3.253 and p<0.01). Significant trends were not seen for the other two polymorphisms studied. In patients with ophthalmopathy, the frequency of the G allele at position +49 was higher than in those without ophthalmopathy (33.8% vs. 20.0%, OR=2.043, 95%CI=1.304-3.202 and p<0.01).

CONCLUSION

The results of this study suggest that the G allele at position +49 in exon1 of the CTLA-4 gene is associated with Graves' disease and Graves' ophthalmopathy in Iranian patients.

A common CTLA4 polymorphism confers susceptibility to autoimmune thyroid disease in celiac children

BACKGROUND

Cytotoxic T-lymphocyte-associated protein 4 (CTLA4) is a strong candidate gene in autoimmunity susceptibility. In particular, the CTLA4 CT60 A/G dimorphism has been associated with celiac disease (CD) and was reported to be strongly associated with autoimmune thyroid disease (AITD).

AIMS

This study aimed to investigate the possible influences of the CTLA4 CT60 A/G polymorphism in the susceptibility of Italian children to CD and in the predisposition to develop AITD in children with CD.

PATIENTS AND METHODS

We genotyped 317 Italian celiac children, including 44 patients (13.9%) who developed AITD after CD diagnosis and 350 controls.

RESULTS

The CTLA4 CT60 GG genotype distribution did not show any significant difference between children with CD and control population (p=0.4). On the contrary, the frequency of the GG genotype was significantly higher in patients with CD complicated with AITD than in control subjects (p=0.002) and CD patients without AITD (p=0.02).

CONCLUSION

Our data show a significant effect of the CTLA4 CT60G allele at the homozygous state on the risk of developing AITD in children with CD and suggest that the reported association of the CTLA4 CT60 A/G polymorphism with CD is limited to the subgroup of patients who are or will be complicated with AITD.

Prevalence of celiac disease in Turkish children with autoimmune thyroiditis

The close association between celiac disease (CD) and autoimmune disorders is well documented in adult and pediatric patients. The aim of this study is to determine the prevalence of CD in Turkish children with autoimmune thyroiditis (AT). Sera from 101 children with AT (11 boys and 90 girls, from 2 to 18 years of age; mean age 12.28 +/- 3.26 years) and 103 healthy children (46 boys and 57 girls, from 3.5 to 17 years of age; mean age 12.18 +/- 3.11 years) were screened for CD using the IgA anti-tissue transglutaminase (IgA anti-tTG) antibody and total serum IgA. Small intestinal biopsy was offered to all antibody-positive patients. IgA anti-tTG was positive in eight children (7.9%) with AT. None of the serum samples of healthy children were positive for IgA anti-tTG antibody. Selective IgA deficiency was not detected in patients or controls. Intestinal biopsy was accepted by seven patients. In five patients (4.9%), subtotal villous atrophy was found. These findings indicate that the prevalence of CD is higher in Turkish children with AT than in healthy controls. Routine screening for CD should be performed in children with AT.

Association of the CTLA-4 gene with Vogt-Koyanagi-Harada syndrome

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), a critical negative regulator of the T cell response, has been shown to be associated with a variety of autoimmune diseases. In this study, we investigated the association of CTLA-4 gene polymorphisms (- 1661A/G; - 318C/T; + 49G/A, and CT60) with Vogt-Koyanagi-Harada (VKH) syndrome in Chinese Han patients and normal controls. The results showed that the frequency of the G allele at the + 49 site was significantly higher in VKH patients than that observed in healthy controls (71.6% versus 62.8%, P = 0.0046, Pc = 0.037). Three haplotypes were identified from the four SNPs. The frequency of haplotype - 1661A:- 318C:+ 49G:CT60G, the most prevalent haplotype both in patients and controls, was significantly higher in patients than that in controls (70.1% versus 60.0%, P= 0.0013, n= 16, Pc = 0.021). These results suggest that CTLA-4 genetic polymorphisms are associated with the susceptibility to VKH syndrome.

Multiple sclerosis and the CTLA4 autoimmunity polymorphism CT60: no association in patients from Germany, Hungary and Poland

Polymorphisms in the CTLA4 gene region have been associated with susceptibility to autoimmune diseases. The recently described single nucleotide polymorphism CT60, located in the 3' untranslated region of CTLA4 is associated with Graves' disease, thyroiditis, autoimmune diabetes and other autoimmune diseases. A case-control association study was conducted in German, Hungarian and Polish multiple sclerosis (MS) patients and regional control individuals for the CTLA4 CT60 and + 49A/G polymorphisms. No significant association of these polymorphisms or respective haplotypes with MS was found. No association of CT60 genotypes with T cell expression of ICOS and CTLA-4 after in vitro stimulation was detected. Multiple Sclerosis 2008; 14: 153—158. http://msj.sagepub.com

Genetic analyses of celiac disease in a Spanish population confirm association with CELIAC3 but not with CELIAC4

Genetic predisposition to celiac disease (CD) is determined primarily by the human leukocyte antigen (HLA) genes (CELIAC1 region; 6p21), although many loci are involved in disease susceptibility. First, we have analysed a large series of CD patients from the Spanish Mediterranean region who had previously been characterised for the HLA complex. We have investigated how relevant regions contribute to CD susceptibility: CELIAC3 (CD28/CTLA4/ICOS region on 2q33) and CELIAC4 (19p13) as well as the tumour necrosis factor alpha (TNF-alpha) and the linfotoxin loci by case-control and association analyses. We highlight the association with the +49*A allele of cytotoxic T-lymphocyte-associated antigen 4 locus (P = 0.01), and the -308*A of TNF-alpha locus (P = 0.0008) in DQ2 individuals, although an independent role for TNF-alpha as risk factor has not been proven. Moreover, we do not confirm the association with the CELIAC4 region polymorphisms described in other populations.

Searching for genes influencing a complex disease: the case of coeliac disease

Recently, a few genes have been reported to be causative in inflammatory diseases. Still, we are waiting for the vast majority to be discovered. New tools for genotyping and statistical analysis have been developed and emphasis has been put on study design. Coeliac disease (CD) is a disorder, where prolamins in dietary wheat gluten and related proteins from rye or barley are not tolerated. It is one of the most common chronic diseases in humans exceeding a population prevalence of 1%. In this article, we will summarise what is currently known about the genetics influencing CD with the emphasis on the non-HLA genetic component. We will discuss some difficulties when searching for susceptibility genes in disorders with complex inheritance patterns.

Associated autoantibodies in celiac disease

Celiac disease (CD) is a life-long inflammatory autoimmune condition of the gastrointestinal tract affecting genetically susceptible individuals. Several autoimmune disorders are more prevalent in patients and their close relatives and that risk is gluten exposure duration related. The most frequent reported CD associated conditions are type 1 diabetes mellitus and autoimmune thyroiditis. Associated autoimmune antibodies are frequent in CD and their first-degree relatives, spanning anti-endocrine, anti-gastrointestinal, anti-nuclear, anti-cytoskeleton and anti-neurological antibodies. More specifically, antibodies against thyroid and the endocrine pancreas, anti-gastric and liver, anti-nuclear constituents, anti-reticulin, actin, smooth muscle, calreticulin, desmin, collagens and bone, anti-brain, ganglioside, neuronal and blood vessel were described in sera of the patients in numerous studies. The common immunogenetic theories for the above associations are: sharing common HLA and non-HLA genes, antigenic mimicry, damage-induced neoantigen exposure, altered intestinal permeability, idiotype network dysregulation and epitope spreading. The CD associated autoantibodies enigma, being an epiphenomenon or pathogenic, remains unresolved and presents a challenging area for future research.

FOXP3 polymorphisms in type 1 diabetes and coeliac disease

The FOXP3 gene encodes a transcription factor thought to be essential for the development and function of T regulatory cells. Two previous studies have tested common polymorphisms in FOXP3 for association with type 1 diabetes (T1D) with conflicting results. The aim of our study was to see whether there is any evidence of association between the FOXP3 polymorphisms previously reported to be associated with T1D, in a Caucasian population regarding T1D and coeliac disease (CD). We further looked for evidence of interaction between FOXP3 polymorphisms and HLA-DR3 in conferring susceptibility to T1D. Initially, we analysed two microsatellites in the FOXP3 gene in 363 T1D nuclear families. Our results indicated an association between FOXP3 and T1D (global p=0.004) and a possible interaction between FOXP3 and the HLA-DR3-DQ2 susceptibility haplotype. We then genotyped an additional independent set of 826 T1D patients and 1459 controls as well as one CD dataset consisting of 325 families. A similar tendency was revealed in the CD family material (pnc=0.055 for the associated allele). On the other hand, we were unable to reproduce our initial findings in the T1D case-control dataset (global p=0.6). Our results suggest that the tested FOXP3 markers do not have any major impact on susceptibility for these diseases.

Influence of CTLA4 haplotypes on susceptibility and some extraglandular manifestations in primary Sjögren's syndrome

OBJECTIVE

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a key negative regulator of the T cell immune response, and the CTLA4 gene is highly polymorphic. Many positive associations between CTLA4 single-nucleotide polymorphisms (SNPs) and various autoimmune diseases have been identified. Two CTLA4 SNPs that are important relative to genetic susceptibility in human autoimmune diseases are the +49GA polymorphism in exon 1 and the CT60A/G polymorphism in the 3'-untranslated region. Using these 2 polymorphisms as markers, we investigated possible genetic associations of CTLA4 in Australian patients with primary Sjögren's syndrome.

METHODS

One hundred eleven Australian Caucasian patients with primary SS and 156 population-based controls were genotyped for CTLA4 by polymerase chain reaction-restriction fragment length polymorphism methods, using the restriction enzymes BseXI (+49G/A) and HpyCh4 IV (CT60).

RESULTS

The CT60 and +49G/A SNPs were in strong linkage disequilibrium, and only 3 haplotypes were observed. Significant differences in the haplotype frequencies between patients with primary SS and controls (P = 0.032) were observed, with susceptibility to primary SS associated with both the +49A;CT60A haplotype and the +49A;CT60G haplotype, whereas the +49G;CT60G haplotype was protective against primary SS. The +49A;CT60G haplotype association was predominantly with Ro/La autoantibody-positive primary SS, and the dose of this haplotype influenced the severity of daytime sleepiness (P = 0.036). The +49A;CT60A haplotype appeared to be protective against the development of Raynaud's phenomenon in patients with primary SS (odds ratio 0.49, 95% confidence interval 0.27-0.91).

CONCLUSION

The CTLA4 +49G/A and CT60 haplotypes are associated with susceptibility to primary SS and with some extraglandular manifestations of the disease.

Association of T-cell regulatory gene polymorphisms with susceptibility to gastric mucosa-associated lymphoid tissue lymphoma

PURPOSE

Helicobacter pylori infection and host susceptibility interact to develop gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and activation of specific T cells might play a crucial role in this process. Recent investigations show that the CTLA4, CD28, and ICOS genes are located on chromosome 2q33 and their polymorphisms confer susceptibility to infectious and immune diseases through deregulation of T-cell stimulation. We aimed to determine the role of CTLA4, CD28, and ICOS polymorphisms in gastric MALT lymphoma.

PATIENTS AND METHODS

Genotyping for CTLA4 (49 A/G, -318 C/T, and CT60 A/G), CD28 (IVS3+ 17T/C), and ICOS (c.602 A/C and c.1624C/T) was performed for 62 patients with gastric MALT lymphoma and compared with 250 unrelated healthy controls.

RESULTS

H pylori infection was significantly higher in patients with gastric MALT lymphoma (90.3%) compared with controls (66.4%; P < .001). The CTLA4 -318 C/T genotype was associated with a lower risk of developing gastric MALT lymphoma (odds ratio [OR] = 0.3; P = .022), whereas CTLA4 49 G/G genotype was linked to a higher risk (OR = 4.1; P = .044). In patients with H pylori infection, CTLA4 49 G/G genotype was associated with an even higher risk (OR = 6.4; P = .047). Carriage of the tightly linked -318C -49G haplotype conferred a four-fold higher susceptibility to MALT lymphoma (OR = 4.2; P = .042). Complete remission after H pylori eradication was related to tumor stage but not to genotypes or haplotypes.

CONCLUSION

These results indicate a genetic link of CTLA4 gene polymorphisms to development of gastric MALT lymphoma and indirectly support the crucial role of host activated T cells in the MALT lymphomagenesis.

The downstream modulator of interferon-γ, STAT1 is not genetically associated to the Dutch coeliac disease population

Coeliac disease (CD) is a complex genetic disorder. Its etiology is owing to multiple genes and environmental factors, such as gluten. The first event in the pathogenesis of CD after the ingestion of gluten is the activation of a Th1 immune response that leads to villous atrophy. Although this immune response seems crucial to the disease's development, only the HLA-DQ2/DQ8 genes have been identified as causative immune genes related to CD. Recently, the activation of the transcription factor STAT1 and changes in its expression levels have confirmed the participation of the Janus kinase-signal transducer and activator of transcription pathway in CD. Furthermore, as the STAT-1 gene is a positional candidate located in the CELIAC3 locus on chromosome 2, we speculate that alterations in this gene could be primarily responsible for the aberrant immune response that characterizes CD. Based on this functional and genetic evidence, we investigated the primary contribution of STAT-1 to CD. We performed a comprehensive genetic association study using five tag SNPs fully covering the STAT-1 gene in a Dutch cohort of 355 independent CD cases and 360 healthy controls. Neither the alleles, nor the genotypes in the case-control genetic association studies, nor the haplotype analysis showed any association to the STAT-1 gene in the Dutch CD population. Our results do not point to a primary involvement of the STAT-1 gene in the Dutch CD population.

Advances in celiac disease

PURPOSE OF REVIEW

This article primarily aims to review critically research in all aspects of celiac disease over the last year. As always, there has been a wealth of relevant papers.

RECENT FINDINGS

The role of genetics in disease susceptibility is slowly becoming more clearly defined and a more detailed understanding of the disease processes at the molecular level is paving the way towards the development of specific targeted therapies.

SUMMARY

Despite recent advances in our understanding of celiac disease, the gluten-free diet remains the only current viable therapy and even with advances in serological tests and markers, the duodenal biopsy remains the gold standard for diagnosis and monitoring of the response to therapy.

The functional genetic variation in the PTPN22 gene has a negligible effect on the susceptibility to develop inflammatory bowel disease

The aim of this study was to assess the possible association between the protein tyrosine phosphatase non-receptor 22 (PTPN22) gene 1858C-->T (rs2476601, encoding R620W) polymorphism and inflammatory bowel disease (IBD). Our study population consisted of 1113 IBD [544 ulcerative colitis (UC) and 569 Crohn's disease (CD)] patients and 812 healthy subjects. All the individuals were of Spanish white origin. Genotyping of the PTPN22 gene 1858C-->T polymorphism was performed by real time polymerase chain reaction technology, using TaqMan 5'-allelic discrimination assay. The frequency of the PTPN22 1858T allele in healthy subjects was 6.2% compared with 6.7% in the UC patients and 5.1% in Crohn's patients. No statistically significant differences were observed when the PTPN22 1858C-->T allele and genotype distribution among CD patients, UC patients and healthy controls were compared. These results indicate that the PTPN22 1858C-->T polymorphism does not appear to play a major role in IBD predisposition in our population.

Haplotypes in the CTLA4 region are associated with coeliac disease in the Irish population

Chromosomal region 2q33 encodes the immune regulatory genes, CTLA4, ICOS and CD28, which are involved in regulation of T-cell activity and has been studied as a candidate gene locus in autoimmune diseases, including coeliac disease (CD). We have investigated whether an association exists between this region and CD in the Irish population using a comprehensive analysis for genetic variation. Using a haplotype-tagging approach, this gene cluster was investigated for disease association in a case-control study comprising 394 CD patients and 421 ethnically matched healthy controls. Several SNPs, including CTLA4_CT60, showed association with disease; however, after correction for multiple-testing, CTLA4-658C/T was the only polymorphism found to show significant association with disease when allele, genotype, or carrier status frequency were analysed (carrier status (Allele C), P = 0.0016). Haplotype analysis revealed a haplotype incorporating the CD28/CTLA4 and two 5' ICOS polymorphisms to be significantly associated with disease (patients 24.1%; controls 31.5%; P = 0.035), as was a shorter haplotype composed of the CTLA4 markers only (30.9 vs 34.9%; P = 0.042). The extended haplotype incorporating CD28/CTLA4 and 5' ICOS is more strongly associated with disease than haplotypes of individual genes. This suggests a causal variant associated with this haplotype may be associated with disease in this population.

Lack of association with the CD28/CTLA4/ICOS gene region among Norwegian multiple sclerosis patients

Chromosome region 2q33 encodes several regulators of the immune system, among these the CD28, CTLA4, and ICOS molecules. Involvement of these genes in multiple sclerosis (MS) is not yet clear. We investigated six microsatellites and three SNPs in a relatively large and clinically well characterised Norwegian MS cohort. No associations were observed for any of the markers analysed in 575 MS patients and 551 controls. Associations were neither found when stratifying the material for the HLA-DRB1*1501, DQB1*0602 haplotype, gender, age at onset, disease course nor familial aggregation. In conclusion, this study could not confirm association with the CD28/CTLA4/ICOS gene region.

CTLA4 is differentially associated with autoimmune diseases in the Dutch population

Cytotoxic T lymphocyte-associated antigen 4 (CTLA4) is an important negative regulator of T-cell response and its genetic association with type 1 diabetes (T1D) has recently been demonstrated. The frequent co-association of autoimmune diseases (AID) and the implication from multiple genome scans that the CTLA4 gene region is a general autoimmune region, led us to study the role of CTLA4 in independent cohorts of T1D, coeliac disease (CD) and rheumatoid arthritis (RA) patients. We present independent data that confirm the association of CTLA4 in Dutch patients with juvenile onset T1D and show differential association of CTLA4 with CD and RA. The CTLA4 gene polymorphisms were tested for association in 350 T1D, 310 CD, 520 RA patients and 900 controls. In addition, 218 families were tested by the transmission disequilibrium test (TDT). T1D patients showed the highest association with the MH30*G: -1147*C: +49*G: CT60*G: JO37_3*G (haplotype 2) in both a case/control cohort (P=0.002, OR=1.42) and by TDT (P=0.02, OR=1.43). In contrast, this haplotype showed no association in the RA and CD cohorts. However, we observed an increased frequency of the MH30*G: -1147*T: +49*A: CT60*G: JO37_3*A (haplotype 3) in the CD patients diagnosed at a young age (OR=1.6, P=0.026, P (c)=0.052). Furthermore, when T1D and CD patients were stratified based on the HLA risk, the T1D susceptible CTLA4 haplotype 2 was over-represented in the high HLA-risk T1D and CD groups. In conclusion, we confirmed association between CTLA4 haplotype 2 and T1D in the Dutch population. Association with another CTLA4 haplotype (haplotype 3) was confirmed for CD, but only in those patients who had an early age of expression. No effect was found between RA and CTLA4. The association of the CTLA4 haplotype 2 with the high-risk HLA genotype in T1D and CD, which share DQ2 as the one of high-risk alleles, might provide a clue to understanding the common genetic background of AID.