Celiac disease and TNF promoter polymorphisms

Inter- and intrabreed diversity of the major histocompatibility complex (MHC) in primitive and draft horse breeds

Background

Polymorphism of major histocompatibility complex (MHC) genes ensures effective immune responses against a wide array of pathogens. However, artificial selection, as performed in the case of domestic animals, may influence MHC diversity. Here, we investigate and compare the MHC diversity of three populations of horses, for which different breeding policies were applied, to evaluate the impact of artificial selection and the environment on MHC polymorphism.

Methods

Samples of DNA were taken from 100 Polish draft horses, 38 stabled Konik Polski horses and 32 semiferal Konik Polski horses. MHC alleles and haplotype diversity within and between these populations of horses was estimated from 11 MHC microsatellite loci.

Results

MHC diversity measured based on allelic richness, observed heterozygosity, expected heterozygosity and polymorphism content was similar across the MHC microsatellite loci in all three populations. The highest expected heterozygosity was detected in semiferal primitive horses (He = 0.74), while the lowest was calculated for draft horses (He = 0.65). In total, 203 haplotypes were determined (111 in Polish draft horses, 43 in semiferal Konik Polski horses and 49 in stabled Konik Polski horses), and four haplotypes were shared between the two populations of Koniks. None of these haplotypes were present in any of the previously investigated horse breeds. Intra-MHC recombination events were detected in all three populations. However, the population of semiferal Konik horses showed the highest recombination frequency among the three horse populations. In addition, three recombination events were detected.

Conclusions

These results showed that despite the different breeding policies, the MHC allele and haplotype diversity was similarly high in all three horse populations. Nevertheless, the proportion of new haplotypes in the offspring was the highest in semiferal Konik Polski horses, which indicates the influence of the environment on MHC diversity in horses. Thus, we speculate that the genetic makeup of the domestic horse MHC might be more strongly influenced by the environment than by artificial selection. Moreover, intra-MHC conversion, insertion, and deletion and intra-MHC recombination may be proposed as mechanisms underlying the generation of new MHC haplotypes in horses.

ASSOCIATION OF TNF- α-308G>A POLYMORPHISM WITH SUSCEPTIBILITY TO CELIAC DISEASE: A SYSTEMATIC REVIEW AND META-ANALYSIS

BACKGROUND

There is increasing evidence to show that TNF-α -308G>A polymorphism may be a risk factor for celiac disease, but the results are inconsistent.

OBJECTIVE

Thus, we aimed to perform a meta-analysis involving published studies up to January 2019 to elucidate the association.

METHODS

To assess the effect of TNF-α -308G>A polymorphism on celiac disease susceptibility, we searched PubMed, ISI Web of Knowledge, Chinese National Knowledge Infrastructure (CNKI) databases to identify eligible studies, without restriction. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the susceptibility to celiac disease.

RESULTS

A total of 11 studies with 1147 cases and 1774 controls were selected for this meta-analysis. The pooled results indicated that TNF-α -308G>A polymorphism was associated with increased risk of celiac disease (A vs G: OR=2.077, 95% CI=1.468-2.939, P=≤0.001; AA vs GG: OR=8.512, 95% CI=3.740-19.373, P=≤0.001; AA+AG vs GG: OR=1.869, 95% CI=1.161-3.008, P=0.010; and AA+AG vs GG: OR=4.773, 95% CI=3.181-7.162, P≤0.001). Subgroup analysis by ethnicity also revealed significant association in Caucasians. In addition, there was a significant association between TNF-α -308G>A polymorphism and celiac disease risk in Italy, Spain and PCR-FRLP group studies.

CONCLUSION

Our meta-analysis suggests that the TNF-α -308G>A polymorphism plays an important role in celiac disease susceptibility. However, our results are still needed to strengthen by further studies in different ethnicities and larger sample sizes.

Association of celiac disease genetic markers with reproduction disorders

Background: Numerous studies have shown a link between genes involved in the immune response and infertility and miscarriage. The most significant associations have been established for the cytokine genes (IL1B, IL6, IL10, IL18), chemokine genes (CXCL9, CXCL10, CXCL11), and genes of the major histocompatibility complex HLA II class (DQA1, DQB1, DRB1). HLA genes are associated with celiac disease, a genetically determined autoimmune disorder, where male and female reproduction impairment is one of the symptoms. Aim: To assess the prevalence of polymorphic variants of the immune response genes (HLA: DQA1 DQB1, DRB1; TNF, IL10, CXCL10) in patients with reproduction disorders. Materials and methods: This pilot study involved assessment of the following gene polymorphisms: IL10 (rs1800872), TNF (rs1800629), CXCL10 (rs4386624), and HLA class II (DQA1, DQB1, DRB1) in couples (n = 220) with reproduction disorders (infertility and miscarriage). Genotyping was performed by real-time polymerase chain reaction (PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. The genotypes and alleles population data were used for comparison with the studied variants of the genes IL10 (rs1800872), TNF (rs1800629), and CXCL10 (rs4386624). Differences in the prevalence of alleles and genotypes were assessed by χ2 test. The differences were considered significant at p < 0.05. Haplotype diversity was calculated by the Arlequin software, version 3.5.x. Results: Compared to the populational data, there was significant re-distribution of the genotypes and alleles to the TNF gene (rs1800629) variant in men with impaired reproductive functions. No differences were found for other gene variants studied. The frequency of HLA class II gene (DQA1, DQB1, DRB1) haplotypes associated with celiac disease (DQ2 and DQ8) in the study sample was 23.8%. Conclusion: The results indicate the important role of genes associated with celiac disease in the development of reproduction disorders.

The relationship between 174 G/C and -572 G/C of IL-6 gene polymorphisms and susceptibility of celiac disease in the Iranian population

INTRODUCTION

Celiac disease (CD) is a chronic inflammatory intestinal disorder. Different immunological factors, including inflammatory cytokines, may play an important role in disease susceptibility.

AIM

To investigate the relationship between -174G/C and -572G/C gene polymorphisms and the serum level of interleukin 6 (IL-6) and susceptibility to CD in the Iranian population.

MATERIAL AND METHODS

In this case-control study blood samples were collected of 105 patients with CD and 106 healthy subjects randomly in 2016 and evaluated by polymerase chain reaction-restriction fragments length polymorphism (PCR-RFLP) method. A sequence was also used to confirm the results of both polymorphisms. The IL-6 concentration was measured using ELISA.

RESULTS

The results showed a significant relationship between polymorphism -572G in CD patients when compared with control subjects by genotype (p = 0.001) and alleles (p = 0.022), respectively. There was no significant relationship between polymorphism 174G and frequency of genotype, but an association of this polymorphism with the frequency of alleles (p = 0.034), age (p = 0.001), and body mass index (p = 0.003) was seen. The serum level of interleukin-6 was significantly associated only with rs1800796 (p < 0.001).

CONCLUSIONS

The results confirm previous studies in different parts of the world and indicate that IL-6 (572G/C) polymorphism may play a role in susceptibility to CD in the Iranian population.

Response to TNF-α Is Increasing Along with the Progression in Barrett's Esophagus

BACKGROUND AND AIMS

Barrett's esophagus, a metaplasia resulting from a long-standing reflux disease, and its progression to esophageal adenocarcinoma (EAC) are characterized by activation of pro-inflammatory pathways, induced by cytokines.

METHODS

An in vitro cell culture system representing the sequence of squamous epithelium (EPC1 and EPC2), Barrett's metaplasia (CP-A), dysplasia (CP-B) to EAC (OE33 and OE19) was used to investigate TNF-α-mediated induction of interleukin-8 (IL-8).

RESULTS

IL-6 and IL-8 expressions are increasing with the progression of Barrett's esophagus, with the highest expression of both cytokines in the dysplastic cell line CP-B. IL-8 expression in EAC cells was approx. 4.4-fold (OE33) and eightfold (OE19) higher in EAC cells than in squamous epithelium cells (EPC1 and EPC2). The pro-inflammatory cytokine TNF-α increased IL-8 expression in a time-, concentration-, and stage-specific manner. Furthermore, TNF-α changed the EMT marker profile in OE33 cells by decreasing the epithelial marker E-cadherin and increasing the mesenchymal marker vimentin. The anti-inflammatory compound curcumin was able to repress proliferation and to activate apoptosis in both EAC cell lines.

CONCLUSION

The increased basal expression levels of IL-8 with the progression of Barrett's esophagus constrain NFκB activation and its contribution in the manifestation of Barrett's esophagus. An anti-inflammatory compound, such as curcumin, could create an anti-inflammatory microenvironment and thus potentially support an increase chemosensitivity in EAC cells.

The Interaction among Microbiota, Immunity, and Genetic and Dietary Factors Is the Condicio Sine Qua Non Celiac Disease Can Develop

Celiac disease (CD) is an immune-mediated enteropathy, triggered by dietary wheat gluten and similar proteins of barley and rye in genetically susceptible individuals. This is a complex disorder involving both environmental and immune-genetic factors. The major genetic risk factor for CD is determined by HLA-DQ genes. Dysfunction of the innate and adaptive immune systems can conceivably cause impairment of mucosal barrier function and development of localized or systemic inflammatory and autoimmune processes. Exposure to gluten is the main environmental trigger responsible for the signs and symptoms of the disease, but exposure to gluten does not fully explain the manifestation of CD. Thus, both genetic determination and environmental exposure to gluten are necessary for the full manifestation of CD; neither of them is sufficient alone. Epidemiological and clinical data suggest that other environmental factors, including infections, alterations in the intestinal microbiota composition, and early feeding practices, might also play a role in disease development. Thus, this interaction is the condicio sine qua non celiac disease can develop. The breakdown of the interaction among microbiota, innate immunity, and genetic and dietary factors leads to disruption of homeostasis and inflammation; and tissue damage occurs. Focusing attention on this interaction and its breakdown may allow a better understanding of the CD pathogenesis and lead to novel translational avenues for preventing and treating this widespread disease.

TNFA Haplotype Genetic Testing Improves HLA in Estimating the Risk of Celiac Disease in Children

Background

TNF-α and IFN-γ play a role in the development of mucosal damage in celiac disease (CD). Polymorphisms of TNFA and IFNG genes, as well as of the TNFRSF1A gene, encoding the TNF-α receptor 1, might underlie different inter-individual disease susceptibility over a common HLA risk background. The aims of this study were to ascertain whether five SNPs in the TNFA promoter (-1031T>C,-857C>T,-376G>A,-308G>A,-238G>A), sequence variants of the TNFRSF1A gene and IFNG +874A>T polymorphism are associated with CD in a HLA independent manner.

Methods

511 children (244 CD, 267 controls) were genotyped for HLA, TNFA and INFG (Real Time PCR). TNFRSF1A variants were studied (DHPLC and sequence).

Results

Only the rare TNFA-1031C (OR=0.65, 95% CI:0.44-0.95), -857T (OR=0.42, 95% CI:0.27-0.65), -376A (OR=2.25, 95% CI:1.12-4.51) and -308A (OR=4.76, 95% CI:3.12-7.26) alleles were significantly associated with CD. One TNFRSF1A variant was identified (c.625+10A>G, rs1800693), but not associated with CD. The CD-correlated TNFA SNPs resulted in six haplotypes. Two haplotypes were control-associated (CCGG and TTGG) and three were CD-associated (CCAG, TCGA and CCGA). The seventeen inferred haplotype combinations were grouped (A to E) based on their frequencies among CD. Binary logistic regression analysis documented a strong association between CD and HLA (OR for intermediate risk haplotypes=178; 95% CI:24-1317; OR for high risk haplotypes=2752; 95% CI:287-26387), but also an HLA-independent correlation between CD and TNFA haplotype combination groups. The CD risk for patients carrying an intermediate risk HLA haplotype could be sub-stratified by TNFA haplotype combinations.

Conclusion

TNFA promoter haplotypes associate with CD independently from HLA. We suggest that their evaluation might enhance the accuracy in estimating the CD genetic risk.

A single-nucleotide polymorphism in tumor necrosis factor-α (-308 G/A) as a biomarker in chronic pancreatitis

OBJECTIVE

Chronic pancreatitis is a gradual, long-term inflammation of the pancreas that results in alteration of its normal structure and function. The study aims to investigate the role of -308 (G/A) polymorphism of TNF-α gene in chronic pancreatitis.

MATERIAL AND METHODS

A total of 200 subjects were included in this case-control study. A total of 100 in patients admitted in the Gastroenterology Unit of Gandhi Hospital and Osmania General Hospital, Hyderabad were included in the present study. An equal number of healthy control subjects were randomly selected for the study. The genotyping of TNF-α gene was carried out by tetra-primer ARMS PCR followed by gel electrophoresis. The TNF-α levels were assayed by enzyme-linked immunosorbent assay.

RESULTS

A significant variation with respect to the genotypic and allelic distribution in the disease group when compared to control subjects [OR=2.001 (1.33-3.005), p<0.0001**] was observed. Subjects homozygous for the A allele had higher TNF-α levels compared to G allele.

CONCLUSION

The present study revealed a significant association of the TNF-α gene promoter polymorphism with chronic pancreatitis. Thus, TNF-α genotype can be considered as one of the biological markers in the etiology of chronic pancreatitis.

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.

HLA and celiac disease susceptibility: new genetic factors bring open questions about the HLA influence and gene-dosage effects

Celiac disease (CD) is a chronic inflammatory disorder triggered after gluten ingestion in genetically susceptible individuals. The major genetic determinants are HLA-DQA1*05 and HLA-DQB1*02, which encode the DQ2 heterodimer. These alleles are commonly inherited in cis with DRB1*03∶01, which is associated with numerous immune-related disorders, in some cases contributing with a different amount of risk depending on the haplotype context. We aimed at investigating those possible differences involving DRB1*03∶01-carrying haplotypes in CD susceptibility. A family (274 trios) and a case-control sample (369 CD cases/461 controls) were analyzed. DRB1*03∶01-carrying individuals were classified according to the haplotype present (ancestral haplotype (AH) 8.1, AH 18.2 or non-conserved haplotype) after genotyping of HLA-DRB1, -DQA1, -DQB1, -B8, TNF -308, TNF -376 and the TNFa and TNFb microsatellites. We observe that the AH 8.1 confers higher risk than the remaining DRB1*03∶01-carrying haplotypes, and this effect only involves individuals possessing a single copy of DQB1*02. CD risk for these individuals is similar to the one conferred by inherit DQA1*05 and DQB1*02 in trans. It seems that an additional CD susceptibility factor is present in the AH 8.1 but not in other DRB1*03∶01-carrying haplotypes. This factor could be shared with individuals possessing DQ2.5 trans, according to the similar risk observed in those two groups of individuals.

Human leucocyte antigen and TNFalpha polymorphism association in microscopic colitis

OBJECTIVES

Coeliac disease (CD) is common in patients with microscopic colitis (MC). The human leucocyte antigen (HLA)-DR3-DQ2 haplotype is strongly associated with CD, and there is evidence for an association with MC. We analysed the genetic background of MC by assessing the haplotypes of HLA-DR3-DQ2 and HLA-DR4-DQ8. In addition, TNFalpha gene polymorphism (-308) associated with susceptibility to several autoimmune diseases was studied.

METHODS

Eighty patients with MC including 29 with collagenous colitis (CC) and 51 with lymphocytic colitis (LC) were typed for HLA-DR3-DQ2, and HLA-DR4-DQ8 molecule encoding genes using either an allele-specific PCR, or hybridization with sequence-specific oligonucleotides. Duodenal biopsies (N=78) confirmed the diagnosis of CD in 15 (18.8%) patients. TNFalpha(308) alleles were analyzed in 78 patients with MC (27 with CC and 51 with LC). A control group of 3627 patients was used in the HLA study and 178 patients in the TNFalpha study.

RESULTS

HLA-DR3-DQ2 haplotype was more frequent in patients with MC (43.8%) including both subgroups (LC, 44.8%; CC, 43.1%; P<0.001), and MC with CD (86.7%; P<0.001) and without CD (33.3%; P=0.003), compared with the controls (18.1%). Similarly, the TNF2 carrier rate was higher in MC (46.2%; P<0.001) including both CC (44.4%; P=0.031) and LC (47.1%; P=0.001), and both MC patients with CD (66.7%; P=0.001) and without CD (39.3%; P=0.019), compared with the controls (23%).

CONCLUSION

Both CC and LC are associated with the HLA-DR3-DQ2 haplotype and with TNF2 allele carriage. These associations are present also in MC patients without CD. The shared predisposing HLA-DR3-DQ2 haplotype and the high prevalence of CD in patients with MC suggest an epidemiological overlap, and probably some similarities in the pathogenesis of CD and MC.

The simultaneous presence of IL-1B and TNFA two-positions risk haplotypes enhances the susceptibility for celiac disease

To assess the joint contribution of interleukin 1 beta (IL-1B) and tumor necrosis factor alpha (TNFalpha) to the genetic risk of developing celiac disease (CD), we analyzed four biallelic polymorphisms of TNFA and IL-1B genes in 228 patients and 244 healthy controls. The individual contribution of TNFA -308A and IL-1B -511C alleles was weak (OR 1.47 and 1.66, respectively) and was null for TNFA -238 A/G and IL-1B +3953 C/T single nucleotide polymorphisms (SNPs). Due to the potential linkage disequilibrium between TNFA, human leukocyte antigen (HLA) -DQA1 and HLA-DQB1 genes, only individuals carrying DQ2 antigen (DQ2-positive) were considered to perform haplotype analyses. Two-position risk haplotypes were first defined by the combined presence of -511C and +3953T alleles for IL-1B (OR 9.402) or -308A and -238A alleles for TNFA (OR 15.389). The TNFA/IL-1B combined haplotype-stratified association analysis showed that the simultaneous presence of TNFA risk and IL-1B non-risk haplotypes (OR 13.32) but not TNFA non-risk and IL-1B risk haplotypes (OR 0.71) is associated with CD. Interestingly, our data suggest that the coexistence of both risk haplotypes seems to work synergistically (OR 29.59), which enhances the risk of developing CD.

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.

Polymorphisms of the TNF-alpha gene and risk of celiac disease in T1DM children

BACKGROUND

Type 1 diabetes mellitus (T1DM) and celiac disease (CD) frequently occur together. Previous reports suggested that the (-308)A variant of the tumor necrosis factor-alpha (TNF-alpha) gene is associated either with T1DM or with CD. The aim of our study was to determine whether (-308)A and (-238)A allelic variants of the TNF-alpha gene might have any impact on the risk of CD in T1DM children.

METHODS

Three hundred and one T1DM children were enrolled to the study. The presence of CD was screened with IgA endomysial antibodies (EMA) test. Jejunal biopsy was performed to confirm CD. TNF-alpha-308 and -238 genetic variants were tested using the method of restriction fragment length polymorphism.

RESULTS

The prevalence of CD in the enrolled diabetic children was 6.3% (19 out of 301 children). The frequency of the (-308)A TNF-alpha variant was similar in the CD and the non-CD groups, exceeding the Hungarian healthy reference value. The number of (-238)A allele carriers was higher in the CD (4/19) than in the non-CD group (17/277) (p < 0.05).

CONCLUSIONS

Our study is limited by the small number of CD patients. On the basis of our findings, carriers of TNF (-308)A allele do not seem to have an increased risk for CD in T1DM. The association between TNF-alpha(-238)A allele carrier state and CD requires further investigation.

Coeliac disease and risk of tuberculosis: a population based cohort study

BACKGROUND

Coeliac disease (CD) is an autoimmune disease often characterised by malnutrition and linked to a number of complications such as an increased risk of lymphoma, adverse pregnancy outcome, and other autoimmune diseases. Tuberculosis (TB) affects a large proportion of the world population and is more common in individuals with malnutrition. We investigated the risk of TB in 14 335 individuals with CD and 69 888 matched reference individuals in a general population based cohort study.

METHODS

Cox proportional hazards method was used to calculate the risk of subsequent TB in individuals with CD. In a separate analysis, the risk of CD in individuals with prior TB was calculated using conditional logistic regression.

RESULTS

CD was associated with an increased risk of subsequent TB (hazard ratio (HR) 3.74, 95% CI 2.14 to 6.53; p < 0.001). Similar risk estimates were seen when the population was stratified for sex and age at CD diagnosis. Individuals with CD were also at increased risk of TB diagnosed in departments of pulmonary medicine, infectious diseases, paediatrics, or thoracic medicine (HR 4.76, 95% CI 2.23 to 10.16; p < 0.001). The odds ratio for CD in individuals with prior TB was 2.50 (95% CI 1.75 to 3.55; p < 0.001).

CONCLUSIONS

CD is associated with TB. This may be due to malabsorption and lack of vitamin D in persons with CD. Individuals with TB and gastrointestinal symptoms should be investigated for CD.

Genetics of inflammatory bowel disease: The role of the HLA complex

The human leucocyte antigen (HLA) complex on chromosome 6p21.3 is the most extensively studied genetic region in Inflammatory bowel disease (IBD). Consistent evidence of linkage to IBD3 (6p21.1-23), an area which encompasses the HLA complex, has been demonstrated for both Crohn’s disease and ulcerative colitis, and a number of replicated associations with disease susceptibility and phenotype have recently emerged. However, despite these efforts the HLA susceptibility gene (s) for IBD remain elusive, a consequence of strong linkage disequilibrium, extensive polymorphism and high gene density across this region. This article reviews current knowledge of the role of HLA complex genes in IBD susceptibility and phenotype, and discusses the factors currently limiting the translation of this knowledge to clinical practice.

Risk of celiac disease in children with type 1 diabetes is modified by positivity for HLA-DQB1*02-DQA1*05 and TNF -308A

OBJECTIVE

The overlap between genetic susceptibility to celiac disease (CD) and to type 1 diabetes is incomplete; therefore, some genetic polymorphisms may significantly modify the risk of CD in subjects with type 1 diabetes. This study aimed to investigate whether the susceptibility to CD in diabetic children is modified by positivity for HLA-DQB1*02-DQA1*05 and DQB1*0302-DQA1*03 and by alleles of single nucleotide polymorphisms within the genes encoding CTLA4, transforming growth factor (TGF)-beta, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1, IL-2, IL-6, and IL-10.

RESEARCH DESIGN AND METHODS

Genotypic data were compared between 130 case subjects (children with type 1 diabetes and CD diagnosed using endomysium antibodies) and 245 control subjects (children with type 1 diabetes only, optimally two per case, matched for center, age at type 1 diabetes onset, and type 1 diabetes duration). The subjects were recruited from 10 major European pediatric diabetes centers performing regular screening for CD. The polymorphisms were determined using PCR with sequence-specific primers, and the risk was assessed by building a step-up conditional logistic regression model using variables that were significantly associated with CD in the univariate analysis.

RESULTS

The best-fitted model showed that risk of CD is increased by presence of HLA-DQB1*02-DQA1*05 (odds ratio 4.5 [95% CI 1.8-11], for homozygosity, and 2.0 [1.1-3.7], for a single dose) and also independently by TNF -308A (1.9 [1.1-3.2], for phenotypic positivity), whereas IL1-alpha -889T showed a weak negative association (0.6 [0.4-0.9]).

CONCLUSIONS

The results indicate that the risk of CD in children with type 1 diabetes is significantly modified both by the presence of HLA-DQB1*02-DQA1*05 and by a variant of another gene within the major histocompatibility complex, the TNF -308A.

Interleukin-10 haplotypes in Celiac Disease in the Spanish population

Background

Celiac disease (CD) is a chronic disorder characterized by a pathological inflammatory response after exposure to gluten in genetically susceptible individuals. The HLA complex accounts for less than half of the genetic component of the disease, and additional genes must be implicated. Interleukin-10 (IL-10) is an important regulator of mucosal immunity, and several reports have described alterations of IL-10 levels in celiac patients. The IL-10 gene is located on chromosome 1, and its promoter carries several single nucleotide polymorphisms (SNPs) and microsatellites which have been associated to production levels. Our aim was to study the role of those polymorphisms in susceptibility to CD in our population.

Methods

A case-control and a familial study were performed. Positions -1082, -819 and -592 of the IL-10 promoter were typed by TaqMan and allele specific PCR. IL10R and IL10G microsatellites were amplified with labelled primers, and they were subsequently run on an automatic sequencer. In this study 446 patients and 573 controls were included, all of them white Spaniards. Extended haplotypes encompassing microsatellites and SNPs were obtained in families and estimated in controls by the Expectation-Maximization algorithm.

Results

No significant associations after Bonferroni correction were observed in the SNPs or any of the microsatellites. Stratification by HLA-DQ2 (DQA1*0501-DQB1*02) status did not alter the results. When extended haplotypes were analyzed, no differences were apparent either.

Conclusion

The IL-10 polymorphisms studied are not associated with celiac disease. Our data suggest that the IL-10 alteration seen in patients may be more consequence than cause of the disease.

IL-10 polymorphisms are associated with early-onset celiac disease and severe mucosal damage in patients of Caucasian origin

PURPOSE

Polymorphisms in cytokine genes can determine their level of expression and affect the phenotypic expression of immunomediated diseases, such as celiac disease (CD). We thus evaluated cytokine polymorphism prevalence in CD patients and population controls, and assessed the correlation between specific polymorphisms and celiacs' clinical characteristics.

METHODS

155 CD patients and 202 population controls were enrolled in the study. Cytokine polymorphisms (TNFalpha -308 and -238, IL-1beta -511 and +3954, IL-1b RN + 2018, IL-6 -174, IL-10 -1082, -819 and -592, TGFbeta1 + 29 and +74, IFN-gamma + 874) and HLA class II alleles were determined by sequence-specific primer polymerase chain reaction or restriction fragment length polymorphism analysis. Duodenal histology was classified using Marsh's criteria. Variables significantly associated with CD patients' characteristics were identified by multivariate logistic regression analysis.

RESULTS

A significantly higher frequency of -308 TNFalpha polymorphism was observed in CD patients compared to the entire population control group, although no difference was detected when population controls were stratified according to HLA class II. Among celiacs, early onset of the disease (< or =2 year old) and the presence of a severe intestinal lesion (Marsh 3C) were significantly associated with the -1082 A/A IL-10 genotype which corresponds to a low producer phenotype (OR 3.28, 95% CI 1.49-7.19 and OR 2.60, 95% CI 1.04-6.49, respectively).

CONCLUSION

The association between IL-10 genotypes and both histological severity at diagnosis and age of onset could be related to an alteration in cytokine balance, and supports the idea that the various clinical manifestations of the disease could be determined by a different genetic background.

Evaluation of cytokine polymorphisms (TNFalpha, IFNgamma and IL-10) in Down patients with coeliac disease

BACKGROUND

In Down syndrome there is an increased prevalence of coeliac disease, but the reasons for this association are yet unknown.

AIMS

To evaluate a possible correlation between TNFalpha, IFNgamma and IL-10 genotype polymorphisms with the susceptibility to coeliac disease in Down syndrome patients.

METHODS

Single nucleotide polymorphisms of TNFalpha (-308G-->A promoter region), IFNgamma (+874T-->A promoter region) and IL-10 (-1082G-->A promoter region) have been studied in 10 Down patients with coeliac disease, in 40 Down patients without coeliac disease and in 220 healthy controls. Clinical features were also studied in coeliac disease-Down syndrome patients.

RESULTS

The 10 coeliac disease-Down syndrome patients had a biopsy proven coeliac disease afterward a serological testing positive to antigliadin, antiendomysium and antitransglutaminase antibodies. Intestinal biopsy showed total atrophy in 6/10 and partial villous atrophy in 4/10 of them. All coeliac disease-Down syndrome patients had silent forms of coeliac disease and classical trisomy 21. No significant differences were observed for the IFNgamma and IL-10 polymorphisms in the studied groups. A significant trend for increase of TNFalpha -308A positive frequency was observed in coeliac disease-Down syndrome patients compared to healthy controls (p=0.043).

CONCLUSIONS

Single nucleotide polymorphisms of IFNgamma and IL-10 do not play a role in predisposing Down syndrome patients to coeliac disease, while the TNFalpha -308 allele could be an additional genetic risk factor for coeliac disease in trisomy 21.

TNFalpha, IFNgamma and IL-10 gene polymorphisms in a sample of Sicilian patients with coeliac disease

BACKGROUND

Coeliac disease is associated with DQ2 and DQ8 alleles, but other genes also confer an additional genetic risk.

AIMS

Defining whether the genetic profiles of interleukin-10, tumour necrosis factor alpha and interferon gamma are associated with an increased coeliac disease risk.

PATIENTS AND METHODS

The functionally gene polymorphisms of tumour necrosis factor alpha (-308G/A), interferon gamma (+874T/A) and interleukin-10 (-1082G/A) were typed using sequence specific primer-polymerase chain reaction in 110 Sicilian coeliac disease patients and in 220 Sicilian healthy controls.

RESULTS

No differences in genotype frequencies of interleukin-10 polymorphisms were found between coeliac disease patients and healthy controls. A significant increase of -308A (p<0.033; OR: 1.72; CI: 1.27-2.33) and of +874T (p: 0.0045; OR: 3.02; CI: 1.47-6.21) allele frequencies, both in hetero- and homozygosis, was observed in coeliac patients in comparison with healthy controls. In addition, simultaneous significant higher percentages of -308A and +874T alleles (p: 0.0066; OR: 2.33; CI: 1.42-3.82) as well as simultaneous significant lower percentages of -308A and +874T alleles (p: 0.003; OR: 0.23; CI: 0.10-0.60) were observed in coeliac patients compared with healthy controls.

CONCLUSIONS

Genetically determined higher frequencies of -308A tumour necrosis factor alpha and +874T interferon gamma alleles, both in hetero and in homozygosis and mostly whether simultaneous, may play a role in predisposing to gluten intolerance. Subjects positive for -308A tumour necrosis factor alpha and +874T interferon gamma alleles have an increased risk for coeliac disease.

IL6, IL10 and TGFB1 gene polymorphisms in coeliac disease: differences between DQ2 positive and negative patients

Predisposition to coeliac disease (CD) might be partially due to an individual pattern of hyper-inflammatory biased immune response. One of these patterns of intense response may be linked to the haplotype carrying HLA-DQ2 alleles and TNF -308A allele. However, 10 % of CD patients do not express the DQ2 heterodimer and these do not usually carry the TNF -308A allele. A similar response might be achieved by genes codifying other cytokines.

OBJECTIVES

To study biallelic polymorphisms in genes codifying for TNFalpha, IL10, IL6 and TGFbeta1 in DQ2 negative CD patients and to compare the results with DQ2 positive patients and healthy controls, in order to establish whether any of these polymorphisms have a role in CD susceptibility.

METHODS

TNF -308 (G > A), IL-6 -174 (G > C) and TGFB1 codon 10 (+ 869, T > C) and codon 25 (+ 915, G > C) polymorphisms and IL-10 haplotype of polymorphisms in positions -1082 (G > A), -819 (C > T) and -592 (C > A) were typed by a SSP-PCR technique.

RESULTS

The distribution of allele frequencies for TNF -308 is different between DQ2 positive CD patients and controls and the same occurs for haplotype frequencies of the IL10 promoter (-1082, -819, -592): The frequencies of the TNF -308A allele (p = 0.027), TNF -308A carriers (p = 0.031) and of IL10GCC haplotype are increased (p = 0.013) in DQ2 positive CD patients. However, the IL6 -174 allele G is more frequent in DQ2 negative patients than in healthy controls (p = 0.018), DQ2 negative controls (p = 0,018), and DQ2 positive patients (p = 0.008).

CONCLUSIONS

DQ2 negative CD patients show an increased frequency of genotypes associated to IL6 high production. These were mainly allele G homozygous for the IL6 gene (-174) polymorphism. The IL6 -174GG genotype (homozygous) may be an additional risk marker for CD in DQ2 negative patients, representing an alternative susceptibility factor for CD when TNF -308A is negative.

Association study of functional genetic variants of innate immunity related genes in celiac disease

Background

Recent evidence suggest that the innate immune system is implicated in the early events of celiac disease (CD) pathogenesis. In this work for the first time we have assessed the relevance of different proinflammatory mediators typically related to innate immunity in CD predisposition.

Methods

We performed a familial study in which 105 celiac families characterized by the presence of an affected child with CD were genotyped for functional polymorphisms located at regulatory regions of IL-1α, IL-1β, IL-1RN, IL-18, RANTES and MCP-1 genes. Familial data was analysed with a transmission disequilibrium test (TDT) that revealed no statistically significant differences in the transmission pattern of the different genetic markers considered.

Results

The TDT analysis for IL-1α, IL-1β, IL-1RN, IL-18, and MCP-1 genes genetic variants did not reveal biased transmission to the affected offspring. Only a borderline association of RANTES promoter genetic variants with CD predisposition was observed.

Conclusion

Our results suggest that the analysed polymorphisms of IL-1α, IL-1β, IL-1RN, IL-18, RANTES and MCP-1 genes do not seem to play a major role in CD genetic predisposition in our population.

Genetic testing: who should do the testing and what is the role of genetic testing in the setting of celiac disease?

Celiac disease is a remarkable and common immune-mediated disorder determined by both the presence of characteristic HLA alleles (DQ2 and DQ8) and one of the best characterized environmental factors (gliadin) for any common autoimmune disease. The discovery of transglutaminase autoantibodies and the development of assays for these antibodies has allowed the identification of a large number of asymptomatic individuals with autoimmunity and intestinal biopsy evidence of celiac lesions. Further understanding of the sequelae of asymptomatic celiac disease, and the interaction between genetic susceptibility and environmental factors, are likely to alter fundamentally both genetic screening for celiac disease and its therapy.

Cytokine Gene Polymorphisms and Genetic Association with Coeliac Disease in the Finnish Population

Coeliac disease (CD) is an intestinal disorder caused by intolerance to dietary gluten in susceptible individuals. The HLA-DQ genes are major risk factors for CD, but other genes also play an important role in the disease susceptibility. Immune-mediated mechanisms are known to underlie the pathogenesis of CD. We studied single-nucleotide polymorphisms in transforming growth factor (TGF)-beta1, interleukin (IL)-10, IL-6, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha genes in the Finnish population using family-based association approach. In addition, we genotyped a trinucleotide repeat polymorphism in the major histocompatibility complex (MHC) class I chain-related protein A (MICA) gene, located in the human leucocyte antigen (HLA) region in the vicinity of TNF-alpha. To control the effect of linkage disequilibrium between HLA-DQ genes and MICA and TNF-alpha, an HLA-stratified association analysis was performed. We did not find evidence of association between TGF-beta1, IL-10, IL-6 and IFN-gamma polymorphisms and CD susceptibility. No association was found for any of the MICA alleles independently of DQ genes, whereas TNF-alpha-308 A allele was slightly overrepresented on chromosomes carried by CD patients compared with control chromosomes, indicating that either TNF-alpha, or another gene in linkage disequilibrium with it, could confer increased susceptibility to CD. This result supports the earlier findings that the HLA region harbours a novel susceptibility factor in addition to HLA-DQ.

[Genetics and immunopathogenics aspects of the celiac disease: a recent vision]

BACKGROUND

Celiac disease, or gluten-sensitive enteropathy, is a strongly inherited condition. Although the genetic association of CD with the DQ2 and DQ8 HLA haplotypes has been known for long, others HLA and non-HLA genes are also important in the development of the disease. Celiac disease results of the combined effect of different normally functioning genes' products. The tissue damage in celiac disease is immunologically mediated and several effector mechanisms are responsible for the disease expression. The interplay between genetic, immunological and environmental factors explains the large spectrum of clinical, histological and serological alterations observed in the different stages of the disease development, pointing out to the polygenic nature of celiac disease.

CONCLUSION

The recent advances in the understanding of the immunopathogenesis, genetics and diagnoses of celiac disease have allowed the revision of strict concepts and previous criteria and their adequation to the new evidences, aiming a better diagnostic and orientation to celiac patients and relatives.

Haplotype variation at the IBD5/SLC22A4 locus (5q31) in coeliac disease in the Irish population

In addition to the well-established association of coeliac disease (CD) with HLA-DQ (6p21) and possibly CTLA4 (2q33), there is considerable evidence for a susceptibility locus on chromosome 5q, which contains many potential candidates for inflammatory disease, including a cluster of cytokine genes in 5q31. CD cases and controls were genotyped for four single-nucleotide polymorphism (SNP) markers that together characterize >90% of the haplotype variation at the IBD5 locus encoding, among others, the SLC22A4 gene. IBD5 and SLC22A4 map to 5q31 and have recently been associated with Crohn's disease and rheumatoid arthritis. Haplotype frequencies do not differ significantly between CD cases and controls in the Irish population, and therefore the chromosome 5 CD susceptibility locus most likely lies elsewhere on 5q.

Defining the contribution of the HLA region to cis DQ2-positive coeliac disease patients

The major genetic susceptibility to coeliac disease is contributed by the human leukocyte antigen (HLA) region. The primary association is with the HLA-DQ2 molecule, encoded by the DQA1*05 and DQB1*02 alleles, which is expressed by over 90% of patients. The aim of our study was to perform an extensive scan of the entire HLA region to determine whether there is evidence for the presence of additional HLA susceptibility genes for coeliac disease in the Dutch population, acting independently of DQ2. In all, 16 microsatellite markers and the DQA1 and DQB1 genes were genotyped in simplex cis DQ2-positive coeliac disease families and cis DQ2-positive control families. Allele frequencies of markers on phase-known DQ2-positive haplotypes transmitted to patients were compared to a combined group of DQ2-positive nontransmitted and control haplotypes, thereby controlling for the DQ2 contribution. No significant differences at any of the marker loci were detected, suggesting that DQ2 is the major HLA risk factor for coeliac disease. Individuals homozygous for DQ2 or heterozygous for DQA1*05-DQB1*02/DQA1*0201-DQB1*02 were found to be at five-fold increased risk for development of coeliac disease (P<10(-8)). This risk seems to be conferred by the presence of a second DQB1*02 allele next to one DQA1*05-DQB1*02 haplotype, independently of the second DQA1 allele.

Analysis of tumour necrosis factor alpha and interleukin 10 promotor variants in patients with chronic pancreatitis

OBJECTIVE

Cationic trypsinogen gene mutations are strong risk factors of hereditary pancreatitis. However, 20% of subjects with a trypsinogen mutation never get pancreatitis and the cause of this incomplete penetrance is unknown. We investigated the influence of interleukin 10 (IL10) and tumour necrosis factor alpha (TNFalpha) promotor variants on the manifestation of chronic pancreatitis of different underlying causes and in pancreatic cancer.

METHODS

A total of 335 German patients with chronic pancreatitis were investigated. In 157 patients the disease was related to alcohol abuse; the other cases were of non-alcoholic origin. In the latter group, the serine protease inhibitor, Kazal type 1 (SPINK1) mutation N34S was found in 72 patients and the trypsinogen mutations N29I or R122H were present in 60 patients; in the remaining 46 patients no mutation was found. In addition, we studied 208 patients with pancreatic cancer. As controls, 116 healthy blood donors and 25 healthy carriers of the trypsinogen mutations N29I or R122H were investigated. After DNA extraction from blood leucocytes, genotyping for the cytokine polymorphisms was performed by induced heteroduplex generators and/or direct DNA sequencing of the IL10 and TNFalpha promotor regions.

RESULTS

The frequencies of the promotor polymorphisms of IL10-627A, IL10-1117A, TNF-238A and TNF-308A in patients with alcoholic chronic pancreatitis, idiopathic pancreatitis, SPINK1-N34S-associated chronic pancreatitis and pancreatic cancer did not differ significantly from the control group. The variant TNF-238A was two to four times more frequent in index patients with trypsinogen mutations than in all other groups. The analysis of the allelic frequencies of whole families with trypsinogen mutations revealed that all subjects with the TNF-238A variant suffered from chronic pancreatitis, whereas all intrafamilial controls with wild-type TNF were unaffected.

CONCLUSIONS

TNFalpha and IL10 promotor variants are not associated with a manifestation of chronic pancreatitis or pancreatic cancer. The variant TNF-238A, however, might be a relevant risk factor for disease manifestation in families with hereditary pancreatitis.

The TNF2 allele is a risk factor to severe aplastic anemia independent of HLA-DR

Severe aplastic anemia (SAA) is a disease with an autoimmune component. The susceptibility to the development of SAA is strongly associated with genes in the major histocompatibility complex (MHC). The gene for tumor necrosis factor-alpha (TNF-alpha) is encoded in the MHC locus and TNF-alpha is involved in the pathogenesis of SAA. A TNF-alpha variant with a polymorphism at position -308 in its promoter region (-308A), which is designated TNF2, has been demonstrated to be linked to a number of autoimmune diseases. In this study, the TNF-alpha -308 promoter polymorphism and HLA-DRB1 alleles were analyzed in 75 SAA patients, 55 mild aplastic anemia patients (MAA), and 128 controls. In SAA the phenotype frequencies of TNF2, HLA-DR3, and -DR2 were significantly higher in comparison to controls. Stratification analysis confirmed that the TNF2 allele contributes to the susceptibility to SAA independently of HLA-DR3 or -DR2. The results indicated that TNF2 might act as an independent risk factor for SAA.

Plasma cytokine profiles in patients with celiac disease and selective IgA deficiency

Celiac disease (CD) and selective IgA deficiency (IgAD) are frequently associated, and share the same genetic background. The aim of the present study was to evaluate both Type 1 and 2 plasma cytokine levels in CD and in CD-IgAD. IL-2, TNF-alpha, IL-10, IL-4 and IL-13 plasma levels were measured both at diagnosis and after a gluten-free diet (GFD) in 32 CD patients, in 27 CD-IgAD patients and in 30 healthy controls. IFN-gamma levels were significantly higher in CD and CD-IgAD than in controls, TNF-alpha displayed significantly higher levels in CD-IgAD when compared both with controls and with CD, and IL-2 was in CD-IgAD significantly increased respect to controls. Kinetics of the Type 1 cytokine plasma levels did not show a clear relationship with the GFD in both groups of CD patients, and particularly in those with IgAD. IL-4 and IL-13, both at diagnosis and after a GFD, were not significantly different in controls and in celiac patients (with and without IgAD). IL-10, whose production is stimulated by the TNF-alpha, had significantly higher plasma levels in CD-IgAD, but not in CD patients, with a significant decrease after a GFD. CD and especially CD-IgAD patients display persistently higher pro-inflammatory cytokine levels, suggesting a persistent state of activation of pro-phlogistic signals in CD, particularly when IgAD coexists. Serial measurement of serum IL-10 may be an adjunctive evaluating criterion in the follow-up of CD-IgAD patients.

Coeliac disease patients carry conserved HLA-DR3-DQ2 haplotypes revealed by association of TNF alleles

Certain HLA-DQ alleles are known to contribute to predisposition to coeliac disease (CD). The existence of additional independent risk-modifying loci in the HLA complex is still being debated. The DR3-DQ2 haplotype has been studied most, but the evidence is conflicting. The discrepancies may stem from the absence of such an effect, insufficient statistical power to detect an effect (i.e. small studies) and/or incomplete control of linkage disequilibrium (LD) to the neighbouring DQ-loci, known to elicit a strong effect. In the present study, we aimed to undertake a statistically high-powered family-based analysis, fully controlling effects of LD between the major DQ-risk haplotypes and neighbouring candidate loci. We investigated five markers on DR3-DQ2, DR5-DQ7 and DR7-DQ2 haplotypes in 327 Norwegian and Swedish families. Our primary finding was that TNF-308A ( TNF2) was significantly associated on the DR3-DQ2 haplotype [stratum specific odds ratio (OR) = 2.40 (1.25-4.48), Pc = 0.009, where P(c) = Pn and n = number of tests performed]. Furthermore, we confirmed earlier indications that LD between TNF2 and DQA1*05-DQB1*02 on the DR3 haplotype is more strongly maintained in family-based cases than family-based controls. In conclusion, we confirmed in this study, the largest of its kind, that additional CD risk factors independent of DQ2 alleles do exist on the DR3 haplotype.

Association of -1087 IL10 and -308 TNFA gene polymorphisms with serological markers of coeliac disease

Coeliac disease (CD) is known to have a strong genetic background. We analyzed the association between serological markers of CD and the -1087 IL10 and -308 TNFA gene polymorphisms in Swedish patients. A higher frequency of the TNF2 allele was present in the patients compared with the controls (p < 0.0001). The frequency of the AA genotype of the IL10 gene in the patients was unexpectedly higher in comparison with the controls (p < 0.05). The levels of IgA anti-endomysium and antitissue transglutaminase antibodies were associated with IL10 but not with TNFA genotype. The patients with the AA or GG -1087 IL10 genotypes had significantly lower levels of antibodies in comparison with those with the AG genotype (p < 0.05 to p < 0.0005). However, when divided according to potential level of IL-10 production, the group of potentially high IL-10 producers among the CD patients demonstrated significantly lower levels of antitissue transglutaminase antibodies compared to potentially low IL-10 producers (p = 0.01). Our results show a relationship between the levels of IgA antibodies involved in CD with the IL10 genotypes. This suggests a possible involvement of IL-10 in the development of the disease.

Additional factor in some HLA DR3/DQ2 haplotypes confers a fourfold increased genetic risk of celiac disease

Although HLA-DQ genes are the major celiac disease (CD) susceptibility genes, results from Finnish families suggest that not all DQ2-encoding haplotypes confer equal susceptibility to CD, implying the effect of other gene(s) in the HLA region. The aim of the present work was to extend and confirm the aforementioned results in a southern European population ( Italian) and to better localize the additional risk factor/s. The association of nine loci spanning the HLA region from DR to HFE, 4.5-Mb telomeric of HLA-A, was tested. The analysis was performed by comparing marker frequencies in DR3-DQ2 haplotypes transmitted and non-transmitted to the affected offspring in 156 Italian CD families selected for having at least one DR3-positive parent. The same analysis was performed independently in 101 Finnish CD families selected with the same criteria. Three alleles, MICA-A5.1, MICB-CA24 and MIB-350, all characteristic of the B8-DR3 extended haplotype, showed a significantly increased frequency in DR3 transmitted haplotypes in the Italian families. DR3 haplotypes carrying the combination of these alleles conferred an approximate fourfold increased CD risk. B8-DR3 transmitted haplotypes were significantly more conserved telomerically down to the MIC-Class I region. Similar results were seen in the Finnish families. The major conclusion that holds true in both populations is that, while DQ2 is an absolute requirement for the development of CD, the presence of an additional genetic factor within the MIC-Class I region confers an approximate 4-fold increased risk of the disease.

Cytokine genotyping (TNF and IL-10) in patients with celiac disease and selective IgA deficiency

OBJECTIVE

Selective IgA deficiency (IgAD) and celiac disease (CD) are frequently associated and share the ancestral haplotype human leukocyte antigen (HLA)-8.1, which is characterized by a peculiar cytokine profile. The aim of this study was to evaluate the role of tumor necrosis factor (TNF) and interleukin (IL)-10 alleles in CD and CD-IgAD.

METHODS

The distribution of some biallelic polymorphisms of both cytokine promoters (-308G-->A and -863C-->A at TNF promoter sequence and -1082G-->A, -819C-->A, and -592C-->T at IL-10 promoter) were typed using biotilinated specific probes in 32 celiac patients, in 34 CD-IgAD patients, and in 96 healthy controls.

RESULTS

In CD and CD-IgAD, the -308A allele was significantly more frequent than in controls, whereas no significant differences were observed for the biallelic polymorphisms at the -863 and for the three IL-10 promoter polymorphisms. The evaluation of combined TNF and IL-10 genotypes showed in CD-IgAD a significant reduction of -308G/-1082G homozygous subjects and both in CD and CD-IgAD groups an increase of 308AA/1082GG. Accordingly, CD-IgAD patients positive both for -308A TNF and -1082A IL-10 showed an increase of TNF-alpha and a reduction of IL-10 serum levels.

CONCLUSIONS

Genetically determined increased production of TNF-alpha and reduction of IL-10 may be relevant for susceptibility to CD, mainly in IgAD, as the different allele expression at TNF and IL-10 loci seems to influence cytokine production profile.

Atopic asthma and TNF-308 alleles: linkage disequilibrium and association analyses

The association of a tumor necrosis factor -308 allele (TNF2) to asthma has been reported in some studies but not in others. The aim of this study was to test this association in a population recruited on the basis of allergy to Parietaria. In the study population, asthma was positively associated to HLA-DRB1*03 (p = 0.01) and to the haplotype TNF2/DRB1*03 (p = 0.02). In the parent subgroup, the proportion of asthmatics was increased in patients with TNF2 (p = 0.01), but the primary association of asthma was to the haplotype TNF2/DRB1*1104 (p = 0.005). The study population was subdivided according to prick skin test (ST) positivity to Lolium, Parietaria, and D. pteronyssinus. Asthma was associated to HLA-DRB1*03 and to the haplotype TNF2/DRB1*03 (p = 0.0015 and 0.0001, respectively) in patients ST positive to Lolium, and to the haplotype TNF2/DRB1*1104 (p = 0.025) in patients ST positive to Parietaria. The transmission disequilibrium test detected excess transmission of HLA-DRB1*03 and of the haplotype TNF2/DRB1*03 (p = 0.03 and 0.04, respectively) to siblings with asthma and ST positivity to Lolium and of HLA-DRB1*1104 and of the haplotype TNF2/DRB1*1104 (p = 0.04 and 0.015, respectively) to siblings with asthma and ST positivity to Parietaria. Taken together, these observations indicate that the haplotypes TNF2/DRB1*03 and TNF2/*B1*1104 contain alleles controlling atopic asthma in patients with sensitization to Lolium and Parietaria, respectively. This suggests that the association of asthma to TNF2 reflects linkage disequilibrium with genes influencing specific immune response.

A collaborative European search for non-DQA1*05-DQB1*02 celiac disease loci on HLA-DR3 haplotypes: analysis of transmission from homozygous parents

The HLA-DQA1*05 with DQB1*02 alleles are a major risk factor for celiac disease (CD). To search for additional human leukocyte antigen (HLA) risk factors, we looked on the DR3-DQ2 risk haplotype, selected because it carries both DQ risk alleles in cis and is the more represented among CD patients. In a European consortium, we identified 109 families with a parent homozygous for DQA1*05-DQB1*02. We typed ten microsatellites in the extended HLA complex, and applied the homozygous-parent transmission disequilibrium test (HPTDT) and extended-TDT to transmissions from homozygous parents. These methods eliminate confounding due to linkage disequilibrium between candidate disease loci and the known risk factor DQA1*05-DQB1*02, and are favorable when sufficient families are available. We did not find evidence of association with any single marker or allele, although weak evidence for additional risk was observed, represented by preferential transmission of six adjacent markers. We tested the largest ever reported HPTDT population in CD, providing unprecedented power. We did not find significant evidence of additional risk-modifying factors on the DR3 haplotype, independent of DQA1*05-DQB1*02, although a weak tendency was observed for the B8-DR3 haplotype. This effect should be tested in large populations with significant representations of both B8-DR3 and non-B8 DR3 haplotypes.

HLA in coeliac disease: unravelling the complex genetics of a complex disorder

Coeliac disease (gluten sensitive enteropathy) is a common, polygenic and multifactorial disorder that serves as a pioneering model for the study of inflammatory disease. A major environmental factor is known (ingested gluten from wheat), and there is unprecedented genetic and functional evidence pinpointing HLA-DQA1*05-DQB1*02 ( DQ2) and DQA1*03-DQB1*0302 ( DQ8) in disease predisposition. We discuss the current state of play in coeliac disease genetics, focussing particularly on the HLA complex. Emerging evidence suggests that additional HLA risk loci exert weak effects, independent of DQA1*05-DQB1*02, on the B8-DR3-DQ2 haplotype. There is also good evidence from linkage studies of disease gene(s) on chromosome 5q. We discuss the role and implications of linkage disequilibrium and haplotype blocks in complex disease gene mapping. We briefly address findings from studies of animal models for chronic inflammatory disease, and consider roles for both common genes associated with multiple inflammatory diseases, and genes unique to coeliac disease. The coeliac genetics research community has established a sound foundation for the identification of additional disease genes in the not-too-distant future. Functional studies will play a critical role, and coeliac disease has a promising future in this respect. Coeliac disease continues to function as a model disorder, facilitating the development and implementation of complex disease gene mapping strategies.

Pediatric celiac disease in India is associated with multiple DR3-DQ2 haplotypes

The role of human leukocyte antigen (HLA) DQ2 heterodimer (DQA1*0501-DQB1*0201) in presenting gluten peptides to effector T cells in celiac disease (CD) has been well documented. Because HLA-DQ2 is carried on DR3 haplotypes due to linkage disequilibrium, such haplotypes are encountered more frequently in patients with autoimmune disease. This study analyzed 35 North Indian children below 15 years of age and diagnosed to have CD as per the ESPGAN criteria, which included histopathologic alterations in duodenal biopsies, clinical response to gluten withdrawal, and presence of antiendomysial antibodies. The HLA class I and class II alleles were determined by polymerase chain reaction-sequence-specific primers, sequence-specific oligonucleotide probe, and reverse line strip molecular techniques. A statistically significant positive association of the disease with HLA-DRB1*03 (94.2% versus 22.1% in controls, chi(2) = 73.4, p = 7.54E-11), and a negative association with DRB1*15 (chi(2) = 7.4, p = 6.5E-03) and DRB1*13 alleles was observed. The HLA-DQB1*0201 was observed in all the 35 patients (100%), whereas the DQ2 heterodimer alpha(0)beta(0) occurred in 97.1% of CD patients (31.4% in double dose, 65.7% in single dose) and revealed significant deviation from healthy controls (chi(2) = 102.08, p = 7.56E-11). Further analysis revealed involvement of multiple DR3+ve haplotypes with CD in Indians, of which A26-B8-DR3 was the most common DR3 haplotype among patients (34.28%, chi(2) = 40.57, p = 2.65E-10) followed by Ax-B21-DR3 (11.4%) (chi(2) = 13.8, p = 2E-04) and the classical Caucasian haplotype A1-B8-DR3 (5.7%). The former two haplotypes are characteristic of Asian Indians and are involved in the development of CD. We conclude that the high risk DR3 haplotypes that play a crucial role in the development of CD are unique in Asian Indians. Detailed analysis of these haplotypes in Indian patients with autoimmune diseases may help understand the influence of other intervening genes within the major histocompatibility complex.

Tumor necrosis factor gene polymorphism in migraine

OBJECTIVE

To better define the involvement of human leukocyte antigen region (HLA) genes in migraine via an association study of the tumor necrosis factor (TNF) genes, located in the HLA class III region, with migraine with and without aura.

BACKGROUND

Migraine without aura and migraine with aura are disorders involving multiple factors-environmental and genetic. In a previous study, we hypothesized a protective role for the HLA-DR2 antigen, providing additional basis for the proposed genetic heterogeneity between migraine without aura and migraine with aura. The cytokines produced by TNF genes are polypeptide effectors of inflammatory reaction and endothelial function.

METHODS

Tumor necrosis factor (TNF)-308 (TNF-308A and TNF-308G alleles) and lymphotoxin alpha (TNFB*1 and TNFB*2 alleles) polymorphisms were analyzed by the NcoI-cleaved polymerase chain reaction-amplified fragments in 47 patients with migraine without aura, 32 patients with migraine with aura, and 101 migraine-free controls.

RESULTS

The frequency of TNFB*2 allele was significantly increased in our patients with migraine without aura as compared with the control group (78.72% versus 61.4%, Pc =.004), but no significant differences were found between patients with migraine with aura and controls. Additionally, there was a significant decrease of TNFB*1 homozygotes in patients with migraine without aura compared with the control group (2.13% versus 16.8%, Pc =.0201). Carriage of the TNFB*2 allele confers a high risk for the development of migraine without aura. No significant association was found at TNF-308 polymorphism.

CONCLUSION

These data support the hypothesis that lymphotoxin alpha could be a susceptibility gene in migraine without aura and confirm previous data indicating that migraine with and without aura are distinct entities with different genetic backgrounds.

Triplet repeat polymorphism in the transmembrane region of the MICA gene in celiac disease

Celiac disease (CD) is characterized by a striking expansion of gamma delta T cells in the intestine. These cells interact with MICA, a cell surface protein encoded by a major histocompatibility complex gene. We investigated whether MICA gene polymorphism could contribute to susceptibility to CD. DNA typing for HLA-DR, DQA1, DQB1, TNF-308, TNFa, TNFb and a triplet repeat polymorphism in the transmembrane region of the MICA gene were carried out. We performed case-control stratified association studies and transmission disequilibrium tests. Our results indicate that although there is no primary association between MICA polymorphism and CD, there is, in addition to HLA-DQ, a second susceptibility locus on the 8.1 ancestral haplotype in strong linkage disequilibrium with MICA A5.1 allele.

Localization of central MHC genes influencing type I diabetes

The contribution of MHC class II haplotypes to susceptibility to type I diabetes has been clearly established, and interest has now focused on the effects of additional genes in the MHC region. We have investigated the central MHC alleles on 8.1 ancestral haplotype (HLA-A1, B8, DR3, DQ2), as it is well conserved in Caucasian populations. The HLA-DR3-DQ2 genotype is a recognized risk factor for type I diabetes. Single nucleotide polymorphisms and microsatellites in the MHC were used to map segments of the 8.1 ancestral haplotype carried by type I diabetic and control subjects expressing either HLA-B8 or DR3, but not both these markers. In this way we controlled for the diabetogenic effect of carriage of DR3. Alleles of the 8.1 ancestral haplotype between TNFA-308/D6STNFa and HLA-B were carried with significantly greater frequency in B8(-), DR3(+) type I diabetic patients compared with B8(-), DR3(+) controls. This interval was marked by a BAT1 gene polymorphism and a MIB microsatellite allele.

TNF and LTA gene polymorphisms reveal different risk in gastric and duodenal ulcer patients

A small proportion of patients infected with Helicobacter pylori or using non-steroidal anti-inflammatory drugs (NSAIDs) develops peptic ulcer disease. Since family studies have shown the importance of the genetic background of the host in the development of gastric and duodenal ulcers, immunogenetic factors involved in the regulation of inflammation deserve further study. Polymorphisms in the genes encoding tumour necrosis factor (TNF) and lymphotoxin-alpha (LTA) have been shown to contribute to the severity of infectious disease. Our aim was to study four bi-allelic polymorphisms in the TNF and LTA genes, which occur as five haplotypes, in patients with peptic ulcer disease. A total of 130 patients with duodenal ulcer, 50 with gastric ulcer and 102 ethnically-matched Spanish Caucasian healthy controls were studied. H. pylori infection was determined by invasive and non-invasive tests. Odds ratios were obtained by logistic regression analysis. H. pylori was detected in 91.8% of peptic ulcer patients and in 73.3% of controls (P < 0.001). Patients with gastric ulcer had a lower frequency of the TNF-308 allele 2 and a higher frequency of the LTANcoI 2.2 genotype when compared with duodenal ulcer patients (P < 0.01 and P = 0.03, respectively). Carriers of haplotype TNF-I were more frequent in gastric ulcer patients (49%) than in controls (28%) (P < 0.05) and the haplotype TNF-E was significantly more frequent in duodenal ulcers than in gastric ulcers (27% vs 8.2%; P < 0.01). Logistic regression analysis identified haplotype TNF-I carrier status as an independent risk factor for peptic ulceration in H. pylori-infected patients (OR: 4.2; 95%CI: 1.7-10.2). These results suggest that TNF and LTA gene polymorphisms are related to the development of gastric and duodenal ulcer and may determine disease outcome in H. pylori infection.

Genetic factors underlying gluten-sensitive enteropathy

Genetic epidemiology clearly has shown that there is a genetic predisposition to gluten-sensitive enteropathy (GSE), or celiac disease. The strong genetic component, as determined by the lambda sib (lambda s), has been calculated to lie in the range of 7.5 to 30, based on a 5% to 10% recurrence risk for siblings. Ninety-five percent of northern European patients with GSE carry a particular HLA-DQ alpha beta heterodimer. Studies support the concept that the HLA-DQ gene acts as a dominant gene, and they also found that, in addition to HLA-DQ, a second locus within the major histocompatibility complex (MHC) is involved in the predisposition to GSE in the Dutch population. Genome scans conducted so far suggest that MHC and non-MHC loci collectively contribute to disease susceptibility. Since one, and probably even two, gene(s) from the MHC region itself determine at least 40% to 50% of the genetic predisposition to GSE, it is expected that the other loci each contribute only a little to the total genetic variation. The exact role of these additional genes (i.e., whether they are involved in the initiation or the progression of the disease) remains to be determined.