HLA DQ and DP in Finnish families with celiac disease

Hyperglycemia in Turner syndrome: Impact, mechanisms, and areas for future research

Turner syndrome (TS) is a common chromosomal disorder resulting from complete or partial absence of the second sex chromosome. Hyperglycemia, ranging from impaired glucose tolerance (IGT) to diabetes mellitus (DM), is common in TS. DM in individuals with TS is associated with an 11-fold excess in mortality. The reasons for the high prevalence of hyperglycemia in TS are not well understood even though this aspect of TS was initially reported almost 60 years ago. Karyotype, as a proxy for X chromosome (Xchr) gene dosage, has been associated with DM risk in TS - however, no specific Xchr genes or loci have been implicated in the TS hyperglycemia phenotype. The molecular genetic study of TS-related phenotypes is hampered by inability to design analyses based on familial segregation, as TS is a non-heritable genetic disorder. Mechanistic studies are confounded by a lack of adequate TS animal models, small and heterogenous study populations, and the use of medications that alter carbohydrate metabolism in the management of TS. This review summarizes and assesses existing data related to the physiological and genetic mechanisms hypothesized to underlie hyperglycemia in TS, concluding that insulin deficiency is an early defect intrinsic to TS that results in hyperglycemia. Diagnostic criteria and therapeutic options for treatment of hyperglycemia in TS are presented, while emphasizing the pitfalls and complexities of studying glucose metabolism and diagnosing hyperglycemia in the TS population.

Single cell transcriptomic analysis of the immune cell compartment in the human small intestine and in Celiac disease

Celiac disease is an autoimmune disorder in which ingestion of dietary gluten triggers an immune reaction in the small intestine leading to destruction of the lining epithelium. Current treatment focusses on lifelong adherence to a gluten-free diet. Gluten-specific CD4⁺ T cells and cytotoxic intraepithelial CD8⁺ T cells have been proposed to be central in disease pathogenesis. Here we use unbiased single-cell RNA-sequencing and explore the heterogeneity of CD45⁺ immune cells in the human small intestine. We show altered myeloid cell transcriptomes present in active celiac lesions. CD4⁺ and CD8⁺ T cells transcriptomes show extensive changes and we define a natural intraepithelial lymphocyte population that is reduced in celiac disease. We show that the immune landscape in Celiac patients on a gluten-free diet is only partially restored compared to control samples. Altogether, we provide a single cell transcriptomic resource that can inform the immune landscape of the small intestine during Celiac disease.

Celiac disease is linked to responsiveness to dietary gluten, which manifests itself as immune cell activation and the immunopathology including destruction of the epithelium of the small intestine. Here the authors apply single cell transcriptomics to characterise the immune cell compartment of the human small intestine during active Celiac disease.

An updated overview on celiac disease: from immuno-pathogenesis and immuno-genetics to therapeutic implications

INTRODUCTION

Celiac disease (CD) is an autoimmune enteropathy triggered by ingestion of gluten. While presenting many similarities with other autoimmune diseases, celiac disease is unique in that the external trigger, gluten, and the genetic background necessary for disease development (HLA DQ2/DQ8) are well described. The prevalence of celiac disease is dramatically increasing over the years and new epidemiologic data show changes regarding age of onset and symptoms. A better understanding of CD-pathogenesis is fundamental to highlight the reasons of this rise of celiac diagnoses.

AREAS COVERED

In this review we describe CD-pathogenesis by dissecting all the components necessary to lose tolerance to gluten (ingestion of gluten, genetic predisposition, loss of barrier function and immune response). Additionally, we also highlight the role that microbiome plays in celiac disease as well as new proposed therapies and experimental tools.

EXPERT OPINION

Prevalence of autoimmune diseases is increasing around the world. As a result, modern society is strongly impacted by a social and economic burden. Given the unique characteristics of celiac disease, a better understanding of its pathogenesis and the factors that contribute to it may shed light on other autoimmune diseases for which external trigger and genetic background are not known.

Carrier frequency of HLA-DQB1*02 allele in patients affected with celiac disease: A systematic review assessing the potential rationale of a targeted allelic genotyping as a first-line screening

BACKGROUND

Celiac Disease (CD) is an immune-mediated disorder, in which the HLA immunogenetic background (DQ2 and DQ8 heterodimers) and environmental trigger (gluten) are well established. Indeed, both factors are necessary - but not sufficient - to develop CD. However, it is very likely that CD is underdiagnosed in both developing and developed countries, due to several aspects, including the fact that a lot of patients present mild and/or atypical symptoms, without the presence of any recognized risk factors. Therefore, the possibility and feasibility of widened screening strategies to identify CD patients are debated.

AIM

To provide further evidence of the main epidemiological importance of HLA-DQB1*02 allele in the population of CD patients.

METHODS

We performed a systematic search in PubMed, EMBASE, Cochrane, Web of Science and Scopus databases, in order to produce a systematic review assessing the carrier frequency of HLA-DQB1*02 allele in the celiac population. Following the PRISMA guidelines, we retrieved all the original articles describing CD patients' HLA-DQB1 genotype in such a way that could allow to assess the HLA-DQB1*02 carrier frequency among CD patients, along with the evidence of the appropriate diagnostic work-up to achieve a correct and final diagnosis of CD.

RESULTS

The final output of this systematic search in the medical literature consisted of 38 studies providing the appropriate HLA-DQB1 genotype information of the respective CD population. According to this systematic review, including a pool of 4945 HLA-DQ genotyped CD patients, the HLA-DQB1*02 carrier frequency was 94.94%, meaning that only 5.06% of CD patients were completely lacking this allelic variant. Interestingly, if we consider only the studies whereby the prevalence of CD patients affected with type 1 diabetes mellitus was supposed or clearly established to be very low, the frequency of non-HLA-DQB1*02 carriers among CD patients dropped to 3.65%.

CONCLUSION

Such a high carrier frequency of the HLA-DQB1*02 allelic variant (which is > 95%-96% in CD patients without risk factors, like type 1 diabetes mellitus comorbidity) might be exploited to consider a cost-effective and widened screening approach. If a sustainable strategy could be implemented through a low-cost targeted genetic test to detect the individual presence of HLA-DQB1*02 allele, an appropriate algorithm for serological screening in individuals resulting to be genetically predisposed to CD, might be considered.

Classical celiac disease is more frequent with a double dose of HLA-DQB1*02: A systematic review with meta-analysis

BACKGROUND AND AIMS

Experimental data suggest that the HLA-DQ2 gene dose has a strong quantitative effect on clinical outcomes and severity of celiac disease (CD). We aimed to conduct a meta-analysis with systematic review to investigate the association between HLA-DQB1*02 gene doses and the characteristics of CD.

METHODS

We searched seven medical databases for studies discussing HLA-DQB1 gene dose in CD and various disease characteristics, such as clinical presentation, histology, age at diagnosis, and comorbidities. Odds ratios (OR, for categorical variables) and weighted mean differences (for age) were calculated to compare patients with a double dose of HLA-DQB1*02 versus those with single and zero doses. Heterogeneity was tested with I2-statistics and explored by study subgroups (children and adults).

RESULTS

Twenty-four publications were eligible for meta-analysis. Classical CD was more frequent with a double versus single dose of the HLA-DQB1*02 allele (OR = 1.758, 95%CI: 1.148-2.692, I2 = 0.0%). In pediatric studies, gene dose effect was more prominent (OR = 2.082, 95%CI: 1.189-3.646, I2 = 0.0% and OR = 3.139, 95%CI: 1.142-8.630, I2 = 0.0% for the comparisons of double versus single and double versus zero dose, respectively). Atrophic histology was more prevalent with a double versus zero dose (OR = 2.626, CI: 1.060-6.505, I2 = 21.3%). We observed no gene dose effect regarding diarrhea, age at diagnosis, the severity of villous atrophy, and the association with type 1 diabetes mellitus.

CONCLUSION

A double dose of HLA-DQB1*02 gene seems to predispose patients to developing classical CD and villous atrophy. Risk stratification by HLA-DQB1*02 gene dose requires further clarification due to the limited available evidence.

Risk of Celiac Disease in the First- and Second-Degree Relatives of Patients With Celiac Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

First-degree relatives (FDRs) of patients with celiac disease (CD) are at high risk for CD and prevalence among them varies from 1.6 to 38%. The risk of having CD among FDRs if the FDR is sister, brother, mother, father, son, or daughter of index patient with CD is not known. We conducted a meta-analysis and calculated pooled prevalence of CD among FDRs, second-degree relatives (SDRs), and specific relations with index patient.

METHODS

On search of literature, 2,259 articles appeared of which 54 articles were included in this meta-analysis. Diagnosis of CD was based on standard criteria.

RESULTS

Pooled prevalence of CD was 7.5% (95% confidence interval (CI) 6.3%, 8.8%) in 10,252 FDRs and 2.3% (95% CI 1.3%, 3.8%) in 642 SDRs. Pooled prevalence of CD was highest in siblings (8.9%), followed by offsprings (7.9%) and parents (3.0%). Female FDRs had higher prevalence than male FDRs (8.4% vs. 5.2%, P=0.047). While sisters and daughters of index patient had the highest risk of having CD (1 in 7 and 1 in 8, respectively), the risk was 1 in 13 in sons, 1 in 16 in brothers, 1 in 32 in mothers, and 1 in 33 in fathers. There were also differences in the pooled prevalence of CD in FDRs according to their geographic location.

CONCLUSIONS

Pooled prevalence of CD among FDRs is 7.5% and varies considerably with their relationship with the index patient. The risk of CD in FDRs also varies according to gender and geographical location.

The Spectrum of Differences between Childhood and Adulthood Celiac Disease

An old saying states that ''children are not little adults" and this certainly holds true for celiac disease, as there are many peculiar aspects regarding its epidemiology, diagnosis, clinical presentations, associated diseases, and response to treatment in pediatric compared to adult populations, to such an extent that it merits a description of its own. In fact, contrary to the past when it was thought that celiac disease was a disorder predominantly affecting childhood and characterized by a malabsorption syndrome, nowadays it is well recognized that it affects also adult and elderly people with an impressive variability of clinical presentation. In general, the clinical guidelines for diagnosis recommend starting with specific serologic testing in all suspected subjects, including those suffering from extraintestinal related conditions, and performing upper endoscopy with appropriate biopsy sampling of duodenal mucosa in case of positivity. The latter may be omitted in young patients showing high titers of anti-transglutaminase antibodies. The subsequent management of a celiac patient differs substantially depending on the age at diagnosis and should be based on the important consideration that this is a lifelong condition.

European Society for Pediatric Gastroenterology, Hepatology, and Nutrition guidelines for the diagnosis of coeliac disease

OBJECTIVE

Diagnostic criteria for coeliac disease (CD) from the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) were published in 1990. Since then, the autoantigen in CD, tissue transglutaminase, has been identified; the perception of CD has changed from that of a rather uncommon enteropathy to a common multiorgan disease strongly dependent on the haplotypes human leukocyte antigen (HLA)-DQ2 and HLA-DQ8; and CD-specific antibody tests have improved.

METHODS

A panel of 17 experts defined CD and developed new diagnostic criteria based on the Delphi process. Two groups of patients were defined with different diagnostic approaches to diagnose CD: children with symptoms suggestive of CD (group 1) and asymptomatic children at increased risk for CD (group 2). The 2004 National Institutes of Health/Agency for Healthcare Research and Quality report and a systematic literature search on antibody tests for CD in paediatric patients covering the years 2004 to 2009 was the basis for the evidence-based recommendations on CD-specific antibody testing.

RESULTS

In group 1, the diagnosis of CD is based on symptoms, positive serology, and histology that is consistent with CD. If immunoglobulin A anti-tissue transglutaminase type 2 antibody titers are high (>10 times the upper limit of normal), then the option is to diagnose CD without duodenal biopsies by applying a strict protocol with further laboratory tests. In group 2, the diagnosis of CD is based on positive serology and histology. HLA-DQ2 and HLA-DQ8 testing is valuable because CD is unlikely if both haplotypes are negative.

CONCLUSIONS

The aim of the new guidelines was to achieve a high diagnostic accuracy and to reduce the burden for patients and their families. The performance of these guidelines in clinical practice should be evaluated prospectively.

Diagnosis and management of coeliac disease in children

Coeliac disease (CD) remains under diagnosed with only 10-20% of patients identified. Genes encoding HLA DQ2 or DQ8 are found in the vast majority of those with CD and testing for their presence can be useful to rule out the possibility CD. CD is more common in certain ethnic groups including those of North Indian origin. The classical presentation tends to occur in younger children, while atypical presentations occur at an older age. The number of children being diagnosed with CD is increasing; this may be due to greater recognition of the more atypical presentations, improved serologic tests, and the screening of asymptomatic groups at increased risk, but may also be due to an overall increased prevalence. Although serologic testing has become more reliable, there still remain significant problems around testing, particularly in those <18 months of age. All children should undergo a duodenal biopsy on a gluten containing diet in order to diagnose CD before recommending a gluten-free diet (GFD). A GFD should be offered to all children diagnosed with CD even when perceived as asymptomatic, as there is significant morbidity associated with CD later in life.

Cost-effective HLA typing with tagging SNPs predicts celiac disease risk haplotypes in the Finnish, Hungarian, and Italian populations

Human leukocyte antigen (HLA) genes, located on chromosome 6p21.3, have a crucial role in susceptibility to various autoimmune and inflammatory diseases, such as celiac disease and type 1 diabetes. Certain HLA heterodimers, namely DQ2 (encoded by the DQA1*05 and DQB1*02 alleles) and DQ8 (DQA1*03 and DQB1*0302), are necessary for the development of celiac disease. Traditional genotyping of HLA genes is laborious, time-consuming, and expensive. A novel HLA-genotyping method, using six HLA-tagging single-nucleotide polymorphisms (SNPs) and suitable for high-throughput approaches, was described recently. Our aim was to validate this method in the Finnish, Hungarian, and Italian populations. The six previously reported HLA-tagging SNPs were genotyped in patients with celiac disease and in healthy individuals from Finland, Hungary, and two distinct regions of Italy. The potential of this method was evaluated in analyzing how well the tag SNP results correlate with the HLA genotypes previously determined using traditional HLA-typing methods. Using the tagging SNP method, it is possible to determine the celiac disease risk haplotypes accurately in Finnish, Hungarian, and Italian populations, with specificity and sensitivity ranging from 95% to 100%. In addition, it predicts homozygosity and heterozygosity for a risk haplotype, allowing studies on genotypic risk effects. The method is transferable between populations and therefore suited for large-scale research studies and screening of celiac disease among high-risk individuals or at the population level.

Systematic review: The evidence base for long-term management of coeliac disease

BACKGROUND

While gluten-free diet is an effective treatment for coeliac disease, the need for and goals of long-term management of patients are poorly defined.

AIM

To review systematically the complications and associations of coeliac disease, to identify potential risk factors, to define ways of assessing risk factors and to provide a strategy for management.

METHODS

Review of medical literature from 1975.

RESULTS

There is an increasing list of potential complications and/or conditions associated with coeliac disease, in particular, autoimmune disease, malignancy and bone disease. Risk factors that may predict or influence long-term outcomes include genetic susceptibility, environmental factors predominantly gluten ingestion, persistent small intestinal inflammation/injury and nutritional deficiencies. Genotyping of patients is yet to have an established clinical role in long-term management. Assessment of adherence to the gluten-free diet largely relies upon skilled dietary history, but the ultimate test is duodenal histopathology, which is the only currently established means of assessing healing. Symptoms, serology or other non-invasive means are poor predictors of healing and the likelihood of complications.

CONCLUSION

Evidence (albeit limited) that adherence to a gluten-free diet and mucosal healing prevent and/or ameliorate complications indicates that a planned long-term strategy for follow-up is essential.

A one-step real-time PCR assay for detection of DQA1*05, DQB1*02 and DQB1*0302 to aid diagnosis of celiac disease

Celiac disease is an autoimmune disorder that develops after dietary exposure of the small intestine to gluten peptides in cereals. Celiac disease has a strong genetic component associated with HLA-DQ2 and HLA-DQ8, and testing for absence of these genetic markers is useful when serological tests and biopsies are indeterminate, as it renders celiac disease highly unlikely. We have developed a new real-time PCR assay, using sequence-specific primers (PCR-SSP) and TaqMan probes, for detection of DQB1*05, DQB1*02 (coding for DQ2) and DQB1*0302 (coding for DQ8). PCR amplification and detection of DQ2 and DQ8 was accurately and unambiguously performed from genomic DNA isolated from cell lines and human DNA. Amplification was scored digitally, without laboratory manipulation of amplified PCR products and with a higher accuracy than PCR-SSP. This assay should increase accuracy and throughput, and reduce risks of contamination in laboratories where testing for HLA DQ2 and DQ8 is performed as part of diagnosis of celiac disease.

Gene dose effect of the DQB1*0201 allele contributes to severity of coeliac disease

OBJECTIVE

Coeliac disease (CD) susceptibility has been shown to be associated with the HLA alleles DQA1*0501 and DQB1*0201. This HLA-associated risk has been estimated to account for 29-40% of the genetic component of CD. Conflicting data have been published on the gene dose effect of these HLA alleles on the risk and severity of CD. In this study the aim was to investigate the association between the number of HLA risk alleles and the severity of CD.

MATERIAL AND METHODS

Fifty-four Finnish CD families, including 144 CD patients mainly diagnosed in adulthood (94.4%), were enrolled in the study. The association between the number of DQA1*0501 and DQB1*0201 alleles and villous atrophy, symptoms and laboratory parameters at the time of diagnosis, and the association with villous atrophy after one year of treatment on a gluten-free diet were studied.

RESULTS

The homozygosity for the DQB1*0201 allele was associated with a more severe form of CD assessed by more severe villous atrophy (p=0.011), younger age (p=0.036), more severe diarrhoea (p=0.048) and a lower level of blood haemoglobin at the time of diagnosis (p=0.010). Furthermore, the homozygosity for the DQB1*0201 allele was associated with a slower recovery of villous atrophy after a gluten-free diet (p=0.041). In contrast, the DQA1*0501 allele did not have a significant association with the severity of CD.

CONCLUSIONS

Our results demonstrate a gene dose effect of the DQB1*0201 allele on the clinical heterogeneity of CD and on the rate of recovery from villous atrophy in patients on a gluten-free diet.

The prevalence of celiac disease in average-risk and at-risk Western European populations: a systematic review

Until recently, celiac disease (CD) was felt to be a rare disease in the United States. The aim of this study was to conduct a systematic review of the prevalence of CD in general Western populations and in populations at high risk for CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. Qualitative and quantitative prevalence estimates were produced after assessing study heterogeneity. The prevalence of CD in general Western populations is close to 1% and is somewhat higher in certain Western European populations. The prevalence of CD in populations at risk for CD is as follows: 3%-6% in type 1 diabetic patients, up to 20% in first-degree relatives, 10%-15% in symptomatic iron-deficiency anemia (IDA), 3%-6% in asymptomatic IDA, and 1%-3% in osteoporosis. The prevalence of CD in patients suspected of having CD varied depending on the reasons for suspecting CD and on whether the study was conducted in a referral center. In general, the prevalence ranged from 5% to 15%, but was up to 50% in symptomatic patients evaluated in a tertiary referral center. CD is a common medical condition. The prevalence is higher still in high-risk groups. Clinicians in a variety of specialties should have a high index of suspicion for the diagnosis of CD and in particular need to pay close attention to the identified high-risk groups.

Genomewide search and association studies in a Finnish celiac disease population: Identification of a novel locus and replication of the HLA and CTLA4 loci

It has been reported that celiac disease (CD) is strongly associated with the HLA-DQ2 alleles DQA1*0501 and DQB1*0201. However, this association only accounts for a portion of the genetic component of CD. Several non-HLA loci and candidate genes that potentially contribute to CD susceptibility have been reported, but have not been confirmed. The aim of this study was to identify loci that contribute to disease susceptibility in a CD population from Finland. We performed a genomewide linkage scan and identified two regions of significant linkage to CD (6p and 2q23-32) and one region of suggestive linkage (10p). We also performed targeted typing and analyses that replicated the associations of the HLA and CTLA4 loci.

Assessment of the DQ heterodimer test in the diagnosis of celiac disease in the Canary Islands (Spain)

BACKGROUND

Celiac disease is a multifactorial disorder of the proximal small intestine associated with a permanent intolerance to gluten. The HLA-DQ(alpha1*0501, beta1*02) heterodimer is strongly associated with this disease.

MATERIALS AND METHODS

The authors studied a sample of 354 unrelated Caucasoid individuals: 118 patients with celiac disease and 236 control subjects. All patients and controls subjects were born in Gran Canaria (Canary Islands) at least two generations ago. The authors typed the HLA-DQA1 and DQB1 genes by DNA methods. The positive and negative predictive values of the test were studied.

RESULTS

The mean age at diagnosis was 25.4 months, with a statistically significant proportion of females (64.4%, P < 0.002). For DQB1 gene, the susceptibility allele found was DQB1*02 (relative risk [RR] = 7.60, confidence interval [CI]: 5.35-10.78), whereas for the DQA1 gene, the susceptibility alleles found were DQA1*0501 (RR = 2.99, CI: 2.16-4.14) and DQA1*0201 (RR = 1.88, CI: 1.25-2.82). The presence of the DQ(alpha1*0501, beta1*02) heterodimer was strongly associated with the disease (92.4% in the patients group vs. 21.6% in control subjects). HLA-DQ8 heterodimer was absent in the authors' patients. DQB1*02 homozygous subjects presented a higher relative risk for celiac disease. There was no correlation of DQB1*02 dosage with age at onset below 12 years of age or with gender distribution. Sensitivity, specificity, and the positive and negative predictive values of the test were 92.4%, 78.4%, 68.1%, and 95.4%, respectively.

CONCLUSIONS

The presence of the DQ2 (DQA1*0501/DQB1*02) heterodimer is strongly associated with celiac disease in the population studied by the authors. The value of this test derives from its ability to exclude disease when a negative result occurs.

Genetic dissection between silent and clinically diagnosed symptomatic forms of coeliac disease in multiplex families

BACKGROUND

Coeliac disease has a large variation in clinical outcome. In addition to the classical disease with malabsorption, many individuals have a silent form, in which subject symptoms are missing but autoantibodies and mucosa lesions are identical to the symptomatic disease.

AIM

To investigate whether differences in HLA DR-DQ genes explain the variation in outcome.

MATERIALS AND METHODS

HLA DQ alleles were determined in 28 multiplex families with sibling pairs in which one had the symptomatic disease but the other had the silent form.

RESULTS

No differences in the distribution of HLA DR-DQ haplotypes could be observed. The clinically diagnosed coeliac disease seemed to have earlier onset than silent coeliac disease.

CONCLUSIONS

Results indicate that the major genetic susceptibility locus, HLA DQ, does not determine the exact clinical outcome of coeliac disease.

Endocrinological disorders and celiac disease

Celiac disease is a permanent intolerance to dietary gluten. Its well known features are abdominal symptoms, malabsorption of nutrients, and small-bowel mucosal inflammation with villous atrophy, which recover on a gluten-free diet. Diagnosis is challenging in that patients often suffer from subtle, if any, symptoms. The risk of clinically silent celiac disease is increased in various autoimmune conditions. The endocrinologist, especially, should maintain high suspicion and alertness to celiac disease, which is to be found in 2-5% of patients with insulin-dependent diabetes mellitus or autoimmune thyroid disease. Patients with multiple endocrine disorders, Addison's disease, alopecia, or hypophysitis may also have concomitant celiac disease. Similar heredity and proneness to autoimmune conditions are considered to be explanations for these associations. A gluten-free diet is essential to prevent celiac complications such as anemia, osteoporosis, and infertility. The diet may also be beneficial in the treatment of the underlying endocrinological disease; prolonged gluten exposure may even contribute to the development of autoimmune diseases. The diagnosis of celiac disease requires endoscopic biopsy, but serological screening with antiendomysial and antitissue transglutaminase antibody assays is an easy method for preliminary case finding. Celiac disease will be increasingly detected provided the close association with autoimmune endocrinological diseases is recognized.

The genetics of autoimmune polyendocrine syndrome type II

A series of autoimmune disorders, often Addison's disease, type 1 diabetes mellitus, and thyroid autoimmunity, frequently occurs together in patients with the autoimmune polyendocrine syndrome type II (APS-II). The highest risk HLA genotype for Addison's disease, either as a single disease or in APS-II patients, consists of the genotype DR3/4, DQ2/DQ8 with DRB1*0404. As many as 30% of patients with Addison's disease have this genotype versus less than 0.5% of controls. An additional and important associated locus within the HLA region is the class I related gene, MIC-A. Patients who develop Addison's disease often have a delayed diagnosis and may die from Addisonian crisis; therefore, improved genetic testing combined with testing for 21-hydroxylase autoantibodies might allow the identification of relatively high-risk populations (greater than 1 in 200 defined genetic risk compared with 1 in 10,000 population risk).

HLA-DQ typing in the diagnosis of celiac disease

OBJECTIVE

More than 95% of celiac patients share the major histocompatibility complex II class human leukocyte antigen (HLA) DQ2 or DQ8 haplotype; patients negative for both types are unlikely to suffer from celiac disease. Our aim was to investigate whether HLA-DQ2 and -DQ8 typing is helpful when diagnosis is uncertain because of the absence of unequivocal small bowel villous atrophy.

METHODS

HLA-DQ2 and -DQ8 typing was carried out in 59 patients evincing nondiagnostic small bowel mucosal lesion or positive celiac serology, and in 17 patients maintaining a gluten-free diet without biopsy-proven celiac disease. HLA findings were compared to small bowel mucosal morphology; intraepithelial lymphocytes; and serum endomysial (EmA), reticulin, tissue transglutaminase (anti-tTG) and gliadin antibodies.

RESULTS

Of the 59 patients evincing only minor small bowel mucosal changes or positive celiac disease serology, 22 (37%) were negative for DQ2 and DQ8. All EmA-positive patients had celiac-type HLA, but antireticulin antibody, anti-tTg, and antigliadin antibody were also present in HLA-DQ2- and -DQ8-negative individuals. Eleven of 17 patients (65%) observing a gluten-free diet before small bowel biopsy did not share celiac-type HLA. None of the 17 had apparent villous atrophy. Serum EmA and anti-tTG were negative in all. HLA-DQ typing is less expensive than follow-up biopsy in the exclusion of celiac disease.

CONCLUSIONS

HLA-DQ2 and -DQ8 determination is useful in exclusion, probably lifelong, of celiac disease in individuals with an equivocal small bowel histological finding. The low specificity of this test must, however, be borne in mind.

Increased density of jejunal gammadelta+ T cells in patients having normal mucosa--marker of operative autoimmune mechanisms?

Both from a clinical and a biological point of view, coeliac disease can be classified among the autoimmune diseases, or one could suspect autoimmune mechanisms to be operative in the disease. The aim of the present study was to find evidence for mucosal markers of coeliac disease latency in patients clinically suspected but on routine biopsy excluded for the disease. Monoclonal antibodies were used to stain jejunal intraepithelial lymphocytes and mucosal HLA-DR. Serum IgA-class reticulin autoantibodies were measured by an indirect immunofluorescence and gliadin antibodies by an enzyme-linked immunosorbent assay method. The DQA1*0501 and DQB1*0201 alleles were determined. Twenty-seven of 107 consecutive patients had coeliac disease. Altogether 39 of 79 (49%) children with normal jejunal mucosa had an increased density of intraepithelial gammadelta+ T cells (> or = 4.4 cells/mm). IgA-class reticulin autoantibodies were positive in 18 (23%) of the children excluded for coeliac disease. The antibody positivity was mostly seen in patients carrying the DQAI 0501 and DQB1*0201 alleles. Also, reticulin autoantibody-positive children having normal jejunal mucosal morphology had significantly higher densities of intraepithelial gammadelta+ T cells than antibody negative ones. On 1.5-4.5 year follow-up four out of 18 (22%) children primarily excluded for coeliac disease showed mucosal deterioration and coeliac disease. Many patients clinically suspected of coeliac disease but having normal jejunal mucosa show markers of coeliac disease latency which may be gluten-induced indicating autoimmune mechanisms to be operative in the gut.

Changing jejunal gamma delta T cell receptor (TCR)-bearing intraepithelial lymphocyte density in coeliac disease

The function of jejunal intraepithelial gamma delta+ T cells is obscure, but they are commonly implicated as playing a role in inflammatory and autoimmune conditions. In coeliac disease (CoD), there are controversial reports as to gluten dependency of these cells. We have now studied the small bowel mucosal intraepithelial T cell densities, and the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells during early disease development and on a gluten-free diet. Nine children initially excluded for CoD were followed up and rebiopsy after 0.8-4.5 years showed mucosal deterioration. Further, 21 biopsy specimens from newly diagnosed CoD patients were studied, together with 20 specimens taken from children on a gluten-free diet. During CoD development the density of gamma delta+ and alpha beta+ T cells as well as the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells increased. In the latent stage of CoD when the small bowel mucosal architecture was still normal, two children had clearly normal densities of gamma delta+ (< 2.5 cells/100 epithelial cells) and alpha beta+ (< 25.0 cells/100 epithelial cells) T cells, and low ratios as well. In patients with newly diagnosed CoD the densities decreased significantly on a long-term gluten-free diet. We conclude that the density of intraepithelial gamma delta+ T cells as well as alphabeta+ T cells in CoD is gluten-dependent. CoD can develop in a child ingesting normal amounts of gluten and having normal jejunal mucosal morphology on biopsy and a normal density of gamma delta+ T cells.

Celiac disease and markers of celiac disease latency in patients with primary Sjögren's syndrome

OBJECTIVE

Many autoimmune diseases occur concomitantly with celiac disease. We investigated prospectively the occurrence of celiac disease and small-bowel mucosal inflammation in patients with primary Sjögren's syndrome.

METHODS

A total of 34 patients with primary Sjögren's syndrome and 28 controls underwent small bowel biopsy. Villous morphology, jejunal intraepithelial lymphocytes, and mucosal HLA-DR were evaluated and DQA and DQB alleles, serum antiendomysial, and antigliadin antibodies were examined.

RESULTS

Five (14.7%) of 34 Sjögren's syndrome patients were found to have celiac disease. The density of jejunal intraepithelial gammadelta+ T cells was increased in all celiac and in four nonceliac patients. All celiac patients, 69% of nonceliac Sjögren's syndrome patients, and 11% of control subjects showed enhanced HLA-DR expression (p < 0.001). HLA DQ2 was present in 19 (56%) patients with Sjögren's syndrome, including all five with celiac disease.

CONCLUSIONS

The findings show a close association between Sjögren's syndrome and celiac disease. Even among nonceliac patients with primary Sjögren's syndrome, an ongoing inflammation is often present in the small bowel mucosa.

HLA-DQ2-negative celiac disease in Finland and Spain

Genetic susceptibility to celiac disease (CD) is strongly associated with DQA1*0501 and DQB1*02 (= DQ2). To study whether CD patients without DQ2 share other MHC class II or TNF alleles, we screened DQ2-negative patients in Finland and Spain. Twelve of 84 (14%) Finnish patients and 13 of 189 (6%) Spanish patients were negative for DQ2. We observed that all but two of altogether 25 DQ2-negative patients had the DR4 DQ8 haplotype, or either DQA1*0501 or DQB1*02 alone. Also, all but three were positive for DRB4*01. The only patients without any of these alleles were both positive for DR 13. There was a clear difference between Finland and Spain: Ten (83%) of the 12 Finnish DQ2-negative patients but only five (38%) of the 13 Spanish patients had DRB1*03, DQA1*03, DQB1*0302 (= DQ8) alleles. Of the Spanish patients, eight (62%) had DQB1*02 without DQA1*0501 and three (23%) had DQA1*0501 without DQB1*02. None of the TNF, TAP, or DPB1 alleles was found to be significantly associated with CD. Our results indicate that in addition to the DQ2 heterodimer, the other major risk alleles for CD are DR4 DQ8, and either DQA1*0501 or DQB1*02 alone. Patients without these alleles appear to be very rare, only two (0.7%) were identified in altogether 253 patients tested.

Circulating T lymphocyte subsets in coeliac disease (CoD) patients and healthy family members

Increased proportions of circulating antigen-primed CD45RO+ TCR gammadelta cells have been found in untreated CoD patients. As certain immunological features are now found in both CoD and healthy persons carrying the HLA DQ2 heterodimer, we sought to establish whether healthy members of the families of CoD patients who are positive for HLA DQ2 and also have increased densities of TCR gammadelta intraepithelial lymphocytes (IEL) in their small bowel mucosa have elevated levels of circulating TCR gammadelta memory cells. Peripheral blood T cells were analysed by flow cytometry in 22 patients with CoD and 16 healthy family members. Untreated CoD patients had higher percentages of circulating CD45RO+ TCR gammadelta cells and CD45RO+ Vdelta1+ cells than healthy family members. On the other hand, the amount of circulating Vdelta1+ lymphocytes was lower in patients with CoD compared with healthy family members. In contrast, no differences were found between HLA DQ2+ and HLA DQ2- healthy family members in respect of circulating TCR gammadelta cell subsets. The change in circulating TCR gammadelta cell subsets found in patients with CoD is thus a consequence of an ongoing immunological process which diminishes on a gluten-free diet rather than a phenomenon directly caused by DQ2. These changes in peripheral blood are not found in healthy individuals who have the same HLA alleles DQA1*0501 and DQB1*0201 encoding the HLA DQ2 and who also have increased densities of TCR gammadelta IEL in their otherwise normal jejunal mucosa.