An influence of HLA-A, B, DR, DQ, and MICA on the occurrence of Celiac disease in patients with type 1 diabetes

Unveiling the Link: A Comprehensive Narrative Review of the Relationship Between Type 1 Diabetes Mellitus and Celiac Disease

Type 1 diabetes mellitus (T1DM) is an autoimmune condition with a genetic predisposition. It has underlying autoimmune destruction of the pancreatic cells that produce insulin. It is often accompanied by other autoimmune conditions. This article focuses on celiac disease (CD), also an autoimmune disease. It is caused by gluten exposure. Both these conditions have genetic predisposing factors. Apart from the genetic background, aberrant small intestine immune response, inflammation, and different grades of enteropathy present in T1DM and CD are the same. With a mean frequency of 8%, the CD frequency of T1DM ranges from 3 to 16%. All T1DM patients should undergo serological testing for CD using antibodies to tissue transglutaminase at the time of T1DM onset. Individuals with T1DM and those accompanied by CD must follow a diet with no gluten. To outline the steps that can avert the development of these disorders and reduce the morbidity of the affected people, a complete understanding of the intricate pathophysiology of T1DM and its connection to CD has been undertaken in this review. The use of resources, such as PubMed and Google Scholar, has made this possible.

Type 1 Diabetes Mellitus and Autoimmune Diseases: A Critical Review of the Association and the Application of Personalized Medicine

Type 1 Diabetes Mellitus (T1DM) is a common hyperglycemic disease characterized by the autoimmune destruction of insulin-producing beta cells of the pancreas. Various attempts have been made to understand the complex interplay of genetic and environmental factors which lead to the development of the autoimmune response in an individual. T1DM is frequently associated with other autoimmune illnesses, the most common being autoimmune thyroid disorders affecting more than 90% of people with T1D and autoimmune disorders. Antithyroid antibodies are present in around 20% of children with T1D at the start of the illness and are more frequent in girls. Patients with T1DM often have various other co-existing multi-system autoimmune disorders including but not limited to thyroid diseases, parathyroid diseases, celiac disease, vitiligo, gastritis, skin diseases, and rheumatic diseases. It is a consistent observation in clinics that T1DM patients have other autoimmune disorders which in turn affect their prognosis. Concomitant autoimmune illness might affect diabetes care and manifest itself clinically in a variety of ways. A thorough understanding of the complex pathogenesis of this modern-day epidemic and its association with other autoimmune disorders has been attempted in this review in order to delineate the measures to prevent the development of these conditions and limit the morbidity of the afflicted individuals as well. The measures including antibody screening in susceptible individuals, early identification and management of other autoimmune disorders, and adoption of personalized medicine can significantly enhance the quality of life of these patients. Personalized medicine has recently gained favor in the scientific, medical, and public domains, and is frequently heralded as the future paradigm of healthcare delivery. With the evolution of the ‘omics’, the individualization of therapy is not only closer to reality but also the need of the hour.

MICA Polymorphism and Genetic Predisposition to T1D in Jordanian Patients: A Case-Control Study

Type 1 diabetes (T1D) is an autoimmune disorder whose etiology includes genetic and environmental factors. The non-classical Major Histocompatibility Complex (MHC) class I chain-related gene A (MICA) gene has been associated with increased susceptibility to T1D as the interaction of MICA to the Natural Killer Group 2D (NK2GD) receptors found on the cell surface of natural killer (NK) cells and T cells is responsible for inducing immune responses. MICA polymorphisms were reported in association with T1D among different ethnic groups. However, data from different populations revealed conflicting results, so the association of MICA polymorphisms with predisposition to T1D remains uncertain. The aim of this sequencing-based study was to identify, for the first time, the possible MICA alleles and/or genotypes that could be associated with T1D susceptibility in the Jordanian population. Polymorphisms in exons 2–4 and the short tandem repeats (STR) in exon 5 of the highly polymorphic MICA gene were analyzed. No evidence for association between T1D and MICA alleles/genotypes was found in this study, except for the MICA*011 allele which was found to be negatively associated with T1D (p = 0.023, OR = 0.125). In conclusion, MICA polymorphisms seem not to be associated with increasing T1D susceptibility in Jordanian patients.

HLA class I chain-related MICA and MICB genes polymorphism in healthy individuals from the Bulgarian population

Although human leukocyte antigen (HLA) gene polymorphism has been investigated in many populations around the world, the data on MHC class I chain-related (MIC) genes are still limited. The present study is aimed to analyze the allelic polymorphism of MICA and MICB genes and haplotype associations with HLA-B locus in 132 healthy, unrelated individuals from the Bulgarian population by next generation sequencing (NGS). A total of 36 MICA and 16 MICB alleles were observed with the highest frequency detected for MICA*008:01 (17.1%) and MICB*005:02 (32.4%). Further, two and three-loci haplotype frequencies and pairwise linkage disequilibrium were estimated. Highly significant global linkage disequilibrium was found between either HLA-B and MICA and MICB genes. This is the first study on MICA and MICB allelic polymorphism, linkage disequilibrium, and haplotype polymorphism in the Bulgarian population. These results will allow for better characterization of the genetic heterogeneity of the Bulgarian population and could contribute to further analyses on MICA and MICB clinical significance.

Distribution of MICA alleles and haplotypes associated with HLA-B in Greek population

INTRODUCTION

The Major Histocompatibility Complex Class I-related chain A gene (MICA) is a highly polymorphic functional gene located close to the HLA-B locus. Certain MICA alleles have been related to inflammatory and autoimmune diseases while MICA antibodies have been implicated in organ allograft rejection or graft-versus-host disease (GVHD).

AIM

The aim of this study was to identify the frequencies of MICA alleles and MICA ~ HLA-B haplotypes in the Greek population since, as far as we know, these data are still limited.

METHODS

DNA was obtained from 277 unrelated healthy Greek individuals of Caucasian origin, volunteer donors of blood stem cells. HLA-B* and MICA* genotyping was performed by reverse PCR-SSOP.

RESULTS

A total of 18 MICA alleles were defined in the present study. The five most frequent alleles in the Greek population were MICA*008 (24.6%), MICA*009 (22.36%), MICA*018 (16.03%), MICA*002 (8.02%) and MICA*004 (7.17%) which altogether account for 77.8% of all alleles. The most common MICA ~ HLA-B haplotypes were MICA*018 ~ B*18 (12.5%) and MICA*009 ~ B*51(11.5%).

CONCLUSIONS

The five most frequent MICA alleles in the Greek population were *008, *009, *018, *002, *004. In other Caucasian populations, two of these alleles (*008, and *004) were observed in similar frequencies. MICA*002 was observed less frequently (8.02%) in the Greek population compared to other Caucasian groups (frequencies > 15%). Also, MICA*009 and MICA*018 had elevated frequencies (above 15%) whereas in other Caucasian populations they were found around 10% or less. These data may be important for the elucidation of the role that MICA polymorphisms play in organ and stem cell transplantation and to identify the relation of certain MICA with susceptibility to specific diseases.

High-resolution genotyping of HLA class I loci in children with type 1 diabetes and celiac disease

OBJECTIVES

HLA-DQ2 and DQ8 contribute to the strongest risk haplotypes for type 1 diabetes (T1D) and celiac disease (CD). The variation in genetic risk association is likely linked to different HLA class II loci susceptibility, but association studies of HLA class I alleles are scarce. The aim was to investigate HLA class I A, B, and C alleles polymorphisms in children with only T1D, CD, and a subgroup with both T1D and CD (T1D w/CD).

MATERIALS AND METHODS

HLA class I A, B, and C genes were genotyped using next-generation targeted sequencing. A conditional analysis was performed on 68 children with T1D, 219 children with CD and seven children with T1D w/CD enrolled from a birth cohort study at high genetic risk children from the South of Sweden.

RESULTS

Among 1764 HLA class I allele variants, A*29:02:01 in T1D w/CD was associated with both T1D (OR = 21.42 [1.05, 1322.4], p = 0.0231) and CD (OR = 35 [2.36, 529.12], p = 0.0051) along with C*05:01:01 with both T1D (OR = 5.54 [1.06, 24.8], p = 0.02) and CD (OR = 6.84 [1.46, 26.01], p = 0.0077). No independent effects of HLA-B allele associations were observed in T1D w/CD.

CONCLUSION

Although the distribution of HLA class I alleles differs between children with T1D and CD, the A*29:02:01 and C*05:01:01 alleles showed shared risk association of both diseases.

HLA Haplotype Association with Celiac Disease in Albanian Pediatric Patients from Kosovo. Gastroenterol Res Pract. 2019;2019:7369014. [PMID: 31281351 PMCID: PMC6590585 DOI: 10.1155/2019/7369014]

Genetic predisposition to celiac disease (CD) is strongly associated with the presence of HLA alleles in the individual genotype encoding HLA-DQ2 and/or HLA-DQ8 heterodimers. The main aim of this study was to analyze the HLA-A, -B, -DRB1, and -DQ allele and five-locus haplotype frequencies in 60 Albanian pediatric CD patients and 124 non-CD children from Kosovo. The most prevalent haplotype in patients was the ancestral AH 8.1 haplotype present in 22.5% of the cases compared to 2.8% of the controls (P < 0.0001). Additionally, two other haplotypes were also overrepresented in patients (HLA-A^∗02~B^∗50~DRB1^∗07~DQA1^∗02:01~DQB1^∗02:02 and HLA-A^∗68~B^∗44~DRB1^∗07~DQA1^∗02:01~DQB1^∗02:02). Analysis showed that 95.0% of CD patients and 43.3% of controls were carriers of HLA-DQ2 and/or HLA-DQ8 heterodimers. The most frequent CD-predisposing HLA-DQ haplotypes in patients were HLA-DQ2.5 (46.7%) and HLA-DQ2.2 (11.6%), while the most prevalent genotypes were HLA-DQ2.5/DQX (58.3%) and HLA-DQ2.5/DQ2.2 (20.0%). The frequency of the HLA-DQ8 heterodimer among CD patients (4.2%) compared to the control group (8.1%) was without statistical significance. The given data demonstrate differences in the distribution of HLA haplotypes among Albanian CD patients from Kosovo in comparison to other European and non-European populations, as well as provide additional population data to supplement the thus far undisputed importance of the role of HLA-DQ2 and HLA-DQ8 heterodimers in the development of CD.

The incidence of spondyloarthritis in Slovenia

Epidemiological studies of spondyloarthritides (SpA) are rare and data for our country are lacking. We aimed to determine the incidence of SpA in a well-defined region in Slovenia.We performed a retrospective chart review of adults diagnosed with SpA between January 2014 and December 2016 at an integrated secondary/tertiary medical center, which provides rheumatology services to almost a half of the adult national population, that is, 700,000 adults. Potential cases were ascertained by searching the electronic medical records for ICD-10 codes M02, M07, M13, M45, M 46.1, K50, K51, and L40. SpA cases were stratified as axial and peripheral SpA and then the annual incidence rates of SpA overall and both subsets were estimated.During the 3-year period we identified 302 SpA cases (55.0% males, median [interquartile range] age 46.7 [35.0-57.5] years). 98 (32.5%) of them had predominantly axial SpA and the remainder peripheral SpA. The estimated annual incidence rate per 100,000 adults in our region was 14.3 (95% confidence interval [CI] 12.8-16.0) for SpA overall, 4.6 (95% CI 3.8-5.6) for axial SpA, and 9.6 (95% CI 8.4-11.1) for peripheral SpA.The estimated annual incidence rate of 14.3 cases per 100,000 adults in SpA overall was comparable to that of rheumatoid arthritis in our population. The peripheral SpA was twice as common as axial SpA.

Autoimmune diseases and 8.1 ancestral haplotype: An update

The aim of the present review is to provide an update of the current research into the pathogenesis of autoimmune diseases associated with 8.1 ancestral haplotype. This is a common Caucasoid haplotype carried by most people who type for HLA-B8, DR3. Numerous genetic studies reported that individuals with certain HLA alleles have a higher risk of specific autoimmune disorders than those without these alleles. However, much remains to be learned about the heritability of autoimmune conditions. Recently, progress and advances in the field of genome-wide-association studies have revolutionized the capacity to perform large, economically feasible, and statistically robust analyses of HLA within 8.1 ancestral haplotype, and understand its contribute to autoimmune events. In this paper, the characteristic features of this haplotype that might give rise to diverse autoimmune phenotypes are reviewed, focusing on the contribution of the HLA-DRB1 gene, the most polymorphic sequence within the HLA II region.

A quarter of patients with type 1 diabetes have co-existing non-islet autoimmunity: the findings of a UK population-based family study

Individuals with type 1 diabetes (T1D) are at increased risk of coeliac disease (CD), autoimmune thyroiditis and autoimmune gastritis, but the absolute risks are unclear. The aim of this study was to investigate the prevalence of autoantibodies to tissue transglutaminase (TGA), thyroid peroxidase (TPOA) and gastric H⁺ /K⁺ -ATPase (ATPA) and their genetic associations in a well-characterized population-based cohort of individuals with T1D from the Bart's-Oxford family study for whom islet autoantibody prevalence data were already available. Autoantibodies in sera from 1072 patients (males/females 604/468; median age 11·8 years, median T1D duration 2·7 months) were measured by radioimmunoassays; HLA class II risk genotype was analysed in 973 (91%) using polymerase chain reaction with sequence specific primers (PCR-SSP). The prevalence of TGA (and/or history of CD), TPOA and ATPA in patients was 9·0, 9·6 and 8·2%, respectively; 3·1% had two or more autoantibodies. Females were at higher risk of multiple autoimmunity; TGA/CD were associated with younger age and TPOA with older age. ATPA were uncommon in patients under 5 years, and more common in older patients. Anti-glutamate decarboxylase autoantibodies were predictive of co-existing TPOA/ATPA. TGA/CD were associated with human leucocyte antigen (HLA) DR3-DQ2, with the DR3-DQ2/DR3-DQ2 genotype conferring the highest risk, followed by DR4-DQ8/DR4-DQ8. ATPA were associated with DR3-DQ2, DRB1*0404 (in males) and the DR3-DQ2/DR4-DQ8 genotype. TPOA were associated with the DR3-DQ2/DR3-DQ2 genotype. Almost one-quarter of patients diagnosed with T1D aged under 21 years have at least one other organ-specific autoantibody. HLA class II genetic profiling may be useful in identifying those at risk of multiple autoimmunity.

How Mucosal Epithelia Deal with Stress: Role of NKG2D/NKG2D Ligands during Inflammation

Mucosal epithelia encounter both physicochemical and biological stress during their life and have evolved several mechanisms to deal with them, including regulation of immune cell functions. Stressed and damaged cells need to be cleared to control local inflammation and trigger tissue healing. Engagement of the activating NKG2D receptor is one of the most direct mechanisms involved in the recognition of stressed cells by the immune system. Indeed, injured cells promptly express NKG2D ligands that in turn mediate the activation of lymphocytes of both innate and adaptive arms of the immune system. This review focuses on different conditions that are able to modulate NKG2D ligand expression on the epithelia. Special attention is given to the mechanisms of immunosurveillance mediated by natural killer cells, which are finely tuned by NKG2D. Different types of stress, including viral and bacterial infections, chronic inflammation, and cigarette smoke exposure, are discussed as paradigmatic conditions for NKG2D ligand modulation, and the implications for tissue homeostasis are discussed.

Co-occurrence of Type 1 Diabetes and Celiac Disease Autoimmunity

BACKGROUND AND OBJECTIVES

Few birth cohorts have prospectively followed development of type 1 diabetes (T1D) and celiac disease (CD) autoimmunities to determine timing, extent of co-occurrence, and associated genetic and demographic factors.

METHODS

In this prospective birth cohort study, 8676 children at high genetic risk of both diseases were enrolled and 5891 analyzed in median follow-up of 66 months. Along with demographic factors and HLA-DR-DQ, genotypes for HLA-DPB1 and 5 non-HLA loci conferring risk of both T1D and CD were analyzed.

RESULTS

Development of persistent islet autoantibodies (IAs) and tissue transglutaminase autoantibodies (tTGAs), as well as each clinical disease, was evaluated quarterly from 3 to 48 months of age and semiannually thereafter. IAs alone appeared in 367, tTGAs alone in 808, and both in 90 children. Co-occurrence significantly exceeded the expected rate. IAs usually, but not always, appeared earlier than tTGAs. IAs preceding tTGAs was associated with increasing risk of tTGAs (hazard ratio [HR]: 1.48; 95% confidence interval [CI]: 1.15-1.91). After adjusting for country, sex, family history, and all other genetic loci, significantly greater co-occurrence was observed in children with a T1D family history (HR: 2.80), HLA-DR3/4 (HR: 1.94) and single-nucleotide polymorphism rs3184504 at SH2B3 (HR: 1.53). However, observed co-occurrence was not fully accounted for by all analyzed factors.

CONCLUSIONS

In early childhood, T1D autoimmunity usually precedes CD autoimmunity. Preceding IAs significantly increases the risk of subsequent tTGAs. Co-occurrence is greater than explained by demographic factors and extensive genetic risk loci, indicating that shared environmental or pathophysiological mechanisms may contribute to the increased risk.

Effect of Associated Autoimmune Diseases on Type 1 Diabetes Mellitus Incidence and Metabolic Control in Children and Adolescents

Type 1 diabetes mellitus (T1DM) is one of the most common chronic diseases developing in childhood. The incidence of the disease in children increases for unknown reasons at a rate from 3 to 5% every year worldwide. The background of T1DM is associated with the autoimmune process of pancreatic beta cell destruction, which leads to absolute insulin deficiency and organ damage. Complex interactions between environmental and genetic factors contribute to the development of T1DM in genetically predisposed patients. The T1DM-inducing autoimmune process can also affect other organs, resulting in development of additional autoimmune diseases in the patient, thereby impeding diabetes control. The most common T1DM comorbidities include autoimmune thyroid diseases, celiac disease, and autoimmune gastritis; additionally, diabetes can be a component of PAS (Polyglandular Autoimmune Syndrome). The aim of this review is to assess the prevalence of T1DM-associated autoimmune diseases in children and adolescents and their impact on the course of T1DM. We also present suggestions concerning screening tests.

Genetics, genomics, and evolutionary biology of NKG2D ligands

Human and mouse NKG2D ligands (NKG2DLs) are absent or only poorly expressed by most normal cells but are upregulated by cell stress, hence, alerting the immune system in case of malignancy or infection. Although these ligands are numerous and highly variable (at genetic, genomic, structural, and biochemical levels), they all belong to the major histocompatibility complex class I gene superfamily and bind to a single, invariant, receptor: NKG2D. NKG2D (CD314) is an activating receptor expressed on NK cells and subsets of T cells that have a key role in the recognition and lysis of infected and tumor cells. Here, we review the molecular diversity of NKG2DLs, discuss the increasing appreciation of their roles in a variety of medical conditions, and propose several explanations for the evolutionary force(s) that seem to drive the multiplicity and diversity of NKG2DLs while maintaining their interaction with a single invariant receptor.

High-risk genotypes HLA-DR3-DQ2/DR3-DQ2 and DR3-DQ2/DR4-DQ8 in co-occurrence of type 1 diabetes and celiac disease

Shared susceptibility alleles in the HLA region contribute to the co-existence of type 1 diabetes (T1D) and celiac disease (CD). The aim of our study was to identify HLA genotype variations that influence co-occurrence of T1D and CD (T1D + CD) and the order of their onset. Totally 244 patients, 67 with T1D, 68 with CD and 69 with T1D + CD, (split into "T1D first" and "CD first"), were analyzed. Control group consisted of 130 healthy unrelated individuals. Two-tailed Fisher's exact test was used for statistical analysis. The genetic background of Slovenian CD patients resembled more northern than southern European populations with DR3-DQ2/DR3-DQ2 (odds ratio [OR] = 19.68) conferring the highest risk. The T1D + CD was associated with DR3-DQ2/DR3-DQ2 (OR = 45.53) and even more with DR3-DQ2/DR4-DQ8 (OR = 93.76). DR3-DQ2/DR7-DQ2 played a neutral role in susceptibility for T1D + CD. The order of the onset of T1D or CD in patients with co-occurring diseases was not influenced by HLA risk genotype profile. DR3-DQ2/DR3-DQ2 was associated with an increased risk for developing CD in patients with T1D, whereas patients with CD carrying DR3-DQ2/DR4-DQ8 were at higher risk for developing T1D. In addition to other genetic factors including HLA class I alleles present on DR3-DQ2 extended haplotype, the second extended haplotype may moderate the risk for T1D + CD conferred by DR3-DQ2. Our results suggested that individuals carrying high-risk genotypes DR3-DQ2/DR3-DQ2 or DR3-DQ2/DR4-DQ8 would more likely develop both T1D and CD than either disease alone.

HLA-DQ genetic risk gradient for type 1 diabetes and celiac disease in northwestern Mexico

BACKGROUND

Type 1 diabetes (T1D) and celiac disease (CD) are the 2 most common autoimmune childhood diseases that share their HLA-DQ2 and DQ8 genetic origin. There has currently been an increase in both diseases worldwide. In children from the low-population State of Sonora (15 inhabitants/km(2)) in north-western Mexico, there is no information on their genetic risk or the distribution of the related alleles in the general population.

AIMS

To compare the HLA-DQ allele frequency in a representative sample of newborns from Sonora with that of T1D and CD patients to determine the risk gradient, and to identify the presence of celiac autoimmunity in the T1D group.

METHODS

The study included 397 Sonoran newborns, with 44 cases of T1D, and 25 CD cases. The CD and T1D cases were clinically diagnosed by specialists at the Hospital Infantil del Estado de Sonora, and the autoantibodies were determined by ELISA. Whole blood was collected, gDNA was extracted, and HLA-DQ2 and DQ8 were typed by PCR-SSP. The risk gradient was calculated by comparing the allele frequencies of the cases with those of the newborns.

RESULTS

The Sonoran HLA-DQ risk heterodimer proportion was 16.1% for HLA-DQ2 and 13.6% for HLA-DQ8, with an HLA-DQ2:HLA-DQ8 ratio of 1.2:1. The DQ8/DQ2 genotype represented a 1:14 risk for T1D, whereas the DQ8/DQB1*0201 combination showed a 1:6 risk for CD. The prevalence of CD autoimmunity in T1D children was 7%.

CONCLUSION

The Sonoran population has a distinctive HLA-DQ allele distribution due to its ancestry. The HLA-DQ8 combinations with DQ2 or one of its alleles conferred the highest risk for both diseases, and T1D and CD frequently appear together.

Type 1 Diabetes in the Young: Organization of Two National Centers in Israel and Slovenia

Type 1 diabetes is a chronic autoimmune disease that affects mainly young people. In the last 50 years, a steady increase of the T1D incidence in the young is reported worldwide, with an average 4 % increase annually. In addition, the mean age at the diagnosis is decreasing. Studies show that good metabolic control is important not only for delaying the chronic complications of diabetes but also for improving the quality of life of patients and their families. Continuous education, together with modern technology, is crucial in achieving these goals. Longitudinal data on glycated hemoglobin (HbA1c), along with the data on severe hypoglycemia and severe diabetic ketoacidosis, can describe the quality of care in a defined population. Two national reference diabetes centres taking care of children, adolescents and young adults with diabetes in Israel and Slovenia are described.

Evaluation of European coeliac disease risk variants in a north Indian population

Studies in European populations have contributed to a better understanding of the genetics of complex diseases, for example, in coeliac disease (CeD), studies of over 23 000 European samples have reported association to the HLA locus and another 39 loci. However, these associations have not been evaluated in detail in other ethnicities. We sought to better understand how disease-associated loci that have been mapped in Europeans translate to a disease risk for a population with a different ethnic background. We therefore performed a validation of European risk loci for CeD in 497 cases and 736 controls of north Indian origin. Using a dense-genotyping platform (Immunochip), we confirmed the strong association to the HLA region (rs2854275, P=8.2 × 10⁻⁴⁹). Three loci showed suggestive association (rs4948256, P=9.3 × 10⁻⁷, rs4758538, P=8.6 × 10⁻⁵ and rs17080877, P=2.7 × 10⁻⁵). We directly replicated five previously reported European variants (P<0.05; mapping to loci harbouring FASLG/TNFSF18, SCHIP1/IL12A, PFKFB3/PRKCQ, ZMIZ1 and ICOSLG). Using a transferability test, we further confirmed association at PFKFB3/PRKCQ (rs2387397, P=2.8 × 10⁻⁴) and PTPRK/THEMIS (rs55743914, P=3.4 × 10⁻⁴). The north Indian population has a higher degree of consanguinity than Europeans and we therefore explored the role of recessively acting variants, which replicated the HLA locus (rs9271850, P=3.7 × 10⁻²³) and suggested a role of additional four loci. To our knowledge, this is the first replication study of CeD variants in a non-European population.

Association study of MICA-TM polymorphism with inflammatory bowel disease in the South Tunisian population

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory disorders of the gastro-intestinal tract with unknown etiology. Both environmental and genetic factors are involved in the pathogenesis of these inflammatory bowel diseases (IBD).

AIM

The purpose of the present study was to determine the association between the polymorphism of the transmembrane region of MICA (MICA-TM), and the genetic susceptibility in Tunisian patients with IBD.

PATIENTS AND METHODS

A total of 102 Tunisian patients (66 with UC, 36 with CD) and 123 healthy controls were enrolled in our study. MICA-TM was genotyped by a semiautomatic fluorescent-labelled PCR method, amplicons were analysed on an ABI Prism 310 genotyper. Comparisons of allele frequencies between patients and controls, and between patients' subgroups were performed using SPSS 13.0.

RESULTS

No MICA allele was significantly increased in both groups of IBD compared to controls. The MICA-A5.1 allele was significantly decreased in CD patients (p=0.006, pc=0.03). In UC, MICA-A6 was associated with the presence of extraintestinal manifestations (p=0.04, pc=0.2), whereas MICA-A5 was associated with late age of onset (p=0.04). In CD, MICA-A6 was significantly increased in active disease patients when compared to moderately active or inactive disease (p=0.03, pc=0.15).

CONCLUSION

Some clinical features of CD and UC may be influenced by specific MICA-TM alleles. In our South Tunisian population, MICA plays a disease modifying role, rather than being an important gene in the susceptibility for developing IBD.

Common immunogenetic profile in children with multiple autoimmune diseases: the signature of HLA-DQ pleiotropic genes

Type 1 diabetes mellitus (T1DM), celiac disease (CD) and autoimmune thyroid disease (ATD) are autoimmune conditions relatively common in paediatric age and frequently occur in association in the same subject. This event is not by chance and requires an explanation. Here, we studied the distribution of HLA-DQ αβ heterodimers in 334 Italian children with T1DM, ATD and CD alone or in association and in 224 Italian healthy controls. In particular, 164 patients had T1DM (133 alone, 20+ATD, 7+CD and 4+CD+ATD), 118 had ATD (110 alone, 8+CD) and 52 had CD (40 alone, 11+ATD and 1+T1DM). 51 patients suffered from multiple autoimmune diseases. The risk for multiple autoimmune diseases was significantly associated with the increased number of HLA-DQ markers of susceptibility for both T1DM (p = 0.003) and CD (p = 0.006). The presence of one or more diabetogenic DQ molecules significantly increased the probability of developing not only T1DM (p < 0.001) but also CD (p < 0.001) and ATD (p = 0.001). Similarly, the presence of one or more celiac HLA-DQ heterodimers significantly increased the likelihood of developing not only CD (p < 0.001), but also T1DM (p < 0.001) and ATD (p < 0.001). We confirm that the sharing of the immunogenetic background is responsible for the development of multiple autoimmune diseases although with a different risk according to the number and type of susceptible HLA-DQ heterodimers as reported in the algorithm proposed here. It is likely that combinations of DQA1 and DQB1 alleles are the real culprits of the progression towards multiple autoimmune diseases and HLA-DQ genomic typing will improve the capability to predict associated autoimmune diseases in infancy.

What is the key environmental trigger in type 1 diabetes--is it viruses, or wheat gluten, or both?

Prevention and treatment of type 1 diabetes is hampered by the fact that the key environmental trigger(s) of the disease is still unknown. Much of the data on this subject points to two possibilities, viruses and wheat gluten. Viruses appear to be involved as an etiological agent in some cases of type 1 diabetes, particularly in fulminant type 1 diabetes. Further analysis of the data suggests that viruses are not the sole trigger of type 1 diabetes in humans, and that wheat gluten may play a role in initiating the disease. Viruses may be the key environmental trigger in some cases of type 1 diabetes, and wheat gluten in others. Conceivably, some cases of type 1 diabetes might be caused by viruses and wheat gluten acting together as disease triggers.

Shared genetics in coeliac disease and other immune-mediated diseases

Identifying disease-associated variants can improve the predictive models of disease risk and provide mechanistic insights into disease development. Coeliac disease (CD) is the only autoimmune trait with a known environmental trigger, which makes it an excellent model for studying the complexity of genetic and environmental factors in the development of autoimmunity. In this review, we will focus on the genetic loci that have recently been associated with CD and that contain genes involved in innate and adaptive immunity. Some of these loci are shared with other immune-mediated diseases, suggesting an overlap of the genetic mechanisms involved in the development of such diseases. Some therapies, e.g. tumour necrosis factor inhibitors or a gluten-free diet, are already proving effective for more than one autoimmune disease. Follow-up of individuals with a high genetic risk of CD and other autoimmune diseases could help to elucidate the role of environmental factors (such as infectious agents or alterations in the microbiome) and prevent disease development.

Coexistent autoimmunity in familial type 1 diabetes: increased susceptibility in sib-pairs?

BACKGROUND

Type 1 diabetes (T1D) patients are at risk for additional autoimmune diseases (AID).

OBJECTIVE

To compare the characteristics of associated autoimmunity among familial (parent-offspring and sib-pair) subgroups and sporadic T1D patients.

PATIENTS AND METHODS

Data regarding AID in T1D patients and their nuclear family members were extracted from medical files of 121 multiplex T1D families (58 parent-offspring, 63 sib-pairs) and 226 sporadic controls followed between 1979 and 2008.

RESULTS

The prevalence of associated autoimmunity was similar in familial and sporadic cases (33.6 vs. 32.7%). The frequency of additional AID and percentage of patients with two or more coexistent AID were significantly higher among sib-pairs than parent-offspring (p = 0.05 and p = 0.04, respectively). The median time elapsed between diagnosis of T1D and occurrence of additional autoimmunity tended to be shorter in the sib-pairs. Only in familial cases did a positive autoimmune family background predict the development of coexistent autoimmunity (OR = 2.11, CI [1.0, 4.49] p = 0.05).

CONCLUSIONS

Among sib-pairs with T1D, the higher prevalence of additional AID, the increased number of diseases per person, and the relatively earlier appearance of associated AID suggest an increased susceptibility for coexistent autoimmunity in this subgroup. Positive family history for autoimmunity in multiplex T1D families increased their risk for co-occurrence of AID.