人白细胞抗原DQ单体型对特发性1型糖尿病免疫病因分型的意义

目的 通过对临床特征、锌转运体8自身抗体（ZnT8A）、分泌干扰素γ的谷氨酸脱羧酶65反应性T细胞（GAD65-IFN-γ-T细胞）检测情况的比较,探讨人白细胞抗原（HLA） DQ单体型对初诊特发性1型糖尿病免疫病因分型的价值.方法 将2000年3月至2011年12月收治的52例自发酮症或酮症酸中毒起病,谷氨酸脱羧酶抗体（GADA）、蛋白酪氨酸磷酸酶抗体（IA-2A）及胰岛素自身抗体（IAA）均阴性,且依赖胰岛素治疗的湖南省汉族新发1型糖尿病患者纳入本研究.放射配体法检测锌转运体8自身抗体（ZnT8A）,酶联免疫斑点技术（ELISPOT）检测GAD65-IFN-γ-T细胞,聚合酶链反应（PCR）直接测序法测定HLA-DQ基因型.将研究对象分为HLA-DQ易感单体型携带组和HLA-DQ易感单体型不携带组,并以1年为间隔随访3年.比较两组起病初期的临床特征、ZnT8A及GAD65-IFN-γ-T细胞检测情况,随访时胰岛自身抗体的变化.两组间计数资料比较采用x2检验.结果 52例初诊特发性1型糖尿病患者中5例ZnT8A阳性,阳性率9.6％;16例ZnT8A阴性且接受GAD65-IFN-γ-T检测的患者中,2例GAD65-IFN-γ-T阳性,阳性率12.5％.与HLA-DQ易感单体型不携带组相比,携带组起病初期酮症程度更严重（Z=-2.84,P＜0.05）,空腹C肽水平更低（x2 =0.38,P＜0.05）.起病初期,携带组中1例患者GAD65-IFN-γ-T细胞检测呈阳性反应（1/5）,而不携带组未检测到该细胞呈阳性患者.随访时,携带组中1例患者ZnT8A和IA-2A由阴转阳（1/18）,不携带组中未有检测到抗体转阳患者.结论 部分特发性1型糖尿病患者体内存在ZnT8A和GAD65-IFN-γ-T细胞;携带HLA-DQ易感单体型的特发性1型糖尿病患者,较不携带者更加具有自身免疫倾向.胰岛自身免疫是部分初诊特发性1型糖尿病的病因,可能通过HLA-DQ单体型介导.     

Human leukocyte antigen DR status and clinical features in Japanese patients with type 1 autoimmune hepatitis.

Aim: Human leukocyte antigen (HLA) DR status affects the clinical features of autoimmune hepatitis. In Caucasians, patients with DR3 have poorer outcomes. In Japan, the relationship between HLA DR status and clinical features has yet to be fully examined. Methods: We investigated 79 patients with type 1 autoimmune hepatitis who underwent liver biopsy and were screened for HLA DR status by the polymerase chain reaction sequence specific oligonucleotide hybridization method. Results: Fifty-five patients had DR4 and 23 had DR2. Thirteen patients had both DR2 and DR4. None had DR3. Of patients aged <30 years, 70% did not have DR4. A tendency toward higher serum levels of immunoglobulin G was seen in patients with DR4 compared to those without, while patients with neither DR2 nor DR4 had lower serum levels of immunoglobulin G than those with only DR2 and those with only DR4. Patients with DR2 had a lower frequency of concurrentautoimmune disease. Concurrence of thyroid disease was seen only in patients with DR4. The cumulative incidental rate of the normalization of serum alanine aminotransferase levels within six months after the introduction of corticosteroid treatment was not associated with HLA DR status. Conclusion: HLA DR status is considered to affect the clinical features of Japanese patients with type 1 autoimmune hepatitis. Japanese patients with DR2 may have different clinical features from others. In addition, diagnoses of type 1 autoimmune hepatitis should be made carefully in Japanese patients with neither DR2 nor DR4 and in those aged <30 years.     

Human leukocyte antigen haplotypes and HFE mutations in Spanish hereditary hemochromatosis and sporadic porphyria cutanea tarda

BACKGROUND AND AIMS: It has been postulated that the HFE C282Y mutation (linked to human leukocyte antigen [HLA]-A3-B7 haplotype) is not only responsible for hereditary hemochromatosis; HLA class I alleles would also contribute to the disease pathogenesis. In addition, H63D mutation linked to HLA-A29-B44 would also be pathogenetic, particularly in the Mediterranean Basin and throughout the world. However, sporadic porphyria cutanea tarda (s-PCT) has also been linked to these HFE mutations. In the present work, we have studied HFE mutations and HLA genes to test these hypotheses. METHODS: C282Y and H63D mutations together with HLA genetic typing have been performed in Spanish hereditary hemochromatosis (n = 98) and PCT (n = 63) patients. The etiologic fraction (delta) has been used to determine the absolute strongest gene linkage to both diseases. RESULTS: The Spanish frequent HLA-A29-B44 haplotype is not significantly associated to the H63D mutations in hereditary hemochromatosis patients (although it is found more frequently in patients than in controls). Sporadic porphyria cutanea tarda patients do not show a significant association to H63D mutations, although it is also more frequent than in controls; however, compound H63D/C282Y subjects seem to bear a significant risk to s-PCT. Allelic C282Y (and not H63D) frequencies show a significant association with s-PCT. CONCLUSIONS: The postulated additional risk of hereditary hemochromatosis given by class I HLA antigens may be secondary to the HFE gene linkage disequilibrium with certain class I alleles or to the existence of other neighboring genetic pathogenetic factors in our Spanish sample.     

Rare human leukocyte antigen genotype in two siblings with type 1 diabetes in a Japanese family clustered with type 1 diabetes

Multiplex families with type 1 diabetes are important for identification of rare variants that cannot be identified in case–control association studies. The very low incidence of type 1 diabetes in the Japanese population, however, makes identification of such families difficult. We identified a Japanese family in which three members developed type 1 diabetes, and studied the genotype of the human leukocyte antigen. All three members with type 1 diabetes had the DRB1*08:02‐DQB1*03:02 haplotype, which is specific to the Asian population and strongly susceptible for type 1 diabetes. In particular, a proband and his sister had the same genotype, DRB1*08:02‐DQB1*03:02/DRB1*08:02‐DQB1*03:02, which is extremely rare even in the Japanese population. Both parents also had DRB1*08:02‐DQB1*03:02, but in combination with different human leukocyte antigen haplotypes. Weakly susceptible DRB1*13:02‐DQB1*06:04 was present in the affected mother, and resistant DRB1*15:01‐DQB1*06:02 in the unaffected father. These data suggest DRB1*08:02‐DQB1*03:02 to be a contributing factor for familial clustering of type 1 diabetes in this family.     

Human leukocyte antigen DQ2/8 prevalence in non-celiac patients with gastrointestinal diseases

AIM: To investigate the prevalence of human leukocyte antigen (HLA) DQ2/8 alleles in Southern Italians with liver and gastrointestinal (GI) diseases outside of celiac disease. METHODS: HLA DQ2/8 status was assessed in 443 patients from three ambulatory gastroenterology clinics in Southern Italy (University of Federico Ⅱ, Naples, Loreto Crispi Hospital, Ruggi D’Aragona Hospital, Salerno). Patients were grouped based on disease status [pre-post transplant liver disease, esophageal/gastric organic and functional diseases, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD)] and DQ2/8 alleles, which correspond to a celiac disease genetic risk gradient. Subject allele frequencies were compared to healthy Italian controls. RESULTS: One hundred and ninety-six out of four hundred and forty-three (44.2%) subjects, median age 56 years and 42.6% female, were DQ2/8 positive. When stratifying by disease we found that 86/188 (45.7%) patients with liver disease were HLA DQ2/8 positive, 39/73 (53.4%) with functional upper GI diseases and 19/41 (46.3%) with organic upper GI diseases were positive. Furthermore, 38/105 (36.2%) patients with IBS and 14/36 (38.9%) with IBD were HLA DQ2/8 positive (P = 0.21). Compared to healthy controls those with functional upper GI diseases disorders had a 1.8 times higher odds of DQ2/8 positivity. Those with liver disease had 1.3 times the odds, albeit not statistically significant, ofDQ2/8 positivity. Both those with IBS and IBD had a lower odds of DQ2/8 positivity compared to healthy controls. CONCLUSION: The proportion of individuals HLA DQ2/8 positive is higher in those with liver/upper functional GI disease and lower in IBS/IBD as compared to general population estimates.     

Human leukocyte antigen (HLA) class I antibodies and transfusion support in paediatric HLA-matched haematopoietic cell transplant for sickle cell disease

The relevance of donor-specific human leukocyte antigen (HLA) antibodies in HLA-mismatched haematopoietic cell transplant (HCT) is known, but the importance of HLA antibodies in HLA-matched HCT is unclear. We hypothesized that HLA antibodies detected before HCT would cause platelet transfusion refractoriness during HCT and investigated this in a multi-centre study. Pre-HCT samples from 45 paediatric patients with sickle cell disease (SCD) undergoing HLA-matched HCT were tested for HLA class I antibodies. The number of platelet transfusions received before day +45 was compared between those with and without antibodies. Thirteen of 45 (29%) patients had a positive HLA class I antibody screen, and these patients received significantly more platelet transfusions than patients without antibodies (median 19 vs. 7·5, P = 0·028). This platelet transfusion association remained significant when controlling for conditioning regimen. Among alloimmunized patients, there was no association between the panel-reactive antibody and the number of platelet transfusions. Patients with HLA class I antibodies also had a higher incidence of acute graft-versus-host disease (GVHD): 6/13 (46%) vs. 3/32 (9%), P = 0·011. Pre-HCT HLA class I alloimmunization is associated with increased platelet transfusion support and acute GVHD in paediatric HLA-matched HCT for SCD. Further studies are needed to investigate the pathobiology of this association.     

Prevalence and clinical profile of celiac disease in type 1 diabetes mellitus in north India

Background and Aim: There is scanty data on the occurrence of celiac disease in patients with type 1 diabetes mellitus in South Asia. Our aim was to study the prevalence and clinical profile of celiac disease in patients with type 1 diabetes mellitus in a tertiary care referral centre in north India. Methods: Consecutive patients of type 1 diabetes mellitus attending the Endocrine clinic of our institute between January 2002 and December 2008 were screened using anti‐tissue transglutaminase antibodies (tTGAb), and those positive were subjected to duodenal biopsy. Clinical profile of these patients was recorded. Results: Out of 189 patients of type 1 diabetes mellitus, 21 (11.1%) were diagnosed to have celiac disease on the basis of positive serology (tTGAb) and duodenal histology. The mean age at diagnosis of diabetes was 10.81 ± 7.3 years and that of celiac disease was 13.74 ± 5.71 years, with a difference of 5.18 ± 4.75 years between the two. Only 2/21 patients with celiac disease had been diagnosed before detection of diabetes mellitus. Short stature was the commonest (52.3%) manifestation of celiac disease, followed by anemia (47.3), weight loss (42.8%), diarrhea (28.6%) and abdominal pain (14.2%). After initiating gluten free diet, 14/16 symptomatic patients had reversal of anemia, weight loss and diarrhea. Growth rate velocity improved from 2.3 ± 1.0 cm/year to 5.5 ± 2.4 cm/year in those with short stature. Conclusion: Celiac disease is highly prevalent in patients with type 1 diabetes mellitus (11.1%) and majority of them (90.5%) were diagnosed on screening. Routine screening is required for early diagnosis and combat associated co‐morbidities.     

Exercise is not associated with better diabetes control in type 1 and type 2 diabetic subjects

In the clinical setting, the impact of educational efforts on the amount of regular exercise and its effects on diabetes control are unclear. Fifty type 1 diabetic, 50 type 2 diabetic and 70 non-diabetic subjects were evaluated using a questionnaire for type, duration and intensity of exercise to assess weekly energy expenditure. Diabetic subjects did not exercise more than controls: 36% of the type 1, 46% of the type 2 and 46% of the control subjects admitted no physical activity, and those exercising regularly had similar energy expenditure: 1808±320, 2722±617, 2523±304 (mean±SEM) kcal/week respectively (P=NS). There was no correlation between the degree of activity and HbA_1c levels, or hypoglycaemic events. HbA_1c levels were less than 6,8% in 31% of non-active active patients versus 21% of active patients (P=NS). A negative correlation was found between physical activity and daily insulin usage (r=0.27,P<0.05), but differences between patients averaged only 4 IU/1000 kcal energy expenditure/day. We conclude that patients' attitude towards exercise was not improved by our educational methods and that physical exercise was not necessarily associated with good blood glucose control.     

Recent findings on fulminant type 1 diabetes

Fulminant type 1 diabetes (fT1D) is a new subtype of type 1 diabetes proposed by Imagawa in 2000. It is a clinical syndrome characterized by a markedly rapid and almost complete destruction of pancreatic β cells. Metabolic derangement is more severe in this subtype than in autoimmune type 1 diabetes. The incidence of fT1D is associated with HLA DRB1*04:05DQB1*04:01; both innate and acquired immune disorders might contribute to the development of fT1D. The presence of specific innate immune responses to enterovirus infection connected with enhanced adaptive immune pathways responsible for aggressive β cell toxicity in fT1D. The process of β cell destruction is extremely rapid in fT1D, and the insulin secretary capacity rarely recovers after the onset. The serum glycated albumin to glycated haemoglobin ratio is significantly higher in fT1D; a cut‐off value of 3.2 for serum glycated albumin to glycated haemoglobin ratio yielded 97% sensitivity and 98% specificity for differentiating fT1D from type 2 diabetes. Fulminant type 1 diabetes is associated with pregnancy. This article also updates the diagnostic criteria for fT1D by the Japanese Diabetes Association in 2012.     

A retroviral long terminal repeat adjacent to the HLA DQB1 gene (DQ-LTR13) modifies Type I diabetes susceptibility on high risk DQ haplotypes

Aims/hypothesis: HLA-DQ genes, located in the human leukocyte antigen region on chromosome 6 p, are the main inherited factors predisposing to Type I (insulin-dependent) diabetes mellitus. Endogenous retroviral long-terminal repeats are integrated at several sites within this region, one of which is known to enhance susceptibility for Type I diabetes. We examined another LTR within the HLA-region as an additional genetic risk marker. Methods: We investigated the segregation of one long-terminal repeat (DQ-LTR13), located 1.3 kb upstream of HLA DQB1 with different HLA-DQ haplotypes, and its transmission to patients. A total of 284 Caucasian families (203 German and 81 Belgian) with at least one diabetic offspring were genotyped for DQA1, DQB1 and DQ-LTR13. Results: DQ8/LTR13 ⁺ was preferentially transmitted (139 transmitted vs 28 not transmitted; P^TDT = 1.67 × 10^–14) whereas no deviation from expected transmission frequencies was observed for DQ8/LTR13 ^– (20 transmitted vs 17 not transmitted; P^TDT = 1.00). DQ8/LTR13 ⁺ alleles conferred a significantly higher risk for Type I diabetes than DQ8/LTR13 ^– alleles (pχ ² = 2.58 × 10^–14). This difference remained significant even after DRB1 subtyping (pχ ² = 0.02). Also, there was a significant difference when comparing the transmission of DQ2/LTR13 ⁺ and DQ2/LTR13 ^– alleles (pχ ² = 0.01), the latter conferring an increased risk. The transmission of DQ-LTR13 ⁺ haplotypes did not show any differences regarding paternal, maternal or gender-related stratification. However, DQ8/LTR13 ^– was significantly more often transmitted from mothers (pχ ² = 0.01) and to female patients (pχ ² = 0.04). Conclusion/interpretation: We conclude that DQ-LTR13 marks additional genetic risk for Type I diabetes on predisposing DRB1^*0401-DQ8 and DQ2 haplotypes and will help to further define susceptibility in this gene region. [Diabetologia (2002) 45: 443–447] Received: 2 August 2001 and in revised form: 29 October 2001     

Human leukocyte antigen allele associations in type-1 autoimmune hepatitis patients from western India

BACKGROUND AND AIMS: The immunogenetic basis of autoimmune diseases has become more and more evident. We have analyzed the human leukocyte antigen (HLA) associations with type-1 autoimmune hepatitis (AIH) among patients from western India. METHODS: In 20 patients and 120 healthy controls, polymerase chain reaction amplified with sequence specific primers and hybridized with oligoprobes was carried out to elucidate the HLA A, B, C and DRB1 allele associations. RESULTS: The study revealed that A*0222 (20% vs 1.66%; P = 0.0001), A*3201 (15% vs 0.83%; P = 0.0004), A*680102 (30% vs 6.66%; P = 0.001), B*35 (40% vs 11.66%; P = 0.001), B*5501 (10% vs 0.83%; P = 0.008), Cw*0102 (15% vs 1.66%; P = 0.002) and Cw*070101 (50% vs 11.66%; P = 2.5E-05) were significantly increased among the A, B and C alleles of AIH patients. Among the HLA DRB1 alleles, DRB1*0301 (20% vs 6.19%; P = 0.03), DRB1*1301 (15% vs 2.65%; P = 0.01), DRB1*14 (30% vs 11.5%; P = 0.02) and DRB1*1501 (40% vs 22.12%; P = 0.08) were increased in AIH patients when compared with the controls. CONCLUSIONS: The present study indicates that the HLA susceptibility to type 1 AIH in the different populations studied is complex.     

Potential celiac disease in type 1 diabetes: a multicenter study

Aims

To describe the prevalence of potential celiac disease (pot-CD) in young patients with type 1 diabetes mellitus (T1DM) and characterize their clinical features.

Methods

This cross-sectional multicenter study involved 8717 T1DM patients from 31 Italian centers. Information was collected on the total number of T1DM patients, CD patients and pot-CD patients. The following data were collected on pot-CD patients: gender, age at T1DM diagnosis, age at the first CD serological positivity, presence of CD-related symptoms, presence of other autoimmune disorders and treatment with gluten free diet (GFD). One thousand-three-hundred-sixty-one patients who were positive for CD serology were the control group.

Results

CD serological positivity was found in 7.2% T1DM patients. Prevalence of pot-CD was 12.2% (n = 77) among CD positive patients: symptoms were present in 12/77; a third autoimmune disorder was found in 15 patients. Prevalence of pot-CD in the control population was 8.4% (n = 114; p = 0.005). No difference was found with regard to clinical features. Only few symptomatic patients were on GFD both in T1DM and control patients.

Conclusions

A higher prevalence of pot-CD was found in T1DM patients, that may be ascribed to the routine screening, although the influence of genetic factors cannot be excluded.     

The celiac iceberg: from the clinical spectrum to serology and histopathology in children and adolescents with type 1 diabetes mellitus and Down syndrome

Objective: The objective of this study is to investigate the occurrence of gastrointestinal (GI) and extraintestinal symptoms in children and adolescents with type 1 diabetes mellitus (DM1) and Down syndrome (DS) and their association with specific antibodies and histopathology of celiac disease (CelD), representing its clinical forms in the iceberg. Material and methods: Cross-sectional study (November 2009–December 2012) conducted at an outpatient care facility in Northeast Brazil including patients [DM1 (n?=?111); DS (n?=?77)] aged 10 months–18 years old. Measurement of anti-endomysial (EmA) and anti-tissue transglutaminase (anti-tTG) IgA antibodies was performed, as was that of anti-tTG-IgG in the cases with low serum IgA. The patients with antibody positivity were subjected to small intestine biopsy. Results: GI symptoms occurred in 53.7% of the sample, extraintestinal symptoms in 4.3%, and antibody positivity in 28.2% (n?=?53). Of those who underwent biopsy (n?=?40), histopathological findings of CelD were found in 37.5% [DM1?=?5/111 (4.5%), DS?=?10/77 (13.0%)]. GI symptoms were associated with antibody positivity, but not with the histopathology. The GI (32.5%), silent (5.0%), and potential (62.5%) forms of disease were detected. Conclusions: The prevalence of GI symptoms was high in groups DM1 and DS, and the occurrence of such symptoms was associated with antibody positivity. The lack of association between the symptoms and histopatholological findings points to the inconsistency of the former as indicators of CelD. Although the GI form predominated among the cases with active CelD, its contribution to the celiac iceberg was smaller compared with the potential form, which determined the large and submerged base of the iceberg representing the high-risk groups investigated.     

Genetic differences between type 1 diabetes with and without other autoimmune diseases

Background

Clusters of autoimmune diseases (ADs) are present in some people with type 1 diabetes. This clustering suggests the existence of common genetic backgrounds for abnormal autoimmunity in these individuals. However, the genetic differences between type 1 diabetes patients with and without other ADs are not well known.

Methods

To investigate the clinical background and genetic differences between type 1 diabetes patients with and without other ADs, single nucleotide polymorphisms (SNPs) in the CTLA4, SUMO4, PTPN22, IRF5, STAT4, and BLK genes were analysed by using either a TaqMan assay or direct sequencing. The frequencies of alleles, genotypes of each gene, and the human leukocyte antigen (HLA) haplotype were analysed to investigate differences among 3 groups: type 1 diabetes with systemic ADs (group A), type 1 diabetes with other organ‐specific ADs (group B), and type 1 diabetes without other ADs (group C).

Results

The frequency of the C allele in the ‐1123G > C SNP in the PTPN22 gene promoter was significantly higher in groups A and B than in group C (P = .0258 and .0207, respectively). The allele frequencies of the other SNPs were comparable. The frequency of HLA DRB1*0405‐DQB1*0401 was significantly higher in groups A and B than in group C (P = .021 and .0395, respectively).

Conclusions

The ‐1123G > C SNP in the PTPN22 gene promoter and HLA DRB1*0405‐DQB1*0401 might influence the concurrence of systemic and organ‐specific ADs in patients with type 1 diabetes.     

Celiac Disease in an Adult Turkish Population with Type 1 Diabetes Mellitus

Celiac disease is a frequent cause of morbidity among patients with type 1 diabetes mellitus. In this study our objective was to determine the prevalance of celiac diasease in a Turkish adult population with type 1 diabetes mellitus. Patients included 122 type 1 diabetes cases from adult diabetes clinic. Total IgA and IgA-antiendomysial antibody (AEA) assays were performed. Patients positive for IgA-AEA were asked to undergo small intestinal biopsy. Of the 122 patients, none was IgA deficient and 3 had positive IgA-AEA results (2.45%). All three of these patients had biopsies diagnostic of celiac disease. The body mass index (BMI) values of patients with positive AEA were significantly lower than normal (P = 0.024). Among the gastrointestinal complaints there was an association between early satiety and AEA positivity (P = 0.02). None of the other gastrointestinal complaints or age, duration of diabetes, glycosylated hemoglobin values, or insulin doses used were found to be related to AEA positivity. Celiac disease has a high prevalence among Turkish paients with type 1 diabetes mellitus. Screening for IgA-AEA during routine investigations of type 1 diabetic patients is important to prevent celiac-associated symptoms.     

人类白细胞抗原A和DRB1基因与1型糖尿病的相关性研究

目的研究江苏地区人类白细胞抗原（HL4）-A和月出-DRBl基因频率及单倍型与1型糖尿病的相关性。方法于2008至2009年在江苏省江阴市和南京市选择自发酮症急性起病、依赖胰岛素治疗的1型糖尿病门诊或住院患者51例（1型糖尿病组）,其中男27例,女24例,平均发病年龄（14±9）岁。另以2002至2006年登记加入中华骨髓库江苏分库的汉族无关骨髓捐献志愿者HLA分型资料20248份为对照。从受试者外周血中提取细胞基因组DNA,利用聚合酶链反应-寡核苷酸探针序列特异性引物技术进行HLA—A和月似-DRBl基因分型,应用Arlequin软件分析计算单倍型频率及连锁不平衡情况,通过卡方检验等比较组间基因频率、单倍型频率及疾病相关性分析。结果HLA-A点频率最高的为A＊02和A＊24,HLA-DRBl位点频率最高的为DRBl＊09。与对照组相比,1型糖尿病组HLA—A＊3[6．86％（7／102）比2．43％（984／40496）,X^2=8．40,P〈0．01,比值比（OR）=3．00]、A＊24[27．45％（28／102）比16．79％（6799／40496）,X^2=8．27,P〈0．01,OR=1．87]和DRBl＊09[32．35％（33／102）比16．15％（6540／40496）,X^2=19．69,P〈0．01,OR=2．47]、DRBl＊03[15．69％（16／102）比4．76％（1927／40496）,X^2=26．66,P〈0．01,OR=3．69]频率显著升高。A＊01-DRBl＊03在连锁不平衡分析中为1型糖尿病组所特有。结论检测出位点A＊03、A＊24及DR03、DR09对1型糖尿病的易患性,发现3个有易患作用的A—DR单倍型,观察到与1型糖尿病关联的祖先单倍型A01DR03。     

Zonulin as a potential putative biomarker of risk for shared type 1 diabetes and celiac disease autoimmunity

The incidence of type 1 diabetes (T1D) is increasing annually, in addition to other childhood‐onset autoimmune diseases. This review is inspired by recent strides in research defining the pathophysiology of autoimmunity in celiac disease, a disease that has significant genetic overlap with T1D. Population genetic studies have demonstrated an increased proportion of newly diagnosed young children with T1D also have a higher genetic risk of celiac disease, suggesting that shared environmental risk factors are driving the incidence of both diseases. The small intestine barrier forms a tightly regulated interface of the immune system with the outside world and largely controls the mucosal immune response to non‐self‐antigens, dictating the balance between tolerance and immune response. Zonulin is the only known physiological modulator of the intercellular tight junctions, important in antigen trafficking, and therefore, is a key player in regulation of the mucosal immune response. While usually tightly controlled, when the zonulin pathway is dysregulated by changes in microbiome composition and function, antigen trafficking control is lost, leading to loss of mucosal tolerance in genetically susceptible individuals. The tenant of this hypothesis is that loss of tolerance would not occur if the zonulin‐dependent intestinal barrier function is restored, thereby preventing the influence of environmental triggers in individuals genetically susceptible to autoimmunity. This review outlines the current research and a structured hypothesis on how a dysregulated small intestinal epithelial barrier, a “leaky gut,” may be important in the pathogenesis of autoimmunity in certain individuals at risk of both T1D and celiac disease.