Diagnostic immunology in celiac disease

Serum autoantibodies to transglutaminase and endomysium are found in the majority of patients with celiac disease, an autoimmune multisystem disorder affecting approximately 1% of Western and Middle-Eastern populations. Detection of these antibodies plays a crucial role in the diagnosis of celiac disease. The aim of this review is to summarize recent publications in this field, with particular focus on the applications and limitations of celiac autoantibody testing in routine clinical practice.     

消化道疾病患儿血清抗组织谷氨酰胺转移酶抗体阳性病例分析

目的 对消化道疾病住院儿童中的抗组织谷氨酰胺转移酶(tTG)抗体阳性病例进行分析,探索适合我国儿童乳糜泻疾病诊疗的血清学检测.方法 采用ELISA方法检测患儿血清中tTG抗体IgA和IgG,采用间接免疫荧光法检测患儿血清中的抗肌内膜抗体(EMA)和麦胶蛋白抗体(AGA) IgA和IgG.收集所有患儿临床资料,包括小肠黏膜病理分析等.结果 162例患儿中,11例血清IgA-tTG和IgG-AGA阳性.11例中,2例tTG、EMA和AGA全部阳性,3例伴有IgMIgG-EMA和IgA-AGA阳性,1例伴有IgG-EMA可疑阳性、IgA-EMA和IgA-AGA阳性,4伴有IgA-EMA和IgA-AGA阳性,1例伴有IgG-tTG可疑阳性.以上11例IgA-tTG和IgG-AGA阳性患儿十二指肠黏膜都有中重度以上程度损害,8例并发心肌损害、肝功能损害、营养不良、生长发育迟缓等.其中7例临床诊断为乳糜泻、且无麸质饮食试验治疗有效.结论 11例IgA-tTG阳性患儿3种血清抗体检测结果与十二指肠黏膜病理活检相符.血清抗体,特别是tTG检测可以更快更早地帮助临床诊断乳糜泻.     

Celiac disease‐associated antibodies in patients with psoriasis and correlation with HLA Cw6

Etiopathology of psoriasis is not completely understood. Patients with psoriasis show elevated sensitivity to gluten. The aim of this study was to see the expression of celiac disease (CD)‐associated antibodies gliadin IgA, gliadin IgG, and tissue transglutaminase IgA, and their correlation with HLA Cw6 in patients with psoriasis. The study comprised 56 patients with psoriasis and 60 healthy controls (HC). The levels of antibodies were detected by using ELISA technique and HLA Cw6 typing was carried out by microcytotoxicity method. HLA Cw6 was significantly expressed in psoriasis cases when compared with HC (P<0.05). CD‐associated antibodies gliadin IgA/IgG and tissue transglutaminase IgA were significantly higher in the serum of patient with psoriasis when compared with HC (P<0.05, <0.05, and 0.01, respectively). Serum anti tissue transglutaminase IgA (anti tTG IgA) was significantly higher in females when compared with males and expressed more in elderly patients. There was a significant positive correlation among the antibodies (anti gliadin IgA with anti gliadin IgG: r=0.67, P<0.05; anti gliadin IgA with anti tTG IgA: r=0.45, P<0.05, anti gliadin IgG with anti tTG IgA: r=0.26, P<0.05, respectively), whereas insignificant with HLA Cw6. Our study concludes that latent CD or CD‐associated antibodies were present in patients with psoriasis and also concludes that HLA Cw6 has no association with expression of these antibodies in patients with psoriasis. J. Clin. Lab. Anal. 24:269–272, 2010. © 2010 Wiley‐Liss, Inc.     

Immunological indicators of coeliac disease activity are not altered by long‐term oats challenge

Coeliac disease is a gluten‐sensitive enteropathy that develops in genetically susceptible individuals. The disease exhibits many features of an autoimmune disorder. These include the production of highly specific anti‐endomysial autoantibodies directed against the enzyme tissue transglutaminase. It is well accepted that wheat‐, barley‐ and rye‐based foods should be excluded in the gluten‐free diet. Although several studies report that oats ingestion is safe in this diet, the potential toxicity of oats remains controversial. In the current study, 46 coeliac patients ingested oats for 1 year and were investigated for a potential immunogenic or toxic effect. Stringent clinical monitoring of these patients was performed and none experienced adverse effects, despite ingestion of a mean of 286 g of oats each week. Routine histological analysis of intestinal biopsies showed improvement or no change in 95% of the samples examined. Furthermore, tissue transglutaminase expression in biopsy samples, determined quantitatively using the IN Cell Analyzer, was unchanged. Employing immunohistochemistry, oats ingestion was not associated with changes in intraepithelial lymphocyte numbers or with enterocyte proliferation as assessed by Ki‐67 staining. Finally, despite the potential for tissue transglutaminase to interact with oats, neither endomysial nor tissue transglutaminase antibodies were generated in any of the patients throughout the study. To conclude, this study reaffirms the lack of oats immunogenicity and toxicity to coeliac patients. It also suggests that the antigenic stimulus caused by wheat exposure differs fundamentally from that caused by oats.     

Inhibitory Effect of Tissue Transglutaminase （tTG） Antisense Oligodeoxynucleotides on tTG Expression in Cultured Bovine Trabecular Meshwork Cells

To study the effect of tTG fully phosphorothioated antisense oligodeoxynucleotides （tTG-ASDON） on tTG expression in cultured bovine trabecular meshwork cells （BTMCs） in vitro and explore a new treatment alternative for primary open angle glaucoma （POAG）, the ASDON1 and ASDON2 complementary to the protein codogram region of tTG were designed, synthesized and phosphorothioated according to the secondary structure of tTG. The ASDON1 and ASDON2 were embedded in Lipofectamine and transfected into BTMCs. The untreated group served as negative controls. The expression of tTG in the mRNA and protein level were measured by semi-quantitative RT-PCR and immunohistochemical technique-Supervision method respectively. Our results showed that both the mRNA and the protein of tTG with tTG-ASDON1 and tTCr-ASDON2 were significantly decreased as compared with that of the controls （P〈0.05）. On the other hand, no significant difference was found between the ASDON1 group and the ASDON2 group. It is concluded that the expression of tTG mRNA and protein in cultured BTMC are down-regulated by tTG- ASDON. As a result, tTG-ASDON may be used for the treatment of POAG through the inhibitory effect on the expression of tTG.     

PINK1 phosphorylates transglutaminase 2 and blocks its proteasomal degradation

Parkinson's disease (PD) is characterized by progressive dopaminergic neuronal loss and the formation of abnormal protein aggregates, referred to as Lewy bodies (LBs). PINK1 is a serine/threonine protein kinase that protects cells from stress‐induced mitochondrial dysfunction. PINK1 gene mutations cause one form of autosomal recessive early‐onset PD. Transglutaminase 2 (TG2) is an intracellular protein cross‐linking enzyme that has an important role in LB formation during PD pathogenesis. This study identifies PINK1 as a novel TG2 binding partner and shows that PINK1 stabilizes the half‐life of TG2 via inhibition of TG2 ubiquitination and subsequent proteasomal degradation. PINK1 affects TG2 stability in a kinase‐dependent manner. In addition, PINK1 directly phosphorylates TG2 in carbonyl cyanide m‐chlorophenyl hydrazine‐induced mitochondrial damaged states, thereby enhancing TG2 accumulation and intracellular protein cross‐linking products. This study further confirms the functional link between upstream PINK1 and downstream TG2 in Drosophila melanogaster. These data suggest that PINK1 positively regulates TG2 activity, which may be closely associated with aggresome formation in neuronal cells. © 2014 Wiley Periodicals, Inc.     

New insights in the pathogenesis of immunoglobulin A vasculitis (Henoch-Schönlein purpura)

Immunoglobulin A vasculitis (IgAV), also referred to as Henoch-Schönlein purpura, is the most common form of childhood vasculitis. The pathogenesis of IgAV is still largely unknown. The disease is characterized by IgA1-immune deposits, complement factors and neutrophil infiltration, which is accompanied with vascular inflammation. Incidence of IgAV is twice as high during fall and winter, suggesting an environmental trigger associated to climate. Symptoms can resolve without intervention, but some patients develop glomerulonephritis with features similar to IgA nephropathy that include hematuria, proteinuria and IgA deposition in the glomerulus. Ultimately, this can lead to end-stage renal disease. In IgA nephropathy immune complexes containing galactose-deficient (Gd-)IgA1 are found and thought to play a role in pathogenesis. Although Gd-IgA1 complexes are also present in patients with IgAV with nephritis, their role in IgAV is disputed. Alternatively, it has been proposed that in IgAV IgA1 antibodies are generated against endothelial cells. We anticipate that such IgA complexes can activate neutrophils via the IgA Fc receptor FcαRI (CD89), thereby inducing neutrophil migration and activation, which ultimately causes tissue damage in IgAV. In this Review, we discuss the putative role of IgA, IgA receptors, neutrophils and other factors such as infections, genetics and the complement system in the pathogenesis of IgA vasculitis.     

Serum cytokine pattern in young children with screening detected coeliac disease

Coeliac disease is an autoimmune disease characterized by inflammation localized to the small bowel, but less is known about systemic signs of inflammation. The aim was to measure cytokines of the T helper 1 (Th1) and T helper 2 (Th2) cell patterns in children with screening‐detected coeliac disease before and after treatment with a gluten‐free diet. Serum samples selected before and after the start of a gluten‐free diet from 26 3‐year‐old children diagnosed with biopsy‐proven coeliac disease and from 52 matched controls were assayed in an multiplex enzyme‐linked immunosorbent assay (ELISA) for the 10 cytokines: interferon (IFN)‐γ, interleukin (IL)‐1β, IL‐2, IL‐4, IL‐5, IL‐8, IL‐10, IL‐12p70, IL‐13 and tumour necrosis factor (TNF)‐α. Among Th1 cytokines, IFN‐γ and IL‐12p70 were elevated significantly in children with coeliac disease compared to controls (P < 0·001 and P = 0·001, respectively). Similar findings were demonstrated for the Th2 cytokines IL‐5 (P < 0·001), IL‐10 (P = 0·001) and IL‐13 (P = 0·002). No difference in cytokine levels between the two groups was found for TNF‐α, IL‐1β, IL‐2, IL‐4 and IL‐8. After gluten‐free diet, levels of IL‐5, IL‐12 and IL‐10 decreased significantly (P < 0·001, P = 0·002 and P = 0·007) and IFN‐γ levels were reduced (P = 0·059). Young children with coeliac disease detected by screening demonstrate elevated levels of serum cytokines at time of diagnosis. A prolonged systemic inflammation may, in turn, contribute to long‐term complications known to be associated with untreated coeliac disease.     

Development of celiac disease-associated antibodies in offspring of parents with Type I diabetes

Aims/hypothesis. The aim of this study was to determine the frequency and temporal development of antibodies related to celiac disease in offspring of parents with Type I (insulin-dependent) diabetes mellitus. Methods. Sera from 913 offspring of parents with Type I diabetes prospectively followed from birth to the age of 8 years were tested for IgG-transglutaminase antibodies (IgG-tTGCAs), endomysial IgA antibodies (EMA) and gliadin antibodies. Results. We found tTGCAs in 32 (3.5 %) of the 913 relatives. Prevalence was related to age and reached 6.5 % at age 8 years. Endomysial IgA antibodies were detected in 44 % of the relatives with tTGCAs and 0.6 % of tTGCA negative relatives and were also most prevalent (5 %) in those aged 8 years. Both tTGCAs and EMAs were more frequent in relatives with the HLA DRB1^*03 DQA1*0501 DQB1^*02 haplotype (7.1 % and 7.2 %, respectively; p < 0.005). Anti-gliadin antibodies were common in both tTGCA positive (42 %) and negative (23 %) relatives, did not show a relation with age and were less prevalent in relatives with HLA DR3 (p < 0.05). There was no association between the presence of antibodies associated with celiac disease and islet autoantibodies in these relatives. Of the relatives 15 (1.6 %) had tTGCAs plus EMAs. In two of these, anti-gliadin antibodies were detected before the detection of tTGCAs and EMAs at the age of 9 months whereas none of the remainder had any antibodies associated with celiac disease before age 2 years. In three there were no detectable anti-gliadin antibodies in any of the samples tested. Celiac disease without clinical symptoms was diagnosed in 9 of 12 by intestinal biopsy. Conclusion/interpretation. A statistically significant proportion of relatives of patients with Type I diabetes have celiac disease-associated autoimmunity and the silent form of celiac disease early in life. These relatives should, therefore, be considered for celiac antibody screening. [Diabetologia (2000) 43: 1005–1011] Received: 20 January 2000 and in revised form: 26 April 2000