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Characterization of the humoral immune response to glutamic acid decarboxylase in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) and/or type 1 diabetes.

OBJECTIVE: A humoral autoimmune response to glutamic acid decarboxylase (GAD65) is common both in patients with type 1 diabetes and in those with the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome, while overt type 1 diabetes is relatively rarely diagnosed in APECED patients. The aim of this study was to assess whether this difference in the incidence of type 1 diabetes is associated with variability in the humoral immune response to GAD65, one of the major autoantigens in type 1 diabetes. METHODS: Epitope- and isotype-specific GAD65 autoantibodies were analysed in 20 patients with APECED and 20 patients with newly diagnosed type 1 diabetes alone by radiobinding assays. RESULTS: GAD65 autoantibodies targeted the middle and carboxy-terminal regions of GAD65 and occasionally the amino-terminal region in the APECED patients and comprised mainly the IgG1 subclass and less frequently the IgG2 and IgG4 subclasses. The profile of epitope- and isotype-specific GAD65 autoantibodies was similar in type 1 diabetes and APECED, except that IgG2 subclass antibodies were observed more often and at higher levels in the patients with type 1 diabetes alone (P < 0.05). None of the measured parameters separated APECED patients with type 1 diabetes from those without type 1 diabetes. CONCLUSION: APECED-associated humoral autoimmunity to GAD65 does not differ markedly from that observed in type 1 diabetes; only IgG2-GAD65 antibodies may be more closely associated with the latter entity.

Adult↗

Chronic bilateral keratitis in autoimmune polyendocrinopathy-candidiadis-ectodermal dystrophy (APECED). A long-term follow-up and visual prognosis.

PURPOSE: To report the outcome of chronic bilateral keratitis and other ocular manifestations in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). MATERIAL AND METHODS: The material consists of 69 patients with APECED, who were examined by the senior author as referrals from the pediatricians. The patients were seen at the Helsinki University Eye Hospital a total of 370 times and the follow-up periods range from 2 to 25 years. RESULTS: 25% of the patients had chronic bilateral keratitis with symptoms of intense photophobia, blepharospasm and lacrimation. On 13 patients the first symptoms appeared before the age of 4 years. Keratitis was the first presenting sign before any evidence of systemic disease in three patients, and in all patients keratitis was among the first three manifestations of the syndrome. The clinical picture from the acute to the chronic cicatricial stage is described. The best corrected visual acuity at the end of the follow-up was 0.6 or better in six patients only. Of the total material 12 patients had lenticular opacities as the manifestation of hypoparathyroidism. CONCLUSIONS: Chronic bilateral keratitis is an ocular manifestation of APECED and in its etiology both hypoparathyroidism and candidiasis may be ruled out as single causes. When an ophthalmologist is confronted with a young child with bilateral chronic keratitis with symptoms of intense photophobia, blepharospasm, lacrimation and either with mucocutaneous candidiasis or hypoparathyroidism, the patient should be referred to a pediatric endocrinological consultation for the possibility of underlying APECED.

Age of Onset↗

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome with renal failure: impact of posttransplant immunosuppression on disease activity.

CONTEXT: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive disorder caused by mutations in the gene AIRE (autoimmune regulator). APECED affects mainly endocrine organs resulting in hypoparathyroidism, adrenocortical failure, diabetes mellitus, hypogonadism, and hypothyroidism. Nonendocrine organ manifestations are autoimmune hepatitis, vitiligo, pernicious anemia, exocrine pancreatic insufficiency, and alopecia. APECED's first manifestation generally is mucocutaneous candidiasis presumably related to T cell dysfunction. PATIENT: A 5-yr-old Iranian girl presented first with pernicious anemia, exocrine pancreatic insufficiency, and nail candidiasis. She had renal dysfunction due to chronic interstitial nephritis (CIN), which progressed to end-stage renal failure. She was transplanted 1 yr later. Common causes of CIN were excluded. APECED was suspected first because she developed progressively hypoparathyroidism, adrenocortical failure, glucose intolerance, and hypothyroidism. RESULTS: Genetic analysis revealed a large homozygous deletion (g.424_2157del1734), spanning exons 2-4, in the AIRE gene. The predicted protein, if it is produced, has only 44 amino acids (exon 1) in common with the wild-type protein. Immunosuppression after the first renal transplant included prednisone, azathioprine, and cyclosporine A. Multiple acute rejection episodes occurred. Chronic rejection resulted in lost graft and she was retransplanted 2 yr later. Surprisingly, all APECED-related symptoms including candidiasis and autoantibody levels decreased, presumably due to the reinforced immunosuppression (tacrolimus, mycophenolate mofetil, prednisone). CONCLUSIONS: This is the first report of an APECED patient with CIN resulting in end-stage renal failure. Clinical and biological improvement was observed under posttransplant multidrug immunosuppression including tacrolimus and mycophenolate mofetil.

Anti-Inflammatory Agents↗

Severe malabsorption in autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy syndrome successfully treated with immunosuppression.

A 15 year old boy with autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy syndrome suffered recurrent episodes of severe intractable diarrhoea, steatorrhoea, and hypocalcaemia. The only treatment modality, which controlled the malabsorption syndrome, was immunosuppression with intravenous high dose methylprednisolone and oral methotrexate maintenance therapy.

Adolescent↗

Organ-specific and non-organ-specific autoantibodies in children and young adults with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED).

OBJECTIVE: The aim of the study was to assess the complex of autoantibodies which can be detected in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a rare autosomal recessive disease in which the extent of autoimmunity is still unknown. DESIGN: Antibodies (A) to parathyroid glands, adrenal cortex (AC-A), ovary and testis (steroid cell antibodies, SC-A), pancreatic islet cells (IC-A), gastric parietal cells, and non-organ-specific antigens were investigated in 11 APECED patients living in the Salento region of southern Italy. Further measurements included antibodies to cytochrome P450 (CYP) enzymes: cholesterol side-chain cleavage enzyme (CYP11A), 21-hydroxylase (CYP21) and 17alpha-hydroxylase (CYP17); and to glutamic acid decarboxylase 65-kDa isoform (GAD65), tyrosine phosphatase-like protein IA2, thyroglobulin (TG), thyroperoxidase (TPO), thyrotropin receptor, liver CYP enzymes and intrinsic factor. METHODS: Antibodies to organs and subcellular fractions were detected by immunofluorescence. Radiobinding, immunoradiometric, and immunoblotting assays were used for the other measurements. RESULTS: AC-A and SC-A were positive in all sera; among antibodies to adrenal CYP enzymes, only CYP21-A were present in all the patients with Addison's disease of short-medium duration (<15 years). Of three patients with Addison's disease of long duration (>15 years), two tested positive for antibodies to all three CYP enzymes, and the other for only CYP11A-A. In all sera CYP11A-A and/or CYP17-A were found. Two patients tested positive for both IC-A and GAD65-A, one for both IC-A and IA2-A, and one for GAD65-A; the fasting C-peptide assay showed no statistical difference between these four subjects and the others. All four hypothyroid patients were positive for TPO-A, while two of them were positive and two were negative for TG-A; two euthyroid subjects had positivity for TG-A. Liver-kidney microsomal antibodies reacting against the CYP2A6 were detected in two patients with autoimmune hepatitis. All but one sera contained anti-nuclear antibodies at a titre ranging between 1:20 and 1:80; however, only two patients had a connective tissue disease (Sjögren's syndrome). CONCLUSIONS: Several autoantibodies may be detected in any APECED patient. Our data confirm that CYP21-A and TPO-A are major autoantibodies involved in APECED-associated Addison's disease and hypothyroidism respectively, while CYP11A-A and CYP17-A correlate with positivity for SC-A. Markers of islet cell autoimmunity are frequent, but prevalence and modalities of progression to overt beta-cell failure have to be clarified. Low-titre non-organ-specific autoantibodies are a feature of autoimmunity in APECED, but their role has yet to be fully explained.

Adolescent↗

Characterization of a novel gene, C21orf2, on human chromosome 21q22.3 and its exclusion as the APECED gene by mutation analysis.

Exon trapping was performed from a partial cosmid, PAC, and P1 clone contig from human chromosome 21 between MX1 and 21qter to identify genes that may be involved in the pathogenesis of Down syndrome or several of the genetic diseases that map to chromosome 21q22.3. One 19-bp exon showed identity to three ESTs. The complete sequence of the EST clones, RT-PCR, and cDNA library screening were used to determine the full-length cDNA sequence of 2.2 kb with an open reading frame of 256-amino-acids. The putative 256-amino-acid peptide has homology with a hypothetical Caehorhabditis elegans protein of unknown function. Northern blot analysis of this gene, termed C21orf2 (chromosome 21 open reading frame 2), revealed two ubiquitously expressed mRNAs of 2.2 and 1.2 kb produced by use of alternative polyadenylation sites. Hybridization of the EST clones to a cosmid contig in chromosome 21q22.3 mapped C21orf2 just distal to PFKL, a critical mapping region for several genetic diseases. Comparison to publicly available genomic sequence, and additional data, revealed that the gene is split into seven exons over 10.5 kb, further refining the mapping position to only 1.2 kb distal to PFKL with the direction of transcription toward the centromere. The 5'UTR is contiguous with D21S400, and intron 2 contains a 52-bp VNTR polymorphism. Given its mapping position, C21orf2 is a candidate for involvement in disorders including autoimmune polyglandular disease type I (also called autoimmune polyendocrinopathy candidiasis ectodermal dystrophy or APECED) and the autosomal nonsyndromic deafness loci, DFNB8 and DFNB10. Mutation analysis using sequencing of RT-PCR and genomic DNA-derived PCR products, SSCP, and Southern and Northern blot analyses in APECED patients excluded C21orf2 as the gene for APECED.

Amino Acid Sequence↗

Expression profiling of autoimmune regulator AIRE mRNA in a comprehensive set of human normal and neoplastic tissues.

Defects in the autoimmune regulator (AIRE) gene cause the monogenic autoimmune disease autoimmune polyendocrinopathy syndrome type 1 (APS-1), which is characterized by a loss of self-tolerance to multiple organs. In concordance with its role in immune tolerance, AIRE is strongly expressed in medullary thymic epithelial cells (mTECs). Data on mechanisms controlling AIRE activation and the expression of this gene in other tissues are fragmentary and controversial. We report here AIRE mRNA expression profiling of a large set of normal human tissues and cells, tumor specimen and methylation deficient cell lines. On this broad data basis we found that AIRE mRNA expression is confined to mTECs in thymus and to lymph node tissue and that DNA hypomethylation contributes to transcriptional control of this gene.

Cell Line, Tumor↗

Human disorders of ubiquitination and proteasomal degradation.

PURPOSE OF REVIEW: The goal of this review is to provide an overview of rapidly evolving information on a new group of genetic inborn errors affecting ubiquitination and proteasomal degradation of proteins and to suggest a classification scheme for these disorders. The relevant genes encode ubiquitin, ubiquitin enzymes (E1 and many E2s and E3s), deubiquitinating enzymes, proteasomal subunits, and substrates undergoing ubiquitination. RECENT FINDINGS: Since the initial recognition that Angelman syndrome is caused by maternal deficiency of the E6-AP ubiquitin E3 ligase (gene symbol UBE3A), several. other disorders of E3 ligases have been identified, including autosomal recessive juvenile Parkinson disease, the APECED form of autoimmune polyendocrinopathy syndrome, von Hippel-Lindau syndrome, and congenital polycythemia. Disorders that disturb ubiquitin regulatory signaling include at least two subtypes of Fanconi anemia, the BRCA1 and BRCA2 forms of breast and ovarian cancer susceptibility, incontinentia pigmenti, and cylindromatosis. Many disorders affect ubiquitin pathways secondarily. SUMMARY: The authors propose both a genetic and a functional classification for disorders of ubiquitination and proteasomal degradation, as follows. Genetic classes include mutations in (1) the UBB ubiquitin gene; (2) enzymes of ubiquitination including E1, E2, E3, and related proteins; (3) deubiquitinases; (4) proteasomal subunits; and (5) substrates of ubiquitination. Functional classes include defects in (1) proteolytic degradation, (2) ubiquitin signaling, and (3) subcellular localization of substrates. Additional functional classes are likely to be defined, and individual disorders may involve multiple functional defects.

Alzheimer Disease↗

Median eminence dopaminergic nerve terminals: a novel target in autoimmune polyendocrine syndrome?

CONTEXT: Autoantibodies to adenohypophyseal endocrine cells or to vasopressin neurohypophyseal neurons have long been known. Conversely, autoimmune targeting of further hypothalamic-hypophyseal structures, such as the blood-brain barrier-deprived median eminence, has been little studied. OBJECTIVE AND METHODS: We studied a case of autoimmune polyendocrine syndrome type I with GH secretory deficiency, a distinctly rare event in autoimmune polyendocrine syndrome type I. We used rat and bovine tissue substrates to study autoantibodies against hypothalamic-hypophyseal nerve structures and endocrine cells. RESULTS: In the study case, circulating autoantibodies selectively decorated median eminence dopaminergic nerve terminals, as well as pituitary gonadotropes, but not GHRH nerve terminals or pituitary somatotropes. Such autoantibodies appeared de novo in parallel with the onset of GH secretory deficiency, whereas no median eminence labeling was found in patients suffering of idiopathic GH deficiency (n = 7) or in healthy controls (n = 23). CONCLUSIONS: The pathophysiological significance of our patient's autoantibodies remains to be confirmed. Nonetheless, the heterogeneous neuroendocrine structures of the median eminence are pointed out as potential immune targets, relevant to autoimmune polyendocrinopathy, as well as to a wide range of other conditions.

Adolescent↗

Chromosomal localization and complete genomic sequence of the murine autoimmune regulator gene (Aire).

We have recently cloned the murine autoimmune regulator (Aire) gene, the homologue of human AIRE responsible for the autoimmune polyglandular syndrome type 1 (APS1) or autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED). Here, we report the genomic sequence (18,413 bp) for the entire Aire gene and its 5' flanking region, which contains putative regulatory sequences. Comparison of the genomic and cDNA sequences indicates that the Aire gene is composed of 14 exons and the coding sequence shares high similarities between mouse and human. The sizes of the homologous introns in the two species are conserved; however, the introns do not share significant sequence homologies except the sequences near the splice donor and acceptor sites. Sequence analyses of the 5' regulatory region and the complete coding region in three mouse strains (B6, NOD and SJL) did not reveal any sequence variation, suggesting sequence conservation between different inbred mouse strains. Using one of the six microsatellite markers identified by genomic sequencing and a B6 x Cast backcross mapping panel, we mapped the mouse Aire gene to chromosome 10, a syntenic region containing the Cdl18 and Pfkl genes on human chromosome 21q22.

Animals↗

The mouse Aire gene: comparative genomic sequencing, gene organization, and expression.

Mutations in the human AIRE gene (hAIRE) result in the development of an autoimmune disease named APECED (autoimmune polyendocrinopathy candidiasis ectodermal dystrophy; OMIM 240300). Previously, we have cloned hAIRE and shown that it codes for a putative transcription-associated factor. Here we report the cloning and characterization of Aire, the murine ortholog of hAIRE. Comparative genomic sequencing revealed that the structure of the AIRE gene is highly conserved between human and mouse. The conceptual proteins share 73% homology and feature the same typical functional domains in both species. RT-PCR analysis detected three splice variant isoforms in various mouse tissues, and interestingly one isoform was conserved in human, suggesting potential biological relevance of this product. In situ hybridization on mouse and human histological sections showed that AIRE expression pattern was mainly restricted to a few cells in the thymus, calling for a tissue-specific function of the gene product.

Amino Acid Sequence↗

Oral findings in the autoimmune polyendocrinopathy-candidosis syndrome (APECS) and other forms of hypoparathyroidism.

Of twenty-eight patients aged 4 to 28 years with the autoimmune polyendocrinopathy-candidosis syndrome (APECS), twenty-seven had chronic oral candidosis, twenty-five had HPT, twenty-three had enamel hypoplasia, and nineteen had hypoadrenocorticism. Of three patients with other forms of hypoparathyroidism, none had any associated disease or oral abnormality. In nineteen cases candidosis was the first manifestation of APECS. Its occurrence was independent of the other components of the syndrome. The occurrence of enamel hypoplasia also was independent of HPT. Possibly, the enamel organ was affected by an autoimmune episode. No delayed maturation, resorption, or root hypoplasia was observed. Tooth impaction occurred in three patients.

Adolescent↗

Clinical variation of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) in a series of 68 patients.

To define the clinical picture and course of the autosomal recessive disease called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), we report data from our 10-month to 31-year follow-up of 68 patients from 54 families, now 10 months to 53 years of age. The clinical manifestations varied greatly and included from one to eight disease components, 63 percent of the patients having three to five of them. The initial manifestation was oral candidiasis in 41 patients (60 percent), intestinal malabsorption in 6 (9 percent), and keratopathy in 2 (3 percent). All the patients had candidiasis at some time. The earliest endocrine component appeared at 19 months to 35 years of age. Hypoparathyroidism was present in 54 patients (79 percent), adrenocortical failure in 49 (72 percent), and gonadal failure in 15 (60 percent) of the female patients greater than or equal to 13 years of age and 4 (14 percent) of the male patients greater than or equal to 16 years of age. There were multiple endocrine deficiencies in half the patients. From 4 to 29 percent of the patients had periodic malabsorption, gastric parietal-cell atrophy, hepatitis, alopecia, vitiligo, or a combination of these conditions. Dental-enamel hypoplasia and keratopathy were also frequent but were not attributable to hypoparathyroidism. In the patients whose initial manifestation (other than candidiasis) was adrenal failure, the other components developed less often than in the remaining patients. We conclude that the clinical spectrum in patients with APECED is broad. The majority of patients have three to five manifestations, some of which may not appear until the fifth decade. Therefore, all patients need lifelong follow-up for the detection of new components of the disease.

Adolescent↗

Ketoconazole is effective against the chronic mucocutaneous candidosis of autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy (APECED).

Ketoconazole was administered as a single daily oral dose of 200 mg to 12 patients with chronic mucocutaneous candidosis (CMC) of autoimmune polyendocrinopathy-candidosis-ectodermal dystrophy (APECED). The study was double-blind and placebo-controlled, with 4-month therapy periods and crossover, and transfer to open-label ketoconazole therapy in cases of failure. During the double-blind trial, all six initially ketoconazole-treated patients showed a clear clinical and mycological improvement. In contrast there was no change or worsening in the initially placebo-treated group (p = 0.001). Oral candidosis cleared up in all patients, but more rapidly (less than 2 weeks) in those aged less than 25 years than in older patients (4-10 weeks; p = 0.001). Similarly, nail candidosis improved more rapidly in the younger group. All patients had a recurrence of the candidosis during 36-48 months of post-therapy follow-up. The recurrences likewise responded to ketoconazole. In one patient serum transaminase activities were transiently and marginally elevated during 2-6 weeks of therapy.

Adolescent↗

Aire regulates negative selection of organ-specific T cells.

Autoimmune polyendocrinopathy syndrome type 1 is a recessive Mendelian disorder resulting from mutations in a novel gene, AIRE, and is characterized by a spectrum of organ-specific autoimmune diseases. It is not known what tolerance mechanisms are defective as a result of AIRE mutation. By tracing the fate of autoreactive CD4+ T cells with high affinity for a pancreatic antigen in transgenic mice with an Aire mutation, we show here that Aire deficiency causes almost complete failure to delete the organ-specific cells in the thymus. These results indicate that autoimmune polyendocrinopathy syndrome 1 is caused by failure of a specialized mechanism for deleting forbidden T cell clones, establishing a central role for this tolerance mechanism.

Animals↗

Autoimmunity to glutamic acid decarboxylase in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED).

Antibodies to glutamic acid decarboxylase (GAD) occur frequently in patients with APECED, although clinical insulin-dependent diabetes mellitus (IDDM) is seen only in a subgroup of the patients. We studied the cellular immunity to GAD, antibodies to GAD and their association with the HLA DQB1 risk alleles for IDDM in patients with APECED. Proliferation responses to GAD were enhanced in the patients with APECED when compared with the control subjects (P = 0.004), but autoimmunity to GAD was not associated with IDDM in APECED. The levels of interferon-gamma (IFN-gamma) secreted by GAD-stimulated T cells were higher in the patients than in control subjects (P = 0. 001). A negative correlation (r = - 0.436, P = 0.03) existed between the antibody levels and the stimulation indices (SIs) to GAD. In 14 non-diabetic patients no difference in insulin secretion was observed in intravenous glucose tolerance test (IVGTT) between the patients with and without T cell reactivity to GAD. We conclude that cellular immunity to GAD detected as T cell proliferation response to GAD or IFN-gamma secretion by GAD-stimulated T cells was frequent in patients with APECED (69%) and was not restricted to the patients with clinically detectable beta-cell damage.

Adolescent↗

Virus-induced diabetes mellitus. XX. Polyendocrinopathy and autoimmunity.

Mice infected with reovirus type 1 developed transient diabetes and a runting syndrome. The diabetes was characterized by hyperglycemia, abnormal glucose tolerance tests, and hypoinsulinemia. Inflammatory cells and viral antigens were found in the islets of Langerhans, and virus particles were seen in alpha, beta, and delta cells. The runting syndrome consisted of retarded growth, oily hair, alopecia, and steatorrhea. Inflammatory cells and viral antigens were found in the anterior, but not posterior pituitary. Electron microscopy revealed virus particles in growth hormone (GH)-producing cells and radioimmunoassay showed that the concentration of GH in the blood was decreased. Examination of sera from infected mice revealed autoantibodies that, by immunofluorescence, reacted with cytoplasmic antigens in the islets of Langerhans, anterior pituitary, and gastric mucosa of uninfected mice. Absorption studies and enzyme-linked immunosorbent assays designed to identify the reactive antigens showed that some of the autoantibodies were directed against insulin and others against GH. Reovirus type 3, in contrast to reovirus type 1, did not induce autoantibodies to GH. By use of recombinant viruses, the segment of the reovirus genome responsible for the induction of autoantibodies to GH was identified. Virus containing the S1 gene segment from reovirus type 1, which codes for the sigma 1 polypeptide (i.e., hemagglutinin), infected cells in the anterior pituitary and induced autoantibodies to GH, whereas virus containing the S1 gene segment from reovirus type 3 failed to infect cells in the anterior pituitary and did not induce autoantibodies to GH. We conclude that reovirus type 1 infection can lead to polyendocrinopathy and autoimmunity and that the S1 gene segment is required for the induction of autoantibodies to GH.

Animals↗

Monogenic autoimmune diseases - lessons of self-tolerance.

The molecular defects recently identified in the rare monogenic autoimmune diseases (AIDs) have pinpointed critical steps in the pathways that contribute to the development of normal immune responses and self-tolerance. Recent studies of autoimmune polyendocrinopathy syndrome type 1, autoimmune lymphoproliferative syndrome, immunodysregulation, polyendocrinopathy and enteropathy, X-linked, IL-2 receptor alpha-chain deficiency, and, in particular, their corresponding mouse models, have revealed the details of the molecular mechanisms of normal immune tolerance, and exposed how defects in these mechanisms result in human autoimmunity. In addition to a deeper understanding of the immune system, detailed molecular characterization of monogenic AIDs will help us to understand the mechanisms behind common polygenic AIDs and, furthermore, to develop novel therapies and intervention strategies to treat them.

Animals↗