| 1. |
- Bratland, Eirik, et al.
(författare)
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Autoantibodies against aromatic amino acid hydroxylases in patients with autoimmune polyendocrine syndrome type 1 target multiple antigenic determinants and reveal regulatory regions crucial for enzymatic activity
- 2013
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Ingår i: Immunobiology. - : Elsevier BV. - 0171-2985 .- 1878-3279. ; 218:6, s. 899-909
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Tidskriftsartikel (refereegranskat)abstract
- Patients with autoimmune polyendocrine syndrome type 1 (APS-1) frequently have autoantibodies directed against the aromatic amino acid hydroxylases tryptophan hydroxylase (TPH) and tyrosine hydroxylase (TH). We aimed to characterize these autoantibodies with regard to their antigenic determinants, their influence on enzymatic activity and their clinical associations. In particular, we wanted to compare autoantibodies against the two different isoforms of TPH, which display different tissue distribution. Using sera from 48 Scandinavian APS-1 patients we identified 36 patients (75%) with antibodies against one or more of these three enzymes. Antibodies against TPH1, but not TPH2, were associated with malabsorption in the whole Scandinavian cohort, while TH antibodies were associated with dental enamel hypoplasia in Norwegian patients. Subsequent experiments with selected patient sera indicated that while the C-terminal domain was the immunodominant part of TPH1, the epitopes of TPH2 and TH were mainly located in the N-terminal regulatory domains. We also identified a TPH1 specific epitope involved in antibody mediated inhibition of enzyme activity, a finding that provides new insight into the enzymatic mechanisms of the aromatic amino acid hydroxylases and knowledge about structural determinants of enzyme autoantigens. In conclusion, TPH1,TPH2 and TH all have unique antigenic properties in spite of their structural similarity.
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| 2. |
- Bratland, Eirik, et al.
(författare)
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Epitope mapping of human aromatic L-amino acid decarboxylase
- 2007
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 353:3, s. 692-698
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Tidskriftsartikel (refereegranskat)abstract
- Autoimmune polyendocrine syndrome type I (APS I) is a rare hereditary condition considered a model disease for organ specific autoimmunity. A wide range of autoantibodies targeting antigens present in the affected organs have been identified. Autoantibodies against aromatic l-amino acid decarboxylase (AADC) are present in about 50% of APS I patients. In order to increase our understanding of autoantibody specificity in APS I, the aim of the present study was to localize target regions on AADC recognized by sera from APS I patients. Using several complementing strategies, we have shown that autoantibodies against AADC mainly recognize conformational epitopes. The major antigenic determinants were detected N-terminally to amino acid residue 237. Replacement of amino acids 227–230 (ERDK) with alanine residues reduced the reactivity towards AADC by >80% in all patient sera tested, suggesting that amino acids 227–230 are an important part of an immunodominant epitope.
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| 3. |
- Lima, Kari, et al.
(författare)
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Hypoparathyroidism and autoimmunity in the 22q11.2 deletion syndrome
- 2011
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Ingår i: European Journal of Endocrinology. - 0804-4643 .- 1479-683X. ; 165:2, s. 345-352
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To characterize the endocrine and autoimmune disturbances with emphasis on parathyroid dysfunction in patients with 22q11.2 deletion syndrome (22q11.2 DS). Design: In this nationwide survey; 59 patients (age 1-54 years) out of 86 invited with a 22q11.2 DS were recruited through all the genetic institutes in Norway. Methods: Data was collected from blood tests, medical records, a physical examination and a semi-structured interview. We registered autoimmune diseases and measured autoantibodies, hormone levels and HLA types. Results: Twenty-eight (47%) patients had hypoparathyroidism or a history of neonatal or transient hypocalcemia. Fifteen patients had neonatal hypocalcemia. Fourteen patients had permanent hypoparathyroidism including seven (54%) of those above age 15 years. A history of neonatal hypocalcemia did not predict later occurring hypoparathyroidism. Parathyroid hormone levels were generally low indicating a low reserve capacity. Twenty-eight patients were positive for autoantibodies. Six (10%) persons had developed an autoimmune disease, and all were females (P<0.02). Hypoparathyroidism correlated with autoimmune diseases (P<0.05), however, no antibodies were detected against the parathyroid glands. Conclusions: Hypoparathyroidism and autoimmunity occur frequently in the 22q11.2 DS. Neonatal hypocalcemia is not associated with later development of permanent hypoparathyroidism. Hypoparathyroidism may present at any age, also in adults, and warrants regular measurement of calcium levels. Hypoparathyroidism and autoimmunity occur frequently together. Our findings of autoimmune diseases in 10% of the patients highlight the importance of stringent screening and follow-up routines.
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