0000000000634068
AUTHOR
Nick Willcox
Autoimmune associations and autoantibody screening show focused recognition in patient subgroups with generalized myasthenia gravis
Autoimmune associations in myasthenia gravis (MG)-patients and their relatives have not been re-assessed since their separation into early- or late-onset MG (EOMG, LOMG), or thymoma-associated MG. Here, we analysed 226 EOMG-, 97 LOMG-, and 150 thymoma-patients for autoimmune disorders in themselves and their relatives. From 283 of them sera were tested for different organ- and non-organ-specific autoantibodies (autoAbs) by immunofluorescence test (IFT) and ELISA; genotyping was performed in 213 patients. Relatives with autoimmune disorders were reported by more patients with EOMG (40% of 210) than LOMG (20% of 89; p0.01) than thymomas (8% of 150; p0.001). In 150 genotyped EOMG-females, the …
The ageing and myasthenic thymus: a morphometric study validating a standard procedure in the histological workup of thymic specimens.
The thymus is believed to play an important role in the pathogenesis of myasthenia gravis (MG). The 80% of MG patients with anti-acetylcholine receptor autoantibodies fall into three clinical subgroups: 1) thymoma; 2) early-onset MG (<age of 40; EOMG) and 3) late-onset (LOMG; onset after 40). Thymectomy is widely used in EOMG, but its benefits have not been established in randomized controlled trials. A multicenter international trial (MGTX) currently seeks to determine whether thymectomy reduces corticosteroid requirements, and to look for correlations with thymic histology. We here describe the validated, standardized histological workup and reporting system used in this trial.
Deficiency of the autoimmune regulator AIRE in thymomas is insufficient to elicit autoimmune polyendocrinopathy syndrome type 1 (APS‐1)
Thymomas are thymic epithelial neoplasms, associated with a variety of autoimmune disorders (especially myasthenia gravis), that apparently result from aberrant intra-tumourous thymopoiesis and export of inefficiently tolerized T-cells to the periphery. The autoimmune regulator (AIRE) drives the expression of self-antigens in the thymic medulla and plays an essential role in ‘central’ tolerance in both humans and mice. However, while inactivating AIRE mutations result in the ‘autoimmune polyendocrinopathy syndrome type 1’ (APS-1), its major features are not well reproduced in AIRE-knock-out mice. Therefore, alternative human disease scenarios with concomitant AIRE deficiency may be valuable…
Late-onset myasthenia gravis - CTLA4(low) genotype association and low-for-age thymic output of naïve T cells.
Abstract Late-onset myasthenia gravis (LOMG) has become the largest MG subgroup, but the underlying pathogenetic mechanisms remain mysterious. Among the few etiological clues are the almost unique serologic parallels between LOMG and thymoma-associated MG (TAMG), notably autoantibodies against acetylcholine receptors, titin, ryanodine receptor, type I interferons or IL-12. This is why we checked LOMG patients for two further peculiar features of TAMG – its associations with the CTLA4 high/gain-of-function +49A/A genotype and with increased thymic export of naive T cells into the blood, possibly after defective negative selection in AIRE-deficient thymomas. We analyzed genomic DNA from 116 …
Thymoma and paraneoplastic myasthenia gravis
Paraneoplastic autoimmune diseases associate occasionally with small cell lung cancers and gynecologic tumors. However, myasthenia gravis (MG) occurs in at least 30% of all patients with thymomas (usually present at MG diagnosis). These epithelial neoplasms almost always have numerous admixed maturing polyclonal T cells (thymocytes). This thymopoiesis-and export of mature CD4(+)T cells-particularly associates with MG, though there are rare/puzzling exceptions in apparently pure epithelial WHO type A thymomas. Other features potentially leading to inefficient self-tolerance induction include defective epithelial expression of the autoimmune regulator (AIRE) gene and/or of major histocompatib…
The Autoimmune Regulator AIRE in Thymoma Biology: Autoimmunity and Beyond
Thymomas are tumors of thymic epithelial cells. They associate more often than any other human tumors with various autoimmune diseases; myasthenia gravis is the commonest, occurring in 10-50% of thymoma patients, depending on the World Health Organization-defined histologic subtype. Most thymomas generate many polyclonal maturing T lymphocytes but in disorganized microenvironments Failure to induce self-tolerance may be a key factor leading to the export of potentially autoreactive CD4 progeny, thus predisposing to autoimmune diseases. Normally, the master Autoimmune Regulator promotes expression of peripheral tissue-restricted antigens such as insulin by medullary thymic epithelial cells a…