0000000000425219
AUTHOR
Andreas Opitz
The PTPN22gain-of-function+1858T(+) genotypes correlate with low IL-2 expression in thymomas and predispose to myasthenia gravis
Protein tyrosine phosphatase, non-receptor type 22 (PTPN22) inhibits T-cell activation and interleukin-2 (IL-2) production. The PTPN22(gain-of-function)+1858T(+) genotypes predispose to multiple autoimmune diseases, including early-onset (non-thymomatous) myasthenia gravis (MG). The disease association and the requirement of IL-2/IL-2 receptor signaling for intrathymic, negative T-cell selection have suggested that these genotypes may weaken T-cell receptor (TCR) signaling and impair the deletion of autoreactive T cells. Evidence for this hypothesis is missing. Thymoma-associated MG, which depends on intratumorous generation and export of mature autoreactive CD4(+) T cells, is a model of au…
A CTLA4high genotype is associated with myasthenia gravis in thymoma patients
Myasthenia gravis (MG) in thymoma patients depends critically on intratumorous generation and export of mature autoreactive CD4+ T cells. Why non-MG thymomas fail to produce CD4+ T cells is unknown. We studied three single-nucleotide polymorphisms of the cytotoxic T-lymphocyte–associated antigen 4(CTLA4) gene in thymoma patients, nonthymoma early-onset MG patients, and control subjects. Surprisingly, the CTLA4high genotype +49A/A, which is protective against several autoimmune diseases, exerted a prominent predisposing effect to paraneoplastic MG in thymoma patients. The unusual disease association with a CTLA4high genotype implies a unique pathogenesis of paraneoplastic MG, with high CTLA4…
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 …