Micro-RNA and mRNA Profiles Associated with Ectopic Germinal Center Formation in Thymus Samples of Patients with Autoimmune Myas

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder caused by antibodies directed against proteins present at the post-synaptic surface of neuromuscular junction (NMJ). A characteristic pathology of patients with early onset MG is thymic hyperplasia with ectopic germinal centers (GC). However, mechanisms that trigger and maintain thymic hyperplasia are poorly characterized. Micro-RNAs (miRNA) are small, non-coding RNAs that are increasingly appreciated to be involved in the pathology of several autoimmune diseases. In order to determine the central mechanisms involved in the pathology, thymus samples from MG patients were assessed by histology and grouped based on appearance of GC compared to samples without them. MiRNA and mRNA were evaluated using GeneChip® miRNA 4.0 Array and GeneChip® Human Transcriptome Array 2.0, respectively. Partek Genomic Suite 6.6 and Transcript Analysis Console 2.0 programs were used for further analysis. Thirty-four mature miRNA and forty eight annotated mRNA transcripts were identified that were differentially expressed between the two groups with greater than 1.5 fold difference in expression (ANOVA p Our study shows that there is a distinct mRNA and miRNA expression pattern in the thymus and maintenance of autoimmunity is supported by regulatory pathways known to be involved in neoplasia

SPP1 Gene Polymorphisms and Response to Glucocorticoid Treatment among Myasthenia Gravis Patients

Oral glucocorticoids (GCs) are the primary therapy for patients with myasthenia gravis (MG). However, wide inter-individual variability exists in treatment response. A cohort of 250 MG subject treated with GCs were involved, and 12 polymorphisms in secreted phosphoprotein 1 (SPP1) gene were longitudinally evaluated for the contribution of response to the initial 3 months of GCs therapy. Improvement ≥ 3 units of Quantitative MG score (QMGS) change for patients with QMGS ＞ 16, ≥ 2 units of QMGS change for patients with QMGS between 2 to 16 or QMGS after treatment becoming zero was judged as being sensitive to GC. The gene product of SPP1, osteopontin (OPN), plasma levels were assessed among MG subjects in relationship clinical parameters including SPP1 genotype. No differences were observed for the allele distribution between GC sensitive/insensitive groups but the rs11728697 C/T + T/T genotypes were more frequent in the GC insensitive group compared to the GC sensitive group (100% versus 64.6%), indicating an association of rs11728697*T allele with GC insensitivity (pdominant = 0.018; OR = 1.065). One risk haplotype (AGTACT) was identified (p = 0.003, OR = 5.81) in the GC insensitive group compared with GC sensitive group. Mean OPN levels were higher among MG subjects (68.3 ± 43.0 ng/ml) compared to healthy controls (50.2 ± 38.7 ng/ml; p = 0.013). There was no association between OPN concentrations and the GC sensitive haplotypes. The genotypes and the haplotype with rs11728697*T allele in SPP1 gene were identified to be associated with insensitivity to GCs treatment and elevations in OPN plasma levels were found in the population of MG subjects. OPN may contribute to MG pathogenesis and treatment response in a select population of MG patients