Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose: Monozygotic twins discordant for JDM are rare, composing only 1% of our entire registry of 525 JM patients. These individuals represent a unique opportunity identify persistent gene expression differences in JDM children by allowing for a control with an identical genome, as well as environmental control with respect to early development
Methods: We recruited a pair of monozygotic, white, male twins discordant for Juvenile Dermatomyositis (JDM), age 9.5 years, and a race, sex matched 7.2 year old control for this IRB approved study. The JDM+ twin (MSA=probably MJ positive) held his medications (oral prednisone 7 mg, Sub Q MTX 12.5 mg) on the morning of the blood draw. We isolated PBMCs within two hours of blood draw and expanded erythroblasts in culture for 9-12 days. We induced pluripotentcy by transduction with Sendai virus carrying Oct3/4, Sox2, Klf4, and cMyc. After documenting normal karyotypic analysis, we profiled the transcriptomes of 3 separate clones from each of the three individuals to detect persistent JDM gene expression differences.
Results: In the comparison of the JDM iPSC clones to the unrelated control, three algorithms only agreed on 11 differentially expressed (DE) genes out of 54 total. This included increased expression of HLA-DQB1 (FC 7.6-7.8) and SRD5A3 (FC 2.1), but decreases in expression for MTRNR2L8 (FC -5.6) and ZNF718 (FC -2.6) in the JDM-derived cells. 2 of 3 algorithms agreed that the JDM-derived clones also had increased expression of HLA-DRB1 (FC 4.8). However, virtually the same genes were DE in the unaffected twin compared to the control. Comparing the JDM affected twin and the unaffected twin clones revealed one gene (ZDBF2) of only nominal significance for decreased expression in the JDM clones (adj. p-value 0.10, FC -1.6). Clustering of the top 50 genes from the JDM – control comparison along with ZDBF2 demonstrated that the twins cluster with each other, rather than the unaffected twin clustering with the unrelated control.
Conclusion: 1) iPSC generation reprograms any baseline JDM disease signatures from the original PBMCs. 2) There are inter-individual genetic differences that affect baseline gene expression, as evidenced by the shared expression patterns between discordant twins. Speculation: Genetic factors increase risk for developing JDM, but the initiation of the disease process requires a trigger. It remains to be seen if JDM iPSCs manifest persistent epigenetic changes that prime them for an inflammatory response when presented with a suitable antigenic stimulus.
To cite this abstract in AMA style:Roberson EDO, Cao L, Morales-Heil DJ, Xu D, Galat Y, Galat V, Tarvin S, Huang CC, Pachman LM. Juvenile Dermatomyositis Patient-Derived Induced Pluripotent Stem Cells Do Not Retain Disease Expression Signatures [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/juvenile-dermatomyositis-patient-derived-induced-pluripotent-stem-cells-do-not-retain-disease-expression-signatures/. Accessed February 23, 2020.
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