Poster Session B
Myopathic rheumatic diseases (polymyositis, dermatomyositis, inclusion body myositis)
Julie Paik, MD, MHS
Johns Hopkins University
Baltimore, MD, United States
No financial relationships with ineligible companies to disclose
Four patients with IIM-associated myocarditis, four patients with IIM without myocarditis, and 4 healthy controls were included for single cell analyses. The 4 patients with IIM-associated myocarditis were composed of anti-Ku + overlap IIM with scleroderma (n=3), and PL-7 positive anti-synthetase syndrome (n=1). The 4 IIM patients without myocarditis included patients with HMGCR+ immune mediated necrotizing myopathy (n=2) and dermatomyositis (TIF-1 gamma positive and Ro 60 positive (n=2). All patients with myocarditis had elevation in serum troponin-I. All patients were treated with immunosuppression. We identified B cells and T cells based on gene expression signatures (Figure 1). Gene expression analyses demonstrated that peripheral blood B and T lymphocytes from IIM patients with myocarditis had a higher number of differentially expressed genes vs. controls as compared to patients with IIM alone (see Figure 2). Ingenuity pathway analyses of these differentially expressed genes highlighted a remarkable degree of activation of multiple immune response related pathways in B-cells from patients with IIM associated myocarditis that was not observed in patients with IIM alone.
Conclusion: Single cell RNA sequencing of PBMCs suggests that B-cell dysregulation might drive myocardial inflammation in patients with IIM who develop myocarditis.
Figure 1 UMAP plot of scRNA sequencing data from peripheral blood mononuclear cells of patients with idiopathic inflammatory myopathies (IIM), IIM + myocarditis, or controls.
Figure 2. Graphical representation of differential gene expression analysis of peripheral blood B and T cell lymphocytes from IIM patients with myocarditis vs. control (pink) and IIM patients without myocarditis vs. controls (purple)
J. Paik: ArgenX, 2, 5, AstraZeneca, 5, Guidepoint Consulting, 2, Pfizer, 2, Priovant, 5; K. Bermea: None; C. Duque: None; M. Mugnier: None; L. Adamo: i-Cordis, LLC, 8, kiniksa pharmaceuticals, 2.