FRI0439 The Role of the Myeloid Inflammatory Bone Marrow Compartment in Onset and Progression of Myocardial Fibrosis in Systemic Sclerosis

Abstract

BackgroundOne of the major causes of death in systemic sclerosis (SSc) patients is heart involvement which phenotypically resembles inflammatory dilated cardiomyopathy (iDCM) [1]. Recent investigations in animal models of iDCM have demonstrated that the main source of pathological myofibroblasts originates from the bone marrow [2].ObjectivesWe hypothesized that the monocyte/macrophage compartment is responsible for the onset and progression of myocardial fibrosis in SSc. Therefore, we studied the differentiation potential of this cellular compartment and their interaction with stromal and lymphoid cell compartments.MethodsWe isolated CD14+ monocytes from the peripheral blood of SSc patients and healthy subjects and differentiated them towards a myofibroblast phenotype by stimulation with TGF-β1, IL-1β, IL-4, IL-10 and IL-13. After 7 days, cells were screened for expression of the myofibroblast marker genes α-smooth muscle actin (αSMA), fibronectin and collagen I, and Fra-2 and Wnt gene expression. Additionally, we established a coculture system allowing direct coculture of monocytes with human fibroblasts or T-cells in order to analyse the role of direct and indirect cell-to-cell-interaction on both monocyte and fibroblast differentiation.ResultsCD14+ monocytes differentiated towards a myofibroblast phenoypte as demonstrated by upregulation of αSMA (9.6 fold), fibronectin (380 fold) and collagen I (32.5 fold). This process involves Fra-2 signaling (2.2 fold upregulation) and Wnt signaling (Wnt-1 and Wnt-5a only detectable in stimulated cells). Inhibitor studies demonstrated that canonical TGF-β1 signaling is crucial for differentiation, although the application of TGF-β1 alone is not sufficient to induce in vitro differentiation in monoculture. However, direct coculture of monocytes with fibroblasts induced upregulation of αSMA (9.6 fold), fibronectin (150 fold) and collagen I (900 fold) in the presence of TGF-β1. In direct coculture with stimulated T-cells, monocytes also upregulated myofibroblast marker genes even without the addition of cytokines.ConclusionsWe showed that monocytes from the peripheral blood have the potential to differentiate towards a myofibroblast phenotype and therefore represent a potential cellular source for pathological myofibroblasts in SSc. In vivo, this differentiation might be driven by the interaction with stimulated T-cells and resident fibroblasts. A deeper insight into the pathways that drive this process might present a novel strategy to develop disease modifying treatment for SSc in general and in heart involvement in particular.ReferencesVenalis P et al., Cardiomyopathy in murine models of systemic sclerosis. Arthritis & Rheumatology. 2014 [epub ahead of print]Kania G et al., Heart-infiltrating prominin-1+/CD133+ progenitor cells represent the cellular source of transforming growth factor beta-mediated cardiac fibrosis in experimental autoimmune myocarditis. Circulation research. 2009;105(5):462-70.Disclosure of InterestV. Haunerdinger: None declared, E. Pachera: None declared...

LncRNA MHRT Promotes Cardiac Fibrosis via miR-3185 Pathway Following Myocardial Infarction

“…35) Studies have also shown that TGF-β1 can stimulate CFs to transform into myofibroblasts, induce CFs to synthesize matrix metalloproteinases, and cause ventricular remodeling. 36) To reduce MF after MI, extensive studies have investigated the mechanisms of MF MI. 37) LncRNAs can regulate gene expression, sponge miRNAs, and regulate cell transcription and translation.…”