Abstract P1018: Bone Marrow Progenitor Cell-Derived Exosomes Activate Cardiac Fibroblasts Via Mir-21a-5p Mediated Integrin Alpha V Stabilization

Abstract

Abstract: Heart failure is leading cause of death worldwide, and cardiac fibrosis is the hallmark of heart failure. We previously showed that interleukin-10 (IL10) treatment significantly reduces pressure overload-induced cardiac fibrosis. We also have demonstrated that fibroblast progenitor cells (bone marrow-prominin positive cells; FPCs) play a prominent role in developing cardiac fibrosis, yet the mechanism is largely unknown. Here, we hypothesized that pro-fibrotic miRNAs enriched in exosomes derived from IL10 KO FPCs promote fibroblast activation and cardiac fibrosis in pressure-overloaded myocardium. Methods: Exosomes were isolated from WT and IL-10KO FPCs. Exosomal miRNAs profiling was performed using fibrosis-associated miRNA profiler kit from Qiagen. To determine the contribution of exosomal miR21 on TAC-induced fibrosis, miR21 level was reduced in FPCs-derived exosomes using miR21 silencer. Modified exosomes were injected into heart immediately after TAC surgery. Results: FPCs were identified as CD45+/prominin-1 cells using FACS. TGFβ treatment exacerbated fibrotic genes (Col1α, fibronectin, periostin, and αSMA) expression in IL10KO FPCs compared to WT-FPCs. Pathway-based miRNA array revealed that IL10KO FPCs exosomes are enriched with miR-21a-5p and facilitated fibroblasts activation as observed by qPCR (αSMA and Col1α), western (Col1α and TGFβ levels), wound healing, and immunostaining assay (Col1α/DAPI expression) as compared to WT control. Interestingly, miR21 inhibition in IL10KO FPCs exosome using antimiR 21, reduced TGFβ-induced cardiac fibroblast activation. Target prediction database analysis revealed that Integrin Subunit Alpha V (ITGAV) is a strong regulatory target for miRNA21. At molecular level, we found that exosomal miR-21a-5p stabilizes ITGAV, which ultimately enhances fibroblast activation and cardiac fibrosis both in vitro and in vivo. Conclusions: In conclusion, we report that FPCs derived miR21 packaged in exosomes activates cardiac fibroblasts in IL10-KO mice via miR-21a-5p/ITGAV/Col1α signaling axis and increased cardiac fibrosis. IL10 treatment significantly reduced miR21 exosomal packaging, inhibited fibroblasts activation, and reduced cardiac fibrosis following TAC.