Abstract 16201: Exosomal Y RNA Fragment Alters Macrophage Il-10 Gene Expression And Secretion, Conferring Cardioprotection Following Ischemia/reperfusion Injury
Background: Exosomes secreted by cardiosphere-derived cells (CDCs) mediate regeneration and cardioprotection after ischemia/reperfusion (I/R) injury. CDC-secreted exosomes (CDC-exo) reduce infarct size after I/R by delivering bioactive noncoding RNAs to target cells, including macrophages. By previous RNA-sequencing analysis, we identified a unique Y RNA fragment Yb highly enriched in CDC-exo.
Objective: We sought to clarify the role, if any, of Yb as a mediator of the cardioprotection observed with CDC-exo treatment following I/R.
Methods: To investigate the role of this specific Y RNA fragment, we directly transfected bone marrow derived-macrophages (BMDMs) with Yb. Gene/protein expression analyses and chromatin immunoprecipitation (ChIP)-sequencing were performed to evaluate transcriptional and epigenetic modifications. Mass spectrometry and RNA pull-down were done to identify protein partners. Potential cytoprotective effects were examined on cardiomyocytes subjected to oxidative stress and cocultured with Yb-primed macrophages. The role of Yb was also assessed in vivo in a rat model of I/R injury.
Results: Yb induced transcription and protein secretion of IL-10 when directly transfected into BMDMs, leading to acetylation of H3K27 at the Il10 locus as well as promoter activation. These effects underlie an observed increased and sustained release of IL-10 by BMDMs. We identified the ribonucleoprotein HnrpH1 as a critical binding partner of Yb. Moreover, Yb-primed BMDMs were cytoprotective against oxidative stress in cardiomyocytes (24.1±4.8% apoptosis rate vs. 42.9±6.7% with scramble-primed BMDMs; p=0.0002); this cytoprotection was abrogated by co-incubation with a blocking antibody against IL-10. Intracoronary injection of Yb in rats 10 min post I/R showed scar mass reduction after 48h (Yb: 24.3±2.8 mg; scramble: 67.4±10.9 mg; p<0.01).
Conclusions: Yb, a Y RNA-derived fragment highly enriched in CDC-exo, contributes to cardioprotection by increasing Il10 expression, leading to enhanced IL-10 protein secretion. Yb increases Il10 expression via promoter activation and epigenetic modifications. Thus, this small noncoding RNA of previously unknown biological activity contributes to the therapeutic effects of CDC-exo.
Author Disclosures: L. Cambier: None. G. de Couto: None. A. Ibrahim: Employment; Significant; Capricor Inc. E. Marbán: Ownership Interest; Significant; Capricor Inc. Consultant/Advisory Board; Significant; Capricor Inc.
- © 2016 by American Heart Association, Inc.