Abstract 333: TNF Receptor Modulation of Progenitor Cells and Exosomes for Myocardial Repair
Garikipati, VN; Cimini, M; Wang, C; Roy, R; Cheng, Z; Truongcao, MM; Benedict, C; Verma, SK; Koch, WJ; Kishore, R; Goukassian, DA
Published in: Circulation Research
Our published studies, using TNFR1 and TNFR2 knockout (KO) mice have demonstrated that negative effects of TNF during ischemic tissue repair including enhanced apoptosis and inflammatory cytokines expression and signaling, is largely mediated by TNFR1/p55. Our hypothesis is that inhibition of TNF-TNFR1 signaling inhibits multiple negative effects of TNF after myocardial ischemia by promoting TNF signaling through protective TNFR2 receptor and thereby augmenting EPC-mediated myocardial angiogenesis and repair and this enhanced protective effect of TNFR1 KO EPCs may involve alteration in the cargo and function of TNFR1-KO EPC derived exosomes.Protective effect of disrupted TNF-TNFR1/p55 signaling in BM-EPCs under stress conditions in WT, p55KO and p75KO EPCs were tested in tube formation assay under hypoxia conditions and H2O2 treatment. In the absence of TNFR1 (p55KO EPCs) - EC function of BM-EPCs is enhanced under normoxia/hypoxia conditions and survival of BM-EPCs is increased under oxidative stress. To test the effect of TNFR1 and TNFR2 loss in the BM-EPCs for recovery after AMI, WT mice were subjected to AMI and WT, p75KO and p55KO BM-EPCs were injected into the myocardium immediately after AMI. Compared to WT and p75KO, injection of p55KO EPCs into WT hosts led to - increased retention of p55KO EPCs in the WT mice hearts; decreased post-MI apoptosis in WT mice; increased vascular network; significantly improved cardiac function; substantially small infarct size; the last three indicating improved cardiac remodeling by day 21 post-AMI. Further, in vitro exosome studies showed that compared to WT and p75KOs, p55KO BM-EPCs-derived exosomes showed positive activities in vitro, including - enhanced angiogenic function in HUVECs and increased survival of H9C2 cells. These effects were mediated via upregulation of miRNA-191-5p as shown by increased levels of angiogenic miR-191-5p in the exosomal cargo of p55KO EPCs and near complete inhibition of HUVEC angiogenic function in vitro by miR-191-5p-antagomiR.Our findings suggest that decrease/loss of TNFR1 modulates both the content and function of EPC exosomes and enhance reparative and angiogenic capabilities of EPCs and EPC-mediated vascular and anatomical repair in the MI model.
