Spatially clustered type I interferon responses at injury borderzones

Sterile inflammation after myocardial infarction (MI) is classically credited to myeloid cells interacting with dead cell debris in the infarct zone (IZ). Here, we show that borderzone cardiomyocytes are the dominant initiators of a novel type I interferon (IFN) response in the infarct borderzone zone (BZ). Using spatial transcriptomics analysis of mice and humans, we find that MI induces colonies of interferon induced cells (IFNICs) expressing interferon stimulated genes (ISGs) decorating the BZ, where cardiomyocytes experience mechanical stress, nuclear rupture, and escape of chromosomal DNA. Cardiomyocyte-selective deletion of interferon regulatory factor 3 (Irf3) abrogated IFNIC colonies, whereas mice lacking Irf3 in fibroblasts, macrophages, neutrophils, or endothelial cells; Ccr2-deficient mice; or plasmacytoid dendritic cell-depleted mice did not. IFNs blunted the protective matricellular programs and contractile function of BZ fibroblasts, and increased vulnerability to pathologic remodeling. In mice that died after MI, IFNIC colonies were immediately adjacent to sites of ventricular rupture, while mice lacking IFNICs were protected from rupture and exhibited improved survival. Together, these results reveal a pathologic BZ niche characterized by a cardiomyocyte-initiated innate immune response. We suggest that selective inhibition of Irf3 activation in non-immune cells of the borderzone could limit ischemic cardiomyopathy while avoiding broad immunosuppression.