IRF3 and type I interferons fuel a fatal response to myocardial infarction

Abstract

Interferon regulatory factor 3 (IRF3) and type I interferons (IFNs) protect against infections and cancer, but excessive IRF3 activation and type I IFN production cause autoinflammatory conditions such as Aicardi-Goutières syndrome and STING-associated vasculopathy of infancy (SAVI). Myocardial infarction (MI) elicits inflammation, but the dominant molecular drivers of MI-associated inflammation remain unclear. Here we show that ischemic cell death and uptake of cell debris by macrophages in the heart fuel a fatal response to MI by activating IRF3 and type I IFN production. In mice, single-cell RNA-seq analysis of 4,215 leukocytes isolated from infarcted and non-infarcted hearts showed that MI provokes activation of an IRF3-interferon axis in a distinct population of interferon-inducible cells (IFNICs) that were classified as cardiac macrophages. Mice genetically deficient in cyclic GMP-AMP synthase (cGAS), its adaptor STING, IRF3, or the type I IFN receptor IFNAR exhibited impaired interferon-stimulated gene (ISG) expression and, in the case of mice deficient in IRF3 or IFNAR, improved survival after MI as compared to controls. Interruption of IRF3-dependent signaling resulted in decreased cardiac expression of inflammatory cytokines and chemokines and decreased inflammatory cell infiltration of the heart, as well as in attenuated ventricular dilation and improved cardiac function. Similarly, treatment of mice with an IFNAR-neutralizing antibody after MI ablated the interferon response and improved left ventricular dysfunction and survival. These results identify IRF3 and the type I IFN response as a potential therapeutic target for post-MI cardioprotection.

Type I interferon responses to ischemic injury begin in the bone marrow of mice and humans and depend on Tet2, Nrf2, and Irf3

“…Since previous work found the interferon response to be detrimental after MI 14 Fig. 2a-d), reinforcing the view that ISG-expression is orthogonal to the other neutrophil phenotypes observed.…”

“…Single cell transcriptomics was essential for discrimination of ISG+ and ISG-emergency myeloid cell populations because sensitive and specific antibodies for flow cytometric analysis of this pathway are lacking and because ensemble measurement techniques obscure myeloid cell subsets 21,22 . Our data demonstrate that emergency myeloid cells exhibit unrecognized functional heterogeneity with pathologic significance because ISGs include proinflammatory cytokines and chemokines 22,23 and because genetic or pharmacologic inhibition of interferon signaling was previously shown to reduce post-MI inflammation and protect against adverse ventricular remodeling and death due to ventricular rupture 14 .…”

“…2a-g Table 3a). Hrt-N2 neutrophils expressed interferon-stimulated genes (ISGs), which was surprising because previous work showed ISG expression predominantly in monocytederived macrophages on day 4 after MI 14 . Nevertheless, subsetting and reclustering revealed that ISG-expressing neutrophils are identifiable as early as day 1 (Fig.…”

“…Using myocardial infarction (MI) as a model of sterile injury, we performed single cell RNA-Seq on 55,687 neutrophils, monocytes, and macrophages from the heart, blood, and bone marrow of WT mice on days 1-4 after MI as well as from human blood of patients presenting with acute MI. Previously, we discovered that MI induces a deleterious type I interferon response in monocyte-derived macrophages of the infarcted heart on day 4 after MI, and genetic or pharmacologic inhibition of type I interferon signaling was protective by reducing ventricular dilation and improving survival 14 . Here we show that neutrophils and monocytes from the bone marrow, blood and heart exist as mirrored populations of cells expressing (ISG+) or not expressing (ISG-) interferon stimulating genes after MI.…”

Cytosolic sensing of immuno-stimulatory DNA, the enemy within

“…Genetic ablation of Dsba-L, a protein chaperone localized to the mitochondrial matrix, enhanced mtDNA leakage and cGAS–STING activation in adipocytes, while over-expression protected against inflammatory responses and liver damage in obese mice [35,36]. Myocardial infarction also drives a classical IFN-I response downstream of cGAS–STING activation [37]. The mechanism involves extrinsic sensing of cellular debris and self-DNA by cardiac macrophages, and it is not yet known if cell-intrinsic DNA sensing may also play a role in non-myeloid cell types during MI.…”