IFN-γ-Dependent Macrophage Reprogramming Coordinates Inflammatory Resolution and Matrix Remodeling in Heart Regeneration

Heart regeneration requires coordinated immune activation, timely inflammatory resolution, and dynamic extracellular matrix (ECM) remodeling in addition to cardiomyocyte (CM) proliferation. However, the cytokine signals that instruct immune cell functions during cardiac repair remain incompletely understood. Here, we identify interferon-gamma (IFN-{gamma}) as a critical regulator of macrophage plasticity in zebrafish heart regeneration. IFN-{gamma} signaling components are dynamically activated following cardiac injury, with early induction of ifng1 and temporally coordinated receptor expression. Genetic ablation of ifng1 impairs myocardial regeneration, resulting in reduced CM proliferation and persistent fibrotic scarring. Temporal transcriptional profiling reveals sustained inflammatory signatures, impaired efferocytosis, and abolished reparative programs, accompanied by aberrant immune cell dynamics and retention of injury-derived debris in mutant hearts. Transcriptomic analysis of cardiac macrophages further reveals that IFN-{gamma} deficiency disrupts the transition from an inflammatory state to a reparative, ECM-remodeling phenotype, leading to reduced collagen denaturation and diminished CM protrusion at the injury border zone. Inducible- and macrophage-specific blockade of IFN-{gamma} signaling phenocopies defects in global knockout, establishing a cell-autonomous requirement for IFN-{gamma} in coordinating regenerative immune function. Collectively, our findings define an IFN-{gamma}-dependent macrophage reprogramming axis that couples inflammatory resolution to ECM remodeling in heart regeneration, elucidating how cytokine signaling actively instructs tissue repair. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/712551v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@cefbecorg.highwire.dtl.DTLVardef@fd56dborg.highwire.dtl.DTLVardef@517495org.highwire.dtl.DTLVardef@1bd0851_HPS_FORMAT_FIGEXP M_FIG C_FIG