Macrophage Mincle drives myocardial ischemia-reperfusion injury by recognizing coronary endothelial RTN4
S Ye, G FuAbstract
Background/Introduction
Ischemia-reperfusion (I/R) injury is a critical determinant of prognosis in myocardial infarction patients undergoing revascularization. Macrophage-mediated inflammation plays a pivotal role in the pathogenesis of cardiac I/R injury. Mincle, a pattern recognition receptor (PRR), mediates immune responses through recognition of damage-associated molecular patterns (DAMPs). However, its role in cardiac I/R injury remains largely unknown.
Purpose
To investigate the role of macrophage Mincle in myocardial ischemia-reperfusion injury.
Methods
Transcriptomics, single-cell sequencing, genetic ablation, and bone marrow transfer chimeric models were used to determine the functional significance of macrophage Mincle in myocardial I/R injury. Immune cell infiltration and inflammatory responses were examined by western blot, quantitative real-time PCR, and immunohistochemistry. Co-immunoprecipitation coupled with mass spectrometry, surface plasmon resonance, and mutant plasmid constructs were employed to identify the key domain of RTN4 binding to Mincle. RTN4 activation of Mincle-related pathways was validated through multiple cell biology experiments. Endothelial-specific RTN4 knockdown via AAV was performed to validate the functional relevance of this interaction in vivo.
Results
Following I/R injury, Mincle expression was rapidly upregulated on bone marrow-derived macrophages infiltrating the heart. Myeloid-specific Mincle deficiency significantly improved cardiac function and reduced cardiomyocyte apoptosis, which was associated with downregulation of CXCL1 and GCSF, decreased Ly-6G⁺ neutrophil infiltration and suppressed inflammatory responses. Mechanistically, we identified endothelial RTN4 as a potential ligand for Mincle, with its N-terminal 1-185aa fragment being the critical domain for activating the Mincle/Syk pathway and promoting inflammation. Notably, endothelial cell-specific knockout of RTN4 recapitulated the protective effects against I/R injury, whereas exogenous administration of the RTN4 1-185aa peptide abolished this protection, underscoring the functional relevance of this ligand-receptor interaction in intercellular crosstalk.
Conclusion(s)
Our results reveal a pivotal role of Mincle-RTN4 interaction in driving myocardial ischemia-reperfusion injury. Targeting this ligand-receptor interaction represents a novel and viable therapeutic strategy to limit cardiac damage.