Integrative immune profiling and translational validation identify a myeloid inflammatory biomarker signature for acute myocardial infarction

Acute myocardial infarction (AMI) is accompanied by rapid systemic immune-inflammatory remodeling, but blood-based, clinically interpretable biomarkers that capture this response remain incompletely defined. This study aimed to identify and validate a reproducible myeloid inflammatory biomarker signature for AMI through integrative immune profiling, machine-learning analysis, and experimental validation. Peripheral blood transcriptomic datasets were obtained from GEO, with GSE123342 as the discovery cohort and GSE66360, GSE59867, and GSE48060 as independent validation cohorts. Differential expression analysis, cross-cohort replication, functional enrichment, marker-based immune profiling, machine-learning feature selection, ROC analysis, longitudinal evaluation, and THP-1 macrophage validation were performed. AMI was associated with coordinated transcriptional remodeling dominated by neutrophil activation, myeloid leukocyte migration, cytokine signaling, complement activation, and TNF/NF-kappaB-related inflammatory pathways. Cross-cohort integration identified a four-gene myeloid inflammatory signature consisting of AQP9, S100A9, CD163, and LILRA5, with additional biological context provided by TREM1 and IL1R2. The signature showed consistent diagnostic performance across cohorts, with AUC values of 0.824, 0.893, 0.911, and 0.788 in GSE123342, GSE66360, GSE59867, and GSE48060, respectively. Longitudinal analyses showed that the signature was strongest in the acute phase. qPCR and ELISA validation confirmed inflammatory induction of candidate genes and secreted mediators in stimulated THP-1 macrophages. This study identifies an externally validated myeloid immune-inflammatory signature for AMI and supports the value of integrative immune profiling for precision biomarker discovery in inflammatory cardiovascular disease.