Transcriptomic signature of trained immunity associates with the extent of coronary artery disease in acute coronary syndrome

Background Atherosclerosis is a chronic inflammatory disease exacerbated by innate immune activation. Trained immunity, characterised by metabolic reprogramming and enhanced inflammatory response of innate immune cells, has been implicated in atherosclerotic cardiovascular disease (ASCVD) and provides a potential therapeutic target. Purpose To establish whether functional characteristics of "trained" phenotype in peripheral monocytes is associated with extent of coronary artery disease (CAD) in acute coronary syndrome (ACS). Methods In 56 participants who had presented with non-STE ACS, peripheral blood mononuclear cells (PBMCs) and plasma were isolated at follow-up, median 56 (range 45-81) days from discharge. PBMCs were cultured in DMEM (5mM glucose), rested overnight, then stimulated with LPS 100ng/mL and IFNγ 10ng/mL (M1) or left unstimulated (M0). Monocytes were positively selected from these PBMCs for bulk RNA sequencing. To quantify pathway activity, Gene Set Variation Analysis (GSVA) was used to assign enrichment scores for 50 predefined Hallmark gene sets (Broad Institute) to each sample, based on ranked gene expression. To examine inflammatory responsiveness, we calculated the change in pathway activity for each participant as the difference between stimulated (M1) and unstimulated (M0) monocytes. Pathways with correlated stimulation-induced activity were grouped into modules using unsupervised hierarchical clustering. In this way, correlated pathway responses were condensed into a smaller number of biologically meaningful modules, then principal component analysis (PCA) was used to derive composite scores summarising the shared activity between modules. Results Two modules reflecting key features of trained immunity were identified: an interferon signalling module, and a metabolic module comprising oxidative phosphorylation pathways. Participants were dichotomised according to the median composite score derived from these modules. A lower score—characterised by reduced oxidative phosphorylation pathway activity together with enhanced interferon signalling following stimulation—was associated with greater coronary disease burden (median SYNTAX 29 [21.5–34.6] vs 18 [11.0–26.0], p=0.009). In multivariable linear regression adjusting for age, sex, BMI, and diabetes, the composite score remained independently associated with SYNTAX score (p=0.04). No significant associations were observed between the score and plasma CRP, IL-6, or IL-18 levels. Conclusion A peripheral monocyte phenotype consistent with trained immunity—defined by impaired oxidative phosphorylation coupled with enhanced interferon signalling—is associated with more extensive coronary artery disease. These findings support transcriptomic profiling of innate immune reprogramming as a strategy to identify patients who may derive greatest benefit from targeted anti-inflammatory therapies.