Transcriptomic profiling identifies tumor necrosis factor receptor-associated factor (TRAF)-5 expression in human atherosclerotic plaques as a predictor of future cardiovascular events

AIM OF THE STUDY: Tumor necrosis factor receptor-associated factors (TRAFs) are cytoplasmic adapter proteins that regulate immune cell signaling downstream of TNF, interleukin-1, and Toll-like receptors. Although preclinical data implicate TRAFs in atherogenesis, their clinical relevance in human disease remains unknown. We aimed to characterize TRAF1-7 expression in human atherosclerotic plaques and determine associations with plaque phenotype, cardiovascular outcomes and cellular functions.

MAIN FINDINGS: TRAF1-7 expression was compared between early and advanced carotid plaques using bulk transcriptomics. Prognostic relevance was assessed in 616 carotid endarterectomy specimens from the Athero-Express Biobank using multivariable Cox regression adjusted for age, sex, diabetes, diastolic blood pressure, eGFR, and peripheral arterial disease. Major adverse cardiovascular events (MACE) comprised nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death within 3 years. Potential TRAF5-dependent immune cell mechanisms were explored by single-cell RNA sequencing (scRNA-seq) of 259,493 cells from 79 human plaques. Among all TRAFs, only TRAF5 was significantly downregulated in advanced lesions. Higher lesional TRAF5 expression independently predicted lower risk for MACE (HR 0.62; 95% CI 0.40-0.98). TRAF5 was lowest in fibro-inflammatory and unstable plaques. scRNA-seq identified B cells as the predominant TRAF5-expressing population. TRAF5+ B cells showed downregulation of pro-inflammatory pathways and upregulation of immunoregulatory mediators such as TGF-β2 and IL-13. Gene-set enrichment analyses confirmed attenuated inflammatory activation and B cell receptor signaling in TRAF5+ B cells.

CONCLUSIONS: TRAF5 expression identifies a stable, less inflammatory plaque phenotype and independently predicts reduced cardiovascular risk after carotid endarterectomy positioning it as a potential biomarker for personalized cardiovascular risk stratification.