Spatial Transcriptional Mapping Reveals Site-Specific Pathways Underlying Human Atherosclerotic Plaque Rupture

Abstract

Background: Atherosclerotic plaque ruptures, triggered by blood flow-associated biomechanical forces, cause most myocardial infarctions and strokes.

Objectives: This study aims to investigate the exact location and underlying mechanisms of atherosclerotic plaque ruptures, identifying therapeutic targets against cardiovascular events.

Methods: Histology, electron microscopy, bulk and spatial RNA sequencing on human carotid plaques were studied in proximal, most stenotic, and distal regions along the longitudinal blood flow direction. Genome-wide association studies were used to examine heritability enrichment and causal relationships of atherosclerosis and stroke. Associations between top differentially expressed genes (DEGs) and preoperative and postoperative cardiovascular events were examined in a validation cohort.

Results: In human carotid atherosclerotic plaques, ruptures predominantly occurred in the proximal and most stenotic regions but not in the distal region. Histologic and electron microscopic examination showed that proximal and most stenotic regions exhibited features of plaque vulnerability and thrombosis. RNA sequencing identified DEGs distinguishing the proximal and most stenotic regions from the distal region which were deemed as most relevant to atherosclerosis-associated diseases as shown by heritability enrichment analyses. The identified pathways associated with the proximal rupture-prone regions were validated by spatial transcriptomics, firstly in human atherosclerosis. Of the 3 top DEGs, matrix metallopeptidase 9 emerged particularly because Mendelian randomization suggested that its high circulating levels were causally associated with atherosclerosis risk.

Conclusions: Our findings show plaque site-specific transcriptional signatures associated with proximal rupture-prone regions of carotid atherosclerotic plaques. This led to the geographical mapping of novel therapeutic targets, such as matrix metallopeptidase 9, against plaque rupture.

Keywords: Mendelian randomization; RNA sequencing; atherosclerosis; spatial transcriptomics; vulnerable plaques.