Atherosclerotic fibrous plaques in females are characterized by endothelial-to-mesenchymal transition and linked to smoking

BackgroundSex and plaque histology are intertwined, with fibrous atherosclerotic plaques being more prevalent in women and pointing to general smooth muscle cell plasticity and estrogen signaling. Plaque erosion, a significant contributor to acute coronary syndromes (ACSs), is linked to fibrous plaques and is more prevalent in women as compared to men. We hypothesize that the molecular drivers of histologically determined fibrous plaques differ between men and women. MethodsHuman end-stage atherosclerotic plaques were isolated from consecutive patients who underwent carotid endarterectomy and were included in the Athero-Express biobank. Fibrous plaques from both female and male patients were histologically assessed and further processed to obtain protein, bulk RNA, single-cell RNA and DNA methylation data. We leveraged sex-differential expression and deconvolution analyses to uncover sex-biased molecular mechanisms and cellular dynamics which were experimentally validated using an EndMT in vitro model. ResultsOut of 1,889 atherosclerotic plaques (1,309 male and 580 female), fibrous lesions were observed in 50% of female (n=290) and 31% of male patients (n=416). Compared to patients with atheromatous plaques (n=494), women with fibrous plaques exhibited a higher prevalence of smoking (41% vs. 33%), while men with fibrous plaques presented more often with diabetes (29% vs. 20%). Transcriptional and proteomic phenotyping highlighted more immune-dependent and inflammatory processes in male fibrous plaques. Genes and proteins with higher abundance in female fibrous plaques pointed to endothelial-to-mesenchymal transition (EndMT) and extracellular matrix remodelling. Using single-cell RNA sequencing, we identified a dominant role of endothelial and smooth muscle cells in female plaques, and more macrophages in males. Finally, at the cellular level, we show that sex - specific, smoking-mediated promoter methylation changes may explain these differences. ConclusionsPatients with end-stage fibrous atherosclerotic plaques have a distinct clinical profile, with men more often having diabetes and women more often smoking. This clinical profile associates with sex differences that point to different cellular and molecular compositions of fibrous plaques. These mechanisms might be candidate pathways to understand plaque erosion from a molecular point of view and may provide promising targets for atherosclerosis therapies, as they account for the sex-specific differences in plaque phenotype. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=178 HEIGHT=200 SRC="FIGDIR/small/24314739v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@f3f474org.highwire.dtl.DTLVardef@3606d4org.highwire.dtl.DTLVardef@fa8801org.highwire.dtl.DTLVardef@1f719f4_HPS_FORMAT_FIGEXP M_FIG C_FIG