Correlation of computed tomography with carotid plaque transcriptomes associates calcification with lesion-stabilization

Abstract

A B S T R A C TBackground and aims: Unstable carotid atherosclerosis causes stroke, but methods to identify patients and lesions at risk are lacking. We recently found enrichment of genes associated with calcification in carotid plaques from asymptomatic patients. Here, we hypothesized that calcification represents a stabilising feature of plaques and investigated how macro-calcification, as estimated by computed tomography (CT), correlates with gene expression profiles in lesions. Methods: Plaque calcification was measured in pre-operative CT angiographies. Plaques were sorted into high-and lowcalcified, profiled with microarrays, followed by bioinformatic analyses. Immunohistochemistry and qPCR were performed to evaluate the findings in plaques and arteries with medial calcification from chronic kidney disease patients. Results: Smooth muscle cell (SMC) markers were upregulated in high-calcified plaques and calcified plaques from symptomatic patients, whereas macrophage markers were downregulated. The most enriched processes in high-calcified plaques were related to SMCs and extracellular matrix (ECM) organization, while inflammation, lipid transport and chemokine signaling were repressed. These findings were confirmed in arteries with high medial calcification. Proteoglycan 4 (PRG4) was identified as the most upregulated gene in association with plaque calcification and found in the ECM, SMA+ and CD68+/TRAP + cells. Conclusions: Macro-calcification in carotid lesions correlated with a transcriptional profile typical for stable plaques, with altered SMC phenotype and ECM composition and repressed inflammation. PRG4, previously not described in atherosclerosis, was enriched in the calcified ECM and localized to activated macrophages and smooth muscle-like cells. This study strengthens the notion that assessment of calcification may aid evaluation of plaque phenotype and stroke risk.

Proteoglycan 4 is Increased in Human Calcified Aortic Valves and Enhances Valvular Interstitial Cell Calcification

“…PRG4 protein further localized at and in the proximity of valvular calcification processes. In line with our results, PRG4 expression is increased in calcified atherosclerotic plaques, specifically in plaques from symptomatic patients [16]. This increase in PRG4 in calcified valvular and vascular tissues taken together with an upregulation of PRG4 mRNA levels in VICs in response to high phosphate conditions, BMP2, and TGF-β suggests a possible role of PRG4 in VIC differentiation and calcification.…”

“…Importantly, these observations have been confirmed with proteomics, revealing that fibrotic parts of the valve present higher levels of proteoglycans [15], specifically proteoglycan 4 (PRG4). Furthermore, PRG4 upregulation has been identified in calcified atherosclerotic plaques [16], suggesting a relationship between PRG4 and cardiovascular calcification. Given the link between valvular proteoglycans and calcification, the aims of the current study were to determine the expression of PRG4 in the aortic valve and its role in VIC mediated calcification.…”

Extracellular vesicle signalling in atherosclerosis

“…Vascular calcification is the process of accumulation of minerals to intima or media of the vessel wall, and is present in the late stages of atherosclerosis [ 42 ]. Plaque calcification is linked to plaque stability, stable fibrous cap formation and reduced macrophage infiltration [ [43] , [44] , [45] ]. Shaalan et al, suggested that quantification of calcified area could be a novel marker to assess cerebrovascular ischemic event risk [ 44 ].…”

Corporate social responsibility and stakeholder engagement in Ghana’s mining sector: a case study of Newmont Ahafo mines

“…Data was then coded, decreased to size, the topics from the text segments were outlined, constructed the networks, similar and consistent groups were arranged and categorized, the thematic network was analyzed, the network was summarized and patterns were constructed sequentially (Brunson & Laubenbacher, 2018). Thematic analysis goes further than counting explicit words or phrases, and concentrates on the identification and description of ideas both implicit and explicit (Karlöf et al, 2019;Sodhi & Tang, 2018). Additionally, exact quotes from the respondents were incorporated into the discussion.…”

“…In conducting qualitative studies, Karlöf et al (2019) argues that "there is no right or wrong answer, but some methods will be better choices than others for particular research topics" (p. 103). In this study, we used competing perspectives from various stakeholders of Newmont Ahafo Ltd. in order to enhance validity and reliability (Adusei, 2017).…”