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Low TLR7 gene expression in atherosclerotic plaques is associated with major adverse cardio- and cerebrovascular events.

ABSTRACT: Processes in the development of atherosclerotic lesions can lead to plaque rupture or erosion, which can in turn elicit myocardial infarction or ischaemic stroke. The aims of this study were to determine whether Toll-like receptor 7 (TLR7) gene expression levels influence patient outcome and to explore the mechanisms linked to TLR7 expression in atherosclerosis.Atherosclerotic plaques were removed by carotid endarterectomy (CEA) and subjected to gene array expression analysis (n?=?123). Increased levels of TLR7 transcript in the plaques were associated with better outcome in a follow-up study over a maximum of 8 years. Patients with higher TLR7 transcript levels had a lower risk of experiencing major cardiovascular and cerebrovascular events (MACCE) during the follow-up period after CEA (hazard ratio: 2.38, P?=?0.012, 95% CI 1.21-4.67). TLR7 was expressed in all plaques by T cells, macrophages and endothelial cells in capillaries, as shown by immunohistochemistry. In short-term tissue cultures, ex vivo treatment of plaques with the TLR7 ligand imiquimod elicited dose-dependent secretion of IL-10, TNF-?, GM-CSF, and IL-12/IL-23p40. This secretion was blocked with a TLR7 inhibitor. Immunofluorescent tissue analysis after TLR7 stimulation showed IL-10 expression in T cells, macrophages and vascular smooth muscle cells. TLR7 mRNA levels in the plaques were correlated with IL-10 receptor (r?=?0.4031, P?

SUBMITTER: Karadimou G

PROVIDER: S-EPMC5220676 | biostudies-other | 2017 Jan

REPOSITORIES: biostudies-other

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Low TLR7 gene expression in atherosclerotic plaques is associated with major adverse cardio- and cerebrovascular events.

Karadimou Glykeria G Folkersen Lasse L Berg Martin M Perisic Ljubica L Discacciati Andrea A Roy Joy J Hansson Göran K GK Persson Jonas J Paulsson-Berne Gabrielle G

Cardiovascular research 20161115 1

<h4>Aims</h4>Processes in the development of atherosclerotic lesions can lead to plaque rupture or erosion, which can in turn elicit myocardial infarction or ischaemic stroke. The aims of this study were to determine whether Toll-like receptor 7 (TLR7) gene expression levels influence patient outcome and to explore the mechanisms linked to TLR7 expression in atherosclerosis.<h4>Methods and results</h4>Atherosclerotic plaques were removed by carotid endarterectomy (CEA) and subjected to gene arra ...[more]

PMID: 27864310

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Project description:One pending issue in cardiovascular epigenetics is whether cerebrovascular events, a major complication of atherosclerosis, are associated with any specific DNA methylation changes in the carotid plaque. To clarify that topic, we profiled the DNA methylomes of human symptomatic carotid plaques (SCPs) obtained from patients who suffered cerebrovascular events (n=19) and asymptomatic counterparts (ACP; n=19) with a high-density microarray (~485,000 CpG sites, Illumina), and crossed DNA methylation data with RNAseq-based expression data from an independent SCP set (n=8). Few (30) CpGs showed a significant (p<0.05; absolute Delta-Beta>0.20) differential methylation between the two groups. Within SCPs, methylation correlated significantly with post-cerebrovascular event time (PCET; range: 3-45 days; r-value range -0.926 to 0.857; p<0.05) for ~45,000 CpGs, the vast majority of which became hypomethylated with increasing PCET. Hypomethylation was not due to erasure of the gene-body and CG-poor region hypermethylation that accompany the progression of stable lesions, but rather targeted promoters and CpG islands. Noticeably, promoter hypomethylation and increased expression were observed for genes involved in the inhibition of the inflammatory response, defence against oxidative stress and active DNA demethylation. Our data show that only weak changes in the DNA methylome distinguish symptomatic from asymptomatic carotid plaques, but a widespread demethylation resulting in permissive transcriptional marks at atheroprotective gene promoters is established in plaques after a cerebrovascular event, thus mirroring previous observations that ruptured plaques tend to revert to a more stable structure. The identified loci are candidate targets to accelerate the pace of carotid plaque stabilization. DNA was quantified by Quant-iT PicoGreen dsDNA Reagent (Invitrogen) and the integrity was analyzed in a 1.3% agarose gel. Bisulfite conversion of 600 ng of each sample was perform according to the manufacturer's recommendation for Illumina Infinium Assay. Effective bisulphite conversion was checked for three controls that were converted simultaneously with the samples. 4 ul of bisulfite converted DNA were used to hybridize on Infinium HumanMethylation 450 BeadChip, following Illumina Infinium HD Methylation protocol. Chip analysis was performed using Illumina HiScan SQ fluorescent scanner. The intensities of the images are extracted using GenomeStudio (2011.2) Methylation module (1.8.5) software. Methylation score of each CpG is represented as beta value.

Dataset Information

Low TLR7 gene expression in atherosclerotic plaques is associated with major adverse cardio- and cerebrovascular events.

Publications

Low TLR7 gene expression in atherosclerotic plaques is associated with major adverse cardio- and cerebrovascular events.

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