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- Artiach, G, et al.
(author)
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Proteoglycan 4 is Increased in Human Calcified Aortic Valves and Enhances Valvular Interstitial Cell Calcification
- 2020
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In: Cells. - : MDPI AG. - 2073-4409. ; 9:3
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Journal article (peer-reviewed)abstract
- Aortic valve stenosis (AVS), a consequence of increased fibrosis and calcification of the aortic valve leaflets, causes progressive narrowing of the aortic valve. Proteoglycans, structural components of the aortic valve, accumulate in regions with fibrosis and moderate calcification. Particularly, proteoglycan 4 (PRG4) has been identified in fibrotic parts of aortic valves. However, the role of PRG4 in the context of AVS and aortic valve calcification has not yet been determined. Here, transcriptomics, histology, and immunohistochemistry were performed in human aortic valves from patients undergoing aortic valve replacement. Human valve interstitial cells (VICs) were used for calcification experiments and RNA expression analysis. PRG4 was significantly upregulated in thickened and calcified regions of aortic valves compared with healthy regions. In addition, mRNA levels of PRG4 positively associated with mRNA for proteins involved in cardiovascular calcification. Treatment of VICs with recombinant human PRG4 enhanced phosphate-induced calcification and increased the mRNA expression of bone morphogenetic protein 2 and the runt-related transcription factor 2. In summary, PRG4 was upregulated in the development of AVS and promoted VIC osteogenic differentiation and calcification. These results suggest that an altered valve leaflet proteoglycan composition may play a role in the progression of AVS.
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- Gallina, AL, et al.
(author)
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AMPA-Type Glutamate Receptors Associated With Vascular Smooth Muscle Cell Subpopulations in Atherosclerosis and Vascular Injury
- 2021
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In: Frontiers in cardiovascular medicine. - : Frontiers Media SA. - 2297-055X. ; 8, s. 655869-
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Journal article (peer-reviewed)abstract
- Objectives and Aims: Vascular smooth muscle cells (VSMCs) are key constituents of both normal arteries and atherosclerotic plaques. They have an ability to adapt to changes in the local environment by undergoing phenotypic modulation. An improved understanding of the mechanisms that regulate VSMC phenotypic changes may provide insights that suggest new therapeutic targets in treatment of cardiovascular disease (CVD). The amino-acid glutamate has been associated with CVD risk and VSMCs metabolism in experimental models, and glutamate receptors regulate VSMC biology and promote pulmonary vascular remodeling. However, glutamate-signaling in human atherosclerosis has not been explored.Methods and Results: We identified glutamate receptors and glutamate metabolism-related enzymes in VSMCs from human atherosclerotic lesions, as determined by single cell RNA sequencing and microarray analysis. Expression of the receptor subunits glutamate receptor, ionotropic, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPA)-type subunit 1 (GRIA1) and 2 (GRIA2) was restricted to cells of mesenchymal origin, primarily VSMCs, as confirmed by immunostaining. In a rat model of arterial injury and repair, changes of GRIA1 and GRIA2 mRNA level were most pronounced at time points associated with VSMC proliferation, migration, and phenotypic modulation. In vitro, human carotid artery SMCs expressed GRIA1, and selective AMPA-type receptor blocking inhibited expression of typical contractile markers and promoted pathways associated with VSMC phenotypic modulation. In our biobank of human carotid endarterectomies, low expression of AMPA-type receptor subunits was associated with higher content of inflammatory cells and a higher frequency of adverse clinical events such as stroke.Conclusion: AMPA-type glutamate receptors are expressed in VSMCs and are associated with phenotypic modulation. Patients suffering from adverse clinical events showed significantly lower mRNA level of GRIA1 and GRIA2 in their atherosclerotic lesions compared to asymptomatic patients. These results warrant further mapping of neurotransmitter signaling in the pathogenesis of human atherosclerosis.
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- Seime, T, et al.
(author)
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Proteoglycan 4 Modulates Osteogenic Smooth Muscle Cell Differentiation during Vascular Remodeling and Intimal Calcification
- 2021
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In: Cells. - : MDPI AG. - 2073-4409. ; 10:6
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Journal article (peer-reviewed)abstract
- Calcification is a prominent feature of late-stage atherosclerosis, but the mechanisms driving this process are unclear. Using a biobank of carotid endarterectomies, we recently showed that Proteoglycan 4 (PRG4) is a key molecular signature of calcified plaques, expressed in smooth muscle cell (SMC) rich regions. Here, we aimed to unravel the PRG4 role in vascular remodeling and intimal calcification. PRG4 expression in human carotid endarterectomies correlated with calcification assessed by preoperative computed tomographies. PRG4 localized to SMCs in early intimal thickening, while in advanced lesions it was found in the extracellular matrix, surrounding macro-calcifications. In experimental models, Prg4 was upregulated in SMCs from partially ligated ApoE−/− mice and rat carotid intimal hyperplasia, correlating with osteogenic markers and TGFb1. Furthermore, PRG4 was enriched in cells positive for chondrogenic marker SOX9 and around plaque calcifications in ApoE−/− mice on warfarin. In vitro, PRG4 was induced in SMCs by IFNg, TGFb1 and calcifying medium, while SMC markers were repressed under calcifying conditions. Silencing experiments showed that PRG4 expression was driven by transcription factors SMAD3 and SOX9. Functionally, the addition of recombinant human PRG4 increased ectopic SMC calcification, while arresting cell migration and proliferation. Mechanistically, it suppressed endogenous PRG4, SMAD3 and SOX9, and restored SMC markers’ expression. PRG4 modulates SMC function and osteogenic phenotype during intimal remodeling and macro-calcification in response to TGFb1 signaling, SMAD3 and SOX9 activation. The effects of PRG4 on SMC phenotype and calcification suggest its role in atherosclerotic plaque stability, warranting further investigations.
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