PCSK9 Confers Inflammatory Properties to Extracellular Vesicles Released by Vascular Smooth Muscle Cells

Abstract

Vascular smooth muscle cells (VSMCs) are key participants in both early- and late-stage atherosclerosis and influence neighbouring cells possibly by means of bioactive molecules, some of which are packed into extracellular vesicles (EVs). Proprotein convertase subtilisin/kexin type 9 (PCSK9) is expressed and secreted by VSMCs. This study aimed to unravel the role of PCSK9 on VSMCs-derived EVs in terms of content and functionality. EVs were isolated from human VSMCs overexpressing human PCSK9 (VSMCPCSK9-EVs) and tested on endothelial cells, monocytes, macrophages and in a model of zebrafish embryos. Compared to EVs released from wild-type VSMCs, VSMCPCSK9-EVs caused a rise in the expression of adhesion molecules in endothelial cells and of pro-inflammatory cytokines in monocytes. These acquired an increased migratory capacity, a reduced oxidative phosphorylation and secreted proteins involved in immune response and immune effector processes. Concerning macrophages, VSMCPCSK9-EVs enhanced inflammatory milieu and uptake of oxidized low-density lipoproteins, whereas the migratory capacity was reduced. When injected into zebrafish embryos, VSMCPCSK9-EVs favoured the recruitment of macrophages toward the site of injection. The results of the present study provide evidence that PCSK9 plays an inflammatory role by means of EVs, at least by those derived from smooth muscle cells of vascular origin.

Lipoprotein(a) in Atherosclerotic Diseases: From Pathophysiology to Diagnosis and Treatment

“…The role of apo-B availability for Lp(a) synthesis is also supported by studies, with antisense oligonucleotides against apo-B synthesis showing parallel Lp(a) reduction [ 257 , 260 ]. Noteworthily, PCSK9i have proven their efficacy by decreasing incidence of acute coronary syndromes and CV deaths in patients with CAD [ 261 ], while, in experimental studies, their interaction with several proinflammatory factors is crucial [ 262 ]. Specifically, Alirocumab reduced the risk of major adverse cardiovascular events by 0.6% for each 1 mg/dL reduction in Lp(a) levels independent of LDL cholesterol reduction [ 261 ].…”

Emerging role of exosomes in vascular diseases

“…Based on unbiased proteomic analysis of EVs derived from VMSCs, EVs released from senescent VSMCs induced secretion of IL-17, interferon-γ (INF-γ) and IL-10 by T cells and tumor necrosis factor-α (TNF-α) by monocytes; moreover, senescent EVs affected the differentiation of monocytes and favored mixed M1/ M2 polarization with proinflammatory characteristics (129). Another study demonstrated that when VSMCs expressed more proprotein convertase subtilisin/kexin type 9 (PCSK9), the released EVs carried a proinflammatory phenotype, which reduced the migratory capacity of macrophages (130). Specifically, exposure to VSMC-EVs resulted in a significant increase in the gene expression of IL-6, VCAM-1, ET-1, ICAM-1 and E-selectin in ECs as well as a significant increase in the gene expression of CCL2 (MCP-1/chemokine (C-C motif) ligand 2), IL-1α, IL-1β, IL-6 and IL-8 in macrophages (130).…”

“…Another study demonstrated that when VSMCs expressed more proprotein convertase subtilisin/kexin type 9 (PCSK9), the released EVs carried a proinflammatory phenotype, which reduced the migratory capacity of macrophages (130). Specifically, exposure to VSMC-EVs resulted in a significant increase in the gene expression of IL-6, VCAM-1, ET-1, ICAM-1 and E-selectin in ECs as well as a significant increase in the gene expression of CCL2 (MCP-1/chemokine (C-C motif) ligand 2), IL-1α, IL-1β, IL-6 and IL-8 in macrophages (130). Activation of ECs occurs during the initiation phase of AS, and understanding the effect of exosomes released from VSMCs on ECs may provide clues for AS treatment.…”

Exploring the role of epicardial adipose-tissue-derived extracellular vesicles in cardiovascular diseases

“… 4 EVs are known to be key players in intercellular communication, given their ability to transport proteins, lipids, and nucleic acids, all of which are reflective of the state of their specific cell of origin. 5 It is well established that EVs are involved in the multiple CVDs, including atherosclerosis, 6 , 7 heart failure, cardiomyopathies, 8 , 9 and atrial fibrillation. 10 Given the difficulties in assessing the paracrine contribution of EAT to CVD, the specific signature carried by EVs derived from EAT may provide an insight on unexplored mechanisms through which this particular tissue may, in part, promote the onset and progression of cardiovascular diseases.…”