A20 inhibits post-angioplasty restenosis by blocking macrophage trafficking and decreasing adventitial neovascularization

Abstract

OBJECTIVE-Neointimal hyperplasia is an inflammatory and proliferative process that occurs as a result of injury to the vessel wall. We have shown that the homeostatic protein A20 prevents neointimal hyperplasia by affecting endothelial cell (EC) and smooth muscle cell (SMC) responses to injury. In this work, we questioned whether A20 impacts other pathogenic effectors of neointimal hyperplasia including homing of monocyte/macrophages and EC/SMC precursors to the site of vascular injury, vascular endothelial growth factor (VEGF) secretion, and adventitial neovascularization.METHODS AND RESULTS-Carotid balloon angioplasty was performed on rat recipients of a bone marrow transplant from green fluorescent rats. Adenoviral delivery of A20 prevented neointimal hyperplasia and decreased macrophage infiltration. This was associated with decreased ICAM-1 and MCP-1 expression in vitro. Additionally, A20 reduced neovascularization in the adventitia of balloon injured carotid arteries, which correlated with fewer VEGF positive cells. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptAtherosclerosis. Author manuscript; available in PMC 2011 August 1. CONCLUSIONS-A20 down-regulates adhesion markers, chemokine production, and adventitial angiogenesis, all of which are required for macrophage trafficking to sites of vascular injury. This, in turn, diminishes the inflammatory milieu to prevent neointimal hyperplasia.

Neointimal hyperplasia in allogeneic and autologous venous grafts is not different in nature

“…A very small percentage of these cells is Ki67 positive (f, arrowhead). (Scale bar 50 µm, magnification ×400) late-stage NH (Damrauer et al 2010). The total number of macrophages in the intima has been found to correlate with the degree of stenosis and was very high in our samples even at 6 months after implantation as shown by KiM1P/ CD68 positivity (Figs.…”

“…The role of chronic inflammation, however, remains unclear, but is not supported by our results. Early infiltrates of CD8-positive T helper cells might be the mainspring, whereas other studies favor VSMC-monocyte interaction (Damrauer et al 2010;Johnson et al 2000;Miller et al 1993). The absence of prominent immune cell infiltrates, but sweepingly the presence of monocytes at least at later points of time, might explain the relative ineffectiveness of immunosuppressive drugs in order to prolong bypass patency further emphasized by the unique morphology of allogen and autologous bypass material (Carpenter and Tomaszewski 1998).…”

A20 Regulates Atherogenic Interferon (IFN)-γ Signaling in Vascular Cells by Modulating Basal IFNβ Levels

“…Those stem from its potent antiinflammatory function in EC and SMC through inhibition of NF-B activation (8,9). They also rely on its NF-B-independent anti-apoptotic, anti-oxidative, and immunomodulatory functions in EC (10 -12) and anti-proliferative and pro-apoptotic (only neointimal SMC) functions in SMC (9,(13)(14)(15). However, the impact of A20 on pro-atherogenic IFN␥ signaling in EC and SMC had never been explored.…”

A20 Haploinsufficiency Aggravates Transplant Arteriosclerosis in Mouse Vascular Allografts

“…Heightened NF-κB activation in SMC is also involved in their phenotypic switch from contractile to synthetic and proliferative(44–46). Inhibiting SMC proliferation is therefore a sound therapeutic strategy to counteract TA, and we had convincingly reported that overexpression of A20 inhibits SMC proliferation both in vitro(9), and in rodent models of IH, including TA(5, 9, 16, 47, 48). Conversely, our data indicate that A20 knockdown in allografts associates with a significant increase in the proliferation rate of SMC.…”

“…For immunohistochemistry (IHC) analysis, frozen sections were incubated with antibodies to VCAM-1, ICAM-1, CD4, CD8 (BD Biosciences, San Jose, CA), NK cells (R&D Systems Inc. Minneapolis, MN) and Ki-67 (ThermoFisher, Tewksubury, MA) followed by biotinylated secondary antibodies (Vector, Burlingame, CA)(16). Adventitial CD4, CD8, and NK positive cells were scored by cell counting using Image J, and expressed as cell number per vessel section.…”