Skip to main content
PMC home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2015 Jan 15.
Published in final edited form as: Discov Med. 2014 May;17(95):233–246.

Current siRNA Targets in Atherosclerosis and Aortic Aneurysm

Leena Pradhan-Nabzdyk 1, Chenyu Huang 1, Frank W Logerfo 1, Christoph S Nabzdyk 1
PMCID: PMC4295203  NIHMSID: NIHMS645674  PMID: 24882715

Abstract

Atherosclerosis (ATH) and aortic aneurysms (AA) remain challenging chronic diseases that confer high morbidity and mortality despite advances in medical, interventional, and surgical care. RNA interference represents a promising technology that may be utilized to silence genes contributing to ATH and AA. Despite positive results in preclinical and some clinical feasibility studies, challenges such as target/sequence validation, tissue specificity, transfection efficiency, and mitigation of unwanted off-target effects remain to be addressed. In this review the most current targets and some novel approaches in siRNA delivery are being discussed. Due to the plethora of investigated targets, only studies published between 2010 and 2014 were included.

Introduction

Cardiovascular diseases such as atherosclerosis (ATH) and aortic aneurysms (AA) remain associated with high morbidity and mortality. Novel molecular therapies need to be investigated to more effectively treat or prevent these conditions. Small interfering RNA (siRNA) is a member of the non-coding RNA family, which includes ribosomal RNA, transfer RNA, microRNA, and several others. Since its discovery, siRNA rapidly permeated the world of science, finding its place in laboratories as a tool for diagnostic or therapeutic nonviral gene silencing (Dorsett and Tuschl, 2004; Elbashir et al., 2001; Zamore et al., 2000). First human clinical trials showed safety and efficacy of therapeutic siRNA delivery for the treatment of amyloidosis and liver cancer (Coelho et al., 2013; Tabernero et al., 2013).

However, siRNA target choice, off-target effects, and tissue/cell specific delivery still represent significant challenges that need to be addressed in order to optimize study outcomes.

Previously in the Prevent III trial, oligodeoxyribonucleotides that are chemically different from siRNA were used to repress cycle regulator elongation factor 2 (E2F) mRNA in human vein grafts. This large trial failed despite promising preclinical data and emphasized how crucial target choice is for the success of non-viral, nucleotide based gene therapy (Conte et al., 2006). Given cellular signaling redundancy it might be necessary to silence multiple genes simultaneously and/or sequentially to achieve clinically detectable effects.

In this review, ATH and AA specific studies investigating siRNA targets were summarized (see also Tables 1 and 2). While in the majority of the listed studies in which siRNA was used as a possible therapeutic tool, some studies were included, in which siRNA was used for diagnostic purposes. Given the plethora of siRNA literature pertaining to vascular disease, especially ATH, the role of microRNA (miRNA) will be discussed at a different time, as it would exceed the scope of this review.

Table 1.

siRNA Targets in Atherosclerosis.

Target Name Mechanism Study Type References
IMMUNE MODULATOR
Toll-like receptors 2 and 4 (TLR2 and 4) inflammation modulation via nuclear factor- kappaB, chemokine secretion and MAPK signaling in vitro Ji et al., 2011; Ji et al., 2010; Geng et al., 2010; Su et al., 2011; Liu et al., 2010; Meng et al., 2013
Mammalian Target of Rapamycin (mTOR) foam cell formation, LDL receptor, chemokine and MMP-2 expression in vitro & mouse model Yu et al., 2011; Ma et al., 2013a; Wang et al., 2013b
C-C chemokine receptor type 2 CCR2 monocyte chemotaxis mouse model Leuschner et al., 2011; Majmudar et al., 2013)
Chemokine (C-X3-C motif) Receptor 1 (CX3CR1) inflammation (TNF-alpha) and remodeling (MMP-9), EC to dendritic cell interaction in vitro Butoi et al., 2011; Liu et al., 2011
C-X-C chemokine receptor type 7 (CXCR7) inflammation, chemotaxis (sdf-1) in vitro Ma et al., 2013b)
Endoplasmic Reticulum (ER) Stress Transducers (protein kinase RNA-like endoplasmic reticulum kinase (PERK) and inositol-requiring protein 1 (IRE-1) inflammation, leukocyte adhesion (ICAM-1, P-Selectin) in vitro Luo et al., 2013; Yao et al., 2013; Moreno et al., 2013
S100 alarmin S100A9 neutrophil activity, macrophage vesicle calcification, SMC differentiation in vitro New et al., 2013; Inaba et al., 2009
LIPID METABOLISM
Oxidized low-density lipoprotein receptor 1 (LOX-1) oxLDL internalization and degradation in vitro Wang et al., 2013a; Zhang et al., 2013b
Apolipoprotein B (apoB) lipoprotein shuttling mouse model Tadin-Strapps et al., 2011)
REACTIVE OXYGEN SPECIES
NADPH oxidase 1 (Nox1), NADPH oxidase, EF-hand calcium binding domain 5 (Nox5) leukocyte adhesion, chemokine ligand expression in vitro Gray et al., 2013; Bayat et al., 2012; Rius et al., 2013
TRANSCRIPTION FACTORS
Nuclear factor-kappaB (NF-κB) Il-17 induced VCAM expression in VSMC in vitro Zhang et al., 2013a
Kruppel Like Factor 4 (KLF4) SMC differentiation (Myocd) in vitro Turner et al., 2013
MATRIX METALLOPROTEINASES (MMPs)
Matrix metalloproteinase 2 and 9 (MMP−2/−9) ECM remodeling, migration, apoptosis in vitro Johnson et al., 2011; Kim et al., 2012; Kowluru et al., 2011
PROTEIN KINASES
Extracellular signal-regulated kinases 1/2 (ERK1/2) proinflammatory cytokines, cell adhesion molecules, oxLDL uptake, proliferation in vitro Li et al., 2010
C-Jun IL-6 and RANKL signaling in vitro Zhang et al., 2012; Kim et al., 2010
c-Jun NH2-terminal kinases (JNK, JNK2) serum amyloid A signaling, EC alignment, NF-kB signaling, SMC migration and pro- liferation in vitro Dong et al., 2011; Wang et al., 2011; Hahn et al., 2011; Wang et al., 2011; Shyu et al., 2012
p38 mitogen-activated protein kinase family (p38 MAPK) LDL accumulation in macrophages, PPAR- gamma expression in vitro Mei et al., 2012
Protein kinase C (PKC) - (PKCα/β/δ) SMC adhesion, migration, CD36 expres- sion, proinflammatory cytokines (IL-1, TNF-alpha, MCP-1, IL-6), apoptosis in vitro Jialal & Devaraj, 2012; Jialal et al., 2013a; Jialal et al., 2013b; Karunakaran et al., 2013; Larroque-Cardoso et al., 2013
Janus kinase/Signal Transducer and Activator of Transcription (JAK/STAT) cholesterol flux in macrophages in vitro Mo et al., 2011; Park et al., 2013b
CELL SURFACE MOLECULES/MEMBRANE RECEPTORS/MEMBRANE ASSOCIATED PRO TEINS
Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1 or CD31) and Fibronectin (FN) VCAM-1 expression, NF-kB signaling in vitro Wang et al., 2011; Feaver et al., 2010
Eph receptors Ephrin A2 (EphA2) and Ephrin A4 (EphA4) VCAM-1 expression; monocyte adhesion, EC stress fiber formation in vitro Funk et al., 2012; Jellinghaus et al., 2013
Caveolin (Cav-1) cholesterol flux in macrophages, macrophage differentiation. ICAM expression, proinflammatory cytokine (IL-1beta), EC tube formation in vitro Hu et al., 2010; Fu et al., 2012; Jagielska et al., 2012
Open in a new tab

Table 2.

siRNA Targets in Aortic Aneurysm.

Target Name Mechanism Study Type Reference
IMMUNE MODULATOR
Toll-like receptors 2 and 4 (TLR2 and 4) vascular remodeling via MMP-2 and −9 in vitro Cheng et al., 2011
C-C chemokine receptor type 2 CCR2 monocyte chemotaxis mouse model de Waard et al., 2010
S100 alarmin S100A4 SMC proliferation; remodeling via MMP in vitro Cao et al., 2013
REACTIVE OXYGEN SPECIES
NADPH oxidase 4 (Nox4) adventitial fibroblast activation in vitro Liu et al., 2012b
TRANSCRIPTION FACTORS
Kruppel Like Factor 4 (KLF4) SMC differentiation in vitro Salmon et al., 2013
MATRIX METALLOPROTEINASES (MMPs)
MMP-2 SMC invasion in vitro Kimura et al., 2010
MMP−9/−12 SMC proliferation in vitro Dwivedi et al., 2009
PROTEIN KINASES
Extracellular signal-regulated kinases 1/2 (ERK1/2) MMP-2 formation in vitro Ghosh et al., 2012
c-Jun NH2-terminal kinases (JNK, JNK2) MMP activity in vitro DiMusto et al., 2012
Protein kinase B (AKT) MMP−2/−9 expression and secretion in vitro Ghosh et al., 2014
Open in a new tab

Methods

Combined PubMed searches that included the words atherosclerosis and siRNA or aortic aneurysm and siRNA were performed. Given the expansive literature on atherosclerosis and siRNA, and partial redundancy, only articles published between 2010 and 2014 were considered for this review. Since pathophysiology of AA shows some key similarities to ATH, we have also included target genes relevant in AA.

Atherosclerosis (ATH)

Atherosclerosis is the most common of the cardiovascular diseases contributing to major morbidity and mortality in the developed world. Several contributing factors including inflammation, endothelial dysfunction, dyslipidemia, diabetes, and hypertension contribute to the development of atherosclerosis. The ultimate manifestation of atherosclerosis that results in plaque development and blockade of blood vessels by recruitment of macrophages, foam cell formation, production of reactive oxygen species, smooth muscle proliferation, and extracellular matrix modulation has been extensively studied including therapies to prevent these events and processes. The number of siRNA-based studies that are aimed to curtail the development of atherosclerosis by targeting the contributing factors and co-morbidities has gone up exponentially and the literature is expanding with an ever-increasing library of potential targets. In the present review, we have included the most recently tested siRNA targets for the treatment and/or prevention of atherosclerosis and cataloged them according to the main pathophysiologic effect or cellular function that they are involved in. Naturally there will be overlap between the individual categories.

Aortic aneurysm (AA)

Aortic aneurysmal disease shares significant pathologic similarities with atherosclerosis. However, enzymatic degradation of the elastic laminae and extracellular matrix (ECM) of the arterial wall is an additional pathognomonic feature that leads to the characteristic weakening and dilation of the aorta. Atherosclerosis, uncontrolled hypertension, trauma, infection, and certain genetic diseases affecting elastin and collagen metabolism are considered etiologies of AA. Conservative management therefore includes medical management of hypertension and hypercholesterolemia, but also the antibiotic doxycycline is being evaluated for its efficacy in treating AA (Petrinec et al., 1996; Thompson et al., 1999; 1998).

In order to better understand the morphologic changes of the affected arteries, extensive molecular analyses have been conducted. Of particular interest has been the role of matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of matrix metalloproteinases (TIMP); MMPs are known to degrade ECM and a dysbalance of MMPs and TIMPs with a shift towards greater MMP activity is believed to contribute to the pathophysiology of arterial aneurysms (Davis et al., 1998; Newman et al., 1994a; 1994b; Palombo et al., 1999; Thompson et al., 1999; Thompson and Baxter, 1999). In this review siRNA experiments targeting MMPs and other potential targets deemed relevant for AA formation were included.

Immune Mediators

Immune mediators that lead to the inflammatory milieu contributing to the pathophysiology of ATH and AA are widely investigated. Following are key targets that were silenced with siRNAs in order to yield a more favorable inflammatory signaling pattern and mitigate ATH and AA.

Toll-like receptor (TLR)

Toll-like receptors are cell membrane pattern recognition receptors involved in the innate immune system and found on macrophages, dendritic, and other cells.

The activation of TLR4 by lipopolysaccharide (LPS) can create an inflammatory milieu that promotes the development of atherosclerosis and diabetes. TLR4 is involved in macrophage foam cell formation, which is a key step in atherosclerotic plaque pathology. TLR4 silencing in vascular smooth muscle cells (VSMC) revealed that effects of anti-inflammatory drugs such as fenofibrate, a Peroxisome proliferator-activated receptor-alpha (PPAR)-α agonist and rosiglitazone, a PPAR-gamma (PPAR-γ) agonist on LPS-mediated inflammation in VSMCs were dependent on TLR4 (Ji et al., 2011; 2010). Plasmid mediated TLR4 silencing in U937 pre-monocytes decreased nuclear factor-kappaB (NF-κB) activity, the secretions of monocyte chemoattractant protein-1 (MCP-1) and the chemokine interleukin-8 (IL-8) in response to oxidized low density lipoprotein (ox-LDL). NF-κB, MCP-1, and IL-8 are all known inflammatory mediators contributing to a myriad of diseases (Geng et al., 2010). Bone morphogenetic protein-2 (BMP-2) plays an important role in atherosclerotic vascular calcification. TLR2 and TLR4 silencing reduced oxidized Low Density Lipoprotein (oxLDL)-induced BMP-2 expression in human coronary artery endothelial cells (HCAEC) (Su et al., 2011). C-reactive protein (CRP) may induce inflammatory responses leading to ATH via a TLR4-dependent signaling pathway, Angiotensin II Type I receptor-p38 mitogen-activated protein kinase-TLR4-Protein Kinase C-alpha (AT-1R-p38 MAPK-TLR4-PKCalpha) in VSMC. TLR4 silencing reversed these pro-inflammatory effects of CRP (Liu et al., 2010). Dysregulated expression of matrix metalloproteinases (MMPs) are known to play a role in various cardiovascular diseases including ATH and AA. TLR2 and TLR4 silencing reduced MMP-2 and MMP-9 gene expression in mouse aortic EC (Cheng et al., 2011).

Mast cells can infiltrate into the atheromatous plaque and secrete various pro-inflammatory cytokines. TLR4 silencing in cultured human mast cells mitigated ox-LDL mediated upregulation of TLR4 and MCP-1, as well as Tumor Necrosis Factor-alpha (TNF-α) and IL-6 secretion. Moreover, TLR4 silencing attenuated ox-LDL stimulated nuclear translocation of NF-κB, and MAPK phosphorylation (Meng et al., 2013).

TLR4 mRNAs often contain AU-rich elements (AREs) in their 3′-untranslated regions (3′UTR), which have a high affinity for RNA-binding proteins such as human antigen R (HuR) that regulate TLR4 expression in human aortic smooth muscle cells (HASMCs). Knockdown of HuR inhibited LPS-induced TLR4 mRNA stability in HASMCs (Lin et al., 2006).

Mammalian Target of Rapamycin (mTOR)

The mammalian target of rapamycin (mTOR) is an intracellular regulator of multiple cellular functions including mitosis, migration, and differentiation (Wang et al., 2013b).

ATH: mTOR has been believed to be involved in the development of atherosclerotic plaques. mTOR silencing in mice decreased macrophage presence and inhibited the progression of atherosclerotic plaques along with decreasing expression of plaque instability. Silencing of mTOR further decreased expression of MMP2, MCP-1, and tissue factor (TF) (Wang et al., 2013b). Inflammation disrupts low-density lipoprotein receptor (LDLr) pathway feedback regulation through the activation of the mTOR pathway in atherosclerosis. Inhibition of the mTOR pathway by mTOR siRNA prevented foam cell formation in vitro and decreased levels of LDLr, in lipopolysaccharide stimulated VSMC (Ma et al., 2013a). Silencing of mTOR and its associated proteins rictor and raptor, inhibited the upregulation of TLR4 expression. Further, inhibition of ox-LDL induced mTOR activation reduced TLR4 expression, and improved the impaired lipid efflux (Yu et al., 2011).

Chemokine receptors

Increased chemokine receptor expression is known to occur in almost all cardiovascular diseases. Immune cell trafficking, a major process involved in ATH and AA, is regulated by the expression of chemokine receptors not only on immune cells but also on vascular cells. Following chemokine receptors were targeted for siRNA therapy or diagnostics.

C-C chemokine receptor type 2 (CCR2)

CCR2 is the receptor for MCP-1 that itself is involved monocyte chemotaxis.

ATH: Inflammatory monocytes but not the non-inflammatory subset depend on the chemokine receptor CCR2 for localization to injured tissue. CCR2 siRNA carrying nanoparticles administered systemically in mice, localized to monocytes, and were rapidly cleared from the blood. CCR2 silencing in monocytes prevented their accumulation in sites of inflammation in mice after myocardial infarction (Leuschner et al., 2011; Majmudar et al., 2013).

AA: CCR2 is also involved in AA formation. siRNA-induced inhibition of CCR2 in leukocytes inhibited aneurysm formation in mice with disruption of the MCP-1/CCR2 signaling pathway (de Waard et al., 2010).

Chemokine (C-X3-C motif) receptor 1 (CX3CR1)

ATH: The chemokine receptor CX3CR1 is expressed in blood monocytes, dendritic cells (DC), and SMC and is associated with atherosclerotic plaque pathology (Landsman et al., 2009; Liu et al., 2011). CX3CR1 and its ligand fractalkine (CX3CL1) are believed to mediate anchorage and chemotaxis between macrophages and SMCs. The interaction of LPS-activated monocytes with SMC increased the expression of TNF-α, MMP-9, and CX3CR1 in both cell types. CX3CR1 knockdown before cell-cell interaction significantly decreased TNF-α, MMP-9, and CX3CR1 upregulation (Butoi et al., 2011). Separately, CX3CR1 silencing has shown an inhibition of interactions between DC and EC (Liu et al., 2011).

C-X-C chemokine receptor type 7 (CXCR7)

While CXCR7 is not expressed in normal blood leukocytes, its role in leukocytes in disease states is not fully understood (Ma et al., 2013b). CXCR7 is considered a new receptor for stromal cell-derived factor-1 (SDF-1). SDF-1 is known to induce leukocyte chemotaxis including macrophages.

ATH: CXCR7 was expressed in macrophage positive areas of aortic atheromas of apolipoprotein E (ApoE)-null mice. Expression was more in M1 macrophages than in the M2 phenotype. CXCR7 was associated with an SDF-1 mediated pro-inflammatory signaling. CXCR7 silencing suppressed macrophage phagocytic activity (Ma et al., 2013b).

Endoplasmic reticulum (ER) stress transducers protein kinase RNA-like endoplasmic reticulum kinase (PERK) and inositol-requiring protein 1 (IRE-1)

PERK inhibits translation in response to ER stress and the protein kinase IRE1 is involved in the response to ER based stress signals.

ATH: The high mobility group 1B protein (HMGB1) mediated chronic inflammatory responses in EC is critical for development of atherosclerosis. HMGB1 induced a dose-dependent activation of ER stress transducers (PERK and IRE-1) in EC. PERK or IRE1 silencing suppressed HMGB1-mediated intercellular cell adhesion molecule-1 (ICAM-1) and P-selectin (Luo et al., 2013). PERK-silencing in RAW264.7 macrophages inhibited ox-LDL-induced apoptosis (Yao et al., 2013).

MCP-1 secretion was increased by TNF-like weak inducer of apoptosis (TWEAK) increased in a cell line derived from human acute monocytic leukemia cells. This could be blocked by HMGB1 silencing (Moreno et al., 2013).

SI00 alarmins S100A9 and S100A4

S100A4, a member of the S100 calcium-binding protein family with a role in cancer cell metastasis, is highly expressed in synthetic SMC, while it is barely detectable in contractile SMC (Boye and Maelandsmo, 2010; Brisset et al., 2007). S100A9 is secreted by neutrophils and monocytes/macrophages and has been linked to cardiovascular disease (Cotoi et al., 2014). S100A9 stimulates neutrophil activity and promotes phagocytosis (Simard et al., 2011).

ATH: The periodontal pathogen, Porphyromonas gingivalis, is involved in atherosclerosis and aortic intimal hyperplasia. S100A9 was upregulated in aortic SMC in response to P. gingivalis. Exposure of aortic SMC to the supernatant of plasma incubated with P. gingivalis induced a proliferative phenotype, which could be attenuated by S100A9 silencing (Inaba et al., 2009). Plaque calcification is linked to macrophage accumulation. Silencing of S100A9 in vitro reduced macrophage matrix vesicle calcification (New et al., 2013).

AA: S100A4 is found in the aortic wall in human thoracic aortic aneurysms. S100A4 silencing decreased VSMC proliferation and MMP-2 and MMP-9 expression (Cao et al., 2013).

Lipid Metabolism Signaling

Liver X receptor alpha (LXRalpha)

LXRalpha belongs to a nuclear receptor superfamily that controls macrophage function, including lipid homeostasis and inflammation (Chawla et al., 2001).

ATH: TLR2 ligand Pam(3)CSK(4) mediated TLR2 activation led to upregulation of ATP binding cassette transporter (ABCA1), a membrane bound regulator of cholesterol efflux in macrophages (Park et al., 2013a). For a while there has been a controversy whether ABCA1 promotes or protects against atherosclerosis. Recent studies suggest that lower ABCA1 levels are associated with increased plaque burden (Bochem et al., 2013; Liu et al., 2012a).

Oxidized low-density lipoprotein receptor 1 (LOX-1)

LOX-1 internalizes and degrades ox-LDL and may have a role as scavenger receptor involved in Fas-induced apoptosis.

ATH: Stretch stress and ox-LDL could each induce activation of extracellular related kinase (ERK) 1/2 and Ki-67 in VSMCs. Knockdown of LOX-1 inhibited these effects (Zhang et al., 2013b). In EC Angiotensin II (AngII) treatment induced inflammation, as indicated by upregulation of VCAM-1, MCP-1, and activation of NF-κB and LOX-1. LOX-1 silencing decreased AngII-induced VCAM-1 production (Wang et al., 2013a).

Apolipoprotein B (apoB)

apoB is the main apolipoprotein of chylomicrons and LDL and is involved in lipoprotein shuttling throughout the body to the tissues.

ATH: Increased serum apoB and associated LDL levels are associated with an increased risk of coronary disease. apoB silencing in mice showed lipid-lowering effects for over three weeks (Tadin-Strapps et al., 2011). Liver specific apoB100 silencing could be achieved by conjugation of siRNA to tocopherol (Makinen and Yla-Herttuala, 2013; Nishina et al., 2008).

Reactive Oxygen Species (Ros)

NADPH oxidase 1 (Nox1), NADPH oxidase, EF-hand calcium binding domain 5 (Nox5), and Nox4

NADPH oxidases (Nox1, Nox3, Nox4, Nox5) are membrane bound enzymes involved in the generation of radical oxygen species and therefore implicated in cardiovascular disease.

ATH: Hyperglycemia induced Nox1 in EC. Nox1 silencing in EC decreased hyperglycemia induced MCP-1, VCAM-1, connective tissue growth factor (CTGF), collagen IV, and fibronectin expression (Gray et al., 2013). Nox1 silencing in VSMC prevented thromboxane A(2) mimetic U46619 mediated increase of IL-1beta-induced monocyte adhesion (Bayat et al., 2012). TNF-α and Nox-5 silencing inhibited AngII induced human umbilical arterial and venous EC chemokine CX(3)CL1 expression (Rius et al., 2013).

AA: Hyperhomocysteinemia (HHcy) has been linked to the formation of abdominal aortic aneurysm (AAA). HHcy increased AngII-mediated AAA formation in apoE-deficient mice. HHcy promoted adventitial fibroblasts transformation into myofibroblasts, increased aortic adventitial inflammation and IL-6 and MCP-1 secretion. Adventitial fibroblast activation was ameliorated by Nox4 silencing (Liu et al., 2012b).

Transcription Factors

Nuclear factor-kappaB (NF-κB)

NF-κB is a DNA transcription regulating protein complex and powerful modulator of inflammation that plays a role in injury response and vascular diseases.

ATH: Interleukin-17 induced NF-κB dependent VCAM-1 expression in VSMC, which could be abrogated by NF-κB silencing (Zhang et al., 2013a).

Kruppel like factor 4 (KLF4)

The transcription factor KLF4 is expressed in EC and in inflamed SMC that mediates inflammatory responses after vascular injury. KLF4 is also a regulator of macrophage activation and believed to be involved in SMC phenotype switching (Yan et al., 2008).

ATH: Phenotypic switching of SMC from contractile to secretory plays a central role in atherosclerosis and restenosis. Human myocardin (Myocd) is the master gene regulator of SMC differentiation. The upstream repressor region PrmM is localized within the Myocd promoter. Klf4 significantly decreased Myocd mRNA, while Klf4 silencing abolished PDGF-BB-mediated repression of PrmM-directed gene expression in SMC (Turner et al., 2013).

AA: Aortic KLF4 expression progressively increased in response to elastase perfusion in C57BL/6 mice. Loss of a KLF4 allele conferred protection from aneurysm formation. KLF4 silencing attenuated downregulation of SM marker gene expression in vitro (Salmon et al., 2013).

ATH: Silencing of the transcriptional regulator EGR-1 ameliorated hyperglycemia induced expression of CD11c, chemokine (C-C motif) ligand 2, and inter-leukin-1beta in U937 macrophages (Kong et al., 2013).

Matrix Metalloproteinases (MMPs)

Activation of matrix metalloproteinases (MMPs) and their isoforms leads to ECM remodeling, which facilitates VSMC invasion, a key event in cardiovascular disease development. Protein kinase B (Akt) is a potent upstream regulator of MMP expression, which will be discussed later in the review.

ATH: MMP-2 and MMP-9 silencing suppressed VSMC migration in an in vitro study of atherosclerosis (Johnson et al., 2011; Kim et al., 2012). MMP-9 silencing in EC provided cell protective effects through decreasing high glucose-induced damage to the mitochondria and chaperone proteins (Kowluru et al., 2011).

AA: MMP-2 activity is regulated by the intrinsic tissue inhibitor of MMP-2 (TIMP-2). MMP-2 silencing decreased SMC invasion, but not proliferation, adhesion, or migration (Kimura et al., 2010). Silencing of MMP-9 and −12 in VSMC decreased beta-catenin signaling and proliferation possibly via a cyclin D1 involving mechanism (Dwivedi et al., 2009).

Protein Kinases

Extracellular signal-regulated kinases 1/2 (ERK1/2)

Extracellular signal-regulated kinases are members of the mitogen-activated protein kinase (MAPK) family that mediate proliferation and differentiation signals in different cell types.

ATH: The proinflammatory cytokine IFN-gamma is involved in atherosclerosis and its cellular signaling is predominantly transmitted through STAT1. ICAM-1, MCP-1, IP-10, and MIP-1β upregulation by IFN-γ is ERK1/2-dependent. Further, ERK1/2 silencing in macrophages attenuated IFN-γ-induced ox-LDL uptake (Li et al., 2010). Further, ERK1/2 silencing reversed high-glucose induced CTGF mediated proliferation and ECM production in VSMC (Ha et al., 2013).

AA: ERK signaling is relevant for MMP activation during AAA formation. ERK1/2 silencing in elastase treated murine VSMC reduced MMP2 formation (Ghosh et al., 2012).

c-Jun

c-Jun is a component of the AP-1 signaling pathway and involved cell cycle regulation and cell differentiation.

ATH: Interleukin-6 (IL-6) is a cytokine pivotal for ECM metabolism. IL-6 decreased P4Halpha1, which is required for collagen synthesis, and collagen and SMC contents in atherosclerotic mouse arteries. IL-6 mediated P4Halpha1 downregulation in hASMC occurred via the RAF-MEK1/2-ERK1/2 MAPK pathway. c-Jun silencing in hASMC mitigated IL-6-induced P4Halpha1 downregulation (Zhang et al., 2012). Receptor activator of NF-κB ligand (RANKL) plays a role in the thrombogenicity of atherosclerotic plaques. c-Jun and early growth response protein 1 (Egr-1) silencing in macrophages attenuated RANKL-induced tissue factor (TF) expression. In macrophages RANKL induced TF through AP-1 and Egr-1 via JNK and ERK1/2 pathways (Kim et al., 2010).

c-Jun NH2-terminal kinases (JNK, JNK2)

JNK is a member of the MAPK family involved in cellular stress signaling and gene expression in EC in response to flow alterations (Wang et al., 2011). Ischemia-reperfusion injury induced cell apoptosis is in part mediated by JNK (Xu et al., 2010).

ATH: Serum amyloid A (SAA) upregulated pentraxin 3 (PTX3), a part of the innate immunity via formyl peptide receptor-like 1 (FPRL1), which overall enhanced proinflammatory processes. SAA induced PTX3 production was attenuated by JNK silencing (Dong et al., 2011). The ability of EC to align in the direction of flow has shown to correlate with protection from atherosclerosis in these regions. JNK2 silencing in EC inhibited alignment in response to shear stress (Hahn et al., 2011). Interestingly, JNK silencing in EC under low shear stress attenuated NF-κB activity and VCAM-1 expression (Wang et al., 2011).

AngII has shown to raise leptin levels in adipocytes and ROS in VSMC, which in turn promotes atherosclerosis. JNK silencing attenuated AngII-induced leptin and phospho-JNK protein expression and diminished AngII-induced VSMC migration and proliferation (Shyu et al., 2012).

AA: In a mouse model of abdominal AA (AAA) males developed larger AAA compared with females with higher levels of JNK1, proMMP2, and proMMP9. JNK1 or JNK2 silencing in VSMC decreased MMP activity, while combined JNK 1 and 2 silencing diminished all MMP activity in vitro (DiMusto et al., 2012).

p38 mitogen-activated protein kinase family (p38 MAPK)

p38 MAPK are members of the mitogen-activated protein kinase family that respond to stress stimuli and play a role in cell differentiation and apoptosis.

ATH: p38 MAPK is implicated in the development of atherosclerosis. p38 MAPK silencing reduced the LDL-induced cholesterol accumulation in macrophages. LDL cholesterol loading-induced inhibition of autophagy was prevented by p38 MAPK silencing (Mei et al., 2012).

PPARgamma ligands have shown to ameliorate AngII-induced atherosclerotic changes. AngII suppressed PPARgamma expression and activity in VSMC in a TGF-beta1 dependent fashion. TGF-beta1 secretion in response to AngII required ROS mediated EGFR kinase activation. p38 MAPK silencing inhibited both AngII- and TGF-beta1-induced PPARgamma reduction (Subramanian et al., 2012).

Protein kinase B (AKT)

AA: Akt is a serine/threonine protein kinase with several isoforms, which are involved in abnormal vascular remodeling through modulation of apoptosis, proliferation, migration, glucose metabolism, and other functions (Jung et al., 2000).

Akt siRNA decreased proMMP2 and proMMP-9, as well as active MMP-2 secretion from elastase-treated VSMC (Ghosh et al., 2014). Interestingly, male human abdominal AA specimens showed higher ratios of phosphorylated AKT/AKT ratios than those from women, implying that differential levels of Akt phosphorylation may be important in sex differences in abdominal AA (Ghosh et al., 2014).

In contrast, deficiency of isoform Akt2 in mice rendered animals more susceptible to AA formation possibly due to an observed increase in MMP-9 and decrease in TIMP-1 activity. In addition Akt2 and phospho-Akt levels were decreased in human thoracic AA specimen (Shen et al., 2013). These opposing observations illustrate the complexity of Akt biology and may also be partially explained by the differential embryonic composition of the aortic segments investigated.

Protein kinase C (PKC) alpha/beta/delta (PKCα/β/δ)

PKC is a family of protein kinases involved in a variety of cellular functions such as apoptosis and endothelial cell proliferation.

PKCα activation can elicit proangiogenic effects, but also increase endothelial permeability (Harrington et al., 1997; Vandenbroucke St Amant et al., 2012).

PKCβ upregulation has been shown to cause vascular dysfunction, by negatively affecting endothelial barrier function, and decreased Akt mediated eNOS expression in response to insulin (Kong et al., 2013; Naruse et al., 2006; Vuong et al., 1998). PKCβ can accelerate diabetic atherosclerosis in mice by modulating macrophage activity and CD11c expression (Kong et al., 2013).

PKCδ increased VSMC adhesion and migration in response to injury and upregulated expression of cholesterol receptors CD36 and SR-A (Kamiya et al., 2007; Lin et al., 2012).

ATH: CRP treated macrophages showed increased levels of PKCα and PKCδ with subsequent upregulation of IL-1, MCP-1, TNF-alpha, and IL-6. PKCα and PKCδ silencing reversed these effects (Jialal and Devaraj, 2012; Jialal et al., 2013a; 2013b). PKC regulated apoE secretion independent of ABCA1. PKCα/β silencing in macrophages inhibited apoE secretion (Karunakaran et al., 2013). PKCδ elicited pro-apoptotic signals in various cells and has a role in the stress response to ox-LDL. PKCδ silencing in VSMC protected against ox-LDL-induced apoptosis (Larroque-Cardoso et al., 2013).

Janus kinase/signal transducer and activator of transcription (JAK/STAT)

The JAK/STAT system binds to transmembrane receptors and aids in transmitting extracellular signals into the nucleus. Leukocytes show activation of several JAK/STAT pathways, which thus are believed to involve immune functions.

ATH: Advanced oxidation protein products (AOPP) are suspected to promote coronary artery disease. In T-helper-1 (THP-1)-derived foam-like cells, AOPP decreased LXRalpha and ABCA1 via JAK/STAT, which in turn inhibited cholesterol efflux.

JAK/STAT silencing could block these effects of AOPP in THP-1 cells (Mo et al., 2011). Tissue factor (TF) has a central role in the coagulation cascade and is also involved in neointima and atherosclerosis development. JAK2 silencing by siRNA inhibited TLR2 ligand Pam3CSK4 induced TF expression in macrophages. Pam3CSK4 stimulated STAT3 phosphorylation (S727), while STAT3 siRNA reduced Pam3CSK4-induced TF expression (Park et al., 2013b).

Cell Surface Molecules/Membrane Receptors/ Membrane Associated Proteins

Platelet endothelial cell adhesion molecule 1 (PECAM-1) or CD31 and fibronectin (FN)

PECAM-1 or CD31 is a surface antigen found on many cell types such as EC, neutrophils, monocytes, and platelets and is involved in leukocyte migration, angio-genesis, and other cell functions.

FN is a glycoprotein and crucial component linking ECM to cell membrane bound integrins. FN plays central roles in cell differentiation, migration, proliferation, and other functions.

ATH: As discussed earlier, JNK silencing attenuated NF-κB activity and VCAM-1 expression in HUVECs under low shear stress. Furthermore, CD31 siRNA reduced p-JNK and VCAM-1 levels in the setting of low shear stress. In the setting of low shear stress JNK may promote atherosclerosis through a CD31-dependent pathway and by modulating NF-κB and VCAM-1 (Wang et al., 2011).

It was demonstrated that CD31 mediated FN deposition in response to atheroprone flow, which in turn increased NF-κB activity and VCAM1 expression in EC. CD31 silencing in EC blocked FN deposition, decreased NF-κB activation, and lowered VCAM1 expression. Additionally, FN silencing also reduced NF-κB activity, which was reversed by exogenous FN (Feaver et al., 2010).

Ephrin receptors ephrin A2 (EphA2) and ephrin A4 (EphA4)

Eph receptors are cell membrane bound and are activated in response to injury. EphA receptor and EphA ligand expression is induced by various proinflammatory mediators (Funk et al., 2012).

ATH: EphA2 and its ligand EphA1 are highly expressed in EC of atherosclerotic plaques of mice and humans. EphA2 silencing diminished VCAM-1 expression in response to EphA1 and ox-LDL (Funk et al., 2012). In a separate study EphA4 and EphA1 were found in most cells within human atherosclerotic plaques. EphA4 silencing blocked EphA1-induced monocyte adhesion to EC as well as stress fiber formation (Jellinghaus et al., 2013).

Caveolin (Cav-1)

Cav-1 is a component of the plasma membrane caveolae and is involved in macrophage inflammation, adhesion, and phagocytosis and thus is believed to influence the development of IH and atherosclerosis (Fu et al., 2012; Luo et al., 2010).

ATH: Cav-1 silencing reduced cholesterol efflux in macrophages (Hu et al., 2010). Cav-1 promoted monocyte to macrophage differentiation via EGR-1. Cav-1 gain of function in macrophages increased ICAM-1 and CD11b, while Cav-1 silencing reduced these (Fu et al., 2012). Lastly, Cav-1 silencing diminished IL-1beta-induced activation of p38-MAPK and MAPK-activated protein kinase 2 (MK2), as well as EC tube formation in vitro and angiogenesis in vivo (Jagielska et al., 2012).

Delivery

Most standard transfection methods that yield sufficient in vitro transfection success with minimal toxicity cannot be applied for in vivo studies, e.g., due to immune response to viral vectors, toxicity of certain chemicals, or technical limitations as in electroporation. Poly(B-amino ester) polymers, known for their hydrolytic biodegradability, low toxicity, and triggered nucleic acid release, may be an alternative to commercial chemical agents (Arnold et al., 2012). Complicating that, significant differences exist in the efficacy of transfection reagents and in the susceptibility of endothelial cells, smooth muscle cells as well as macrophages towards RNAi (Nabzdyk et al., 2011; 2012).

The mannose receptor CD206 and macrophage/dendriteic cell marker was used to facilitate CD206-targeted RNAi delivery. Compared to control cells these nanoparticles delivered over 13-fold more siRNA into macrophages (Yu et al., 2013).

VCAM-1 and E-Selectin are EC surface molecules upregulated in response to inflammation and play central roles in leukocyte adhesion and transmigration and thus contribute to the development of atherosclerosis. siRNA containing liposomal particles targeting VCAM-1 or E-Selectin have proven to selectively target inflamed endothelium, while not entering quiescent EC. This approach may prove successful for selective therapy of particularly active atherosclerotic lesions (Kowalski et al., 2011; 2013; 2014; Leus et al., 2014).

Local siRNA release from gelatin-PEI-siRNA coated vascular stents achieved significant silencing in EC (Nolte et al., 2011). Similarly, PEI-siRNA complexes released from dip-coated electrospun polyethylene terephthalate bypass graft fabrics silenced target genes in infiltrating VSMC in vitro (Nabzdyk et al., 2014).

Future studies will have to explore customizable delivery methods that allow for highly predictable cell/tissue specific delivery without causing significant off-target or immune responses. Anatomical barriers, diffusion distances, tissue specificity, lysosomal entrapment, controlled and prolonged release as well as hepatic and macrophage clearance are just some key aspects that need to be addressed in the coming years to improve in vivo siRNA therapies.

Discussion

Atherosclerosis and AA are complex, chronic diseases that involve a multitude of pathophysiologic processes, cell types, cytokines, and enzymes and thus a plethora of potential therapeutic targets exists. However, in many of the examples presented in this review, large animal in vivo target evaluation has to be performed to validate these targets for potential clinical trials. Bioinformatics and systems biology may help delineate these complex and often redundant cell signaling networks and identify crucial relay stations and regulators that could be targeted with siRNA.

While siRNA is a powerful technology, it also has significant limitations that need to be addressed in order to maximize effectiveness. siRNA molecules have a very short half-life in vivo and need to be chemically protected from thermal and enzymatic degradation. In addition, in vivo transfection efficiency is a vital determinant of target gene silencing. There is promising research in the field of cell specific siRNA delivery that may ultimately lead to the development of efficacious therapies (Kowalski et al., 2011; 2013; 2014; Leus et al., 2014; Leuschner et al., 2011). This may decrease the amount of siRNA needed and mitigate unwanted off-target effects. siRNA off-target effects due to nonspecific siRNA/mRNA hybridization may incidentally adversely alter cell signaling.

Atherosclerosis is a systemic disease and chronic treatment using systemic administration of siRNA may neither be scientifically feasible nor cost effective. Additionally, the transient effect of siRNA on gene expression needs to be factored into the therapy. Whether repeated siRNA administrations are necessary or if the administration of a single bulk dose of siRNA for instance, encapsulated in nanoparticles in form of a depot is feasible, needs to be evaluated in future studies.

However, siRNA may soon become an adjuvant therapeutic for local application in diseased arterial segments, and/or in conjunction with surgical or interventional therapy. It is conceivable that in the near future siRNAs targeting specific genes may replace more toxic reagents such as sirolimus or tacrolimus in order to prevent restenosis after percutaneous angioplasty and stenting or mitigate intimal hyperplasia after arterial bypass grafting. In recent studies, vascular stents and bypass graft materials were successfully coated with siRNA. Large in vivo studies and clinical trials yet are still missing to validate these approaches (Nabzdyk et al., 2014; Nolte et al., 2011).

After the disappointing results of the PREVENT III trial there has been a concern regarding the usefulness of gene therapy for the treatment of vascular disease. With the advancements in bioinformatics, systems biology, and chemical engineering, gene therapy today is more sophisticated and customizable than ever before (Bhasin et al., 2012; Kowalski et al., 2014; Leuschner et al., 2011). Such a customized interdisciplinary approach may render effective gene therapy for the treatment of atherosclerosis and AA.

Supplementary Material

Supplementary File

Acknowledgments

This work was supported, in part, by grants from the National Institutes of Health (NIH 5R01 HL021796, NIH 2R01 HL086741 and T32 HL007734) and the William J. von Liebig Foundation.

Footnotes

Disclosure

The authors report no conflicts of interest.

References

  1. Arnold JD, Mountain DJ, Freeman MB, Kirkpatrick SS, Stevens SL, Goldman MH, Grandas OH. Smooth muscle cell polymeric transfection is an efficient alternative to traditional methods of experimental gene therapy. J Surg Res. 2012;177(1):178–184. doi: 10.1016/j.jss.2012.05.037. [DOI] [PubMed] [Google Scholar]
  2. Bayat H, Schroder K, Pimentel DR, Brandes RP, Verbeuren TJ, Cohen RA, Jiang B. Activation of thromboxane receptor modulates interleukin-1beta-induced monocyte adhesion–a novel role of Nox1. Free Radic Biol Med. 2012;52(9):1760–1766. doi: 10.1016/j.freeradbiomed.2012.02.052. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bhasin M, Huang Z, Pradhan-Nabzdyk L, Malek JY, Logerfo PJ, Contreras M, Guthrie P, Csizmadia E, Andersen N, Kocher O, Ferran C, Logerfo FW. Temporal network based analysis of cell specific vein graft transcriptome defines key pathways and hub genes in implantation injury. PLoS One. 2012;7(6):e39123. doi: 10.1371/journal.pone.0039123. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Bochem AE, Van Wijk DF, Holleboom AG, Duivenvoorden R, Motazacker MM, Dallinga-Thie GM, De Groot E, Kastelein JJ, Nederveen AJ, Hovingh GK, Stroes ES. ABCA1 mutation carriers with low high-density lipoprotein cholesterol are characterized by a larger atherosclerotic burden. Eur Heart J. 2013;34(4):286–291. doi: 10.1093/eurheartj/ehs376. [DOI] [PubMed] [Google Scholar]
  5. Boye K, Maelandsmo GM. S100A4 and metastasis: a small actor playing many roles. Am J Pathol. 2010;176(2):528–535. doi: 10.2353/ajpath.2010.090526. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Brisset AC, Hao H, Camenzind E, Bacchetta M, Geinoz A, Sanchez JC, Chaponnier C, Gabbiani G, Bochaton-Piallat ML. Intimal smooth muscle cells of porcine and human coronary artery express S100A4, a marker of the rhomboid phenotype in vitro. Circ Res. 2007;100(7):1055–1062. doi: 10.1161/01.RES.0000262654.84810.6c. [DOI] [PubMed] [Google Scholar]
  7. Butoi ED, Gan AM, Manduteanu I, Stan D, Calin M, Pirvulescu M, Koenen RR, Weber C, Simionescu M. Cross talk between smooth muscle cells and monocytes/activated monocytes via CX3CL1/CX3CR1 axis augments expression of pro-atherogenic molecules. Biochim Biophys Acta. 2011;1813(12):2026–2035. doi: 10.1016/j.bbamcr.2011.08.009. [DOI] [PubMed] [Google Scholar]
  8. Cao J, Geng L, Wu Q, Wang W, Chen Q, Lu L, Shen W, Chen Y. Spatiotemporal expression of matrix metalloproteinases (MMPs) is regulated by the Ca2+-signal transducer S100A4 in the pathogenesis of thoracic aortic aneurysm. PLoS One. 2013;8(7):e70057. doi: 10.1371/journal.pone.0070057. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Chawla A, Boisvert WA, Lee CH, Laffitte BA, Barak Y, Joseph SB, Liao D, Nagy L, Edwards PA, Curtiss LK, Evans RM, Tontonoz P. A PPAR gamma-LXR-ABCA1 pathway in macrophages is involved in cholesterol efflux and atherogenesis. Mol Cell. 2001;7(1):161–171. doi: 10.1016/s1097-2765(01)00164-2. [DOI] [PubMed] [Google Scholar]
  10. Cheng XW, Song H, Sasaki T, Hu L, Inoue A, Bando YK, Shi GP, Kuzuya M, Okumura K, Murohara T. Angiotensin type 1 receptor blocker reduces intimal neovascularization and plaque growth in apolipoprotein E-deficient mice. Hypertension. 2011;57(5):981–989. doi: 10.1161/HYPERTENSIONAHA.110.168385. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Coelho T, Adams D, Silva A, Lozeron P, Hawkins PN, Mant T, Perez J, Chiesa J, Warrington S, Tranter E, Munisamy M, Falzone R, Harrop J, Cehelsky J, Bettencourt BR, Geissler M, Butler JS, Sehgal A, Meyers RE, Chen Q, et al. Safety and efficacy of RNAi therapy for transthyretin amyloidosis. N Engl J Med. 2013;369(9):819–829. doi: 10.1056/NEJMoa1208760. [DOI] [PubMed] [Google Scholar]
  12. Conte MS, Bandyk DF, Clowes AW, Moneta GL, Seely L, Lorenz TJ, Namini H, Hamdan AD, Roddy SP, Belkin M, Berceli SA, Demasi RJ, Samson RH, Berman SS, Investigators PI. Results of PREVENT III: a multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery. J Vasc Surg. 2006;43(4):742–751. doi: 10.1016/j.jvs.2005.12.058. discussion 751. [DOI] [PubMed] [Google Scholar]
  13. Cotoi OS, Duner P, Ko N, Hedblad B, Nilsson J, Bjorkbacka H, Schiopu A. Plasma S100A8/A9 correlates with blood neutrophil counts, traditional risk factors, and cardiovascular disease in middle-aged healthy individuals. Arterioscler Thromb Vasc Biol. 2014;34(1):202–210. doi: 10.1161/ATVBAHA.113.302432. [DOI] [PubMed] [Google Scholar]
  14. Davis V, Persidskaia R, Baca-Regen L, Itoh Y, Nagase H, Persidsky Y, Ghorpade A, Baxter BT. Matrix metalloproteinase-2 production and its binding to the matrix are increased in abdominal aortic aneurysms. Arterioscler Thromb Vasc Biol. 1998;18(10):1625–1633. doi: 10.1161/01.atv.18.10.1625. [DOI] [PubMed] [Google Scholar]
  15. De Waard V, Bot I, De Jager SC, Talib S, Egashira K, De Vries MR, Quax PH, Biessen EA, Van Berkel TJ. Systemic MCP1/CCR2 blockade and leukocyte specific MCP1/CCR2 inhibition affect aortic aneurysm formation differently. Atherosclerosis. 2010;211(1):84–89. doi: 10.1016/j.atherosclerosis.2010.01.042. [DOI] [PubMed] [Google Scholar]
  16. Dimusto PD, Lu G, Ghosh A, Roelofs KJ, Sadiq O, Mcevoy B, Su G, Laser A, Bhamidipati CM, Ailawadi G, Henke PK, Eliason JL, Upchurch GR., Jr Increased JNK in males compared with females in a rodent model of abdominal aortic aneurysm. J Surg Res. 2012;176(2):687–695. doi: 10.1016/j.jss.2011.11.1024. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Dong Z, An F, Wu T, Zhang C, Zhang M, Zhang Y, An G, An F. PTX3, a key component of innate immunity, is induced by SAA via FPRL1-mediated signaling in HAECs. J Cell Biochem. 2011;112(8):2097–2105. doi: 10.1002/jcb.23128. [DOI] [PubMed] [Google Scholar]
  18. Dorsett Y, Tuschl T. siRNAs: applications in functional genomics and potential as therapeutics. Nat Rev Drug Discov. 2004;3(4):318–329. doi: 10.1038/nrd1345. [DOI] [PubMed] [Google Scholar]
  19. Dwivedi A, Slater SC, George SJ. MMP-9 and −12 cause N-cadherin shedding and thereby beta-catenin signalling and vascular smooth muscle cell proliferation. Cardiovasc Res. 2009;81(1):178–186. doi: 10.1093/cvr/cvn278. [DOI] [PubMed] [Google Scholar]
  20. Elbashir SM, Harborth J, Lendeckel W, Yalcin A, Weber K, Tuschl T. Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature. 2001;411(6836):494–498. doi: 10.1038/35078107. [DOI] [PubMed] [Google Scholar]
  21. Feaver RE, Gelfand BD, Wang C, Schwartz MA, Blackman BR. Atheroprone hemodynamics regulate fibronectin deposition to create positive feedback that sustains endothelial inflammation. Circ Res. 2010;106(11):1703–1711. doi: 10.1161/CIRCRESAHA.109.216283. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Fu Y, Moore XL, Lee MK, Fernandez-Rojo MA, Parat MO, Parton RG, Meikle PJ, Sviridov D, Chin-Dusting JP. Caveolin-1 plays a critical role in the differentiation of monocytes into macrophages. Arterioscler Thromb Vasc Biol. 2012;32(9):e117–e125. doi: 10.1161/ATVBAHA.112.254151. [DOI] [PubMed] [Google Scholar]
  23. Funk SD, Yurdagul A, Jr, Albert P, Traylor JG, Jr, Jin L, Chen J, Orr AW. EphA2 activation promotes the endothelial cell inflammatory response: a potential role in atherosclerosis. Arterioscler Thromb Vasc Biol. 2012;32(3):686–695. doi: 10.1161/ATVBAHA.111.242792. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Geng H, Wang A, Rong G, Zhu B, Deng Y, Chen J, Zhong R. The effects of ox-LDL in human atherosclerosis may be mediated in part via the toll-like receptor 4 pathway. Mol Cell Biochem. 2010;342(1–2):201–206. doi: 10.1007/s11010-010-0484-8. [DOI] [PubMed] [Google Scholar]
  25. Ghosh A, Dimusto PD, Ehrlichman LK, Sadiq O, Mcevoy B, Futchko JS, Henke PK, Eliason JL, Upchurch GR., Jr The role of extracellular signal-related kinase during abdominal aortic aneurysm formation. J Am Coll Surg. 2012;215(5):668–680. doi: 10.1016/j.jamcollsurg.2012.06.414. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Ghosh A, Lu G, Su G, Mcevoy B, Sadiq O, Dimusto PD, Laser A, Futchko JS, Henke PK, Eliason JL, Upchurch GR., Jr Phosphorylation of AKT and abdominal aortic aneurysm formation. Am J Pathol. 2014;184(1):148–158. doi: 10.1016/j.ajpath.2013.09.016. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Gray SP, Di Marco E, Okabe J, Szyndralewiez C, Heitz F, Montezano AC, De Haan JB, Koulis C, El-Osta A, Andrews KL, Chin-Dusting JP, Touyz RM, Wingler K, Cooper ME, Schmidt HH, Jandeleit-Dahm KA. NADPH oxidase 1 plays a key role in diabetes mellitus-accelerated atherosclerosis. Circulation. 2013;127(18):1888–1902. doi: 10.1161/CIRCULATIONAHA.112.132159. [DOI] [PubMed] [Google Scholar]
  28. Ha YM, Lee DH, Kim M, Kang YJ. High glucose induces connective tissue growth factor expression and extracellular matrix accumulation in rat aorta vascular smooth muscle cells via extracellular signal-regulated kinase 1/2. Korean J Physiol Pharmacol. 2013;17(4):307–314. doi: 10.4196/kjpp.2013.17.4.307. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Hahn C, Wang C, Orr AW, Coon BG, Schwartz MA. JNK2 promotes endothelial cell alignment under flow. PLoS One. 2011;6(8):e24338. doi: 10.1371/journal.pone.0024338. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Harrington EO, Loffler J, Nelson PR, Kent KC, Simons M, Ware JA. Enhancement of migration by protein kinase Calpha and inhibition of proliferation and cell cycle progression by protein kinase Cdelta in capillary endothelial cells. J Biol Chem. 1997;272(11):7390–7397. doi: 10.1074/jbc.272.11.7390. [DOI] [PubMed] [Google Scholar]
  31. Hu Q, Zhang XJ, Liu CX, Wang XP, Zhang Y. PPARgamma1-induced caveolin-1 enhances cholesterol efflux and attenuates atherosclerosis in apolipoprotein E-deficient mice. J Vasc Res. 2010;47(1):69–79. doi: 10.1159/000235927. [DOI] [PubMed] [Google Scholar]
  32. Inaba H, Hokamura K, Nakano K, Nomura R, Katayama K, Nakajima A, Yoshioka H, Taniguchi K, Kamisaki Y, Ooshima T, Umemura K, Murad F, Wada K, Amano A. Upregulation of S100 calcium-binding protein A9 is required for induction of smooth muscle cell proliferation by a periodontal pathogen. FEBS Lett. 2009;583(1):128–134. doi: 10.1016/j.febslet.2008.11.036. [DOI] [PubMed] [Google Scholar]
  33. Jagielska J, Kapopara PR, Salguero G, Scherr M, Schutt H, Grote K, Schieffer B, Bavendiek U. Interleukin-1 assembles a proangiogenic signaling module consisting of caveolin-1, tumor necrosis factor receptor-associated factor 6, p38-mitogen-activated protein kinase (MAPK), and MAPK-activated protein kinase 2 in endothelial cells. Arterioscler Thromb Vasc Biol. 2012;32(5):1280–1288. doi: 10.1161/ATVBAHA.111.243477. [DOI] [PubMed] [Google Scholar]
  34. Jellinghaus S, Poitz DM, Ende G, Augstein A, Weinert S, Stutz B, Braun-Dullaeus RC, Pasquale EB, Strasser RH. Ephrin-A1/EphA4-mediated adhesion of monocytes to endothelial cells. Biochim Biophys Acta. 2013;1833(10):2201–2211. doi: 10.1016/j.bbamcr.2013.05.017. [DOI] [PubMed] [Google Scholar]
  35. Ji Y, Liu J, Wang Z, Li Z. PPARgamma agonist rosiglitazone ameliorates LPS-induced inflammation in vascular smooth muscle cells via the TLR4/TRIF/IRF3/IP-10 signaling pathway. Cytokine. 2011;55(3):409–419. doi: 10.1016/j.cyto.2011.05.020. [DOI] [PubMed] [Google Scholar]
  36. Ji Y, Wang Z, Li Z, Liu J. Modulation of LPS-mediated inflammation by fenofibrate via the TRIF-dependent TLR4 signaling pathway in vascular smooth muscle cells. Cell Physiol Biochem. 2010;25(6):631–640. doi: 10.1159/000315082. [DOI] [PubMed] [Google Scholar]
  37. Jialal I, Devaraj S. Antisense to protein kinase C-alpha and p47phox attenuates the pro-inflammatory effects of human C-reactive protein in macrophages of biobreeding diabetic rats. Diab Vasc Dis Res. 2012;9(4):315–319. doi: 10.1177/1479164112452165. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Jialal I, Kaur H, Devaraj S. Human C-reactive protein accentuates macrophage activity in biobreeding diabetic rats. J Diabetes Complications. 2013a;27(1):23–28. doi: 10.1016/j.jdiacomp.2012.03.020. [DOI] [PMC free article] [PubMed] [Google Scholar]
  39. Jialal I, Machha A, Devaraj S. Small interfering-RNA to protein kinase C-delta reduces the proinflammatory effects of human C-reactive protein in biobreeding diabetic rats. Horm Metab Res. 2013b;45(4):326–328. doi: 10.1055/s-0032-1327643. [DOI] [PubMed] [Google Scholar]
  40. Johnson JL, Dwivedi A, Somerville M, George SJ, Newby AC. Matrix metalloproteinase (MMP)-3 activates MMP-9 mediated vascular smooth muscle cell migration and neointima formation in mice. Arterioscler Thromb Vasc Biol. 2011;31(9):e35–e44. doi: 10.1161/ATVBAHA.111.225623. [DOI] [PubMed] [Google Scholar]
  41. Jung F, Haendeler J, Goebel C, Zeiher AM, Dimmeler S. Growth factor-induced phosphoinositide 3-OH kinase/Akt phosphorylation in smooth muscle cells: induction of cell proliferation and inhibition of cell death. Cardiovasc Res. 2000;48(1):148–157. doi: 10.1016/s0008-6363(00)00152-8. [DOI] [PubMed] [Google Scholar]
  42. Kamiya K, Ryer E, Sakakibara K, Zohlman A, Kent KC, Liu B. Protein kinase C delta activated adhesion regulates vascular smooth muscle cell migration. J Surg Res. 2007;141(1):91–96. doi: 10.1016/j.jss.2007.02.025. [DOI] [PubMed] [Google Scholar]
  43. Karunakaran D, Kockx M, Owen DM, Burnett JR, Jessup W, Kritharides L. Protein kinase C controls vesicular transport and secretion of apolipoprotein E from primary human macrophages. J Biol Chem. 2013;288(7):5186–5197. doi: 10.1074/jbc.M112.428961. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Kim D, Lee D, Jang YL, Chae SY, Choi D, Jeong JH, Kim SH. Facial amphipathic deoxycholic acid-modified polyethyleneimine for efficient MMP-2 siRNA delivery in vascular smooth muscle cells. Eur J Pharm Biopharm. 2012;81(1):14–23. doi: 10.1016/j.ejpb.2012.01.013. [DOI] [PubMed] [Google Scholar]
  45. Kim J, Min JK, Park JA, Doh HJ, Choi YS, Rho J, Kim YM, Kwon YG. Receptor activator of nuclear factor kappaB ligand is a novel inducer of tissue factor in macrophages. Circ Res. 2010;107(7):871–876. doi: 10.1161/CIRCRESAHA.110.221168. [DOI] [PubMed] [Google Scholar]
  46. Kimura K, Cheng XW, Nakamura K, Inoue A, Hu L, Song H, Okumura K, Iguchi A, Murohara T, Kuzuya M. Matrix metalloproteinase-2 regulates the expression of tissue inhibitor of matrix metalloproteinase-2. Clin Exp Pharmacol Physiol. 2010;37(11):1096–1101. doi: 10.1111/j.1440-1681.2010.05441.x. [DOI] [PubMed] [Google Scholar]
  47. Kong L, Shen X, Lin L, Leitges M, Rosario R, Zou YS, Yan SF. PKCbeta promotes vascular inflammation and acceleration of atherosclerosis in diabetic ApoE null mice. Arterioscler Thromb Vasc Biol. 2013;33(8):1779–1787. doi: 10.1161/ATVBAHA.112.301113. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Kowalski PS, Leus NG, Scherphof GL, Ruiters MH, Kamps JA, Molema G. Targeted siRNA delivery to diseased microvascular endothelial cells: cellular and molecular concepts. IUBMB Life. 2011;63(8):648–658. doi: 10.1002/iub.487. [DOI] [PubMed] [Google Scholar]
  49. Kowalski PS, Lintermans LL, Morselt HW, Leus NG, Ruiters MH, Molema G, Kamps JA. Anti-VCAM-1 and anti-E-selectin SAINT-O-Somes for selective delivery of siRNA into inflammation-activated primary endothelial cells. Mol Pharm. 2013;10(8):3033–3044. doi: 10.1021/mp4001124. [DOI] [PubMed] [Google Scholar]
  50. Kowalski PS, Zwiers PJ, Morselt HW, Kuldo JM, Leus NG, Ruiters MH, Molema G, Kamps JA. Anti-VCAM-1 SAINT-O-Somes enable endothelial-specific delivery of siRNA and downregulation of inflammatory genes in activated endothelium in vivo. J Control Release. 2014;176C:64–75. doi: 10.1016/j.jconrel.2013.12.029. [DOI] [PubMed] [Google Scholar]
  51. Kowluru RA, Mohammad G, Dos Santos JM, Zhong Q. Abrogation of MMP-9 gene protects against the development of retinopathy in diabetic mice by preventing mitochondrial damage. Diabetes. 2011;60(11):3023–3033. doi: 10.2337/db11-0816. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Landsman L, Bar-On L, Zernecke A, Kim KW, Krauthgamer R, Shagdarsuren E, Lira SA, Weissman IL, Weber C, Jung S. CX3CR1 is required for monocyte homeostasis and atherogenesis by promoting cell survival. Blood. 2009;113(4):963–972. doi: 10.1182/blood-2008-07-170787. [DOI] [PubMed] [Google Scholar]
  53. Larroque-Cardoso P, Swiader A, Ingueneau C, Negre-Salvayre A, Elbaz M, Reyland ME, Salvayre R, Vindis C. Role of protein kinase C delta in ER stress and apoptosis induced by oxidized LDL in human vascular smooth muscle cells. Cell Death Dis. 2013;4:e520. doi: 10.1038/cddis.2013.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Leus NG, Talman EG, Ramana P, Kowalski PS, Woudenberg-Vrenken TE, Ruiters MH, Molema G, Kamps JA. Effective siRNA delivery to inflamed primary vascular endothelial cells by anti-E-selectin and anti-VCAM-1 PEGylated SAINT-based lipoplexes. Int J Pharm. 2014;459(1–2):40–50. doi: 10.1016/j.ijpharm.2013.11.008. [DOI] [PubMed] [Google Scholar]
  55. Leuschner F, Dutta P, Gorbatov R, Novobrantseva TI, Donahoe JS, Courties G, Lee KM, Kim JI, Markmann JF, Marinelli B, Panizzi P, Lee WW, Iwamoto Y, Milstein S, Epstein-Barash H, Cantley W, Wong J, Cortez-Retamozo V, Newton A, Love K, et al. Therapeutic siRNA silencing in inflammatory monocytes in mice. Nat Biotechnol. 2011;29(11):1005–1010. doi: 10.1038/nbt.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Li N, Mclaren JE, Michael DR, Clement M, Fielding CA, Ramji DP. ERK is integral to the IFN-gamma-mediated activation of STAT1, the expression of key genes implicated in atherosclerosis, and the uptake of modified lipoproteins by human macrophages. J Immunol. 2010;185(5):3041–3048. doi: 10.4049/jimmunol.1000993. [DOI] [PubMed] [Google Scholar]
  57. Lin CS, Lin FY, Ho LJ, Tsai CS, Cheng SM, Wu WL, Huang CY, Lian CH, Yang SP, Lai JH. PKCdelta signalling regulates SR-A and CD36 expression and foam cell formation. Cardiovasc Res. 2012;95(3):346–355. doi: 10.1093/cvr/cvs189. [DOI] [PubMed] [Google Scholar]
  58. Lin FY, Chen YH, Lin YW, Tsai JS, Chen JW, Wang HJ, Chen YL, Li CY, Lin SJ. The role of human antigen R, an RNA-binding protein, in mediating the stabilization of toll-like receptor 4 mRNA induced by endotoxin: a novel mechanism involved in vascular inflammation. Arterioscler Thromb Vasc Biol. 2006;26(12):2622–2629. doi: 10.1161/01.ATV.0000246779.78003.cf. [DOI] [PubMed] [Google Scholar]
  59. Liu HF, Cui KF, Wang JP, Zhang M, Guo YP, Li XY, Jiang C. Significance of ABCA1 in human carotid atherosclerotic plaques. Exp Ther Med. 2012a;4(2):297–302. doi: 10.3892/etm.2012.576. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Liu N, Liu J, Ji Y, Lu P. Toll-like receptor 4 signaling mediates inflammatory activation induced by C-reactive protein in vascular smooth muscle cells. Cell Physiol Biochem. 2010;25(4–5):467–476. doi: 10.1159/000303052. [DOI] [PubMed] [Google Scholar]
  61. Liu X, Lu G, Shen J. Silencing CX3CR1 production modulates the interaction between dendritic and endothelial cells. Mol Biol Rep. 2011;38(1):481–488. doi: 10.1007/s11033-010-0131-1. [DOI] [PubMed] [Google Scholar]
  62. Liu Z, Luo H, Zhang L, Huang Y, Liu B, Ma K, Feng J, Xie J, Zheng J, Hu J, Zhan S, Zhu Y, Xu Q, Kong W, Wang X. Hyperhomocysteinemia exaggerates adventitial inflammation and angiotensin II-induced abdominal aortic aneurysm in mice. Circ Res. 2012b;111(10):1261–1273. doi: 10.1161/CIRCRESAHA.112.270520. [DOI] [PubMed] [Google Scholar]
  63. Luo DX, Cheng J, Xiong Y, Li J, Xia C, Xu C, Wang C, Zhu B, Hu Z, Liao DF. Static pressure drives proliferation of vascular smooth muscle cells via caveolin-1/ERK1/2 pathway. Biochem Biophys Res Commun. 2010;391(4):1693–1697. doi: 10.1016/j.bbrc.2009.12.132. [DOI] [PubMed] [Google Scholar]
  64. Luo Y, Li SJ, Yang J, Qiu YZ, Chen FP. HMGB1 induces an inflammatory response in endothelial cells via the RAGE-dependent endoplasmic reticulum stress pathway. Biochem Biophys Res Commun. 2013;438(4):732–738. doi: 10.1016/j.bbrc.2013.07.098. [DOI] [PubMed] [Google Scholar]
  65. Ma KL, Liu J, Wang CX, Ni J, Zhang Y, Wu Y, Lv LL, Ruan XZ, Liu BC. Activation of mTOR modulates SREBP-2 to induce foam cell formation through increased retinoblastoma protein phosphorylation. Cardiovasc Res. 2013a;100(3):450–460. doi: 10.1093/cvr/cvt203. [DOI] [PubMed] [Google Scholar]
  66. Ma W, Liu Y, Ellison N, Shen J. Induction of C-X-C chemokine receptor type 7 (CXCR7) switches stromal cell-derived factor-1 (SDF-1) signaling and phagocytic activity in macrophages linked to atherosclerosis. J Biol Chem. 2013b;288(22):15481–15494. doi: 10.1074/jbc.M112.445510. [DOI] [PMC free article] [PubMed] [Google Scholar]
  67. Majmudar MD, Keliher EJ, Heidt T, Leuschner F, Truelove J, Sena BF, Gorbatov R, Iwamoto Y, Dutta P, Wojtkiewicz G, Courties G, Sebas M, Borodovsky A, Fitzgerald K, Nolte MW, Dickneite G, Chen JW, Anderson DG, Swirski FK, Weissleder R, et al. Monocyte-directed RNAi targeting CCR2 improves infarct healing in atherosclerosis-prone mice. Circulation. 2013;127(20):2038–2046. doi: 10.1161/CIRCULATIONAHA.112.000116. [DOI] [PMC free article] [PubMed] [Google Scholar]
  68. Makinen PI, Yla-Herttuala S. Therapeutic gene targeting approaches for the treatment of dyslipidemias and atherosclerosis. Curr Opin Lipidol. 2013;24(2):116–122. doi: 10.1097/MOL.0b013e32835da13c. [DOI] [PubMed] [Google Scholar]
  69. Mei S, Gu H, Ward A, Yang X, Guo H, He K, Liu Z, Cao W. p38 mitogen-activated protein kinase (MAPK) promotes cholesterol ester accumulation in macrophages through inhibition of macroautophagy. J Biol Chem. 2012;287(15):11761–11768. doi: 10.1074/jbc.M111.333575. [DOI] [PMC free article] [PubMed] [Google Scholar]
  70. Meng Z, Yan C, Deng Q, Dong X, Duan ZM, Gao DF, Niu XL. Oxidized low-density lipoprotein induces inflammatory responses in cultured human mast cells via Toll-like receptor 4. Cell Physiol Biochem. 2013;31(6):842–853. doi: 10.1159/000350102. [DOI] [PubMed] [Google Scholar]
  71. Mo ZC, Xiao J, Liu XH, Hu YW, Li XX, Yi GH, Wang Z, Tang YL, Liao DF, Tang CK. AOPPs inhibits cholesterol efflux by down-regulating ABCA1 expression in a JAK/STAT signaling pathway-dependent manner. J Atheroscler Thromb. 2011;18(9):796–807. doi: 10.5551/jat.6569. [DOI] [PubMed] [Google Scholar]
  72. Moreno JA, Sastre C, Madrigal-Matute J, Munoz-Garcia B, Ortega L, Burkly LC, Egido J, Martin-Ventura JL, Blanco-Colio LM. HMGB1 expression and secretion are increased via TWEAK-Fn14 interaction in atherosclerotic plaques and cultured monocytes. Arterioscler Thromb Vasc Biol. 2013;33(3):612–620. doi: 10.1161/ATVBAHA.112.300874. [DOI] [PubMed] [Google Scholar]
  73. Nabzdyk CS, Chun M, Pradhan L, Logerfo FW. High throughput RNAi assay optimization using adherent cell cytometry. J Transl Med. 2011;9:48. doi: 10.1186/1479-5876-9-48. [DOI] [PMC free article] [PubMed] [Google Scholar]
  74. Nabzdyk CS, Chun M, Pradhan Nabzdyk L, Yoshida S, Logerfo FW. Differential susceptibility of human primary aortic and coronary artery vascular cells to RNA interference. Biochem Biophys Res Commun. 2012;425(2):261–265. doi: 10.1016/j.bbrc.2012.07.078. [DOI] [PMC free article] [PubMed] [Google Scholar]
  75. Nabzdyk CS, Chun MC, Oliver-Allen HS, Pathan SG, Phaneuf MD, You JO, Pradhan-Nabzdyk LK, Logerfo FW. Gene silencing in human aortic smooth muscle cells induced by PEI-siRNA complexes released from dip-coated electrospun poly(ethylene terephtha-late) grafts. Biomaterials. 2014;35(9):3071–3079. doi: 10.1016/j.biomaterials.2013.12.026. [DOI] [PMC free article] [PubMed] [Google Scholar]
  76. Naruse K, Rask-Madsen C, Takahara N, Ha SW, Suzuma K, Way KJ, Jacobs JR, Clermont AC, Ueki K, Ohshiro Y, Zhang J, Goldfine AB, King GL. Activation of vascular protein kinase C-beta inhibits Akt-dependent endothelial nitric oxide synthase function in obesity-associated insulin resistance. Diabetes. 2006;55(3):691–698. doi: 10.2337/diabetes.55.03.06.db05-0771. [DOI] [PubMed] [Google Scholar]
  77. New SE, Goettsch C, Aikawa M, Marchini JF, Shibasaki M, Yabusaki K, Libby P, Shanahan CM, Croce K, Aikawa E. Macrophage-derived matrix vesicles: an alternative novel mechanism for microcalcification in atherosclerotic plaques. Circ Res. 2013;113(1):72–77. doi: 10.1161/CIRCRESAHA.113.301036. [DOI] [PMC free article] [PubMed] [Google Scholar]
  78. Newman KM, Malon AM, Shin RD, Scholes JV, Ramey WG, Tilson MD. Matrix metalloproteinases in abdominal aortic aneurysm: characterization, purification, and their possible sources. Connect Tissue Res. 1994a;30(4):265–276. doi: 10.3109/03008209409015042. [DOI] [PubMed] [Google Scholar]
  79. Newman KM, Ogata Y, Malon AM, Irizarry E, Gandhi RH, Nagase H, Tilson MD. Identification of matrix metalloproteinases 3 (stromelysin-1) and 9 (gelatinase B) in abdominal aortic aneurysm. Arterioscler Thromb. 1994b;14(8):1315–1320. doi: 10.1161/01.atv.14.8.1315. [DOI] [PubMed] [Google Scholar]
  80. Nishina K, Unno T, Uno Y, Kubodera T, Kanouchi T, Mizusawa H, Yokota T. Efficient in vivo delivery of siRNA to the liver by conjugation of alpha-tocopherol. Mol Ther. 2008;16(4):734–740. doi: 10.1038/mt.2008.14. [DOI] [PubMed] [Google Scholar]
  81. Nolte A, Walker T, Schneider M, Kray O, Avci-Adali M, Ziemer G, Wendel HP. Small-interfering RNA-eluting surfaces as a novel concept for intravascular local gene silencing. Mol Med. 2011;17(11–12):1213–1222. doi: 10.2119/molmed.2011.00143. [DOI] [PMC free article] [PubMed] [Google Scholar]
  82. Palombo D, Maione M, Cifiello BI, Udini M, Maggio D, Lupo M. Matrix metalloproteinases. Their role in degenerative chronic diseases of abdominal aorta. J Cardiovasc Surg (Torino) 1999;40(2):257–260. [PubMed] [Google Scholar]
  83. Park DW, Lee HK, Lyu JH, Chin H, Kang SW, Kim YJ, Bae YS, Baek SH. TLR2 stimulates ABCA1 expression via PKC-eta and PLD2 pathway. Biochem Biophys Res Commun. 2013a;430(3):933–937. doi: 10.1016/j.bbrc.2012.11.135. [DOI] [PubMed] [Google Scholar]
  84. Park DW, Lyu JH, Kim JS, Chin H, Bae YS, Baek SH. Role of JAK2-STAT3 in TLR2-mediated tissue factor expression. J Cell Biochem. 2013b;114(6):1315–1321. doi: 10.1002/jcb.24472. [DOI] [PubMed] [Google Scholar]
  85. Petrinec D, Liao S, Holmes DR, Reilly JM, Parks WC, Thompson RW. Doxycycline inhibition of aneurysmal degeneration in an elastase-induced rat model of abdominal aortic aneurysm: preservation of aortic elastin associated with suppressed production of 92 kD gelatinase. J Vasc Surg. 1996;23(2):336–346. doi: 10.1016/s0741-5214(96)70279-3. [DOI] [PubMed] [Google Scholar]
  86. Rius C, Piqueras L, Gonzalez-Navarro H, Albertos F, Company C, Lopez-Gines C, Ludwig A, Blanes JI, Morcillo EJ, Sanz MJ. Arterial and venous endothelia display differential functional fractalkine (CX3CL1) expression by angiotensin-II. Arterioscler Thromb Vasc Biol. 2013;33(1):96–104. doi: 10.1161/ATVBAHA.112.254870. [DOI] [PubMed] [Google Scholar]
  87. Salmon M, Johnston WF, Woo A, Pope NH, Su G, Upchurch GR, Jr, Owens GK, Ailawadi G. KLF4 regulates abdominal aortic aneurysm morphology and deletion attenuates aneurysm formation. Circulation. 2013;128(11 Suppl 1):S163–S174. doi: 10.1161/CIRCULATIONAHA.112.000238. [DOI] [PMC free article] [PubMed] [Google Scholar]
  88. Shen YH, Zhang L, Ren P, Nguyen MT, Zou S, Wu D, Wang XL, Coselli JS, Lemaire SA. AKT2 confers protection against aortic aneurysms and dissections. Circ Res. 2013;112(4):618–632. doi: 10.1161/CIRCRESAHA.112.300735. [DOI] [PMC free article] [PubMed] [Google Scholar]
  89. Shyu KG, Chen SC, Wang BW, Cheng WP, Hung HF. Mechanism of the inhibitory effect of atorvastatin on leptin expression induced by angiotensin II in cultured human coronary artery smooth muscle cells. Clin Sci (Lond) 2012;122(1):33–42. doi: 10.1042/CS20110114. [DOI] [PubMed] [Google Scholar]
  90. Simard JC, Simon MM, Tessier PA, Girard D. Damage-associated molecular pattern S100A9 increases bactericidal activity of human neutrophils by enhancing phagocytosis. J Immunol. 2011;186(6):3622–3631. doi: 10.4049/jimmunol.1002956. [DOI] [PubMed] [Google Scholar]
  91. Su X, Ao L, Shi Y, Johnson TR, Fullerton DA, Meng X. Oxidized low density lipoprotein induces bone morphogenetic protein-2 in coronary artery endothelial cells via Toll-like receptors 2 and 4. J Biol Chem. 2011;286(14):12213–12220. doi: 10.1074/jbc.M110.214619. [DOI] [PMC free article] [PubMed] [Google Scholar]
  92. Subramanian V, Golledge J, Heywood EB, Bruemmer D, Daugherty A. Regulation of peroxisome proliferator-activated receptor-gamma by angiotensin II via transforming growth factor-beta1-activated p38 mitogen-activated protein kinase in aortic smooth muscle cells. Arterioscler Thromb Vasc Biol. 2012;32(2):397–405. doi: 10.1161/ATVBAHA.111.239897. [DOI] [PMC free article] [PubMed] [Google Scholar]
  93. Tabernero J, Shapiro GI, Lorusso PM, Cervantes A, Schwartz GK, Weiss GJ, Paz-Ares L, Cho DC, Infante JR, Alsina M, Gounder MM, Falzone R, Harrop J, White AC, Toudjarska I, Bumcrot D, Meyers RE, Hinkle G, Svrzikapa N, Hutabarat RM, et al. First-in-humans trial of an RNA interference therapeutic targeting VEGF and KSP in cancer patients with liver involvement. Cancer Discov. 2013;3(4):406–417. doi: 10.1158/2159-8290.CD-12-0429. [DOI] [PubMed] [Google Scholar]
  94. Tadin-Strapps M, Peterson LB, Cumiskey AM, Rosa RL, Mendoza VH, Castro-Perez J, Puig O, Zhang L, Strapps WR, Yendluri S, Andrews L, Pickering V, Rice J, Luo L, Chen Z, Tep S, Ason B, Somers EP, Sachs AB, Bartz SR, et al. siRNA-induced liver ApoB knockdown lowers serum LDL-cholesterol in a mouse model with human-like serum lipids. J Lipid Res. 2011;52(6):1084–1097. doi: 10.1194/jlr.M012872. [DOI] [PMC free article] [PubMed] [Google Scholar]
  95. Thompson MM, Boyle JR, Crowther M, Goodall S, Wills A, Loftus IM, Bell PR. Therapeutic options in small abdominal aneurysms: the role of in vitro studies. Ann N Y Acad Sci. 1999;878:724–727. doi: 10.1111/j.1749-6632.1999.tb07773.x. [DOI] [PubMed] [Google Scholar]
  96. Thompson RW, Baxter BT. MMP inhibition in abdominal aortic aneurysms. Rationale for a prospective randomized clinical trial. Ann N Y Acad Sci. 1999;878:159–178. doi: 10.1111/j.1749-6632.1999.tb07682.x. [DOI] [PubMed] [Google Scholar]
  97. Thompson RW, Liao S, Curci JA. Therapeutic potential of tetracycline derivatives to suppress the growth of abdominal aortic aneurysms. Adv Dent Res. 1998;12(2):159–165. doi: 10.1177/08959374980120011301. [DOI] [PubMed] [Google Scholar]
  98. Turner EC, Huang CL, Govindarajan K, Caplice NM. Identification of a Klf4-dependent upstream repressor region mediating transcriptional regulation of the myocardin gene in human smooth muscle cells. Biochim Biophys Acta. 2013;1829(11):1191–1201. doi: 10.1016/j.bbagrm.2013.09.002. [DOI] [PubMed] [Google Scholar]
  99. Vandenbroucke St Amant E, Tauseef M, Vogel SM, Gao XP, Mehta D, Komarova YA, Malik AB. PKCalpha activation of p120-catenin serine 879 phospho-switch disassembles VE-cadherin junctions and disrupts vascular integrity. Circ Res. 2012;111(6):739–749. doi: 10.1161/CIRCRESAHA.112.269654. [DOI] [PMC free article] [PubMed] [Google Scholar]
  100. Vuong PT, Malik AB, Nagpala PG, Lum H. Protein kinase C beta modulates thrombin-induced Ca2+ signaling and endothelial permeability increase. J Cell Physiol. 1998;175(3):379–387. doi: 10.1002/(SICI)1097-4652(199806)175:3<379::AID-JCP16>3.0.CO;2-0. [DOI] [PubMed] [Google Scholar]
  101. Wang J, An FS, Zhang W, Gong L, Wei SJ, Qin WD, Wang XP, Zhao YX, Zhang Y, Zhang C, Zhang MX. Inhibition of c-Jun N-terminal kinase attenuates low shear stress-induced atherogenesis in apolipoprotein E-deficient mice. Mol Med. 2011;17(9–10):990–999. doi: 10.2119/molmed.2011.00073. [DOI] [PMC free article] [PubMed] [Google Scholar]
  102. Wang L, Hu X, Zhang W, Tian F. Angiotensin (1–7) ameliorates angiotensin II-induced inflammation by inhibiting LOX-1 expression. Inflamm Res. 2013a;62(2):219–228. doi: 10.1007/s00011-012-0571-2. [DOI] [PubMed] [Google Scholar]
  103. Wang X, Li L, Li M, Dang X, Wan L, Wang N, Bi X, Gu C, Qiu S, Niu X, Zhu X, Wang L. Knockdown of mTOR by lentivirusmediated RNA interference suppresses atherosclerosis and stabilizes plaques via a decrease of macrophages by autophagy in apolipoprotein Edeficient mice. Int J Mol Med. 2013b;32(5):1215–1221. doi: 10.3892/ijmm.2013.1494. [DOI] [PubMed] [Google Scholar]
  104. Xu B, Zhou Y, O K, Choy PC, Pierce GN, Siow YL. Regulation of stress-associated scaffold proteins JIP1 and JIP3 on the c-Jun NH2-terminal kinase in ischemia-reperfusion. Can J Physiol Pharmacol. 2010;88(11):1084–1092. doi: 10.1139/y10-088. [DOI] [PubMed] [Google Scholar]
  105. Yan FF, Liu YF, Liu Y, Zhao YX. KLF4: a novel target for the treatment of atherosclerosis. Med Hypotheses. 2008;70(4):845–847. doi: 10.1016/j.mehy.2007.07.031. [DOI] [PubMed] [Google Scholar]
  106. Yao S, Zong C, Zhang Y, Sang H, Yang M, Jiao P, Fang Y, Yang N, Song G, Qin S. Activating transcription factor 6 mediates oxidized LDL-induced cholesterol accumulation and apoptosis in macrophages by up-regulating CHOP expression. J Atheroscler Thromb. 2013;20(1):94–107. doi: 10.5551/jat.13425. [DOI] [PubMed] [Google Scholar]
  107. Yu M, Kang X, Xue H, Yin H. Toll-like receptor 4 is up-regulated by mTOR activation during THP-1 macrophage foam cells formation. Acta Biochim Biophys Sin (Shanghai) 2011;43(12):940–947. doi: 10.1093/abbs/gmr093. [DOI] [PubMed] [Google Scholar]
  108. Yu SS, Lau CM, Barham WJ, Onishko HM, Nelson CE, Li H, Smith CA, Yull FE, Duvall CL, Giorgio TD. Macrophage-specific RNA interference targeting via “click”, mannosylated polymeric micelles. Mol Pharm. 2013;10(3):975–987. doi: 10.1021/mp300434e. [DOI] [PMC free article] [PubMed] [Google Scholar]
  109. Zamore PD, Tuschl T, Sharp PA, Bartel DP. RNAi: double-stranded RNA directs the ATP-dependent cleavage of mRNA at 21 to 23 nucleotide intervals. Cell. 2000;101(1):25–33. doi: 10.1016/S0092-8674(00)80620-0. [DOI] [PubMed] [Google Scholar]
  110. Zhang H, Chen J, Liu X, Awar L, Mcmickle A, Bai F, Nagarajan S, Yu S. IL-17 induces expression of vascular cell adhesion molecule through signalling pathway of NF-kappaB, but not Akt1 and TAK1 in vascular smooth muscle cells. Scand J Immunol. 2013a;77(4):230–237. doi: 10.1111/sji.12030. [DOI] [PMC free article] [PubMed] [Google Scholar]
  111. Zhang K, Huang XZ, Li XN, Feng M, Li L, Cai XJ, Zhang C, Liu XL, Zhang MX, Zhang Y, Wang XL, Zhang M. Interleukin 6 destabilizes atherosclerotic plaques by downregulating prolyl-4-hydroxylase alpha1 via a mitogen-activated protein kinase and c-Jun pathway. Arch Biochem Biophys. 2012;528(2):127–133. doi: 10.1016/j.abb.2012.09.007. [DOI] [PubMed] [Google Scholar]
  112. Zhang Z, Zhang M, Li Y, Liu S, Ping S, Wang J, Ning F, Xie F, Li C. Simvastatin inhibits the additive activation of ERK1/2 and proliferation of rat vascular smooth muscle cells induced by combined mechanical stress and oxLDL through LOX-1 pathway. Cell Signal. 2013b;25(1):332–340. doi: 10.1016/j.cellsig.2012.10.006. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary File
NIHMS645674-supplement-Supplementary_File.pdf (505.1KB, pdf)

RESOURCES