Differential cell cycle progression patterns of infiltrating leukocytes and resident cells after balloon injury of the rat carotid artery

Smooth Muscle Cell Phenotypic Switch Induced by Traditional Cigarette Smoke Condensate: A Holistic Overview

Cigarette smoke (CS) is a risk factor for inflammatory diseases, such as atherosclerosis. CS condensate (CSC) contains lipophilic components that may represent a systemic cardiac risk factor. To better understand CSC effects, we incubated mouse and human aortic smooth muscle cells (SMCs) with CSC. We evaluated specific markers for contractile [i.e., actin, aortic smooth muscle (ACTA2), calponin-1 (CNN1), the Kruppel-like factor 4 (KLF4), and myocardin (MYOCD) genes] and inflammatory [i.e., IL-1β, and IL-6, IL-8, and galectin-3 (LGALS-3) genes] phenotypes. CSC increased the expression of inflammatory markers and reduced the contractile ones in both cell types, with KLF4 modulating the SMC phenotypic switch. Next, we performed a mass spectrometry-based differential proteomic approach on human SMCs and could show 11 proteins were significantly affected by exposition to CSC (FC ≥ 2.7, p ≤ 0.05). These proteins are active in signaling pathways related to expression of pro-inflammatory cytokines and IFN, inflammasome assembly and activation, cytoskeleton regulation and SMC contraction, mitochondrial integrity and cellular response to oxidative stress, proteostasis control via ubiquitination, and cell proliferation and epithelial-to-mesenchymal transition. Through specific bioinformatics resources, we showed their tight functional correlation in a close interaction niche mainly orchestrated by the interferon-induced double-stranded RNA-activated protein kinase (alternative name: protein kinase RNA-activated; PKR) (EIF2AK2/PKR). Finally, by combining gene expression and protein abundance data we obtained a hybrid network showing reciprocal integration of the CSC-deregulated factors and indicating KLF4 and PKR as the most relevant factors.

Inflammatory Cell Dynamics after Murine Femoral Artery Wire Injury: A Multi-Parameter Flow Cytometry-Based Analysis

An acute inflammatory response following arterial surgery for atherosclerosis, such as balloon angioplasty, stenting, and surgical bypass, is an important driver of neointimal hyperplasia after arterial injury, which leads to recurrent ischemia. However, a comprehensive understanding of the dynamics of the inflammatory infiltrate in the remodeling artery is difficult to attain due to the shortcomings of conventional methods such as immunofluorescence. We developed a 15-parameter flow cytometry method to quantitate leukocytes and 13 leukocyte subtypes in murine arteries at 4 time points after femoral artery wire injury. Live leukocyte numbers peaked at 7 days, which preceded the peak neointimal hyperplasia lesion at 28 days. Neutrophils were the most abundant early infiltrate, followed by monocytes and macrophages. Eosinophils were elevated after 1 day, while natural killer and dendritic cells gradually infiltrated over the first 7 days; all decreased between 7 and 14 days. Lymphocytes began accumulating at 3 days and peaked at 7 days. Immunofluorescence of arterial sections demonstrated similar temporal trends of CD45+ and F4/80+ cells. This method allows for the simultaneous quantitation of multiple leukocyte subtypes from small tissue samples of injured murine arteries and identifies the CD64+Tim4+ macrophage phenotype as being potentially important in the first 7 days post-injury.

Synthetic E-selectin prevents postoperative vascular restenosis by inhibiting nuclear factor κB in rats

During the development of postoperative vascular restenosis, the aberrant proliferation of vascular smooth muscle cells (VSMCs) is a critical event resulting in intimal hyperplasia. Inflammatory responses involving the activation of nuclear factor (NF)-κB are among the major molecular processes underlying restenosis. The present study aimed to investigate the roles of NF-κB in VSMC proliferation and restenosis following vascular anastomosis, as well as to evaluate the potential of synthetic E-selectin to downregulate NF-κB and thus inhibit vascular hyperplasia. A total of 72 adult male Sprague-Dawley rats were randomly assigned to three groups: Control, operation and treatment groups. Rats in the operation and treatment groups received longitudinal incisions in the right carotid arteries, which were closed using interrupted sutures. Following vascular anastomosis, synthetic E-selectin (10 mg/kg), or an equal volume of saline, was immediately injected into the right femoral vein of rats in the treatment and operation groups, respectively. Following surgery, the mRNA and protein expression levels of NF-κB at the site of anastomosis, the levels of tumor necrosis factor-α and interleukin-6 in the serum, NF-κB binding activity, and the presence of proliferating cell nuclear antigen (PCNA)-positive cells were evaluated by western blotting, reverse transcription-quantitative polymerase chain reaction, ELISA, electrophoretic mobility shift assay and immunofluorescence staining. The present results demonstrated that following treatment with synthetic E-selectin, the levels of NF-κB and the inflammatory response, as well as the presence of PCNA-positive cells, were significantly reduced (P<0.01). In conclusion, the results of the present study suggested that synthetic E-selectin may exert anti-inflammatory and anti-restenotic effects following vascular anastomosis in vivo.

Platelet CD40 Mediates Leukocyte Recruitment and Neointima Formation after Arterial Denudation Injury in Atherosclerosis-Prone Mice

The role of platelets in the development of thrombosis and abrupt closure after angioplasty is well recognized. However, the direct impact of platelets on neointima formation after arterial injury remains undetermined. Herein, we show that neointima formation after carotid artery wire injury reduces markedly in CD40-/- apolipoprotein E-deficient (apoE-/-) mice but only slightly in CD40 ligand-/-apoE-/- mice, compared with apoE-/- mice. Wild-type and CD40-deficient platelets were isolated from blood of apoE-/- and CD40-/-apoE-/- mice, respectively. The i.v. injection of thrombin-activated platelets into CD40-/-apoE-/- mice was performed every 5 days, starting at 2 days before wire injury. Injection of wild-type platelets promoted neointima formation, which was associated with increased inflammation by stimulating leukocyte recruitment via up-regulation of circulating platelet surface P-selectin expression and the formation of platelet-leukocyte aggregates. It was also associated with further promoting the luminal deposition of platelet-derived regulated on activation normal T cell expressed and secreted/chemokine (C-C motif) ligand 5 and expression of monocyte chemoattractant protein-1 and vascular cell adhesion molecule 1 in wire-injured carotid arteries. Remarkably, all these inflammatory actions by activated platelets were abrogated by lack of CD40 on injected platelets. Moreover, injection of wild-type platelets inhibited endothelial recovery in wire-injured carotid arteries, but this effect was also abrogated by lack of CD40 on injected platelets. Results suggest that platelet CD40 plays a pivotal role in neointima formation after arterial injury and might represent an attractive target to prevent restenosis after vascular interventions.

Inhibition of p110δ PI3K prevents inflammatory response and restenosis after artery injury

Inflammatory cells play key roles in restenosis upon vascular surgical procedures such as bypass grafts, angioplasty and stent deployment but the molecular mechanisms by which these cells affect restenosis remain unclear. The p110δ isoform of phosphoinositide 3-kinase (PI3K) is mainly expressed in white blood cells. Here, we have investigated whether p110δ PI3K is involved in the pathogenesis of restenosis in a mouse model of carotid injury, which mimics the damage following arterial grafts. We used mice in which p110δ kinase activity has been disabled by a knockin (KI) point mutation in its ATP-binding site (p110δD910A/D910A PI3K mice). Wild-type (WT) and p110δD910A/D910A mice were subjected to longitudinal carotid injury. At 14 and 30 days after carotid injury, mice with inactive p110δ showed strongly decreased infiltration of inflammatory cells (including T lymphocytes and macrophages) and vascular smooth muscle cells (VSMCs), compared with WT mice. Likewise, PI-3065, a p110δ-selective PI3K inhibitor, almost completely prevented restenosis after artery injury. Our data showed that p110δ PI3K plays a main role in promoting neointimal thickening and inflammatory processes during vascular stenosis, with its inhibition providing significant reduction in restenosis following carotid injury. p110δ-selective inhibitors, recently approved for the treatment of human B-cell malignancies, therefore, present a new therapeutic opportunity to prevent the restenosis upon artery injury.

Potential Role of Axonal Chemorepellent Slit2 in Modulating Adventitial Inflammation in a Rat Carotid Artery Balloon Injury Model

Leukocyte infiltration of adventitial and perivascular tissues is an early event in the development of vascular remodeling after injury. We investigated whether Slit/Robo-an axonal chemorepellent system in vertebrate and invertebrate development-is activated during the inflammatory phase that follows endothelial denudation. Using the rat carotid artery model of angioplasty, we conducted a time course analysis of mRNAs encoding Slit ligands (Slit2 and Slit3) and Robo receptors (Robo1, Robo2, and Robo4), as well as proinflammatory cell adhesion molecule (CAM) genes. Adventitial inflammatory cells were counted in immunostained arterial sections. E-selectin, vascular CAM-1, and intercellular CAM-1 were upregulated 2-3 hours after injury, followed by infiltration of neutrophils and monocytes as evidenced by real-time polymerase chain reaction, in situ hybridization, and immunohistochemistry. Slit2, Slit3, and Robo genes exhibited no expression changes at 3 hours; however, they were markedly upregulated 1 day after angioplasty. Intercellular CAM-1 expression was reduced by 50%, and the number of adventitial neutrophils decreased by >75% 1 day after angioplasty. Slit2 has been shown to be a potent chemorepelent of leukocytes, endothelial cells, and smooth muscle cells. Thus, we decided to further investigate the localization of Slit2 in injured vessels. Immunohistochemical stainings revealed the presence of Slit2 within the vessel wall and in the perivascular vasa vasorum of naive and injured arteries. Double immunohistochemical analyses showed that infiltrating monocytes expressed Slit2 in the perivascular and adventitial tissues of injured arteries 1 and 3 days postangioplasty. In addition, recombinant full-length Slit2 and Slit2-N/1118, an N-terminal fragment of Slit2, inhibited stromal cell-derived factor 1-mediated migration of circulating rat peripheral blood mononuclear cells. In summary, adventitial activation of CAM genes and neutrophil infiltration preceded upregulation of Slit/Robo genes. Sli2 expression colocalized with infiltrating inflammatory cells in the adventitial layer. This temporospatial association suggests that leukocyte chemorepellent Slit2 may be involved in halting the adventitial accumulation of inflammatory cells in injured vessels.

Adenosine Attenuates Human Coronary Artery Smooth Muscle Cell Proliferation by Inhibiting Multiple Signaling Pathways That Converge on Cyclin D

The goal of this study was to determine whether and how adenosine affects the proliferation of human coronary artery smooth muscle cells (HCASMCs). In HCASMCs, 2-chloroadenosine (stable adenosine analogue), but not N(6)-cyclopentyladenosine, CGS21680, or N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide, inhibited HCASMC proliferation (A2B receptor profile). 2-Chloroadenosine increased cAMP, reduced phosphorylation (activation) of ERK and Akt (protein kinases known to increase cyclin D expression and activity, respectively), and reduced levels of cyclin D1 (cyclin that promotes cell-cycle progression in G1). Moreover, 2-chloroadenosine inhibited expression of S-phase kinase-associated protein-2 (Skp2; promotes proteolysis of p27(Kip1)) and upregulated levels of p27(Kip1) (cell-cycle regulator that impairs cyclin D function). 2-Chloroadenosine also inhibited signaling downstream of cyclin D, including hyperphosphorylation of retinoblastoma protein and expression of cyclin A (S phase cyclin). Knockdown of A2B receptors prevented the effects of 2-chloroadenosine on ERK1/2, Akt, Skp2, p27(Kip1), cyclin D1, cyclin A, and proliferation. Likewise, inhibition of adenylyl cyclase and protein kinase A abrogated 2-chloroadenosine's inhibitory effects on Skp2 and stimulatory effects on p27(Kip1) and rescued HCASMCs from 2-chloroadenosine-mediated inhibition. Knockdown of p27(Kip1) also reversed the inhibitory effects of 2-chloroadenosine on HCASMC proliferation. In vivo, peri-arterial (rat carotid artery) 2-chloroadenosine (20 μmol/L for 7 days) downregulated vascular expression of Skp2, upregulated vascular expression of p27(Kip1), and reduced neointima hyperplasia by 71% (P<0.05; neointimal thickness: control, 37 424±18 371 pixels; treated, 10 352±2824 pixels). In conclusion, the adenosine/A2B receptor/cAMP/protein kinase A axis inhibits HCASMC proliferation by blocking multiple signaling pathways (ERK1/2, Akt, and Skp2) that converge at cyclin D, a key G1 cyclin that controls cell-cycle progression.

Early changes of gene expression profiles in the rat model of arterial injury

PURPOSE

Restenosis caused by intimal hyperplasia (IH) remains a significant drawback for vascular interventions. It is crucial to understand the molecular mechanisms that control activation of smooth muscle cells (SMCs) after the injury in order to develop strategies to prevent IH. The purpose of the present study was to investigate the early alterations in arterial-wall gene expression after balloon injury in the rat carotid artery with focus on the induction of an inflammatory response.

MATERIALS AND METHODS

Twenty-four male Sprague-Dawley rats were subjected to injury of the left common carotid artery by using a 2-F Fogarty catheter. The arteries were harvested 5, 10, and 20 hours after injury. Uninjured arteries from an additional eight rats were used as controls. RNA was isolated and used for genome-wide microarray expression analysis, followed by validation of selected genes with quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemistry was performed on the cross-sectioned vessels.

RESULTS

Analysis of gene expression by microarrays showed that the most differentially expressed genes were primarily associated with inflammation, cell proliferation, migration, and adhesion. As confirmed by qRT-PCR, microarray data showed a significant (P < .005) upregulation of cytokines and chemokines (IL-6, CCL2, CXCL1, AIMP1, and CD44) just 5 hours after injury. Immunohistochemistry demonstrated that CCL2 and the adhesion receptor CD44 were expressed by SMCs in the early response to injury and in the absence of leukocyte infiltration.

CONCLUSIONS

Arterial injury is followed by an early induction of inflammatory genes in the vessel wall that appears to be confined to SMCs.

Endothelial cells overexpressing interleukin-8 receptors reduce inflammatory and neointimal responses to arterial injury

BACKGROUND

Interleukin-8 (IL8) receptors IL8RA and IL8RB on neutrophil membranes bind to IL8 and direct neutrophil recruitment to sites of inflammation, including acutely injured arteries. This study tested whether administration of IL8RA- and/or IL8RB-transduced rat aortic endothelial cells (ECs) accelerates adhesion of ECs to the injured surface, thus suppressing inflammation and neointima formation in balloon-injured rat carotid arteries. We tested the hypothesis that targeted delivery of ECs by overexpressing IL8RA and IL8RB receptors prevents inflammatory responses and promotes structural recovery of arteries after endoluminal injury.

METHODS AND RESULTS

Young adult male rats received balloon injury of the right carotid artery and were transfused intravenously with ECs (total, 1.5×10(6) cells at 1, 3, and 5 hours after injury) transduced with adenoviral vectors carrying IL8RA, IL8RB, and IL8RA/RB (dual transduction) genes, AdNull (empty vector), or vehicle (no EC transfusion). ECs overexpressing IL8Rs inhibited proinflammatory mediators expression significantly (by 60% to 85%) and reduced infiltration of neutrophils and monocytes/macrophages into injured arteries at 1 day after injury, as well as stimulating a 2-fold increase in reendothelialization at 14 days after injury. IL8RA-EC, IL8RB-EC, and IL8RA/RB-EC treatment reduced neointima formation dramatically (by 80%, 74%, and 95%) at 28 days after injury.

CONCLUSIONS

ECs with overexpression of IL8RA and/or IL8RB mimic the behavior of neutrophils that target and adhere to injured tissues, preventing inflammation and neointima formation. Targeted delivery of ECs to arteries with endoluminal injury provides a novel strategy for the prevention and treatment of cardiovascular disease.

CD40 ligand promotes Mac-1 expression, leukocyte recruitment, and neointima formation after vascular injury

High levels of circulating soluble CD40 ligand (sCD40L) are frequently found in patients with hypercholesterolemia, diabetes, ischemic stroke, or acute coronary syndromes, predicting an increased rate of atherosclerotic plaque rupture and restenosis after coronary/carotid interventions. Clinical restenosis is characterized in part by exaggerated neointima formation, but the underlying mechanism remains incompletely understood. This study investigated the role of elevated sCD40L in neointima formation in response to vascular injury in an atherogenic animal model and explored the molecular mechanisms involved. apoE(-/-) mice fed a Western diet developed severe hypercholesterolemia, significant hyperglycemia, and high levels of plasma sCD40L. Neointima formation after carotid denudation injury was exaggerated in the apoE(-/-) mice. In vivo, blocking CD40L with anti-CD40L monoclonal antibody attenuated the early accumulation of Ly-6G(+) neutrophils and Gr-1(+) monocytes (at 3 days) and the late accumulation of Mac-2(+) macrophages (at 28 days) in the denudated arteries; it also reduced the exaggerated neointima formation at 28 days. In vitro, recombinant CD40L stimulated platelet P-selectin and neutrophil Mac-1 expression and platelet-neutrophil co-aggregation and adhesive interaction. These effects were abrogated by anti-CD40L or anti-Mac-1 monoclonal antibody. Moreover, recombinant CD40L stimulated neutrophil oxidative burst and release of matrix metalloproteinase-9 in vitro. We conclude that elevated sCD40L promotes platelet-leukocyte activation and recruitment and neointima formation after arterial injury, potentially through enhancement of platelet P-selectin and leukocyte Mac-1 expression and oxidative activity.

Sex differences and estrogen modulation of the cellular immune response after injury

Cell-mediated immunity is extremely important for resolution of infection and for proper healing from injury. However, the cellular immune response is dysregulated following injuries such as burn and hemorrhage. Sex hormones are known to regulate immunity, and a well-documented dichotomy exists in the immune response to injury between the sexes. This disparity is caused by differences in immune cell activation, infiltration, and cytokine production during and after injury. Estrogen and testosterone can positively or negatively regulate the cellular immune response either by aiding in resolution or by compounding the morbidity and mortality. It is apparent that the hormonal dysregulation is dependent not only on the type of injury sustained but also the amount of circulating hormones. Therefore, it may be possible to design sex-specific therapies to improve immunological function and patient outcome.

Essential role of PKC-zeta in normal and angiotensin II-accelerated neointimal growth after vascular injury

The contribution of atypical protein kinase C (PKC)-zeta to ANG II-accelerated restenosis after endoluminal vascular injury was investigated by using the rat carotid balloon injury model. Exposure of injured arteries to ANG II resulted in an extensive neointimal thickening (1.9 times) compared with vehicle at day 14. Treatment with PKC-zeta antisense, but not scrambled, oligonucleotides reduced neointimal formation observed in the presence or absence of ANG II. Examination of early events (2 days) after injury showed an increase in cellularity in the perivascular area of the artery wall that was transferred to the adventitia and media after exposure to ANG II, events blocked by PKC-zeta antisense, but not scrambled, oligonucleotides. A positive correlation between medial cellularity at day 2 and extent of neointimal growth at day 14 was established. Immunohistochemical analysis showed that upregulation of inflammatory markers after injury, as well as infiltration of ED1(+) monocytes/macrophages from the perivascular area to the adventitia, was accelerated by ANG II. However, ANG II-stimulated medial increase in cellularity was proliferation independent, and these cells were monocyte chemoattractant protein-1(+)/vimentin(+) but ED1(-)/VCAM(-). PKC-zeta is degraded after injury, and inhibition of its neosynthesis in medial vascular smooth muscle cells or in infiltrating cells with PKC-zeta antisense attenuated medial cellularity and expression of inflammation mediators without reversing smooth muscle cell dedifferentiation. Together, these data indicate that PKC-zeta plays a critical role in normal and ANG II-accelerated neointimal growth through a mechanism involving upregulation of inflammatory mediators, leading to cell infiltration in the media of the vascular wall.

Characterization of a New Double-Injury Restenosis Model in the Rat Aorta

PURPOSE

To characterize a new rat model of restenosis for evaluation of local or systemic drug strategies.

METHODS

Arterial lesions were induced by placement of silicone cuffs around the aorta of Lewis rats. After 21 days, the cuffs were removed, and a subgroup of rat aortas was subjected to secondary balloon injury. Remodeling of wall compartments and cell kinetics were assessed morphometrically at 3, 7, 14, 21, and 28 days after the single and double-injury approaches. Immunohistochemistry was used to assess the distribution of macrophages, smooth muscle cells, and proliferating cells within the layers of the arterial wall in the experimental groups versus sham-operated and untreated controls.

RESULTS

After cuff placement, the adventitia initially undergoes significant enlargement, while the media shows a reduction in relative thickness. Accumulation of cells within the adventitia at 3 and 7 days is followed by a marked decline in cell density at 14 days, with simultaneously increasing cell numbers in the intima. At this time, activated macrophages are detected in the adventitia, indicating chronic inflammation. Following cuff placement, mild intimal hyperplasia develops. In the double-injury model, extensive neointimal hyperplasia forms rapidly, with a peak at 14 days.

CONCLUSIONS

This new double-injury model is technically easy, and multiple experiments can be accrued in short periods of time. It provides an additional platform to identify new targets and strategies for the prophylaxis of postangioplasty restenosis.

Survivin expression is up-regulated in vascular injury and identifies a distinct cellular phenotype

OBJECTIVES

The healing response to vascular injury is characterized by neointimal thickening. Proliferation and phenotypic transformation of vascular smooth muscle cells (SMCs) have been implicated in this process. We sought to investigate the role of survivin, a dual regulator of cell proliferation and apoptosis, in lesion formation after diverse forms of vascular injury.

METHODS

Rabbits underwent either carotid interposition vein grafting (n = 17) or bilateral femoral balloon injury (BI; n = 29); some in the BI group were placed on a high-cholesterol diet. A subset of BI arteries were treated with local adenoviral gene delivery of a survivin dominant negative-mutant (AdT34A) versus vector or saline controls. Survivin expression in vessels was analyzed by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and by immunohistochemistry (IHC), which also included markers of SMC differentiation. Specimens of human tissue including failed lower extremity bypass grafts and carotid plaque were also examined.

RESULTS

RT-PCR and IHC demonstrated increased survivin expression in all experimental models, colocalizing at early times with proliferating and alpha-actin-expressing cells but was largely absent in mature, contractile SMCs. Delivery of AdT34A after BI attenuated neointimal hyperplasia.

CONCLUSION

These studies provide strong evidence supporting a role for survivin in the cellular response to vascular injury.

CLINICAL RELEVANCE

The regulation of cell proliferation, death, and phenotype after vascular interventions remains incompletely understood. We investigated the role of the inhibitor of apoptosis protein survivin in diverse models of vascular injury. The results suggest that survivin is an important modulator of the generalized vascular injury response and may represent a relevant target for therapies targeting intimal hyperplasia.

Bone marrow-derived immune cells regulate vascular disease through a p27(Kip1)-dependent mechanism

The cyclin-dependent kinase inhibitors are key regulators of cell cycle progression. Although implicated in carcinogenesis, they inhibit the proliferation of a variety of normal cell types, and their role in diverse human diseases is not fully understood. Here, we report that p27(Kip1) plays a major role in cardiovascular disease through its effects on the proliferation of bone marrow-derived (BM-derived) immune cells that migrate into vascular lesions. Lesion formation after mechanical arterial injury was markedly increased in mice with homozygous deletion of p27(Kip1), characterized by prominent vascular infiltration by immune and inflammatory cells. Vascular occlusion was substantially increased when BM-derived cells from p27(-/-) mice repopulated vascular lesions induced by mechanical injury in p27(+/+) recipients, in contrast to p27(+/+) BM donors. To determine the contribution of immune cells to vascular injury, transplantation was performed with BM derived from RAG(-/-) and RAG(+/+) mice. RAG(+/+) BM markedly exacerbated vascular proliferative lesions compared with what was found in RAG(-/-) donors. Taken together, these findings suggest that vascular repair and regeneration is regulated by the proliferation of BM-derived hematopoietic and nonhematopoietic cells through a p27(Kip1)-dependent mechanism and that immune cells largely mediate these effects.

The role of inflammation in vascular injury and repair

Inflammation plays a critical role in the vascular response to injury. In particular, mechanical injury using techniques such as balloon angioplasty and stenting results in complex inflammatory reactions which influence proliferation of vessel wall constituents such as endothelial cells, smooth muscle cells, and extracellular matrix proteins. Inflammatory cells are recruited to the injured vessel wall initially as a reparative mechanism; however, these same inflammatory processes are also pivotal in the development of restenotic lesions. Leukocytes serve as the primary inflammatory cells but we now know that platelets produce a number of important inflammatory mediators. This review describes the mechanisms that regulate endothelial cell migration, smooth muscle cell activation, and extracellular matrix protein production, all of which are key components in the inflammatory response to vascular injury.