Murine sca1/flk1-positive cells are not endothelial progenitor cells, but B2 lymphocytes.

Circulating sca1+/flk1+ cells are hypothesized to be endothelial progenitor cells (EPCs) in mice that contribute to atheroprotection by replacing dysfunctional endothelial cells. Decreased numbers of circulating sca1+/flk1+ cells correlate with increased atherosclerotic lesions and impaired reendothelialization upon electric injury of the common carotid artery. However, legitimate doubts remain about the identity of the putative EPCs and their contribution to endothelial restoration. Hence, our study aimed to establish a phenotype for sca1+/flk1+ cells to gain a better understanding of their role in atherosclerotic disease. In wild-type mice, sca1+/flk1+ cells were mobilized into the peripheral circulation by granulocyte-colony stimulating factor (G-CSF) treatment and this movement correlated with improved endothelial regeneration upon carotid artery injury. Multicolor flow cytometry analysis revealed that sca1+/flk1+ cells predominantly co-expressed surface markers of conventional B cells (B2 cells). In RAG2-deficient mice and upon B2 cell depletion, sca1+/flk1+ cells were fully depleted. In the absence of monocytes, sca1+/flk1+ cell levels were unchanged. A PCR array focused on cell surface markers and next-generation sequencing (NGS) of purified sca1+/flk1+ cells confirmed their phenotype to be predominantly that of B cells. Finally, the depletion of B2 cells, including sca1+/flk1+ cells, in G-CSF-treated wild-type mice partly abolished the endothelial regenerating effect of G-CSF, indicating an atheroprotective role for sca1+/flk1+ B2 cells. In summary, we characterized sca1+/flk1+ cells as a subset of predominantly B2 cells, which are apparently involved in endothelial regeneration.

Regulatory T cells suppress the expression of COX-2 in vulnerable plaque.

COX-2 contributes to local inflammation in atherosclerotic lesions. Regulatory T cells (Tregs) enhance the stability of atherosclerotic plaques. The aim of this study was to detect the potential relationship between Tregs and COX-2 in vulnerable plaques. Thirty ApoE -/- mice were fed a high-fat diet, and a silastic perivascular collar was placed around the right common carotid artery to induce vulnerable plaques. Eight weeks after collar placement, the mice were divided randomly into three groups: control, PBS, and Treg groups. Four weeks later, the right common carotid arteries were collected to detect the expression of COX-2. The results showed that Tregs significantly suppressed the expression of COX-2 in vulnerable plaques. In an in vitro experiment, RAW264.7 cells were divided randomly into three groups, which were precultured without T cells or with CD4 + CD25- T cells or Tregs for 48 h with an anti-CD3 antibody; then the cells were stimulated with LPS for 24 h. The RAW264.7 cells were harvested for RT-PCR and western blot assays and the results showed that Tregs downregulated COX-2 expression in RAW264.7 cells. Therefore, Tregs inhibited the expression of COX-2 in vulnerable plaques and macrophages, and COX-2 inhibition may be an important effect of Tregs that results in atherosclerotic plaque stabilization.

Interleukin-9 mediates chronic kidney disease-dependent vein graft disease: a role for mast cells.

AIMS: Chronic kidney disease (CKD) is a powerful independent risk factor for cardiovascular events, including vein graft failure. Because CKD impairs the clearance of small proteins, we tested the hypothesis that CKD exacerbates vein graft disease by elevating serum levels of critical cytokines that promote vein graft neointimal hyperplasia. METHODS AND RESULTS: We modelled CKD in C57BL/6 mice with 5/6ths nephrectomy, which reduced glomerular filtration rate by 60%, and we modelled vein grafting with inferior-vena-cava-to-carotid interposition grafting. CKD increased vein graft neointimal hyperplasia four-fold, decreased vein graft re-endothelialization two-fold, and increased serum levels of interleukin-9 (IL-9) five-fold. By quantitative immunofluorescence and histochemical staining, vein grafts from CKD mice demonstrated a ∼two-fold higher prevalence of mast cells, and a six-fold higher prevalence of activated mast cells. Concordantly, vein grafts from CKD mice showed higher levels of TNF and NFκB activation, as judged by phosphorylation of NFκB p65 on Ser536 and by expression of VCAM-1. Arteriovenous fistula veins from humans with CKD also showed up-regulation of mast cells and IL-9. Treating CKD mice with IL-9-neutralizing IgG reduced vein graft neointimal area four-fold, increased vein graft re-endothelialization ∼two-fold, and reduced vein graft total and activated mast cell levels two- and four-fold, respectively. Treating CKD mice with the mast cell stabilizer cromolyn reduced neointimal hyperplasia and increased re-endothelialization in vein grafts. In vitro, IL-9 promoted endothelial cell apoptosis but had no effect on smooth muscle cell proliferation. CONCLUSION: CKD aggravates vein graft disease through mechanisms involving IL-9 and mast cell activation.

Resident Arterial Cells and Circulating Bone Marrow-Derived Cells both Contribute to Intimal Hyperplasia in a Rat Allograft Carotid Transplantation Model.

BACKGROUND/AIMS: Neointimal formation following vascular injury remains a major mechanism of restenosis, whereas the precise sources of neointimal cells are still uncertain. We tested the hypothesis that both injured arterial cells and non-arterial cells contribute to intimal hyperplasia. METHODS: Following allograft transplantation of the balloon-injured carotid common artery (n = 3-6), the cellular composition of the transplant grafts and the origins of neointimal cells were measured by immunohistochemistry and immunofluorescence staining. RESULTS: Smooth muscle actin (SMA)-positive and CD68-positive cells were clearly observed 14 days later in the neointima after allograft transplantation of the balloon-injured carotid common artery, where re-endothelialization was not yet complete. Green fluorescent protein (GFP) and wild-type (WT) allograft transplantation revealed that the majority of the neointima cells were apparently from the recipient (≈85%) versus the donor (≈15%). Both monocyte chemotactic protein-1 (MCP-1)/CCR2 and stromal cell-derived factor-1 (SDF-1)/CXCR4 signaling were involved in intimal hyperplasia, with bone marrow-derived cells also playing a role. CONCLUSION: These data support the hypothesis that intimal hyperplasia could develop in our novel rat allograft transplantation model of arterial injury, where neointima is attributable not only to local arterial cells but also non-arterial cells including the bone marrow.

G protein-coupled estrogen receptor inhibits vascular prostanoid production and activity.

Complications of atherosclerotic vascular disease, such as myocardial infarction and stroke, are the most common causes of death in postmenopausal women. Endogenous estrogens inhibit vascular inflammation-driven atherogenesis, a process that involves cyclooxygenase (COX)-derived vasoconstrictor prostanoids such as thromboxane A2. Here, we studied whether the G protein-coupled estrogen receptor (GPER) mediates estrogen-dependent inhibitory effects on prostanoid production and activity under pro-inflammatory conditions. Effects of estrogen on production of thromboxane A(2) were determined in human endothelial cells stimulated by the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-α). Moreover, Gper-deficient (Gper(-/-)) and WT mice were fed a pro-inflammatory diet and underwent ovariectomy or sham surgery to unmask the role of endogenous estrogens. Thereafter, contractions to acetylcholine-stimulated endothelial vasoconstrictor prostanoids and the thromboxane-prostanoid receptor agonist U46619 were recorded in isolated carotid arteries. In endothelial cells, TNF-α-stimulated thromboxane A2 production was inhibited by estrogen, an effect blocked by the GPER-selective antagonist G36. In ovary-intact mice, deletion of Gper increased prostanoid-dependent contractions by twofold. Ovariectomy also augmented prostanoid-dependent contractions by twofold in WT mice but had no additional effect in Gper(-/-) mice. These contractions were blocked by the COX inhibitor meclofenamate and unaffected by the nitric oxide synthase inhibitor l-N(G)-nitroarginine methyl ester. Vasoconstrictor responses to U46619 did not differ between groups, indicating intact signaling downstream of thromboxane-prostanoid receptor activation. In summary, under pro-inflammatory conditions, estrogen inhibits vasoconstrictor prostanoid production in endothelial cells and activity in intact arteries through GPER. Selective activation of GPER may therefore be considered as a novel strategy to treat increased prostanoid-dependent vasomotor tone or vascular disease in postmenopausal women.

Carbon Monoxide Releasing Molecule Accelerates Reendothelialization after Carotid Artery Balloon Injury in Rat.

OBJECTIVE: This study was aimed to investigate the effects of carbon monoxide releasing molecule (CORM-2), a novel carbon monoxide carrier, on the reendothelialization of carotid artery in rat endothelial denudation model. METHODS: Male rats subjected to carotid artery balloon injury were treated with CORM-2, inactive CORM-2 (iCORM-2) or dimethyl sulfoxide (DMSO). The reendothelialization capacity was evaluated by Evans Blue dye and the immunostaining with anti-CD31 antibody. The number of circulating endothelial progenitor cells (EPCs) was detected by flow cytometry. The proliferation, migration, and adhesion of human umbilical vein endothelial cells (HUVECs) were assessed by using [3H]thymidine, Boyden chamber and human fibronectin respectively. The expressions of protein were detected by using western blot analysis. RESULTS: CORM-2 remarkably accelerated the re-endothelialization 5 d later and inhibited neointima formation 28 d later. In addition, the number of peripheral EPCs significantly increased in CORM-2-treated rats than that in iCORM-2 or DMSO-treated rats after 5 d later. In vitro experiments, CORM-2 significantly enhanced the proliferation, migration and adhesion of HUVECs. The levels of Akt, eNOS phosphorylation, and NO generation in HUVECs were also much higher in CORM-2 treated group. Blocking of PI3K/Akt/eNOS signaling pathway markedly suppressed the enhanced migration and adhesion of HUVECs induced by CORM-2. CONCLUSION: CORM-2 could promote endothelial repair, and inhibit neointima formation after carotid artery balloon injury, which might be associated with the function changes of HUVECs regulated by PI3K/Akt/eNOS pathway.

Dihydroaustrasulfone alcohol inhibits PDGF-induced proliferation and migration of human aortic smooth muscle cells through inhibition of the cell cycle.

Dihydroaustrasulfone alcohol is the synthetic precursor of austrasulfone, which is a marine natural product, isolated from the Taiwanese soft coral Cladiella australis. Dihydroaustrasulfone alcohol has anti-inflammatory, neuroprotective, antitumor and anti-atherogenic properties. Although dihydroaustrasulfone alcohol has been shown to inhibit neointima formation, its effect on human vascular smooth muscle cells (VSMCs) has not been elucidated. We examined the effects and the mechanisms of action of dihydroaustrasulfone alcohol on proliferation, migration and phenotypic modulation of human aortic smooth muscle cells (HASMCs). Dihydroaustrasulfone alcohol significantly inhibited proliferation, DNA synthesis and migration of HASMCs, without inducing cell death. Dihydroaustrasulfone alcohol also inhibited platelet-derived growth factor (PDGF)-induced expression of cyclin-dependent kinases (CDK) 2, CDK4, cyclin D1 and cyclin E. In addition, dihydroaustrasulfone alcohol inhibited PDGF-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), whereas it had no effect on the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/(Akt). Moreover, treatment with PD98059, a highly selective ERK inhibitor, blocked PDGF-induced upregulation of cyclin D1 and cyclin E and downregulation of p27kip1. Furthermore, dihydroaustrasulfone alcohol also inhibits VSMC synthetic phenotype formation induced by PDGF. For in vivo studies, dihydroaustrasulfone alcohol decreased smooth muscle cell proliferation in a rat model of restenosis induced by balloon injury. Immunohistochemical staining showed that dihydroaustrasulfone alcohol noticeably decreased the expression of proliferating cell nuclear antigen (PCNA) and altered VSMC phenotype from a synthetic to contractile state. Our findings provide important insights into the mechanisms underlying the vasoprotective actions of dihydroaustrasulfone alcohol and suggest that it may be a useful therapeutic agent for the treatment of vascular occlusive disease.

[Cell surface adhesion molecules mediated stretch-induced HL-60 cell adhesion to mouse common carotid arteries].

OBJECTIVE: To compare the roles of vascular cell adhesion molecular-1 (VCAM-1) and P-selectin in stretch-induced HL-60 cell adhesion to mouse common carotid arteries. METHODS: After the isolated mouse common carotid arteries were perfused with HL-60 cells, the unbound leukocytes were washed away and the number of adherent cells in every single field was counted under a microscope. We first observed the effect of stretch on HL-60 cell adhesion to the endothelium of arteries under different magnitudes of luminal hydrostatic pressure. Then, the roles of VCAM-1 and P-selectin in stretch-induced HL-60 cell adhesion to mouse common carotid arteries were compared by the pretreatment of neutralizing antibodies against VCAM-1, P-selectin or isotype-matched control antibody, respectively. RESULTS: The increase in luminal hydrostatic pressure of carotid arteries led to the increase of the number of HL-60 adhesion cells, suggesting that stretch induced HL-60 cell adhesion in a magnitude-dependent manner. The pretreatment with the isotype-matched control antibody failed to induce a significant change of the number of HL-60 adhesion cells. In contrast, the pretreatment of both VCAM-1 and P-selectin neutralizing antibodies dramatically reduced the number of adherent leukocytes (P<0.05), although no statistical significance was observed between the two groups. CONCLUSION: Stretch can induce HL-60 cell adhesion to carotid arteries in a magnitude-dependent manner. VCAM-1 and P-selectin play some roles in mechanical stretch-induced HL-60 cell adhesion to mouse common carotid arteries.

High-resolution imaging of intravascular atherogenic inflammation in live mice.

RATIONALE: The inflammatory processes that initiate and propagate atherosclerosis remain poorly understood, largely because defining the intravascular behavior of immune cells has been technically challenging. Respiratory and pulsatile movements have hampered in vivo visualization of leukocyte accumulation in athero-prone arteries at resolutions achieved in other tissues. OBJECTIVE: To establish and to validate a method that allows high-resolution imaging of inflammatory leukocytes and platelets within the carotid artery of atherosusceptible mice in vivo. METHODS AND RESULTS: We have devised a procedure to stabilize the mouse carotid artery mechanically without altering blood dynamics, which dramatically enhances temporal and spatial resolutions using high-speed intravital microscopy in multiple channels of fluorescence. By applying this methodology at different stages of disease progression in atherosusceptible mice, we first validated our approach by assessing the recruitment kinetics of various leukocyte subsets and platelets in athero-prone segments of the carotid artery. The high temporal and spatial resolution allowed the dissection of both the dynamic polarization of and the formation of subcellular domains within adhered leukocytes. We further demonstrate that the secondary capture of activated platelets on the plaque is predominantly mediated by neutrophils. Finally, we couple this procedure with triggered 2-photon microscopy to visualize the 3-dimensional movement of leukocytes in intimate contact with the arterial lumen. CONCLUSIONS: The improved imaging of diseased arteries at subcellular resolution presented here should help resolve many outstanding questions in atherosclerosis and other arterial disorders.

Toll-like receptor 2/6 agonist macrophage-activating lipopeptide-2 promotes reendothelialization and inhibits neointima formation after vascular injury.

OBJECTIVE: Reendothelialization after vascular injury (ie, balloon angioplasty or stent implantation) is clinically extremely relevant to promote vascular healing. We here investigated the therapeutic potential of the toll-like receptor 2/6 agonist macrophage-activating lipopeptide (MALP)-2 on reendothelialization and neointima formation in a murine model of vascular injury. APPROACH AND RESULTS: The left common carotid artery was electrically injured, and reendothelialization was quantified by Evans blue staining after 3 days. A single injection of MALP-2 (1 or 10 µg, IV) after vascular injury accelerated reendothelialization (P<0.001). Proliferation of endothelial cells at the wound margins determined by 5-ethynyl-2'-deoxyuridine incorporation was significantly higher in MALP-2-treated animals (P<0.05). Furthermore, wire injury-induced neointima formation of the left common carotid artery was completely prevented by a single injection of MALP-2 (10 µg, IV). In vitro, MALP-2 induced proliferation (BrdU incorporation) and closure of an artificial wound of endothelial cells (P<0.05) but not of smooth muscle cells. Protein array and ELISA analysis of isolated primary endothelial cells and ex vivo stimulated carotid segments revealed that MALP-2 stimulated the release of multiple growth factors and cytokines predominantly from endothelial cells. MALP-2 induced a strong activation of the mitogen-activated protein kinase cascade in endothelial cells, which was attenuated in smooth muscle cells. Furthermore, MALP-2 significantly enhanced circulating monocytes and hematopoietic progenitor cells. CONCLUSIONS: The toll-like receptor 2/6 agonist MALP-2 promotes reendothelialization and inhibits neointima formation after experimental vascular injury via enhanced proliferation and migration of endothelial cells. Thus, MALP-2 represents a novel therapeutic option to accelerate reendothelialization after vascular injury.

Leukocyte-specific CCL3 deficiency inhibits atherosclerotic lesion development by affecting neutrophil accumulation.

OBJECTIVE: Despite common disbelief that neutrophils are involved in atherosclerosis, evidence is accumulating for a causal role of neutrophils in atherosclerosis. CC chemokine ligand (CCL)3 is an inflammatory chemokine and its expression is significantly increased during atherosclerotic lesion formation in mice. It has recently been shown that under conditions of inflammation neutrophils can migrate along a CCL3 gradient. In this study, we aimed to elucidate the role of leukocyte-derived CCL3 in atherogenesis. METHODS AND RESULTS: Irradiated low density lipoprotein receptor(-/-) mice, reconstituted with CCL3(-/-) or littermate bone marrow showed markedly reduced CCL3 response to lipopolysaccharide treatment, establishing the critical relevance of leukocytes as source of CCL3. Hematopoietic deficiency of CCL3 significantly reduced aortic sinus lesion formation by 31% after 12 weeks of western-type diet. Interestingly, whereas plaque macrophage, collagen, and vascular smooth muscle cell content were unchanged, neutrophil adhesion to and presence in plaques was significantly attenuated in CCL3(-/-) chimeras. These mice had reduced circulating neutrophil numbers, which could be ascribed to an increased neutrophil turnover and CCL3(-/-) neutrophils were shown to be less responsive toward the neutrophil chemoattractant CXC chemokine ligand 1. CONCLUSIONS: Our data indicate that under conditions of acute inflammation leukocyte-derived CCL3 can induce neutrophil chemotaxis toward the atherosclerotic plaque, thereby accelerating lesion formation.

Prevalence of circulating CD4+CD28null T cells is associated with early atherosclerotic damage in patients with end-stage renal disease undergoing hemodialysis.

CD4(+) T-cell subsets lacking surface CD28 in peripheral blood have been suggested to predispose people to atherosclerosis. To determine if CD4(+)CD28(null) T cells are involved in the immunopathological process of atherosclerotic damage in end-stage renal disease (ESRD) patients undergoing hemodialysis (HD), we characterized peripheral-blood CD4(+)CD28(null) T cells from HD patients and investigated the association between these cells and early atherosclerotic damage. Four color flow cytometric analyses showed that HD patients had significantly higher percentages of CD4(+)CD28(null) T cells in circulating blood than healthy subjects (HS). Most HD patient-derived CD4(+)CD28(null) T cells expressed higher levels of CX3CR1 and produced more intracellular IFN-γ, perforin and granzyme B than their counterparts. Regression analyses demonstrated that the increased levels of CD4(+)CD28(null) T cells were positively correlated to serum levels of C-reactive protein, suggesting systemic inflammation and atherosclerosis. Furthermore, phenotypic and functional studies of CD4(+)CD28(null) T cells showed that these cells were closely correlated with impaired flow-mediated vasodilation and increased intima-media thickness in the carotid artery, which are markers of early atherosclerosis. These data suggested that CD4(+)CD28(null) T cells are important effector cells in HD patients, and that these cells may have a critical role in mediating early atherosclerotic damage.

Partial ligation-induced carotid artery occlusion induces leukocyte recruitment and lipid accumulation--a shear stress model of atherosclerosis.

Recent studies suggest that disturbed blood flow-induced shear stress can induce atherosclerosis (ATH) in humans and animals without a high fat diet. Therefore, we hypothesize that partial ligation of the left carotid artery can generate disturbed blood flow and shear stress and would lead to ATH in a predisposed genetic model of Apo E(-/-) mice. The partial left carotid artery model was generated by ligating three out of four branches of the left carotid artery compared with controls which experienced similar surgery conditions but no ligation. Animals were sacrificed 2 weeks post-ligation and examined for plaque formation, infiltration of leukocytes, pro-inflammatory immune response, and blood flow velocity. Our findings suggest a significant (p < 0.05) increase in plaque formation and lipid deposition in the partial ligated animals compared with controls, confirmed with hematoxylin and eosin and oil red O staining. Furthermore, there was a significant (p < 0.05) increase in the number of M1 macrophages and release of pro-inflammatory cytokines, IL-6 and TNFα, as compared with the control. Moreover, partial ligated carotid arteries demonstrated disturbed blood flow as their systolic velocity was significantly reduced. In conclusion, our data suggest that partial ligation of the left carotid artery induces disturbed flow and shear stress in the predisposed genetic model of Apo E(-/-) mice and leads to significantly developed ATH. Similarities to clinical patients who develop ATH independent of a high fat diet show that this could be a potential animal model to examine various parameters in ATH.

Insulin resistance and cardiovascular risk factors in women with PCOS who have normal glucose tolerance test.

INTRODUCTION: We aimed to determine the insulin resistance in women with PCOS patients who have normal oral glucose tolerance test (OGTT) and to evaluate cardiovascular risk by measuring C-reactive protein (CRP) and carotid intimae-media thickness (CIMT). METHODS: A total of 34 patients and age and body mass matched 20 healthy control subjects were included to this prospective study. Both of patients and control groups were consisted of normal oral glucose tolerance test. Insulin resistance (IR) was estimated using HOMA-IR method. CRP, lipid and hormone levels were measured. CIMT was measured by Carotid Artery B-Mode ultrasonography. RESULTS: There was no significant difference between patients and controls in BMI, and waist circumference, lipid, TSH, LH, FSH, estradiol, and prolactin levels. Serum insulin, testosterone, DHEAS, ferritin levels and HOMA values were significantly higher in patient group. We found that 64.7% (n = 22/34) patients with PCOS had insulin resistance. Both of CIMT and CRP levels were significantly higher in the PCOS patients had BMI over 25 kg/m². CRP levels was significantly higher in the PCOS patients had waist circumference greater than 80 cm. CONCLUSION: We found insulin resistance in the women with PCOS even if OGTT was normal. Our data were similar to literature, the women with PCOS have increased risk of premature atherosclerosis and metabolic syndrome.

Perivascular innate immune events modulate early murine vein graft adaptations.

OBJECTIVE: Innate immunity drives numerous cardiovascular pathologies. Vein bypass grafting procedures are frequently accompanied by low-grade wound contamination. We hypothesized that a peri-graft innate immune challenge, via an outside-in route, augments inflammatory responses, which subsequently drive a component of negative vein graft wall adaptations; moreover, adipose tissue mediates this immune response. METHODS: The inferior vena cava from a donor mouse was implanted into the common carotid artery of a recipient mouse utilizing a validated cuff technique (9-week-old male C57BL/6J mice). Slow-release low-dose (5 µg) lipopolysaccharide (LPS) (n = 9) or vehicle (n = 9) was applied peri-graft; morphologic analysis was completed (day 28). In parallel, vein-grafted mice received peri-graft LPS (n = 12), distant subcutaneous LPS (n = 6), or vehicle (n = 12), then day-1 and -3 harvest of grafts and adipose tissue for cytokines and toll-like receptor (TLR) signaling mRNA expression (qRT-PCR). RESULTS: All recipient mice survived, and all vein grafts were patent. Acute low-dose local LPS challenge enhanced vein graft lumen loss (P = .04) and tended to augment intimal hyperplasia (P = .06). The surgical trauma of vein grafting universally upregulated key pro- and anti-inflammatory mediators within the day-1 graft wall, but varied on TLR signaling gene expression. Local and distant LPS accentuated these patterns until at least postoperative day 3. LPS challenge enhanced the inflammatory response in adipose tissue (locally > distantly); local LPS upregulated adipose TLR-4 dramatically. CONCLUSIONS: Perivascular and distant inflammatory challenges potentiate the magnitude and duration of inflammatory responses in the early vein graft wall, negatively modulating wall adaptations, and thus, potentially contribute to vein graft failure. Furthermore, surgery activates innate immunity in adipose tissue, which is augmented (regionally > systemically) by LPS. Modulation of these local and distant inflammatory signaling networks stands as a potential strategy to enhance the durability of vascular interventions such as vein grafts.

Vascular endothelial growth factor-induced osteopontin expression mediates vascular inflammation and neointima formation via Flt-1 in adventitial fibroblasts.

OBJECTIVE: Adventitia acts as an active participant in vascular inflammation but the precise mechanism underlying adventitia-mediated vascular inflammation is not fully understood. In this study, we sought to determine whether vascular endothelial growth factor (VEGF) regulates osteopontin (OPN) expression through Flt-1 in adventitial fibroblasts (AFs) to mediate vascular inflammation and neointima formation. METHODS AND RESULTS: In primary cultured AFs, VEGF increased intracellular and secreted OPN expression in a time- and dose-dependent manner, which was effectively suppressed by a specific anti-Flt-1 hexapeptide. Interestingly, VEGF treatment of AFs enhanced the capability of AF-conditioned medium to stimulate macrophages chemotaxis, and this effect was attenuated after blockade of OPN from AF-conditioned medium. Furthermore, perivascular delivery of anti-Flt-1 peptide preferentially concentrated in the adventitia resulted in a decrease of neointima formation after balloon injury in carotid arteries. The inhibition of neointima formation was preceded by significant reduction of VEGF and OPN expression with concurrent macrophage infiltration into adventitia after injury. Activation of extracellular signal-regulated kinase 1/2 pathway was involved in OPN upregulation and macrophage chemotaxis. CONCLUSIONS: These results demonstrate that VEGF/Flt-1 signaling plays a significant role in vascular inflammation and neointima formation by regulating OPN expression in AFs and provide insight into Flt-1 as a potential therapeutic target for vascular diseases.

Vitamin D deficiency, CD4+CD28null cells and accelerated atherosclerosis in chronic kidney disease.

AIM: Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease (CKD) patients. The role of vitamin D remains controversial in this process. We evaluated the relationship between 25-hydroxyvitamin D, abnormal T helper cells (CD4+CD28null cells), systemic inflammation and atherosclerosis in CKD patients. METHODS: A total of 101 stage 4-5 non-dialysis CKD patients and 40 healthy controls were studied. Common carotid artery intima media thickness (CCA-IMT) was measured with an ultrasound system. 25(OH) vitamin D and highly sensitive C-reactive protein (hsCRP) were measured in serum by enzyme linked immunosorbent assay. The frequency of circulating CD4+CD28null cells was evaluated by flowcytometry. RESULTS: CKD subjects exhibited higher CCA-IMT (0.71 ± 0.01 vs 0.56 ± 0.01 mm, P < 0.0001), hsCRP (90.7 ± 5.8 vs 50.1 ± 8.6 µg/mL, P < 0.0001), CD4+CD28null cell frequency (9.1 ± 0.9 vs 3.6 ± 0.5%, P < 0.0001) and lower 25(OH) vitamin D levels (17.9 ± 1.9 vs 26.9 ± 3.5 ng/mL, P < 0.0001). In CKD subjects, serum 25 (OH) vitamin D level showed a strong inverse correlation with CCA-IMT (r = -0.729, P < 0.0001) and correlated with CD4+CD28null cell frequency (r = -0.249, P = 0.01) and hsCRP (r = -0.2, P = 0.047). We also noted correlation of IMT with patient age (r = 0.291, P = 0.004) and CD4+CD28null cells (r = 0.34, P = 0.001). On multiple regression analysis, 25(OH) vitamin D level, diabetic status and CD4+CD28null cell frequency exhibited independent association with IMT in CKD subjects. CONCLUSIONS: Vitamin D deficiency, inflammatory activation and higher frequency of CD4+CD28null T lymphocyte population correlate with preclinical atherosclerotic changes in CKD population. These findings suggest possible linkage between vitamin D metabolism and T cell modulation - abnormalities that may contribute to development of atherosclerosis in CKD.

Selective modulation of nuclear factor of activated T-cell function in restenosis by a potent bipartite peptide inhibitor.

RATIONALE: Nuclear factor of activated T-cells (NFAT) is importantly implicated in pathological cardiac remodeling and vascular lesion formation. NFAT functionality is mainly regulated by calcineurin, a Ca(2+)-dependent multi-effector phosphatase. Calcineurin inhibitors such as cyclosporine A (CsA) were shown to be effective in the treatment of restenosis and vascular inflammation but with adverse side effects. OBJECTIVE: This prompted the design of more selective inhibitors such as VIVIT and inhibitors of NFAT-calcineurin association, which unfortunately have a poor potency precluding clinical use. METHODS AND RESULTS: Here, we describe the rational design of a potent bipartite inhibitor of NFAT-calcineurin interaction, MCV1, which targets two separate calcineurin docking motifs. Modeling, site-directed mutagenesis, and functional studies demonstrated that MCV1 acts by allosteric modulation of calcineurin. Comparable to CsA, MCV1 prevents NFAT activation at nanomolar potency without impairing calcineurin phosphatase activity, nuclear factor-κB nuclear import, and general cell signaling. In contrast, CsA but not MCV1-activated basal level extracellular signal-regulated kinases activity and prevented nuclear import of calcineurin, independent of NFAT activation. In vivo MCV1 abrogated NFAT-mediated T-cell activation in a model of PMA-elicited peritonitis, whereas topical application of MCV1 markedly reduced neointima formation in a mouse model of restenosis. CONCLUSIONS: We designed a bipartite NFAT inhibitor that is more potent than VIVIT and more selective than CsA. MCV1 constitutes not only a powerful tool to unravel NFAT function but also a potential drug candidate for the treatment of diseases implicating NFAT activation.

Changes in vascular function and structure in juvenile idiopathic arthritis.

OBJECTIVE: Chronic inflammatory diseases in adults have been associated with increased cardiovascular risk and impaired vascular function. We aimed to assess the presence of early vascular dysfunction in patients with juvenile idiopathic arthritis (JIA) and investigate the role of inherent inflammatory process of JIA in vascular health. METHODS: Thirty patients with JIA (age range 7-18 years) were compared to 33 age- and sex-matched controls. Endothelial function (brachial artery flow-mediated dilation [FMD]), carotid intima-media thickness (IMT), and arterial stiffness were examined. Endothelial inflammation was assessed by intercellular adhesion molecule 1 (ICAM-1) and P-selectin measurements. RESULTS: Patients with JIA showed decreased FMD compared to controls (P = 0.001), independent of age (P = 0.9 among age subgroups). Baseline differences in erythrocyte sedimentation rate, ICAM-1, and glucose between the 2 groups accounted for the difference in FMD. The presence of systemic JIA was associated with greater IMT compared to patients with oligoarticular disease, polyarticular disease, or controls (P = 0.014, P = 0.069, and P = 0.046, respectively). The difference in IMT between systemic versus oligoarticular/polyarticular JIA was attributed to the following risk factors: age, body mass index, blood pressure, disease activity, and corticosteroids use. There were no differences in arterial stiffness indices between JIA patients and controls or between patients with systemic versus nonsystemic disease. CONCLUSION: Endothelial function is impaired in patients with JIA at a very young age, while IMT is increased only in the presence of systemic JIA. Vascular dysfunction may be partly attributed to the effects of disease-related characteristics (inflammation, disease activity, and medications).

Post-menopausal hormone therapy reduces autoantibodies to oxidized apolipoprotein B100.

The aim of the study was to verify whether post-menopausal hormone replacement therapy (HRT) modifies autoantibody titers against oxidized low-density lipoprotein (LDL) (anti-LDLoxi), against epitopes of oxidized apolipoprotein B100 and common carotid intima-media thickness (IMT) in these women. Sixty-eight women in pre-menopause (PMW) and 216 in post-menopause (POMW) were recruited; eighty-three had undergone HRT for at least 12 months, where 48 received conjugated estrogens alone (EHRT) and 35 received conjugated estrogen and medroxyprogesterone acetate (CHRT). ELISA was used to determine autoantibodies. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities were assayed by radiometric methods. IMT was measured using Doppler ultrasound. Anti-oxidized LDL and anti-D antibodies increased by 40% (p ≤ 0.003) and 42% (p ≤ 0.006), respectively, with menopause. There was a surprising and significant 7% reduction in anti-D2 antibody titers with HRT (p ≤ 0.050), indicating a positive effect of treatment on the immune response to oxidized LDL. Combined HRT decreased activities of HL and LPL. HRT did not change common carotid IMT, which was increased by 32% as expected after menopause (p ≤ 0.030). This study describes, for the first time, the protective effect of HRT on decreasing autoantibody titers against oxidized apolipoprotein B in LDL.