The integrin alpha2beta1 agonist, aggretin, promotes proliferation and migration of VSMC through NF-kB translocation and PDGF production

Sorting nexins: role in the regulation of blood pressure

Sorting nexins (SNXs) are a family of proteins that regulate cellular cargo sorting and trafficking, maintain intracellular protein homeostasis, and participate in intracellular signaling. SNXs are also important in the regulation of blood pressure via several mechanisms. Aberrant expression and dysfunction of SNXs participate in the dysregulation of blood pressure. Genetic studies show a correlation between SNX gene variants and the response to antihypertensive drugs. In this review, we summarize the progress in SNX-mediated regulation of blood pressure, discuss the potential role of SNXs in the pathophysiology and treatment of hypertension, and propose novel strategies for the medical therapy of hypertension.

TAS2R16 Activation Suppresses LPS-Induced Cytokine Expression in Human Gingival Fibroblasts

Sustained and non-resolved inflammation is a characteristic of periodontitis. Upon acute inflammation, gingival fibroblasts release cytokines to recruit immune cells to counter environmental stimuli. The intricate regulation of pro-inflammatory signaling pathways, such as NF-κB, is necessary to maintain periodontal homeostasis. Nonetheless, how inflammation is resolved has not yet been elucidated. In this study, 22 subtypes of taste receptor family 2 (TAS2Rs), as well as the downstream machineries of Gα-gustducin and phospholipase C-β2 (PLCβ2), were identified in human gingival fibroblasts (HGFs). Various bitter agonists could induce an intensive cytosolic Ca²⁺ response in HGFs. More importantly, TAS2R16 was expressed at a relatively high level, and its agonist, salicin, showed robust Ca²⁺ evocative effects in HGFs. Activation of TAS2R16 signaling by salicin inhibited the release of lipopolysaccharide (LPS)-induced pro-inflammatory cytokines, at least in part, by repressing LPS-induced intracellular cAMP elevation and NF-κB p65 nuclear translocation in HGFs. These findings indicate that TAS2Rs activation in HGFs may mediate endogenous pro-inflammation resolution by antagonizing NF-κB signaling, providing a novel paradigm and treatment target for the better management of periodontitis.

An antibody against Siglec-15 promotes bone formation and fracture healing by increasing TRAP+ mononuclear cells and PDGF-BB secretion

Osteoporosis (OP) is a common age-related disease characterized by a deterioration of bone mass and structure that predisposes patients to fragility fractures. Pharmaceutical therapies that promote anabolic bone formation in OP patients and OP-induced fracture are needed. We investigated whether a neutralizing antibody against Siglec-15 can simultaneously inhibit bone resorption and stimulate bone formation. We found that the multinucleation of osteoclasts was inhibited in SIGLEC-15 conditional knockout mice and mice undergoing Siglec-15 neutralizing antibody treatment. The secretion of platelet-derived growth factor-BB (PDGF-BB), the number of tartrate-resistant acid phosphatase-positive (TRAP⁺) mononuclear cells, and bone formation were significantly increased in the SIGLEC-15 conditional knockout mice and antibody-treated mice. The anabolic effect of the Siglec-15 neutralizing antibody on bone formation was blunted in mice with Pdgfb deleted in TRAP⁺ cells. These findings showed that the anabolic effect of the Siglec-15 neutralizing antibody was mediated by elevating PDGF-BB production of TRAP⁺ mononuclear cells. To test the therapeutic potential of the Siglec-15 neutralizing antibody, we injected the antibody in an ovariectomy-induced osteoporotic mouse model, which mimics postmenopausal osteoporosis in women, and in two fracture healing models because fracture is the most serious health consequence of osteoporosis. The Siglec-15 neutralizing antibody effectively reduced bone resorption and stimulated bone formation in estrogen deficiency-induced osteoporosis. Of note, the Siglec-15 neutralizing antibody promoted intramembranous and endochondral ossification at the damaged area of cortical bone in fracture healing mouse models. Thus, the Siglec-15 neutralizing antibody shows significant translational potential as a novel therapy for OP and bone fracture.

Cellular Crosstalk between Endothelial and Smooth Muscle Cells in Vascular Wall Remodeling

Pathological vascular wall remodeling refers to the structural and functional changes of the vessel wall that occur in response to injury that eventually leads to cardiovascular disease (CVD). Vessel wall are composed of two major primary cells types, endothelial cells (EC) and vascular smooth muscle cells (VSMCs). The physiological communications between these two cell types (EC–VSMCs) are crucial in the development of the vasculature and in the homeostasis of mature vessels. Moreover, aberrant EC–VSMCs communication has been associated to the promotor of various disease states including vascular wall remodeling. Paracrine regulations by bioactive molecules, communication via direct contact (junctions) or information transfer via extracellular vesicles or extracellular matrix are main crosstalk mechanisms. Identification of the nature of this EC–VSMCs crosstalk may offer strategies to develop new insights for prevention and treatment of disease that curse with vascular remodeling. Here, we will review the molecular mechanisms underlying the interplay between EC and VSMCs. Additionally, we highlight the potential applicable methodologies of the co-culture systems to identify cellular and molecular mechanisms involved in pathological vascular wall remodeling, opening questions about the future research directions.

Gene-metabolite networks associated with impediment of bone fracture repair in spaceflight

Adverse effects of spaceflight on musculoskeletal health increase the risk of bone injury and impairment of fracture healing. Its yet elusive molecular comprehension warrants immediate attention, since space travel is becoming more frequent. Here we examined the effects of spaceflight on bone fracture healing using a 2 mm femoral segmental bone defect (SBD) model. Forty, 9-week-old, male C57BL/6J mice were randomized into 4 groups: 1) Sham surgery on Ground (G-Sham); 2) Sham surgery housed in Spaceflight (FLT-Sham); 3) SBD surgery on Ground (G-Surgery); and 4) SBD surgery housed in Spaceflight (FLT-Surgery). Surgery procedures occurred 4 days prior to launch; post-launch, the spaceflight mice were house in the rodent habitats on the International Space Station (ISS) for approximately 4 weeks before euthanasia. Mice remaining on the Earth were subjected to identical housing and experimental conditions. The right femur from half of the spaceflight and ground groups was investigated by micro-computed tomography (µCT). In the remaining mice, the callus regions from surgery groups and corresponding femoral segments in sham mice were probed by global transcriptomic and metabolomic assays. µCT confirmed escalated bone loss in FLT-Sham compared to G-Sham mice. Comparing to their respective on-ground counterparts, the morbidity gene-network signal was inhibited in sham spaceflight mice but activated in the spaceflight callus. µCT analyses of spaceflight callus revealed increased trabecular spacing and decreased trabecular connectivity. Activated apoptotic signals in spaceflight callus were synchronized with inhibited cell migration signals that potentially hindered the wound site to recruit growth factors. A major pro-apoptotic and anti-migration gene network, namely the RANK-NFκB axis, emerged as the central node in spaceflight callus. Concluding, spaceflight suppressed a unique biomolecular mechanism in callus tissue to facilitate a failed regeneration, which merits a customized intervention strategy.

Smooth muscle cell-specific knockout of interferon gamma (IFN-γ) receptor attenuates intimal hyperplasia via STAT1-KLF4 activation

BACKGROUND

Intimal hyperplasia is a main contributor to in-stent restenosis. Previous researches have shown that interferon-gamma (IFN-γ), a pleiotropic pro-inflammatory factor, plays a pathological role in intimal hyperplasia. However, the specific role and molecular mechanism of vascular smooth muscle cells (VSMCs)-derived IFN-γ receptor in intimal hyperplasia remains unknown.

METHODS

We examined the distribution of IFN-γ receptor in human restenosis arteries. Then, the role of IFN-γ receptor in intimal hyperplasia was detected using VSMC-specific IFN-γ receptor-knock out carotid ligation injury models. We performed immunostaining, transwell assay and EdU staining to identify the role of IFN-γ in VSMCs proliferation and migration. The effect of IFN-γ on VSMCs phenotype switching was also investigated. Finally, we evaluated whether the mechanism of IFN-γ on intimal hyperplasia is STAT1-KLF4 dependent.

RESULTS

The distribution of IFN-γ receptor in human restenosis arteries with VSMC-rich neointima is eventually upregulated. Specific deletion of IFN-γ receptor exhibits thinner intima and lesser proliferating VSMCs. In vitro, treatment with IFN-γ promotes human aortic VSMC (HAVSMCs) proliferation and migration, whereas specifically knock out IFN-γ receptor results in the opposite effect. Deficiency of IFN-γ receptor regulates VSMCs phenotypic switching, such as upregulated contractile markers and downregulated proliferation markers. Mechanistic studies suggest that ablation of IFN-γ receptor prevents VSMCs proliferation, migration and dedifferentiation via STAT1-KLF4 activation.

CONCLUSION

These results reveal that knockout of VSMC-derived IFN-γ receptor potentiates neointimal hyperplasia by preventing VSMCs proliferation, migration and dedifferentiation. Our finding implies that targeting IFN-γ-STAT1-KLF4 signaling could provide a new therapeutic strategy to attenuate vessel restenosis.

TMEM98, a novel secretory protein, promotes endothelial cell adhesion as well as vascular smooth muscle cell proliferation and migration

Transmembrane protein 98 (TMEM98) is a novel gene, and its function has not been well investigated. In a prior study, we have shown that siRNA-mediated knockdown of TMEM98 inhibited interleukin-8 (IL-8) promoted endothelial cell (EC) adhesion, as well as vascular smooth muscle cell (VSMC) proliferation and migration in the vascular endothelial and smooth muscle cell dysfunction. Herein, we used gain- and loss-of-function approaches combined with biochemical techniques to further explore the role of TMEM98 in the vascular wall cell. The expression and secretion of TMEM98 was increased in cultured human umbilical vein endothelial cells (HUVECs) and VSMCs treated with IL-8 and platelet-derived growth factor-BB (PDGF-BB). Also, PDGF-BB secretion was increased in TMEM98-treated HUVECs and VSMCs. Thus, it appears that TMEM98 and PDGF-BB form a positive feedback loop in potentiation of EC adhesion, as well as VSMC proliferation and migration. Knockdown of TMEM98 mediated by siRNA inhibited PDGF-BB-promoted EC adhesion by downregulating the expression of ICAM-1 and VCAM-1, as well as impaired the proliferation and migration of VSMCs by suppressing the AKT/GSK3β/cyclin D1 signaling pathway and reducing the expression of β-catenin. Hence, TMEM98 promoted EC adhesion by inducing the expression of ICAM-1/VCAM-1 and triggered VSMC proliferation and migration by activating the ERK and AKT/GSK3β signaling pathways. Taken together, TMEM98 may serve as a potential therapeutic target for the clinical treatment of vascular endothelial and smooth muscle cell dysfunction.

Glucocorticoids Disrupt Skeletal Angiogenesis Through Transrepression of NF-κB-Mediated Preosteoclast Pdgfb Transcription in Young Mice

In the growing skeleton, angiogenesis is intimately coupled with osteogenesis. Chronic, high doses of glucocorticoids (GCs) are associated with decreased bone vasculature and induce osteoporosis and growth failure. The mechanism of GC-suppression of angiogenesis and relationship to osteoporosis and growth retardation remains largely unknown. Type H vessels, which are regulated by preosteoclast (POC) platelet-derived growth factor-BB (PDGF-BB), are specifically coupled with bone formation and development. We determined the effect of GCs on POC synthesis of PDGF-BB in relation to type H vessel formation, bone mass, and bone growth in the distal femur of 2-week-old young mice receiving prednisolone or vehicle for 2, 4, or 6 weeks. After 2 weeks of prednisolone, the number of POCs were unchanged while POC synthesis of PDGF-BB was reduced. Longer treatment with prednisolone reduced POCs numbers and PDGF-BB. These changes were associated with a reduction in type H vessels, bone formation rate, bone mass, and bone length at each time point. In vitro, excessive concentrations of prednisolone (10^-6 M) resulted in decreased PDGF-BB concentration and POC numbers. Conditioned medium from POC cultures treated with control concentration of prednisolone (10^-7 M) or recombinant PDGF-BB stimulated endothelial tube formation, whereas conditioned medium from control concentration of prednisolone-treated POC cultures neutralized by PDGF-BB antibody or excessive prednisolone inhibited endothelial tube formation. Administration of excessive prednisolone attenuated the P65 subunit of nuclear factor kappa B (NF-κB) binding to the Pdgfb promoter, resulting in lower Pdgfb transcription. Co-treatment with excessive prednisolone and the glucocorticoid receptor (GR) antagonist (RU486), GR siRNA, or TNFα rescued NF-κB binding to the Pdgfb promoter and endothelial tube formation. These results indicate that PDGF-BB synthesis in POCs is suppressed by GCs through transrepression of GR/NF-κB, thus inhibiting type H vessel formation and associated osteoporosis and growth failure. © 2020 American Society for Bone and Mineral Research.

The Role of Vascular Smooth Muscle Cells in Arterial Remodeling: Focus on Calcification-Related Processes

Arterial remodeling refers to the structural and functional changes of the vessel wall that occur in response to disease, injury, or aging. Vascular smooth muscle cells (VSMC) play a pivotal role in regulating the remodeling processes of the vessel wall. Phenotypic switching of VSMC involves oxidative stress-induced extracellular vesicle release, driving calcification processes. The VSMC phenotype is relevant to plaque initiation, development and stability, whereas, in the media, the VSMC phenotype is important in maintaining tissue elasticity, wall stress homeostasis and vessel stiffness. Clinically, assessment of arterial remodeling is a challenge; particularly distinguishing intimal and medial involvement, and their contributions to vessel wall remodeling. The limitations pertain to imaging resolution and sensitivity, so methodological development is focused on improving those. Moreover, the integration of data across the microscopic (i.e., cell-tissue) and macroscopic (i.e., vessel-system) scale for correct interpretation is innately challenging, because of the multiple biophysical and biochemical factors involved. In the present review, we describe the arterial remodeling processes that govern arterial stiffening, atherosclerosis and calcification, with a particular focus on VSMC phenotypic switching. Additionally, we review clinically applicable methodologies to assess arterial remodeling and the latest developments in these, seeking to unravel the ubiquitous corroborator of vascular pathology that calcification appears to be.

7-O-methylpunctatin, a Novel Homoisoflavonoid, Inhibits Phenotypic Switch of Human Arteriolar Smooth Muscle Cells

Remodeling of arterioles is a pivotal event in the manifestation of many inflammation-based cardio-vasculopathologies, such as hypertension. During these remodeling events, vascular smooth muscle cells (VSMCs) switch from a contractile to a synthetic phenotype. The latter is characterized by increased proliferation, migration, and invasion. Compounds with anti-inflammatory actions have been successful in attenuating this phenotypic switch. While the vast majority of studies investigating phenotypic modulation were undertaken in VSMCs isolated from large vessels, little is known about the effect of such compounds on phenotypic switch in VSMCs of microvessels (microVSMCs). We have recently characterized a novel homoisoflavonoid that we called 7-O-methylpunctatin (MP). In this study, we show that MP decreased FBS-induced cell proliferation, migration, invasion, and adhesion. MP also attenuated adhesion of THP-1 monocytes to microVSMCs, abolished FBS-induced expression of MMP-2, MMP-9, and NF-κB, as well as reduced activation of ERK1/2 and FAK. Furthermore, MP-treated VSMCs showed an increase in early (myocardin, SM-22α, SM-α) and mid-term (calponin and caldesmon) differentiation markers and a decrease in osteopontin, a protein highly expressed in synthetic VSMCs. MP also reduced transcription of cyclin D1, CDK4 but increased protein levels of p21 and p27. Taken together, these results corroborate an anti-inflammatory action of MP on human microVSMCs. Therefore, by inhibiting the synthetic phenotype of microVSMCs, MP may be a promising modulator for inflammation-induced arteriolar pathophysiology.

Cinnamaldehyde protects VSMCs against ox-LDL-induced proliferation and migration through S arrest and inhibition of p38, JNK/MAPKs and NF-κB

Cinnamaldehyde (Cin), as a traditional flavor constituent isolated from the bark of Cinnamonum cassia Presl, has been commonly used for - digestive, cardiovascular and immune system diseases. The pathology of vascular smooth muscle cells (VSMCs) accelerated the progression of atherosclerosis. In our study, we found that cinnamaldehyde significantly suppressed ox-LDL-induced VSMCs proliferation, migration and inflammatory cytokine overproduction, as well as foam cell formation in VSMCs and macrophages. Moreover, cinnamaldehyde inhibited the phosphorylation of p38, JNK and p65 NF-κB and increased heme oxygenase-1 (HO-1) activity. In addition, cinnamaldehyde reduced monocyte chemotactic protein-1 (MCP-1), matrix metalloproteinase-2 (MMP-2) and lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) expression. Furthermore, cinnamaldehyde arrested cell cycle in S phase. Thus, results indicated that cinnamaldehyde antagonized the ox-LDL-induced VSMCs proliferation, migration, inflammation and foam cell formation through regulation of HO-1, MMP-2, LOX-1 and blockage of cell cycle, and - suppression of p38, JNK/MAPK and NF-κB signaling pathways.

Vascular smooth muscle cell proliferation as a therapeutic target. Part 1: molecular targets and pathways

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules and signaling pathways. Herein, we recapitulated the importance of signaling cascades relevant for the regulation of vascular cell proliferation. Detailed understanding of the mechanism underlying this process is essential for the identification of new lead compounds (e.g., natural products) for vascular therapies.

Revisiting the Therapeutic Potential of Bothrops jararaca Venom: Screening for Novel Activities Using Connectivity Mapping

Snake venoms are sources of molecules with proven and potential therapeutic applications. However, most activities assayed in venoms (or their components) are of hemorrhagic, hypotensive, edematogenic, neurotoxic or myotoxic natures. Thus, other relevant activities might remain unknown. Using functional genomics coupled to the connectivity map (C-map) approach, we undertook a wide range indirect search for biological activities within the venom of the South American pit viper Bothrops jararaca. For that effect, venom was incubated with human breast adenocarcinoma cell line (MCF7) followed by RNA extraction and gene expression analysis. A list of 90 differentially expressed genes was submitted to biosimilar drug discovery based on pattern recognition. Among the 100 highest-ranked positively correlated drugs, only the antihypertensive, antimicrobial (both antibiotic and antiparasitic), and antitumor classes had been previously reported for B. jararaca venom. The majority of drug classes identified were related to (1) antimicrobial activity; (2) treatment of neuropsychiatric illnesses (Parkinson’s disease, schizophrenia, depression, and epilepsy); (3) treatment of cardiovascular diseases, and (4) anti-inflammatory action. The C-map results also indicated that B. jararaca venom may have components that target G-protein-coupled receptors (muscarinic, serotonergic, histaminergic, dopaminergic, GABA, and adrenergic) and ion channels. Although validation experiments are still necessary, the C-map correlation to drugs with activities previously linked to snake venoms supports the efficacy of this strategy as a broad-spectrum approach for biological activity screening, and rekindles the snake venom-based search for new therapeutic agents.

Can Integrin Agonists Have Cards to Play against Cancer? A Literature Survey of Small Molecules Integrin Activators

The ability of integrins to activate and integrate intracellular communication illustrates the potential of these receptors to serve as functional distribution hubs in a bi-directional signal transfer outside-in and inside-out of the cells. Tight regulation of the integrin signaling is paramount for normal physiological functions such as migration, proliferation, and differentiation, and misregulated integrin activity could be associated with several pathological conditions. Because of the important roles of integrins and their ligands in biological development, immune responses, leukocyte traffic, haemostasis, and cancer, their potential as therapeutic tools is now widely recognized. Nowadays extensive efforts have been made to discover and develop small molecule ligands as integrin antagonists, whereas less attention has been payed to agonists. In recent years, it has been recognized that integrin agonists could open up novel opportunities for therapeutics, which gain benefits to increase rather than decrease integrin-dependent adhesion and transductional events. For instance, a significant factor in chemo-resistance in melanoma is a loss of integrin-mediated adhesion; in this case, stimulation of integrin signaling by agonists significantly improved the response to chemotherapy. In this review, we overview results about small molecules which revealed an activating action on some integrins, especially those involved in cancer, and examine from a medicinal chemistry point of view, their structure and behavior.

A20 Haploinsufficiency Aggravates Transplant Arteriosclerosis in Mouse Vascular Allografts: Implications for Clinical Transplantation

BACKGROUND

Inflammation is central to the pathogenesis of transplant arteriosclerosis (TA). We questioned whether physiologic levels of anti-inflammatory A20 influence TA severity.

METHODS

We performed major histocompatibility complex mismatched aorta to carotid artery interposition grafts, using wild type (WT) or A20 heterozygote (HET) C57BL/6 (H-2) donors and BALB/c (H-2) recipients, and conversely BALB/c donors and WT/HET recipients. We analyzed aortic allografts by histology, immunohistochemistry, immunofluorescence, and gene profiling (quantitative real-time reverse-transcriptase polymerase chain reaction). We validated select in vivo A20 targets in human and mouse smooth muscle cell (SMC) cultures.

RESULTS

We noted significantly greater intimal hyperplasia in HET versus WT allografts, indicating aggravated TA. Inadequate upregulation of A20 in HET allografts after transplantation was associated with excessive NF-кB activation, gauged by higher levels of IkBα, p65, VCAM-1, ICAM-1, CXCL10, CCL2, TNF, and IL-6 (mostly localized to SMC). Correspondingly, cytokine-induced upregulation of TNF and IL-6 in human and mouse SMC cultures inversely correlated with A20 expression. Aggravated TA in HET versus WT allografts correlated with increased intimal SMC proliferation, and a higher number of infiltrating IFNγ and Granzyme B CD4 T cells and natural killer cells, and lower number of FoxP3 regulatory T cells. A20 haploinsufficiency in allograft recipients did not influence TA.

CONCLUSIONS

A20 haploinsufficiency in vascular allografts aggravates lesions of TA by exacerbating inflammation, SMC proliferation, and infiltration of pathogenic T cells. A20 single nucleotide polymorphisms associating with lower A20 expression or function in donors of vascularized allografts may inform risk and severity of TA, highlighting the clinical implications of our findings.

Convulxin, a C-type lectin-like protein, inhibits HCASMCs functions via WAD-motif/integrin-αv interaction and NF-κB-independent gene suppression of GRO and IL-8

Convulxin (CVX), a C-type lectin-like protein (CLPs), is a potent platelet aggregation inducer. To evaluate its potential applications in angiogenic diseases, the multimeric CVX were further explored on its mode of actions toward human coronary artery smooth muscle cells (HCASMCs). The N-terminus of β-chain of CVX (CVX-β) contains a putative disintegrin-like domain with a conserved motif upon the sequence comparison with other CLPs. Importantly, native CVX had no cytotoxic activity as examined by electrophoretic pattern. A Trp-Ala-Asp (WAD)-containing octapeptide, MTWADAEK, was thereafter synthesized and analyzed in functional assays. In the case of specific integrin antagonists as positive controls, the anti-angiogenic effects of CVX on HCASMCs were investigated by series of functional analyses. CVX showed to exhibit multiple inhibitory activities toward HCASMCs proliferation, adhesion and invasion with a dose- and integrin αvβ3-dependent fashion. However, the WAD-octapeptide exerting a minor potency could also work as an active peptidomimetic. In addition, flow cytometric analysis demonstrated both the intact CVX and synthetic peptide can specifically interact with integrin-αv on HCASMCs and CVX was shown to have a down-regulatory effect on the gene expression of CXC-chemokines, such as growth-related oncogene and interleukin-8. According to nuclear factor-κB (NF-κB) p65 translocation assay and Western blotting analysis, the NF-κB activation was not involved in the signaling events of CVX-induced gene expression. In conclusion, CVX may act as a disintegrin-like protein via the interactions of WAD-motif in CVX-β with integrin-αv on HCASMCs and it also is a gene suppressor with the ability to diminish the expression of two CXC-chemokines in a NF-κB-independent manner. Indeed, more extensive investigations are needed and might create a new avenue for the development of a novel angiostatic agent.

Atractylenolide I restores HO-1 expression and inhibits Ox-LDL-induced VSMCs proliferation, migration and inflammatory responses in vitro

Pathogenesis of atherosclerosis is characterized by the proliferation and migration of vascular smooth muscle cells (VSMCs) and inflammatory lesions. The aim of this study is to elucidate the effect of atractylenolide I (AO-I) on smooth muscle cell inflammation, proliferation and migration induced by oxidized modified low density lipoprotein (Ox-LDL). Here, We found that atractylenolide I inhibited Ox-LDL-induced VSMCs proliferation and migration in a dose-dependent manner, and decreased the production of inflammatory cytokines and the expression of monocyte chemoattractant protein-1 (MCP-1) in VSMCs. The study also identified that AO-I prominently inhibited p38-MAPK and NF-κB activation. More importantly, the specific heme oxygenase-1 (HO-1) inhibitor zinc protoporphyrin (ZnPP) IX partially abolished the beneficial effects of atractylenolide I on Ox-LDL-induced VSMCs. Furthermore, atractylenolide I blocked the foam cell formation in macrophages induced by Ox-LDL. In summary, inhibitory roles of AO-I in VSMCs proliferation and migration, lipid peroxidation and subsequent inflammatory responses might contribute to the anti-atherosclerotic property of AO-I.

Aggretin Venom Polypeptide as a Novel Anti-angiogenesis Agent by Targeting Integrin alpha2beta1

VEGF and VEGFR antibodies have been used as a therapeutic strategy to inhibit angiogenesis in many diseases; however, frequent and repeated administration of these antibodies to patients induces immunogenicity. In previous studies, we demonstrated that aggretin, a heterodimeric snake venom C-type lectin, exhibits pro-angiogenic activities via integrin α2β1 ligation. We hypothesised that small-mass aggretin fragments may bind integrin α2β1 and act as antagonists of angiogenesis. In this study, the anti-angiogenic efficacy of a synthesised aggretin α-chain C-terminus (AACT, residue 106–136) was evaluated in both in vitro and in vivo angiogenesis models. The AACT demonstrated inhibitory effects on collagen-induced platelet aggregation and HUVEC adhesion to immobilised collagen. These results indicated that AACT may block integrin α2β1−collagen interaction. AACT also inhibited HUVEC migration and tube formation. Aortic ring sprouting and Matrigel implant models demonstrated that AACT markedly inhibited VEGF-induced neovascularisation. In addition, induction of FAK/PI3K/ERK1/2 tyrosine phosphorylation and talin 1/2 associated with integrin β1 which are induced by VEGF were blocked by AACT. Similarly, tyrosine phosphorylation of VEFGR2 and ERK1/2 induced by VEGF was diminished in integrin α2-silenced endothelial cells. Our results demonstrate that AACT is a potential therapeutic candidate for angiogenesis related-diseases via integrin α2β1 blockade.

Integrin signaling in atherosclerosis

Atherosclerosis, a chronic lipid-driven inflammatory disease affecting large arteries, represents the primary cause of cardiovascular disease in the world. The local remodeling of the vessel intima during atherosclerosis involves the modulation of vascular cell phenotype, alteration of cell migration and proliferation, and propagation of local extracellular matrix remodeling. All of these responses represent targets of the integrin family of cell adhesion receptors. As such, alterations in integrin signaling affect multiple aspects of atherosclerosis, from the earliest induction of inflammation to the development of advanced fibrotic plaques. Integrin signaling has been shown to regulate endothelial phenotype, facilitate leukocyte homing, affect leukocyte function, and drive smooth muscle fibroproliferative remodeling. In addition, integrin signaling in platelets contributes to the thrombotic complications that typically drive the clinical manifestation of cardiovascular disease. In this review, we examine the current literature on integrin regulation of atherosclerotic plaque development and the suitability of integrins as potential therapeutic targets to limit cardiovascular disease and its complications.

Alkaloid rich fraction from Nelumbo nucifera targets VSMC proliferation and migration to suppress restenosis in balloon-injured rat carotid artery

AIMS

Restenosis- an adverse consequence following angioplasty, and atherosclerosis are characterized by abnormal vascular smooth muscle cell (VSMC) proliferation and migration leading to neo-intima formation. In the present study, we investigated the inhibitory effects of alkaloid rich fraction (ARF) from Nelumbo nucifera and isolated compound neferine on platelet-derived growth factor (PDGF-BB) induced VSMC proliferation and migration in vitro and neo-intima formation in a rat carotid artery injury model.

METHODS

PDGF-BB induced VSMC proliferation and migration was assessed using colorimetric assay and modified Boyden chamber method respectively. Gene expression of cell cycle associated molecules was determined by reverse transcription-polymerase chain reaction (RT-PCR). The signaling molecules such as PDGF-Rβ, extracellular regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK), P38, metalloproteinase (MMP)-9 and nuclear factor-kappa B (NF-κB) were determined by western blot analysis. Stress fiber formation was evaluated using immunofluorescence microscopy. The rat carotid artery balloon injury model was performed to assess the effect of ARF on neo-intima formation.

RESULTS

ARF possessed the strongest anti-oxidant activities. The anti-proliferative activity of both ARF and neferine was due to suppression of cyclin D1, cyclin E and cyclin-dependent kinase (Cdk) gene expression. Moreover, ARF and neferine inhibited PDGF-Rβ, ERK1/2, JNK and P38 activations and NF-κB translocation. Also, ARF and neferine inhibited VSMC migration by inhibiting MMP-9 activity without affecting cytoskeleton remodeling. In a rat carotid artery injury model, ARF inhibited neo-intima formation.

CONCLUSION

Our results indicate that ARF targets VSMC proliferation and migration to attenuate neo-intima formation by inhibition of PDGF-Rβ mediated signaling.

Dipeptidyl peptidase-4 inhibition by gemigliptin prevents abnormal vascular remodeling via NF-E2-related factor 2 activation

Dipeptidyl peptidase-4 (DPP-4) inhibitors exert a potent anti-hyperglycemic effect and reduce cardiovascular risk in type 2 diabetic patients. Several studies have shown that DPP-4 inhibitors including sitagliptin have beneficial effects in atherosclerosis and cardiac infarction involving reactive oxygen species. Here, we show that gemigliptin can directly attenuate the abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) via enhanced NF-E2-related factor 2 (Nrf2) activity. Gemigliptin dramatically prevented ligation injury-induced neointimal hyperplasia in mouse carotid arteries. Likewise, the proliferation of primary VSMCs was significantly attenuated by gemigliptin in a dose-dependent manner consistent with a decrease in phospho-Rb, resulting in G1 cell cycle arrest. We found that gemigliptin enhanced Nrf2 activity not only by mRNA expression, but also by increasing Keap1 proteosomal degradation by p62, leading to the induction of Nrf2 target genes such as HO-1 and NQO1. The anti-proliferative role of gemigliptin disappeared with DPP-4 siRNA knockdown, indicating that the endogenous DPP-4 in VSMCs contributed to the effect of gemigliptin. In addition, gemigliptin diminished TNF-α-mediated cell adhesion molecules such as MCP-1 and VCAM-1 and reduced MMP2 activity in VSMCs. Taken together, our data indicate that gemigliptin exerts a preventative effect on the proliferation and migration of VSMCs via Nrf2.

Dependence of fibroblast infiltration in tumor stroma on type IV collagen-initiated integrin signal through induction of platelet-derived growth factor

Cancer-associated fibroblasts play a crucial role in accelerating tumor progression, but there is a knowledge gap regarding the chemotactic signal activated in a tumor microenvironment. In this study, the expression of type IV collagen was knocked down using a lentiviral-mediated short hairpin RNA strategy. Although there was no obvious effect on cell growth in vitro, silencing the Col4-α1 gene decreased the tumorigenicity of B16F10 in C57BL/6 mice, which was accompanied by a reduction in the infiltration of alpha-smooth muscle actin-positive (α-SMA+) fibroblasts. Silencing the Col4-α1 gene or disrupting integrin engagement by blocking the antibody reduced the expression of platelet-derived growth factor A (PDGF-A), a potent chemotactic factor for fibroblasts. Furthermore, ectopic expression of the autoclustering integrin mutant significantly stimulated PDGF-A expression in murine B16F10 and human U118MG and Huh7 cells. PDGF-A-specific sh-RNA and neutralizing anti-PDGF-A antibody effectively inhibited the transwell migration of fibroblasts. Adding recombinant PDGF-A back to shCol cell-conditioned media restored the fibroblast-attraction ability indicating that PDGF-A is a major chemotactic factor for fibroblasts in the current study model. The integrin-associated PDGF-A production correlated with the activation of Src and ERK. High type IV collagen staining intensity colocalized with elevated PDGF-A expression was observed in tumor tissues obtained from hepatoma and glioma patients. The integrin signal pathway was activated by collagen engagement through Src and ERK, leading to enhanced PDGF-A production, which serves as a key regulator of fibroblast recruitment.

Uric acid promotes chemokine and adhesion molecule production in vascular endothelium via nuclear factor-kappa B signaling

BACKGROUND AND AIMS

Hyperuricemia is an important risk factor for atherosclerosis, yet the potential mechanisms are not well understood. Migration and adhesion of leukocytes to endothelial cells play key roles in initiation and development of atherosclerosis. We investigated monocyte-endothelial cell interactions and potential signaling pathways under uric acid (UA)-stimulated conditions.

METHODS AND RESULTS

Primary human umbilical vein endothelial cells (HUVECs) were cultured and exposed to different concentrations of UA for various periods. Experimental hyperuricemia rat models were established. Expression of chemoattractant protein-1 (MCP-1), interleukin 8 (IL-8), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were evaluated. Monocyte-endothelial cell interactions were elucidated by chemotaxis and adhesion assays, and nuclear factor-kappa B (NF-κB) pathway was studied using fluorescent microscopy and electrophoretic mobility shift assay. Results showed that high concentration of UA stimulated generation of chemokines and adhesion molecules in ex vivo and in vivo experiments. Migration and adhesion of human monocytic leukemia cell line THP-1 cells to HUVECs were promoted and activated NF-κB was significantly increased. UA-induced responses were ameliorated by organic anion transporter inhibitor probenecid and NF-κB inhibitor BAY11-7082. It was also observed that human endothelial cells expressed urate transporter-1, which was not regulated by UA.

CONCLUSION

High concentration of UA exerts unfavorable effects directly on vascular endothelium via the NF-κB signaling pathway, the process of which requires intracellular uptake of UA.

Tat 101-mediated enhancement of brain pericyte migration involves platelet-derived growth factor subunit B homodimer: implications for human immunodeficiency virus-associated neurocognitive disorders

In the era of antiretroviral therapy, although the human immunodeficiency virus (HIV) replication can be successfully controlled, complications of the CNS continue to affect infected individuals. Viral Tat protein is not only neurotoxic but has also been shown to disrupt the integrity of the blood-brain barrier (BBB). Although the role of brain microvascular endothelial cells and astrocytes in Tat-mediated impairment has been well documented, pericytes, which are important constituents of the BBB and play a key role in maintaining the integrity of the barrier, remain poorly studied in the context of HIV-associated neurocognitive disorders (HAND). In the present study, we demonstrated that exposure of human brain microvascular pericytes and C3H/10T1/2 cells to HIV-1 Tat101 resulted in increased expression of platelet-derived growth factor subunit B homodimer (PDGF-BB) and increased migration of the treated cells. Furthermore, we also demonstrated that this effect of Tat was mediated via activation of mitogen-activated protein kinases and nuclear factor-κB pathways. Secreted PDGF-BB resulted in autocrine activation of the PDGF-BB/PDGF β receptor signaling pathway, culminating ultimately into increased pericyte migration. Ex vivo relevance of these findings was further corroborated in isolated microvessels of HIV Tg26 mice that demonstrated significantly increased expression of PDGF-BB in isolated brain microvessels with a concomitant loss of pericytes. Intriguingly, loss of pericyte coverage was also detected in sections of frontal cortex from humans with HIV-encephalitis compared with the uninfected controls. These findings thus implicate a novel role of PDGF-BB in the migration of pericytes, resulting in loss of pericyte coverage from the endothelium with a subsequent breach of the BBB.

Andrographolide inhibits nuclear factor-κB activation through JNK-Akt-p65 signaling cascade in tumor necrosis factor-α-stimulated vascular smooth muscle cells

Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs) exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α). Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK), Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.

TL-118 and gemcitabine drug combination display therapeutic efficacy in a MYCN amplified orthotopic neuroblastoma murine model--evaluation by MRI

Neuroblastoma (NB) is the most common extra-cranial pediatric solid tumor with up to 50% of NB patients classified as having high-risk disease with poor long-term survival rates. The poor clinical outcome and aggressiveness of high-risk NB strongly correlates with enhanced angiogenesis, suggesting anti-angiogenic agents as attractive additions to the currently insufficient therapeutics. TL-118, a novel drug combination has been recently developed to inhibit tumor angiogenesis. In the current study, we used the SK-N-BE (2) cell line to generate orthotopic NB tumors in order to study the combinational therapeutic potential of TL-118 with either Gemcitabine (40 mg/kg; IP) or Retinoic acid (40 mg/kg; IP). We show that TL-118 treatment (n = 9) significantly inhibited tumor growth, increased cell apoptosis, reduced proliferation and extended mouse survival. Moreover, the reciprocal effect of TL-118 and Gemcitabine treatment (n = 10) demonstrated improved anti-tumor activity. The synergistic effect of these drugs in combination was more effective than either TL or Gemcitabine alone (n = 9), via significantly reduced cell proliferation (p<0.005), increased apoptosis (p<0.05) and significantly prolonged survival (2-fold; p<0.00001). To conclude, we demonstrate that the novel drug combination TL-118 has the ability to suppress the growth of an aggressive NB tumor. The promising results with TL-118 in this aggressive animal model may imply that this drug combination has therapeutic potential in the clinical setting.

Magnolol attenuates neointima formation by inducing cell cycle arrest via inhibition of ERK1/2 and NF-kappaB activation in vascular smooth muscle cells

BACKGROUND

Endovascular injury induces switching of contractile phenotype of vascular smooth muscle cells (VSMCs) to synthetic phenotype, thereby causing proliferation of VSMCs leading to intimal thickening. The purpose of this study was to assess the effect of magnolol on the proliferation of VSMCs in vitro and neointima formation in vivo, as well as the related cell signaling mechanisms.

METHODS

Tumor necrosis factor alpha (TNF-alpha) induced proliferation ofVSMCs was assessed using colorimetric assay. Cell cycle progression and mRNA expression of cell cycle associated molecules were determined by flow cytometry and reverse transcription polymerase chain reaction (RT-PCR) respectively. The signaling molecules such as ERK1/2,JNK, P38 and NF-kappaB were determined by Western blot analysis. In addition, rat carotid artery balloon injury model was performed to assess the effect of magnolol on neointima formation in vivo.

RESULTS

Oral administration of magnolol significantly inhibited intimal area and intimal/medial ratio (I/M). Our in vitro assays revealed magnolol dose dependently induced cell cycle arrest at G0/G1. Also, magnolol inhibited mRNA and protein expression of cyclin D1, cyclin E, CDK4 and CDK2 in vitro and in vivo. The cell cycle arrest was associated with inhibition of ERK1/2 phosphorylation and NF-kappaB translocation.

CONCLUSION

Magnolol suppressed proliferation of VSMCs in vitro and attenuated neointima formation in vivo by inducing cell cycle arrest at G0/G1 through modulation of cyclin D1, cyclin E, CDK4 and CDK2 expression.

GENERAL SIGNIFICANCE

Thus, the results suggest that magnolol could be a potential therapeutic candidate for the prevention of restenosis and atherosclerosis.

TNF-α promotes cerebral pericyte remodeling in vitro, via a switch from α1 to α2 integrins

Background

There is increasing evidence to suggest that pericytes play a crucial role in regulating the remodeling state of blood vessels. As cerebral pericytes are embedded within the extracellular matrix (ECM) of the vascular basal lamina, it is important to understand how individual ECM components influence pericyte remodeling behavior, and how cytokines regulate these events.

Methods

The influence of different vascular ECM substrates on cerebral pericyte behavior was examined in assays of cell adhesion, migration, and proliferation. Pericyte expression of integrin receptors was examined by flow cytometry. The influence of cytokines on pericyte functions and integrin expression was also examined, and the role of specific integrins in mediating these effects was defined by function-blocking antibodies. Expression of pericyte integrins within remodeling cerebral blood vessels was analyzed using dual immunofluorescence (IF) of brain sections derived from the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE).

Results

Fibronectin and collagen I promoted pericyte proliferation and migration, but heparan sulfate proteoglycan (HSPG) had an inhibitory influence on pericyte behavior. Flow cytometry showed that cerebral pericytes express high levels of α5 integrin, and lower levels of α1, α2, and α6 integrins. The pro-inflammatory cytokine tumor necrosis factor (TNF)-α strongly promoted pericyte proliferation and migration, and concomitantly induced a switch in pericyte integrins, from α1 to α2 integrin, the opposite to the switch seen when pericytes differentiated. Inhibition studies showed that α2 integrin mediates pericyte adhesion to collagens, and significantly, function blockade of α2 integrin abrogated the pro-modeling influence of TNF-α. Dual-IF on brain tissue with the pericyte marker NG2 showed that while α1 integrin was expressed by pericytes in both stable and remodeling vessels, pericyte expression of α2 integrin was strongly induced in remodeling vessels in EAE brain.

Conclusions

Our results suggest a model in which ECM constituents exert an important influence on pericyte remodeling status. In this model, HSPG restricts pericyte remodeling in stable vessels, but during inflammation, TNF-α triggers a switch in pericyte integrins from α1 to α2, thereby stimulating pericyte proliferation and migration on collagen. These results thus define a fundamental molecular mechanism in which TNF-α stimulates pericyte remodeling in an α2 integrin-dependent manner.

KCa3.1 channels mediate the increase of cell migration and proliferation by advanced glycation endproducts in cultured rat vascular smooth muscle cells

The mechanisms underlying the involvement of advanced glycation endproducts (AGEs) in diabetic atherosclerosis are not fully understood. The present study was designed to investigate whether intermediate-conductance Ca(2+)-activated K(+) channels (K(Ca)3.1 channels) are involved in migration and proliferation induced by AGEs in cultured rat vascular smooth muscle cells (VSMCs) using approaches of whole-cell patch voltage-clamp, cell proliferation and migration assay, and western blot analysis. It was found that the current density and protein level of K(Ca)3.1 channels were enhanced in cells incubated with AGE-BSA (bovine serum albumin), and the effects were reversed by co-incubation of AGE-BSA with anti-RAGE (anti-receptors of AGEs) antibody. The ERK1/2 inhibitors PD98059 and U0126, the P38-MAPK inhibitors SB203580 and SB202190, or the PI3K inhibitors LY294002 and wortmannin countered the K(Ca)3.1 channel expression by AGE-BSA. In addition, AGE-BAS increased cell migration and proliferation, and the effects were fully reversed with anti-RAGE antibody, the K(Ca)3.1 channel blocker TRAM-34, or K(Ca)3.1 small interfering RNA. These results demonstrate for the first time that AGEs-induced increase of migration and proliferation is related to the upregulation of K(Ca)3.1 channels in rat VMSCs, and the intracellular signals ERK1/2, P38-MAPK and PI3K are involved in the regulation of K(Ca)3.1 channel expression.

Subtilase cytotoxin enhances Escherichia coli survival in macrophages by suppression of nitric oxide production through the inhibition of NF-κB activation

Subtilase cytotoxin (SubAB), which is produced by certain strains of Shiga-toxigenic Escherichia coli (STEC), cleaves an endoplasmic reticulum (ER) chaperone, BiP/Grp78, leading to induction of ER stress and caspase-dependent apoptosis. SubAB alters the innate immune response. SubAB pretreatment of macrophages inhibited lipopolysaccharide (LPS)-induced production of both monocyte chemoattractant protein 1 (MCP-1) and tumor necrosis factor α (TNF-α). We investigated here the mechanism by which SubAB inhibits nitric oxide (NO) production by mouse macrophages. SubAB suppressed LPS-induced NO production through inhibition of inducible NO synthase (iNOS) mRNA and protein expression. Further, SubAB inhibited LPS-induced IκB-α phosphorylation and nuclear localization of the nuclear factor-κB (NF-κB) p65/p50 heterodimer. Reporter gene and chromatin immunoprecipitation (ChIP) assays revealed that SubAB reduced LPS-induced NF-κB p65/p50 heterodimer binding to an NF-κB binding site on the iNOS promoter. In contrast to the native toxin, a catalytically inactivated SubAB mutant slightly enhanced LPS-induced iNOS expression and binding of NF-κB subunits to the iNOS promoter. The SubAB effect on LPS-induced iNOS expression was significantly reduced in macrophages from NF-κB1 (p50)-deficient mice, which lacked a DNA-binding subunit of the p65/p50 heterodimer, suggesting that p50 was involved in SubAB-mediated inhibition of iNOS expression. Treatment of macrophages with an NOS inhibitor or expression of SubAB by E. coli increased E. coli survival in macrophages, suggesting that NO generated by macrophages resulted in efficient killing of the bacteria and SubAB contributed to E. coli survival in macrophages. Thus, we hypothesize that SubAB might represent a novel bacterial strategy to circumvent host defense during STEC infection.

Vinpocetine suppresses pathological vascular remodeling by inhibiting vascular smooth muscle cell proliferation and migration

Abnormal vascular smooth muscle cell (SMC) activation is associated with various vascular disorders such as atherosclerosis, in-stent restenosis, vein graft disease, and transplantation-associated vasculopathy. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. However, its role in pathological vascular remodeling remains unexplored. Herein, we show that systemic administration of vinpocetine significantly reduced neointimal formation in carotid arteries after ligation injury. Vinpocetine also markedly decreased spontaneous remodeling of human saphenous vein explants in ex vivo culture. In cultured SMCs, vinpocetine dose-dependently suppressed cell proliferation and caused G1-phase cell cycle arrest, which is associated with a decrease in cyclin D1 and an increase in p27Kip1 levels. In addition, vinpocetine dose-dependently inhibited platelet-derived growth factor (PDGF)-stimulated SMC migration as determined by the two-dimensional migration assays and three-dimensional aortic medial explant invasive assay. Moreover, vinpocetine significantly reduced PDGF-induced type I collagen and fibronectin expression. It is noteworthy that PDGF-stimulated phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2), but not protein kinase B, was specifically inhibited by vinpocetine. Vinpocetine powerfully attenuated intracellular reactive oxidative species (ROS) production, which largely mediates the inhibitory effects of vinpocetine on ERK1/2 activation and SMC growth. Taken together, our results reveal a novel function of vinpocetine in attenuating neointimal hyperplasia and pathological vascular remodeling, at least partially through suppressing ROS production and ERK1/2 activation in SMCs. Given the safety profile of vinpocetine, this study provides insight into the therapeutic potential of vinpocetine in proliferative vascular disorders.

Improved efficacy of a novel anti-angiogenic drug combination (TL-118) against colorectal-cancer liver metastases; MRI monitoring in mice

BACKGROUND

The poor prognosis of patients with colorectal-cancer liver metastases (CRLM) and the insufficiency of available treatments have raised the need for alternative curative strategies. We aimed to assess the therapeutic potential of TL-118, a new anti-angiogenic drug combination, for CRLM treatment, in a mouse model.

METHODS

The therapeutic potential of TL-118 was evaluated and compared with B20-4.1.1 (B20; anti-VEGF antibody) and rapamycin in CRLM-bearing mice. Tumour progression and the vascular changes were monitored by MRI. Additionally, mice survival, cell proliferation, apoptosis and vessel density were evaluated.

RESULTS

This study demonstrated an unequivocal advantage to TL-118 therapy by significantly prolonging survival (threefold) and reducing metastasis perfusion and vessel density (ninefold). The underlying mechanism for TL-118-treatment success was associated with hepatic perfusion attenuation resulting from reduced nitric-oxide (NO) serum levels as elucidated by using hemodynamic response imaging (HRI, a functional MRI combined with hypercapnia and hyperoxia). Further, systemic hepatic perfusion reduction during the initial treatment phase by adding NO inhibitor has proven to be essential for reaching maximal therapeutic effects for both TL-118 and B20.

CONCLUSION

TL-118 harbours a potential clinical benefit to CLRM patients. Moreover, the reduction of hepatic perfusion at early stages of anti-angiogenic therapies by adding NO inhibitor is crucial for achieving maximal anti-tumour effects.

Complex regulation and function of the inflammatory smooth muscle cell phenotype in atherosclerosis

Vascular smooth muscle cell (SMC) phenotypic modulation plays a key role in atherosclerosis and is classically defined as a switch from a 'contractile' phenotype to a 'synthetic' phenotype, whereby genes that define the contractile SMC phenotype are suppressed and proliferation and/or migratory mechanisms are induced. There is also evidence that SMCs may take on a 'proinflammatory' phenotype, whereby SMCs secrete cytokines and express cell adhesion molecules, e.g. IL-8, IL-6, and VCAM-1, respectively, which may functionally regulate monocyte and macrophage adhesion and other processes during atherosclerosis. Factors that drive the inflammatory phenotype are not limited to cytokines but also include hemodynamic forces imposed on the blood vessel wall and intimate interaction of endothelial cells with SMCs, as well as changes in matrix composition in the vessel wall. However, it is critical to recognize that our understanding of the complex interaction of these multiple signal inputs has only recently begun to shed light on mechanisms that regulate the inflammatory SMC phenotype, primarily through models that attempt to recreate this environment ex vivo. The goal of this review is to summarize our current knowledge in this area and identify some of the key unresolved challenges and questions requiring further study.