Mechanisms in the inhibition of neointimal hyperplasia with triflavin in a rat model of balloon angioplasty

CD93 in macrophages: A novel target for atherosclerotic plaque imaging?

Noninvasive imaging atherosclerotic (AS) plaque is of great importance for early diagnosis. Recently, CD93 in MΦ was linked to atherosclerosis development. Herein, we have investigated whether CD93 in MΦ is a potential novel target for atherosclerotic plaque imaging. CD93^hi and CD93^lo MΦ were prepared with or without LPS stimulation, before biological activity was evaluated. A rat AS model was produced with left carotid artery clamped. Whole‐body/ex vivo phosphor autoradiography of the artery and biodistribution were investigated after incorporation of ³H‐2‐DG into CD93^hi and CD93^lo MΦ or after ¹²⁵I‐α‐CD93 (¹²⁵I‐anti‐CD93mAb) injection. The plaque tissue was subjected to CD93/CD68 immunofluorescence/immunohistochemistry staining. CD93^hi and CD93^lo MΦ cells were successfully prepared without significant effect on bioactivity after incorporative labelled with ³H‐2‐DG. The AS model was successfully established. Biodistribution studies showed that adoptive transfer of ³H‐2‐DG‐CD93^hi MΦ or ¹²⁵I‐ α‐CD93 injection resulted in accumulation of radioactivity within the atherosclerotic plaque in the clamped left carotid artery. T/NT (target/non‐target, left/right carotid artery) ratio was higher in the ³H‐2‐DG‐CD93^hi MΦ adoptive transfer group than in the ³H‐2‐DG‐CD93^lo MΦ group (p < .05). Plaque radioactivity in the ¹²⁵I‐α‐CD93 injection group was significantly higher than in the ¹²⁵I‐IgG control group (p < .01). The higher radioactivity accumulated in the clamped left carotid artery was confirmed by phosphor autoradiography. More importantly, CD93/CD68 double‐positive MΦ accumulated at the atherosclerotic plaque in ³H‐2‐DG‐CD93^hi MΦ adoptive transfer group, which correlated with plaque radioactivity (r = .99, p < .01). In summary, both adoptive‐transferred ³H‐2‐DG‐labelled CD93^hi MΦ and ¹²⁵I‐α‐CD93 injection specifically targeted CD93 in atherosclerotic plaque. CD93 is a potential target in atherosclerotic plaque imaging.

Role of Integrins in Modulating Smooth Muscle Cell Plasticity and Vascular Remodeling: From Expression to Therapeutic Implications

Smooth muscle cells (SMCs), present in the media layer of blood vessels, are crucial in maintaining vascular homeostasis. Upon vascular injury, SMCs show a high degree of plasticity, undergo a change from a “contractile” to a “synthetic” phenotype, and play an essential role in the pathophysiology of diseases including atherosclerosis and restenosis. Integrins are cell surface receptors, which are involved in cell-to-cell binding and cell-to-extracellular-matrix interactions. By binding to extracellular matrix components, integrins trigger intracellular signaling and regulate several of the SMC function, including proliferation, migration, and phenotypic switching. Although pharmacological approaches, including antibodies and synthetic peptides, have been effectively utilized to target integrins to limit atherosclerosis and restenosis, none has been commercialized yet. A clear understanding of how integrins modulate SMC biology is essential to facilitate the development of integrin-based interventions to combat atherosclerosis and restenosis. Herein, we highlight the importance of integrins in modulating functional properties of SMCs and their implications for vascular pathology.

Under-expression of α8 integrin aggravates experimental atherosclerosis

Integrins play an important role in vascular biology. The α8 integrin chain attenuates smooth muscle cell migration but its functional role in the development of atherosclerosis is unclear. Therefore, we studied the contribution of α8 integrin to atherosclerosis and vascular remodelling. We hypothesized that α8 integrin expression is reduced in atherosclerotic lesions, and that its under-expression leads to a more severe course of atherosclerosis. α8 Integrin was detected by immunohistochemistry and qPCR and α8 integrin-deficient mice were used to induce two models of atherosclerotic lesions. First, ligation of the carotid artery led to medial thickening and neointima formation, which was quantified in carotid cross-sections. Second, after crossing into ApoE-deficient mice, the formation of advanced vascular lesions with atherosclerotic plaques was quantified in aortic en face preparations stained with Sudan IV. Parameters of renal physiology and histopathology were assessed: α8 integrin was detected in the media of human and murine vascular tissue and was down-regulated in arteries with advanced atherosclerotic lesions. In α8 integrin-deficient mice (α8(-/-) ) as well as α8(+/-) and α8(+/+) littermates, carotid artery ligation increased media:lumen ratios in all genotypes, with higher values in ligated α8(-/-) and α8(+/-) compared to ligated α8(+/+) animals. Carotid artery ligation increased smooth muscle cell number in the media of α8(+/+) mice and, more prominently, of α8(-/-) or α8(+/-) mice. On an ApoE(-/-) background, α8(+/-) and α8(-/-) mice developed more atherosclerotic plaques than α8(+/+) mice. α8 Integrin expression was reduced in α8(+/-) animals. Renal damage with increased serum creatinine and glomerulosclerosis was detected in α8(-/-) mice only. Thus, under-expression of α8 integrin aggravates vascular lesions, while a complete loss of α8 integrin results in reduced renal mass and additional renal disease in the presence of generalized atherosclerosis. Our data support the hypothesis that integrin α8β1 has a protective role in arterial remodelling and atherosclerosis.

The potential for resident lung mesenchymal stem cells to promote functional tissue regeneration: understanding microenvironmental cues

Tissue resident mesenchymal stem cells (MSCs) are important regulators of tissue repair or regeneration, fibrosis, inflammation, angiogenesis and tumor formation. Bone marrow derived mesenchymal stem cells (BM-MSCs) and endothelial progenitor cells (EPC) are currently being considered and tested in clinical trials as a potential therapy in patients with such inflammatory lung diseases including, but not limited to, chronic lung disease, pulmonary arterial hypertension (PAH), pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD)/emphysema and asthma. However, our current understanding of tissue resident lung MSCs remains limited. This review addresses how environmental cues impact on the phenotype and function of this endogenous stem cell pool. In addition, it examines how these local factors influence the efficacy of cell-based treatments for lung diseases.

Artificial cold wave-induced cerebral infarction in rats with carotid atherosclerosis

To investigate the effects of cold on blood pressure, serum endothelin-1 content, serum nitric oxide content, and morbidity of cerebral infarction, as well as assess the therapeutic effect of nimodipine. A total of 200 rats were initially assigned to a normal group (n = 10), sham group (n = 10), and carotid atherosclerosis group (n = 180), and subsequently the animals in the carotid atherosclerosis group were randomly assigned to three groups: non-cold (n = 59), cold treatment (n = 58), and nimodipine (n = 58). Rats in the cold and nimodipine groups experienced an artificial cold wave. The temperature was set at 22°C for 12 h (7:00 am to 7:00 pm) and then at 4°C for another 12 h (7:00 pm to 7:00 am), representing a cycle. The animals underwent three cycles of cold. Rats in the nimodipine group were treated with nimodipine and those in the cold group with given an equal volume of intragastric normal saline for 3 days. Hematoxylin and eosin staining showed features of carotid atherosclerosis in all animals. Blood pressure fluctuated with alteration of temperature. A temperature decrease was accompanied by an increase of blood pressure and elevation of serum levels of endothelium-1 and nitric oxide. In addition, although nimodipine could prevent the cold-induced increase of blood pressure and elevation of serum endothelium-1 and nitric oxide levels, it had no effect on blood pressure fluctuation or morbidity of cerebral infarction. The results suggest that dramatic variation in temperature is one of the main causes of cold-induced fluctuation of blood pressure.

Intracellular targets of RGDS peptide in melanoma cells

Background

RGD-motif acts as a specific integrins-ligand and regulates a variety of cell-functions via extracellular action affecting cell-adhesion properties. However, increasing evidence identifies additional RGDS-functions at intracellular level. Previous reports show RGDS-internalization in endothelial cells, cardiomyocytes and lymphocytes, indicating intracellular targets such as caspase-8 and caspase-9, and suggest RGDS specific activity at cytoplasmic level. Given the role RGDS-peptides play in controlling proliferation and apoptosis in several cell types, investigating intracellular targets of RGDS in melanoma cells may un-reveal novel molecular targets and key pathways, potentially useful for a more effective approach to melanoma treatment.

Results

In the present study we show for the first time that RGDS-peptide is internalized in melanoma cells in a time-dependent way and exerts strong anti-proliferative and pro-apoptotic effects independently from its extracellular anti-adhesive action. RGES control-peptide did not show biological effects, as expected; nevertheless it is internalized, although with slower kinetics. Survivin, a known cell-cycle and survival-regulator is highly expressed in melanoma cells. Co-immunoprecipitation assays in cell lysates and overlay assays with the purified proteins showed that RGDS interacts with survivin, as well as with procaspase-3, -8 and -9. RGDS-peptide binding to survivin was found to be specific, at high affinity (Kd 27.5 μM) and located at the survivin C-terminus. RGDS-survivin interaction appeared to play a key role, since RGDS lost its anti-mitogenic effect in survivin-deprived cells with a specific siRNA.

Conclusions

RGDS inhibits melanoma growth with an adhesion-independent mechanism; it is internalized in melanoma cells and specifically interacts with survivin. The present data may indicate a novel role of RGDS-containing peptides physiologically released from the extracellular matrix and may suggest a possible novel anti-proliferation strategy in melanoma.

The Role of Integrins in Cancer and the Development of Anti-Integrin Therapeutic Agents for Cancer Therapy

Integrins have been reported to mediate cell survival, proliferation, differentiation, and migration programs. For this reason, the past few years have seen an increased interest in the implications of integrin receptors in cancer biology and tumor cell aggression. This review considers the potential role of integrins in cancer and also addresses why integrins are present attractive targets for drug design. It discusses of the several properties of the integrin-based chemotherapeutic agents currently under consideration clinically and provides an insight into cancer drug development using integrin as a target.

Integrin alpha(v)beta(3) as a target in the prevention of neointimal hyperplasia

Although major advances have been made in the prevention and treatment of restenosis following coronary and peripheral interventions, the persistent complications of thrombosis and reintervention remain a mainstay for repeat hospitalizations in this patient population. For many years, a ubiquitous cell surface receptor called alpha(v)beta(3) integrin was the target of investigators in the prevention of restenosis because its interaction with the extracellular matrix was believed to coordinate the migration of smooth muscle cells (SMCs) from the media to the intima, the seminal event in the formation of intimal occlusive lesion. After the publication of uniformly positive animal studies demonstrating that alpha(v)beta(3) integrin blockade led to a significant reduction in new intimal (neointimal) lesion formation, early clinical trials supported the association of avoidance of target lesion revascularization and the use of antagonists to the SMC integrin alpha(v)beta(3) and its related platelet integrin alpha(IIb)beta(3). However, a series of clinical trials subsequently demonstrated that these antagonists did not necessarily prevent revascularizations by inhibiting intimal hyperplasia per se. Additional animal studies subsequently showed that, indeed, in the setting of pre-existing SMCs in the intimal lesion (ie, atherosclerotic plaque, fatty streaks), inhibiting SMC migration by way of beta(3) integrin blockade was an ineffective approach in the prevention of intimal hyperplasia and restenosis. However, given the wealth of basic and clinical information on the alpha(v)beta(3) integrin and its antagonists, we discuss in this article our new approach to this old solution by targeting a new clinical problem of early failure arteriovenous access for hemodialysis. Given the uniqueness of arteriovenous access in that there are essentially no significant atherosclerotic lesions in the artery and vein prior to the anastomosis, the seminal event of the migration of SMCs from the media to the neointima could by targeted once again with beta(3) integrin antagonists.