New vessels, new approaches: angiogenesis as a therapeutic target in musculoskeletal disorders

A Molecular Troika of Angiogenesis, Coagulopathy and Endothelial Dysfunction in the Pathology of Avascular Necrosis of Femoral Head: A Comprehensive Review

Avascular necrosis of the femoral head (ANFH) is a painful disorder characterized by the cessation of blood supply to the femoral head, leading to its death and subsequent joint collapse. Influenced by several risk factors, including corticosteroid use, excessive alcohol intake, hypercholesterolemia, smoking and some inflammatory disorders, along with cancer, its clinical consequences are thrombus formation due to underlying inflammation and endothelial dysfunction, which collaborates with coagulopathy and impaired angiogenesis. Nonetheless, angiogenesis resolves the obstructed free flow of the blood by providing alternative routes. Clinical manifestations of early stage of ANFH mimic cysts or lesions in subchondral bone, vasculitis and transient osteoporosis of the hip, rendering it difficult to diagnose, complex to understand and complicated to cure. To date, the treatment methods for ANFH are controversial as no foolproof curative strategy is available, and these depend upon different severity levels of the ANFH. From an in-depth understanding of the pathological determinants of ANFH, it is clear that impaired angiogenesis, coagulopathy and endothelial dysfunction contribute significantly. The present review has set two aims, firstly to examine the role and relevance of this molecular triad (impaired angiogenesis, coagulopathy and endothelial dysfunction) in ANFH pathology and secondly to propose some putative therapeutic strategies, delineating the fact that, for the better management of ANFH, a combined strategy to curtail this molecular triangle must be composed rather than focusing on individual contributions.

Serum levels of angiogenesis-related factors in patients with psoriasis

Psoriasis is characterized by increased dermal vascularity, indicating that aberrant angiogenesis is associated with the pathogenesis of psoriasis. Data on angiogenesis-related factors in psoriasis patients are limited. We explored serum levels of angiogenesis-related factors in patients with psoriasis, and investigated their association with clinical severity and laboratory data. Psoriasis patients visiting our hospital from April 2013 to April 2018 and healthy controls were included in this study. Serum levels of angiopoietin-1, fibroblast growth factor (FGF)-basic, epidermal growth factor (EGF), platelet endothelial cell adhesion molecule (PECAM)-1, placental growth factor, and vascular endothelial growth factor (VEGF) were measured by LEGENDplex. Serum samples obtained from 10 healthy controls, 18 patients with psoriasis vulgaris (PsV), 24 patients with psoriatic arthritis (PsA), and 13 patients with generalized pustular psoriasis (GPP) were analyzed. The serum angiopoietin-1 level was elevated in the PsV, PsA, and GPP patients. GPP patients had a higher serum VEGF level than healthy controls. In contrast, serum levels of EGF and PECAM-1 were lower in the PsV, PsA, and GPP patients than in healthy controls. The serum FGF-basic level was lower in the PsA and GPP patients than in healthy controls. Serum levels of FGF-basic in PsA and GPP patients, PECAM-1 in PsA patients, and VEGF in GPP patients became closer to the respective levels in healthy controls after systemic therapy. The serum FGF-basic level was positively correlated with the psoriasis area and severity index and the number of circulating eosinophils in GPP patients. The serum VEGF level was correlated positively with the serum C-reactive protein (CRP) level and erythrocyte sedimentation rate, and negatively with the serum albumin level in GPP patients. In conclusion, our exploratory study revealed that psoriasis affects serum levels of certain angiogenesis-related factors. Some of these factors could be biomarkers of treatment outcomes, clinical severity, and systemic inflammation.

Emerging Targets for the Treatment of Osteoarthritis: New Investigational Methods to Identify Neo-Vessels as Possible Targets for Embolization

Osteoarthritis (OA) is the major cause of disability, affecting over 30 million US adults. Continued research into the role of neovascularization and inflammation related to osteoarthritis in large-animal models and human clinical trials is paramount. Recent literature on the pathogenetic model of OA has refocused on low-level inflammation, resulting in joint remodeling. As a result, this has redirected osteoarthritis research toward limiting or treating joint changes associated with persistent synovitis. The overall goal of this review is to better understand the cellular and tissue-specific mechanisms of inflammation in relation to a novel OA treatment modality, Genicular Artery Embolization (GAE). This article also assesses the utility and mechanism of periarticular neovascular embolization for the treatment of OA with a particular emphasis on the balance between pro-angiogenic and anti-angiogenic cytokines, inflammatory biomarkers, and imaging changes.

Hybridization-chain-reaction is a relevant method for in situ detection of M2d-like macrophages in a mini-pig model

Macrophages are a heterogeneous population of cells with an important role in innate immunity and tissue regeneration. Based on in vitro experiments, macrophages have been subdivided into five distinct subtypes named M1, M2a, M2b, M2c, and M2d, depending on the means of their activation and the cell surface markers they display. Whether all subtypes can be detected in vivo is still unclear. The identification of macrophages in vivo in the regenerating muscle could be used as a new diagnostic tool to monitor therapeutic strategies for tissue repair. The use of classical immunolabeling techniques is unable to discriminate between different M2 macrophages and a functional characterization of these macrophages is lacking. Using in situ hybridization coupled with hybridization-chain-reaction detection (HCR), we achieved the identification of M2d-like macrophages within regenerating muscle and applied this technique to understand the role of M2 macrophages in the regeneration of irradiated pig-muscle after adipose tissue stem cell treatment. Our work highlights the limits of immunolabeling and the usefulness of HCR analysis to provide valuable information for macrophage characterization.

Efficacy of wIRA in the treatment of sacroiliitis in male patients with ankylosing spondylitis and its effect on serum VEGF levels

Background

This study aimed to assess the efficacy of water-filtered infrared A (wIRA) in sacroiliitis in male patients with ankylosing spondylitis (AS) and the effect of wIRA therapy on serum vascular endothelial growth factor (VEGF).

Methods

One hundred twenty male AS patients with active sacroiliitis were randomly divided into wIRA group and control group. wIRA treatment was performed twice daily for 5 consecutive days with 24-h interval before switching the treatment (crossover design). Bath ankylosing spondylitis disease activity index (BASDAI) scores, pain visual analogue scale (VAS), and morning stiffness VAS were recorded prior to and after each treatment period. Additionally, C-reactive protein (CRP), serum VEGF, and resistance index (RI) of sacroiliac joints detected by ultrasonography were recorded at baseline and after the first and second treatment period, respectively. The efficacy was examined by using repeated measures analysis of variance (ANOVA).

Results

BASDAI, pain VAS, and morning stiffness VAS scores decreased significantly (P < 0.001) after wIRA treatment and no-wIRA treatment (control group), and the difference between the two groups was significant (P < 0.001). CRP declined and RI increased during the wIRA treatment as compared with the no-wIRA treatment (P < 0.001). The increase in RI was associated with improvement of pain VAS scores (P = 0.018), while serum VEGF was unaffected by the treatment.

Conclusions

wIRA treatment achieved symptom and pain relief for AS patients with active sacroiliitis. wIRA treatment also improved RI revealed by ultrasonography, and this effect was associated with improved pain VAS scores.

Angiogenesis Dysregulation in Psoriatic Arthritis: Molecular Mechanisms

There is evidence that psoriatic arthritis is closely linked to angiogenesis. Morphological changes described in blood vessels of psoriatic arthritis joints suggest the presence of a dysregulated angiogenesis resulting in the formation of immature vessels. Even if the reason of this inefficient angiogenesis is still unclear, an imbalance between angiogenic and antiangiogenic factors is probably responsible for inducing a dysregulated angiogenesis in psoriatic arthritis, which seems to be involved in its pathogenesis and clinical features. Nevertheless, among chronic arthritides, while angiogenesis in rheumatoid arthritis has been largely studied with a great amount of literature data, limited data on angiogenesis role in psoriatic arthritis are available. This review article is focused on current knowledge on the mechanisms responsible for dysregulated angiogenesis in psoriatic arthritis.

Bone Marrow Aspirate Concentrate-Enhanced Marrow Stimulation of Chondral Defects

Mesenchymal stem cells (MSCs) from bone marrow play a critical role in osteochondral repair. A bone marrow clot forms within the cartilage defect either as a result of marrow stimulation or during the course of the spontaneous repair of osteochondral defects. Mobilized pluripotent MSCs from the subchondral bone migrate into the defect filled with the clot, differentiate into chondrocytes and osteoblasts, and form a repair tissue over time. The additional application of a bone marrow aspirate (BMA) to the procedure of marrow stimulation is thought to enhance cartilage repair as it may provide both an additional cell population capable of chondrogenesis and a source of growth factors stimulating cartilage repair. Moreover, the BMA clot provides a three-dimensional environment, possibly further supporting chondrogenesis and protecting the subchondral bone from structural alterations. The purpose of this review is to bridge the gap in our understanding between the basic science knowledge on MSCs and BMA and the clinical and technical aspects of marrow stimulation-based cartilage repair by examining available data on the role and mechanisms of MSCs and BMA in osteochondral repair. Implications of findings from both translational and clinical studies using BMA concentrate-enhanced marrow stimulation are discussed.

Advancement of the Subchondral Bone Plate in Translational Models of Osteochondral Repair: Implications for Tissue Engineering Approaches

Subchondral bone plate advancement is of increasing relevance for translational models of osteochondral repair in tissue engineering (TE). Especially for therapeutic TE approaches, a basic scientific knowledge of its chronological sequence, possible etiopathogenesis, and clinical implications are indispensable. This review summarizes the knowledge on this topic gained from a total of 31 translational investigations, including 1009 small and large animals. Experimental data indicate that the advancement of the subchondral bone plate frequently occurs during the spontaneous repair of osteochondral defects and following established articular cartilage repair approaches for chondral lesions such as marrow stimulation and TE-based strategies such as autologous chondrocyte implantation. Importantly, this subchondral bone reaction proceeds in a defined chronological and spatial pattern, reflecting both endochondral ossification and intramembranous bone formation. Subchondral bone plate advancement arises earlier in small animals and defects, but is more pronounced at the long term in large animals. Possible etiopathologies comprise a disturbed subchondral bone/articular cartilage crosstalk and altered biomechanical conditions or neovascularization. Of note, no significant correlation was found so far between subchondral bone plate advancement and articular cartilage repair. This evidence from translational animal models adverts to an increasing awareness of this previously underestimated pathology. Future research will shed more light on the advancement of the subchondral bone plate in TE models of cartilage repair.

Macrophages and angiogenesis in rheumatic diseases

Angiogenesis plays a key role in several rheumatic diseases, including rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, systemic sclerosis, systemic lupus erythematosus, and vasculitides. An imbalance between angiogenic inducers and inhibitors seems to be a critical factor in pathogenesis of these diseases. Macrophages promote angiogenesis during rheumatoid arthritis. In addition, macrophages can produce a variety of pro-angiogenic factors that have been associated with the angiogenic response occurring during other rheumatic diseases. Lastly, macrophages could be a target in the treatment of rheumatoid arthritis and other rheumatic diseases. Nevertheless, further studies are needed to better elucidate the exact role of macrophage in angiogenesis in these diseases.

Emerging avenues linking inflammation, angiogenesis and Sjögren's syndrome

Sjögren's syndrome (SS) is an autoimmune disease characterized by an inflammatory mononuclear infiltration and the destruction of epithelial cells of the lachrymal and salivary glands. The aetiology is unknown. The expression "autoimmune epithelitis" has been proposed as an alternative to SS, in view of the emerging central role of the epithelial cells in the disease pathogenesis. At the biomolecular level, the epithelial cells play an important role in triggering the autoimmune condition via antigen presentation, apoptosis, and chemokine and cytokines release. Inflammation and angiogenesis are frequently coupled in the pathological conditions associated to autoimmune diseases, and an angiogenic imbalance contributes to the pathogenesis of a number of inflammatory disorders. This work reviews the current knowledge of the molecular and cellular mechanisms underlying the pathogenesis of the inflammatory reactions that characterize SS. The literature and our data on the role of angiogenesis in the pathophysiology of the disease are discussed.

Vascular endothelial growth factor in children with cyanotic and acyanotic and congenital heart disease

INTRODUCTION

Vascular endothelial growth factor is a potent stimulator of angiogenesis. Children with cyanotic congenital heart disease often experience the development of widespread formation of collateral blood vessels, which may represent a form of abnormal angiogenesis resulting in increased morbidity and mortality. We undertook the present study to determine whether children with cyanotic congenital heart disease have elevated serum levels of vascular endothelial growth factor compared to children with acyanotic heart disease.

MATERIAL AND METHODS

Serum was obtained from 35 children with cyanotic congenital heart disease and 30 children with acyanotic heart disease. Vascular endothelial growth factor levels were measured in the serum of these patients by sandwich enzyme immunoassay.

RESULTS

Vascular endothelial growth factor was significantly elevated in children with cyanotic congenital heart disease compared to children with acyanotic heart disease (150.3 ±48.1 vs. 85.4 ±18.7 pg/ml, respectively, p < 0.001). In the cyanotic group, oxygen saturation (SaO(2)) was negatively correlated with VEGF (r=-0.631, p < 0.001) while haemoglobin was positively correlated (r=0.781, p = 0.007). No significant correlations were found in the acyanotic group.

CONCLUSIONS

Children with cyanotic congenital heart disease have elevated systemic levels of vascular endothelial growth factor directly related to the degree of cyanosis (SaO(2) and haemoglobin levels). These findings suggest that the widespread formation of collateral vessels in these children may be mediated by vascular endothelial growth factor.

Neutrophils promote inflammatory angiogenesis via release of preformed VEGF in an in vivo corneal model

We investigated the role of neutrophilic cells (neutrophils) in inflammatory angiogenesis and explored the possible mechanisms involved. Corneal angiogenesis was induced in vivo with a 75% silver nitrate applicator. Depletion of neutrophils was accomplished by the intraperitoneal administration of RB6-8C5, a neutrophil-depleting antibody. Angiogenesis, neutrophil infiltration, and the localization of vascular endothelial growth factor (VEGF) were evaluated by biomicroscopic observations, histology, and immunohistochemistry in control and RB6-8C5 treatment groups. Protein levels of VEGF, macrophage inflammatory protein-1alpha (MIP-1alpha), macrophage inflammatory protein-2 (MIP-2), and tumor necrosis factor alpha in the cornea were determined by enzyme-linked immunosorbent assay. An in vitro model of neutrophil activation was also used to examine the ability of neutrophils to produce and release VEGF, MIP-1alpha, and MIP-2. At day 1 after injury, neutrophil infiltration in the cornea was highest, and VEGF was expressed in the infiltrating neutrophils. The enhanced protein levels of VEGF, MIP-1alpha, and MIP-2 correlated with the degree of neutrophil infiltration. Neutrophil depletion significantly inhibited corneal angiogenesis and reduced the protein levels of VEGF, MIP-1alpha, and MIP-2 in the cornea. Upon stimulation, isolated neutrophils released VEGF from preformed stores and MIP-1alpha and MIP-2 by de novo synthesis. Neutrophil depletion thus significantly impaired inflammatory angiogenesis, identifying neutrophils as an important player in inflammatory angiogenesis. Neutrophils may exercise their angiogenic function by releasing proangiogenic factors such as VEGF. Intervention measures targeting neutrophils may therefore help to deal with abnormal angiogenesis involved in chronic inflammatory diseases.

Angiogenesis as a novel component of inflammatory bowel disease pathogenesis

BACKGROUND & AIMS

Angiogenesis is a critical component of neoplastic and chronic inflammatory disorders, but whether angiogenesis also occurs in inflammatory bowel disease (IBD) has yet to be established. We assessed mucosal vascularization, expression of endothelial alphaVbeta3 integrin, angiogenic factors, and their bioactivity in Crohn's disease (CD) and ulcerative colitis (UC) mucosa.

METHODS

Mucosal endothelium was immunostained for CD31 and factor VIII and quantified by digital morphometry. alphaVbeta3 expression was studied in vivo by confocal microscopy and in vitro by flow cytometric analysis of human intestinal microvascular endothelial cells (HIMECs). Vascular endothelial growth factor (VEGF), interleukin (IL)-8, and bFGF levels were measured in mucosal extracts and cells and angiogenic bioactivity shown by induction of HIMEC migration and the corneal and chorioallantoic membrane angiogenesis assays.

RESULTS

Microvessel density was increased in IBD mucosa. Endothelial alphaVbeta3 was strongly expressed in IBD but only sporadically in normal mucosa and was up-regulated in HIMECs by VEGF, tumor necrosis factor alpha, and bFGF. IBD mucosal extracts induced a significantly higher degree of HIMEC migration than control mucosa, and this response was mostly dependent on IL-8 and less on basic fibroblast growth factor or vascular endothelial growth factor. Compared with normal mucosa, IBD mucosal extracts induced a potent angiogenic response in both the corneal and chorioallantoic membrane assays.

CONCLUSIONS

These results provide morphological, phenotypic and functional evidence of potent angiogenic activity in both CD and UC mucosa, indicating that the local microvasculature undergoes an intense process of inflammation-dependent angiogenesis. Thus, angiogenesis appears to be an integral component of IBD pathogenesis, providing the practical and conceptual framework for anti-angiogenic therapies in IBD.

Impact of sidestream whole smoke solutions on the outcome of wound repair and related angiogenesis

Wound angiogenesis is essential to support the regenerating tissue and any setback in angiogenesis may result in retarded wound repair. Cigarette smoking causes numerous adverse effects, some of which are associated with poor healing. The current experiment was carried out to elucidate the possible detrimental effects of sidestream whole smoke solutions (SSWSS) on wound healing and related angiogenesis, using a well-defined chicken dorsum excision wound assay. Gross, histopathologic, SEM and computer based 3D image-probing modalities were utilized to quantify different detrimental effects of SSWSS on the fundamental processes of wound healing. A total of 160 chicks, aged 1 week, divided in eight groups were topically exposed for 8 days to SSWSS with different nicotine concentrations. At day 6 and day 8 post-wounding, very highly significant reduction (P<0.001) in wound closure was observed among all SSWSS treated groups. Histological and SEM evaluation of SSWSS treated wounds unveiled deteriorated dermal matrix, delayed re-epithelialization and retarded neovascularization. Moreover, image-probing exploration of SSWSS treated wounds also divulge a very highly significant decrease (P<0.001) in angular spectrum, Sa, Sy and Sci, at day 6 post-wounding. Our study suggests that the cumulative effect of different components of SSWSS has a negative impact on wound healing and related angiogenesis. Furthermore, our study demonstrates the effects that can contribute to abnormal healing and may explain why people who are consistently exposed to sidestream smoke suffer from slow healing and excessive scarring of wounds, much like the smokers themselves.

Serum VEGF and b-FGF profiles after tension-free or conventional hernioplasty

BACKGROUND

Angiogenesis is strongly influenced by vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF), whose production is also regulated by interferon (IFN)-gamma and interleukin (IL)-10. The aim of this study was to evaluate the modifications of serum VEGF, b-FGF, IFN-gamma and IL-10 levels in patients with inguinal hernia undergoing hernioplasty with the Lichtenstein technique (LH) using polypropylene mesh or with Bassini open conventional inguinal hernia repair (BH).

MATERIALS AND METHODS

Randomly, 16 patients underwent BH, and 16 were treated with the LH technique using polypropylene mesh. Blood samples were collected 24 h prior to surgery and then 6, 24, 48 and 168 h postoperatively. The serum concentrations of VEGF, b-FGF, IFN-gamma and IL-10 were evaluated.

RESULTS

In BH patients, a peak of VEGF synthesis at 6 h with a normalization of this parameter 24 h after surgery has been observed. In the same subjects, b-FGF synthesis increased after surgery reaching significant levels 48 h later. On the contrary, in LH patients, a decrease in the serum VEGF and b-FGF concentrations was detected after surgery and their increase afterwards. IL-10 was increased in both groups 6 h after operation and declined to preoperative levels 24 h afterwards. IFN-gamma enhanced in LH patients 6 h after surgery, whereas no modifications were detected in BH subjects.

CONCLUSIONS

This preliminary study shows that VEGF and b-FGF modifications, associated with alterations of cytokine secretion, are detectable in human undergoing hernioplasty, and suggests that they could somehow influence in the wound-healing process.

Vascular endothelial growth factor and angiogenesis

Angiogenesis is a hallmark of wound healing, the menstrual cycle, cancer, and various ischemic and inflammatory diseases. A rich variety of pro- and antiangiogenic molecules have already been discovered. Vascular endothelial growth factor (VEGF) is an interesting inducer of angiogenesis and lymphangiogenesis, because it is a highly specific mitogen for endothelial cells. Signal transduction involves binding to tyrosine kinase receptors and results in endothelial cell proliferation, migration, and new vessel formation. In this article, the role of VEGF in physiological and pathological processes is reviewed. We also discuss how modulation of VEGF expression creates new therapeutic possibilities and describe recent developments in this field.

Vascular endothelial growth factor induction by prostaglandin E2 in human airway smooth muscle cells is mediated by E prostanoid EP2/EP4 receptors and SP-1 transcription factor binding sites

Prostaglandin E2 (PGE2) can increase endothelial vascular endogrowth factor A (VEGF-A) production but the mechanisms involved are unclear. Here we characterized the transcriptional mechanisms involved in human airway smooth muscle cells (HASMC). PGE2 increased VEGF-A mRNA and protein but not mRNA stability. PGE2 stimulated the activity of a transiently transfected 2068-bp (-2018 to +50) VEGF-A promoter-driven luciferase construct. Functional 5' deletional analysis mapped the PGE2 response element to the 135-bp sequence (-85/+50) of the human VEGF-A promoter. PGE2-induced luciferase activity was reduced in cells transfected with a 135-bp VEGF promoter fragment containing mutated Sp-1 binding sites but not in cells transfected with a construct containing mutated EGR-1 binding sites. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed binding of Sp-1 to the VEGF promoter. PGE2 increased phosphorylation of Sp-1 and luciferase activity of a transfected Sp-1 reporter construct. PGE receptor agonists EP2 (ONO-AE1 259) and EP4 (ONO-AE1 329) mimicked the effect of PGE2, and reverse transcription-PCR, Western blotting, and flow cytometry confirmed the presence of EP2 and EP4 receptors. VEGF protein release and Sp-1 reporter activity were increased by forskolin and isoproterenol, which increase cytosolic cAMP, and the cAMP analogue, 8-bromoadenosine-3',5'-cyclophosphoric acid. These studies suggest that PGE2 increases VEGF transcriptionally and involves the Sp-1 binding site via a cAMP-dependent mechanism involving EP2 and EP4 receptors.

Antibody phage display technologies with special reference to angiogenesis

The presence of blood vessels is a prerequisite for normal development, tissue growth, and tissue repair. However, its abnormal occurrence or absence can also potentiate disease processes. Angiogenic therapies have been used to stimulate blood vessel growth in ischemic conditions such as severe end-stage peripheral vascular disease, ischemic heart disease and stroke and for inhibition of angiogenesis in tumors. The targeting and identification of novel endothelial cell (EC) markers that can ultimately be used in angiogenic strategies is an expanding field but is limited by the availability of reagents. For instance repeated injection of mouse monoclonal antibodies (Mabs) against angiogenic EC, can result in the production of autoantibodies. Therefore, these mouse Mabs cannot be used for therapeutic purposes. Phage display technology was employed in this context to select antibodies, proteins, and peptides against known or novel EC antigens. Furthermore, technologies have been developed that enable the specific targeting of epitopes on cells including the endothelium with high-affinity/avidity antibodies. The focus for these antibody targeting strategies are markers that are unique or up-regulated on angiogenic EC including the vascular endothelial growth factor receptor (VEGFR) KDR, endoglin (CD105), and the extracellular domain B (ED-B) domain of fibronectin (FN). These markers are reviewed herein.

Human immunodeficiency virus vector-mediated intra-articular expression of angiostatin inhibits progression of collagen-induced arthritis in mice

We examined the feasibility of the human immunodeficiency virus (HIV) vector-mediated local expression of angiostatin in the treatment of murine collagen-induced arthritis in a mouse model generated by immunization with bovine type II collagen and Freund's complete adjuvant. The HIV vector containing the murine angiostatin expression unit (HIV-angiostatin) was injected into right knee joints after arthritis development; the HIV vector containing the enhanced green fluorescein protein (EGFP) marker gene (HIV-EGFP) was injected into the left joints. Quantitative histological evaluation demonstrated that synovial cell hyperplasia and pannus formation were significantly reduced in the right knee joints as determined by this protocol. Suppression of radiographical changes in the ipsilateral paws was also observed. These results indicate that the HIV vector-mediated expression of angiostatin efficiently inhibits the progression of collagen-induced arthritis. Angiostatic gene therapy may provide a new approach to the effective treatment of rheumatoid arthritis.

Power Doppler ultrasound of rheumatoid synovitis: quantification of therapeutic response

The aim of this study is to quantify power Doppler assessment of therapeutic response in rheumatoid synovitis. 13 patients (6 male, 7 female) with rheumatoid arthritis, who had an acute exacerbation of small joint synovitis in the hands, were examined with quantitative power Doppler, before and after intravenous corticosteroid treatment. All patients were examined by a single radiologist, using an ATL HDI 5000 ultrasound machine (ATL, Boswell). The images were analysed using a specially developed software package (HDI Lab), which quantifies power Doppler signal. All patients improved clinically following treatment, which was reflected in functional disability scores, and in the C-reactive protein levels and erythrocyte sedimentation rate. In all cases, there was a significant decrease in synovial vascularity as measured by the mean amplitude of signal on quantitative power Doppler. Quantitative power Doppler may allow objective assessment of treatment in small joint synovitis.

The therapeutic potential of TNF-alpha blockade in rheumatoid arthritis

Rheumatoid arthritis is a chronic autoimmune disease characterised by inflammation of the synovial lining of joints and destruction of cartilage and bone. Many pro-inflammatory cytokines, chemokines and growth factors are expressed in diseased joints, and recognition of the key role of TNF-alpha led to the development of highly effective new therapies. TNF-alpha inhibitors, such as monoclonal anti-TNF-alpha antibody infliximab (Remicade), have demonstrated efficacy in clinical trials. It is now clear that TNF-alpha blockade, in addition to reducing joint inflammation and leukocyte infiltration, also results in decreased formation of new blood vessels in the synovium. Such mechanism of action studies are now paving the way for the development of the next generation of drugs for treatment of rheumatoid arthritis.

Vascular endothelial growth factor in children with congenital heart disease

BACKGROUND

Children with cyanotic congenital heart disease may experience the development of abnormal vessels that become a source of significant morbidity. Abnormal vessel proliferation in these children may take several forms, including systemic-to-pulmonary collateral arteries, systemic-to-pulmonary venous collaterals, systemic venous collateral channels after bidirectional cavopulmonary anastomosis, and pulmonary arteriovenous malformations. However, no entity responsible for these abnormalities has been identified yet. This study determined whether children with cyanotic congenital heart disease have elevated serum levels of vascular endothelial growth factor (VEGF) and whether elevated VEGF correlated with these abnormal vessels.

METHODS

Mean systemic room air oxygen saturation (SpO2), blood cell counts (RBC), and serum VEGF levels were measured preoperatively. Samples were obtained from 61 children with acyanotic heart disease (group N) and 102 children with cyanotic heart disease (group C) before cardiac surgery. Postoperative catheterization was performed 1-month after the operation to evaluate the abnormal vessels in group C.

RESULTS

The VEGF level was significantly elevated in group C (355.0 +/- 287.1 pg/mL) compared with group N (203.0 +/- 221.6 pg/mL; p < 0.001). VEGF levels in patients with a single ventricle associated with asplenia syndrome (n = 7) in group C were significantly elevated (711.9 +/- 443.5 pg/mL) compared with other patients. There was no significant correlation between VEGF level and SpO2 or RBC. Abnormal vessels were diagnosed in 19.6% (20/102) patients in group C. There was no difference in VEGF levels between the patients with abnormal vessels (336.8 +/- 182.5 pg/mL) and the patients without abnormal vessels (359.1 +/- 306.8 pg/mL).

CONCLUSIONS

Children with cyanotic heart disease have elevated systemic levels of VEGF, especially in those patients with a single ventricle associated with asplenia syndrome. There was no significant relationship in VEGF levels between the patients with abnormal vessels and without these vessels.

High serum vascular endothelial growth factor correlates with disease activity of spondylarthropathies

Angiogenesis is involved in chronic inflammatory joint diseases such as rheumatoid arthritis (RA). Vascular endothelial growth factor (VEGF) plays a crucial role in angiogenesis. The spondylarthropathies (SpA) are characterized by enthesitis and synovitis, in which blood vessels participate. The objective of this study was to investigate serum VEGF levels and their potential associations with disease activity markers for SpA. Sera were collected from 105 patients with SpA (72 with ankylosing spondylitis (AS), four with psoriatic arthritis (PsA), six with reactive arthritis (ReA), eight with enteropathic arthropathy and 15 with undifferentiated SpA), 50 patients with rheumatoid arthritis (RA) and 64 healthy controls. Disease activity in SpA patients was assessed using the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and laboratory parameters of inflammation [erythrocyte sedimentation rate (ESR) and C-reactive protein level (CRP)]. Serum VEGF levels were significantly higher in SpA patients (316.4 +/- 215.6 pg/ml) and RA patients (405.2 +/- 366.5) than in controls (217.3 +/- 145.2) (P = 0.003). In SpA patients, serum VEGF levels correlated with disease activity indices (BASDAI: r = 0.22, P = 0.04; ESR: r = 0.3, P = 0.003; and CRP: r = 0.23, P = 0.02). Serum VEGF levels were not associated with presence of extra-articular manifestations or syndesmophytes or with the grade of sacroiliitis. These results suggest that VEGF and therefore angiogenesis may play a role in SpA pathogenesis and may serve as a disease activity marker in SpAs.

The angiogenesis inhibitor protease-activated kringles 1-5 reduces the severity of murine collagen-induced arthritis

During rheumatoid arthritis there is enlargement and increased cellularity of the synovial lining of joints, before invasion by the synovium of the underlying cartilage and bone. This increased tissue mass requires a network of blood vessels to supply nutrients and oxygen. Disruption of synovial angiogenesis is thus a desirable aim of antiarthritic therapies. Protease-activated kringles 1-5 (K1-5) is an angiogenesis inhibitor related to angiostatin. In common with angiostatin, K1-5 contains the first four kringle domains of plasminogen, but also encompasses the kringle 5 domain, which confers enhanced antiangiogenic activity when compared with angiostatin. The purpose of the present study was to assess the effect on murine arthritis of K1-5. Arthritis was induced in DBA/1 mice by a single injection of bovine collagen. Treatment with K1-5 was commenced on the day of arthritis onset and continued for 10 days, until the end of the experiment. Daily intraperitoneal administration of K1-5 (2 mg/kg body weight) significantly reduced both paw swelling and clinical score (a composite index of the number of arthritic limbs and the severity of disease). The clinical efficacy of this treatment was reflected by a reduction in joint inflammation and destruction, as assessed histologically. These data suggest that antiangiogenic therapies, which block formation of new blood vessels and hence reduce synovial expansion, might be effective in treating rheumatoid arthritis.

Angiogenesis in the female reproductive organs: pathological implications

The female reproductive organs (ovary, uterus, and placenta) are some of the few adult tissues that exhibit regular intervals of rapid growth. They also are highly vascular and have high rates of blood flow. Angiogenesis, or vascular growth, is therefore an important component of the growth and function of these tissues. As with many other tissues, vascular endothelial growth factors (VEGFs) and fibroblast growth factors (FGFs) appear to be major angiogenic factors in the female reproductive organs. A variety of pathologies of the female reproductive organs are associated with disturbances of the angiogenic process, including dysfunctional uterine bleeding, endometrial hyperplasia and carcinoma, endometriosis, failed implantation and subnormal foetal growth, myometrial fibroids (uterine leiomyomas) and adenomyosis, ovarian hyperstimulation syndrome, ovarian carcinoma, and polycystic ovary syndrome. These pathologies are also associated with altered expression of VEGFs and/or FGFs. In the near future, angiogenic or antiangiogenic compounds may prove to be effective therapeutic agents for treating these pathologies. In addition, monitoring of angiogenesis or angiogenic factor expression may provide a means of assessing the efficacy of these therapies.

Angiogenesis in rheumatoid arthritis

The expansion of the synovial lining of joints in rheumatoid arthritis (RA) and the subsequent invasion by the pannus of underlying cartilage and bone necessitate an increase in the vascular supply to the synovium, to cope with the increased requirement for oxygen and nutrients. The formation of new blood vessels - termed 'angiogenesis' - is now recognised as a key event in the formation and maintenance of the pannus in RA. This pannus is highly vascularised, suggesting that targeting blood vessels in RA may be an effective future therapeutic strategy. Disruption of the formation of new blood vessels would not only prevent delivery of nutrients to the inflammatory site, but could also lead to vessel regression and possibly reversal of disease. Although many proangiogenic factors are expressed in the synovium in RA, the potent proangiogenic cytokine vascular endothelial growth factor (VEGF) has been shown to a have a central involvement in the angiogenic process in RA. The additional activity of VEGF as a vascular permeability factor may also increase oedema and hence joint swelling in RA. Several studies have shown that targeting angiogenesis in animal models of arthritis ameliorates disease. Our own study showed that inhibition of VEGF activity in murine collagen-induced arthritis, using a soluble VEGF receptor, reduced disease severity, paw swelling, and joint destruction. Although no clinical trials of anti-angiogenic therapy in RA have been reported to date, the blockade of angiogenesis - and especially of VEGF - appears to be a promising avenue for the future treatment of RA.

Does a pro-angiogenic state exist in the bone-implant interface of aseptically loosened joint prosthesis?

Neovascularization is indispensable to both bone remodeling and the development of chronic inflammation. A pro-angiogenic state in the periprosthetic tissue may augment the inflammatory response to wear debris. To investigate if a pro-angiogenic state exists in the bone-implant interface of aseptically loosened joint prosthesis, the expression of vascular endothelial growth factor (VEGF) and its receptor Flk-1/KDR were studied by immunohistochemistry. The VEGF-Flk/KDR pathway has been implicated as a key signaling requirement for pathological angiogenesis. The level of vascularization in periprosthetic tissue was semi-quantitatively compared to osteoarthritic (OA) and rheumatoid arthritic (RA) synovium. The level of vascularization in areas of periprosthetic tissue with heavy or low/moderate wear debris were also compared semi-quantitatively by image analysis. High levels of VEGF expression (16/16 cases) particularly in the implant synovial-like lining layer together with Flk-1/KDR expression by endothelial cells (13/16), suggests that neovascularization is occurring. Morphometric comparison of periprosthetic tissue with RA and OA synovium revealed no significant difference in microvessel density, but did reveal significantly increased microvessel area in RA synovium (P > 0.05). Areas of high wear debris infiltrate also contained a significantly smaller microvessel area (P > 0.01). Suggesting that wear debris may cause behavioral modification of microvessels. Modifying angiogenesis in the periprosthetic tissue could be a potential therapeutic target in reducing inflammation.

Raised serum vascular endothelial growth factor levels are associated with destructive change in inflammatory arthritis

OBJECTIVE

To determine whether elevated levels of the angiogenic cytokine vascular endothelial growth factor (VEGF), detected on presentation to an early arthritis clinic, are associated with the development of chronic and erosive arthritis.

METHODS

Concentrations of VEGF and its soluble receptor, soluble fms-like tyrosine kinase 1 (sFlt-1), were measured by enzyme-linked immunosorbent assay in serum samples from patients with early (<2 years from onset) arthritic symptoms in the peripheral joints, namely early rheumatoid arthritis (RA), self-limiting arthritis (viral, reactive, and idiopathic inflammatory arthritis), or psoriatic arthritis. In addition, measurements were made in random samples from patients with longstanding (>3 years from symptom onset) RA treated with disease-modifying antirheumatic drugs, from patients with osteoarthritis (OA), and from patients with polyarthralgia without arthritis, as well as from nonarthritic controls.

RESULTS

Serum VEGF levels at presentation were elevated in patients with inflammatory arthritis (RA, psoriatic, and self-limiting arthritis) as well as in patients with OA, in comparison with nonarthritic controls. Moreover, serum VEGF concentrations were significantly higher in patients with early RA than in patients with self-limiting arthritis. Serum VEGF levels at presentation in patients with early RA correlated significantly with the development of radiographic damage after 1 year. Improvement in the clinical symptoms of RA was associated with a reduction in serum VEGF levels. Serum sFlt-1 levels were raised in patients with early and longstanding RA and in those with self-limiting arthritis, and correlated positively with the serum VEGF concentrations in patients with inflammatory arthritis.

CONCLUSION

These findings implicate the proangiogenic cytokine VEGF in the persistence of inflammatory arthritis, and support the hypothesis that expansion of the synovial vasculature is important for the development of joint destruction in RA.

Ultrastructural response of pulmonary intravascular macrophages to exogenous oestrogen in the bovine lung: translocation of the surface-coat and enhanced cell membrane plasticity and angiogenesis

The pulmonary intravascular macrophages (PIMs) of domestic ungulates are recognised by their specific surface coat, consisting of linearly arranged globules along the external leaf of the plasma membrane. The coat is sensitive to in vitro digestion with lipolytic lipase (LPL), intravenous heparin and clinical exposure to halothane anaesthesia. The sensitivity to these experimental manipulations suggests that the globules of the coat are predominantly composed of lipoproteins (LDL). The present administration of oestradiol proprionate in castrated male calves potentiated the translocation of the surface coat into the endocytotic pathway of the PIMs. Concurrently with mobilisation of the coat, the plasma membrane was thrown into prominent arrays of lamellipodial extensions. The sprawling macrophages made extensive adhesive contacts with the lining endothelium of the capillaries. Consequently, the endothelial cells were highly attenuated and precariously maintained the integrity of the vascular wall. At some focal points, the vascular wall was penetrated by the filopodial processes of PIMs, which protruded into the perivascular space. Furthermore, there were signs of neovascularisation in the form of overt mitotic changes, sprouting and precursor capillary formation. It is conceivable that the evolving profile of angiogenesis is due to the vascular endothelial growth factor (VEGF) paracrine function of PIMs. Endothelial cell specificity has been considered an important advantage of VEGF for neovascularisation. It allows pleotrophic response of endothelial cells to proliferate and to assemble into endothelial tubes.

Expression of angiogenic factors in juvenile rheumatoid arthritis: correlation with revascularization of human synovium engrafted into SCID mice

OBJECTIVE

Although increased vascularity was noted in early histopathologic studies of juvenile rheumatoid arthritis (JRA) synovium, the available data on angiogenesis in JRA are very limited. The main purposes of this study were to assess expression of the key angiogenic factors in JRA synovium, and to evaluate a SCID mouse model of JRA as an approach to study in vivo regulation of the expression of these factors in JRA.

METHODS

RNase protection assay was used to assess the expression of the key angiogenic factors in fresh JRA synovium and in JRA synovial tissue fragments that had been minced and then implanted into SCID mice. Vascularity of the samples was assessed by immunohistochemical staining for von Willebrand factor. Synovial specimens obtained from patients with osteoarthritis (OA) or other noninflammatory arthropathies were used as controls.

RESULTS

Detectable levels of messenger RNA for vascular endothelial growth factor and angiopoietin 1 and their respective receptors, as well as endoglin and thrombin receptors, were present in all JRA tissue specimens studied. The levels of expression of these factors in JRA tissues were significantly higher than those in tissues obtained from patients with OA or other noninflammatory arthropathies. Furthermore, increased expression of the key angiogenic factors in the fresh JRA tissues correlated with the exuberant revascularization of JRA minced tissue fragments implanted into SCID mice. This was in sharp contrast to the poor revascularization of implanted OA tissues.

CONCLUSION

JRA synovium is characterized by high angiogenic activity. SCID mouse-human JRA synovium chimeras may provide a good approach to study the in vivo regulation of angiogenesis in JRA.

Local interaction simulation approach for the response of the vascular system to metabolic changes of cell behavior

The self-regulatory interactions between cells and the vascular system are mediated by signals propagating at a finite speed. In order to build up a physical model of these processes, several features, such as storing of internal energy, nonclassical nonlinear behavior, and delay and threshold effects, have to be taken into account. Considering cells as particles in different metabolic states according to their internal energy, we have developed a model based on the local interaction simulation approach. Several numerical results, in qualitative agreement with biological observations, illustrate the applicability of the model and the method to implement it.