Vascular endothelial growth factor (VEGF) in Crohn's disease: increased production by peripheral blood mononuclear cells and decreased VEGF165 labeling of peripheral CD14+ monocytes

VEGF-A from Granuloma Macrophages Regulates Granulomatous Inflammation by a Non-angiogenic Pathway during Mycobacterial Infection

Many autoimmune and infectious diseases are characterized by the formation of granulomas which are inflammatory lesions that consist of spatially organized immune cells. These sites protect the host and control pathogens like Mycobacterium tuberculosis (Mtb), but are highly inflammatory and cause pathology. Using bacille Calmette-Guerin (BCG) and Mtb infection in mice that induce sarcoid or caseating granulomas, we show that a subpopulation of granuloma macrophages produces vascular endothelial growth factor (VEGF-A), which recruits immune cells to the granuloma by a non-angiogenic pathway. Selective blockade of VEGF-A in myeloid cells, combined with granuloma transplantation, shows that granuloma VEGF-A regulates granulomatous inflammation. The severity of granuloma-related inflammation can be ameliorated by pharmaceutical or genetic inhibition of VEGF-A, which improves survival of mice infected with virulent Mtb without altering host protection. These data show that VEGF-A inhibitors could be used as a host-directed therapy against granulomatous diseases like tuberculosis and sarcoidosis, thereby expanding the value of already existing and approved anti-VEGF-A drugs.

Vascular endothelial growth factor, endostatin levels and clinical features among patients with ulcerative colitis and irritable bowel syndrome and among healthy controls: a cross-sectional analytical study

BACKGROUND

Increased angiogenetic activity in inflammatory bowel disease (IBD) has been shown in previous studies. The aim of this study was to evaluate the relationship of serum vascular endothelial growth factor (VEGF) and endostatin levels with clinical features and mucosal expression in patients with ulcerative colitis (UC).

DESIGN AND SETTING

Cross-sectional analytical study conducted in a tertiary-level public hospital.

METHODS

Serum VEGF and endostatin levels were determined in 82 individuals: 39 with UC, 28 with irritable bowel syndrome (IBS) and 15 healthy controls (HCs), using enzyme-linked immunosorbent assays (ELISA). VEGF and endostatin expressions were studied using immunohistochemistry (IHC).

RESULTS

Mean serum VEGF and endostatin levels were significantly higher in patients with UC than in patients with IBS and in HCs (511.9 ± 377.5 pg/ml, 305.0 ± 121.42 pg/ml and 36.1 ± 40.6 pg/ml; P = 0.001 for VEGF; and 155.50 ± 59.8 ng/ml, 116.9 ± 23.8 ng/ml and 102.2 ± 22.4 ng/ml; P < 0.001 for endostatin, respectively). There was a positive correlation between serum VEGF and endostatin levels (r = 0.422; P < 0.01). Mean H-scores for VEGF expression were higher in the active UC group than in the inactive UC and IBS groups, in the stroma, endothelium and epithelium. Mean H-scores for endostatin expression were higher in the active UC group than in the inactive UC and IBS groups, in the stroma and endothelium. There was no endostatin expression in the epithelium.

CONCLUSION

Increased endostatin appears to be a defensive reaction to increased VEGF in patients with UC.

Mechanisms of angiogenesis in microbe-regulated inflammatory and neoplastic conditions

Commensal microbiota inhabit all the mucosal surfaces of the human body. It plays significant roles during homeostatic conditions, and perturbations in numbers and/or products are associated with several pathological disorders. Angiogenesis, the process of new vessel formation, promotes embryonic development and critically modulates several biological processes during adulthood. Indeed, deregulated angiogenesis can induce or augment several pathological conditions. Accumulating evidence has implicated the angiogenic process in various microbiota-associated human diseases. Herein, we critically review diseases that are regulated by microbiota and are affected by angiogenesis, aiming to provide a broad understanding of how angiogenesis is involved and how microbiota regulate angiogenesis in microbiota-associated human conditions.

A zebrafish model of inflammatory lymphangiogenesis

Inflammatory bowel disease (IBD) is a disabling chronic inflammatory disease of the gastrointestinal tract. IBD patients have increased intestinal lymphatic vessel density and recent studies have shown that this may contribute to the resolution of IBD. However, the molecular mechanisms involved in IBD-associated lymphangiogenesis are still unclear. In this study, we established a novel inflammatory lymphangiogenesis model in zebrafish larvae involving colitogenic challenge stimulated by exposure to 2,4,6-trinitrobenzenesulfonic acid (TNBS) or dextran sodium sulphate (DSS). Treatment with either TNBS or DSS resulted in vascular endothelial growth factor receptor (Vegfr)-dependent lymphangiogenesis in the zebrafish intestine. Reduction of intestinal inflammation by the administration of the IBD therapeutic, 5-aminosalicylic acid, reduced intestinal lymphatic expansion. Zebrafish macrophages express vascular growth factors vegfaa, vegfc and vegfd and chemical ablation of these cells inhibits intestinal lymphatic expansion, suggesting that the recruitment of macrophages to the intestine upon colitogenic challenge is required for intestinal inflammatory lymphangiogenesis. Importantly, this study highlights the potential of zebrafish as an inflammatory lymphangiogenesis model that can be used to investigate the role and mechanism of lymphangiogenesis in inflammatory diseases such as IBD.

Characterization of Serum Cytokine Profile in Predominantly Colonic Inflammatory Bowel Disease to Delineate Ulcerative and Crohn's Colitides

BACKGROUND

As accessible diagnostic approaches fail to differentiate between ulcerative colitis (UC) and Crohn’s colitis (CC) in one-third of patients with predominantly colonic inflammatory bowel disease (IBD), leading to inappropriate therapy, we aim to investigate the serum cytokine levels in these patients in search of molecular biometric markers delineating UC from CC.

METHODS

We measured 38 cytokines, chemokines, and growth factors using magnetic-bead-based multiplex immunoassay in 25 UC patients, 28 CC patients, and 30 controls. Our results are compared with those from a review of current literature regarding advances in serum cytokine profiles and associated challenges preventing their use for diagnostic/prognostic purposes.

RESULTS

Univariate analysis showed statistically significant increases of eotaxin, GRO, and TNF-α in UC patients compared to controls (Ctrl); interferon γ, interleukin (IL)-6, and IL-7 in CC group compared to Ctrl; and IL-8 in both UC and CC versus Ctrl. No cytokines were found to be different between UC and CC. A generalized linear model identified combinations of cytokines, allowing the identification of UC and CC patients, with area under the curve (AUC) = 0.936, as determined with receiver operating characteristic (ROC) analysis.

CONCLUSIONS

The current knowledge available about circulating cytokines in IBD is often contradictory. The development of an evidence-based tool using cytokines for diagnostic accuracy is still preliminary.

Relationship between levels of angiogenic and lymphangiogenic factors and the endoscopic, histological and clinical activity, and acute-phase reactants in patients with inflammatory bowel disease

BACKGROUND

Angiogenic and lymphangiogenic factors (ALFs) may play an important role in inflammatory bowel disease (IBD). Our aims were to evaluate levels of ALFs in serum and the colonic mucosa culture supernatant (MCS) of patients with active and quiescent IBD and healthy subjects and to correlate them with the endoscopic, clinical and histological activity and with acute-phase reactants.

METHODS

This is a prospective study of 28 controls and 72 IBD patients. Serum and MCS concentration of VEGFA, VEGFC, VEGFD, VEGFR1, VEGFR2, VEGFR3, PlGF, Ang1, Ang2 and Tie2 were measured by ELISA. Activity was established by specific indexes (CDAI, Mayo score, SES-CD, D'Haens scale and Riley index). Acute-phase reactants were routinely measured.

RESULTS

MCS levels of all ALFs except VEGFR3 were higher in patients with endoscopic (p<0.05), clinical (p<0.05) and histological (p<0.01) activity than in those without it. In serum, VEGFA, VEGFC and Ang1 and VEGFA and Ang1 levels were lower in patients in remission than in patients with clinical and histological activity, respectively (p<0.05). There was a correlation between serum and MCS concentrations for VEGFD, VEGFR3, PlGF and Tie2 (r=0.25, r=0.48, r=-0.45 and r=0.36; p<0.05). Ang2 in MCS was the best predictor for the diagnosis of endoscopic, histological and clinical activity (area under ROC curve>0.8).

CONCLUSIONS

MCS determination suggests a local increase in ALFs that correlates with IBD activity. Although the correlation between ALFs in serum and MCS was not good, the study of some of these factors as possible targets of new drugs for IBD constitutes a key new line of research.

Role of growth factors in the development of lymphangiogenesis driven by inflammatory bowel disease: a review

Studies on angiogenesis and lymphangiogenesis have gained special relevance in research into factors potentially influencing the pathogenesis and course of inflammatory bowel disease (IBD). The results of the few existing studies on the distribution and density of lymphatic vessels and blood vessels in the context of IBD are controversial. Studies using the specific lymphatic marker podoplanin have revealed a significantly large number of lymphatic vessels in the colonic mucosa of patients with ulcerative colitis and Crohn's disease (compared to patients with normal mucosa), whereas other authors have found no significant differences. However, the role of vascular endothelial growth factor (VEGF) tyrosine-kinase receptor 3 (VEGFR-3) in the onset of IBD has not been analyzed. In recent years new biochemical, molecular, and immunohistochemical studies indicate that several families of growth factors, such as the VEGF family and their receptors, fibroblast growth factor-2, platelet-derived growth factor-BB, hepatocyte growth factor, the angiopoietin system, and integrins may play an important role in the onset of IBD. To date, no comparative studies have analyzed these growth factors and specific lymphatic markers. We examine how growth factors are involved in the development of pathological lymphangiogenesis in patients with IBD and determine whether they play a crucial role in disease exacerbation.

VEGF₁₆₄ isoform specific regulation of T-cell-dependent experimental colitis in mice

BACKGROUND

Inflammatory bowel disease (IBD) consists of Crohn's disease (CD) and ulcerative colitis (UC), two widespread diseases of unknown, multifactorial etiology. Colitis pathology involves a pathological angiogenic response where increases in vascular density participate in colitis histopathology. Vascular endothelial growth factor-A (VEGF-A) is a potent angiogenesis stimulator known to be involved in pathological angiogenesis in several diseases including colitis. However, the pathogenic importance of specific VEGF-A isoforms during T-cell-mediated experimental colitis remains largely unknown.

METHODS

The CD4⁺ CD45RB(high) T-cell transfer model of experimental colitis was used for these studies. The VEGF lac-Z transgenic reporter mouse was used to examine specific cellular sources of VEGF-A production. The VEGF₁₆₄ aptamer (Macugen), adenoviral VEGF₁₆₄, and the VEGF Trap were used to evaluate pathological importance.

RESULTS

VEGF lac-Z reporter mice experiments showed that both infiltrating T cells and local tissue cells produce VEGF-A in the colon during disease. Inhibition of VEGF₁₆₄ using a highly selective RNA aptamer significantly attenuated CD4⁺ CD45RB(high) T-cell-dependent experimental colitis by reducing pathological angiogenesis and inflammatory pathology. Conversely, broad-spectrum VEGF inhibition with VEGF Trap did not attenuate disease, nor did adenoviral VEGF₁₆₄ overexpression significantly alter colitis pathology.

CONCLUSIONS

VEGF₁₆₄ is actively produced by multiple cell types during T-cell-mediated colitis. Importantly, specific inhibition of the VEGF₁₆₄ isoform during T-cell-mediated colitis dose-dependently attenuated disease progression, while broad-scale inhibition of all VEGF-A isoforms was not therapeutically beneficial.

Angiogenesis in inflammatory bowel disease

Both ulcerative colitis and Crohn's disease, the two major forms of inflammatory bowel diseases, are recognized, at the moment, as perplexing and challenging clinical entities, in which several molecules and cell types are implicated. Recent molecular evidence proposes the intestinal microvascular remodelling or angiogenesis, as a phenomenon implicated in the pathogenesis of these chronic inflammatory disorders, together with other proposed theories involved in the pathogenesis of inflammatory bowel diseases, such as genetic, microbacterial and immune factors. Intestinal damage is followed by a physiological angiogenesis, but the abnormal expression of pro- and anti-angiogenic molecules and the changes of vascular cell types could reflect a pathological vascular remodelling. Thus, the inflammation may be favoured and maintained by a pathological angiogenesis. A better understanding of the angiogenic process may facilitate the design of more effective therapies for chronic intestinal inflammation.

Up-regulation of intestinal vascular endothelial growth factor by Afa/Dr diffusely adhering Escherichia coli

BACKGROUND

Angiogenesis has been recently described as a novel component of inflammatory bowel disease pathogenesis. The level of vascular endothelial growth factor (VEGF) has been found increased in Crohn's disease and ulcerative colitis mucosa. To question whether a pro-inflammatory Escherichia coli could regulate the expression of VEGF in human intestinal epithelial cells, we examine the response of cultured human colonic T84 cells to infection by E. coli strain C1845 that belongs to the typical Afa/Dr diffusely adhering E. coli family (Afa/Dr DAEC).

METHODOLOGY

VEGF mRNA expression was examined by Northern blotting and q-PCR. VEGF protein levels were assayed by ELISA and its bioactivity was analysed in endothelial cells. The bacterial factor involved in VEGF induction was identified using recombinant E. coli expressing Dr adhesin, purified Dr adhesin and lipopolysaccharide. The signaling pathway activated for the up-regulation of VEGF was identified using a blocking monoclonal anti-DAF antibody, Western blot analysis and specific pharmacological inhibitors.

PRINCIPAL FINDINGS

C1845 bacteria induce the production of VEGF protein which is bioactive. VEGF is induced by adhering C1845 in both a time- and bacteria concentration-dependent manner. This phenomenon is not cell line dependent since we reproduced this observation in intestinal LS174, Caco2/TC7 and INT407 cells. Up-regulation of VEGF production requires: (1) the interaction of the bacterial F1845 adhesin with the brush border-associated decay accelerating factor (DAF, CD55) acting as a bacterial receptor, and (2) the activation of a Src protein kinase upstream of the activation of the Erk and Akt signaling pathways.

CONCLUSIONS

Results demonstrate that a Afa/Dr DAEC strain induces an adhesin-dependent activation of DAF signaling that leads to the up-regulation of bioactive VEGF in cultured human intestinal cells. Thus, these results suggest a link between an entero-adherent, pro-inflammatory E. coli strain and angiogenesis which appeared recently as a novel component of IBD pathogenesis.

Pathogenic angiogenesis in IBD and experimental colitis: new ideas and therapeutic avenues

Angiogenesis is now understood to play a major role in the pathology of chronic inflammatory diseases and is indicated to exacerbate disease pathology. Recent evidence shows that angiogenesis is crucial during inflammatory bowel disease (IBD) and in experimental models of colitis. Examination of the relationship between angiogenesis and inflammation in experimental colitis shows that initiating factors for these responses simultaneously increase as disease progresses and correlate in magnitude. Recent studies show that inhibition of the inflammatory response attenuates angiogenesis to a similar degree and, importantly, that inhibition of angiogenesis does the same to inflammation. Recent data provide evidence that differential regulation of the angiogenic mediators involved in IBD-associated chronic inflammation is the root of this pathological angiogenesis. Many factors are involved in this phenomenon, including growth factors/cytokines, chemokines, adhesion molecules, integrins, matrix-associated molecules, and signaling targets. These factors are produced by various vascular, inflammatory, and immune cell types that are involved in IBD pathology. Moreover, recent studies provide evidence that antiangiogenic therapy is a novel and effective approach for IBD treatment. Here we review the role of pathological angiogenesis during IBD and experimental colitis and discuss the therapeutic avenues this recent knowledge has revealed.

The role of vascular endothelial growth factor (VEGF) in inflammatory bowel disease

BACKGROUND

Vascular endothelial growth factor (VEGF) is a candidate susceptibility gene to inflammatory bowel disease (IBD), both from a functional as well as genetic perspective. Moreover, serum VEGF (sVEGF) levels are increased in IBD and correlate with disease activity. Both VEGF expression and sVEGF levels may be influenced by VEGF gene polymorphisms.

AIMS

To study VEGF polymorphisms in IBD susceptibility and their impact on sVEGF levels.

METHODS

Four functional VEGF polymorphisms (-C2578A, -G1154A, -G634C, and C936T) were genotyped in two independent cohorts (cohort 1: 372 IBD trios; cohort 2: 452 unrelated IBD patients, 271 healthy controls [HC]; and 93 patients with non-IBD gastrointestinal inflammation [non-IBD GI]), using polymerase chain reaction with restriction fragment length polymorphism and TaqMan minor groove binding. Phenotypical data on all patients as well as sVEGF levels were correlated with the genetic data.

RESULTS

Both the VEGF genotype and haplotype frequencies did not differ between IBD patients and controls, and no distortion of transmission was observed. sVEGF levels were increased in IBD but also in non-IBD GI patients, compared with HC, and were only influenced by VEGF polymorphisms in patients with Crohn's disease (-G1154A genotype and -2578/-1154/-634 AAG promoter haplotype).

CONCLUSIONS

The VEGF polymorphisms studied are not implicated in susceptibility to IBD and do not predict sVEGF levels. Although increased sVEGF and angiogenesis are important features of IBD, they do not appear genetically determined.

Angiogenesis--a new target for future therapy

Development of blood vessels from in situ differentiating endothelial cells (EC) is called vasculogenesis, whereas sprouting of new blood vessels from the pre-existing ones is termed angiogenesis or neovascularisation. Angiogenesis, the growth of new blood vessels, is essential during tissue repair, foetal development, and female reproductive cycle. In contrast, uncontrolled angiogenesis promotes tumor and retinopathies, while inadequate angiogenesis can lead to coronary artery disease. A balance between pro-angiogenic and anti-angiogenic growth factors and cytokines tightly controls angiogenesis. With the identification of several proangiogenic molecules such as the vascular endothelial cell growth factor (VEGF), the fibroblast growth factors (FGFs), and the angiopoietins, and the recent description of specific inhibitors of angiogenesis such as platelet factor-4, angiostatin, endostatin, and vasostatin, it is recognized that therapeutic interference with vasculature formation offers a tool for clinical applications in various pathologies. Inhibition of angiogenesis can prevent diseases such as cancer, diabetic nephropathy, arthritis, psoriasis, whereas stimulation of angiogenesis is beneficial in the treatment of coronary artery disease (CAD), cardiac failure, tissue injury, etc. One of the most specific and critical regulators of angiogenesis is vascular endothelial growth factor (VEGF), which regulates endothelial proliferation, permeability, and survival. Substantial evidence also implicates VEGF as an angiogenic mediator in tumors and intraocular neovascular syndromes, and numerous clinical trials are presently testing the hypothesis that inhibition of VEGF may have therapeutic value.

Oligonucleotides used as template calibrators for general application in quantitative polymerase chain reaction

The optimizing and controlling for polymerase chain reactions (PCRs) requires standard target sequences to measure reaction specificity and to obtain accurate gene quantification. However, defined target sequences are often not readily available. This situation is particularly evident in the study of rare splice variant transcripts. For gains in efficiency and reaction speed, a small size of PCR amplicon typifies real-time PCR formats, including hydrolysis probes. This study demonstrates the use of oligonucleotides resembling one strand of complete amplicon sequences used in real-time PCR to provide sustainable and precise amounts of the target sequence without the necessity of enlisting nucleic acid cloning procedures. The application of template oligonucleotides is modeled using all of the splice variant forms of human vascular endothelial growth factor.

The role of vascular endothelial growth factor in wound healing

Revascularization of damaged tissue is a necessary part of wound healing. With unregulated or insufficient vessel growth, healing is delayed or pathological. Angiogenesis is regulated by expression of a variety of vascular growth factors and modulators, the most widely expressed and critical of which is vascular endothelial growth factor (VEGF). This protein is secreted by tissues in response to ischemic and inflammatory stimuli and results in endothelial migration, proliferation, and increased vascular permeability. The regulation of VEGF expression during wound healing is of considerable importance since angiogenesis appears to be disturbed in abnormally healing wounds. This paper describes the current state of knowledge of VEGF expression in wounds, regulation of expression, control of isoform specificity, and the effects of VEGF expression on blood vessels as they grow in wound healing, as understood from many different pathological paradigms.

Serum bFGF and VEGF correlate respectively with bowel wall thickness and intramural blood flow in Crohn's disease

Serum levels of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF)--two factors known to promote tissue repair, fibroblast proliferation, and angiogenesis--were measured in Crohn's disease patients and correlated with bowel wall thickness (BWT), measured by conventional grey scale ultrasonography, and with the ileal intramural vessel flow, measured by contrast-enhanced color Doppler imaging. Serum samples were obtained from 25 patients with active Crohn's disease and 22 healthy volunteers, all sex- and age-matched. Serum bFGF and VEGF levels were measured by ELISA assay. All the patients were examined with conventional transabdominal bowel sonography. Color Doppler of the intramural enteric vessels was then performed after the intravenous injection of Levovist, a galactose-based sonographic contrast agent. In Crohn's disease patients, serum bFGF and VEGF were significantly higher compared with healthy volunteers. A positive correlation between serum bFGF and BWT and between serum VEGF and color Doppler signal intensity was found. The raised serum bFGF levels in Crohn's disease patients with intestinal strictures compared with patients with other phenotypes (fistulizing, inflammatory), together with the correlation observed between serum bFGF and BWT, suggests a possible involvement of bFGF in the process of transmural fibrogenesis in Crohn's disease. The higher levels of VEGF in those patients with increased intramural blood flow suggests that VEGF may be considered a marker of angiogenesis in this condition.

Elevated levels of vascular endothelial growth factor in serum of patients with D+ HUS

The pathogenesis of hemolytic uremic syndrome (D+ HUS) is characterized by endothelial damage of glomeruli and tubules within the kidney. In several other diseases in which glomerular endothelial damage occurs, elevated serum levels of vascular endothelial growth factor (VEGF) have been reported. VEGF is involved in angiogenesis, permeabilization of blood vessel endothelium, and wound repair. In this study we evaluated VEGF levels in the serum of 40 D+ HUS patients in the acute phase and during the course of the disease. VEGF levels were measured using a double-sandwich ELISA. Indirect immunohistochemistry was performed for the detection of VEGF in renal biopsy material of 3 HUS patients. Significantly elevated VEGF levels were found in HUS patients compared with controls in both serum ( P<0.001) and plasma ( P<0.05). A significant relationship was found between VEGF levels and severity of the disease according to the classification of Gianantonio ( P<0.05). Levels of VEGF in blood increased during the 2nd and 3rd week after HUS was diagnosed. Immunohistochemistry of renal biopsy material showed increased levels of the receptors for VEGF in the glomeruli. During the course of HUS, plasma VEGF levels increase and the increase is dependent on the severity of the disease. This is probably associated with the repair process.

Microangiopathy of Split-Skin Grafts in Venous Ulcers

BACKGROUND

In patients with chronic venous insufficiency, microangiopathy of blood and lymph capillaries caused by venous hypertension plays a major role in the development of venous ulceration. Conservative treatment of venous leg ulcers often fails, and split-skin grafting is sometimes performed.

OBJECTIVE

To evaluate the microcirculation and especially the regeneration and function of lymphatic vessels in skin grafts in patients with chronic venous insufficiency.

METHODS

The microcirculation of 15 split-skin grafts was studied by fluorescence microlymphography and measurement of transcutaneous oxygen tension (tcpO2) in 13 patients.

RESULTS

The mean age of the skin grafts was 70.9 months. In only two skin grafts were a few intact lymph meshes found. In all other cases, only fragments of lymphatic capillaries have been detected. In seven skin grafts, cutaneous backflow of dye through insufficient deeper lymph channels was observed. The maximal spread of the dye in the lymphatic network was increased in the skin grafts (17.6 +/- 22.9 mm). The mean value of tcpO2 was only 27.1 +/- 18.1 mm Hg.

CONCLUSIONS

In split-skin grafts of patients with venous ulcers, severe microcirculatory changes are present and characterized by hypoxia and abnormal regeneration and function of lymphatic vessels.

Increased vascular endothelial growth factor production in fibroblasts isolated from strictures in patients with Crohn's disease

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that is implicated in early wound healing and fibrosis. Fibroblasts may initiate stricture formation in Crohn's disease through overexpression of VEGF. The aim of this study was to examine VEGF expression and regulation in fibroblasts isolated from patients with Crohn's disease.

METHODS

Fibroblasts were isolated by a primary explant technique from serosal biopsies of non-strictured and strictured segments of bowel from eight patients undergoing resection for Crohn's disease, and normal colon from six patients undergoing resection for benign and malignant colorectal disease. Fibroblasts were cultured with transforming growth factor (TGF) beta and corticosteroids. After 24 h the culture supernatant was collected for VEGF assay by enzyme-linked immunosorbent assay.

RESULTS

VEGF production was significantly higher in fibroblasts isolated from strictures (mean(s.e.m.) 1980(260) pg/ml) than from non-strictured segments (1116(165) pg/ml) in patients with Crohn's disease or control fibroblasts (898(93) pg/ml). TGF-beta increased VEGF production in normal and non-strictured Crohn's fibroblasts. Corticosteroids suppressed unstimulated VEGF production in all groups.

CONCLUSION

Enhanced serosal fibroblast VEGF production might play a role in initiating stricture formation in Crohn's disease. VEGF production in serosal fibroblasts is sensitive to stimulation with TGF-beta. Corticosteroids may reduce stricturing through suppression of VEGF.

Vascular permeability factor/vascular endothelial growth factor induces lymphangiogenesis as well as angiogenesis

Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A) is a multifunctional cytokine with important roles in pathological angiogenesis. Using an adenoviral vector engineered to express murine VEGF-A(164), we previously investigated the steps and mechanisms by which this cytokine induced the formation of new blood vessels in adult immunodeficient mice and demonstrated that the newly formed blood vessels closely resembled those found in VEGF-A-expressing tumors. We now report that, in addition to inducing angiogenesis, VEGF-A(164) also induces a strong lymphangiogenic response. This finding was unanticipated because lymphangiogenesis has been thought to be mediated by other members of the VPF/VEGF family, namely, VEGF-C and VEGF-D. The new "giant" lymphatics generated by VEGF-A(164) were structurally and functionally abnormal: greatly enlarged with incompetent valves, sluggish flow, and delayed lymph clearance. They closely resembled the large lymphatics found in lymphangiomas/lymphatic malformations, perhaps implicating VEGF-A in the pathogenesis of these lesions. Whereas the angiogenic response was maintained only as long as VEGF-A was expressed, giant lymphatics, once formed, became VEGF-A independent and persisted indefinitely, long after VEGF-A expression ceased. These findings raise the possibility that similar, abnormal lymphatics develop in other pathologies in which VEGF-A is overexpressed, e.g., malignant tumors and chronic inflammation.

Vascular endothelial growth factor mRNA synthesis by peripheral blood mononuclear cells in patients with acute myocardial infarction

We studied vascular endothelial growth factor (VEGF) mRNA synthesis by peripheral blood mononuclear cells (PBMCs) in 30 patients with acute myocardial infarction (AMI) and 20 healthy individuals. PBMCs were isolated from all patients on days 3 and 14 after the onset of aMI, and from all of control individuals. To prepare samples containing identical amounts of GAPDH cDNA, competitive PCR was performed by co-amplifying serial dilutions of GAPDH mutant templates. Next, to measure VEGF cDNA quantitatively in the samples containing identical amounts of GAPDH, we also used competitive PCR by co-amplifying mutant templates of VEGF. The serum VEGF concentrations on day 14 in patients with aMI were measured by an ELISA method. Higher levels of VEGF mRNA in PBMCs were present on day 14 than either on day 3 or in the control group. Serum VEGF concentrations correlated with the VEGF mRNA levels of PBMCs on day 14. Peak serum CK levels correlated well with VEGF mRNA levels of PBMCs on day 14. The present findings suggest that PBMCs may be one of the candidates responsible for elevated circulatory VEGF protein following aMI. In addition, VEGF mRNA may be overexpressed in PBMCs in response to cardiac muscle damage.

Vascular endothelial growth factor may contribute to increased vascular permeability in acute respiratory distress syndrome

The development of noncardiogenic pulmonary edema is a characteristic feature of acute respiratory distress syndrome (ARDS). We hypothesized that vascular endothelial growth factor (VEGF) would play an important role in this process. Plasma VEGF was measured in 40 patients with ARDS, 28 at-risk patients, 14 normal control subjects, and 9 ventilated control subjects. Cultured peripheral blood mononuclear cells (PBM) supernatant VEGF was measured in 21 patients with ARDS and 12 at-risk patients, respectively. The functional importance of VEGF as a mediator of endothelial permeability was assessed by measuring albumin flux across human pulmonary endothelial cell monolayers. Plasma VEGF was significantly elevated in patients with ARDS compared with at-risk patients, normal control subjects, and ventilated control subjects (p = 0.01, p = 0.0001, and p = 0.002, respectively). PBM from patients with ARDS produced significantly more VEGF in vitro than at-risk patients (p = 0.05). Albumin flux across human pulmonary endothelial cell monolayers was significantly increased following the addition of plasma from patients with ARDS compared with plasma from normal control subjects (p = 0.008). When VEGF activity in plasma was neutralized by the addition of a soluble VEGF inhibitor, the albumin flux induced by ARDS plasma was reduced by 48%. We conclude that VEGF makes a significant contribution to the endothelial cell permeability-inducing activity in plasma from patients with ARDS, and may play an important role in the development of noncardiogenic pulmonary edema in ARDS.

Vascular endothelial growth factor production in polymyalgia rheumatica

OBJECTIVE

To evaluate peripheral production and synovial expression of vascular endothelial growth factor (VEGF) in polymyalgia rheumatica (PMR).

METHODS

Circulating levels of VEGF in PMR (serum concentration and in vitro release by peripheral blood mononuclear cells [PBMC]) were investigated by enzyme-linked immunosorbent assay. Local expression of VEGF in shoulder synovial tissue was investigated by immunohistochemical analysis. Investigations were performed in patients with active, untreated disease and in patients treated with corticosteroids.

RESULTS

VEGF serum concentrations were significantly higher in untreated PMR patients than in normal control subjects. During steroid treatment, VEGF serum concentrations reached their lowest level after the sixth month of treatment. PBMC isolated from untreated PMR patients spontaneously secreted a higher amount of VEGF compared with PBMC from control subjects. Corticosteroid therapy did not affect the ability of PBMC to produce VEGF. Immunohistochemical staining performed on shoulder synovial tissue showed VEGF expression in both the lining layer and the sublining area. In 3 of 4 treated patients, no VEGF staining was found in synovial tissue during corticosteroid therapy. VEGF expression correlated with vessel density, but was not associated with alphavbeta3 and alphavbeta5 integrin expression.

CONCLUSION

Peripheral and local VEGF releases have different responses to steroid treatment in PMR. The lack of response to corticosteroids by peripheral VEGF production supports the hypothesis that systemic involvement is dominant in PMR. At the synovial level, VEGF production is linked to vascular proliferation and is thus directly involved in the pathogenesis of synovitis.

Immunology of inflammatory bowel disease

The immunology of inflammatory bowel disease continues to be an intense area of investigation for clues to the pathogenesis of Crohn disease and ulcerative colitis. As typical with complex diseases, inflammatory bowel disease research is continuously evolving. Without abandoning traditional areas of study, such as humoral and cellular immunity and cytokines, investigation is broadening to explore new molecules and biologic phenomena. Novel cytokines and cell adhesion molecules appear to be involved in inflammation, while the role of nitric oxide is being clarified. Leukocyte resistance to apoptosis appears to be a major contributing factor to Crohn disease. Epithelial cell-derived defensins and receptors are arising as key molecules mediating the interaction of innate and acquired mucosal immunity with the enteric flora, and explaining how the latter participates in gut inflammation. The results of these combined studies are opening novel therapeutic horizons whose implementation offers better forms of treatment.