Role of anti-angiogenic factor endostatin in the pathogenesis of experimental ulcerative colitis

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

An Analysis of the Content of Metalloproteinases in the Intestinal Wall of Patients with Crohn's Disease

One of the inflammatory bowel diseases is Crohn's disease. Although this term has been used in the medical community since 1932, a significant increase in the number of publications occurs at the end of the 20th century and the beginning of the 21st century. Crohn's disease is a disease that cannot be fully cured. In many cases, it is chronic, i.e., recurrent. All preventive and therapeutic measures taken by doctors are aimed at inhibiting the development of the disease and minimizing the occurrence of any potential "side effects" resulting from the developing disease. One of the diagnostic methods is the qualitative and quantitative determination of metalloproteinases in inflammatory tissues and in the blood. The aim of the study was the quantitative and qualitative determination of metalloproteinases in inflammatory bowel tissues in patients diagnosed with Crohn's disease. The in vitro study was performed on surgical tissues from patients diagnosed with Crohn's disease. The results show that in inflammatory tissues the concentration of metalloproteinases -3, -7, -8, -9 was higher compared to tissues taken from the resection margin without signs of inflammation, defined as healthy. The experiment confirmed that the biochemical test, which is the determination of metalloproteinases in tissues, is a useful diagnostic tool to differentiate inflammatory from non-inflammatory tissues.

The Roles of Vascular Endothelial Growth Factor, Angiostatin, and Endostatin in Nasal Polyp Development

Background and Objectives: Microvascular remodeling and angiogenesis are elements of tissue remodeling characteristic of chronic inflammatory diseases, including nasal polyps (NPs). Angiogenesis reflects the balance between the actions of pro- and anti-angiogenic factors. Many pro-angiogenic factors are known, including vascular endothelial growth factor (VEGF). A number of anti-angiogenic factors (e.g., angiostatin and endostatin) also has been identified. Our objective was to assess the roles of VEGF, angiostatin, and endostatin in NP development.Methods: The expression levels of VEGF, angiostatin, and endostatin were measured in NPs harvested during endoscopic endonasal surgery and compared with those in inferior turbinate mucosa (control) samples acquired from patients with hypertrophic rhinitis without allergy. Western blotting and immunohistochemical staining were used to analyze all samples.Results: The levels of VEGF and angiostatin were significantly higher in the NP subjects than in the controls. Neither the VEGF/angiostatin ratio nor the endostatin level differed significantly between the two groups. However, the VEGF/endostatin ratio was significantly higher in the NP than in the control group. Both the NP and control tissues were diffusely immunoreactive for VEGF, angiostatin, and endostatin.Conclusion: NP-associated hypoxia can elevate angiostatin level; moreover, an imbalance in the VEGF/endostatin ratio can contribute to NP formation.

Stem Cell-Based Therapies for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic, relapsing disease that severely affects patients’ quality of life. The exact cause of IBD is uncertain, but current studies suggest that abnormal activation of the immune system, genetic susceptibility, and altered intestinal flora due to mucosal barrier defects may play an essential role in the pathogenesis of IBD. Unfortunately, IBD is currently difficult to be wholly cured. Thus, more treatment options are needed for different patients. Stem cell therapy, mainly including hematopoietic stem cell therapy and mesenchymal stem cell therapy, has shown the potential to improve the clinical disease activity of patients when conventional treatments are not effective. Stem cell therapy, an emerging therapy for IBD, can alleviate mucosal inflammation through mechanisms such as immunomodulation and colonization repair. Clinical studies have confirmed the effectiveness of stem cell transplantation in refractory IBD and the ability to maintain long-term remission in some patients. However, stem cell therapy is still in the research stage, and its safety and long-term efficacy remain to be further evaluated. This article reviews the upcoming stem cell transplantation methods for clinical application and the results of ongoing clinical trials to provide ideas for the clinical use of stem cell transplantation as a potential treatment for IBD.

Host transcriptome and microbiome interaction modulates physiology of full-sibs broilers with divergent feed conversion ratio

Efficient livestock production relies on effective conversion of feed into body weight gain (BWG). High levels of feed conversion are especially important in production of broiler chickens, birds reared for meat, where economic margins are tight. Traits associated with improved broiler growth and feed efficiency have been subjected to intense genetic selection, but measures such as feed conversion ratio (FCR) remain variable, even between full siblings (sibs). Non-genetic factors such as the composition and function of microbial populations within different enteric compartments have been recognized to influence FCR, although the extent of interplay between hosts and their microbiomes is unclear. To examine host–microbiome interactions we investigated variation in the composition and functions of host intestinal-hepatic transcriptomes and the intestinal microbiota of full-sib broilers with divergent FCR. Progeny from 300 broiler families were assessed for divergent FCR set against shared genetic backgrounds and exposure to the same environmental factors. The seven most divergent full-sib pairs were chosen for analysis, exhibiting marked variation in transcription of genes as well as gut microbial diversity. Examination of enteric microbiota in low FCR sibs revealed variation in microbial community structure and function with no difference in feed intake compared to high FCR sibs. Gene transcription in low and high FCR sibs was significantly associated with the abundance of specific microbial taxa. Highly intertwined interactions between host transcriptomes and enteric microbiota are likely to modulate complex traits like FCR and may be amenable to selective modification with relevance to improving intestinal homeostasis and health.

Active Vaccination With EMMPRIN-Derived Multiple Antigenic Peptide (161-MAP) Reduces Angiogenesis in a Dextran Sodium Sulfate (DSS)-Induced Colitis Model

Ulcerative colitis (UC) is an autoimmune disease that affects the colon and shares many clinical and histological features with the dextran sulfate sodium (DSS)-induced colitis model in mice. Angiogenesis is a critical component in many autoimmune diseases, as well as in the DSS-induced colitis model, and is it partially mediated by EMMPRIN, a multifunctional protein that can induce the expression of both the potent pro-angiogenic vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs). We asked whether targeting EMMPRIN by active vaccination, using a novel, specific epitope in the protein, synthesized as a multiple antigenic peptide (MAP), could trigger beneficial effects in the DSS-induced colitic C57BL/6J mice. Mice were vaccinated with four boost injections (50 μg each) of either 161-MAP coding for the EMMPRIN epitope or the scrambled control peptide (Scr-MAP) emulsified in Freund's adjuvant. We show that male mice that were vaccinated with 161-MAP lost less weight, demonstrated improved disease activity indices (DAI), had reduced colitis histological score, and their colons were longer in comparison to mice vaccinated with the Scr-MAP. The 161-MAP vaccination also reduced serum and colon levels of EMMPRIN, colon concentrations of VEGF, MMP-9, and TGFβ, and vessel density assessed by CD31 staining. A similar effect was observed in female mice vaccinated with 161-MAP, including weight loss, colitis histological score, colon length, colon levels of EMMPRIN and colon concentrations of VEGF. However, for female mice, the changes in DAI values, EMMPRIN serum levels, and MMP-9 and TGFβ colon concentrations did not reach significance. We conclude that our strategy of alleviating autoimmunity in this model through targeting angiogenesis by actively vaccinating against EMMPRIN was successful and efficient in reducing angiogenesis.

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.

Effect of Niacin on Inflammation and Angiogenesis in a Murine Model of Ulcerative Colitis

Butyrate and niacin are produced by gut microbiota, however butyrate has received most attention for its effects on colonic health. The present study aimed at exploring the effect of niacin on experimental colitis as well as throwing some light on the ability of niacin to modulate angiogenesis which plays a crucial role of in the pathogenesis of inflammatory bowel disease. Rats were given niacin for 2 weeks. On day 8, colitis was induced by intrarectal administration of iodoacetamide. Rats were sacrificed on day 15 and colonic damage was assessed macroscopically and histologically. Colonic myeloperoxidase (MPO), tumour necrosis factor (TNF)-α, interleukin (IL)-10, vascular endothelial growth factor (VEGF), angiostatin and endostatin levels were determined. Niacin attenuated the severity of colitis as demonstrated by a decrease in weight loss, colonic wet weight and MPO activity. Iodoacetamide-induced rise in the colonic levels of TNF-α, VEGF, angiostatin and endostatin was reversed by niacin. Moreover, niacin normalized IL-10 level in colon. Mepenzolate bromide, a GPR109A receptor blocker, abolished the beneficial effects of niacin on body weight, colon wet weight as well as colonic levels of MPO and VEGF. Therefore, niacin was effective against iodoacetamide-induced colitis through ameliorating pathologic angiogenesis and inflammatory changes in a GPR109A-dependent manner.

Promoting inflammatory lymphangiogenesis by vascular endothelial growth factor-C (VEGF-C) aggravated intestinal inflammation in mice with experimental acute colitis

Angiogenesis and lymphangiogenesis are thought to play a role in the pathogenesis of inflammatory bowel diseases (IBD). However, it is not understood if inflammatory lymphangiogenesis is a pathological consequence or a productive attempt to resolve the inflammation. This study investigated the effect of lymphangiogenesis on intestinal inflammation by overexpressing a lymphangiogenesis factor, vascular endothelial growth factor-C (VEGF-C), in a mouse model of acute colitis. Forty eight-week-old female C57BL/6 mice were treated with recombinant adenovirus overexpressing VEGF-C or with recombinant VEGF-C156S protein. Acute colitis was then established by exposing the mice to 5% dextran sodium sulfate (DSS) for 7 days. Mice were evaluated for disease activity index (DAI), colonic inflammatory changes, colon edema, microvessel density, lymphatic vessel density (LVD), and VEGFR-3mRNA expression in colon tissue. When acute colitis was induced in mice overexpressing VEGF-C, there was a significant increase in colonic epithelial damage, inflammatory edema, microvessel density, and neutrophil infiltration compared to control mice. These mice also exhibited increased lymphatic vessel density (73.0±3.9 vs 38.2±1.9, P<0.001) and lymphatic vessel size (1974.6±104.3 vs 1639.0±91.5, P<0.001) compared to control mice. Additionally, the expression of VEGFR-3 mRNA was significantly upregulated in VEGF-C156S mice compared to DSS-treated mice after induction of colitis (42.0±1.4 vs 3.5±0.4, P<0.001). Stimulation of lymphangiogenesis by VEGF-C during acute colitis promoted inflammatory lymphangiogenesis in the colon and aggravated intestinal inflammation. Inflammatory lymphangiogenesis may have pleiotropic effects at different stages of IBD.

Angiogenesis in Inflammatory Bowel Disease

Angiogenesis is an important component of pathogenesis of inflammatory bowel disease (IBD). Chronic inflammation and angiogenesis are two closely related processes. Chronic intestinal inflammation is dependent on angiogenesis and this angiogenesis is modulated by immune system in IBD. Angiogenesis is a very complex process which includes multiple cell types, growth factors, cytokines, adhesion molecules, and signal transduction. Lymphangiogenesis is a new research area in the pathogenesis of IBD. While angiogenesis supports inflammation via leukocyte migration, carrying oxygen and nutrients, on the other hand, it has a major role in wound healing. Angiogenic molecules look like perfect targets for the treatment of IBD, but they have risk for serious side effects because of their nature.

Matrix metalloproteinases in inflammatory bowel disease: an update. Mediators Inflamm. 2015;2015:964131. [PMID: 25948887 PMCID: PMC4408746 DOI: 10.1155/2015/964131]

Matrix metalloproteinases (MMPs) are known to be upregulated in inflammatory bowel disease (IBD) and other inflammatory conditions, but while their involvement is clear, their role in many settings has yet to be determined. Studies of the involvement of MMPs in IBD since 2006 have revealed an array of immune and stromal cells which release the proteases in response to inflammatory cytokines and growth factors. Through digestion of the extracellular matrix and cleavage of bioactive proteins, a huge diversity of roles have been revealed for the MMPs in IBD, where they have been shown to regulate epithelial barrier function, immune response, angiogenesis, fibrosis, and wound healing. For this reason, MMPs have been recognised as potential biomarkers for disease activity in IBD and inhibition remains a huge area of interest. This review describes new roles of MMPs in the pathophysiology of IBD and suggests future directions for the development of treatment strategies in this condition.

Matrix metalloproteinase-9: its interplay with angiogenic factors in inflammatory bowel diseases. Dis Markers. 2014;2014:643645. [PMID: 24803722 PMCID: PMC3988740 DOI: 10.1155/2014/643645]

Matrix metalloproteinase- (MMP-) 9 is one of the main metalloproteinases reported to be involved in extracellular matrix degradation and recently also in triggering of angiogenic switch in the course of inflammatory bowel diseases (IBD). The goal of our studies was to estimate in one experimental setting the levels of MMP-9 in sera of Crohn's Disease (CD) and ulcerative colitis (UC) patients and to evaluate its possible diagnostic potential in comparison with other biochemical markers and selected proinflammatory and angiogenic factors. The study group included 176 subjects (CD = 64, UC = 85, control = 27). Concentrations of serum MMP-9 were significantly higher in active than inactive forms of IBD, being higher in active UC than in active CD. Both in the case of CD and UC serum MMP-9 positively correlated with disease activity, IL-6 levels, platelet and leukocyte count, midkine, and PDGF-BB, as well as in UC with ESR and in CD with CRP, IL-1, and VEGF-A. Diagnostic accuracy of MMP-9 in distinguishing active UC from active CD was 66%, and displayed higher specificity than CRP (79.0% versus 61.6%, resp.). Evaluation of serum MMP-9 concentrations could aid in differentiation of active UC from active CD. MMP-9 correlated better with inflammatory and angiogenic parameters in CD than in UC.

Protective effects of hydrogen-rich saline on ulcerative colitis rat model

BACKGROUND

Ulcerative colitis (UC) is associated with enhanced production of reactive oxygen species and altered angiogenesis. Molecular hydrogen has been documented as a novel antioxidant to treat various reactive oxygen species-related diseases. The present study aimed to investigate the effects of hydrogen on UC using a rat model.

MATERIALS AND METHODS

UC in rats was induced with intracolonically administrated acetic acid. Hydrogen was supplied through intraperitoneal injection of 10 or 20 mL/kg hydrogen-rich saline. The hydrogen treatment was performed once every 2 d and lasted 2 wk. The stool consistency and weight loss were used to evaluate UC development. Colonic mucosal damage at the end of the experiment was scored using the macroscopic and microscopic observations. Vascular endothelial growth factor expression in the colonic mucosa was determined using immunohistochemistry.

RESULTS

The administration of acetic acid induced acute rat UC, as indicated by diarrhea, weight loss, and colonic mucosal damage. Treatment with hydrogen-rich saline reduced the weight loss and diarrhea and alleviated the colonic mucosal damage in the UC rats. In addition, the expression of vascular endothelial growth factor in the UC rats increased and could be inhibited by hydrogen treatment.

CONCLUSIONS

Antioxidative hydrogen-rich saline effectively protected the rats from UC, which might be, at least in part, because of inhibition of vascular endothelial growth factor.

Therapeutic DNA vaccination and RNA interference in inflammatory bowel disease

Angiogenesis plays a significant role in numerous diseases. Recently, dysbalanced angiogenesis was found to be a component of pathogenesis of inflammatory bowel disease (IBD). Therefore, inhibition of angiogenesis is a novel therapeutic strategy that alleviates the inflammation and clinical outcomes of IBD. Bacteria act as vectors for the delivery of therapeutic sequences, a process that is particularly suitable in IBD, due to the natural occurrence of bacteria in gut. The main focus of the present study was the application of bacterial gene therapy in the modulation of angiogenesis in IBD. As a target molecule we used the main proangiogenic factor, vascular endothelial growth factor (VEGF). Bacterial strain Salmonella typhimurium SL7207 was used as a gene delivery vector for oral application. DNA vaccination and RNA interference were examined and their efficiency in improving the course of the disease in dextran sulfate sodium-induced colitis in mice was compared. The two approaches yielded similar beneficial results in evaluation of the disease activity parameters (stool consistency, weight loss and colon length) as well as VEGF expression and tumor necrosis factor-α (TNF-α). Improvement in all of the parameters compared with the control groups not treated by therapeutic bacterial strains was also observed. All the bacterial groups showed similar improvement in histopathological scoring. Results of this study are consistent with the literature and provide a basis for additional studies on the modulation of angiogenesis in IBD.

Endostatin, an angiogenesis inhibitor, ameliorates bleomycin-induced pulmonary fibrosis in rats

Background

Recent evidence has demonstrated the role of angiogenesis in the pathogenesis of pulmonary fibrosis. Endostatin, a proteolytic fragment of collagen XVIII, is a potent inhibitor of angiogenesis. The aim of our study was to assess whether endostatin has beneficial effects on bleomycin (BLM)-induced pulmonary fibrosis in rats.

Methods

The rats were randomly divided into five experimental groups: (A) saline only, (B) BLM only, (C) BLM plus early endostatin treatment, (D) BLM plus late endostatin treatment, and (F) BLM plus whole-course endostatin treatment. We investigated the microvascular density (MVD), inflammatory response and alveolar epithelial cell apoptosis in rat lungs in each group at different phases of disease development.

Results

Early endostatin administration attenuated fibrotic changes in BLM-induced pulmonary fibrosis in rats. Endostatin treatment decreased MVD by inhibiting the expression of VEGF/VEGFR-2 (Flk-1) and the activation of extracellular signal-regulated protein kinase 1/2 (ERK1/2). Endostatin treatment also decreased the number of inflammatory cells infiltrating the bronchoalveolar lavage fluid during the early inflammatory phase of BLM-induced pulmonary fibrosis. In addition, the levels of tumour necrosis factor-α (TNF-α) and transforming growth factor β1 (TGF-β1) were reduced by endostatin treatment. Furthermore, endostatin decreased alveolar type II cell apoptosis and had an epithelium-protective effect. These might be the mechanism underlying the preventive effect of endostatin on pulmonary fibrosis.

Conclusions

Our findings suggest that endostatin treatment inhibits the increased MVD, inflammation and alveolar epithelial cell apoptosis, consequently ameliorating BLM-induced pulmonary fibrosis in rats.

Effect of treatment with safflower solution on expression of VEGF and bFGF in ulcerative colitis in rats

AIM: To evaluate the therapeutic effect of safflower solution on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced ulcerative colitis in rats and to explore the underlying mechanisms by observing the expression of vascular endothelial growth factor (VEGF) and basal fibroblast growth factor (bFGF).

METHODS: Thirty Wistar rats were randomly divided into normal control group, model group and safflower group. Ulcerative colitis was induced in the safflower group and model group with TNBS by enema. Rats of the safflower group were intraperitoneally injected with safflower solution. After ten days, all rats were killed. Disease activity index (DAI), colon macroscopic damage score (CMDS) and histological damage score were evaluated. Pathological changes in the colonic mucosa were examined by HE staining. The expression of VEGF and bFGF in the colonic mucosa was detected by real time-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC).

RESULTS: Compared to normal controls, the DAI, CMDS and histological damage scores in model rats were significantly increased (all P < 0.01). Compared to the model group, the above parameters were significantly improved in the safflower group (all P < 0.05). Compared to normal controls, the expression levels of VEGF and bFGF in model rats were increased significantly (all P < 0.01). Treatment with safflower solution significantly decreased the expression levels of VEGF mRNA and protein in ulcerative colitis (both P < 0.05).

CONCLUSION: Treatment with safflower solution could reduce inflammatory injury in a rat model of ulcerative colitis possibly by reducing the expression of VEGF and inhibiting pathologic angiogenesis in the colonic mucosa.

Antiangiogenic and anticancer molecules in cartilage

Cartilage is one of the very few naturally occurring avascular tissues where lack of angiogenesis is the guiding principle for its structure and function. This has attracted investigators who have sought to understand the biochemical basis for its avascular nature, hypothesising that it could be used in designing therapies for treating cancer and related malignancies in humans through antiangiogenic applications. Cartilage encompasses primarily a specialised extracellular matrix synthesised by chondrocytes that is both complex and unique as a result of the myriad molecules of which it is composed. Of these components, a few such as thrombospondin-1, chondromodulin-1, the type XVIII-derived endostatin, SPARC (secreted protein acidic and rich in cysteine) and the type II collagen-derived N-terminal propeptide (PIIBNP) have demonstrated antiangiogenic or antitumour properties in vitro and in vivo preclinical trials that involve several complicated mechanisms that are not completely understood. Thrombospondin-1, endostatin and the shark-cartilage-derived Neovastat preparation have also been investigated in human clinical trials to treat several different kinds of cancers, where, despite the tremendous success seen in preclinical trials, these molecules are yet to show success as anticancer agents. This review summarises the current state-of-the-art antiangiogenic characterisation of these molecules, highlights their most promising aspects and evaluates the future of these molecules in antiangiogenic applications.

Pretreatment with anti-VEGF therapy may exacerbate inflammation in experimental acute colitis

AIM

Our previous investigations of angiogenesis in inflammatory bowel disease showed that vascular endothelial growth factor (VEGF) blockade reduced colonic neovascularization and inflammation. We hypothesized that pretreatment with bevacizumab, a monoclonal anti-VEGF antibody, would attenuate the severity of angiogenesis and inflammation in a murine model of colitis.

METHODS

C57BL/6 mice were treated with intraperitoneal injections of bevacizumab (250 μg/dose) before induction of colitis with dextran sulfate sodium (DSS). The colons were examined at predetermined time points. Colonic inflammation and microvessel density were assessed microscopically.

RESULTS

All mice acutely developed melena and weight loss (18.8% ± 1.1% control vs 20.2% ± 1.1% treated, P = .37) and regained a similar weight percentage after the recovery (26.5% ± 4.0% vs 20.9% ± 4.4%, P = .37). Microvessel density acutely increased in both groups in response to DSS, with a trend toward inhibited angiogenesis in the treated group at the conclusion of the acute phase (194,100 ± 14,240 vs 149,400 ± 17,590 μm(2), P = .11). Bevacizumab-treated mice exhibited significantly increased inflammation after the acute phase (8.3 ± 0.8 vs 13.0 ± 2.0, P = .05), but were similar to control after the recovery (7.3 ± 1.5 vs 5.5 ± 1.0, P = .27).

CONCLUSIONS

Preemptive VEGF inhibition does not significantly attenuate angiogenesis and, in fact, worsens inflammation in a model of acute colitis. Preventive VEGF blockade may disrupt healing and exacerbate injury via alternative angiogenic or inflammatory pathways.