Increased expression of vascular endothelial growth factor and capillary density in hearts of spontaneously hypertensive rats

OBJECTIVE: The role of VEGF in vascular remodeling of target organs exposed to chronic hypertension is poorly understood. The authors compared capillary density (CD), capillary-to-fiber ratio (C/F), and VEGF mRNA expression in the hearts (left ventricle [LV]), and skeletal muscles (soleus and anterior tibialis [AT]) of 18-week-old male spontaneously hypertensive rats (SHR) and age-matched male Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats. METHODS: CD or C/F in LV, soleus, and AT of SHR, WKY, and SD rats was determined by analysis of randomly acquired digital images of cryosections stained with FITC-conjugated GS-I lectin. VEGF mRNA expressions in the tissues were determined by Northern blot. RESULTS: VEGF mRNA expressions in LV of SHR were 3.84- and 5.05-fold higher, compared to SD and WKY rats, respectively (n = 6; p < .01). There were no significant differences in VEGF mRNA expression in soleus or AT among SHR, WKY, and SD rats (p > .05). CD in LV of SHR (4975 +/- 167) was significantly higher than WKY or SD rats, 4151 +/- 169 and 3807 +/- 187 mm(-2), respectively (p < .05). In LV of SHR, C/F increased (35%) more significantly than CD (increased 20%), compared to WKY rats. CD, or C/F in soleus or AT of SHR was similar to that observed in WKY or 8D rats. CONCLUSIONS: VEGF expression, CD, and C/F in the heart (LV) of SHR are significantly increased, compared to WKY and SD rats. The data are consistent with the possibility that VEGF may contribute to capillary growth as a compensatory response to hypertension.     

Increased expression of vascular endothelial growth factor in bone marrow of multiple myeloma patients

Background: Angiogenesis (neovascularization) is a multistep process in which new blood vessels grow from existing vessels. Angiogenesis is associated with the growth, dissemination, and metastasis of solid tumors. There is increasing evidence that neovascularization may be important in hematological malignancies. Several studies suggest that vascular endothelial growth factor (VEGF) is one of the most important cytokines responsible for the development, maintenance, and progression of multiple myeloma (MM) by promoting bone marrow angiogenesis. A high serum concentration of VEGF has been reported in MM patients. The aim of this study was to evaluate the expression of VEGF in the bone marrow of MM patients. Methods: Eighteen paraffin-embedded bone marrow core biopsy specimens from newly diagnosed patients with MM were evaluated. In addition, 10 bone marrow core biopsy specimens from adult patients without evidence of malignancy were used as controls. Bone marrow sections were stained immunohistochemically for VEGF. Results: Our data show that multiple myeloma is associated with an increased expression of VEGF in the bone marrow. Conclusions: Our observation supports previous studies suggesting that angiogenesis may play a role in the pathophysiology of hematopoietic malignancies. The clinical significance of this phenomenon needs further investigation. However, this study provides rationale for the use of angiogenesis inhibitors in MM therapy.     

Increased vascular endothelial growth factor in acute eosinophilic pneumonia.

Acute eosinophilic pneumonia (AEP) is associated with the presence of diffuse pulmonary infiltrates on the chest radiograph and an increased number of eosinophils and an elevation of interleukin (IL)-5 levels in bronchoalveolar lavage (BAL) fluid. Vascular endothelial growth factor (VEGF) is a constitutively expressed protein encoded by messenger ribonucleic acid in human eosinophils and is released following stimulation with IL-5. However, the roles of IL-5 and VEGF in the pathogenesis or activity of this disease have not been clarified. The authors investigated the cells and the levels of these two factors in BAL fluid in five AEP patients and five normal controls before and after corticosteroid treatment. The absolute number of eosinophils-mL(-1), IL-5 and VEGF levels in patients before treatment were higher than in controls (53.8 versus 0.3 x 10(4) x mL(-1), 490.1 versus 5.2 pg x mL(-1) and 643.0 versus 133.9 pg x mL(-1), respectively). IL-5 and VEGF rapidly decreased to the control level in parallel with clinical improvement. The relationship between eosinophilia and IL-5 and VEGF levels was strongly significant. Elevated interleukin-5 in the lung may initiate the recruitment of eosinophils and enhance the release of mediators, such as vascular endothelial growth factor from eosinophils, which, in turn, increases the permeability of blood vessels.     

Increased serum vascular endothelial growth factor level in Churg-Strauss syndrome

BACKGROUND: Churg-Strauss syndrome (CSS) is a rare form of systemic vasculitis occurring in patients with asthma and hypereosinophilia. For optimal treatment, prompt distinction of CSS from asthma is necessary; however, there are few serologic screening markers for this purpose. Vascular endothelial growth factor (VEGF), a vascular permeability factor, has been associated with other systemic vasculitis such as Wegener granulomatosis and giant-cell arteritis. OBJECTIVE: The aim of this study was to clarify the clinical value of the measurement of serum VEGF for the distinction of CSS from asthma. METHODS: We investigated serum VEGF levels in 18 CSS patients, 19 asthma patients, and 12 acute bronchitis patients. We also performed immunohistochemical analysis for VEGF. RESULTS: The serum VEGF levels of CSS patients were significantly higher than those of asthma patients and acute bronchitis patients. The sensitivity and specificity to distinguish CSS from asthma were 93.3% and 81.8%, respectively (cutoff, 600 pg/mL). Infiltrating eosinophils stained intensely positive for VEGF, and serum VEGF levels showed a significant correlation with peripheral eosinophil counts. Serum VEGF levels decreased significantly after therapy (p < 0.001). The infiltrating eosinophils in the CSS lesion stained positive for VEGF in the immunohistochemical analysis. CONCLUSION: VEGF is one of the useful screening markers for the distinction of CSS from asthma. We suggest that VEGF might be associated with the pathogenesis of CSS.     

Insulin stimulates the growth and tube formation of human microvascular endothelial cells through autocrine vascular endothelial growth factor.

Insulin treatment is known epidemiologically as an independent risk factor for the progression of diabetic retinopathy. However, how insulin exacerbates the retinopathy is not yet fully understood. In this study, we investigate the effects of insulin on the growth and tube formation of microvascular endothelial cells (EC). When human skin microvascular EC were grown under various concentrations of insulin, DNA synthesis as well as tube formation of EC was found to be significantly stimulated. We obtained evidence that it is mainly vascular endothelial growth factor (VEGF) that mediates the angiogenic activity of insulin as follows. (1) Insulin upregulates the level of mRNA coding for secretory forms of VEGF, while the expression of the two VEGF receptor genes, kinase insert domain-containing receptor (kdr) and fms-like tyrosine kinase1 (flt1), was essentially unchanged by exposure to insulin. (2) A monoclonal antibody against human VEGF can completely neutralize both the proliferation and the tube formation of EC induced by insulin. The angiogenic effects of insulin were additive with those of hypoxia, a principal factor that causes angiogenesis. Further, insulin significantly stimulated plasminogen activator inhibitor-1 activity in EC. The results thus suggest that insulin not only elicits angiogenesis through the induction of autocrine VEGF but also is a predisposing factor for thrombogenesis, which may give rise to focal ischemia that could superdrive angiogenesis, thereby leading to the exacerbation of diabetic retinopathy.     

肝癌组织血管内皮生长因子表达水平的免疫组化研究

目的　旨在研究血管内皮生长因子 (VEGF)与肝癌微血管形成、生长和转移诸方面的关系。方法　对临床 3 6例肝癌术后癌组织 ,以免疫组织化学法研究VEGF在肿瘤组织的胞内分布及其表达 ;并以ELISA法测定癌灶、癌旁及远癌组织中的VEGF蛋白的表达水平。结果　癌组织中VEGF阳性表达率为 63 .9% ;无包膜或包膜不完整组VEGF阳性表达率与有包膜组存在显著差异 ;肝癌伴有远处转移组VEGF阳性表达水平显著高于无转移组 (P <0 .0 1) ,癌灶组织中VEGF的表达水平明显高于癌旁、远癌组织(P <0 .0 1)。结论资料提示VEGF在肝癌组织中高度表达 ,它在HCC的血管形成、肿瘤发展和转移过程中起重要作用 ,提示癌组织中VEGF过度表达是反映肿瘤侵袭生长及转移潜能的有效指标     

人肝癌组织血管内皮生长因子及微血管密度分析的临床价值

目的 探讨血管内皮生长因子(VEGF)在肝癌(HCC)微血管形成、生长和转移方面的作用。 方法 以免疫组织化学法分析36例HCC组织中VEGF表达状态和细胞内分布,采用微血管染色方法测定微血管密度(MVD),并定量检测癌及癌周组织中总RNA和VEGF水平。 结果 所有HCC组织中VEGF阳性率为63.9％,无包膜组为78.3％,伴有远处转移组为90.9％;VEGF表达与MVD密切相关(t=4.49,,P<0.01);HCC组织VEGF水平或MVD值,在肿瘤直径大小组及肿瘤分化程度高低组间差异无显著性;HCC组织总RNA水平低于癌旁及远癌组织,而VEGF水平明显高于癌旁和远癌组织(q=6.10,P<0.01)。 结论VEGF过度表达和MVD异常是反映HCC侵润生长及转移的有效指标。     

17Beta-estradiol up-regulates vascular endothelial growth factor receptor-2 expression in human myometrial microvascular endothelial cells: role of estrogen receptor-alpha and -beta

Estrogen has a cardiovascular protective role in women due in part to its effect on the vasculature. The roles of the two estrogen receptors (ERs), ERalpha and ERbeta, in the vascular actions of estrogen are unclear, as are effects of estrogen on microvascular endothelial cells (MEC) derived from sex steroid-responsive tissues. The present study demonstrates that 17beta-estradiol, but not progesterone, increases vascular endothelial growth factor (VEGF) receptor (VEGFR) expression on human myometrial MEC measured using biotin-recombinant human (rh) VEGF(165) and flow cytometry. This response occurred in a time- and dose-dependent manner, with significantly increased rhVEGF(165) binding at 3 h and maximal responses between 0.1 and 10 nmol/liter 17beta-estradiol, which was blocked by the antiestrogen ICI 182,780. Approximately 60% of samples demonstrated this response to 17beta-estradiol. All samples of myometrial MEC expressed both ERbeta mRNA and protein demonstrated by semiquantitative RT-PCR and Western blotting. However, ERalpha mRNA and protein were expressed in only 13 of 21 MEC samples. There was a significant association between ERalpha expression in myometrial MEC and their ability to respond to 17beta-estradiol by increasing rhVEGF(165) binding. 17beta-estradiol increased VEGFR-2 expression in ERalpha-expressing MEC isolates, which also demonstrated increased rhVEGF(165) binding, but failed to have these effects on ERalpha negative samples. Similarly, 17beta-estradiol augmented VEGF-induced MEC proliferation in ERalpha-expressing MEC samples, which was blocked by ICI 182,780. These observations suggest that 17beta-estradiol increases VEGFR-2 expression on human myometrial MEC promoting endothelial cell proliferation, an effect that varies between subjects and appears to be mediated primarily by ERalpha.     

Increased blood vascular endothelial growth factor levels in patients with acute myocardial infarction

Vascular endothelial growth factor (VEGF) is a growth factor for vascular endothelial cells in vitro. The present study was designed to determine whether serum VEGF levels increase in patients with acute myocardial infarction (AMI) compared with patients with stable exertional angina and control subjects, and to examine the serial changes of serum VEGF levels in patients with AMI. We examined serum VEGF levels by using antibody prepared from serum immunized with human VEGF(121). The serum VEGF level (pg/ml) was higher (p < 0. 0001) on admission in the patients with AMI (177 +/- 19) than in those with stable exertional angina (61 +/- 7) and control subjects (62 +/- 6). The serum VEGF level (pg/ml) of the patients with AMI was 177 +/- 19 on admission, 125 +/- 9 on day 3, 137 +/- 11 on day 5, 242 +/- 18 at 1 week, and 258 +/- 22 at 2 weeks after admission. The value was higher on admission than on day 3 after admission (p = 0.014), the values were higher at 1 week and 2 weeks than on admission, on day 3, and 5 (p < 0.01). Furthermore, there were correlations between peak VEGF levels at 1 week or 2 weeks after admission and peak creatine kinase levels. The increase of VEGF on admission in the patients with AMI may be due to the hypoxia of acute myocardial ischemia. The elevation at 1 week and 2 weeks from the onset may cause the development of collateral circulation in relation to the healing of the infarction site.     

Increased expression of endothelial antigen PAL-E in human diabetic retinopathy correlates with microvascular leakage

Aims/hypothesis. The Pathologische Anatomie Leiden-Endothelium (PAL-E) antigen is a marker for loss of the blood-brain barrier function in brain tumours. It is endothelium specific and is associated with the endothelial plasmalemmal vesicles (caveolae) involved in transcellular transport. To test whether blood-retinal barrier loss in diabetic retinopathy is associated with cellular changes in the endothelium, the expression of antigen PAL-E in relation to microvascular leakage in human diabetic retinopathy was investigated. Methods. Immunohistochemical staining of frozen tissue sections of postmortem eyes obtained from 30 persons without and 41 persons with diabetes mellitus was carried out with monoclonal antibodies against PAL-E and CD31 and with antibodies against endogenous fibrinogen, albumin and IgG as indicators of vascular leakage. Results. Patchy or uniform microvascular PAL-E staining was observed in the retina of 17 of the 41 eyes of diabetic patients and in 2 of the 30 normal control eyes. In the diabetic eyes, PAL-E staining co-localized with microvascular staining for endogenous fibrinogen, albumin and IgG. Strong staining for PAL-E was observed in sites without blood-tissue barriers, like the choroid. Conclusions/interpretation. In microvessels with an intact blood-retina barrier the endothelial antigen PAL-E is absent. Its expression is increased in retinal vessels of patients with diabetic retinopathy and correlates with microvascular leakage of plasma proteins. This phenotypic shift involving an antigen associated with caveolae suggests that dysfunction of the endothelium forms the cellular basis for microvascular leakage in diabetic retinopathy, rather than passive endothelial damage. [Diabetologia (1999) 42: 596–602] Received: 10 September 1998 and in final revised form: 26 November 1998     

Xanthine oxidase interaction with vascular endothelial growth factor in human endothelial cell angiogenesis

OBJECTIVES: Reduced capillary density occurs early in cardiovascular diseases. Oxidant stress is implicated in endothelial apoptosis. We investigated the effects of xanthine oxidase (XO) on endothelial survival signaling: protein kinase B/Akt, its cross-talk with p38 MAPK and apoptosis pathways, and its effect on vascular tube formation in vascular endothelial growth factor (VEGF)-simulated human umbilical vein cells. METHODS: We studied primary cultured human endothelial cells from the umbilical cord. Reactive oxygen species (ROS) production was detected by dihydroethidium staining, cell-signaling pathways by western blots, cell survival by western blots, and nuclear chromatin and angiogenesis response by MTT proliferation assay and three-dimensional Matrigel cultures. RESULTS: Exogenous XO increased cellular ROS production and caused superoxide-dependent inhibition of Akt phosphorylation and enhancement of p38 MAPK phosphorylation in a time-and dose-dependent manner. In contrast, application of the XO inhibitor oxypurinol or allopurinol inhibited VEGF-stimulated Akt phosphorylation, indicating that endogenous XO promotes VEGF-induced endothelial cell (EC) survival signaling. Exogenous XO induced activation of caspase-3 and reduced expression of the anti-apoptosis protein Bcl-2. Exogenous XO also reduced EC viability, proliferation, and vascular tube formation by p38 MAPK-dependent, phosphoinositide 3-kinase (PI3-K) reversible mechanisms; whereas VEGF promoted EC survival by PI3-K-dependent, p38 MAPK-independent effects. CONCLUSIONS: Exogenous XO activity is an important contributor to endothelial mechanisms for microvascular rarefaction, by modulation of cell survival signaling pathways; however, endogenous XO is necessary for maintaining EC survival.