Infantile hemangioma is a proliferation of beta 4-negative endothelial cells adjacent to HLA-DR-positive cells with dendritic cell morphology

Although hemangioma is referred as to the most common tumor in infancy, the underlying pathogenetic events and the biologic origin of this benign vascular neoplasm have remained obscure. By using immunohistochemistry on frozen sections of infantile hemangiomas, we show here that proliferating endothelial cells abundantly expressed alpha(v)beta(3) but lacked beta(4) integrins. Instead, regressing and involuting infantile hemangiomas due to treatment with IFN-alpha showed positive staining of beta(4) integrin, which might point to the angiogenic significance of beta(4) integrin in infantile hemangiomas. Moreover, immunofluorescence analysis revealed the existence of HLA-DR(+), mostly CD68(+) and partly DC-SIGN/CD209(+) cells with dendritic cell morphology in the intimate vicinity of hemangiomatous vessels. Such cells were also detected in the dermal microvascular unit in normal skin. The coupled occurrence of vascular structures and perivascular cells that were stained positive with markers of monocyte or macrophage or dendritic cells might suggest that the development of infantile hemangioma is a result of vasculogenesis, that is, the formation of primitive blood vessels from angioblasts, rather than of angiogenesis, that is, the sprouting of capillaries from preexisting vessels.     

Neutrophil and endothelial cell activation in the vasa vasorum in vasculo-Behçet disease

AIM: The aim of this study was to analyse the immunopathological mechanisms of vasculo-Beh?et disease, which were also compared to cases of Takayasu's arteritis and inflammatory aneurysm to evaluate differences in inflammatory mechanisms. METHOD AND RESULTS: We reviewed six cases of vasculo-Beh?et disease, four of Takayasu's arteritis and seven inflammatory aneurysms which underwent surgical repair. Immunohistochemical studies were performed on paraffin-embedded tissue using a labelled streptavidin-biotin method, as was in-situ hybridization for Epstein-Barr virus. Microscopically, neutrophils and lymphocytes accumulated around the vasa vasorum. Neutrophils were prominent as compared to Takayasu's arteritis and inflammatory aneurysm. Elastic fibres were not severely destroyed. Endothelial cells (ECs) of most vasa vasorum expressed HLA-DR. The number of vasa vasorum around which inflammatory infiltrating cells were observed in vasculo-Beh?et disease was significantly greater than in inflammatory aneurysms and Takayasu's arteritis (P < 0.001). The cytokines IL-1alpha, TNF-beta and IFN-gamma were expressed in neutrophils and lymphocytes which were distributed around vasa vasorum, as well as neutrophils adherent to HLA-DR positive ECs. CONCLUSION: Our results suggest that vasculo-Beh?et disease should be classified as a neutrophilic vasculitis targeting the vasa vasorum. Aneurysm formation may be related to degeneration of arterial wall caused by inflammation of the vasa vasorum.     

Divergent regulation of vascular endothelial growth factor and of erythropoietin gene expression in vivo

There is accumulating evidence from in vitro experiments that the gene expression of the vascular endothelial growth factor (VEGF) is, like that of the erythropoietin (EPO) gene, regulated by the oxygen tension and by divalent cations such as cobalt. Since the information about the regulation of VEGF gene expression in vivo is rather scarce, this study aimed to examine the influence of hypoxia and of cobalt on VEGF gene expression in different rat organs and to compare it with that on EPO gene expression. To this end male Sprague-Dawley rats were exposed to carbon monoxide (0.1% CO), hypoxia (8% O₂ ) or to cobalt chloride (12 and 60 mg/kg s.c.) for 6 h. mRNA levels for VEGF- 188, -164, and -120 amino acid isoforms in lungs, hearts, kidneys and livers were semiquantitated by RNase protection. For these organs we found a rank order of VEGF mRNA abundance of lung >> heart > kidney = liver. EPO mRNA levels were semiquantitated in kidneys and livers. Hypoxia, CO and cobalt increased EPO mRNA levels 60-fold, 140-fold and 5-fold, respectively, in the kidneys, and 11-fold, 11-fold and 3-fold, respectively, in the livers. None of these manoeuvres caused significant changes of VEGF mRNA in lung, heart or kidneys. Only in the livers did hypoxia lead to a significant (50%) increase of VEGF mRNA. These findings suggest that, in contrast to the in vitro situation, the expression of the VEGF gene in normal rat tissues is rather insensitive to hypoxia. In consequence, the in vivo regulation of the VEGF and the EPO genes appear to differ substantially, suggesting that the regulation of the VEGF and EPO genes may not follow the same essential mechanisms in vivo. Received: 31 July 1995/Received after revision: 20 November 1995/Accepted: 27 November 1995     

Changes in cerebral endothelial barrier antigen, without alteration of permeability for intravenously injected leptin in diet-induced obesity in rats

Leptin, a potent anorectic, 16-kDa, adipose tissue-derived protein, predominantly acts in hypothalamic nuclei, signaling obesity and modulating ingestive behavior. To reach this brain area, leptin, probably has to cross the blood-brain barrier (BBB). In some cases of obesity, enhanced leptin levels in the blood do not result in anorectic effects, probably due to an altered leptin transport across the BBB. Therefore, we investigated the BBB in lean and diet-induced obese Lewis rats. To obtain information about the presence of microvessels with barrier dysfunction we examined three brain areas (hypothalamus, cortex, hippocampus) using a monoclonal antibody which detects intact microvessels of the BBB (anti-endothelial barrier antigen, anti-EBA). The results showed a significantly reduced EBA staining in the brain sections of the obese animals, except the hippocampus, compared to the control group. In a second step we injected I125-labeled leptin intravenously (i.v.) in permanent i.v.-cannulated, unrestrained Lewis rats (lean and obese). We measured the radioactivity in the cerebrospinal fluid after puncture of the cisterna magna, in the blood and brain tissue 90 min after injection. The leptin content in the cerebrospinal fluid and brain was not reduced in obese compared to lean rats, thus showing a similar transport capacity of the BBB in both experimental groups. Therefore, the results of the in vivo investigations do not indicate an impairment of the BBB in diet-induced obesity, despite the immunohistological findings. Further functional and morphological studies are necessary to evaluate the specific role of other organs and distinct forms of leptin (free and protein-bound) in the pathogenesis of diet-induced obesity.     

The relationship of VEGF and PGE2 expression to extracellular matrix remodelling of the tenosynovium in the carpal tunnel syndrome

Tenosynovial thickening within the confined space of the carpal tunnel is thought to be the cause of the carpal tunnel syndrome (CTS). However, little is known about the pathological mechanism of tenosynovial thickening. In this study, the role of prostaglandin E(2) (PGE(2)) and vascular endothelial growth factor (VEGF) (two representative molecules that can induce oedema by increasing vascular permeability) was analysed in CTS by using immunohistochemistry and enzyme-linked immunosorptive assay (ELISA). Expression of these molecules was compared with the patients' clinical histories and a temporary increase in production of these molecules was found in cells within the vessels and synovial lining during the intermediate phase of the syndrome when the histology of the tenosynovium changes from oedematous to fibrotic. Statistical analysis clearly demonstrated that there is a close correlation between the expression of PGE(2) and VEGF. Furthermore, immunohistochemical analysis with anti-proliferating cell nuclear antigen (PCNA) revealed that the area with distinct VEGF expression closely matched the area where endothelial cells, vascular smooth muscle cells, and synovial lining cells proliferate. In contrast, despite marked alteration in the extracellular matrix (ECM) component of the tenosynovium, the fibroblasts responsible for most ECM framework production do not proliferate during any phase of CTS. Histological analysis demonstrated that angiogenesis takes place only during the intermediate phase. Since clusters of capillaries and arterioles are often surrounded by type III collagen-rich, disorganized, degenerate connective tissue, which contains fewer fibroblasts than normal, angiogenesis appears to take place as a part of a regenerative reaction that results in fibrosis. These findings strongly indicate that both PGE(2) and VEGF are expressed in the tenosynovium in CTS during the intermediate phase and induce the histological changes seen in the tenosynovium.     

Isolated unilateral absence of a pulmonary artery: influence of systemic circulation on alveolar capillary vessels

We report a case of isolated unilateral absence of a pulmonary artery. The first clinical symptom that was manifested in the patient was recurrent hemoptysis, and subsequent angiography revealed that the main pulmonary artery was absent in the right lung, which was being fed only from the systemic circulation. Right pneumonectomy was performed, and neither the main pulmonary artery nor its remnant was detected in the resected right lung. Histologically, there were many muscular vessels in the resected lung, with intimal proliferation, or with plexiform-like lesions. The alveolar septum was moderately thickened and alveolar capillary vessels were dilated. We examined the alveolar capillary endothelial cells of the resected lung for immunoreactivity to thrombomodulin (TM) and von Willebrand factor (vWF). The endothelial cells were negative for TM and positive for vWF, while in the normal lung control group, these cells were positive for TM and negative for vWF. We considered that the hemodynamics of the systemic circulation in the resected lung caused the alteration of immunohistochemical characteristics in alveolar capillary endothelial cells.     

High endothelial-like venules in chronically inflamed periodontal tissues exchange polymorphs

A survey of 58 gingival biopsies revealed the presence of periodontal high endothelial-like venules (PHELVs) in chronically inflamed gingival tissues. PHELVs were found to exchange polymorphonuclear cells (PMNs) almost exclusively in advanced periodontitis, with PMNs greatly exceeding the number of mononuclear cells found in PHELVs (P less than 0.001). Electron microscopy confirmed the emigration of PMNs from these vessels. The enzyme histochemical and ultrastructural features as well as the 35SO4 uptake properties of PHELVs were similar to those of the well-characterized high endothelial venules (HEVs) of rat lymph nodes. It is generally accepted that HEVs in lymphoid tissues and inflammatory sites are specially adapted to assist in the emigration of lymphocytes. However, the observation of preferential PMN emigration in the apparent absence of lymphocyte exchange from PHELVs compels further investigation of other possible functions for HEVs. In relation to this, endothelial cells are capable of producing potent cytokines and inflammatory mediators which may contribute to the development of lesions, and the possibility is discussed that high endothelial cells are functionally adapted to enhance the production of such factors.     

Activation of the endothelium by IL-1 alpha and glucocorticoids results in major increase of complement C3 and factor B production and generation of C3a.

Constitutive secretion of complement C3 and factor B by the endothelial cell (EC) is lowered by therapeutic concentrations of glucocorticoids such as hydrocortisone or dexamethasone, whereas regulatory protein factor H production is increased by these hormones. In contrast, the proinflammatory cytokine IL-1 alpha has a stimulatory effect on C3 and factor B secretion by the endothelium and an inhibitory effect on factor H secretion. In this study, we examined the combined effect of IL-1 alpha and glucocorticoids on C3 and factor B expression by the endothelial cell. When dexamethasone or hydrocortisone were added to IL-1 alpha, significant potentialization of IL-1 alpha-induced stimulation of C3 and factor B production was observed, occurring at various concentrations of either stimuli. Dose-response experiments indicate that, in vitro, optimal concentrations are in the range of 10(-7) to 10(-5) M for dexamethasone and 50-200 U for IL-1 alpha. In contrast, dexamethasone counteracts, in an additive way, the inhibitory effect of IL-1 alpha on regulatory complement protein factor H production by EC. Such a potentialization between glucocorticoids and IL-1 alpha was not observed for another marker of endothelial activation, IL-1 alpha-induced stimulation of coagulation tissue factor expression. The association of glucocorticoids and IL-1 alpha therefore appears to be a specific and major stimulus for the secretion of complement C3 and factor B, two acute-phase proteins, by the endothelium. As a result of the in vitro endothelium stimulation by glucocorticoids and IL-1 alpha, C3a is generated in the vicinity of the endothelial cell. This study further suggests that complement activation, with its deleterious consequences, may result from the stimulation of endothelium in situations where high levels of IL-1 alpha and endogenous glucocorticoids coexist, such as in septic shock.     

Effect of VEGF on Mouse Thymocyte Proliferation and Apoptosis <Emphasis Type="Italic">In Vitro</Emphasis>

Vascular endothelial growth factor is not only angiogenic, but also immunoregulatory factor. For evaluation of the possibility of its direct interaction with mouse thymocytes we studied the effect of vascular endothelial growth factor on proliferation and apoptosis of thymocytes and expression of genes for the corresponding receptor on these cells. Vascular endothelial growth factor modulated mitogen-induced proliferation of thymocytes and stimulated spontaneous apoptosis in intact thymus cells. Thymocytes express mRNA of type 2, but not type 1 vascular endothelial growth factor receptors.__________Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 5, pp. 533–537, May, 2005     

用Millicell底膜培养皿研究Tourmaline对ECV-304细胞增殖的影响

目的 用联合培养的方法研究Tourmaline对体外培养的人血管内皮细胞(ECV-304)增殖作用的影响。方法 用放置Tourmaline微球的Millicell底膜培养皿与人血管内皮细胞ECV304联合培养。通过细胞形态、细胞融合面积、细胞计数及增殖细胞核抗原(PCNA)的免疫细胞化学等方法观察培养细胞增殖的变化。结果 联合培养24h后Tourmaline组(与对照组比)细胞形态正常,呈铺路石样生长,贴壁细胞覆盖率从(79.50±5.92)％长到(90.17±3.49)％(P<0.05),细胞数增加(16.62±4.14)％(P<0.05),PCNA阳性细胞为(43.50±3.19)％,与对照组比,差异均有非常显著意义(P<0.01)。结论 Tourmaline可通过加强DNA合成,促进体外培养的ECV-304细胞增殖。