Hepatocyte growth factor enhances MMP activity in human endothelial cells

Scatter factor (SF) or hepatocyte growth factor (HGF) has been identified as an angiogenic factor. Angiogenesis requires not only tube formation but also invasion of pericytes and extracellular matrix (ECM) remodeling to promote new vessel stabilization. In the current study, the effect of SF/HGF on endothelial cell (EC) production of matrix metalloproteinases (MMPs) was explored. We showed that SF/HGF enhanced MT1-MMP synthesis and induced MMP-2 activation in two human EC lines: dermal microvessel EC and coronary arterial EC. Furthermore, SF/HGF accelerated EC invasion into matrix, an activity that could be inhibited by a MMP inhibitor. We also demonstrated that the MAP kinase cascade is critical in signal transduction pathway from SF/HGF stimulation to MT1-MMP up-regulation. The current study indicates that MMP activation is a novel effect of SF/HGF on ECs.

alpha-melanocyte-stimulating hormone as a mediator of tolerance induction

There is accumulating evidence for a strong interaction between components of the nervous system and the immune system. Accordingly, specific receptors for neuropeptides were found to be expressed on immunocompetent cells and several neuropeptides were recognized as potent regulators of immune and inflammatory reactions. Among various neuropeptides such as substance P, calcitonin gene-related peptide and others alpha-melanocyte-stimulating hormone (alpha-MSH) was found to be produced in the skin. Moreover, melanocortin receptor 1 which is specific for alpha-MSH and ACTH is expressed in the skin on keratinocytes, dendritic cells, macrophages and endothelial cells. In monocytes, macrophages and dendritic cells alpha-MSH inhibits the production and activity of immunoregulatory and proinflammatory cytokines such as IL-2, IFNgamma and IL-1. It downregulates the expression of costimulatory molecules such as CD86 and CD40 and induces the production of suppressor factors such as the cytokine synthesis inhibitory factor IL-10. On endothelial cells alpha-MSH is capable of downregulating the LPS-induced expression of adhesion molecules such as vascular cellular adhesion molecules and E-selectin. Moreover, the LPS-induced activation of transcription factors such as NFkappaB is downregulated by alpha-MSH. In a mouse model intravenous or topical application of alpha-MSH was found to inhibit the induction as well as the effector phase of a contact hypersensitivity reaction and to induce hapten-specific tolerance. Moreover, there is evidence that the N-terminal tripeptide of alpha-MSH is sufficient for its in vitro and in vivo immunomodulatory effects. These findings indicate that the production of immunosuppressing neuropeptides such as alpha-MSH by epidermal cells may play an essential role during the pathogenesis of immune and inflammatory reactions in the skin.

[Experimental study on revascularization of subdermal vascular network thin flap]

OBJECTIVE

To investigate the survival mechanism of subdermal vascular network thin flap (SVNF).

METHODS

24 rabbits were divided into three groups, in which the SVNF, subdermal vascular network skin graft and the traditional random flap were created respectively. Tissue hyalinization technique was used to find out the differences of vascular architecture between the three groups at the 1st-7th day, and the 14th day postoperatively.

RESULTS

The results showed that the blood supply reestablished earlier in SVNF group than the other two groups.

CONCLUSION

There is a zone of rapid and intensive angiogenesis in the mid-part of SVNF known as "intermediary pedicle". This is the anatomic basis of the early pedicle division and superior survival ratio of SVNF.

Eotaxin and RANTES expression by the dermal endothelium is associated with eosinophil infiltration after ivermectin treatment of onchocerciasis

The roles of eotaxin, RANTES, and MCP-3 expression in eosinophil recruitment to the site of parasite killing that occurs following ivermectin treatment of onchocerciasis were assessed in the skin of 13 Onchocerca volvulus-infected subjects and two noninfected controls before and after ivermectin treatment. Adverse reactions in infected subjects were associated with the appearance of eosinophils in the dermis as part of a perivascular inflammatory infiltrate. Although no expression of RANTES and eotaxin was seen in dermal vascular endothelial cells in biopsies taken before treatment (nor at any time in the skin of uninfected controls), endothelial expression of both eotaxin and RANTES was noted by 24 h following treatment. While RANTES expression was transient, eotaxin expression increased in parallel with increasing eosinophil recruitment up to 60 h posttreatment. These observations indicate that endothelial expression of eotaxin and RANTES may have an important role in eosinophil recruitment into the skin during helminth-killing reactions.

Homeobox B3 promotes capillary morphogenesis and angiogenesis

Endothelial cells (EC) express several members of the Homeobox (Hox) gene family, suggesting a role for these morphoregulatory mediators during angiogenesis. We have previously established that Hox D3 is required for expression of integrin alphavbeta3 and urokinase plasminogen activator (uPA), which contribute to EC adhesion, invasion, and migration during angiogenesis. We now report that the paralogous gene, Hox B3, influences angiogenic behavior in a manner that is distinct from Hox D3. Antisense against Hox B3 impaired capillary morphogenesis of dermal microvascular EC cultured on basement membrane extracellular matrices. Although levels of Hox D3-dependent genes were maintained in these cells, levels of the ephrin A1 ligand were markedly attenuated. Capillary morphogenesis could be restored, however, by addition of recombinant ephrin A1/Fc fusion proteins. To test the impact of Hox B3 on angiogenesis in vivo, we constitutively expressed Hox B3 in the chick chorioallantoic membrane using avian retroviruses that resulted in an increase in vascular density and angiogenesis. Thus, while Hox D3 promotes the invasive or migratory behavior of EC, Hox B3 is required for the subsequent capillary morphogenesis of these new vascular sprouts and, together, these results support the hypothesis that paralogous Hox genes perform complementary functions within a particular tissue type.

Primary localized cutaneous amyloidosis--lichen amyloidosus. A case report

We report a case of primary localized cutaneous amyloidosis-lichen amyloidosus in a 55-year-old man. Immunohistochemistry using antibodies against cytokeratin and AL immunoglobulins revealed the presence of both components in amyloid foci located subepidermally, mainly in dermal papillae. The results of histochemical reactions confirm the keratin-derived nature of amyloid in primary cutaneous amyloidosis.

Effect of hyperoxia and hypoxia on subcutaneous tissue gases and pH. An experimental study in pigs

The effect of different fractions of inspired oxygen on subcutaneous oxygen tension, carbon dioxide tension and pH in relation to arterial and mixed venous blood gases and pH and hemodynamic variables was evaluated in 13 domestic pigs. Subcutaneous, arterial and mixed venous oxygen tensions were closely correlated (r = 0.94). A minor significant increase in subcutaneous carbon dioxide tension was noted during hyperoxia (p < 0.05). A major increase (33%) was noted during the last step of hypoxia, when arterial and mixed venous carbon dioxide tensions increased only 12 and 17%, respectively. A minor decrease in subcutaneous pH was noted during hyperoxia (p < 0.05) and a major decrease during hypoxia (p < 0.05). Measurements of subcutaneous tissue gases and pH are indicators of oxygen utilization during hyper- and hypoxia.

Three-dimensional reconstruction of blood vessels from in vivo color Doppler optical coherence tomography images

PURPOSE

Current laser treatment for vascular disorders such as port wine stains can have incomplete or unacceptable results. A customized treatment strategy based on knowledge of the patient's blood vessel structure may effect an improved clinical outcome.

PROCEDURE

We tested the feasibility of using color Doppler optical coherence tomography (OCT) and image processing techniques to locate, measure and reconstruct cutaneous blood vessels in rat and hamster skin. OCT is a recent, potentially noninvasive technique for imaging subsurface tissue structures with micrometer scale resolution.

RESULTS

Blood vessels were identified in a series of cross-sectional images, then a three-dimensional reconstruction was made. Parameters that can affect optimum laser treatment parameters, such as average blood vessel depth and luminal diameter, were found from the images.

CONCLUSION

This study shows that color Doppler OCT is a potential tool for improving laser treatment of vascular disorders.

Propionyl-L-carnitine dilates human subcutaneous arteries through an endothelium-dependent mechanism

PURPOSE

The vasoactive effects of propionyl-L-carnitine (PLC) on human arteries, including endothelial and smooth muscle cell influences, were studied.

METHODS

Small (less than 200 microm) subcutaneous fat arteries (n = 19), obtained from human patients undergoing vascular surgery, were dissected and mounted in an arteriograph system that allowed measurement of lumen diameter and control of transmural pressure. To investigate the role of the endothelium, arteries were compared intact, intact and in the presence of either 0.3 mmol/L nitro-L-arginine (an inhibitor of nitric oxide synthesis) or 10 micromol/L indomethacin (an inhibitor of prostaglandin synthesis), or denuded of endothelium. After a 1-hour equilibration at a pressure of 50 mm Hg, arteries were precontracted 50% with an intermediate concentration of norepinephrine, and clinically relevant concentrations of PLC (0.1 to 100 micromol/L) were cumulatively added to the bath while the lumen diameter was continually measured.

RESULTS

Intact arteries dose-dependently dilated to PLC, with the half maximal dilation occurring at 2.9 +/- 1.2 micromol/L, increasing diameter 91% +/- 5% at 100 micromol/L. In contrast, PLC had significantly less effect on deendothelialized arteries, increasing diameter only 24% +/- 11% at 100 micromol/L (P <.01 vs. intact). This indicates the endothelial dependency of this compound. Blockade of nitric oxide did not inhibit this vasodilation, with the half-maximal response occurring at 8.6 +/- 7 micromol/L, increasing diameter 85% +/- 8% at 100 micromol/L ( P >.05 vs. intact). However, this vasodilation was significantly diminished in the presence of indomethacin, which dilated arteries only 53% +/- 18% at 100 micromol/L (P <.01 vs. intact; P >.05 vs. denuded).

CONCLUSION

PLC is an endothelium-dependent vasodilator, the mechanism of which is partially mediated by prostaglandin synthesis, not nitric oxide. The beneficial effects of this compound may, in part, be related to vasodilation and enhanced blood flow.

[Multinucleate cell angiohistiocytoma]

INTRODUCTION

Multinucleate cell angiohistiocytoma is a rare benign vascular proliferation. We report a case.

CASE REPORT

A 75-year-old woman presented violaceous papules on the right thigh. Histological examination showed a proliferation of small blood vessels with multinucleated cells in the dermis and confirmed the diagnosis of multinucleate cell angiohistiocytoma.

DISCUSSION

Multinucleate cell angiohistiocytoma is a rare benign vascular tumor first described in 1985 often confused with Kaposi's sarcoma. Clinically it is characterized by violaceous papules on acral sites and face in elderly women. Histological examination shows an increased number of blood vessels together with mononucleated and multinucleated histiocyte-like cells in the dermis. Reviewing the literature we describe the main clinical and histopathologic features of this disorder.

Increased dermal angiogenesis after low-intensity laser therapy for a chronic radiation ulcer determined by a video measuring system

Acute and chronic radiation-induced dermatitis can occur after high doses of ionizing radiation of the skin. We describe a patient with a long-lasting radiotherapy-induced ulcer that healed after low-intensity laser therapy. A video measuring system was used to determine the number of dermal vessels in the ulcer before and after laser treatment. We found a statistically significant increase in the number of dermal vessels after low-intensity laser therapy in both the central and marginal parts of the ulcer compared with its pretreatment status.

Iontophoretic current and intradermal microdialysis recovery in humans

When microdialysis (MD) is used to study dermal delivery by iontophoresis, the effects of current may alter MD recovery through an increase in temperature, a change of pH, hyperemia, and dermal hydration. The objective of this work is to assess whether these effects of current may cause a measurable change in the retrodialysis of a model compound (sodium fluorescein, Fl). Two linear MD-probes were inserted in the forearm dermis of healthy human volunteers and perfused with Ringer's solution containing Fl. Two identical iontophoresis chambers (IC, filled with NaCl in propylene glycol) were placed over the MD-probes. Each IC included a laser Doppler flowmetry probe to monitor skin blood flow. At one IC, current was applied for two periods of 30 min each, separated by 30 min of no current. No current was applied to the control site. Dialysate samples were collected every 5 min and analyzed for Fl by HPLC. Skin blood flow increased in response to iontophoresis, on average, 570% compared to the control site. However, there was no difference in the recovery of Fl between the current-active site versus the control site, and between the period with applied current versus the period with no current. In conclusion, iontophoretic current did not affect intradermal MD recovery.

Exogenous non-crosslinked collagen enhances granulation tissue formation in dermal excision wounds in guinea pigs

Based on previous observations indicating a role for collagen peptides in eliciting a positive feedback for collagen biosynthesis, this study was initiated to elucidate the effect of non-crosslinked collagen on granulation tissue formation in dermal excision wounds. The wounds were treated with either non-crosslinked or crosslinked native collagen, or left untreated as controls. Granulation tissue was analyzed for collagen type I mRNA, for levels of interstitial collagen and for the number of blood vessels. The results indicated significant increases in procollagen type I mRNA, in interstitial collagen, in the number of blood vessels and in epithelial advance in the non-crosslinked collagen-treated wounds relative to the untreated controls. It is assumed that the presence of non-crosslinked collagen in a healing wound enhances both procollagen type I biosynthesis and the repair process of dermal wounds, due to the more readily released collagen peptides derived from this exogenous collagen dressing.

Diabetic pigmented spots on the extrapretibial region: immunohistochemical study of type IV collagen in dermal vessel wall

A case of diabetes mellitus associated with multiple pigment spots is reported. The patient had multiple pigmented atrophic patches on the abdominal area and thighs. There were no pigmented spots on the pretibial area. Histologically, dermal vessels showed intimal thickening and deposition of periodic acid-Schiff (PAS)-positive fibrillar material in vessel walls. Clinical and histological features indicated that these pigment spots were diabetic pigmented pretibial patches occurring in the extrapretibial area. Immunohistochemical studies of lesional and non-lesional skin using the antibodies for alpha1-alpha6 chains of type IV collagen revealed that PAS-positive material of vessel walls in both lesional and non-lesional skin was stained with alpha1 and alpha2 chain antibodies but not with alpha3-alpha6 chain antibodies, indicating that alpha1 and alpha2 chains of type IV collagen, which are normal components of the dermal vessel basement membrane, accumulate in the vessel walls in diabetes mellitus.

Induction of apoptosis in human dermal microvascular endothelial cells and infantile hemangiomas by interferon-alpha

BACKGROUND

Hemangioma of infancy is an angiomatous disorder characterized by the proliferation of capillary endothelium. It has been shown that interferon-alpha (IFN-alpha) may induce involution of proliferating, life-threatening hemangiomas in children. This IFN-alpha-induced regression of hemangiomas is not accompanied by any T cell response nor by the occurrence of necrosis.

METHODS

To determine whether IFN-alpha may induce apoptosis, we cultured human dermal microvascular endothelial cells (HDMEC) with IFN-alpha at concentrations of 100, 500, 1,000 and 2,000 U/ml for 24-72 h and detected apoptosis by terminal deoxynucleotidyl transferase mediated FITC-dUTP nick end labeling (TUNEL). Quantitative analysis was performed using the FACScan and morphological alterations were studied by confocal laser scanning microscopy. In addition to the in vitro study we also analyzed frozen skin sections from proliferating, spontaneously regressing, and IFN-alpha-treated hemangiomas by simultaneous determination of endothelial cells and apoptotic nuclei using an indirect immunofluorescence test in combination with TUNEL.

RESULTS

Apoptosis was detected in up to 20% of the IFN-alpha-treated endothelial cells compared to the untreated controls. A maximum of apoptosis was observed after 48 h of stimulation with IFN-alpha in a dose-dependent manner. The analysis of hemangioma biopsies revealed apoptotic endothelial cells in IFN-alpha-treated as well as in spontaneously regressing hemangiomas, but not in proliferating ones.

CONCLUSION

These data indicate that the therapeutic effect of IFN-alpha on hemangiomas is based on apoptosis induction of endothelial cells, which might also explain the clinically and histologically observed involution without any sign of inflammation or necrosis.