Effect of somatostatin and octreotide on proliferation and vascular endothelial growth factor secretion from murine endothelial cell line (HECa10) culture.

Angiogenesis, development of new blood vessels, is required for normal tissue repair and also for tumor cell proliferation, extracellular matrix invasion, and hematogenous metastases. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that has been shown to play a key role in neovascularization. Inhibition of angiogenesis in vitro and in vivo was documented by administration of native neuropeptide somatostatin and its analog octreotide. We have studied the effect of somatostatin-14 (SRIF) and ocreotide (sandostatin) on proliferation activity and VEGF release from cultured murine endothelial cells HECa10 in vitro. SRIF in concentrations from 10(-9) to 10(-5) M and ocreotide in concentrations from 10(-9) to 10(-5) M diminished the proliferative activity of cultured cells vs controls. SRIF and ocreotide in concentrations from 10(-14) to 10(-6) M did not change the release of VEGF into supernatants of 24 or 72 h endothelial cell cultures. Although we showed the antiproliferative effect of SRIF and ocreotide on mouse endothelial cells, we were unable to demonstrate the inhibitory effect of tested peptides on VEGF secretion in vitro.

Relations between Fc epsilon RI crosslinking-induced mast cell activation and adhesion to fibronectin.

Demonstration of murine mast cell adhesion to fibronectin (FN) following PMA-mediated cell activation raised the question whether crosslinking of high affinity IgE receptors on mouse mast cells might induce changes in adhesiveness of these cells to FN. Murine mast cells of line MCP5/L were used to investigate the effect of antigenic stimulation on cell adhesion to fN and mediator secretion. effect of antigenic stimulation on cell adhesion to FN and mediator secretion. Adhesion assays were performed using sensitized radiolabeled cells and FN- or BSA-coated 96-well plates. The presence of antigen in the concentrations up to 10 ng/ml resulted in concentration-dependent adhesion potentiation, which was detectable after 5 min, reached maximum at 30 min and persisted or decreased over the next 30 min. Adhesion potentiation decreased at antigen excess and was abolished by heat inactivation of IgE in the antiserum prior to cell treatment. External calcium ion and temperature dependence of adhesion together with the observation that RGD (Arg, Gly, Asp)--containing peptide blocked cell binding to FN suggests that FC epsilon RI crosslinking-induced adhesion potentiation involves an integrin type receptor on cell surface. Sensitized mast cells allowed to adhere spontaneously to FN released more histamine and beta-hexosaminidase upon antigen challenge. Hence, the results show the relations between IgE-induced mast cell activation, adhesion to FN and mediator secretion.

Influence of Tolpa Peat Preparation on the IgE-induced anaphylactic reactions in mice.

The ability of Tolpa Peat Preparation (TPP) to affect anaphylactic sensitization and mast cell secretory function was tested in BALB/c mice treated with TPP orally for 12 days. TPP in the doses of 20 and 50 mg/kg/day reduced histamine release from mouse peritoneal mast cells challenged with anti-IgE or concanavalin A in vitro. The treatment of mice with TPP from day 1 to day 12 of immunization with Ovalbumin (OA) absorbed on aluminium hydroxide gel resulted in a decrease of antigen-induced histamine release from mast cells of these mice in vitro and in decreased IgE antibody level in their sera. TPP introduced into OA-immunized mice showing developed IgE antibody response was less effective in decreasing anaphylactic histamine release from mast cells of these mice. In all experiments low doses of TPP used for oral treatment were more effective than high doses in inhibiting anaphylactic events in the mice.

Distribution of mast cells in human heart auricles and correlation with tissue histamine.

The mast cell density, fixation and staining properties, as well as tissue histamine, were studied in the human heart right auricles of 28 patients with mild atrial or ventricular septal defect (ASD or VSD respectively). We have found that different modes of fixation did not change significantly the mast cell appearance and number as stained with pinacyanol erythrosinate. The mast cell density was 21294 +/- 2775 cells per mm3 tissue and the mean histamine content of the auricle was 900.7 +/- 63.9 ng/g wet tissue weight. A significant positive correlation was observed between mast cell counts and histamine content (r = 0.79, p = 0.001). Furthermore, our data suggest the existence of a non-mast cell pool of cardiac histamine in man.