Augmentation of procoagulant activity in monokine stimulated human endothelial cells by calmodulin/protein kinase C inhibitors

Protein kinase C regulates cytokine-induced tissue factor transcription and procoagulant activity in human endothelial cells

Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) induce tissue factor in endothelium, which results in activation of the coagulation cascade. Despite extensive investigation, in which various stimuli that induce tissue factor have been defined, the intracellular processes that control tissue factor expression are not well understood. It has been proposed that protein kinase C regulates tissue factor expression primarily because phorbol myristate acetate, the protein kinase C activator, induces tissue factor expression. In this study we examined whether IL-1 alpha- or TNF-alpha-stimulated tissue factor production is regulated through a protein kinase C-dependent mechanism. Northern blot analysis showed that cytokine-induced tissue factor mRNA was significantly reduced in human umbilical vein endothelial cells treated with calphostin C, a specific protein kinase C inhibitor. Tissue factor functional activity was decreased in the presence of calphostin C as well. Calphostin C also inhibited phorbol myristate acetate-induced tissue factor expression. In contrast, calphostin C did not alter cytokine induction of E-selectin or prostacyclin release. Because calcium stimulates protein kinase C binding to the membrane and its resulting catalytic activity, human umbilical vein endothelial cells were exposed to IL-1 alpha or TNF-alpha in the presence of calcium ionophore A23187. A23187 had little effect alone but significantly augmented cytokine stimulation of tissue factor mRNA. Okadaic acid, a phosphatase inhibitor, increased cytokine-induced tissue factor mRNA compared with cytokine alone, which suggests that a phosphorylation event is important in tissue factor expression. These results indicate that protein kinase C is involved in cytokine activation of endothelial cell tissue factor expression.

Effective combination chemo/hormonal therapy for malignant melanoma: experience with three consecutive trials

Our experience with the combination of dacarbazine, carmustine, cisplatin with and without tamoxifen is reported. In our initial study, with all 4 drugs, we had an overall response rate of 50% with a complete response rate of 15%. Due to a high incidence of deep venous thrombosis and the lack of effectiveness of tamoxifen as a single agent, we deleted tamoxifen from the regimen and treated another 20 patients. Surprisingly, the response rate decreased to 10%. We then re-incorporated tamoxifen into the regimen and treated 25 additional patients. In this third group of patients we experienced an objective response rate of 52% with a complete response rate of 8%. Overall, 65 patients have been treated: 45 with and 20 without tamoxifen. Twenty-three (51%) patients treated with tamoxifen have responded, with 5 (11%) patients achieving a complete response. Only 2 (10%) patients treated without tamoxifen have responded. Despite the improvement in the response rate, a corresponding increase in survival has not been seen. Patients treated with tamoxifen had a mean survival of 10.8 (SD 13.6) months compared with a mean survival of 9.8 (SD 7.3) months for those treated without tamoxifen. The absence of survival advantage for the tamoxifen-treated patients may be due to early failure in the central nervous system. In 48% of the responding tamoxifen-treated patients, the first site of failure was the central nervous system, while systemic disease was still responding.

Cultivation of human dermal microvascular endothelial cells in vitro: immunocytochemical and ultrastructural characterization and effect of treatment with three synthetic retinoids

A new reliable and reproducible technique to culture endothelial cells from the small vessels and capillaries of human skin is introduced, and proliferation and differentiation of the growing cells are characterized. The endothelial origin of the culture cells was confirmed by light- and electron microscopy and by labelling with Ulex europaeus Agglutinin I and an antibody against Factor VIII-related antigen. Further immunocytochemical characterization showed that 92-100% of the cells were positive for beta 2-microglobulin and the entire cell population expressed vimentin, whereas cytokeratins, desmin, HLA-DR antigen, Leu 6 and S 100 protein, could not be detected. As vascular endothelium is a common site of inflammation and retinoids have been shown to be of good clinical efficacy in some chronic inflammatory skin diseases, we investigated the influence of etretinate, etretin and isotretinoin on proliferation and antigen expression of our culture cells. All retinoids applied inhibited proliferation of endothelial cells in a dose- and time-dependent manner whereas they induced neither HLA-DR nor intercellular adhesion molecule-1 (ICAM-1). Furthermore, none of the retinoids applied influenced the gamma-interferon-induced expression of these surface antigens on endothelial cells. Our results suggest that the action of retinoids in skin inflammation is not mediated by modulation of HLA-DR or ICAM-1. The cell culture technique described here is an interesting and reliable model for studying the influence of drugs on endothelial cell growth and differentiation in vitro.

Endotoxin-mediated bovine alveolar macrophage procoagulant induction is dependent on protein kinase C activation

The induction of pulmonary alveolar macrophage (PAM) tissue factor-dependent procoagulant activity is central to the deposition of inflammatory fibrin in the pulmonary alveolus. The presence of enhanced tissue factor activity is often associated with pulmonary fibrin deposition, an important pathogenetic event that can delay resolution of pulmonary inflammation and promote the induction of pulmonary fibrosis. Since tissue factor synthesis induction and activation pathways are potential therapeutic targets for modulation of alveolar macrophage tissue factor (procoagulant) activity, we examined the pathways through which endotoxin lipopolysaccharide (LPS) induces bovine PAM tissue factor-dependent procoagulant activity. PAM procoagulant activity was markedly enhanced to 10 times the levels of freshly isolated PAM after 8 h of culture in the presence of either the protein kinase C (PKC) agonist phorbol 12-myristate 13-acetate (PMA) or LPS. Both LPS-(P less than 0.002) and PMA-induced activity (P less than 0.007) was completely ablated by the PKC inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H 7,100 microM) but was unaffected by the cyclic nucleotide-dependent protein kinase inhibitor N-(2-guanidinoethyl)-5-isoquinolinesulfonamide (HA-1004, 100 microM). The arachidonate cyclooxygenase pathway inhibitor phenylbutazone (10(-4) M) had modest effects that were not statistically significant. The unstimulated increase of procoagulant activity in 8-h cultures was unaffected by the same inhibitory modulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor enhances expression of tissue factor mRNA in endothelial cells

We have examined the effect of recombinant tumor necrosis factor on the expression of tissue factor activity and tissue factor mRNA levels in vascular endothelial cells. Following exposure of human umbilical vein endothelial cells to this cytokine, the appearance of tissue factor procoagulant activity was detected following cell disruption, and was maximal at 6 hours. Northern blot analysis of cytokine-treated cells demonstrated a similar increase in the synthesis of tissue factor mRNA, followed by a gradual decline to the basal level by 18 hours. Cycloheximide by itself induced the accumulation of high levels of tissue factor mRNA in these cells. This result suggests that the proteins necessary for transcription of the tissue factor gene are present in the endothelial cell prior to cytokine stimulation, and synthesis of the tissue factor mRNA may be controlled, in part, by a labile repressor protein.

A novel microtiter plate assay for the quantitation of procoagulant activity on adherent monocytes, macrophage and endothelial cells

The interaction of monocytes, macrophages and endothelial cells with inflammatory agents induces cell surface changes resulting in the activation of the coagulation cascade. A large volume 96 well plate microtiter assay has been developed which permits the quantitation of procoagulant activity on endotoxin stimulated cells without requiring the use of purified coagulation factors. Procoagulant activity is measured through a two stage amidolytic assay using commercially available Proplex as a source of factors VII and X and the chromogenic substrate S2222. The assay is rapid, linear, and sensitive as procoagulant activity can be detected on as few as 5 X 10(3) monocytes or macrophages and 3 X 10(2) endothelial cells.