Plasma markers of endothelial dysfunction in pulmonary hypertension.

STUDY OBJECTIVES: To evaluate and to correlate endothelial cell dysfunction, using recently available plasma markers, with the magnitude of pulmonary artery pressure in patients with severe pulmonary hypertension (PH). DESIGN: Selected plasma markers of endothelial cell dysfunction were studied: nitric oxide (NO), thrombomodulin, tissue factor pathway inhibitor, and soluble endothelium, leukocyte, and platelet selectins (sE-, sL-, sP-selectins, respectively). SETTING: Padova University Hospital and Department of Pathology and Pharmacology, Loyola University of Chicago, Chicago, IL. PATIENTS: Fifteen patients had severe PH (four men and 11 women; mean age, 49.7 +/- 2.9 years: seven patients had primary pulmonary hypertension [PPH] and eight patients had secondary pulmonary hypertension [SPH]), and 20 patients were healthy control subjects. MEASUREMENT AND RESULTS: In patients with PH, sP- and sE-selectins were elevated, whereas sL-selectin was lower in comparison with the selectin levels in control subjects. However, the differences between patients with PH and control subjects were significant only for sL-selectin (p < 0.0001) and sE-selectin (p < 0.03). The NO level was significantly lower in patients with PH compared with the NO level in control subjects (p < 0.01). No difference in tissue factor pathway inhibitor level was noted between control subjects and patients with PH. Only a weak correlation was found between thrombomodulin plasma levels and magnitude of systolic pulmonary artery pressure (r = -0.528, p < 0.05). CONCLUSIONS: Our data are in keeping with the evidence for significant endothelial cell dysfunction in patients with PH and the need for chronic anticoagulation believed to increase survival in these patients. In addition, these data seem to suggest a need for newer agents that are able to increase the antithrombotic endothelial function.

Plasma markers of endothelial dysfunction in chronic obstructive pulmonary disease.

We studied some endothelial cell activity plasma markers, nitric oxide (NO), thrombomodulin (TM), selectins (sP-, sE-, sL-selectin: platelet-P, endothelium-E, leukocyte-L), and tissue factor pathway inhibitor (TFPI) in 14 patients with chronic obstructive pulmonary disease (COPD), matched with 20 normal controls, to evaluate their endothelial cell dysfunction. Both NO (patients: 23.42 +/- 1.67 microg/mL: controls: 40.0 +/- 3.38 microg/mL) and TM levels (patients: 5.46 +/- 1.32 ng/mL; controls: 12.9 +/- 0.51 ng/mL) were significantly decreased in COPD (p < 0.001). sP-selectin levels (patients: 79.42 +/- 18.20 ng/mL, controls: 37.5 +/- 2.84 mg/mL) were significantly higher (p < 0.02), whereas sL-selectin levels (patients: 584.9 +/- 78.98 ng/mL, controls: 1,054.02 +/- 61.28 ng/mL) were significantly decreased in patients with COPD (p < 0.001). In contrast, no differences were seen in sE-selectin. Patients with COPD showed a significantly higher (p < 0.001) TFPI antigen plasma level (mean 112.28 +/- 6 .45 ng/mL; controls 77.68 +/- 0.28 ng/mL) than controls. Our data support the concept of some form of endothelial cell dysfunction, and coagulation abnormalities are present in patients with COPD. However, because the endothelium seems to produce a defense mechanism, the potential usefulness of an antithrombotic therapy in these patients needs further investigation.

Tissue factor pathway inhibitor release induced by defibrotide and heparins.

We evaluated the release of tissue factor pathway inhibitor (TFPI) induced by defibrotide (DF), a single-stranded, negatively charged polydeoxyribonucleotide extracted from mammalian organ. Ten normal volunteers were injected with an intravenous bolus of 400 mg DF and 2,000 IU unfractionated heparin (UFH). In addition, three volunteers were also injected with an intravenous bolus of 2,000 anti-Xa U of two low-molecular-weight heparins (LMWHs), enoxaparin and nadroparin. UFH caused a 4-fold increase in plasma TFPI at 5 minutes, with a decrease that was parallel to the heparin level measured by the anti-Xa assay. However, at 80 minutes, although the plasma anti-Xa activity of UFH was almost undetectable, the level of TFPI remained 2-fold baseline. DF induced an increase of TFPI that was 2-fold higher than the baseline level, with a steady state achieved between 5 and 20 minutes. At 40 minutes, the TFPI levels returned to basal level. This pattern was not coincident with the clearance of DF and at 40 minutes, the concentration of DF was still one third of the levels at 5 minutes (25.4 +/- 4.04 microg/mL). Both of the LMWHs induced a similar TFPI peak level at 5 minutes (1.5-fold increase) and at 40 minutes the TFPI levels returned to the initial levels. At 5 minutes, both LMWHs showed a higher plasma anti-Xa activity than UFH, which was detectable even at 80 minutes. The current study demonstrated that one of the mechanisms of the antithrombotic activity of DF is mediated via TFPI. Furthermore, the release of TFPI by heparin is mediated by non-antithrombin III binding fragments. Thus, polyanionic electrolytes are capable of releasing TFPI irrespective of their antithrombin III effect.

NF-Y mediates the transcriptional inhibition of the cyclin B1, cyclin B2, and cdc25C promoters upon induced G2 arrest.

During normal cell cycles, the function of mitotic cyclin-cdk1 complexes, as well as of cdc25C phosphatase, is required for G2 phase progression. Accordingly, the G2 arrest induced by DNA damage is associated with a down-regulation of mitotic cyclins, cdk1, and cdc25C phosphatase expression. We found that the promoter activity of these genes is repressed in the G2 arrest induced by DNA damage. We asked whether the CCAAT-binding NF-Y modulates mitotic cyclins, cdk1, and cdc25C gene transcription during this type of G2 arrest. In our experimental conditions, the integrity of the CCAAT boxes of cyclin B1, cyclin B2, and cdc25C promoters, as well as the presence of a functional NF-Y complex, is strictly required for the transcriptional inhibition of these promoters. Furthermore, a dominant-negative p53 protein, impairing doxorubicin-induced G2 arrest, prevents transcriptional down-regulation of the mitotic cyclins, cdk1, and cdc25C genes. We conclude that, as already demonstrated for cdk1, NF-Y mediates the transcriptional inhibition of the mitotic cyclins and the cdc25C genes during p53-dependent G2 arrest induced by DNA damage. These data suggest a transcriptional regulatory role of NF-Y in the G2 checkpoint after DNA damage.

The role of wild-type p53 in the differentiation of primary hemopoietic and muscle cells.

Experiments previously performed on 32D and C2C12 cell lines indicated that wild type p53 (wtp53) protein has a role in granulocyte and myotube differentiation. Since these are immortal cells, we asked whether the inhibition of differentiation induced by the expression of dominant-negative p53 (dnp53) proteins was dependent on the immortalization-determined microenvironment. Thus, we evaluated the effects produced by interfering with the endogenous p53 gene in murine primary hemopoietic and muscle cells. Expression of dnp53 protein reduced the differentiation of bone marrow cells into granulocytes and macrophages. Moreover, p53 activation was measurable during the differentiation process of primary myoblasts, while interference with this activation led to a consistent slow down of terminal differentiation. Since the impairment of the differentiation was not accompanied by alterations in the cell cycle withdrawal and in the rate of apoptosis which are coupled with these types of differentiation, the data here reported support a specific role for p53 in the differentiation process. However, the difference in the intensity of inhibition between immortal and primary cells, i. e., complete versus slow down, respectively, suggests that the immortalization process might render the cells more sensitive to the loss of wtp53 activity for the differentiation process.

Tissue factor pathway inhibitor (TFPI) antigen plasma level in patients with interstitial lung disease before and after heparin administration.

The extrinsic pathway is probably the predominant pathway in initiating blood coagulation in inflammatory lung diseases. Tissue factor pathway inhibitor (TFPI) is a Kunitz-type protease inhibitor of factor VIIa/tissue factor in the presence of factor Xa. As it has been shown recently that TFPI plasma levels are increased under acute inflammatory conditions, we studied TFPI antigen plasma levels before and after injecting 20 IU/kg body weight of unfractionated heparin into 49 patients with different stages of sarcoidosis, into 9 with idiopathic pulmonary fibrosis, and into 15 normal controls. TFPI, before injecting heparin, was significantly increased in all sarcoidosis stages (stage I: 97.6 +/- 6.4 ng/mL; stage II: 116.2 +/- 11.9 ng/mL; stage III: 116.3 +/- 7.3 ng/mL) and in idiopathic pulmonary fibrosis (116.8 +/- 16.1 ng/mL), as compared to the control group (77.7 +/- 3.3 ng/mL). No correlation was found between the intensity of the activity of sarcoidosis, measured as BAL white cell count, and TFPI. Five minutes after heparin administration the rise in TFPI was lower, although not statistically significant, in all sarcoidosis stages than in controls. In contrast, idiopathic pulmonary fibrosis had a similar or even higher TFPI elevation than the control group. In sarcoidosis the elevated TFPI and the lower capacity by endothelial cells to release TFPI after heparin may represent a compensatory mechanism to prevent blood clotting and/or the endothelial cell dysfunction of the microvasculature in this condition. In contrast, the extensive mesenchymal cell proliferation present in idiopathic pulmonary fibrosis could explain our findings, as it has been shown that cultured human mesangial cells produce and release TFPI.