Tumor necrosis factor increases the production of plasminogen activator inhibitor in human endothelial cells in vitro and in rats in vivo

The vascular endothelium plays an important role in fibrinolysis by producing tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI). The monokine tumor necrosis factor (human recombinant TNF) increased the production of PAI by cultured human endothelial cells from umbilical vein (twofold) and from foreskin microvessels (four to eight fold). This was demonstrated by titration of endothelial cell-conditioned medium with t-PA, by reverse fibrin autography, and by immunoprecipitation of [35S]PAI-1 by anti-PAI-1 IgG. TNF also induced a marked increase in PAI-1 messenger RNA (mRNA) in the cells. The stimulation of PAI activity by TNF was seen at 4 U/mL and reached a maximum at 500 U/mL. Human recombinant lymphotoxin and interleukin-1 (α and β) also stimulated the production of PAI activity, while interleukin-6 was ineffective. Separate additions of TNF or interleukin-1 (IL-1) at optimal concentrations (500 U/mL and 5 U/mL, respectively) resulted in a comparable stimulation of PAI production by endothelial cells. The simultaneous addition of both mediators resulted in an additive effect. The effect of TNF could not be prevented by the addition of polymyxin B or by anti-IL-1 antibodies. Therefore, it is unlikely that TNF acts through the induction of IL-1 secretion by endothelial cells. Two hours after a bolus injection of 250,000 U/kg TNF into rats, a fivefold increase in circulating PAI levels was found. In the next ten hours, the levels returned to normal. Blood platelets do not significantly contribute to the increase in circulating PAI, because the number of platelets did not change after TNF injection and the amount of PAI in blood platelets is not sufficient for several hours during an increase in PAI activity. The acute phase reactants, fibrinogen and α2-antiplasmin in rat plasma, were altered little if any two to 24 hours after injection of 250,000 U/kg TNF. In vitro, TNF did not change PAI production by human and rat hepatocytes in primary monolayer culture. Therefore, it is most likely that vascular endothelial cells contribute to the increased amount of circulating PAI induced by TNF in vivo. This increase in PAI activity might decrease fibrinolysis. Chemicals/CAS: plasminogen activator inhibitor, 105844-41-5; Glycoproteins; Lymphotoxin; Plasminogen Inactivators; RNA, Messenger; Tissue Plasminogen Activator, EC 3.4.21.68; Tumor Necrosis Facto

A role for the fibrinolytic system in postsurgical adhesion formation

To look for evidence of a fibrinolytic insufficiency as a cause of adhesion formation. Retrospective and prospective study. University medical center. Retrospective study: 50 patients undergoing laparoscopy, divided into patients with and without endometriosis. Prospective study: 18 patients undergoing infertility surgery involving a second-look laparoscopy. During all surgical procedures, adhesions were scored, and peritoneal fluid and plasma were collected. Parameters of the fibrinolytic system were measured to establish a possible relation with the presence and formation of adhesions. In patients with endometriosis and adhesions, significantly higher peritoneal fluid concentrations were found for plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA), and plasminogen, compared with patients with endometriosis but without adhesions. In the prospective study, initial peritoneal PAI-1 concentrations correlated significantly with the extent of adhesion formation (r(s) = 0.49) and adhesion-improvement scores (r(s) = -0.52). Also, the change in concentration of tPA and fibrinogen from the initial surgical procedure to the second-look laparoscopy correlated significantly with adhesion-improvement scores (DeltatPA: r(s)= 0.50; Deltafibrinogen: r(s) = -0.64). This first prospective study in humans adds further weight to the hypothesis that adhesions are caused by an insufficiency in peritoneal fibrinolytic activity. Plasminogen activator inhibitor-1 is a potential marker for the identification of patients at risk for developing adhesion

Rosuvastatin reduces atherosclerosis development beyond and independent of its plasma cholesterol-lowering effect in APOE*3-Leiden transgenic mice - Evidence for antiinflammatory effects of rosuvastatin

Background-Statins can exert anti-inflammatory antiatherosclerotic effects through an anti-inflammatory action, independent of lowering cholesterol. We addressed the question whether the anti-inflammatory activities of statins can reduce atherosclerosis beyond the reduction achieved by cholesterol lowering per se. Methods and Results-Two groups of 20 female APOE*3-Leiden mice received either a high-cholesterol diet (HC) or a high-cholesterol diet supplemented with 0.005% (wt/wt) rosuvastatin (HC+R). The HC diet alone resulted in a plasma cholesterol concentration of 18.9+/-1.4 mmol/L, and administration of rosuvastatin lowered plasma cholesterol to 14.1+/-00.7 mmol/L. In a separate low-cholesterol (LC) control group, the dietary cholesterol intake was reduced, which resulted in plasma cholesterol levels that were comparable to the HC+R group (13.4+/-0.8 mmol/L). Atherosclerosis in the aortic root area was quantified after 24 weeks. As compared with the HC group, the LC group had a 62% (P <0.001) reduction in cross-sectional lesion area. When compared with the LC group, the HC+R group showed a further decrease in cross-sectional lesion area (80%, P <0.001), size of individual lesions (63%, P <0.05), lesion number (58%, P <0.001), monocyte adherence (24%, P <0.05), and macrophage-containing area (60%, P <0.001). Furthermore, rosuvastatin specifically suppressed the expression of the inflammation parameters MCP-1 and TNF-alpha in the vessel wall and lowered plasma concentrations of serum amyloid A and fibrinogen, independent of its cholesterol-lowering effect. Conclusions-Rosuvastatin reduces atherosclerosis beyond and independent of the reduction achieved by cholesterol lowering alone. This additional beneficial effect of rosuvastatin may be explained, at least partly, by its anti-inflammatory activit

Dietary sphingolipids lower plasma cholesterol and triacylglycerol and prevent liver steatosis in APOE*3Leiden mice

The prevalence of dyslipidemia and obesity resulting from excess energy intake and physical inactivity is increasing. The liver plays a pivotal role in systemic lipid homeostasis. Effective, natural dietary interventions that lower plasma lipids and promote liver health are needed. Our goal was to determine the effect of dietary sphingolipids on plasma lipids and liver steatosis. APOE*3Leiden mice were fed a Western-type diet supplemented with different sphingolipids. Body cholesterol and triacylglycerol metabolism as well as hepatic lipid concentrations and lipid-related gene expression were determined. Dietary sphingolipids dose-dependently lowered both plasma cholesterol and triacylglycerol in APOE*3Leiden mice; 1% phytosphingosine (PS) reduced plasma cholesterol and triacylglycerol by 57% and 58%, respectively. PS decreased the absorption of dietary cholesterol and free fatty acids by 50% and 40%, respectively, whereas intestinal triacylglycerol lipolysis was not affected. PS increased hepatic VLDL-triacylglycerol production by 20%, whereas plasma lipolysis was not affected. PS increased the hepatic uptake of VLDL remnants by 60%. Hepatic messenger RNA concentrations indicated enhanced hepatic lipid synthesis and VLDL and LDL uptake. The net result of these changes was a strong decrease in plasma cholesterol and triacylglycerol. The livers of 1% PS-fed mice were less pale, 22% lighter, and contained 61% less cholesteryl ester and 56% less triacylglycerol than livers of control mice. Furthermore, markers of liver inflammation (serum amyloid A) and liver damage (alanine aminotransferase) decreased by 74% and 79%, respectively, in PS-fed mice. Sphingolipids lower plasma cholesterol and triacylglycerol and protect the liver from fat- and cholesterol-induced steatosi