Inhibition of type-1 plasminogen activator inhibitor production by antisense oligonucleotides in human vascular endothelial and smooth muscle cells

Plasminogen activator inhibitor-1 antisense oligodeoxynucleotides abrogate mesangial fibronectin accumulation

Excessive extracellular matrix (ECM) accumulation is the main feature of chronic renal disease including diabetic nephropathy. Plasminogen activator inhibitor (PAI)-1 is known to play an important role in renal ECM accumulation in part through suppression of plasmin generation and matrix metalloproteinase (MMP) activation. The present study examined the effect of PAI-1 antisense oligodeoxynucleotide (ODN) on fibronectin upregulation and plasmin/MMP suppression in primary mesangial cells cultured under high glucose (HG) or transforming growth factor (TGF)-β1, major mediators of diabetic renal ECM accumulation. Growth arrested and synchronized rat primary mesangial cells were transfected with 1 µM phosphorothioate-modified antisense or control mis-match ODN for 24 hours with cationic liposome and then stimulated with 30 mM D-glucose or 2 ng/ml TGF-β1. PAI-1 or fibronectin protein was measured by Western blot analysis. Plasmin activity was determined using a synthetic fluorometric plasmin substrate and MMP-2 activity analyzed using zymography. HG and TGF-β1 significantly increased PAI-1 and fibronectin protein expression as well as decreased plasmin and MMP-2 activity. Transient transfection of mesangial cells with PAI-1 antisense ODN, but not mis-match ODN, effectively reversed basal as well as HG- and TGF-β1-induced suppression of plasmin and MMP-2 activity. Both basal and upregulated fibronectin secretion were also inhibited by PAI-1 antisense ODN. These data confirm that PAI-1 plays an important role in ECM accumulation in diabetic mesangium through suppression of protease activity and suggest that PAI-1 antisense ODN would be an effective therapeutic strategy for prevention of renal fibrosis including diabetic nephropathy.

The status of plasminogen activator inhibitor-1 as a therapeutic target

Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of tissue-type plasminogen activator (tPA). An increase in the plasma concentration of PAI-1 has been proposed as a risk factor in thrombotic disease and elevated PAI-1 is associated with a poor prognosis in a variety of cancers. These observations have led to numerous studies addressing the physiological and pathophysiological role of PAI-1 and to the proposal that manipulation of PAI-1 activity presents a new therapeutic target. Recent experimental studies with anti-PAI-1 antibodies and low molecular weight inhibitors have demonstrated efficacy in both arterial and venous thrombosis models. These studies have confirmed the potential clinical benefit of reducing PAI-1 activity. As it is now possible to manipulate PAI-1 activity in vivo, future studies should be aimed at confirming the importance of PAI-1 as a major therapeutic target.

Novel inhibitors of plasminogen activator inhibitor-1: development of new templates from diketopiperazines

Several isoquinoline-based templates were identified from the studies of the conformational effects of the diketopiperazine structures for PAI-1 inhibition. Moderate to good activity was retained with the elimination of unattractive characteristics in the diketopiperazine template.

Plasminogen activator inhibitor type 1 is a potential target in renal fibrogenesis

Plasminogen activator inhibitor type 1 is a potential target in renal fibrogenesis. The progression of renal lesions to fibrosis involves several mechanisms, among which the inhibition of extracellular matrix (ECM) degradation appears to play an important role. Two interrelated proteolytic systems are involved in matrix degradation: the plasminogen activation system and the matrix metalloproteinase system. The plasminogen activator inhibitor type 1 (PAI-1), as the main inhibitor of plasminogen activation, regulates fibrinolysis and the plasmin-mediated matrix metalloproteinase activation. PAI-1 is also a component of the ECM, where it binds to vitronectin. PAI-1 is not expressed in the normal human kidney but is strongly induced in various forms of kidney diseases, leading to renal fibrosis and terminal renal failure. Thrombin, angiotensin II, and transforming growth factor-beta are potent in vitro and in vivo agonists in increasing PAI-1 synthesis. Several experimental and clinical studies support a role for PAI-1 in the renal fibrogenic process occurring in chronic glomerulonephritis, diabetic nephropathy, focal segmental glomerulosclerosis, and other fibrotic renal diseases. Experimental models of renal diseases in PAI-1-deficient animals are in progress, and preliminary results indicate a role for PAI-1 in renal fibrogenesis. Inhibition of PAI-1 activity or of PAI-1 synthesis by specific antibodies, peptidic antagonists, antisense oligonucleotides, or decoy oligonucleotides has been obtained in vitro, but needs to be evaluated in vivo for the prevention or the treatment of renal fibrosis.

Plasminogen Activator Inhibitor 1: Molecular Aspects and Clinical Importance

Plasminogen activator inhibitor-1 (PAI-1) is the major physiologic inhibitor of plasminogen activation in plasma and in the blood vessel wall. PAI-1 exhibits distinctive structural and functional properties that have been extensively studied over the past decade. Aside from the physiological role of PAI-1, there is accumulating evidence that increased production of PAI-1 may contribute to the development of ischemic cardiovascular disease. Efforts are now underway to develop and test specific inhibitors of PAI-1.

Localization of 2 11beta-OH steroid dehydrogenase isoforms in aortic endothelial cells

11Beta-hydroxysteroid dehydrogenase (11beta-HSD) is expressed in vascular smooth muscle cells (VSMC) but has not been reported to be present in vascular endothelial cells. This enzyme assists in regulating the cellular concentration of active endogenous glucocorticoids (GCs). We have observed that endothelium intact rat aortic rings express message for both Type 1 and Type 2 11beta-HSD whereas primary cultures of VSMC express only mRNA for the Type I isoform. Since GCs diminish prostacyclin synthesis in endothelial cells, we hypothesized that 11beta-HSD is present in vascular endothelial cells. In primary cultures of rat aortic endothelial (RAE) cells, mRNA from both isoforms of 11beta-HSD could be detected by RT-PCR with higher levels of the Type 1 isoform. The oxo-reductase reaction "activating" 11-dehydro metabolites back to the parent steroid is the preferred enzyme direction (12:1 after a 120 minutes steroid incubation) in intact RAE cells. When RAE cells are grown in the presence of antisense oligonucleotides specific for Type 1 11beta-HSD, oxo-reductase activity is decreased by approximately 50% but the dehydrogenase reaction, which inactivates endogenous GCs and is characteristic of the Type 2 isoform, is unaffected. Thus endothelial cells appear to express both isoforms of 11beta-HSD; the Type 1 isoform dominates functioning in the oxo-reductase mode. Inhibition of the oxo-reductase reaction may lower the local concentrations of GC and indirectly allow for increased production of prostacyclin in endothelial cells.

Stereodependent inhibition of plasminogen activator inhibitor type 1 by phosphorothioate oligonucleotides: proof of sequence specificity in cell culture and in vivo rat experiments

Hexadecadeoxyribonucleotides complementary to a fragment of human PAI-1 mRNA located upstream of the start codon and their phosphorothioate analogs were studied in cultured HUVECs as sequence-dependent inhibitors of PAI-1 expression. The activity of the random mixture of diastereomers of phosphorothioate hexadecanucleotide PS-16H has been compared with that of isosequential, stereoregular [All-Sp] and [All-Rp] isomers. The highest inhibitory effect on PAI-1 synthesis was observed with the [All-Sp] diastereomer. Stereorandom phosphorothioate oligonucleotide PS-16R complementary to the same region of rat PAI-1 mRNA, when injected into tail vein of rats, substantially decreased the level of PAI-1 in blood plasma.

Advanced glycation end product (AGE)-mediated induction of tissue factor in cultured endothelial cells is dependent on RAGE

BACKGROUND

Binding of advanced glycation end products (AGEs) to the cellular surface receptor (RAGE) induces translocation of the transcription factor NF-kappaB into the nucleus and NF-kappaB-mediated gene expression. This study examines the role of RAGE in the AGE albumin-mediated induction of endothelial tissue factor, known to be partly controlled by NF-kappaB.

METHODS AND RESULTS

Endothelial cells (ECs) were incubated in the presence of an 18-mer phosphorothioate oligodeoxynucleotide antisense to the 5'-coding sequence of the RAGE gene (antisense RAGE; 0.1 micromol/L). Sense oligonucleotides (sense RAGE, 0.1 micromol/L) of the same region served as control. The cellular uptake of oligonucleotides was controlled by immunofluorescence microscopy. RAGE transcription was suppressed by antisense RAGE, as demonstrated by RT-PCR reactions. AGE albumin-mediated activation of cultured ECs was studied after 48 hours of preincubation of ECs with antisense or sense RAGE. Electrophoretic mobility shift assays and Western blot analysis demonstrated that the AGE albumin-induced translocation of NF-kappaB from the cytoplasm into the nucleus was suppressed in the presence of antisense RAGE but not by sense RAGE. In parallel, AGE albumin-mediated tissue factor transcription, activity, and antigen were significantly reduced in ECs exposed to antisense RAGE, whereas sense RAGE (and nonspecific oligonucleotides) did not influence tissue factor expression.

CONCLUSIONS

Activation of ECs and induction of tissue factor by AGE albumin in ECs is dependent on RAGE.

Modulation of plasminogen activator inhibitor type-1 biosynthesis in vitro and in vivo with oligo(nucleoside phosphorothioate)s and related constructs

Oligonucleotides with a nucleotide sequence complementary to various regions of human plasminogen activator inhibitor type-1 (PAI-1) mRNA have been studied as antisense inhibitors of expression of PAI-1 protein in cultured cells [human umbilical vein endothelial cells (HUVEC), human aortic smooth muscle cells, human hybrid endothelial cells]. Hexadeca(deoxyribonucleoside phosphorothioate) 13 complementary to a fragment of a signal peptide PAI-1 mRNA was found to be most active, giving ca. 70% inhibition of PAI-1 release in a time- and dose-dependent way. The stereo-regular All-S(P) and All-R(P) diastereomers of 13 were studied and found to inhibit PAI-1 synthesis in HUVEC in a stereo-dependent manner, with the All-S(P) diastereomer considerably more active than the stereo-random construct and All-R(P) isomer. The observed stereo-dependent activity of oligonucleotide phosphorothioate constructs is presumably governed by their resistance to nucleases. The corresponding phosphodiester analogue of 13 was not active unless covalently bound at its 5'-end to a lipophilic alcohol residue (menthol, heptadecanol). The observed antisense activity of phosphodiester oligonucleotide bioconjugates in cultured human hybrid endothelial cells was paralleled by their increased stability in human plasma with respect to unconjugated oligonucleotide. The oligo(deoxyribonucleoside phosphorothioate) complementary to the same signal peptide region of rat PAI-1 mRNA was found to reduce the PAI-1 level in blood plasma of rats after intravenous administration into the tail vein. The effect was both time- and dose-dependent. The same oligonucleotide was found to protect against arterial thrombus formation in the rat (lower incidence of venous thrombosis, lower thrombus weight, and increased occlusion time in experimentally induced thrombosis). An anti-PAI-1 inhibitory activity has been independently reported for a 20-mer oligo(2'-O-methyl-ribonucleoside phosphorothioate) complementary to a 3'-untranslated region of human PAI-1 mRNA in cultured HUVEC and human aortic smooth muscle cells.

A new butadiene derivative, T-686, inhibits plasminogen activator inhibitor type-1 production in vitro by cultured human vascular endothelial cells and development of atherosclerotic lesions in vivo in rabbits

Plasminogen activator inhibitor-1 (PAI-1), the major physiologic inhibitor of tissue-type plasminogen activator and urokinase, is abundantly expressed in atherosclerotic vascular wall. To determine the role of PAI-1 in vascular wall, we have used a novel inhibitor of PAI-1, (3E, 4E)-3-benzylidene-4-(3,4,5-trimethoxy-benzylidene) -pyrrolidine-2,5-dione (T-686). T-686 was given to human vascular endothelial cells in vitro and to rabbits subjected to high cholesterol diet and mechanical injury in vivo. T-686 attenuated the augmentation of PAI-1 antigen accumulation induced by transforming growth factor beta in conditioned medium from the human umbilical vein endothelial cells. In rabbits with aortic atherosclerosis induced by hypercholesterolemia and implantation of indwelling plastic tubing, oral administration of T-686 (30mg/kg body weight/day) for 8 weeks attenuated the increase in plasma PAI-1 activity induced by vascular injury without decreasing blood triglyceride and cholesterol. This was accompanied by the reduction in aortic PAI-1 mRNA expression and the inhibition of development of atherosclerosis lesions. Thus, T-686 not only decreased PAI-1 synthesis in vascular cells in vitro but also protected against the development of vascular lesions in vivo. This compound may be useful in defining the role of PAI-1 in atherothrombotic states.

Inhibition by modified oligodeoxynucleotides of the expression of type-1 plasminogen activator inhibitor in human endothelial cells

Antisense phosphodiester and phosphorothioate oligodeoxynucleotides (23-residue or 24-residue oligodeoxynucleotides) were constructed for sequences of type-1 plasminogen-activator-inhibitor mRNA to assess their capability to modulate type-1 plasminogen-activator-inhibitor-mediated fibrinolysis. Antisense oligodeoxynucleotides were targeted at the mRNA sequence coding a signal peptide, at a part of the reactive center Ile342-Pro349, and at an internally translated segment Asn265-Leu272. The effect of antisense oligonucleotides on the concentration of type-1 plasminogen activator inhibitor in conditioned media and human endothelial cells was determined by the activity test with fibrin as a substrate, and by immunoprecipitation after metabolic labelling of cells with [35S]methionine. Three phosphorothioate oligodeoxynucleotides were specifically inhibitory while phosphodiester oligodeoxynucleotides with the same sequence did not show any activity. Phosphorothioate oligodeoxynucleotides 2, 4 and 6 inhibited the synthesis of type-1 plasminogen activator inhibitor in endothelial cells in a time-dependent and concentration-dependent manner. These data suggest that antisense oligodeoxynucleotides may be useful in the design of antithrombolytic therapeutics.