Weizheng Wang

Circulating Levels of IL-1β, a Prothrombotic Cytokine, are Elevated in Unstable Angina Versus Stable Angina

Background: Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. However, of the known proinflammatory cytokines, only elevated plasma levels of interleukin-6 have been linked to unstable angina. We sought to examine the plasma levels of other major proinflammatory cytokines in similar clinical settings and to determine the extent of the relationship between inflammation and unstable coronary syndromes by measuring the levels of various proinflammatory cytokines in patients with stable and unstable angina.Methods: We measured plasma levels of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) in 97 patients: 67 with stable angina, 24 with unstable angina, and 15 healthy controls.Results: Mean levels of IL-1β were significantly higher in patients with unstable angina as compared to patients with stable angina (p = .009). Levels of IL-6 were significantly higher than control patients for both stable angina and unstable angina patients (p = .031 and .006, respectively). No significant differences were found in the levels of TNF-α.Conclusions: Our results suggest that both IL-1β and IL-6 contribute to the pathogenesis of unstable angina, and that the profile of circulating plasma levels of proinflammatory cytokines differs in unstable angina from that in stable angina.Abbreviated Abstract. Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. We measured plasma levels of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) in patients with stable and unstable coronary syndromes. Levels of IL-1β and IL-6 were found to be elevated in patients with unstable coronary syndromes. No significant differences were found in the levels of TNF-α. Our results suggest that both IL-1β and IL-6 contribute to the pathogenesis of unstable angina.

Sequence-independent inhibition of in vitro vascular smooth muscle cell proliferation, migration, and in vivo neointimal formation by phosphorothioate oligodeoxynucleotides.

Phosphorothioate oligodeoxynucleotides (PS oligos) are antisense (sequence-specific) inhibitors of vascular smooth muscle cell (SMC) proliferation when targeted against different genes. Recently an aptameric G-quartet inhibitory effect of PS oligos has been demonstrated. To determine whether PS oligos manifest non-G-quartet, non-sequence-specific effects on human aortic SMC, we examined the effects of S-dC28, a 28-mer phosphorothioate cytidine homopolymer, on SMC proliferation induced by several SMC mitogens. S-dC28 significantly inhibited SMC proliferation induced by 10% FBS as well as the mitogens PDGF, bFGF, and EGF without cytotoxicity. Moreover, S-dC28 abrogated PDGF-induced in vitro migration in a modified micro-Boyden chamber. Furthermore, S-dC28 manifested in vivo antiproliferative effects in the rat carotid balloon injury model. S-dC28 suppressed neointimal cross-sectional area by 73% and the intima/media area ratio by 59%. Therefore, PS oligos exert potent non-G-quartet, non-sequence-specific effects on in vitro SMC proliferation and migration as well as in vivo neointimal formation.

Plasma Levels of Tissue Plasminogen Activator and Plasminogen Activator Inhibitor-1 Are Correlated With the Presence of Transplant Coronary Artery Disease in Cardiac Transplant Recipients

Hemostatic factors are involved in the pathogenesis of native coronary artery disease. However, their role in transplant coronary artery disease is less established. To assess the role of hemostatic factors in transplant coronary artery disease we studied 52 consecutive cardiac transplant patients. The presence of transplant coronary artery disease was determined by angiography. Plasma levels of tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), von Willebrand Factor (vWF), and fibrin D-dimer were determined by enzyme-linked immunosorbent assays. Serum lipids were measured by enzymatic methods. Patients with transplant coronary artery disease had higher circulating t-PA (8.6 +/- 0.8 vs. 5.4 +/- 0.6 ng/ml, p = 0.021) and PAI-1 antigen concentrations (38.0 +/- 3.4 vs 25.8 +/- 2.2 ng/ml, p = 0.037). t-PA and PAI-1 antigen concentrations correlated with the severity of angiographic disease (R = 0.34; p = 0.014 for t-PA, and R = 0.45; p = 0.001 for PAI-1). Serum cholesterol levels were higher in patients with transplant coronary artery disease (221 +/- 7.6 vs 191 +/- 9.2 mg/dl, p = 0.039). Serum triglycerides were also higher in patients with transplant coronary artery disease by angiography (246 +/- 38.3 vs 139 +/- 20.8 mg/dl, p = 0.050). Multivariate analysis identified t-PA antigen (p = 0.003) and triglyceride levels (p = 0.038) as independent predictors for the presence of transplant coronary artery disease. We conclude that cardiac transplant patients with evidence of transplant coronary artery disease on coronary angiography have altered hemostatic function which is reflected by elevated levels of circulating t-PA and PAI-1 antigens. The interaction of the hemostatic system and serum lipids in the development of transplant coronary artery disease warrants further study.

T-Cell Lymphokines, Interleukin-4 and Gamma Interferon, Modulate the Induction of Vascular Smooth Muscle Cell Tissue Plasminogen Activator and Migration by Serum and Platelet-Derived Growth Factor

Platelet-derived growth factor (PDGF)-induced smooth muscle cell (SMC) fibrinolysis is necessary for SMC migration. In order to determine whether the T-cell lymphokines interleukin-4 (IL-4) and gamma interferon (gamma-IFN) affect SMC fibrinolysis and migration, we examined the effects of human recombinant IL-4 and gamma-IFN on human aortic SMC tissue-type plasminogen activator (TPA), urokinase-type plasminogen activator (UPA), and plasminogen activator inhibitor type-1 (PAI-1) antigen production, as determined by enzyme-linked immunosorbent assays. Although IL-4 had no direct effect on SMC TPA antigen, IL-4 potentiated SMC TPA antigen levels and activity in conditioned media and cellular lysates in media containing 2% fetal bovine serum but did not change UPA or PAI-1 production. gamma-IFN attenuated IL-4 augmentation of SMC TPA antigen production in conditioned media, although gamma-IFN itself had no direct effects on SMC TPA and PAI-1 antigen production. IL-4 augmented PDGF induction of SMC TPA antigen. gamma-IFN inhibited PDGF induction of SMC TPA antigen and IL-4 potentiation of this process. gamma-IFN diminished the promigratory effects of both IL-4 and PDGF on in vitro SMC migration. Tranexamic acid, a plasmin inhibitor, abrogated the stimulation of SMC migration by IL-4. Therefore, IL-4 and gamma-IFN modulate the induction of SMC TPA and SMC migration by 2% fetal bovine serum and PDGF.

Interleukin-4 Modulation of Platelet-Derived Growth Factor–Induced Smooth Muscle Cell Urokinase Plasminogen Activator

Platelet-derived growth factor (PDGF) stimulates smooth muscle cell (SMC) migration owing to stimulation of SMC tissue plasminogen activator (t-PA) production. In this study we examined the effects of the T-cell lymphokine interleukin-4 (IL-4) on PDGF induction of human aortic SMC antigen levels of urokinase-type plasminogen activator (u-PA) and those of plasminogen activator inhibitor-1 (PAI-1), the endogenous inhibitor of t-PA and u-PA, measured by enzyme-linked immunosorbent assays (ELISAs). u-PA antigen levels from human aortic SMC incubated with PDGF 100 ng/mL and IL-4 500 U/mL were significantly greater than those incubated with PDGF 100 ng/mL alone. Coincubation of PDGF with IL-4 did not significantly increase SMC u-PA antigen levels in cellular lysates. Coincubation with PDGF 100 ng/mL and IL-4 500 U/mL did not significantly affect SMC PAI-1 antigen levels in conditioned media or cellular lysates. Therefore, interleukin-4 modulates vascular SMC u-PA production induced by PDGF.

Phosphorothioate Oligodeoxynucleotide Inhibition of Restenosis

Antisense therapy with phosphorothioate oligodeoxynucleotides (PS oligos) has emerged as a potentially useful strategy for inhibiting angioplasty restenosis. Several groups have reported that PS oligos inhibit in vitro vascular smooth muscle cell (SMC) proliferation as well as in vivo neointimal formation after rat carotid artery balloon injury. More recent studies have revealed the presence of a PS oligo G-quartet inhibitory effect, reflecting binding of oligonucleotides to cellular proteins, which is distinct from a hybridization-dependent antisense effect. Studies with the 28-mer phosphorothioate cytidine homopolymer S-dC28 have demonstrated the presence of a non–G-quartet, non–sequence-specific inhibitory effect on SMC proliferation and migration in vitro and neointimal hyperplasia after rat carotid balloon injury in vivo. These effects are the result, in part, of the avid binding of the polyanion PS oligos to heparin-binding growth factors, such as platelet-derived growth factor (PDGF) and basic fibroblast growth factor. Moreover, S-dC28 attenuates PDGF-induced SMC tissue plasminogen activator antigen levels without affecting SMC plasminogen activator inhibitor-1 levels, thereby suggesting a PS oligo net antifibrinolytic effect that would impede SMC migration. Therefore, the further development of these drugs to inhibit angioplasty restenosis must consider the hybridization-specific antisense effects, the non-G-quartet inhibitory effects, and the non–G-quartet, non–sequence-specific inhibitory effects of the pleiotropic PS oligos.

Non-G-Quartet, Non-Sequence Specific Antirestenotic Effects Of Phosphorothioate Oligodeoxynucleotides

Phosphorothioate oligodeoxynucleotides (PS ODNs) are isoelectronic congeners of phosphodiester oligonucleotides (1). These compounds are nuclease resistant, soluble in aqueous solution, and capable of engaging in Watson-Crick base pair hybridization (1). PS ODNs directed against various protooncogenes such as c-myb and c-myc involved in vascular smooth muscle cell (SMC) proliferation have been employed in sequence-specific antisense strategies to inhibit restenosis after balloon injury (2). Several studies have demonstrated that PS ODNs inhibit in vitro vascular SMC proliferation (3–8). In one study, there was sustained inhibition of SMC proliferation lasting several days after only a single two hour exposure to antisense nonmuscle myosin heavy chain and c-myb oligonucleotides (8). Furthermore, PS ODNs have inhibited restenosis after balloon injury in the rat carotid artery and porcine models (4,5,9).