Tranilast restores cytokine-induced nitric oxide production against platelet-derived growth factor in vascular smooth muscle cells

Effect of tranilast in comparison with beclomethasone in chronic murine model of asthma

AIM OF THE STUDY

The current investigation was taken to scrutinize the action of tranilast on the airway remodeling in chronic asthma in mice.

MATERIALS AND METHODS

Intraperitoneal injection of ovalbumin was applied to mice for sensitization and subsequent inhalation of 1% ovalbumin three times week for 10 weeks for challenge. Beclomethasone or tranilast were given daily for the 10 week challenge period. At the end of the study, lung weight index, total collagen content, bronchoalveolar lavage level of total and differential cell counts, interleukin-13, in addition to lung tissue nitrate/nitrite and transforming growth beta-1 were measured. Also, histological analysis was done.

RESULTS

Asthmatic mice demonstrated apparent fibrotic changes. Significant airway fibrosis was demonstrated by hyperplasia of goblet cells and thickening of airway epithelium, increased content of lung collagen, lung and bronchoalveolar lavage of transforming growth factor beta-1 and interleukin-13 mutually accompanied by reduction in nitrate/nitrite generation.

CONCLUSIONS

Beclomethasone influence on airway remodeling was mediated mainly via suppression of eosinophilic recruitment into the airways and reduction of interleukin-13 cytokine levels. Whereas, tranilast effects on airway remodeling was found to be mainly mediated via its inhibitory effect on transforming growth beta-1. Both beclomethasone and tranilast influence airway remodeling by different degrees and mechanisms.

Tranilast increases vasodilator response to acetylcholine in rat mesenteric resistance arteries through increased EDHF participation

Background and Purpose

Tranilast, in addition to its capacity to inhibit mast cell degranulation, has other biological effects, including inhibition of reactive oxygen species, cytokines, leukotrienes and prostaglandin release. In the current study, we analyzed whether tranilast could alter endothelial function in rat mesenteric resistance arteries (MRA).

Experimental Approach

Acetylcholine-induced relaxation was analyzed in MRA (untreated and 1-hour tranilast treatment) from 6 month-old Wistar rats. To assess the possible participation of endothelial nitric oxide or prostanoids, acetylcholine-induced relaxation was analyzed in the presence of L-NAME or indomethacin. The participation of endothelium-derived hyperpolarizing factor (EDHF) in acetylcholine-induced response was analyzed by preincubation with TRAM-34 plus apamin or by precontraction with a high K⁺ solution. Nitric oxide (NO) and superoxide anion levels were measured, as well as vasomotor responses to NO donor DEA-NO and to large conductance calcium-activated potassium channel opener NS1619.

Key Results

Acetylcholine-induced relaxation was greater in tranilast-incubated MRA. Acetylcholine-induced vasodilation was decreased by L-NAME in a similar manner in both experimental groups. Indomethacin did not modify vasodilation. Preincubation with a high K⁺ solution or TRAM-34 plus apamin reduced the vasodilation to ACh more markedly in tranilast-incubated segments. NO and superoxide anion production, and vasodilator responses to DEA-NO or NS1619 remained unmodified in the presence of tranilast.

Conclusions and Implications

Tranilast increased the endothelium-dependent relaxation to acetylcholine in rat MRA. This effect is independent of the nitric oxide and cyclooxygenase pathways but involves EDHF, and is mediated by an increased role of small conductance calcium-activated K+ channels.

Evaluation of neointimal hyperplasia on tranilast-coated synthetic vascular grafts: an experimental study

Tranilast is an antiallergic drug that interferes with proliferation and migration of vascular smooth muscle cell induced by platelet-derived growth factor (PDGF) and transforming growth factor-beta1 (TGF-beta1). We investigated the local effect of tranilast on neointimal hyperplasia using tranilast-coated prosthetic grafts. The inner sides of the thin-walled polytetrafluoroethylene (PTFE) grafts were coated with chitosan and tranilast containing chitosan solution. Wistar albino rats (32) were used in the study. Patches (1 x 2 mm) for vascular grafts were prepared. Three groups were tested: group 1 (n = 12; tranilast coated), group 2 (n = 10; adhesive-only film-layer-coated), and group 3 (n = 10; normal ePTFE patch grafts sutured to the carotid arteries of the rats). Recipient sites of the carotid arteries were excised 4 weeks after surgery. All sections were examined histologically for graft patency, thrombus formation, and neointimal thickness. Expression of PDGF, fibroblast growth factor, and TGF-beta1 on cross-sections of the neointima were evaluated by immunohistochemistry. No significant differences were found regarding mean neointimal thicknesses. PDGF and TGF-beta-1 expressions were significantly lower in group 1. Although a decrease in local effect of tranilast was observed for growth factor expressions at a drug concentration of 0.05 mg/cm(2), a significant reduction in neointimal hyperplasia was not achieved. The coating concentration of 0.05 mg/cm(2) may have been too low to produce an antiproliferative effect. Given our promising results, further studies are recommended and planned using different drug concentrations and time intervals.

Biodegradable stents as a platform to drug loading

Despite technical and mechanical improvement in coronary stents the incidence of restenosis caused by in-stent neointimal hyperplasia remains high. Oral administration of numerous pharmacological agents has failed to reduce restenosis after coronary stenting in humans, possibly owing to insufficient local drug concentration. Therefore, drug-eluting stents were developed as a vehicle for local drug administration. The authors developed a new drug-eluting polymer stent that is made of poly-l-lactic acid polymer mixed with tranilast, an anti-allergic drug that inhibits the migration and proliferation of vascular smooth muscle cells induced by platelet-derived growth factor and transforming growth factor->1. Polymer stents might be superior to polymer-coated metallic stents as local drug delivery stents in terms of biodegradation and the amount of loaded drug. Drug-mixed polymer stents can be loaded with a larger amount of drug than can drug-coated metallic stents because the polymer stent struts can contain the drug. Clinical application is required to assess the safety and efficacy of drug-eluting polymer stents against stent restenosis.

Effect of Perilla frutescens on nitric oxide production and DNA synthesis in cultured murine vascular smooth muscle cells

The effects of perilla (Perilla frutescens, Labiatae) on murine cultured vascular smooth muscle cells (VSMC) were investigated. The water extract of perilla leaves induced nitric oxide (NO) production of VSMC and this effect was synergistically augmented when combined with interferon (IFN)-gamma or tumour necrosis factor (TNF)-alpha, while the perilla extract significantly inhibited NO production induced by IFN-gamma combined with lipopolysaccharide (LPS). Northern blot analysis revealed that these effects of the perilla extract paralleled mRNA expression of inducible nitric oxide synthase. However, the perilla extract significantly inhibited platelet derived growth factor (PDGF) or TNF-alpha-induced VSMC proliferation measured as DNA synthesis. The inhibitory effect of the perilla extract on TNF-alpha-induced VSMC proliferation was significantly suppressed by N(G)-monomethyl-L-arginine, a non-specific nitric synthase inhibitor, suggesting that this effect was partially mediated by NO production as an autocrine/paracrine factor. The present findings suggest that perilla would be useful for the prevention of vascular diseases such as arteriosclerosis.

N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast) suppresses microglial inducible nitric oxide synthase (iNOS) expression and activity induced by interferon-gamma (IFN-gamma)

1. Microglial cells up-regulate inducible nitric oxide synthase (iNOS) expression in response to various pro-inflammatory stimuli including interferon-gamma (IFN-gamma), allowing for the release of nitric oxide (NO). Tranilast (N-[3,4-dimethoxycinnamoyl]-anthranilic acid) is an antiallergic compound with suppressive effects on the activation of monocytes. 2. Here, we show that N9 murine microglial cells express iNOS mRNA and protein and release nitric oxide into the culture medium in response to IFN-gamma (200 u x ml(-1)) as measured by Northern and Western blot analyses and Griess assay. 3. Exposure to non-toxic doses of tranilast (30-300 microM) leads to a concentration-dependent inhibition of IFN-gamma-induced (200 u x ml(-1)) iNOS mRNA and protein expression. This is paralleled by a suppression of NO-release into the cell culture medium. 4. Inhibition of IFN-gamma-induced iNOS mRNA expression by tranilast is paralleled by an inhibition of nuclear factor-kappaB (NF-kappaB) activation and phosphorylation of inhibitory kappaB (IkappaB) as determined by Western blot analyses and NF-kappaB reporter gene assay. 5. These results suggest that tranilast-mediated suppression of microglial iNOS activity induced by IFN-gamma involves the inhibition of NF-kappaB-dependent iNOS mRNA expression.

Tranilast inhibits interleukin-1beta-induced monocyte chemoattractant protein-1 expression in rat mesangial cells

Monocyte chemoattractant protein-1 (MCP-1), a member of the CC subfamily of chemokines, plays a crucial role in the progression of glomerulonephritis by recruitment of monocytes. Tranilast, a clinically used anti-allergic drug, has been demonstrated to have various anti-inflammatory and anti-proliferative effects, and recently has been reported to prevent restenosis after percutaneous transluminal coronary angioplasty. In this study, we investigated whether tranilast inhibits MCP-1 secretion in mesangial cells. Tranilast inhibited interleukin-1beta-induced MCP-1 secretion and mRNA expression in a concentration-dependent manner. Luciferase assay showed that tranilast suppressed interleukin-1beta-induced nuclear factor-kappaB (NF-kappaB)-dependent transcription. Interleukin-1beta-induced Jun N-terminal kinase (JNK) activation was also suppressed selectively by tranilast. These results indicate that tranilast inhibits interleukin-1beta-induced MCP-1 production, at least in part, by inhibiting NF-kappaB activity and that suppression of JNK activation might be involved in the inhibition of MCP-1 production. Tranilast may serve as a new therapeutic agent for glomerulonephritis through anti-chemokine property.

Apoptosis in atherosclerosis: pathological and pharmacological implications

Normal embryonic development, tissue differentiation and repair in the eukaryote requires a tightly regulated apoptosis, or programmed cell death. Apoptosis also plays an essential role in different pathological processes including atherosclerosis, in which it affects all cell types in the atherosclerotic lesion, including endothelial cells, vascular smooth muscle cells, and macrophages. During atherosclerosis progression, pro- and anti-apoptotic signals abound in the evolving lesion. Apoptosis limits the number of a particular cell type that accumulates in the lesion and slows down the overall progression of the lesion. On the other hand, it contributes to the production of unstable plaques. Many pharmacological agents used to treat cardiovascular and lipid disorders have pro- or/and anti-apoptotic effects. Pharmaceuticals that modulate apoptosis in specific types of cell can potentially serve as anti-atherogenic agents. However, to develop agents for clinical use requires a thorough knowledge of the pathophysiology of apoptosis in atheromatous lesions, a highly cell-specific process. Here we review our current understanding of the process to provide a background for future pharmacological research in the area.

Nitric oxide and postangioplasty restenosis: pathological correlates and therapeutic potential

Balloon angioplasty revolutionized interventional cardiology as a nonsurgical procedure to clear a diseased artery of atherosclerotic blockage. Despite its procedural reliability, angioplasty's long-term outcome can be compromised by restenosis, the recurrence of arterial blockage in response to balloon-induced vascular trauma. Restenosis constitutes an important unmet medical need whose pathogenesis has yet to be understood fully and remains to be solved therapeutically. The radical biomediator, nitric oxide (NO), is a natural modulator of several processes contributing to postangioplasty restenosis. An arterial NO deficiency has been implicated in the establishment and progression of restenosis. Efforts to address the restenosis problem have included trials evaluating a wide range of NO-based interventions for their potential to inhibit balloon-induced arterial occlusion. All types of NO-based interventions yet investigated benefit at least one aspect of balloon injury to a naive vessel in a laboratory animal without inducing significant side effects. The extent to which this positive, albeit largely descriptive, body of experimental data can be translated into the clinic remains to be determined. Further insight into the pathogenesis of restenosis and the molecular mechanisms by which NO regulates vascular homeostasis would help bridge this gap. At present, NO supplementation represents a unique and potentially powerful approach to help control restenosis, either alone or as a pharmaceutical adjunct to a vascular device.

Inhibitory mechanism of tranilast in human coronary artery smooth muscle cells proliferation, due to blockade of PDGF-BB-receptors

We have previously reported that tranilast, an anti-allergic drug, prevented the experimental intimal thickening in the rat and mouse femoral arteries and its effect may be exerted through the inhibition of vascular smooth muscle cell proliferation. However, its inhibitory mechanism has yet to be understood. In this study, we investigated the inhibitory effect of tranilast on platelet-derived growth factor BB-homodimer (PDGF-BB) mediated signal transduction pathways in cultured human coronary artery smooth muscle cells (CASMCs). Growth responses to PDGF-BB were measured by [(3)H]-thymidine incorporation or cell counting. Activation of DNA synthesis and augmentation of cell proliferation stimulated by PDGF-BB in quiescent cultures of CASMCs were inhibited by tranilast in a concentration-dependent manner. Western blot analysis of lysates from CASMCs with an anti-activated mitogen-activated protein (MAP) kinase antibody revealed that tranilast (10 - 300 microM) inhibited MAP kinase activation by PDGF-BB in a concentration-dependent manner. Tranilast also reduced PDGF-BB-stimulated tyrosine phosphorylation of a 180 kDa band, corresponding in mass to the PDGF beta-receptor, as shown by immunoblots using an anti-phosphotyrosine antibody. Receptor-binding study with [(125)I]-PDGF-BB on CASMCs showed that tranilast (10 - 1000 microM) inhibited the specific binding of PDGF-BB to cell surface receptors in a concentration-dependent manner. Scatchard analysis revealed that pretreatment with 300 microM tranilast decreased the maximum binding capacity (B(max)) from 27.6 to 18.0 fmol 10(6) cells(-1) without affecting binding affinity (K(d) approximately 0.15 nM), indicating a non-competitive inhibition of the receptor binding. These results suggest that the suppression of human CASMC growth by tranilast might be at least partly due to blockade of PDGF-BB-receptor binding.

Inhibition of neointima formation by tranilast in pig coronary arteries after balloon angioplasty and stent implantation

OBJECTIVES

We evaluated the effect of orally administered tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, on histologic and histomorphometric changes after angioplasty or stent implantation in pig coronary arteries.

BACKGROUND

Tranilast, which has antikeloid and antiallergic properties and therefore may modulate the fibrotic and inflammatory tissue responses to angioplasty and stenting, has been shown to inhibit angiographic restenosis in small clinical trials. However, its effect on histomorphometric changes in coronary arteries after angioplasty and stenting is unknown.

METHODS

Following initial pharmacokinetic studies in two pigs to determine desirable plasma levels of orally administered tranilast, 36 crossbred juvenile pigs were randomized to placebo or tranilast before undergoing balloon angioplasty in both the left anterior descending and left circumflex plus stent implantation in the right coronary artery. Oral tranilast was administered at 3 g/day starting 3 days before coronary injury and continued for 28 days until euthanasia. Injured vessels were harvested and sections analyzed by computer-assisted microscopic planimetry.

RESULTS

In balloon-injured vessels, tranilast was associated with a 37% reduction in neointimal area normalized to fracture length (0.47 +/- 0.01 vs. 0.74 +/- 0.03 mm; p < 0.001) and a 23% reduction in adventitial area normalized to vessel size (0.43 +/- 0.02 vs. 0.56 +/- 0.03; p = 0.003). In stented arteries, neointimal area normalized to injury score was 32% lower in the tranilast-treated group compared to control (1.94 +/- 0.17 vs. 2.86 +/- 0.29; p = 0.01).

CONCLUSIONS

In pig coronary arteries, tranilast was associated with a reduction in neointima formation and adventitial reaction after balloon injury. In stented vessels, tranilast was associated with a reduction in neointima formation normalized to injury score.

The PRESTO (Prevention of restenosis with tranilast and its outcomes) protocol: a double-blind, placebo-controlled trial

BACKGROUND

Tranilast is a unique drug in clinical development for the prevention of restenosis after percutaneous transluminal coronary revascularization (PTCR). Tranilast interferes with proliferation and migration of vascular medial smooth muscle cells induced by platelet-derived growth factor and transforming growth factor beta1. Collagen synthesis in vascular medial smooth muscle cells is inhibited by tranilast, which also inhibits the release or production of cyclooxygenase-2 and restores cytokine-induced nitric oxide production. These mechanisms may contribute to the reduction of angiographic restenosis after coronary intervention previously reported in clinical studies.

METHODS

The primary objective of this multicenter study of 11,500 patients is to compare the composite clinical event rate of death, myocardial infarction, or the need for ischemia-driven target vessel revascularization of tranilast (300 and 450 mg twice daily) for 1 or 3 months with that of placebo in patients undergoing PTCR with or without stenting for single or multiple vessels over a 9-month period. The lesions can be de novo or restenotic. All revascularization procedures and the use of glycoprotein IIb/IIIa agents are permitted. The inclusion criteria are meant to allow an "all comer" approach for generalization of results to the broadest possible PTCR population. A subset population (n = 2000) will undergo 9-month follow-up angiography, 1000 of which will also undergo intravascular ultrasound (n = 1000). This study is the first tranilast trial to be conducted in a Western population to confirm the improved angiographic findings reported in Japanese patients and to determine if the clinical sequelae of restenosis are also reduced.

CONCLUSION

This multicenter study is the largest restenosis trial planned to date. It will test whether tranilast, a drug with multiple actions aimed at affecting proliferation and migration of vascular smooth muscle cells, can reduce clinical, angiographic, and intravascular ultrasound assessments of restenosis.

Impact of tranilast on restenosis after coronary angioplasty: tranilast restenosis following angioplasty trial (TREAT)

BACKGROUND

Tranilast is an antiallergic drug that suppresses the release of cytokines such as platelet-derived growth factor, transforming growth factor-beta1, and interleukin-1beta and prevents keloid formation after skin injury. Treatment with this drug reduced the restenosis rate after percutaneous transluminal coronary angioplasty in a preliminary study.

METHODS AND RESULTS

We conducted a multicenter, randomized, double-blind, placebo-controlled trial. A total of 255 patients with 289 lesions were randomly assigned to treatment with the oral administration of 600 mg/d tranilast, 300 mg/d tranilast, or a placebo for 3 months after successful angioplasty. Angiographic follow-up was done at 3 months, and a clinical follow-up examination was performed at 12 months. Two hundred ten (72.7%) lesions of 188 (73.7%) of the patients met the criteria and were eligible for the assessment of restenosis. The restenosis rates defined as >/=50% loss of the initial gain were 14.7% in the 600 mg/d tranilast group, 35.2% in the 300 mg/d tranilast group, and 46.5% in the placebo group (P <. 0001 for 600 mg/d tranilast vs placebo). The restenosis rates defined as percent diameter stenosis of >/=50% at follow-up were 17. 6% in the 600 mg/d tranilast group, 38.6% in the 300 mg/d tranilast group, and 39.4% in the placebo group (P =.005 for 600 mg/d tranilast vs placebo).

CONCLUSIONS

The oral administration of 600 mg/d of tranilast for 3 months markedly reduced the restenosis rate after percutaneous transluminal coronary angioplasty.

Tranilast inhibits protein kinase C-dependent signalling pathway linked to angiogenic activities and gene expression of retinal microcapillary endothelial cells

1. Tranilast, first developed as an anti-allergic drug, has been reported to inhibit vascular endothelial growth factor (VEGF)-induced angiogenesis and vasopermeability. To further clarify the inhibitory mechanism, we investigated the effects of tranilast on VEGF binding and subsequent intracellular signalling pathway linked to angiogenic activities and gene expression of bovine retinal microcapillary endothelial cells. 2. Tranilast significantly (P<0.01) inhibited VEGF, basic fibroblast growth factor (bFGF), and hypoxia conditioned media-induced BREC proliferation in a dose dependent manner with IC50's of 22, 82 and 10 microM, respectively. 3. VEGF-induced migration was also inhibited by tranilast in a dose dependent manner, with IC50 of 18 microM, and complete inhibition was observed at 300 microM (P<0.01). Tranilast suppressed VEGF-induced tube formation in a dose dependent manner with maximum (46%) inhibition observed at 300 microM (P<0.05). 4. Tranilast inhibited phorbol myristate acetate (PMA)-dependent stimulation of [3H]-thymidine incorporation and VEGF- and PMA-induced gene expression of integrin alpha v and c-fos in BREC. 5. Tranilast suppressed VEGF- and PMA-stimulated PKC activity in BREC. 6. Tranilast did not affect VEGF binding or VEGF-induced phosphorylation of tyrosine residues of VEGF receptor- and phospholipase Cgamma and their associated proteins. 7. These data suggest that tranilast might prove an effective inhibitor to prevent retinal neovascularization in ischaemic retinal diseases, and that its inhibitory effect might be through suppression of PKC-dependent signal transduction in BREC.

Felodipine inhibits free-radical production by cytokines and glucose in human smooth muscle cells

An imbalance between nitric oxide (NO) and superoxide is importantly involved in the pathogenesis of vascular disease. Inflammatory stimuli and risk factors contribute to these alterations. Calcium antagonists and angiotensin-converting enzyme inhibitors are commonly used cardiovascular drugs. To clarify the effect of felodipine and ramiprilat on the balance of these free radicals, we stimulated human aortic smooth muscle cells (HASCs) with cytokines (human interleukin-1beta, tumor necrosis factor-alpha, lipopolysaccharide, and/or interferon-gamma) or high glucose in the presence and absence of these compounds. Felodipine, but not ramiprilat, concentration-dependently inhibited cytokine-induced NO production and NO synthase (NOS) mRNA induction. The antioxidant N-acetylcysteine also inhibited cytokine-induced NO production and induction of inducible NOS mRNA. Moreover, felodipine inhibited cytokine-induced superoxide production both in the presence and absence of an NOS inhibitor, suggesting that it acted as a superoxide scavenger and not as an inhibitor of inducible NOS induction. High glucose treatment (22 mmol/L for 48 hours) also significantly increased superoxide production in HASCs, and this increase was inhibited in a concentration-dependent manner by felodipine but not by ramiprilat. These results suggest that felodipine may exert vascular protective effects by suppressing free radical generation in human smooth muscle cells during activation of inflammatory mechanisms and diabetic conditions.