Effectiveness of tranilast on restenosis after directional coronary atherectomy

Tranilast: a review of its therapeutic applications

Tranilast (N-[3',4'-dimethoxycinnamoyl]-anthranilic acid) is an analog of a tryptophan metabolite. Initially, tranilast was identified as an anti-allergic agent, and used in the treatment of inflammatory diseases, such as bronchial asthma, atypical dermatitis, allergic conjunctivitis, keloids and hypertrophic scars. Subsequently, the results showed that it could be also effective in the management of a wide range of conditions. The beneficial effects of tranilast have also been seen in a variety of disease states, such as fibrosis, proliferative disorders, cancer, cardiovascular problems, autoimmune disorders, ocular diseases, diabetes and renal diseases. Moreover, several trials have shown that it has very low adverse effects and it is generally well tolerated by patients. In this review, we have attempted to accurately summarize previously published studies relating to the use of tranilast for a range of disorders and discuss the drug's possible mode of action. The major mode of the drug's efficacy appears to be the suppression of the expression and/or action of the TGF-β pathway, but the drug affects other factors as well. The findings presented in this review demonstrate the potential of tranilast for the control of a vast array of pathological situations, furthermore, it is a prescribed drug without severe side effects.

Inhibition of the tumor necrosis factor-alpha pathway is radioprotective for the lung

PURPOSE

Radiation-induced lung toxicity limits the delivery of high-dose radiation to thoracic tumors. Here, we investigated the potential of inhibiting the tumor necrosis factor-alpha (TNF-alpha) pathway as a novel radioprotection strategy.

EXPERIMENTAL DESIGN

Mouse lungs were irradiated with various doses and assessed at varying times for TNF-alpha production. Lung toxicity was measured by apoptosis and pulmonary function testing. TNF receptor 1 (TNFR1) inhibition, achieved by genetic knockout or antisense oligonucleotide (ASO) silencing, was tested for selective lung protection in a mouse lung metastasis model of colon cancer.

RESULTS

Lung radiation induced local production of TNF-alpha by macrophages in BALB/c mice 3 to 24 hours after radiation (15 Gy). A similar maximal induction was found 1 week after the start of radiation when 15 Gy was divided into five daily fractions. Cell apoptosis in the lung, measured by terminal deoxyribonucleotide transferase-mediated nick-end labeling staining (mostly epithelial cells) and Western blot for caspase-3, was induced by radiation in a dose- and time-dependent manner. Specific ASO inhibited lung TNFR1 expression and reduced radiation-induced apoptosis. Radiation decreased lung function in BALB/c and C57BL mice 4 to 8 weeks after completion of fractionated radiation (40 Gy). Inhibition of TNFR1 by genetic deficiency (C57BL mice) or therapeutic silencing with ASO (BALB/c mice) tended to preserve lung function without compromising lung tumor sensitivity to radiation.

CONCLUSION

Radiation-induced lung TNF-alpha production correlates with early cell apoptosis and latent lung function damage. Inhibition of lung TNFR1 is selectively radioprotective for the lung without compromising tumor response. These findings support the development of a novel radioprotection strategy using inhibition of the TNF-alpha pathway.

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.

Transcriptional activation of p21 by Tranilast is mediated via transforming growth factor beta signal pathway

Tranilast, an antiallergic medication, is a very promising inhibitor of restenosis after balloon angioplasty. Tranilast can prevent the proliferation and migration of smooth muscle cells by activating the gene expression of p21, a strong cyclin/cyclin-dependent kinase (CDK) inhibitor, and by arresting cell growth at the G0/G1 phase. The signaling pathway of Tranilast in regulating p21 is to our best interest and is elucidated in the present study. The major emphasis was weighted on exploring the regulatory effects of Tranilast on promoter activity of p21. By serial deletion analysis, the sequence between -74 and -83 bp of the p21 promoter, previously identified as the transforming growth factor-beta (TGF-beta)-response element, was found sufficient, where as most of the promoter region 5' to -111 bp was found unnecessary for the transcriptional activation of p21 by both TGF-beta1 and Tranilast. Tranilast was also found to induce phosphorylation of Smad2 (a cytoplasmic signaling molecule essential for mediating TGF-beta signal transduction). Transfection of DeltakTbetaRII, a truncated form of TGF-beta type II receptor known to exert a dominant-negative effect on TGF-beta signaling, was found to suppress the signaling of both Tranilast and TGF-beta1 to a similar extent. These results suggested that induction of p21 by Tranilast might be closely related to TGF-beta signal transduction pathway.

Tranilast attenuates vascular hypertrophy, matrix accumulation and growth factor overexpression in experimental diabetes

OBJECTIVES

The growth factors transforming growth factor-B (TGF-B) and epidermal growth factor (EGF) have both been implicated in the hypertrophic structural changes in the vasculature that are characteristic features of both human and experimental diabetes. Recently, tranilast (N(3,4-dimethoxycinnamoyl)anthranilic acid), a drug used in the treatment of allergic and dermatological diseases, has also been reported to inhibit transforming growth factor-B (TGF-B)-mediated collagen formation. However, its effects on vascular hypertrophy in diabetes are unknown. The present study thus sought to determine the effects of tranilast on both TGF-B and EGF expression and mast cells in mediating the trophic vascular changes in experimental diabetes.

METHODS

Vessel morphology, growth factors and collagen gene expression and matrix deposition were examined in the mesenteric arteries of control rats treated with or without tranilast, and streptozotocin-induced diabetic Sprague-Dawley rats treated with or without tranilast (200 mg/kg/day) during a 3-week period.

RESULTS

Compared with control animals, diabetic rats had significantly increased vessel weight, wall: lumen ratio, ECM accumulation, gene expression of TGF-B1, EGF, and both alpha1 (I) and alpha1 (IV) collagen. Tranilast treatment did not influence plasma glucose or systemic blood pressure. However, tranilast significantly reduced mesenteric weight, wall: lumen ratio and matrix deposition and also attenuated the overexpression of TGF-B1, EGF, and both alpha1 (I) and alpha1 (IV) collagen mRNA in diabetic rats.

CONCLUSION

These findings indicate that tranilast ameliorates pathological vascular changes observed in experimental diabetes in association with reduced growth factor expression independent of blood glucose or systemic blood pressure.

Evolving Strategies for the Prevention and Treatment of Coronary Restenosis

Percutaneous coronary intervention has become an increasingly attractive alternative to medical therapy and surgical revascularization for the treatment of coronary artery disease. Over 1.5 million interventional procedures are performed annually worldwide, with the rate of procedures performed continuing to rise dramatically. Restenosis following percutaneous coronary intervention occurs at rates of 20% to 40% and has remained the Achilles heel of the procedure. Numerous early attempts at the prevention of restenosis with oral pharmacologic agents, such as antithrombotic therapies, lipid lowering agents, vasodilators, and growth factor inhibitors, failed to show benefit in clinical trials. The introduction of intracoronary stents resulted in a 30% reduction in restenosis rates by abolishing the early vessel recoil following angioplasty. However, as more complex lesions underwent percutaneous coronary intervention with stenting, rates of “in-stent” restenosis remained high (20% to 30%). With technologic advances and greater understanding of vascular pathobiology, novel therapeutic strategies, such as local delivery of ionizing radiation, immunosuppressive agents, and gene therapy, have been deployed to prevent coronary restenosis. In addition, a number of mechanical and radiation-based strategies have been used to treat those patients who develop restenosis. This review considers these emerging strategies for the prevention and treatment of restenosis.

Effects of antiasthma drugs on the growth of Chlamydophila pneumoniae in HEp-2 cells

A possible link between Chlamydophila pneumoniae infection and adult-onset asthma has been raised recently. To obtain further insight into the association of C. pneumoniae with asthma, we assessed the effects of antiasthma drugs commonly used in Japan on the growth of C. pneumoniae in HEp-2 cells. The growth was enhanced two times by inhalant glucocorticoids, such as fluticasone propionate and beclomethasone, as well as hydrocortisone succinate. Unexpectedly, two nonsteroidal antiasthma drugs, tranilast and seratrodast, an adenine nucleotide-lowering agent and a thromboxane A(2) receptor antagonist, respectively, were shown to inhibit chlamydial growth in vitro. The minimum inhibitory concentration and minimum chlamydicidal concentration were both 64 micrograms/ml, which are comparable to the peak serum levels achievable by a therapeutic dosage. These results suggest that some antiasthma drugs may affect the therapeutic outcome of C. pneumoniae-associated bronchial asthma by their effects on C. pneumoniae.

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.

State of the art in coronary intervention

Issues related to restenosis have been known since the beginning of coronary intervention, and by now, restenosis has been characterized in terms of its time course, pathophysiology, clinical presentation, and some of its histology. In 1984, the initial National Heart, Lung, and Blood Institute's percutaneous transluminal coronary angioplasty registry reported a restenosis rate of 33.6% and identified male gender, new unstable angina, diabetes mellitus, and treatment of bypass graft stenoses as risk factors. Today restenosis still occurs in 33% of patients, is still associated with recurrent angina, and occurs usually within several months after a successful intervention. These current conclusions are very interesting because we now treat a clearly different patient population. Clinical trials have documented that restenosis results in adverse clinical consequences. In recent large clinical trials involving patients with class B or C lesions, pharmacologic intervention with such agents as tranilast was still associated with a 33% restenosis rate and had no significant effect on major adverse cardiac events. More recently, drug-coated stents have been introduced and are undergoing testing in large clinical trials to definitively establish the long-term efficacy and safety suggested in their early promising experience. Thus, whether the solution for restenosis is at hand or whether we will continue to see patients who undergo successful intervention and develop restenosis only months later in the some position as the initial lesion remains an open issue.

Medical applications of transforming growth factor-beta

Transforming growth factor-beta (TGF-beta) proteins and their antagonists have entered clinical trials. These multi-functional regulators of cell growth and differentiation induce extracellular matrix proteins and suppress the immune system making TGF-betas useful in treatment of wounds with impaired healing, mucositis, fractures, ischemia-reperfusion injuries, and autoimmune disease. In diseases such as keloids, glomerulonephritis and pulmonary fibrosis, excessive expression of TGF-beta has been implicated as being responsible for accumulation of detrimental scar tissue. In these conditions, agents that block TGF-beta have prevented or reversed disease. Similarly, in carcinogenesis, blocking TGF-beta activity may be valuable in stimulating an immune response towards metastasis. As these blocking agents receive approval, we will likely have new therapies for previously recalcitrant diseases.

Tranilast inhibits cytokine-induced nuclear factor kappaB activation in vascular endothelial cells

Tranilast [N-(3,4-dimethoxycinnamoyl)anthranilic acid] inhibits vascular inflammation. However, the relevant anti-inflammatory mechanisms are not completely understood. We studied the effects of tranilast on nuclear factor-kappaB (NF-kappaB)-dependent endothelial cell adhesion molecule expression and transcriptional regulation. Cultured human umbilical vein endothelial cells were preincubated with 12.5 to 100 microg/ml tranilast. Tumor necrosis factor-alpha (TNF-alpha)-induced endothelial VCAM-1, ICAM-1, and E-selectin surface expression was inhibited dose dependently. Maximal inhibition achieved with 100 microg/ml tranilast was 38 +/- 6.9, 31.8 +/- 1.5, and 31.9 +/- 1.9%, respectively (mean +/- S.E.M., p < 0.001, n = 5). Secretion of interleukin 6, which is also NF-kappaB-sensitive, was significantly inhibited by tranilast. Endothelial MHC-I expression, which is independent of NF-kappaB, was not inhibited. Although cytokine-induced degradation of NF-kappaB inhibitor proteins (IkappaB-alpha, -beta, and -epsilon), nuclear translocation of NF-kappaB, and binding of NF-kappaB to kappaB cis-acting elements in the adhesion molecule promoters were not affected by tranilast, ICAM-1-kappaB and E-selectin-kappaB reporter gene activity was inhibited by 53% (n = 5, p < 0.01) and 51% (n = 5, p < 0.001), respectively. In contrast, using SP-1 and C/EBP constructs, reporter gene activity was not altered. Expression of the transcriptional coactivator cAMP response element binding protein binding protein (CBP) was inhibited by tranilast, resulting in a loss of interaction between NF-kappaB and CBP. Therefore, in therapeutically relevant concentrations (50 microg/ml), tranilast inhibits NF-kappaB-dependent transcriptional activation by interfering with the NF-kappaB/CBP association. We propose that inhibition of NF-kappaB dependent gene transcription contributes to the anti-inflammatory effects of tranilast.

Results of Prevention of REStenosis with Tranilast and its Outcomes (PRESTO) trial

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) is a major problem affecting 15% to 30% of patients after stent placement. No oral agent has shown a beneficial effect on restenosis or on associated major adverse cardiovascular events. In limited trials, the oral agent tranilast has been shown to decrease the frequency of angiographic restenosis after PCI.

METHODS AND RESULTS

In this double-blind, randomized, placebo-controlled trial of tranilast (300 and 450 mg BID for 1 or 3 months), 11 484 patients were enrolled. Enrollment and drug were initiated within 4 hours after successful PCI of at least 1 vessel. The primary end point was the first occurrence of death, myocardial infarction, or ischemia-driven target vessel revascularization within 9 months and was 15.8% in the placebo group and 15.5% to 16.1% in the tranilast groups (P=0.77 to 0.81). Myocardial infarction was the only component of major adverse cardiovascular events to show some evidence of a reduction with tranilast (450 mg BID for 3 months): 1.1% versus 1.8% with placebo (P=0.061 for intent-to-treat population). The primary reason for not completing treatment was > or =1 hepatic laboratory test abnormality (11.4% versus 0.2% with placebo, P<0.01). In the angiographic substudy composed of 2018 patients, minimal lumen diameter (MLD) was measured by quantitative coronary angiography. At follow-up, MLD was 1.76+/-0.77 mm in the placebo group, which was not different from MLD in the tranilast groups (1.72 to 1.78+/-0.76 to 80 mm, P=0.49 to 0.89). In a subset of these patients (n=1107), intravascular ultrasound was performed at follow-up. Plaque volume was not different between the placebo and tranilast groups (39.3 versus 37.5 to 46.1 mm(3), respectively; P=0.16 to 0.72).

CONCLUSIONS

Tranilast does not improve the quantitative measures of restenosis (angiographic and intravascular ultrasound) or its clinical sequelae.

Mouse genetic evidence that tranilast reduces smooth muscle cell hyperplasia via a p21(WAF1)-dependent pathway

OBJECTIVE

N-(3'4'-dimethoxycinnamoyl)-anthranilic acid (tranilast) is a drug that has been shown to reduce the incidence of restenosis after angioplasty in middle-scale clinical trials. Despite clinical interest in this drug, the pharmacological actions of tranilast remain relatively unexplored at a molecular level.

METHODS AND RESULTS

We evaluated the effects of tranilast on vascular smooth muscle cell (VSMC) proliferation in wild-type mice and in mice lacking a cyclin-dependent kinase inhibitor, p21(WAF1) (p21). Tranilast potently inhibited the proliferation of VSMC cultures derived from wild-type mice, but VSMCs derived from p21-deficient (p21-/-) mice were unaffected by this treatment. In a mouse femoral artery model of vascular injury, tranilast administration to wild-type mice led to an upregulation of p21 expression and a decrease in the number of proliferating VSMCs, as determined by immunostaining for proliferating cell nuclear antigen. In contrast, tranilast had no effect on the number of proliferating cell nuclear antigen-positive cells in the injured arteries of p21-/- mice. Administration of tranilast significantly reduced the neointimal VSMC hyperplasia in wild-type mice at 4 weeks but had no effect on lesion formation in p21-/- mice.

CONCLUSIONS

Our findings provide genetic evidence that tranilast inhibits intimal hyperplasia via a p21-dependent pathway, an activity that may contribute to its efficacy in the prophylactic treatment of postangioplasty restenosis.

Potential emerging therapeutic strategies to prevent restenosis in the peripheral vasculature

Despite the availability of antiplatelet and antithrombotic therapies, recent advances in catheter and stent technology and improved operator skill, restenosis remains the most frequent problem associated with percutaneous and surgical revascularization interventions for both coronary and peripheral arterial disease. Prevention of restenosis in the coronary vasculature has been demonstrated with cilostazol, trapidil, probucol, tranilast, nitric oxide donors, and clopidogrel. Given the similarities in revascularization procedures and in the pathophysiology of restenosis, it is possible that these results may be extrapolated to the setting of restenosis in the peripheral vasculature, making trials with these agents imperative. Several new agents have shown promising preliminary results for the prevention of restenosis in the peripheral vasculature, including cilostazol, low-molecular-weight heparins, and elastase. Several nonpharmacologic treatment modalities are also under study to prevent peripheral and coronary restenosis and have shown favorable initial results. These include endovascular radiation brachytherapy, arterial gene therapy, photoangioplasty, and several novel treatment delivery systems.

Tranilast prevents activation of transforming growth factor-beta system, leukocyte accumulation, and neointimal growth in porcine coronary arteries after stenting

N(3,4-dimethoxycinnamoyl) anthranilic acid (tranilast) prevents the synchronous upregulation of isoforms and receptors of the transforming growth factor (TGF)-beta system after arterial injury and reduces restenosis after human coronary angioplasty. However, the effects of tranilast and the importance of the TGF-beta system in stent restenosis, in which inward remodeling is unimportant but inflammatory cell stimulation of neointima formation is exaggerated, are uncertain. Boston minipigs, treated with tranilast or vehicle, were subjected to endoluminal stenting, and the expression of TGF-beta1 and TGF-beta3, the expression of their signaling receptors ALK-5 and TbetaR-II, leukocyte numbers around the stent struts, and neointima development were assessed over 28 days. Stenting greatly increased early (5-day) mRNA expression of the 2 TGF-beta isoforms and their receptors. Immunohistochemical localization later showed that their concentrations were greatest in regions adjacent to stent struts, where leukocytes and collagen deposition were prevalent. Tranilast suppressed these elevations in TGF-beta mRNAs and reduced their immunoreactive peptides detectable around stent struts. The accumulation of leukocytes and deposition of collagen in these regions was also greatly inhibited by tranilast. These effects were associated with a 48% reduction in maximal neointimal cross-sectional area and 43% reduction in mean neointimal cross-sectional area at 28 days (P<0.05). We conclude that tranilast suppresses neointima development after stenting, effects that can be at least partly attributed to its ability to attenuate the induction of the TGF-beta system and leukocyte accumulation around stent struts.

Antiproliferative effects of the antiallergic agent azelastine on human aortic smooth-muscle cells: an in vitro study

RATIONALE AND OBJECTIVES

The aim of the study was to examine the effects of azelastine on proliferation, clonogenic activity, cell-cycle, and migration of human aortic smooth-muscle cells (haSMCs) in vitro.

METHODS

HaSMCs were treated for 4 days with azelastine (1 micromol/L, 25 micromol/L, 50 micromol/L). Half of the treated groups were incubated again with azelastine, the other half received azelastine-free medium every 4 days until day 20. The growth kinetics and clonogenic activity were assessed. The cell-cycle distribution was investigated by FACS -- analysis and the migratory ability was evaluated.

RESULTS

Azelastine inhibited the proliferation and the clonogenic activity of haSMCs in a dose dependent manner. A G2/M-phase block was induced and the migratory ability was significantly impaired.

CONCLUSION

Azelastine has the potential to inhibit the proliferation of haSMCs. If a sufficient dose can be applied either systemically or locally it could be a valuable substance to prevent restenosis.

Inhibition of left ventricular fibrosis by tranilast in rats with renovascular hypertension

BACKGROUND

Growth factors such as transforming growth factor-beta (TGF beta) are believed to have an essential role in cardiac fibrosis. Tranilast (N(3,4-dimethoxycinnamoyl) anthranilic acid) attenuates the increased expression of TGF beta mRNA in vitro.

OBJECTIVE

To investigate whether tranilast reduces cardiac fibrosis in rats with two-kidney, one-clip (2K1C) renovascular hypertension. In addition, we tested the in-vitro effects of tranilast on cardiac myocytes and non-myocyte cells.

METHODS

We analysed hearts from four groups of rats: sham-operated controls; rats with 2K1C renovascular hypertension; rats with 2K1C renovascular hypertension treated for 12 weeks with the angiotensin converting enzyme (ACE) inhibitor, quinapril (6 mg/kg per day); rats with 2K1C renovascular hypertension treated for 12 weeks with tranilast (400 mg/kg per day).

RESULTS

Systolic blood pressure was reduced after quinapril treatment. Tranilast did not alter blood pressure (2K1C: 223 +/- 19 mmHg; 2K1C + quinapril: 149 +/- 15 mmHg (P < 0.01 compared with 2K1C); 2K1C + tranilast: 204 +/- 32 mmHg). Left ventricular weight was likewise reduced significantly by quinapril, but not significantly by tranilast (2K1C: 1.52 +/- 0.2 g; 2K1C + quinapril: 1.26 +/- 0.18 g (P < 0.05 compared with 2K1C); 2K1C + tranilast: 1.37 +/- 0.27 g). Using a computer-aided image analysis system, we demonstrated that tranilast prevented cardiac fibrosis in a blood-pressure-independent manner (P < 0.01 compared with 2K1C). Determination of the cardiac hydroxyproline content similarly revealed a significant reduction in cardiac fibrosis by tranilast (2K1C: 4.92 +/- 0.48 mg/mg; 2K1C + tranilast: 3.97 +/- 0.46 mg/mg; P < 0.05). The effect of tranilast on cardiac fibrosis was comparable to the effects of a blood-pressure-decreasing dose of the ACE inhibitor, quinapril. Cell culture experiments revealed that tranilast significantly decreased the proliferation of cardiac non-myocyte cells. Proliferation of cardiac myocytes was not altered.

CONCLUSION

This study revealed that long-term treatment with tranilast markedly attenuated left ventricular fibrosis in rats with renovascular hypertension. This was most probably the result of an antiproliferative effect of tranilast on cardiac non-myocyte cells. Tranilast thus offers a unique new therapeutic approach to the reduction of TGF beta-mediated cardiac fibrosis in vivo.

The impact of tranilast on restenosis after coronary angioplasty: the Second Tranilast Restenosis Following Angioplasty Trial (TREAT-2)

BACKGROUND

The Tranilast Restenosis Following Angioplasty Trial showed that oral administration of 600 mg/day of tranilast for 3 months markedly reduced the restenosis rate after percutaneous transluminal coronary angioplasty (PTCA) for de novo lesions.

METHODS

We conducted the second multicenter, randomized, double-blinded placebo-controlled trial. A total of 297 patients with 329 lesions were randomly assigned to treatment with tranilast or a placebo for 3 months after successful PTCA for both de novo and restenotic lesions. Angiographic follow-up examination was done at 3 months, and angiograms were interpreted with a quantitative approach.

RESULTS

Two hundred thirty-nine lesions (72.6%) in 216 of the patients (72.7%) met the criteria and were included in the assessment of restenosis. Lesion restenosis was defined as a loss of 50% or more of the initial gain, and the restenosis rates were 18.8% in the tranilast group (n = 112) and 44.1% in the placebo group (n = 127; P =.00005). The restenosis rate, defined as a percent stenosis of > or = 50% at follow-up examination, was also significantly lower in the tranilast group (25.9% versus 41.9%; P =.012). The numbers of restenotic lesions were 38 (33.9% of 112) in the tranilast group and 30 (23.6% of 127) in the placebo group. In restenotic lesions, the lesion restenosis rate was significantly lower in the tranilast subgroup (18.4% versus 53.3% with the first restenosis criterion; P =.004).

CONCLUSION

The oral administration of tranilast for 3 months markedly reduced the restenosis rate after PTCA, even in restenotic lesions.

Evidence for a role of mast cells in the evolution to congestive heart failure

Mast cells are believed to be involved in the pathophysiology of heart failure, but their precise role in the process is unknown. This study examined the role of mast cells in the progression of heart failure, using mast cell-deficient (WBB6F1-W/W(v)) mice and their congenic controls (wild-type [WT] mice). Systolic pressure overload was produced by banding of the abdominal aorta, and cardiac function was monitored over 15 wk. At 4 wk after aortic constriction, cardiac hypertrophy with preserved left ventricular performance (compensated hypertrophy) was observed in both W/W(v) and WT mice. Thereafter, left ventricular performance gradually decreased in WT mice, and pulmonary congestion became apparent at 15 wk (decompensated hypertrophy). In contrast, decompensation of cardiac function did not occur in W/W(v) mice; left ventricular performance was preserved throughout, and pulmonary congestion was not observed. Perivascular fibrosis and upregulation of mast cell chymase were all less apparent in W/W(v) mice. Treatment with tranilast, a mast cell-stabilizing agent, also prevented the evolution from compensated hypertrophy to heart failure. These observations suggest that mast cells play a critical role in the progression of heart failure. Stabilization of mast cells may represent a new approach in the management of heart failure.

Flufenamic acid: growth modulating effects on human aortic smooth muscle cells in vitro

PURPOSE

The aim of the study was to examine the effects of flufenamic acid on proliferation, clonogenic activity, migratory ability, cell-cycle distribution, and p44/42-mitogen-activated protein kinase (MAPK) expression on serum-stimulated human aortic smooth muscle cells (haSMCs) in vitro.

MATERIALS AND METHODS

HaSMCs were treated with flufenamic acid in three different doses (40 micromol/L, 200 micromol/L, 400 micromol/L) for 4 days, and then flufenamic-acid-free culture medium was supplemented every 4 days until day 20 after initial treatment. The growth kinetics were assessed. Cell-cycle analysis was performed by flow cytometry. The clonogenic activity was evaluated with use of colony formation assays. The migratory ability was investigated by stimulation with platelet derived growth factor (PDGF-BB) in 24 well plates with 8-microm pore membrane inserts. The p44/42 MAPK was detected by Western blot technique.

RESULTS

Flufenamic acid inhibited the proliferation (400 micromol/L treatment over 4 d; 179,700 +/- 49,800 vs 747,900 +/- 144,000; P <.001), clonogenic activity (400 micromol/L treatment over 4 d; 1 +/- 0.3 vs 50 +/- 1.4; P <.001) and migratory ability (400 micromol/L treatment over 4 d; 8 cells +/- 2 vs 48 cells +/- 15; P <.001) of haSMCs in a dose-dependent manner. Cell-cycle analysis revealed a G2/M-phase block (400 micromol/L treatment over 4 d; 28.9 +/- 1.5 vs 9.5 +/- 3.2; P <.001). The expression of p44/42 MAPK was reduced for a treatment with 400 micromol/L flufenamic acid (controls, 427 BLU +/- 0.305 vs treatment group, 190 BLU +/- 106; P <.05)

CONCLUSION

Flufenamic acid inhibits the proliferation and migration of haSMCs. Further experiments with animal models concerning stenosis and restenosis are necessary to evaluate the potential of this promising drug.

Tranilast inhibits transplant-associated coronary arteriosclerosis in a murine model of cardiac transplantation

Accelerated coronary arteriosclerosis remains a major problem for the long-term survival of cardiac transplant recipients. However, the pathogenesis of graft vasculopathy is poorly understood and there is no effective therapy. Tranilast is a promising drug that may prevent post-angioplasty restenosis. Here, we investigated whether orally administered tranilast inhibits the development of intima hyperplasia in a mouse model of cardiac transplantation. Cardiac allografts from BALB/c mice were transplanted heterotopically into C3H/He mice. Mice were administered either vehicle or tranilast everyday by gavage. Morphometrical analysis of the cardiac allografts harvested at 2 months revealed that the administration of tranilast significantly reduced the development of coronary atherosclerosis. In the mice treated with tranilast, up-regulation of the cyclin-dependent kinase inhibitor p21 was observed in the allografts, accompanied by a reduced number of proliferating cells. Tranilast also suppressed transforming growth factor-beta (TGF-beta) expression. Tranilast may be effective in preventing transplant-associated arteriosclerosis through its anti-inflammatory and anti-proliferative effects.

Overview of therapies for prevention of restenosis after coronary interventions

Coronary artery disease is a leading cause of morbidity and mortality in the United States and across the world. The economic impact of coronary artery disease is staggering and on the rise. Percutaneous transluminal coronary angioplasty is widely used to treat severe, symptomatic coronary stenosis. The Achilles heel of angioplasty is restenosis of those treated arteries. As a result, numerous therapies, including mechanical and pharmacological approaches, to prevent restenosis have been studied. A greater understanding of the pathophysiology of restenosis has enhanced the success of these therapeutic approaches. To date, the most important and successful approach to limit restenosis has been the use of coronary stents. Stents have reduced the rate of restenosis from approximately 50% down to 20-30%. However, in-stent restenosis presents a new and an even more challenging dilemma. The success of adjunctive drug therapy has been promising, but, as of yet, very limited. Antithrombotic agents have reduced acute thrombosis and many of the acute complications of angioplasty. New approaches and therapies are very encouraging, and provide great hope in the treatment of restenosis. Brachytherapy has shown success in the treatment of in-stent restenosis, and recently has been approved by the United States Food and Drug Administration for this indication. Drug-eluting stents using antiproliferative drugs are the most exciting new advance in preventing restenosis, currently in Phase III trials. Gene therapy, targeted drug delivery, and newer antithrombotic agents are also under investigation. We will review the pathophysiology of restenosis, animal models, pharmacological therapies, and mechanical approaches for the treatment of restenosis.

Mechanisms of angioplasty and stent restenosis: implications for design of rational therapy

Restenosis after angioplasty or stenting remains the major limitation of both procedures. A vast array of drug therapies has been used to prevent restenosis, but they have proven to be predominantly unsuccessful. Recent trends in drug therapy have attempted to refine the molecular and biological targets of therapy, based on the assumption that a single biological process or molecule is critical to restenosis. In contrast, both stenting and brachytherapy, which are highly nonspecific, can successfully reduce restenosis after angioplasty or stenting, respectively. This review examines the biology of both angioplasty and stent stenosis, focussing on human studies. We also review the landmark human trials that have definitively proven successful therapies, such as stenting and brachytherapy. We suggest that the successful trials of stenting and brachytherapy and the failure of other treatments have highlighted the shortcomings of conventional animal models of arterial intervention, and gaps in our knowledge of human disease. In contrast to arguments advocating gene therapy, these studies suggest that the most likely successful drug therapy will have a wide therapeutic range, targeting as many of the components or biological processes contributing to restenosis as possible.

Tranilast inhibits cardiac allograft vasculopathy in association with p21(Waf1/Cip1) expression on neointimal cells in murine cardiac transplantation model

Cardiac allograft vasculopathy is a major complication after cardiac transplantation, often limiting long-term recipient survival. N-(3,4-Dimethoxycinnamoyl)anthranilic acid (tranilast) inhibits cyclin-dependent kinase activity through p21(Waf1/Cip1) induction and arrests vascular smooth muscle cell proliferation in vitro. We tested a hypothesis that tranilast inhibits the vasculopathy characterized by diffuse intimal thickening in a murine heart transplantation model. Hearts from DBA/2 mice were heterotopically transplanted into B10.D2 mice as allografts. Oral administration of tranilast started 3 days before transplantation at doses of 550 or 1040 mg/kg per day until the animals were killed. Cardiac allograft vasculopathy was defined as luminal stenosis caused by neointimal formation. The percentage of luminal stenosis and cardiac rejection were analyzed 14 and 28 days after transplantation. Tranilast administration was associated with a marked reduction in luminal occlusion but with no significant effect on cardiac rejection. Immunohistochemical study of the tranilast-treated graft coronary arteries revealed enhancement of p21(Waf1/Cip1) and decreased expression of proliferating cell nuclear antigen in the neointima. The significant reduction in allograft vasculopathy concomitant with the enhancement of p21(Waf1/Cip1) indicates that tranilast has an antiproliferative effect that could be applicable to clinical treatment of cardiac allograft vasculopathy.

New developments in percutaneous coronary intervention

The field of percutaneous coronary intervention continues to progress at a tremendous rate. Advances in techniques, in device technology, and in adjunctive therapy have increased significantly the number of patients who may benefit from angioplasty and have increased the early and long-term success rates of these procedures. Future progress in radiation therapy, IIb/IIIa inhibitors, stent design, and other novel approaches undoubtedly will offer further improvements in the capability of coronary interventions to help patients live longer and feel better.

Vascular smooth muscle cell proliferation is effectively suppressed by the non-specific growth factor inhibitor suramin

The purpose of this study was to investigate the effects of the non-specific growth factor inhibitor suramin on smooth muscle cell proliferation in vitro and in vivo. Cultured vascular smooth muscle cells (VSMC) were stimulated by platelet-derived growth factor (PDGF) and cellular DNA synthesis assessed by [3H]-thymidine uptake. Suramin dose-dependently inhibited DNA synthesis in VSMC, and 100 microM of suramin completely suppressed the PDGF-AB-induced cellular DNA synthesis. Rabbit carotid arteries were injured by the balloon catheter, and then suramin locally delivered using a porous balloon catheter over ten minutes. Three weeks after the vascular injury, the extent of intimal thickening was compared between the suramin-treated and control rabbits. The neointimal formation triggered by balloon-mediated vascular injury was suppressed significantly and dose-dependently by locally infused suramin, and the intima to media area ratios of the control and 1 mM suramin-treated animals were 48.8+/-14.9 and 12.2+/-6.0%, respectively (p < 0.01. n = 6 for each group). These results suggest that one time local administration of suramin was sufficient to suppress neointimal formation after balloon-mediated vascular injury, and that pharmacological intervention targeting the growth factor's signaling pathways could be a promising approach to prevent smooth muscle cell proliferation in various proliferative vascular diseases.

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.

Reduction in left ventricular messenger RNA for transforming growth factor beta(1) attenuates left ventricular fibrosis and improves survival without lowering blood pressure in the hypertensive TGR(mRen2)27 Rat

Angiotensin II recruits transforming growth factor beta(1) (TGFbeta(1)) and is related to left ventricular fibrosis. However, it is unclear whether chronic in vivo reduction in left ventricular TGFbeta(1) expression blunts fibrosis and improves outcome in angiotensin II-dependent hypertension. Four-week-old male hypertensive TGR(mRen2)27 (Ren2) rats received either normal food, low-dose losartan (0.5 mg. kg(-1). d(-1)), or tranilast (a nonspecific TGFbeta inhibitor; 400 mg. kg(-1). d(-1)) (n=10 for each group) for 12 weeks and were compared with Sprague-Dawley control rats. The effect of tranilast on survival was evaluated in 34 additional untreated homozygous Ren2 rats. Tranilast or low-dose losartan did not lower blood pressure. However, the increase in left ventricular weight (Ren2 versus SD 3.1+/-0.16 versus 2.1+/- 0.06 mg/g body wt; P<0.05) was significantly (P<0.05) blunted by both tranilast (2.7+/-0.05) and losartan (2.7+/-0.07). Both drugs prevented the increase in left ventricular TGFbeta(1) mRNA and fibronectin mRNA and blunted the increase in hydroxyproline content and the increase in perivascular fibrosis. The perivascular fibrosis score correlated significantly with the level of expression of TGFbeta(1) (r=0.62; P=0.019). In situ hybridization demonstrated increases in TGFbeta(1) mRNA, predominantly in perivascular and nonmyocyte areas. Both drugs did not prevent the decrease in systolic or diastolic dP/dt, but tranilast significantly improved the survival of untreated Ren2 rats (P=0.029). In conclusion, TGFbeta(1) mRNA expression is increased predominantly in nonmyocyte regions in the hypertrophied left ventricle in this angiotensin II-dependent model of hypertension. This increase is probably due to high angiotensin II levels rather than to hypertension. This is the first study to suggest that chronic inhibition of TGFbeta(1) expression attenuates left ventricular hypertrophy and fibrosis, even without lowering blood pressure.

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.

Final results of the STent versus directional coronary Atherectomy Randomized Trial (START)

OBJECTIVES

This study was designed to compare primary stenting with optimal directional coronary atherectomy (DCA).

BACKGROUND

No previous prospective randomized trial comparing stenting and DCA has been performed.

METHODS

One hundred and twenty-two lesions suitable for both Palmaz-Schatz stenting and DCA were randomly assigned to stent (62 lesions) or DCA (60 lesions) arm. Single or multiple stents were implanted with high-pressure dilation in the stent arm. Aggressive debulking using intravascular ultrasound (IVUS) was performed in the DCA arm. Serial quantitative angiography and IVUS were performed preprocedure, postprocedure and at six months. The primary end point was restenosis, defined as > or =50% diameter stenosis at six months. Clinical event rates at one year were also assessed.

RESULTS

Baseline characteristics were similar. Procedural success was achieved in all lesions. Although the postprocedural lumen diameter was similar (2.79 vs. 2.90 mm, stent vs. DCA), the follow-up lumen diameter was significantly smaller (1.89 vs. 2.18 mm; p = 0.023) in the stent arm. The IVUS revealed that intimal proliferation was significantly larger in the stent arm than in the DCA arm (3.1 vs. 1.1 mm ; p < 0.0001), which accounted for the significantly smaller follow-up lumen area of the stent arm (5.3 vs. 7.0 mm2; p = 0.030). Restenosis was significantly lower (32.8% vs. 15.8%; p = 0.032), and target vessel failure at one year tended to be lower in the DCA arm (33.9% vs. 18.3%; p = 0.056).

CONCLUSIONS

These results suggest that aggressive DCA may provide superior angiographic and clinical outcomes to primary stenting.

Clinical trials in interventional cardiology

Several well-designed, randomized trials and registries have recently been completed in patients undergoing percutaneous coronary intervention (PCI) for the treatment of symptomatic coronary artery disease. These studies have further clarified the value of newer pharmacologic and mechanical approaches to patients with atherosclerotic disease and have resulted in improved clinical outcomes in patients undergoing PCI. As a result, many of the older paradigms of lesion-specific device selection have been revised to include the intricate balance of devices and drugs, tailored to the specific clinical presentation and lesion morphology in patients undergoing PCI. This article reviews several recent clinical trials and discusses their impact on early and late outcomes in patients undergoing PCI for symptomatic coronary artery disease.

Suppression of atherosclerotic development in Watanabe heritable hyperlipidemic rabbits treated with an oral antiallergic drug, tranilast

BACKGROUND

Inflammatory and immunological responses of vascular cells have been shown to play a significant role in the progression of atheromatous formation. Tranilast [N-(3,4-dimethoxycinnamoyl) anthranillic acid] inhibits release of cytokines and chemical mediators from various cells, including macrophages, leading to suppression of inflammatory and immunological responses. This study tested whether tranilast may suppress atheromatous formation in Watanabe heritable hyperlipidemic (WHHL) rabbits.

METHODS AND RESULTS

WHHL rabbits (2 months old) were given either 300 mg x kg-1 x d-1 of tranilast (Tranilast, n=12) or vehicle (Control, n=13) PO for 6 months. Tranilast treatment was found to suppress the aortic area covered with plaque. Immunohistochemical analysis showed that there was no difference in the percentage of the RAM11-positive macrophage area and the frequency of CD5-positive cells (T cells) in intimal plaques between Tranilast and Control. Major histocompatibility complex (MHC) class II expression in macrophages and interleukin-2 (IL-2) receptor expression in T cells, as markers of the immunological activation in these cells, was suppressed in atheromatous plaque by tranilast treatment. Flow cytometry analysis of isolated human and rabbit peripheral blood mononuclear cells showed that an increase in expression both of MHC class II antigen on monocytes by incubation with interferon-gamma and of IL-2 receptor on T cells by IL-2 was suppressed by the combined incubation with tranilast.

CONCLUSIONS

The results indicate that tranilast suppresses atherosclerotic development partly through direct inhibition of immunological activation of monocytes/macrophages and T cells in the atheromatous plaque.

Short-term treatment with prostaglandin E1 analogue has long-term preventive effects on intimal thickening in balloon-injured rat carotid arteries

We examined effects of a prostaglandin E1 analogue alprostadil on intimal thickening and arterial remodeling in balloon-injured rat carotid arteries. Right common carotid arteries were balloon-injured, and their left counterparts were sham-operated (uninjured). Rats were given alprostadil (0.3 microgram/kg/min, continuous subcutaneous (s.c.) infusion) or vehicle for 1 week after the injury and sacrificed at 4 weeks or 8 weeks. Segments of common carotid arteries corresponding to balloon-injured and uninjured sites were excised and subjected to elastica van Gieson staining. Cross-sectional areas were measured by computed planimetry. Alprostadil prevented intimal thickening at both 4 and 8 weeks. In addition, alprostadil prevented the increase in intimal area/area surrounded by external elastic lamina at both 4 and 8 weeks. Alprostadil had no effects on body weight, heart rate, or systolic blood pressure. Our study demonstrated that alprostadil administered only for the initial 1 week had long-term (up to 8 weeks) preventive effects on intimal thickening. Alprostadil may be useful to prevent restenosis after balloon angioplasty.