Prominent inhibitory effects of tranilast on migration and proliferation of and collagen synthesis by vascular smooth muscle cells

Functionalization of Silicone Surface with Drugs and Polymers for Regulation of Capsular Contracture

Breast reconstruction is achieved using silicone implants, which are currently associated with major complications. Several strategies have been considered to overcome the existing limitations as well as to improve their performance. Recently, surface modification has proved to be an effective clinical approach to prevent bacterial adhesion, reduce capsular thickness, prevent foreign body reactions, and reduce other implant-associated problems. This review article summarizes the ongoing strategies for the surface modification of silicone implants in breast reconstruction applications. The article mostly discusses two broad categories of surface modification: drug-mediated and polymer-based. Different kinds of drugs have been applied with silicone that are associated with breast reconstruction. Initially, this article discusses studies related to drugs immobilized on silicone implants, focusing on drug-loading methods and their effects on capsule contracture. Moreover, the pharmacological action of drugs on fibroblast cells is considered in this section. Next, the polymeric modification of the silicone surface is introduced, and we discuss its role in reducing capsule thickness at the cellular and biological levels. The polymeric modification techniques, their chemistry, and their physical properties are described in detail. Notably, polymer activities on macrophages and inflammation are also briefly discussed. Each of the reviewed articles is summarized, highlighting their discussion of capsular thickness, foreign body reactions, and bacterial attachment. The aim of this review is to provide the main points of some research articles regarding the surface modification of silicon, which can lead to a decrease in capsular thickness and provides better patient compliance.

Cytoprotective effects of Avenathramide C against oxidative and inflammatory stress in normal human dermal fibroblasts

Natural polyphenols are promising anti-aging compounds not only for their antioxidant activity, but also their ability to activate specific cellular pathways mediating the aging process. Avenanthramide C (Avn C), found exclusively in oats, is a natural antioxidant associated with free radical scavenging; however, it is how this compound elicits other protective effects. We investigated the intracellular antioxidant activity of Avn C and other cytoprotective potential in normal human skin fibroblasts exposed to extracellular stress. Avn C reduced H2O2-induced oxidative stress by reducing intracellular free radical levels and antioxidant gene transcripts. Avn C also resulted in decreased levels of gene transcripts encoding pro-inflammatory cytokines in response to H2O2 or tumor necrosis factor-α (TNF-α). This reduction in cytokine gene transcription occurred concomitantly with reduced phosphorylated nuclear factor-κB (NF-κB) p65, and decreased NF-κB DNA binding. Avn C further induced heme oxygense-1 (HO-1) expression through increased Nrf2 DNA binding activity, demonstrating a second mechanism by which Avn C attenuates cellular stress. Collectively, our findings indicate that Avn C protects normal human skin fibroblasts against oxidative stress and inflammatory response through NF-κB inhibition and Nrf2/HO-1 activation.

Importance of human peritoneal mesothelial cells in the progression, fibrosis, and control of gastric cancer: inhibition of growth and fibrosis by tranilast

BACKGROUND

Scirrhous gastric cancer is an intractable disease with a high incidence of peritoneal dissemination and obstructive symptoms (e.g., ileus, jaundice, and hydronephrosis) arising from accompanying marked fibrosis. Microenvironmental interactions between cancer cells and cancer-associated fibroblasts are the suggested cause of the disease. We elucidated the mechanisms of tumor growth and fibrosis using human peritoneal mesothelial cells (HPMCs) and investigated the effects of tranilast treatment on cells and a xenograft mouse model of fibrosis.

METHODS

HPMCs were isolated from surgically excised omentum and their interaction with MKN-45 gastric cancer cells was investigated using co-culture. Furthermore, a fibrosis tumor model was developed based on subcutaneous transplantation of co-cultured cells into the dorsal side of nude mice to form large fibrotic tumors. Mice were subsequently treated with or without tranilast.

RESULTS

The morphology of HPMCs treated with transforming growth factor (TGF)-β1 changed from cobblestone to spindle-type. Moreover, E-cadherin was weakly expressed whereas high levels of α-smooth muscle actin expression were observed. TGF-β-mediated epithelial-mesenchymal transition-like changes in HPMCs were inhibited in a dose-dependent manner following tranilast treatment through inhibition of Smad2 phosphorylation. In the mouse model, tumor size decreased significantly and fibrosis was inhibited in the tranilast treatment group compared with that in the control group.

CONCLUSIONS

Tranilast acts on the TGF-β/Smad pathway to inhibit interactions between cancer cells and cancer-associated fibroblasts, thereby inhibiting tumor growth and fibrosis. This study supports the hypothesis that tranilast represents a novel strategy to prevent fibrous tumor establishment represented by peritoneal dissemination.

Scar management in burn injuries using drug delivery and molecular signaling: Current treatments and future directions

In recent decades, there have been tremendous improvements in burn care that have allowed patients to survive severe burn injuries that were once fatal. However, a major limitation of burn care currently is the development of hypertrophic scars in approximately 70% of patients. This significantly decreases the quality of life for patients due to the physical and psychosocial symptoms associated with scarring. Current approaches to manage scarring include surgical techniques and non-surgical methods such as laser therapy, steroid injections, and compression therapy. These treatments are limited in their effectiveness and regularly fail to manage symptoms. As a result, the development of novel treatments that aim to improve outcomes and quality of life is imperative. Drug delivery that targets the molecular cascades of wound healing to attenuate or prevent hypertrophic scarring is a promising approach that has therapeutic potential. In this review, we discuss current treatments for scar management after burn injury, and how drug delivery targeting molecular signaling can lead to new therapeutic strategies.

Evaluation of the Combination of Methylprednisolone and Tranilast after Spinal Cord Injury in Rat Models

Objective

The aim of our study was to evaluate the neuroprotective functions of the combination therapy using methylprednisolone (MP) and tranilast (TR) after spinal cord injury (SCI) in adult rats.

Methods

Spinal cord compression injury model was achieved using Yasargil aneurysm clip. Rats were divided into control group, MP group, TR group, and combination therapy group using TR and MP. Rat models were assessed for locomotor functional recovery using Basso, Beattie, and Bresnahan (BBB) score, spinal cord water content and myeloperoxidase (MPO) activity 24 hours post SCI, haematoxylin and eosin staining and glial fibrillary acid protein (GFAP) staining at 7 and 14 days post SCI.

Results

The spinal cord water content and MPO activity in the combination therapy group was significantly lower than the control group and the individual therapy groups p<0.05. The combination therapy group had significantly higher BBB scores than control group and individual therapy groups (p<0.05). At one week after SCI, GFAP expression in the combination group was significantly lower than the control group (p<0.05) but there was no significant difference compared to the individual therapy groups (p>0.05). At 2 weeks after SCI there was a slight decrease in GFAP expression compared to the first week but the difference was not statistically significant (p>0.05), GFAP expression between the groups was not statistically significant p>0.05.

Conclusion

Combining MP and TR is therapeutically more effective in improving functional recovery, inhibiting inflammation and glial scar formation after acute SCI.

Tranilast inhibits the function of cancer-associated fibroblasts responsible for the induction of immune suppressor cell types

Cancer-associated fibroblasts (CAFs) are the dominant stromal component in the tumour microenvironment (TME), playing critical roles in generation of pro-tumourigenic TME; however, their contribution to suppression of antitumour immune responses has not been fully understood. To elucidate the interaction between CAFs and immune suppressor cells, we examined whether inhibition of CAFs function would impair the induction of immune suppressor cell types in vitro. In this study, we applied an anti-allergic and antifibrotic agent tranilast, which is used clinically, and evaluated a potential of tranilast to serve as a CAFs inhibitor. CAFs that had been isolated from E.G7 or LLC1 tumour-bearing mice were cultured in the presence of tranilast, and thereafter, CAFs functions on the secretion of some soluble factors as well as the induction of immune suppressor cells were evaluated. As a result, tranilast inhibited the proliferation of CAFs and reduced the levels of stromal cell-derived factor-1, prostaglandin E2 and transforming growth factor-β1 from CAFs in a dose-dependent manner. On the other hand, tranilast exerted no inhibitory effects on immune cells at doses under 100 μm. The induction of regulatory T cells and myeloid-derived suppressor cells from their progenitor cells was suppressed in the medium that CAFs had been cultured in the presence of tranilast; however, these findings were not observed when those progenitor cells were cultured in the medium containing tranilast alone. These data demonstrate that tranilast inhibits CAFs function, which is responsible for the induction of immune suppressor cells, and possesses a potential to serve as a specific CAFs inhibitor.

Cancer-associated fibroblast-targeted strategy enhances antitumor immune responses in dendritic cell-based vaccine

Given the close interaction between tumor cells and stromal cells in the tumor microenvironment (TME), TME-targeted strategies would be promising for developing integrated cancer immunotherapy. Cancer-associated fibroblasts (CAFs) are the dominant stromal component, playing critical roles in generation of the pro-tumorigenic TME. We focused on the immunosuppressive trait of CAFs, and systematically explored the alteration of tumor-associated immune responses by CAF-targeted therapy. C57BL/6 mice s.c. bearing syngeneic E.G7 lymphoma, LLC1 Lewis lung cancer, or B16F1 melanoma were treated with an anti-fibrotic agent, tranilast, to inhibit CAF function. The infiltration of immune suppressor cell types, including regulatory T cells and myeloid-derived suppressor cells, in the TME was effectively decreased through reduction of stromal cell-derived factor-1, prostaglandin E2 , and transforming growth factor-β. In tumor-draining lymph nodes, these immune suppressor cell types were significantly decreased, leading to activation of tumor-associated antigen-specific CD8(+) T cells. In addition, CAF-targeted therapy synergistically enhanced multiple types of systemic antitumor immune responses such as the cytotoxic CD8(+) T cell response, natural killer activity, and antitumor humoral immunity in combination with dendritic cell-based vaccines; however, the suppressive effect on tumor growth was not observed in tumor-bearing SCID mice. These data indicate that systemic antitumor immune responses by various immunologic cell types are required to bring out the efficacy of CAF-targeted therapy, and these effects are enhanced when combined with effector-stimulatory immunotherapy such as dendritic cell-based vaccines. Our mouse model provides a novel rationale with TME-targeted strategy for the development of cell-based cancer immunotherapy.

Inhibition of transforming growth factor-β release from tumor cells reduces their motility associated with epithelial-mesenchymal transition

The high level of transforming growth factor‑β (TGF‑β) in tumor tissue, which is primarily released from tumor cells, helps maintain their metastatic nature and exacerbates the creation of a pro-tumor microenvironment. Although the strategy of targeting TGF‑β in cancer therapy has shown promise, its effects remain limited. In the present study, we focused on tumor cells as sources of TGF‑β release, and hypothesized that inhibition of their TGF‑β release could suppress their epithelial-mesenchymal transition (EMT)-associated metastatic nature and inactivate the induction of suppressor immune cells. To investigate this hypothesis, LLC1 cells, a mouse lung cancer cell line, were cultured with the TGF‑β release inhibitor tranilast and the motility of LLC1 cells was examined. Furthermore, to examine whether inhibition of TGF‑β release influences the induction of regulatory T (Treg) cells, spleen cells from normal mice were cultured in medium in which LLC1 cells had been cultured with tranilast. The results showed that tranilast inhibited the release of TGF‑β1 from LLC1 cells without affecting their proliferation. Inhibition of TGF‑β1 release suppressed the invasive activity of LLC1 cells, but enhanced their activity to adhere. mRNA levels of Slug and Twist were decreased in LLC1 cells, whereas levels of E‑cadherin were recovered. Treg cells were less frequently induced by medium in which LLC1 cells had been cultured with tranilast. Taken together, inhibition of TGF‑β1 release dampens the metastatic nature of LLC1 cells through the downregulation of EMT and possesses the possibility to improve antitumor immune responses through suppression of Treg cell induction. These findings provide a new rationale for development of TGF‑β‑targeted molecular immunotherapy against cancer.

Suppression of the allogeneic response by the anti-allergy drug N-(3,4-dimethoxycinnamonyl) anthranilic acid results from T-cell cycle arrest

Previously we have shown that indoleamine 2,3-dioxygenase (IDO) and the tryptophan metabolite, 3-hydroxykynurenine (3HK) can prolong corneal allograft survival. IDO modulates the immune response by depletion of the essential amino acid tryptophan by breakdown to kynurenines, which themselves act directly on T lymphocytes. The tryptophan metabolite analogue N-(3,4-dimethoxycinnamonyl) anthranilic acid (DAA, 'Tranilast') shares the anthranilic acid core with 3HK. Systemic administration of DAA to mice receiving a fully MHC-mismatched allograft of cornea or skin resulted in significant delay in rejection (median survival of controls 12 days, 13 days for cornea and skin grafts, respectively, and of treated mice 24 days (P < 0.0001) and 17 days (P < 0.03), respectively). We provide evidence that DAA-induced suppression of the allogeneic response, in contrast to that induced by tryptophan metabolites, was a result of cell cycle arrest rather than T-cell death. Cell cycle arrest was mediated by up-regulation of the cell cycle-specific inhibitors p21 and p15, and associated with a significant reduction in interleukin-2 production, allowing us to characterize a novel mechanism for DAA-induced T-cell anergy. Currently licensed as an anti-allergy drug, the oral bioavailability and safe therapeutic profile of DAA make it a candidate for the prevention of rejection of transplanted cornea and other tissues.

Potential health benefits of avenanthramides of oats

Oats are known to be a healthy food for the heart due mainly to their high beta-glucan content. In addition, they contain more than 20 unique polyphenols, avenanthramides, which have shown strong antioxidant activity in vitro and in vivo. The polyphenols of oats have also recently been shown to exhibit anti-inflammatory, antiproliferative, and anti-itching activity, which may provide additional protection against coronary heart disease, colon cancer, and skin irritation.

Prevention and management of hypertrophic scars and keloids after burns in children

Hypertrophic scars and keloids are challenging to manage, particularly as sequelae of burns in children in whom the psychologic burden and skin characteristics differ substantially from adults. Prevention of hypertrophic scars and keloids after burns is currently the best strategy in their management to avoid permanent functional and aesthetical alterations. Several actions can be taken to prevent their occurrence, including parental and children education regarding handling sources of fire and flammable materials, among others. Combination of therapies is the mainstay of current burn scar management, including surgical reconstruction, pressure therapy, silicon gels and sheets, and temporary garments. Other adjuvant therapies such as topical imiquimod, tacrolimus, and retinoids, as well as intralesional corticosteroids, 5-fluorouracil, interferons, and bleomycin, have been used with relative success. Cryosurgery and lasers have also been reported as alternatives. Newer treatments aimed at molecular targets such as cytokines, growth factors, and gene therapy, currently in developing stages, are considered the future of the treatment of postburn hypertrophic scars and keloids in children.

Approaches for prevention of restenosis

Coronary artery disease is characterized by a narrowing (stenosis) of the arteries that supply blood to the tissue of the heart. Continued restriction of blood flow manifests itself as angina and ultimately myocardial infarction (heart attack) for the patient. Heart bypass was once the only treatment for this condition, but over the years percutaneous coronary intervention (PCI) has become an increasingly attractive alternative to medical therapy and surgical revascularization for the treatment of coronary artery disease. A vascular stent is a medical device designed to serve as a temporary or permanent internal scaffold, to maintain or increase the lumen of a blood vessel. Metallic coronary stents were first introduced to prevent arterial dissections and to eliminate vessel recoil and intimal hyperplasia associated with PCI. Further advancement in the treatment of coronary artery disease is the development of drug-eluting stents that dramatically reduce the incidence of in-stent restenosis to less than 5%. Local drug delivery offers the advantages of allowing a relatively high local concentration of drug at the treatment site while minimizing systemic toxic effect. This review describes approaches for prevention of restenosis. It focuses on drugs for prevention of restenosis, bare metal stents, and drug-eluting stents. It also describes recent advances in bioresorbable stents. One of the chapters is dedicated to our novel composite bioresorbable drug-eluting fibers, designed to be used as basic elements in drug-eluting stents.

Paclitaxel-eluting composite fibers: drug release and tensile mechanical properties

New core/shell fiber structures loaded with paclitaxel were developed and studied. These composite fibers are ideal for forming thin, delicate, biomedically important structures for various applications. Possible applications include fiber-based endovascular stents that mechanically support blood vessels while delivering drugs for preventing restenosis directly to the blood vesel wall, or drug delivery systems for treatment of cancer. The core/shell fiber structures were formed by "coating" dense core fibers with porous paclitaxel-containing poly(DL-lactic-co-glycolic acid) (PDLGA) structures. Shell preparation ("coating") was performed by freeze-drying water in oil emulsions. The present study focused on the effects of the emulsion's formulation (composition) and processing conditions on the paclitaxel release profile and on the fibers' tensile mechanical properties. In general, the porous PDLGA shell released approximately 40% of the paclitaxel, with most of the release occurring during the first 30 days. The main release mechanism during the tested period is diffusion, rather than polymer degradation. The release rate and quantity increased with increased drug content or decreased polymer content, whereas the organic:aqueous phase ratio had practically no effect on the release profile. These new composite fibers are strong and flexible enough to be used as basic elements for stents. We demonstrated that proper selection of processing conditions based on kinetic and thermodynamic considerations can yield polymer/drug systems with the desired drug release behavior and good mechanical properties.

DRUG-ELUTING BIORESORBABLE STENTS FOR VARIOUS APPLICATIONS

A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. Metallic coronary stents were first introduced to prevent arterial dissections and to eliminate vessel recoil and intimal hyperplasia associated with percutaneous transluminal coronary angioplasty. The stent application range has expanded as more experience was gained, and encouraging results have been obtained in the treatment of vascular diseases. Stents are currently used for support of additional body conduits, including the urethra, trachea, and esophagus. The rationale for bioresorbable stents is the support of a body conduit only during its healing process. The stent mass and strength decrease with time, and the mechanical load is gradually transferred to the surrounding tissue. Bioresorbable stents also enable longer term delivery of drugs to the conduit wall from an internal reservoir and abolish the need for a second surgery to remove the device. The present review describes recent advances in bioresorbable stents, focusing on drug-eluting bioresorbable stents for various applications. Controlled release of an active agent from a stent can be used to enhance healing of the surrounding tissues, to increase the implant's biocompatibility, as well as to help cure certain diseases. Because a lot of research in this field has been done by us, examples for these functions are described based mainly on developments in our laboratories.

Effect of tranilast in early-stage diabetic nephropathy

BACKGROUND

Tranilast is an antifibrotic drug known to suppress collagen synthesis by fibroblasts by interfering with the effects of TGF-beta. We recently reported that it slowed the progression rate of advanced diabetic nephropathy (DN) by reducing the accumulation of collagens in renal tissue. The present study was undertaken to examine the effect of tranilast on early-stage DN.

METHODS

Among out-patients with diabetes mellitus, we selected patients with (i) urinary albumin excretion of 30-1000 mg/g creatinine (/gCr) in the first morning urine, (ii) serum creatinine (SCr) < or =1.2 mg/dl and no haematuria and (iii) currently taking an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. Twenty patients fulfilled the criteria, of whom 10 were selected at random and commenced on tranilast [100 mg, 3 times daily; T(+) group]. The remaining 10 patients comprised the T(-) group. Excretion of both urinary type IV collagen (U-IV) and albumin (U-A) in the first morning urine was measured every 3 months. The follow-up period was 1 year.

RESULTS

At baseline, no significant differences were observed in SCr, HbA(1c), blood pressure and U-A excretion between the T(+) and T(-) groups, but U-IV excretion in the T(+) group was higher than in the T(-) group (6.4 +/- 0.66 vs 3.7 +/- 0.36 microg/gCr, mean +/- SEM, P < 0.01). At 1 year, SCr was not different from the baseline in either group. In the T(+) group, however, excretion rates of both U-IV and U-A tended to decrease with time, and after 1 year, were significantly decreased compared with excretion at baseline (U-A: 279 +/- 78 to 191 +/- 62 mg/gCr; P = 0.049, U-IV: 6.4 +/- 0.66 to 4.4 +/- 0.99 microg/gCr; P = 0.02). In contrast, in the T(-) group, excretion of both U-A and U-IV tended to increase with time. The changes of both U-A and U-IV excretions in the two groups took statistically different trends through tranilast treatment (P = 0.01 and P = 0.04, respectively).

CONCLUSIONS

Our results suggest that tranilast could be therapeutically beneficial in early-stage DN.

Expression, localisation and function of ACE and chymase in normal and atherosclerotic human coronary arteries

The expression, localisation and function of enzymes responsible for the local formation of angiotensin II in atherosclerotic and non-atherosclerotic human coronary arteries were studied. Human epicardial coronary arteries expressed mRNA for both ACE and chymase. Immunohistochemical studies revealed that ACE was localised to the vascular endothelium, and to a lesser extent the medial smooth muscle cells, in both large and small arteries. Chymase was detected in both types of vessel but was shown to be associated with mast cells. The contractions to angiotensin I in large arteries were inhibited only by a combination of quinaprilat and soyabean trypsin inhibitor. In the intramyocardial arteries the response to angiotensin I was markedly inhibited in the presence of chymostatin. These findings demonstrate that a dual pathway for the synthesis of angiotensin II is active in diseased and non-diseased coronary arteries.

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.

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.

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.

Anti-tumor effect of N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast) on experimental pancreatic cancer

The anti-tumor effect of N- [3,4-dimethoxycinnamoyl] -anthranilic acid (tranilast) was examined in experimental pancreatic cancer. Proliferation of PGHAM-1 cells was inhibited by tranilast in a dose-dependent manner, showing a significant difference at a concentration of 25 microgram/ml (p<0.05). In colony formation, tranilast reduced the number of colonies at a concentration of 25 microgram/ml (p<0.01). DNA synthesis for 12 hours was attenuated dose-dependently and a significant difference was observed at concentrations of greater than 50 microgram/ml (p<0.05). From cell cycle analysis, a dose-dependent increase in the distribution of G0-G1 phase was observed. In the dorsal air sac model, the mean angiogenesis indices in PGHAM-1 chambers were 4.17 +/- 0.22 (control group) and 2.33 +/- 0.84 (treatment group), and in VEGF chambers they were 3.60 +/- 0.67 (control group) and 1.92 +/- 0.42 (treatment group), In the peritoneal dissemination model, the quantity of sanguineous ascites, the number and the size of diaphragmatic nodules and the microvessel density (MVD) of the metastatic site were reduced by tranilast significantly. In conclusion, the anti-tumor effect of tranilast on proliferation and on tumor-angiogenesis was confirmed in experimental pancreatic cancer.

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.

N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast) inhibits transforming growth factor-beta relesase and reduces migration and invasiveness of human malignant glioma cells

Extensive infiltration of normal brain tissue and suppression of anti-tumor immune surveillance mediated by molecules such as transforming growth factor-beta (TGF-beta) are key biological features that contribute to the malignant phenotype of human gliomas. Tranilast (N-[3,4-dimethoxycinnamoyl]-anthranilic acid) is an anti-allergic compound used clinically to control atopic and fibrotic disorders. These effects are attributed to the suppression of TGF-beta1 synthesis and interference with growth factor-mediated proliferation and migration of fibroblasts and vascular smooth muscle cells. Here, we show that tranilast inhibits DNA synthesis and proliferation of human malignant glioma cells and promotes p21 accumulation in the absence of cytotoxicity. Further, tranilast reduces the release of TGF-beta1 and TGF-beta2 by glioma cells and inhibits migration, chemotactic responses and invasiveness. These effects are not associated with a reduction of alpha(v)beta(3) integrin expression at the cell surface but appear to involve inhibition of matrix metalloproteinase-2 expression and activity. Neither the tranilast-mediated inhibition of proliferation nor the inhibition of migration was counteracted by supplementation with exogenous TGF-beta. Finally, tranilast administered orally inhibited the growth of experimental 9L rat gliomas and reduced expression of TGF-beta2 in vivo. We conclude that tranilast might be a useful therapeutic agent for the treatment of human malignant glioma because of a TGF-beta-independent abrogation of the malignant phenotype of proliferation, migration and invasiveness and because of the antagonism of TGF-beta-associated immunosuppression.

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.

Synthesis and structure-activity relationship of diarylamide derivatives as selective inhibitors of the proliferation of human coronary artery smooth muscle cells

A series of diarylamide derivatives were synthesized and evaluated for their inhibitory activities against human coronary artery smooth muscle cells (SMCs) and human coronary artery endothelial cells (ECs). Compound 2w was superior to the lead compound, Tranilast, in terms of the potency of the activity and cell selectivity.

Colchicine encapsulation within poly(ethylene glycol)-coated poly(lactic acid)/poly(epsilon-caprolactone) microspheres-controlled release studies

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Local delivery of agents capable of modulating vascular responses have the potential to prevent restenosis. However, the development of injectable microspheres for maintaining high tissue levels of drugs at the site of vascular injury is a major challenge. We demonstrated the possibility of entrapping an antiproliferative agent, colchicine, in polyethylene glycol (PEG)-coated biodegradable microspheres composed of poly(lactic acid)/poly(epsilon-caprolactone) blends, with a mean diameter of 3-6 microm. A solution of colchicine and blends of polylactic acid (PLA)/polycaprolactone (PCL) dissolved in acetone-dichloromethane mixture was poured into an aqueous solution of PEG (or polyvinyl alcohol) with stirring by a high-speed homogenizer to form microspheres. Colchicine recovery in microspheres ranged from 30-50% depending on the emulsification system and the ratio of polymer blends used for the preparations. Scanning electron microscopy revealed that the PLA/PCL microspheres were spherical in shape and had a smooth surface texture. Results of in vitro release studies showed that it is possible to control the colchicine release by choosing the appropriate particle size, loading, and PLA/PCL composition. Water permeability through the PLA membrane was greater, when compared with PCL blends. The amount of drug release also was much higher (58.3%) in PLA compared with PCL (39.3%) microspheres, for 30 days. Therefore, we concluded that the drug release from the microspheres followed a diffusion mechanism where bulk erosion and surface deposition were negligible. These PEG-coated PLA/PCL microspheres may have potential for targeting antiproliferative agents for prolonged periods to treat restenosis.

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.

Inhibitory effects of tranilast on the proliferation and functions of human pterygium-derived fibroblasts

PURPOSE

We studied the possibility that tranilast, an antiallergic and antiproliferative drug, may be beneficial for the treatment of pterygium.

METHODS

Pterygium-derived cells were identified by immunohistochemical methods. Growth rate of pterygium-derived cells was determined by using a hemocytometer. Chemotaxis was determined in a microchemotaxis chamber. Pterygium-derived cells were cultured on floating collagen gel, and the contracted diameter was measured. Collagen synthesis by pterygium-derived cells was determined by the collagenase digestive method. Tranilast was added to the culture medium at final concentrations of 0, 12.5, 25, 50, and 100 microg/ml.

RESULTS

Pterygium-derived cells were stained with anti-prolylhydroxylase and anti-alpha-smooth muscle actin, and identified as fibroblasts. Tranilast inhibited the proliferation and chemotaxis of pterygium-derived fibroblasts, and the collagen-gel contraction induced by these cells, but it exerted no inhibitory action on collagen synthesis by pterygium-derived fibroblasts.

CONCLUSION

Tranilast may be useful for suppressing the recurrence and, possibly, the development of pterygium.

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.

Inhibitory effect of methylene blue-induced photooxidation on intimal thickening of vein graft

BACKGROUND

We have previously speculated that methylene blue-induced photooxidation of adventitial surface for 5 minutes can completely inhibit the intimal and medial growth of surgically prepared saphenous vein in vitro. In this study, inhibitory effect of methylene blue-induced photooxidation on intimal thickening of vein graft in vivo was investigated.

METHODS

Jugular vein grafts were photooxidized in 0.01% methylene blue solution for 5 minutes, and interposed into arterial circulation for 4 weeks in rabbits. Vein grafts were studied by morphometry and immunohistochemistry.

RESULTS

The intimal thickening of photooxidized vein grafts were suppressed significantly compared with those in the nonphotooxidized group. Proliferated cell nuclear antigen (PCNA) index (total PCNA-positive cells/total cell count x 100%) of vein graft was significantly higher in the nonphotooxidized group than those in the photooxidized group.

CONCLUSIONS

Methylene blue-induced photooxidation is effective in the inhibition of intimal thickening of vein graft interposed in the arterial circulation for 4 weeks in vivo.

Liver fibrogenesis and the role of hepatic stellate cells: new insights and prospects for therapy

Hepatic fibrosis is a wound-healing response to chronic liver injury, which if persistent leads to cirrhosis and liver failure. Exciting progress has been made in understanding the mechanisms of hepatic fibrosis. Major advances include: (i) characterization of the components of extracellular matrix (ECM) in normal and fibrotic liver; (ii) identification of hepatic stellate cells as the primary source of ECM in liver fibrosis; (iii) elucidation of key cytokines, their cellular sources, modes of regulation, and signalling pathways involved in liver fibrogenesis; (iv) characterization of key matrix proteases and their inhibitors; (v) identification of apoptotic mediators in stellate cells and exploration of their roles during the resolution of liver injury. These advances have helped delineate a more comprehensive picture of liver fibrosis in which the central event is the activation of stellate cells, a transformation from quiescent vitamin A-rich cells to proliferative, fibrogenic and contractile myofibroblasts. The progress in understanding fibrogenic mechanisms brings the development of effective therapies closer to reality. In the future, targeting of stellate cells and fibrogenic mediators will be a mainstay of antifibrotic therapy. Points of therapeutic intervention may include: (i) removing the injurious stimuli; (ii) suppressing hepatic inflammation; (iii) down-regulating stellate cell activation; and (iv) promoting matrix degradation. The future prospects for effective antifibrotic treatment are more promising than ever for the millions of patients with chronic liver disease worldwide.

Tranilast suppresses vascular chymase expression and neointima formation in balloon-injured dog carotid artery

BACKGROUND

Activation of vascular chymase plays a major role in myointimal hypertrophy after vascular injury by augmenting the production of angiotensin (ANG) II. Because chymase is synthesized mainly in mast cells, we assumed that the chymase-dependent ANG II formation could be downregulated by tranilast, a mast cell-stabilizing antiallergic agent. We have assessed inhibitory effects of tranilast on neointima formation after balloon injury in the carotid artery of dogs, which share a similar ANG II-forming chymase with humans, and further explored the pathophysiological significance of vascular chymase.

METHODS AND RESULTS

Either tranilast (50 mg/kg BID) or vehicle was orally administered to beagles for 2 weeks before and 4 weeks after balloon injury. Four weeks after the injury, remarkable neointima was formed in the carotid arteries of vehicle-treated dogs. Chymase mRNA levels and chymaselike activity of vehicle-treated injured arteries were increased 10.2- and 4.8-fold, respectively, those of uninjured arteries. Angiotensin-converting enzyme (ACE) activity was slightly increased in the injured arteries, whereas ACE mRNA levels were not. Tranilast treatment completely prevented the increase in chymaselike activity, reduced the chymase mRNA levels by 43%, and decreased the carotid intima/media ratio by 63%. In vehicle-treated injured arteries, mast cell count in the adventitia showed a great increase, which was completely prevented by the tranilast treatment. Vascular ACE activity and mRNA levels were unaffected by tranilast.

CONCLUSIONS

Tranilast suppressed chymase gene expression, which was specifically activated in the injured arteries, and prevented neointima formation. Suppression of the chymase-dependent ANG II-forming pathway may contribute to the beneficial effects of tranilast.

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.

Preventive effects of an antiallergic drug, pemirolast potassium, on restenosis after percutaneous transluminal coronary angioplasty

BACKGROUND

We recently confirmed that pemirolast potassium, an antiallergic agent, markedly inhibits migration and proliferation of vascular smooth muscle cells. It has also been reported that pemirolast inhibits intimal hyperplasia in animal experiments.

METHODS AND RESULTS

To elucidate the preventive effects of pemirolast on restenosis after percutaneous transluminal coronary angioplasty (PTCA), 227 patients were enrolled in this prospective, randomized trial. A total of 205 patients who were compatible with the protocol were analyzed (pemirolast group, 104 patients with 140 lesions; control group, 101 patients with 133 lesions). Patients in the pemirolast group received 20 mg/d of pemirolast from 1 week before PTCA until the time of follow-up angiography (4 months after PTCA). Angiographic restenosis was defined as diameter stenosis >/=50% at follow-up. Restenosis rates were significantly lower in the pemirolast group than in the control group (24.0% vs 46.5% of patients, 18.6% vs 35.3% of lesions, P <.01, respectively). During 8 months of follow-up, there were no coronary events (death, myocardial infarction, coronary artery bypass surgery, or repeated PTCA) in 81.7% of the pemirolast group and in 63.4% of the control group (P =.013).

CONCLUSIONS

This study suggested that pemirolast would be useful in the clinical setting to prevent restenosis after PTCA.

Tranilast, an anti-allergic drug, possesses antagonistic potency to angiotensin II

N-(3',4'-dimethoxycinnamoyl) anthranilic acid (tranilast), an effective anti-allergic drug, has successfully prevented restenosis in patients who have undergone percutaneous transluminal coronary angioplasty. To elucidate the mechanism of tranilast, we investigated its antagonistic effect to angiotensin II, which plays a pivotal role in the proliferation of vascular smooth muscle cells, using angiotensin II-induced contractions in human gastroepiploic artery and rabbit aorta. The possible antagonistic effects of other anti-allergic agents such as 4-( p-chlorobenzyl)-2-(hexahydro-1-methyl-1H-azepin-4-yl)-1(2H)-phthal azinone hydrochloride (azelastine), 9-methyl-3-( 1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyramidin-4-one potassium salt (pemirolast) and disodium cromoglycate were also compared. Tranilast dose-dependently inhibited the angiotensin II-induced contractions in human and rabbit arteries (IC50 = 3.6x10(-5) M and pD'2 = 3.69, respectively). Pemirolast showed a weak antagonistic effect to angiotensin II, but the effective concentration cannot be administered in clinical dosage. Tranilast and pemirolast had no effect on the concentration-contractile response curves for KCI and norepinephrine. Azelastine inhibited angiotensin II-, KCl- and norepinephrine-induced contractions non-specifically, while disodium cromoglycate did not affect these contractile responses. Tranilast but not azelastine showed synergistic action with 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimi dazole-7-carboxylic acid (CV- 11974) in antagonizing angiotensin II-induced contraction and the inhibitory pattern was similar to that of the non-peptide angiotensin II AT1 receptor antagonist CV-11974. These findings indicate that only tranilast possesses the unique ability to antagonize angiotensin II in clinical dosage, which may contribute at least in part to prevention of restenosis after percutaneous transluminal coronary angioplasty.

Inhibition by tranilast of vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF)-induced increase in vascular permeability in rats

We studied the effects of tranilast, an anti-allergic and anti-proliferative drug in clinical use, on VEGF/VPF-induced vascular permeability in a rat air pouch model. A large increase in vascular permeability was induced by injection of 4 ml of a 100 ng/ml VEGF/VPF solution into the preformed air pouch. Over a 15-min period, tranilast inhibited the VEGF/VPF-induced vascular permeability in a dose-dependent manner. This result suggests that tranilast, which we recently found to inhibit VEGF/VPF-induced angiogenesis, could also improve VEGF/VPF-dependent increases in vascular permeability.

Photochemically induced endothelial injury in the mouse as a screening model for inhibitors of vascular intimal thickening

We have established a mouse model of intimal thickening and assessed its suitability for experimental studies of intimal thickening. Neointimal formation was observed after endothelial injury by photochemical reaction between transluminal green light and systemically administered rose Bengal, which represents a nonmechanical approach to vessel wall denudation. Intimal thickening began 7 days after endothelial injury, reached a maximum after 21 days, and then remained unchanged for as long as 42 days. Furthermore, as a consequence of neointimal proliferation, the luminal area gradually decreased. The cells in the neointimal layer were identified as smooth muscle cells by immunohistochemical staining with an alpha-actin-specific antibody. Extracellular matrix deposition in the neointima was markedly increased beyond 14 days after injury. Smooth muscle cell proliferation, as measured by pulse labeling of 5-bromo-2'-deoxyuridine, was identified initially in the media 2 days after vessel wall denudation, with the proliferative activity's shifting almost exclusively to the neointima within 7 days. Endothelial regeneration, as indicated by Evans blue staining, was complete within 21 days after injury. To assess the suitability of this model for experimental studies on intimal thickening, the effect of tranilast, an antiallergy drug with a broad spectrum of pharmacological actions on intimal thickening, was investigated. Tranilast (100 mg x kg(-1) x d(-1) p.o.) significantly (P<0.05) reduced smooth muscle cell proliferation in the neointima and media 7 days after injury and neointimal formation 21 days after injury in treated mice compared with vehicle-treated mice. This simple experimental mouse model is suitable for studying factors promoting or inhibiting intimal thickening after endothelial injury and for developing therapeutic strategies against intimal thickening.

The extracellular matrix in balloon arterial injury: a novel target for restenosis prevention

The role of the extracellular matrix (ECM) in the pathobiology of restenosis has not been fully appreciated. Recent discoveries have shown the ECM to be a complex, heterogeneous structure whose components are dynamically altered in response to vascular injury. This report reviews the structure and function of vascular ECM and the importance of the matrix in modulating the vascular response to arterial injury such as balloon angioplasty and atherosclerosis.

Synergistic inhibition of vascular smooth muscle cell migration by phosphodiesterase 3 and phosphodiesterase 4 inhibitors

Cyclic nucleotide phosphodiesterases (PDEs) hydrolyze cAMP or cGMP and terminate their signaling. Two important families of PDEs that regulate cAMP signaling in cardiovascular tissues are the cGMP-inhibited PDEs (PDE3) and the cAMP-specific PDEs (PDE4). In this study, we have used a combination of an in vitro motility assay and a sensitive method for the measurement of cAMP in order to determine the relative roles of PDE3 and of PDE4 in the regulation of cAMP-mediated inhibition of VSMC migration. Our data demonstrate that forskolin, an activator of adenylyl cyclases, causes concentration-dependent inhibition of platelet-derived growth factor-induced VSMC migration. Incubation of cultured VSMCs with a PDE4-selective inhibitor, Ro 20-1724, markedly potentiated both the antimigratory effect and the increase in cAMP caused by forskolin. Cilostamide, a PDE3-selective compound, did not affect either the antimigratory activity of forskolin or its ability to increase cAMP. Cilostamide and Ro 20-1724 interacted synergistically to potentiate the inhibition of VSMC migration by forskolin and caused a supra-additive increase in cAMP. These data are consistent with an important role for both PDE3 and PDE4 in the regulation of cAMP-mediated inhibition of VSMC migration.

Inhibitory effects of tranilast on expression of transforming growth factor-beta isoforms and receptors in injured arteries

Tranilast (N(3,4-dimethoxycinnamoyl)anthranilic acid), an agent which in cell culture inhibits transforming growth factor-beta (TGF-beta) secretion and antagonises the effects of TGF-beta and platelet-derived growth factor (PDGF) on cell migration and proliferation, has been reported to reduce the incidence of restenosis after angioplasty in angiographically validated human clinical trials. We investigated in a rat model of balloon angioplasty whether tranilast's effects in vivo could be attributed to inhibition of expression of TGF-beta and/or its receptor types. Using a standardised reverse transcriptase-polymerase chain reaction (RT-PCR) assay, we examined the effects of three doses of tranilast (25, 50 and 100 mg/kg) on the expression of two TGF-beta isoforms, the types I and II TGF-beta receptors and two putative TGF-beta responses, induction of integrins alpha(v) and beta3 mRNA, 2 h after oral administration and 26 h after vessel injury. Tranilast attenuated in a dose-dependent and reversible manner the injury-induced increases in mRNA levels encoding TGF-beta1, TGF-beta3, two type I TGF-beta receptors ALK-5 and ALK-2, and the type II receptor TbetaRII. At the highest dose mRNA levels encoding TGF-beta1 and TbetaRII were attenuated to levels approaching or below those observed in uninjured vessels. Messenger RNAs encoding TGF-beta3, ALK-5 and ALK-2 were all attenuated by between 70 and 74% (all P < 0.05). Tranilast also attenuated in a reversible manner the elevations in mRNA levels for integrins alpha(v) and beta3 observed after vessel injury, by 90 and 72%, respectively. We also investigated, in cultured smooth muscle cells derived from injured carotid arteries, the extent to which tranilast (300 mg/l) attenuated any increases in expression of type I and type II receptors stimulated by PDGF-BB and TGF-beta1, growth factors implicated in smooth muscle cell migration and proliferation in injured vessels. Increases in mRNA levels of the type I receptors ALK-5 and ALK-2 induced by PDGF-BB and TGF-beta1 were almost completely prevented by tranilast. Tranilast also prevented the PDGF-BB induced increases in TbetaRII but only partially inhibited the TGF-beta1 induced upregulation of TbetaRII. We conclude that tranilast can inhibit transcriptional mechanisms associated with the upregulation of TGF-beta and its receptor types in balloon catheter injured vessels. It is possible that these mechanisms contribute to its ability to reduce the frequency of restenosis after angioplasty.

Tranilast inhibits the proliferation, chemotaxis and tube formation of human microvascular endothelial cells in vitro and angiogenesis in vivo

1. First developed as an antiallergic drug, tranilast inhibits chemical mediator release from mast cells. In the present study, we examine the effects of tranilast on angiogenesis in vitro and in vivo and discuss the application of tranilast for angiogenic diseases. 2. Tranilast inhibited significantly the proliferation (IC50: 136 microM, 95% confidence limits: 134-137 microM) and vascular endothelium growth factor (VEGF)-induced chemotaxis (IC50: 135 microM, 95% confidence limits: 124-147 microM) of human dermal microvascular endothelial cells (HDMECs) at concentrations greater than 25 micrograms ml-1. No toxicity to HDMECs measuring by LDH release and no inhibitory effects on metalloproteinase (MMP)-2 and MMP-9 activity were observed even at 100 micrograms ml-1 (306 microM). 3. Tube formation of HDMECs cultured on the matrigel as an in vitro angiogenesis model was inhibited by tranilast in a concentration-dependent manner. The IC50 value and 95% confidence limits were 175 microM and 151-204 microM, respectively. 4. In vivo angiogenesis was induced in mice by the subcutaneous injection of matrigel containing 30 ng ml-1 VEGF and 64 micrograms ml-1 heparin. Tranilast was administered orally twice a day for 3 days. Tranilast dose-dependently suppressed angiogenesis in the matrigel and a significant change was observed at a dose of 300 mg kg-1. 5. These results indicate that tranilast is an angiogenesis inhibitor which may be beneficial for the improvement of angiogenic diseases such as proliferative diabetic retinopathy, age-related macular degeneration, tumour invasion and rheumatoid arthritis.

Effectiveness of tranilast on restenosis after directional coronary atherectomy

Tranilast is an antiallergic drug used widely in Japan that also inhibits the migration and proliferation of vascular smooth muscle cells. This pilot study was undertaken to determine the effectiveness of tranilast on restenosis after successful directional coronary atherectomy. After the procedure, 40 patients (56 lesions, tranilast group) were treated with oral tranilast for 3 months, and 152 patients (188 lesions, control group) did not receive tranilast. Angiographic and clinical variables were compared between the two groups. The minimal lumen diameter was significantly larger in the tranilast group than in the control group at both 3-month (2.08 vs 1.75 mm, p = 0.004) and 6-month follow-up (2.04 vs 1.70 mm, p = 0.003). The diameter stenosis in the tranilast group was smaller than that in the control group both 3 months (28% vs 40%, p = 0.0007) and 6 months (30% vs 43%, p = 0.0001) after the procedure, with a lower restenosis rate (percent diameter stenosis > or =50) in the tranilast group at 3 months (11 % vs 26%, p = 0.03). The number of clinical events over the 12-month period after the procedure was significantly reduced by tranilast administration (p = 0.013). These findings suggest that the oral administration of tranilast strongly prevents restenosis after directional coronary atherectomy.

Effects of pemirolast and tranilast on intimal thickening after arterial injury in the rat

We previously reported that tranilast, an antiallergic agent, reduced intimal thickening after endothelial injury in rats. In this study, to verify whether or not antiallergic agents inhibit intimal thickening, we investigated the effect of pemirolast on intimal thickening after endothelial injury and compared its effect with that of tranilast. Administration of two antiallergic agents, pemirolast (0.1, 1, and 10 mg/kg, p.o.) and tranilast (300 mg/kg, p.o., daily), was begun 2 days before endothelial injury and continued until the animals were killed. Endothelial injury in the rat femoral artery was induced by a photochemical reaction between localized irradiation by green light and intravenously administered rose bengal. To evaluate intimal hyperplasia, we measured the cross-sectional area of the intima 21 days after endothelial damage. Pemirolast at doses of 0.1, 1, and 10 mg/kg reduced the intimal area to 2.10 +/- 0.33, 1.36 +/- 0.19, and 1.35 +/- 0.18 (x0.01 mm2), respectively, and tranilast showed a tendency to reduce the intimal area, which was 1.86 +/- 0.35 x 0.01 mm2, compared with findings for controls (2.83 +/- 0.49 x 0.01 mm2). In rat A10 vascular smooth-muscle cells, we investigated the effects of antiallergic agents on migration by using a modified Boyden chamber assay and on proliferation by using the bromodeoxyuridine-incorporation assay. Two antiallergic agents inhibited in a concentration-dependent manner both migration and proliferation of smooth muscle cells stimulated by platelet-derived growth factor. These results suggest that antiallergic agents directly inhibit migration of smooth-muscle cells to the intima from the media and proliferation in the intima, and that pemirolast has more potent antihyperplastic action than does tranilast. Antiallergic agents may be effective in preventing restenosis after coronary angioplasty.