[Effect of tranilast, an anti-allergic drug, on carrageenin-induced granulation and capillary permeability in rats]

The Most Current Algorithms for the Treatment and Prevention of Hypertrophic Scars and Keloids: A 2020 Update of the Algorithms Published 10 Years Ago

BACKGROUND

In 2010, this Journal published my comprehensive review of the literature on hypertrophic scars and keloids. In that article, I presented evidence-based algorithms for the prevention and treatment of these refractory pathologic scars. In the ensuing decade, substantial progress has been made in the field, including many new randomized controlled trials. To reflect this, I have updated my review.

METHODS

All studies were evaluated for methodologic quality. Baseline characteristics of patients were extracted along with the interventions and their outcomes. Systematic reviews, meta-analyses, and comprehensive reviews were included if available.

RESULTS

Risk factors that promote hypertrophic scar and keloid growth include local factors (tension on the wound/scar), systemic factors (e.g., hypertension), genetic factors (e.g., single-nucleotide polymorphisms), and lifestyle factors. Treatment of hypertrophic scars depends on scar contracture severity: if severe, surgery is the first choice. If not, conservative therapies are indicated. Keloid treatment depends on whether they are small and single or large and multiple. Small and single keloids can be treated radically by surgery with adjuvant therapy (e.g., radiotherapy) or multimodal conservative therapy. For large and multiple keloids, volume- and number-reducing surgery is a choice. Regardless of the treatment(s), patients should be followed up over the long term. Conservative therapies, including gel sheets, tape fixation, topical and injected external agents, oral agents, and makeup therapy, should be administered on a case-by-case basis.

CONCLUSIONS

Randomized controlled trials on pathologic scar management have increased markedly over the past decade. Although these studies suffer from various limitations, they have greatly improved hypertrophic scar and keloid management. Future high-quality trials are likely to improve the current hypertrophic scar and keloid treatment algorithms further.

Tranilast abrogates cisplatin-induced testicular and epididymal injuries: An insight into its modulatory impact on apoptosis/proliferation

Cisplatin is a chemotherapeutic agent whose therapeutic use is greatly limited by the associated organs' toxicity and particularly, testicular toxicity. Cisplatin-induced testicular damage reported being mediated through mitochondria-mediated apoptosis, inflammation, and oxidative stress. Evidence showed that tranilast (TRN) has the ability to restore the oxidative status and modulate TRAIL/caspase-8 signaling. This led us to hypothesize that TRN could abrogate cisplatin-induced testicular and epididymal injuries via inhibiting oxidative stress and modulating proliferation and TRAIL/caspase-8/cJNK signaling. Cisplatin injection induced oligospermia and abnormalities in testicular and epididymal structure along with impaired oxidative status. TRN administration (100 or 300 mg/kg) for 7 days post-cisplatin injection preserved spermatogenesis and restored testicular and epididymal architecture, but restoration was more so in TRN300 than TRN100. This was in line with the restoration of balanced oxidative status as indicated by the increased total antioxidant capacity, glutathione and superoxide dismutase activity, and the decreased malondialdehyde content in testes (p < 0.05 vs. cisplatin). TRN increased the cell proliferation revealed by the increased expression of proliferating cell nuclear antigen in a dose-dependent manner (p < 0.05 vs. cisplatin) whereas only TRN300 decreased testicular cJNK, TRAIL, and caspase-8 expression (p < 0.05 vs. cisplatin). Moreover, TRN dose-dependently inhibited the pro-inflammatory transcription factor NF-kB and the cytokine TNF-α expressions in testes. In conclusion, TRN300 was more effective than TRN100 in alleviating cisplatin-induced testicular and epididymal injuries and in enhancing spermatogenesis. This curative effect of TRN might be mediated through its antioxidant and anti-inflammatory impacts along with its modulatory impact on cJNK/TRAIL/caspase-8 signaling favoring proliferation rather than apoptosis.

Combination Ointment Containing Solid Tranilast Nanoparticles and Dissolved Sericin Is Efficacious for Treating Skin Wound-Healing Deficits and Redness in Diabetic Rats

We attempted to design a combination ointment containing solid tranilast nanoparticles and dissolved sericin as a wound-healing drug (TS-combination ointment), and evaluated its usefulness as therapy for wound-healing deficits in streptozotocin-induced diabetic rat (STZ rat) using kinetic analyses as an index. Solid tranilast nanoparticles were prepared by bead mill methods with low-substituted methylcellulose; the mean particle size of the tranilast nanoparticles was 70 nm. The ointment was designed to contain the tranilast nanoparticles plus sericin powder and/or Carbopol^® 934. Skin wound healing in STZ rats begins significantly later than in normal rats. Although the skin wound healing rate in STZ rats treated with an ointment containing tranilast nanoparticles was lower than in STZ rats treated with vehicle, the ointment was effective in reducing redness. An ointment containing sericin enhanced the skin-healing rate, but the preventive effect on redness was weak. On the other hand, the combination of tranilast and sericin increased both the skin healing rate and reduction in redness. In conclusion, we have adapted kinetic analyses to skin wound healing in rats, and found these analyses to be useful as an index of wound healing ability by a wound-healing drug. In addition, we show that treatment with the TS-combination ointment enhances the skin wound healing rate and reduces redness. These findings provide information significant to the search for new wound-healing therapies and for the design of wound-healing drugs.

Pleiotropic Effects of Immune Responses Explain Variation in the Prevalence of Fibroproliferative Diseases

Many diseases are differentially distributed among human populations. Differential selection on genetic variants in ancestral environments that coincidentally predispose to disease can be an underlying cause of these unequal prevalence patterns. Selected genes may be pleiotropic, affecting multiple phenotypes and resulting in more than one disease or trait. Patterns of pleiotropy may be helpful in understanding the underlying causes of an array of conditions in a population. For example, several fibroproliferative diseases are more prevalent and severe in populations of sub-Saharan ancestry. We propose that this disparity is due to selection for an enhanced Th2 response that confers resistance to helminthic infections, and concurrently increases susceptibility to fibrosis due to the profibrotic action of Th2 cytokines. Many studies on selection of Th2-related genes for host resistance to helminths have been reported, but the pleiotropic impact of this selection on the distribution of fibrotic disorders has not been explicitly investigated. We discuss the disproportionate occurrence of fibroproliferative diseases in individuals of African ancestry and provide evidence that adaptation of the immune system has shaped the genetic structure of these human populations in ways that alter the distribution of multiple fibroproliferative diseases.

Evaluation of the effect of tranilast on rats with spinal cord injury

BACKGROUND

Glial and fibrotic scars inhibit neural regeneration after spinal cord injury (SCI). N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast) inhibits transforming growth factor β, alleviates allergic reactions, and decreases hypertrophic skin scars. We evaluated its ability to improve motor function and inhibit the spread of tissue damage in rats with SCI.

METHODS

Rats with SCI were divided into groups that received tranilast (30 mg/[kg · day]) by intravenous administration (group IV), tranilast (200mg/[kg · day]) by oral administration (group OR), and saline injections (control). Motor functions were assessed by determining Basso, Beattie, and Bresnahan (BBB) scores and %grip tests for 8 weeks after SCI. Histological evaluation of ionized calcium binding adaptor molecule 1 (Iba1) at 1 week after SCI and glial fibrillary acidic protein (GFAP), fibronectin, and chondroitin sulfate (CS) at week 8 was performed.

RESULTS

Motor function recovery, BBB score, and the %grip test were significantly higher in the tranilast-treated groups than in the control group. At week 1 after SCI, inflammatory-cell invasion was more severe and Iba1 expression was significantly higher in the control group. At week 8, although the number of GFAP-positive cells increased greatly from the impaction site to the proximal and distal sites in the control group, these cells were confined around a cavity in the tranilast-treated groups. GFAP distribution coincided with that of fibronectin. Anti-CS antibody level in the tranilast-treated groups was significantly lower than that in the control group.

CONCLUSIONS

Tranilast inhibits inflammation in the acute phase of SCI and reduces glial and fibrotic scars and could present a new method for treating SCI.

Anti-allergic agent tranilast decreases development of obliterative airway disease in rat model of heterotopic tracheal transplantation

BACKGROUND

Tranilast is an anti-allergic agent known to inhibit the release of histamine, interleukin-1beta, transforming growth factor beta1, and platelet-derived growth factor from various cells and currently is used to treat allergic diseases, keloids, and hypertrophic scars. We evaluated the ability of tranilast to inhibit the development of obliterative airway disease (OAD) in a rat model of heterotopic tracheal transplantation.

METHODS

We transplanted tracheal segments from donor rats (Brown Norway) into subcutaneous pouches in major histocompatibility complex-incompatible recipient rats (Lewis). At Days 21 and 28 after transplantation, we histologically assessed the harvested allografts scored the degree of OAD, on a scale from zero to 4 as previously described, caused by fibroproliferative tissue.

RESULTS

Recipient animals treated orally with 400 mg/kg/day tranilast throughout the experiment showed significantly decreased OAD compared with control animals, with a histologic score of 1.1 +/- 0.4 vs 3.0 +/- 1.3, respectively (mean +/- SD, p=0.007), at Day 21 after transplantation and 2.0 +/- 1.4 vs 3.9 +/- 0.4, respectively (mean +/- SD, p=0.017), at Day 28 after transplantation.

CONCLUSION

These results showed that treatment with tranilast significantly decreased fibroproliferative airway changes associated with allograft rejection in a rat model of tracheal transplantation, suggesting that tranilast may be useful in preventing bronchiolitis obliterans after lung transplantation.

Preventive Effect of Tranilast on Oleic Acid-Induced Lung Injury in Guinea Pigs

Acute respiratory distress syndrome or acute lung injury (ARDS)/(ALI) involve the severe lung injury with pulmonary vascular hyper-permeability and hypoxemia induced by inflammatory reactions. Since ARDS/ALI carries high mortality, the development of new drugs against ARDS/ALI is required. We examined the effect of tranilast, an anti-allergic drug, on vascular hyper-permeability in the lungs and airways, and on hypoxemia, in oleic acid (OA)-induced acute lung injury, an animal model of ARDS/ALI. The increase in pulmonary and airway vascular permeability and the decrease in partial oxygen pressure of arterial blood induced by an intravenous injection of OA were drastically ameliorated by the oral administration of tranilast in a dose-dependent manner. This is the first report to prove that tranilast prevents pulmonary and airway vascular permeability and hypoxemia induced by OA. These results suggest that tranilast may be a candidate drug for the treatment of ARDS/ALI.

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 prevention of postoperative intraperitoneal adhesions by tranilast: N-(3',4'-dimethoxycinnamoyl)anthranilic acid

The development of postoperative intraperitoneal adhesions continues to be a major concern for surgeons. The purpose of this study was to establish a postoperative adhesion model in rats, and to assess the effectiveness of tranilast (N-(3',4'-dimethoxycinnamoyl)anthranilic acid) in preventing postoperative adhesion formation. The adhesion model was established in 12 male Donryu rats. This involved two essential factors, drying and bleeding. Another 22 male Donryu rats were used to study the prevention of intraperitoneal adhesions. Tranilast was administered orally pre- and postoperatively. Adhesion strength was evaluated by grading, and basic fibroblast growth factor (bFGF) and transforming growth factor-beta-1 (TGF-beta1) concentration were measured. Postoperative intraperitoneal adhesions were seen in all rats, but the adhesions in the tranilast group were significantly less severe than those in the control group. Serum bFGF and TGF-beta1 levels in the tranilast group were lower at the time of surgery than those in the control group, and bFGF levels were lower at the endpoint of this study in the tranilast group than in the control group. The TGF-beta1 levels at the end-point did not differ between the two groups. These findings demonstrated that tranilast significantly reduced postoperative intraperitoneal adhesion formation.

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.

Tranilast suppresses the vascular intimal hyperplasia after balloon injury in rabbits fed on a high-cholesterol diet

Intimal hyperplasia is a serious problem after percutaneous transluminal coronary angioplasty. In this study, we assessed the effect of tranilast on vascular intimal hyperplasia after balloon injury in rabbits fed on a high-cholesterol diet. In this animal model, intimal hyperplasia more severe than that in rabbits fed on a normal diet was observed. In addition, medial thickening and lipid deposits in both media and intima were also noted. These findings indicate that balloon injury caused intimal and medial hyperplasia and that this hyperplasia was accelerated by the high cholesterol load. Tranilast (300 mg/kg) significantly decreased the intimal area, medial area, and stenosis ratio, and increased the luminal/total area ratio, in the cholesterol-fed rabbits. These results suggest that tranilast may be useful for prevention of restenosis after percutaneous transluminal coronary angioplasty of patients, including those with a clinical risk of hypercholesterolemia.

A chemiluminescent detection of superoxide radical produced by adherent leucocytes to the subendothelium following thrombolysis: studies with a photochemically induced thrombosis model in the guinea pig femoral artery

Reocclusion following thrombolysis is a major limitation of thrombolytic therapy with recombinant tissue-type plasminogen activator (rt-PA) because denuded vessel wall exposed to blood following thrombolysis is a favourable surface for platelet and leucocyte deposition. We have applied a chemiluminescence technique to detect superoxide radical (0(-2)) produced by leucocytes adherent to the femoral artery 24 h after photochemically induced thrombogenesis in the guinea pig in vivo and subsequent thrombolysis by rt-PA. Intravenous administration of MCLA, a specific chemiluminescence reagent for detecting O(-2), markedly increased photon emission. the photon emission was markedly potentiated by phorbol myristate acetate and was suppressed by superoxide dismutase. Reocclusion 24 h after rt-PA induced thrombolysis was observed in 10 of 16 animals. Histological observations revealed extensive polymorphonuclear leucocytes adherent to the vessel wall at the site of thrombogenesis and thrombolysis. A higher level of 0(-2) could be detected from the arteries in which thrombolysis was induced compared with those without thrombolysis. Further, the level 0(-2) detected was greater in reoccluded arteries compared with those in which reflow was established. These observations suggest that 0(-2) is produced by adherent leucocytes at the site of thrombolysis and that leucocytes are involved in reocclusion after thrombolysis.

Tranilast suppresses intimal hyperplasia in the balloon injury model and cuff treatment model in rabbits

Intimal hyperplasia is a serious problem after percutaneous transluminal coronary angioplasty (PTCA). In this study, we investigated the effects of tranilast on intimal hyperplasia in both in vivo and in vitro experiments. For the in vivo experiments, we used the balloon injury model and the cuff treatment model of rabbits fed regular chow. In the balloon injury model, tranilast decreased intimal area, intima/media ratio, stenosis ratio and vascular DNA content after endothelial injury. Also in the cuff treatment model, tranilast suppressed the intimal hyperplasia. In the in vitro experiments, we assessed the effects of tranilast on platelet-derived growth factor-induced rabbit vascular smooth muscle cell (VSMC) migration and proliferation and on collagen synthesis by VSMCs. Tranilast inhibited VSMC migration, proliferation and collagen synthesis. These results suggest that tranilast has a suppressive effect on intimal hyperplasia after a vascular injury such as PTCA.

Tranilast suppresses intimal hyperplasia after photochemically induced endothelial injury in the rat

Intimal thickening in the femoral artery of spontaneously hypertensive rats (SHR) was initiated by endothelial damage induced by the photochemical reaction between green light and systemic rose bengal. This model represents a non-mechanical method of producing vessel wall denudation. Neointima formation was assessed by calculating the cross-sectional area of intima, media and lumen, using computer analysis. Tranilast (30, 100 and 300 mg/kg, p.o.), administered 2 days prior to endothelial injury, reduced intimal area by 29, 62 and 87%, respectively, compared to that of vehicle-treated controls. In cultured SHR-derived vascular smooth muscle cells, tranilast produced concentration-dependent inhibition of mitogenesis, whether stimulated by platelet-derived growth factor, basic fibroblast growth factor, insulin-like growth factor or fetal bovine serum. These results suggest that tranilast may be effective in preventing coronary restenosis.