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

Recent advances in pharmacological treatments of proliferative vitreoretinopathy

PURPOSE OF REVIEW

Proliferative vitreoretinopathy (PVR) is a severe complication of retinal detachment and trauma, posing significant challenges to surgical success and visual prognosis. Despite advancements in vitreoretinal surgery, PVR incidence remains unchanged, this review presents a synthesis of the principal clinical and preclinical research findings from recent years.

RECENT FINDINGS

Recent research has focused on anti-inflammatory, antiproliferative, and antifibrotic agents. Corticosteroids, such as triamcinolone and dexamethasone, show promise in reducing inflammation but have inconsistent results. Methotrexate and mitomycin C demonstrate efficacy in preclinical and select clinical scenarios. Anti-vascular endothelial growth factor agents and immunotherapies, like infliximab, have shown limited clinical benefits despite promising preclinical data. Novel approaches, including CB2 receptor agonists, exosome-based drug delivery, and nuclear factor kappa B pathway inhibitors, are gaining traction. Additionally, RNA-based and multitargeted therapies highlight the importance of addressing inflammation, fibrosis, and proliferation simultaneously.

SUMMARY

Effective management of PVR requires multifaceted therapies targeting its complex pathogenesis. While current treatments are limited, ongoing research in precision drug delivery and combination therapies offers hope for improved outcomes. Future strategies should focus on translating promising preclinical findings into robust clinical applications.

Unlocking the potential of tranilast: Targeting fibrotic signaling pathways for therapeutic benefit

Fibrosis is the excessive deposition of extracellular matrix in an organ or tissue that results from an impaired tissue repair in response to tissue injury or chronic inflammation. The progressive nature of fibrotic diseases and limited treatment options represent significant healthcare challenges. Despite the substantial progress in understanding the mechanisms of fibrosis, a gap persists translating this knowledge into effective therapeutics. Here, we discuss the critical mediators involved in fibrosis and the role of tranilast as a potential antifibrotic drug to treat fibrotic conditions. Tranilast, an antiallergy drug, is a derivative of tryptophan and has been studied for its role in various fibrotic diseases. These include scleroderma, keloid and hypertrophic scars, liver fibrosis, renal fibrosis, cardiac fibrosis, pulmonary fibrosis, and uterine fibroids. Tranilast exerts antifibrotic effects by suppressing fibrotic pathways, including TGF-β, and MPAK. Because it disrupts fibrotic pathways and has demonstrated beneficial effects against keloid and hypertrophic scars, tranilast could be used to treat other conditions characterized by fibrosis.

Kynurenines as a Novel Target for the Treatment of Inflammatory Disorders

This review discusses the potential of targeting the kynurenine pathway (KP) in the treatment of inflammatory diseases. The KP, responsible for the catabolism of the amino acid tryptophan (TRP), produces metabolites that regulate various physiological processes, including inflammation, cell cycle, and neurotransmission. These metabolites, although necessary to maintain immune balance, may accumulate excessively during inflammation, leading to systemic disorders. Key KP enzymes such as indoleamine 2,3-dioxygenase 1 (IDO1), indoleamine 2,3-dioxygenase 2 (IDO2), tryptophan 2,3-dioxygenase (TDO), and kynurenine 3-monooxygenase (KMO) have been considered promising therapeutic targets. It was highlighted that both inhibition and activation of these enzymes may be beneficial, depending on the specific inflammatory disorder. Several inflammatory conditions, including autoimmune diseases, for which modulation of KP activity holds therapeutic promise, have been described in detail. Preclinical studies suggest that this modulation may be an effective treatment strategy for diseases for which treatment options are currently limited. Taken together, this review highlights the importance of further research on the clinical application of KP enzyme modulation in the development of new therapeutic strategies for inflammatory diseases.

Therapeutic Effects of Long-Term Administration of Tranilast in an Animal Model for the Treatment of Fibroids

Tranilast (N-3, 4-dimethoxycinnamoyl anthranilic acid) is an orally administered drug with antiallergic properties and approved in Japan and the Republic of Korea for the treatment of asthma and hypertrophic scars. Previous in vitro studies indicated that tranilast reduced fibroid growth through its inhibitory effects on cell proliferation and induction of apoptosis. The objective of this study was to determine the efficacy of tranilast for treatment of human-derived fibroids in a mouse model. SCID mice (ovariectomized, supplemented with estrogen and progesterone) were implanted with fibroid explants and treated for two months with tranilast (50 m/kg/daily) or the vehicle. After sacrifice, xenografts were excised and analyzed. Tranilast was well tolerated without adverse side effects. There was a 37% reduction in tumor weight along with a significant decrease in staining for Ki67, CCND1, and E2F1; a significant increase in nuclear staining for cleaved caspase 3; and reduced staining for TGF-β3 and Masson's trichrome in the tranilast treated mice. There was a significant inhibition of mRNA and protein expression of fibronectin, COL3A1, CCND1, E2F1, and TGF-β3 in the xenografts from the tranilast-treated mice. These promising therapeutic effects of tranilast warrant additional animal studies and human clinical trials to evaluate its efficacy for treatment of fibroids.

The NLRP3 Inflammasome Pathway: A Review of Mechanisms and Inhibitors for the Treatment of Inflammatory Diseases

The NLRP3 inflammasome is a multiprotein complex that plays a pivotal role in regulating the innate immune system and inflammatory signaling. Upon activation by PAMPs and DAMPs, NLRP3 oligomerizes and activates caspase-1 which initiates the processing and release of pro-inflammatory cytokines IL-1β and IL-18. NLRP3 is the most extensively studied inflammasome to date due to its array of activators and aberrant activation in several inflammatory diseases. Studies using small molecules and biologics targeting the NLRP3 inflammasome pathway have shown positive outcomes in treating various disease pathologies by blocking chronic inflammation. In this review, we discuss the recent advances in understanding the NLRP3 mechanism, its role in disease pathology, and provide a broad review of therapeutics discovered to target the NLRP3 pathway and their challenges.

The key role of organic anion transporter 3 in the drug-drug interaction between tranilast and methotrexate

Tranilast, N-(3',4'-dimethoxycinnamoyl)-anthranilic acid, is an anti-allergic drug and is considered for use in the treatment of rheumatoid arthritis. Methotrexate, an antimetabolite and folate antagonist to treat some cancers, is also a first-line drug for RA. The aim of this study was to understand whether tranilast could inhibit renal uptake transporters (Oat1, Oat3, and Oct2) and whether MTX combined with TL would have drug-drug interactions. The results of kidney slices and HEK293T-OAT3 cell uptake experiments showed that TL (10 μM) could inhibit the uptake of penicillin G and MTX, which are substrates of OAT3. When TL (10 mg/kg) was combined with MTX (5 mg/kg), the area under the curve and peak concentration of MTX increased by 46.46% and 113.51%, respectively, while the pharmacokinetic process of tranilast (10 mg/kg) was not changed by methotrexate (5 mg/kg). TL could increase plasma exposure of MTX by inhibiting Oat3 in vitro and in vivo.

Tranilast: a potential anti-Inflammatory and NLRP3 inflammasome inhibitor drug for COVID-19

SARS-CoV-2 is a type of beta-CoV that develops acute pneumonia, which is an inflammatory condition. A cytokine storm has been recognized as one of the leading causes of death in patients with COVID-19. ALI and ARDS along with multiple organ failure have also been presented as the consequences of acute inflammation and cytokine storm. It has been previously confirmed that SARS-CoV, as another member of the beta-CoV family, activates NLRP3 inflammasome and consequently develops acute inflammation in a variety of ways through having complex interactions with the host immune system using structural and nonstructural proteins. Numerous studies conducted on Tranilast have further demonstrated that the given drug can act as an effective anti-chemotactic factor on controlling inflammation, and thus, it can possibly help the improvement of the acute form of COVID-19 by inhibiting some key inflammation-associated transcription factors such as NF-κB and impeding NLRP3 inflammasome. Several studies have comparably revealed the direct effect of this drug on the prevention of inappropriate tissue's remodeling; inhibition of neutrophils, IL-5, and eosinophils; repression of inflammatory cell infiltration into inflammation site; restriction of factors involved in acute airway inflammation like IL-33; and suppression of cytokine IL-13, which increase mucosal secretions. Therefore, Tranilast may be considered as a potential treatment for patients with the acute form of COVID-19 along with other drugs.

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.

Inflammation, immunity and potential target therapy of SARS-COV-2: A total scale analysis review

Coronavirus disease-19 (COVID-19) is a complex disease that causes illness ranging from mild to severe respiratory problems. It is caused by a novel coronavirus SARS-CoV-2 (Severe acute respiratory syndrome coronavirus-2) that is an enveloped positive-sense single-stranded RNA (+ssRNA) virus belongs to coronavirus CoV family. It has a fast-spreading potential worldwide, which leads to high mortality regardless of lows death rates. Now some vaccines or a specific drug are approved but not available for every country for disease prevention and/or treatment. Therefore, it is a high demand to identify the known drugs and test them as a possible therapeutic approach. In this critical situation, one or more of these drugs may represent the only option to treat or reduce the severity of the disease, until some specific drugs or vaccines will be developed and/or approved for everyone in this pandemic. In this updated review, the available repurpose immunotherapeutic treatment strategies are highlighted, elucidating the crosstalk between the immune system and SARS-CoV-2. Despite the reasonable data availability, the effectiveness and safety of these drugs against SARS-CoV-2 needs further studies and validations aiming for a better clinical outcome.

Tranilast induces MiR-200c expression through blockade of RelA/p65 activity in leiomyoma smooth muscle cells

OBJECTIVE

To determine the mechanism by which tranilast induces miR-200c expression in leiomyoma smooth muscle cells (LSMCs).

DESIGN

Experimental study.

SETTING

Academic research laboratory.

PATIENT(S)

Women undergoing hysterectomy for leiomyoma.

INTERVENTION(S)

Blockade of RelA/p65.

MAIN OUTCOME MEASURE(S)

Effects of tranilast and blockade of RelA/p65 on miR-200c expression.

RESULT(S)

Tranilast, an inflammation inhibitor, dose-dependently induced miR-200c in LSMCs and myometrium smooth muscle cells (MSMCs), with a more profound effect in LSMCs than in MSMCs. The treatment of LSMCs with Bay 117082, an inhibitor of IκB phosphorylation, further enhanced miR-200c induction by tranilast. The knockdown of RelA/p65 by small interfering RNA also induced miR-200c expression in LSMCs. Although tranilast had no effect on total RelA/p65 protein levels in LSMCs, it significantly induced RelA/p65 phosphorylation at S536 while reducing its activity as well as its nuclear translocation. ChIP assay indicated that tranilast reduces the binding ability of RelA/p65 to miR-200c promoter, resulting in miR-200c induction. Tranilast also inhibited interleukin-8 (IL8) expression in LSMCs. The induction of miR-200c by tranilast partially mediates the inhibitory effect of tranilast on the expression of IL8 and cyclin-dependent kinase 2 in LSMCs.

CONCLUSION(S)

Induction of miR-200c by tranilast in LSMCs is mediated through a transcriptional mechanism involving inhibition of the nuclear factor κB signaling pathway. These results highlight the significance of inflammation in the pathogenesis of leiomyoma and the potential utility of antiinflammatory drugs for treatment of leiomyomas.

Repurposing of Tranilast for Potential Neuropathic Pain Treatment by Inhibition of Sepiapterin Reductase in the BH4 Pathway

Tetrahydrobiopterin (BH₄) is a cofactor in the production of various signaling molecules including nitric oxide, dopamine, adrenaline, and noradrenaline. BH₄ levels are critical for processes associated with cardiovascular function, inflammation, mood, pain, and neurotransmission. Increasing pieces of evidence suggest that BH₄ is upregulated in chronic pain. Sepiapterin reductase (SPR) catalyzes both the reversible reduction of sepiapterin to dihydrobiopterin (BH₂) and 6-pyruvoyl-tetrahydrobiopterin to BH₄ within the BH₄ pathway. Therefore, inhibition of SPR by small molecules can be used to control BH₄ production and ultimately alleviate chronic pain. Here, we have used various in silico and in vitro experiments to show that tranilast, licensed for use in bronchial asthma, can inhibit sepiapterin reduction by SPR. Docking and molecular dynamics simulations suggest that tranilast can bind to human SPR (hSPR) at the same site as sepiapterin including S157, one of the catalytic triad residues of hSPR. Colorimetric assays revealed that tranilast was nearly twice as potent as the known hSPR inhibitor, N-acetyl serotonin. Tranilast was able to inhibit hSPR activity both intracellularly and extracellularly in live cells. Triple quad mass spectrophotometry of cell lysates showed a proportional decrease of BH₄ in cells treated with tranilast. Our results suggest that tranilast can act as a potent hSPR inhibitor and therefore is a valid candidate for drug repurposing in the treatment of chronic pain.

Tranilast directly targets NLRP3 to treat inflammasome-driven diseases

The dysregulation of NLRP3 inflammasome can cause uncontrolled inflammation and drive the development of a wide variety of human diseases, but the medications targeting NLRP3 inflammasome are not available in clinic. Here, we show that tranilast (TR), an old anti‐allergic clinical drug, is a direct NLRP3 inhibitor. TR inhibits NLRP3 inflammasome activation in macrophages, but has no effects on AIM2 or NLRC4 inflammasome activation. Mechanismly, TR directly binds to the NACHT domain of NLRP3 and suppresses the assembly of NLRP3 inflammasome by blocking NLRP3 oligomerization. In vivo experiments show that TR has remarkable preventive or therapeutic effects on the mouse models of NLRP3 inflammasome‐related human diseases, including gouty arthritis, cryopyrin‐associated autoinflammatory syndromes, and type 2 diabetes. Furthermore, TR is active ex vivo for synovial fluid mononuclear cells from patients with gout. Thus, our study identifies the old drug TR as a direct NLRP3 inhibitor and provides a potentially practical pharmacological approach for treating NLRP3‐driven diseases.

Therapeutic potential of tranilast for the treatment of chronic graft-versus-host disease in mice

Chronic graft-versus-host disease (cGVHD) is a marked complication of hematopoietic stem cell transplantation, and multiple organs can be affected by cGVHD-induced inflammation and fibrosis. In clinical settings, immunosuppressive agents have been the last resort to treat cGVHD. However, it has been only partially effective for cGVHD. Hence, efficacious treatment of cGVHD is eagerly awaited. Our previous work suggested that oxidative stress was elevated in cGVHD-disordered lacrimal glands and that epithelial-to-mesenchymal transition (EMT) was implicated in fibrosis caused by ocular cGVHD. In addition, our recent article demonstrated that thioredoxin interaction protein (TXNIP) and transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-𝛋B) were associated with the development of cGVHD. After our search for effective drugs, we chose tranilast to combat systemic cGVHD. Tranilast is known to (1) act as an inhibitor of the inflammatory molecules TXNIP and NF-κB and (2) exert anti-fibrotic, anti-EMT and anti-oxidative effects. To investigate the effectiveness of tranilast for cGVHD, we used an MHC-compatible, multiple minor histocompatibility antigen-mismatched murine model of cGVHD. Tranilast or a solvent-vehicle were orally given to the allogeneic bone marrow transplantation (allo-BMT) recipients from the day before allo-BMT (Day-1) to Day 27 after allo-BMT. Their cGVHD-vulnerable organs were collected Day 28 after allo-BMT and analyzed by using various methods such as histology, immunohistochemistry and immunoblotting. As indicated by our results, tranilast alleviated cGVHD-elicited inflammation and fibrosis by suppressing the expression and/or activation of TXNIP and NF-κB and preventing EMT. Taken together, although this strategy may not be a complete cure for cGVHD, tranilast could be a promising medication to ameliorate cGVHD-triggered disabling symptoms.

Biological Activities, Health Benefits, and Therapeutic Properties of Avenanthramides: From Skin Protection to Prevention and Treatment of Cerebrovascular Diseases

Oat (Avena sativa) is a cereal known since antiquity as a useful grain with abundant nutritional and health benefits. It contains distinct molecular components with high antioxidant activity, such as tocopherols, tocotrienols, and flavanoids. In addition, it is a unique source of avenanthramides, phenolic amides containing anthranilic acid and hydroxycinnamic acid moieties, and endowed with major beneficial health properties because of their antioxidant, anti-inflammatory, and antiproliferative effects. In this review, we report on the biological activities of avenanthramides and their derivatives, including analogs produced in recombinant yeast, with a major focus on the therapeutic potential of these secondary metabolites in the treatment of aging-related human diseases. Moreover, we also present recent advances pointing to avenanthramides as interesting therapeutic candidates for the treatment of cerebral cavernous malformation (CCM) disease, a major cerebrovascular disorder affecting up to 0.5% of the human population. Finally, we highlight the potential of foodomics and redox proteomics approaches in outlining distinctive molecular pathways and redox protein modifications associated with avenanthramide bioactivities in promoting human health and contrasting the onset and progression of various pathologies. The paper is dedicated to the memory of Adelia Frison.

High Levels of Avenanthramides in Oat-Based Diet Further Suppress High Fat Diet-Induced Atherosclerosis in Ldlr-/- Mice

Oats, in addition to cholesterol-lowering properties, contain unique antioxidants called avenanthramides (Avns), which inhibit both inflammatory cytokines and adhesion molecules in endothelial cells in culture. This study evaluated the effects of Avns of oats on atherosclerosis in Ldlr^-/- mice, one of the most commonly used atherosclerosis mouse models with their similar cholesterol distributions to humans. The Ldlr^-/- mice were fed a low fat, high fat, high fat containing regular oat brans with low levels of Avns (HFLA), or high fat containing regular oat brans with high levels of Avns (HFHA) diet. After 16 weeks of intervention, blood cholesterol and extent of aortic lesions were evaluated. We found that both oat-based diets reduced high fat diet-induced atheroma lesions in the aortic valve (p < 0.01). Furthermore, the effects of oat-based diets are more profound in HFHA mice than mice fed HFLA. Total plasma cholesterol levels were similarly reduced in both oat-supplemented mice. We concluded that oat bran diets reduce atheroma lesions and higher levels of Avns further reduce aortic lesions compared to regular oat bran. These preliminary in vivo data indicate that consumption of oats bran, with high Avns, has demonstrable beneficial effects on prevention of cardiovascular disease.

The Histone Deacetylase Inhibitor Valproic Acid Sensitizes Gemcitabine-Induced Cytotoxicity in Gemcitabine-Resistant Pancreatic Cancer Cells Possibly Through Inhibition of the DNA Repair Protein Gamma-H2AX

BACKGROUND

Gemcitabine (GEM) remains a major chemotherapeutic drug for pancreatic cancer, but resistance to GEM has been a big problem, as its response rate has been decreasing year by year.

METHODS

The effect of the histone deacetylase inhibitor (HDAI) valproic acid (VPA) was compared with tranilast and RI-1 as a combinatorial treatment with GEM in four pancreatic cancer cell lines, BxPC-3, PK45p, MiaPaCa-2 and PK59. Cell viability assays were carried out to check the cytotoxic effects, western blotting was carried out for DNA repair mechanisms, and localization was determined by immunofluorescence.

RESULTS

The sensitization factors (i.e., the fold ratio of cell viability for GEM/GEM plus drug) reveal that VPA increases the cytotoxic sensitization to GEM at approximately 2.7-fold, 1.2-fold, 1.5-fold and 2.2-fold in BxPC-3, MiaPaCa-2, PK-45p and PK-59 cell lines, respectively. Moreover, GEM induces activation of the DNA repair protein H2AX proportional to the dosage. Interestingly, however, this effect can be abrogated by VPA.

CONCLUSIONS

These results indicate that VPA enhances GEM-induced cytotoxicity in GEM-resistant pancreatic cancer cells, possibly through inhibition of DNA damage signaling and repair. Our study suggests VPA as a potential therapeutic agent for combinatorial treatment with GEM in pancreatic cancer.

Effective treatment for prevention of post-operative adhesion after strabismus surgery in experimental rabbit model: 0.5 % tranilast ophthalmic solution

Background

Postoperative adhesion is one of the major complications of strabismus surgery and result in motility dysfunction that brings unpredictable surgical outcomes. However, there was no definitely accepted treatment method to prevent postoperative adhesion.

Methods

A prospective, randomized, controlled experimental animal study was performed. Both eyes of each of 14 New Zealand White rabbits underwent superior rectus muscle recession. After the surgical procedure, the subjects were divided randomly into two groups; 0.5 % tranilast ophthalmic solutions and fluoroquinolone antibiotic eye drops were administered to the group tranilast (N = 14), while the group control (N = 14) received fluoroquinolone eye drops only. Five weeks after surgery, we evaluated gross adhesions with a numeric score (0 to 4). In addition, histopathologic examination with hematoxylin & eosin staining, Masson’s-trichrome staining, and anti-transforming growth factor beta 1 (TGF-β1) immuno-histochemical staining were done.

Results

The group tranilast showed significantly less gross adhesion and inflammation than the group control (P = 0.01 and P < 0.001, respectively). Masson’s-trichrome staining revealed that post-operative collagen deposition was more prominent in the group control than the group tranilast (P < 0.001). Moreover, remarkable TGF-β1 expression was observed in areas with excessive collagen deposition.

Conclusions

Instillation of 0.5 % tranilast ophthalmic solution is a simple and effective method for preventing post-operative adhesion after strabismus surgery.

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.

Inhibitory Effects of Tranilast on Cytokine, Chemokine, Adhesion Molecule, and Matrix Metalloproteinase Expression in Human Corneal Fibroblasts Exposed to Poly(I:C)

Purpose/Aim: Viral infection of the cornea can result in inflammation and scarring and eventually cause blindness. Polyinosinic-polycytidylic acid [poly(I:C)], an analog of viral double-stranded RNA, induces the synthesis of various cytokines, chemokines, adhesion molecules, and matrix metalloproteinases (MMPs) in corneal fibroblasts. The effects of tranilast on the expression of these molecules in human corneal fibroblasts were examined.

MATERIALS AND METHODS

Human corneal fibroblasts were cultured with or without poly(I:C) or tranilast. The release of the proinflammatory cytokine interleukin (IL)-6 and of the chemokines IL-8 and monocyte chemotactic protein-1 (MCP-1) was measured with enzyme-linked immunosorbent assays. The expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), MMP-1, and MMP-3 was evaluated by immunoblot or immunofluorescence analysis. The phosphorylation of mitogen-activated protein kinases (MAPKs), c-Jun (a component of the transcription factor AP-1), and IκB-α (an endogenous inhibitor of the transcription factor NF-κB) was examined by immunoblot analysis.

RESULTS

Tranilast inhibited in a concentration- and time-dependent manner the production of IL-6, IL-8, MCP-1, ICAM-1, VCAM-1, MMP-1, and MMP-3 by corneal fibroblasts exposed to poly(I:C). It also inhibited the poly(I:C)-induced phosphorylation of c-Jun and the MAPK JNK without affecting that of IκB-α or the MAPKs ERK and p38.

CONCLUSIONS

Tranilast inhibited proinflammatory cytokine, chemokine, adhesion molecule, and MMP expression in human corneal fibroblasts exposed to poly(I:C), with these effects likely being mediated by attenuation of JNK-AP-1 signaling. Tranilast might therefore be expected to limit immune cell infiltration and stromal degradation associated with viral infection of the cornea.

Tranilast reduces serum IL-6 and IL-13 and protects against thioacetamide-induced acute liver injury and hepatic encephalopathy

Hepatic encephalopathy is a serious neuropsychiatric disorder usually affecting either acute or chronic hepatic failure patients. Hepatic encephalopathy was replicated in a validated rat model to assess the potential protective efficacy of tranilast against experimentally induced hepatic encephalopathy. Thioacetamide injection significantly impaired hepatic synthetic, metabolic and excretory functions with significant increase in serum NO, IL-6 and IL-13 levels and negative shift in the oxidant/antioxidant balance. Most importantly, there was a significant increase in serum ammonia levels with significant astrocytes' swelling and vacuolization; hallmarks of hepatic encephalopathy. Tranilast administration (300 mg/kg, orally) for 15 days significantly improved hepatic functions, restored oxidant/antioxidant balance, reduced serum NO, IL-6 and IL-13 levels. Meanwhile, serum ammonia significantly declined with significant reduction in astrocytes' swelling and vacuolization. Several mechanisms can be implicated in the observed hepato- and neuroprotective potentials of tranilast, such as its anti-inflammatory potential, its antioxidant potential as well as its immunomodulatory properties.

HIPK2 is a new drug target for anti-fibrosis therapy in kidney disease

In vitro and animal studies continue to elucidate the mechanisms of fibrosis and have led to advancements in treatment for idiopathic pulmonary fibrosis and cirrhosis, but the search for treatments for renal fibrosis has been more disappointing. Here, we will discuss homeodomain-interacting-protein kinase 2 (HIPK2), a novel regulator of fibrosis that acts upstream of major fibrosis signaling pathways. Its key role in renal fibrosis has been validated in vitro and in several murine models of chronic kidney diseases (CKD).

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.

Protection against ovariectomy-induced bone loss by tranilast

Background

Tranilast (N-(3′,4′-dimethoxycinnamonyl) anthranilic acid) has been shown to be therapeutically effective, exerting anti-inflammatory and anti-oxidative effects via acting on macrophage. We hypothesized that Tranilast may protect against oxidative stress-induced bone loss via action in osteoclasts (OCs) that shares precursors with macrophage.

Methodology and Principal Findings

To elucidate the role of Tranilast, ovariectomy (OVX)-induced bone loss in vivo and OC differentiation in vitro were evaluated by µCT and tartrate-resistant acid phosphatase staining, respectively. Oral administration of Tranilast protected against OVX-induced bone loss with decreased serum level of reactive oxygen species (ROS) in mice. Tranilast inhibited OC formation in vitro. Decreased osteoclastogenesis by Tranilast was due to a defect of receptor activator of nuclear factor-κB ligand (RANKL) signaling, at least partly via decreased activation of nuclear factor-κB and reduced induction and nuclear translocation of nuclear factor of activated T cells, cytoplasmic 1 (or NFAT2). Tranilast also decreased RANKL-induced a long lasting ROS level as well as TGF-β to inhibit osteoclastogenesis. Reduced ROS caused by Tranilast was due to the induction of ROS scavenging enzymes (peroxiredoxin 1, heme oxygenase-1, and glutathione peroxidase 1) as well as impaired ROS generation.

Conclusions/Significance

Our data suggests the therapeutic potential of Tranilast for amelioration of bone loss and oxidative stress due to loss of ovarian function.

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.

The role of transforming growth factor β in glaucoma and the therapeutic implications

Glaucoma is a progressive optic neuropathy frequently associated with elevated intraocular pressure, ocular vascular changes and extracellular matrix remodelling at the optic nerve head and in the trabecular meshwork. The pathogenesis is multifactorial and complex, but many recent studies have suggested that transforming growth factor-β (TGF-β) plays a major role in the process. Significantly elevated levels of TGF-β have been identified in the anterior chamber of glaucomatous eyes. TGF-β has also been shown to directly cause increased intraocular pressure. It is believed that this occurs through complex interaction with the trabecular meshwork, leading to decreased aqueous humour outflow. These processes occur through specific interactions with various proteins and signalling molecules also present in ocular tissues. By understanding the role that TGF-β plays in the pathogenesis of glaucoma, alternative therapeutic agents can be developed, which target these pathways and improve and assist in the management of disease. This review will cover previous investigative studies and discuss the current understanding of TGF-β's role in glaucoma and how it may serve as a potential therapeutic target.

A pilot study of scheduled endoscopic balloon dilation with oral agent tranilast to improve the efficacy of stricture dilation after endoscopic submucosal dissection of the esophagus

BACKGROUNDS AND AIM

As circumferential or near-circumferential endoscopic submucosal dissection (ESD) for superficial esophageal neoplasms might evoke refractory strictures, multiple sessions of endoscopic balloon dilation (EBD) are required. We aimed to assess the effectiveness and safety of oral agent tranilast with EBD for improving the efficacy of stricture dilation after esophageal ESD.

METHODS

In an open-label prospective study at a single institution, 31 asymptomatic consecutive patients with superficial esophageal squamous cell carcinomas were enrolled from April 2007 to October 2010. After ESD, we performed scheduled EBD (twice weekly for 4 wk) with or without administration of oral agent tranilast for 8 weeks. Thereafter, we added additional EBD on the basis of solid criteria-for example, patient's awareness of vomiting >1/wk and inability of passage of routine endoscope through the ESD site. We compared the rates of post-ESD strictures and the numbers of additional EBD sessions for 48 weeks after ESD and the Dysphagia score between tranilast (T)-group and none (N)-group, based on patients' subjective symptoms, at 16, 24, and 48 weeks after ESD.

RESULTS

The percentage of post-ESD strictures in T-group was significantly lower than that in N-group (P=0.04). The median numbers of additional EBD sessions and Dysphagia score at 16 and 24 weeks after ESD in T-group were significantly smaller than those in N-group (P=0.0138, 0.002, 0.005, respectively). No adverse events and no recurrence were observed.

CONCLUSIONS

We demonstrated for the first time that scheduled EBD combined with oral agent tranilast might be effective and safe for improving the efficacy of stricture dilation after esophageal ESD.

Neuropilin-1 is expressed by breast cancer stem-like cells and is linked to NF-κB activation and tumor sphere formation

Cancer stem cells (CSCs) initiate tumors and have a high resistance to conventional cancer therapy. Tranilast is an orally active drug of low toxicity that exerts inhibitory effects on breast CSCs. This appears to depend on its aryl hydrocarbon receptor (AHR) agonistic activity, but this receptor has diverse functions and it is unclear how CSCs are inhibited. CSCs generate tumor spheres in low-adherence cultures, and we employed the mammosphere-forming assay as a functional test for breast CSCs. Because NF-κB has a key role in mammosphere formation and CSC-mediated tumor initiation, we examined that pathway. We also examined the role of neuropilin-1 (Nrp1), which is a growth factor coreceptor linked to the tumorigenicity of some CSCs. We found that tranilast concurrently suppressed mammosphere formation, Nrp1 expression and constitutive NF-κB activation. Flow cytometric analysis revealed that a subpopulation of breast cancer cells bearing breast CSC markers also expressed Nrp1. A blocking anti-Nrp1 antibody suppressed mammosphere formation. We examined whether there was a link between Nrp1 and NF-κB activation. The siRNA knockdown of Nrp1 severely suppressed NF-κB activation and mammosphere formation. The phosphorylation of Akt and ERK1/2 was also reduced, but to a lesser extent. We conclude that Nrp1 plays a key role in mammosphere formation and this activity is linked to NF-κB activation. Thus, Nrp1 might be a target for therapy against breast CSCs, and the anticancer drug tranilast suppresses its expression.

Down-regulation of CREB-binding protein expression blocks thrombin-mediated endothelial activation by inhibiting acetylation of NF-κB

OBJECTIVES

CREB-binding protein (CBP) belongs to a unique class of transcription co-activators possessing histone acetyltransferase (HAT) activity. The aim of the present study was to evaluate the role of CBP in thrombin-induced endothelial activation, and also explore the underlying mechanism.

METHODS

Leukocyte-endothelial adhesion was calculated as the proportion of the labeled-neutrophils that adhered to ECs relative to all neutrophils applied. Levels of adhesion molecules were analyzed by real-time RT-PCR and western blot. Electrophoretic mobility shift assay and NF-κB reporter assay were performed to evaluate NF-κB activation. Acetylation of NF-κB was measured with immunoprecipitation and western blot assay. To detect the CBP-HAT activity, acetyl residues on an acetylated histone H4 was analyzed.

RESULTS

Leukocyte-endothelial adhesion induced by thrombin was markedly attenuated in endothelial cells with CBP knockdown. The decreased adhesion was paralleled by the reduction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin. Furthermore, CBP silencing suppressed thrombin-mediated NF-κB activation, and this inhibitory effect was associated with decreased acetylation of NF-κB and CBP-HAT activity.

CONCLUSIONS

Our results indicate that CBP is involved in the regulation of endothelial activation via NF-κB-dependent pathway. Down-regulation of CBP may play a role in returning ECs from a pre-inflammatory status to a quiescent state in the pathogenesis of atherosclerosis.

Different roles of mast cells in obesity and diabetes: lessons from experimental animals and humans

Mast cells (MCs) play an important role in allergic hyperresponsiveness and in defending microorganism infections. Recent studies of experimental animals and humans have suggested that MCs participate in obesity and diabetes. MC distribution and activities in adipose tissues may vary, depending on the locations of different adipose tissues. In addition to releasing inflammatory mediators to affect adipose tissue extracellular matrix remodeling and to promote inflammatory cell recruitment and proliferation, MCs directly and indirectly interact and activate adipose tissue cells, including adipocytes and recruited inflammatory cells. Plasma MC protease levels are significantly higher in obese patients than in lean subjects. Experimental obese animals lose body weight after MC inactivation. MC functions in diabetes are even more complicated, and depend on the type of diabetes and on different diabetic complications. Both plasma MC proteases and MC activation essential immunoglobulin E levels are significant risk factors for human pre-diabetes and diabetes mellitus. MC stabilization prevents diet-induced diabetes and improves pre-established diabetes in experimental animals. MC depletion or inactivation can improve diet-induced type 2 diabetes and some forms of type 1 diabetes, but also can worsen other forms of type 1 diabetes, at least in experimental animals. Observations from animal and human studies have suggested beneficial effects of treating diabetic patients with MC stabilizers. Some diabetic patients may benefit from enhancing MC survival and proliferation – hypotheses that merit detailed basic researches and clinical studies.

Andrographolide inhibits ICAM-1 expression and NF-κB activation in TNF-α-treated EA.hy926 cells

Several lines of evidence indicate that inflammation and endothelial cell dysfunction are important initiating events in atherosclerosis. Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine, induces the expression of cell adhesion molecules and results in monocyte adherence and atheromatous plaque formation. Andrographolide (AP) is a major bioactive diterpene lactone in Andrographis paniculata that has anti-inflammatory activity. A previous study demonstrated the role of heme oxygenase 1 (HO-1) in the inhibition of TNF-α-induced ICAM-1 expression by AP. The present study investigated the effect of AP on the IKK/NF-κB signaling pathway, which mediates TNF-α-induced ICAM-1 expression in EA.hy926 cells. Similar to the previous study, AP inhibited TNF-α-induced ICAM-1 mRNA and protein levels, its expression on the cell surface, and subsequent adhesion of HL-60 cells to EA.hy926 cells. AP inhibited TNF-α-induced κB inhibitor (IκB) kinase (IKK) and IκBα activation, p65 nuclear translocation, NF-κB and DNA binding activity, and promoter activity of ICAM-1. Although AP increased the intracellular cAMP concentration and induced the phosphorylation of cAMP response element-binding protein (CREB), knocking down CREB protein expression by transfecting the cells with CREB-specific small interfering RNA did not relieve the inhibition of ICAM-1 expression by AP. Taken together, these results suggest that AP down-regulates TNF-α-induced ICAM-1 expression at least in part via attenuation of activation of NF-κB in EA.hy926 cells rather than through activation of CREB. The results suggest that AP may have potential as a cardiovascular-protective agent.

Tranilast could has potential therapeutic value in the treatment of psoriasis

Psoriasis is a common chronic skin disease characterized by recurrent erythromatous skin plaques that exhibit epidermal hyperplasia, variable inflammatory cell infiltrate, and abnormalities of the dermal vascularization. The involvement of angiogenic growth factors such as vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs) and inflammatory cytokines such as IFNγ, IL-1, IL-2, TNFα, TGFα and β, IL-6, IL-8, amphiregulin and monocyte chemoattractant protein 1 (MCP-1) have been known to play pathogenic roles in traumatic psoriatic skin. However, anti-angiogenic and anti-inflammatory cytokines regimens might favorably affect the psoriasis disease process. Tranilast is an anti-allergic drug now emerging as anti-angiogenesis and anti-inflammatory effects. In vitro and in vivo experiments have also been strongly showed that tranilast would treat skin psoriasis by inhibition of involving factors. Herein, we hypothesize that local administration of tranilast may be potentially clinically useful in psoriasis.

The transcription factor Erg inhibits vascular inflammation by repressing NF-kappaB activation and proinflammatory gene expression in endothelial cells

OBJECTIVE

To test whether ETS-related gene (Erg) inhibits tumor necrosis factor (TNF)-α-dependent endothelial activation and inflammation.

METHODS AND RESULTS

Endothelial activation underlies many vascular diseases, including atherosclerosis. Endothelial activation by proinflammatory cytokines decreases expression of the ETS transcription factor Erg. By using human umbilical vein endothelial cells (HUVECs), we showed that Erg overexpression by adenovirus (AdErg) repressed basal and TNF-α-induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule (VCAM), and interleukin 8 (IL-8). Erg inhibited TNF-α-dependent activation of the ICAM-1 promoter, nuclear factor (NF)-κB activity, and NF-κB p65 phosphorylation. Basal NF-κB activity was also inhibited by Erg overexpression. Chromatin immunoprecipitation showed that Erg binds to the ICAM-1 proximal promoter region, which contains 7 putative ETS binding sites. To test the anti-inflammatory role of Erg in vivo, we used a murine model of TNF-α-dependent acute inflammation. The injection of AdErg into the paw decreased TNF-α-induced inflammation compared with control. Finally, staining of human coronary plaques showed loss of Erg expression from the endothelium overlaying active plaque shoulders.

CONCLUSIONS

We have identified a novel physiological anti-inflammatory pathway under the control of the transcription factor Erg; this pathway inhibits NF-κB-dependent transcription and TNF-α-induced inflammation in vivo. These results suggest a novel approach to anti-inflammatory therapies.

The anti-allergic compound tranilast attenuates inflammation and inhibits bone destruction in collagen-induced arthritis in mice

BACKGROUND AND PURPOSE

Recent findings suggest the importance of mast cells in the pathogenesis of rheumatoid arthritis and their potential as a therapeutic target. Tranilast is an anti-allergic compound with a potent membrane-stabilizing effect on mast cells and a wide range of anti-inflammatory effects, thus may be advantageous in the treatment of arthritis. Here, we have evaluated the effects of tranilast on the progression of collagen-induced arthritis in mice.

EXPERIMENTAL APPROACH

Tranilast (400 mg.kg(-1).day(-1)) was orally administered for 8 weeks to mice with established collagen-induced arthritis. Arthritis was assessed by clinical signs and X-ray scores. In paw tissue, the numbers of mast cells and osteoclasts were measured by histological analysis, and several inflammatory factors were assessed by RT-PCR and Western blot analysis.*

KEY RESULTS

TNF-alpha-positive mast cells were present extensively throughout the inflamed synovium of vehicle-treated arthritic mice, with some mast cells in close proximity to osteoclasts in areas of marked bone and cartilage destruction. Tranilast significantly reduced clinical and X-ray scores of arthritis and decreased numbers of TNF-alpha-positive mast cells and mRNA levels of TNF-alpha, chymase (mouse mast cell protease 4), tryptase (mouse mast cell protease 6), stem cell factor, interleukin-6, cathepsin-K, receptor activator of nuclear factor-kappaB, and of receptor activator of nuclear factor-kappaB-ligand, but increased interleukin-10 mRNA level in paws of arthritic mice. Osteoclast numbers were decreased by treatment with tranilast.

CONCLUSIONS AND IMPLICATIONS

Tranilast possesses significant anti-rheumatic efficacy and, probably, this therapeutic effect is partly mediated by inhibition of mast cell activation and osteoclastogenesis.

Avenanthramides, polyphenols from oats, inhibit IL-1beta-induced NF-kappaB activation in endothelial cells

The chronic inflammation of arterial walls is associated with the development of atherosclerosis. Earlier we reported that avenanthramide (Avn)s-enriched extract of oats (AvnsO) significantly suppressed interleukin (IL)-1beta-stimulated secretion of proinflammatory cytokines, such as IL-6, IL-8, and MCP-1, by human aortic endothelial cells (HAEC). The main objective of the current study was to determine if the mechanism of inhibitory effect of these polyphenols from oats on the expression of proinflammatory cytokines is mediated through modulation of nuclear factor kappaB (NF-kappaB)-dependent transcription. Confluent HAEC monolayers were treated for 24 h with AvnsO, and synthetically prepared Avn-c suppressed IL-beta-stimulated activation of NF-kappaB in a concentration-dependent manner. CH3-Avn-c, a synthetically prepared methyl ester derivative of Avn-c with a high biological potency, significantly and dose dependently decreased mRNA expression and secretion of IL-6, IL-8, and MCP-1 by HAEC as determined by real-time RT-PCR and ELISA, and it inhibited IL-1beta- and TNFalpha-stimulated NF-kappaB activation as determined by a NF-kappaB DNA binding assay and a NF-kappaB luciferase reporter assay. AvnsO and Avn-c as well as CH3-Avn-c also inhibited the NF-kappaB-dependent reporter gene expression activated by TNFR-associated factor 2 and 6 (TRAF2, TRAF6) and NFkappaB-inducing kinase (NIK). CH3-Avn-c also significantly and dose dependently decreased the phosphorylation level of IkappaB kinase (IKK) and IkappaB, and prevented IkappaB degradation as measured by Western blotting. In addition, CH3-Avn-c markedly increased the overall levels of high mass ubiquitin-conjugated protein levels while it mildly inhibited proteasome activity. These observations suggest that Avns, unique polyphenols from oats, decrease the expression of endothelial proinflammatory cytokines at least in part through inhibition of NF-kappaB activation by inhibiting the phosphorylation of IKK and IkappaB, and by suppressing proteasome activity.

Avenanthramides are bioavailable and have antioxidant activity in humans after acute consumption of an enriched mixture from oats

The consumption of polyphenols is associated with a decreased risk of cardiovascular disease. Avenanthramides (AV), alkaloids occurring only in oats, may have anti-atherosclerotic activity, but there is no information concerning their bioavailability and bioactivity in humans. We characterized the pharmacokinetics and antioxidant action of avenanthramide A, B, and C in healthy older adults in a randomized, placebo-controlled, 3-way crossover trial with 1-wk washout periods. Six free-living subjects (3 mol/L, 3 F; 60.8 +/- 3.6 y) consumed 360 mL skim milk alone (placebo) or containing 0.5 or 1 g avenanthramide-enriched mixture (AEM) extracted from oats. Plasma samples were collected over a 10-h period. Concentrations of AV-A, AV-B, and AV-C in the AEM were 154, 109, and 111 micromol/g, respectively. Maximum plasma concentrations of AV (free + conjugated) after consumption of 0.5 and 1 g AEM were 112.9 and 374.6 nmol/L for AV-A, 13.2 and 96.0 nmol/L for AV-B, and 41.4 and 89.0 nmol/L for AV-C, respectively. Times to reach the C(max) for both doses were 2.30, 1.75, and 2.15 h for AV-A, AV-B, and AV-C and half times for elimination were 1.75, 3.75, and 3.00 h, respectively. The elimination kinetics of plasma AV appeared to follow first-order kinetics. The bioavailability of AV-A was 4-fold larger than that of AV-B at the 0.5 g AEM dose. After consumption of 1 g AEM, plasma reduced glutathione was elevated by 21% at 15 min (P < or = 0.005) and by 14% at 10 h (P < or = 0.05). Thus, oat AV are bioavailable and increase antioxidant capacity in healthy older adults.

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.

Sophorae radix extract inhibits high glucose-induced vascular cell adhesion molecule-1 up-regulation on endothelial cell line

BACKGROUND

Sophorae radix (SR) has been used for various diseases including atherosclerosis and arrhythmias. Atherosclerosis induced by hyperglycemia is an important factor in the promotion of diabetic complications. An early event in atherosclerosis is the adhesion of monocytes to endothelium via adhesion molecules. Among them, vascular cell adhesion molecule-1 (VCAM-1) expression mediates the binding of monocytes and lymphocytes to vascular endothelial cells.

METHODS

The study was performed on vascular endothelial cells (ECV304 cells) that were pretreated with various concentrations of SR extract for 3 h before exposure with high glucose (55.5 mmol/l) for 48 h. The protein expression of VCAM-1 was measured by enzyme-linked immunosorbent assay (ELISA) and its mRNA expression was by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

SR extract significantly inhibited high glucose-induced expression of VCAM-1 in a dose-dependent manner and reduced the level of VCAM-1 mRNA through interfering with translocation of nuclear factor-kappaB (NF-kappaB). Decreased VCAM-1 expression by SR extract was associated reduction of adherence between high glucose-stimulated ECV304 cells and human monocyte-like HL-60 cells.

CONCLUSIONS

These data suggest that SR extract inhibits high glucose-mediated monocytes-endothelial cells adhesions and expression of VCAM-1 via inhibition of NF-kappaB translocation.

Tranilast: a novel weapon against insulin resistance

Oxidative stress and inflammatory cytokines such as monocyte chemoattractant protein 1 (MCP-1), TGF-beta, and IL-2 are supposed to play crucial roles in the pathogenesis of insulin resistance (IR). Tranilast is an anti-allergic drug which exerts anti-inflammatory and anti-angiogenesis effects through inhibition of expression of MCP-1, TGF-beta, and antigen-induced IL-2 lymphocyte responsiveness. It also possesses a certain antioxidant activity. Considering the above facts and in view of its safety, tranilast may prove invaluable in the treatment of IR.

The antiatherogenic potential of oat phenolic compounds

Avenanthramides are phenolic antioxidants, which are present in oats. Avenanthramides A, B, and C are the major constituents of the total soluble antioxidant phenolic compounds in oats. We tested the potential antiatherogenic activity of partially purified avenanthramides from oats by examining their effects on adhesion of monocytes to human aortic endothelial cell (HAEC) monolayers, expression of adhesion molecules, and production of proinflammatory cytokines and chemokines by HAEC. The oat avenanthramides mixture was prepared and partially purified by column chromatography. This avenanthramide-enriched mixture (AEM) had no toxicity to HAEC as tested up to 40 ng/ml. The pre-incubation of HAEC with 4, 20, and 40ng/ml AEM for 24h significantly decreased adhesion of U937 monocytic cells to interleukin (IL)-1beta-stimulated HAEC in a concentration-dependent manner. Pre-incubation of HAEC with AEM at 20 and 40 microg/ml, but not at 4 microg/ml, for 24h significantly suppressed IL-1beta-stimulated expressions of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin and the secretion of proinflammatory cytokines IL-6, chemokines IL-8 and monocyte chemoattractant protein (MCP)-1. These data provide evidence for the potential anti-inflammatory and antiatherogenic effects of antioxidant avenanthramides present in oats.

Risk of coronary artery disease associated with polymorphism of the cytochrome P450 epoxygenase CYP2J2

BACKGROUND

Cytochrome P450 (CYP) 2J2 is expressed in the vascular endothelium and metabolizes arachidonic acid to biologically active epoxyeicosatrienoic acids (EETs). The EETs are potent endogenous vasodilators and inhibitors of vascular inflammation. However, it is not known whether genetic polymorphisms of CYP2J2 are associated with increased cardiovascular risks.

METHODS AND RESULTS

All 9 exons of the CYP2J2 gene and its proximal promoter were sequenced in 132 patients to identify potential variants. Functional consequence of a single nucleotide polymorphism (SNP) in the promoter of CYP2J2 was further evaluated by use of transcription factor-binding and reporter assays. A total of 17 polymorphisms were identified. One of the most relevant polymorphisms in terms of frequency and functional importance is located at -50 (G-50T) in the proximal promoter of CYP2J2. Screening of 289 patients with coronary artery disease and 255 control subjects revealed 77 individuals with the G-50T SNP (17.3% of coronary artery disease patients, 10.6% of control subjects; P=0.026). The association of the G-50T polymorphism remained significant after adjustment for age, gender, and conventional cardiovascular risk factors (OR, 2.23; 95% CI, 1.04 to 4.79). The G-50T mutation resulted in the loss of binding of the Sp1 transcription factor to the CYP2J2 promoter and resulted in a 48.1+/-2.4% decrease in CYP2J2 promoter activity (P<0.01). Plasma concentrations of stable EET metabolites were significantly lower in individuals with the G-50T SNP.

CONCLUSIONS

A functionally relevant polymorphism of the CYP2J2 gene is independently associated with an increased risk of coronary artery disease.

Selective Inhibition of Protein Kinase Cβ 2 Prevents Acute Effects of High Glucose on Vascular Cell Adhesion Molecule-1 Expression in Human Endothelial Cells

Background— Enhanced expression of adhesion molecules by the endothelium may account for vascular damage in diabetics and nondiabetic patients who develop stress hyperglycemia during acute myocardial infarction. We analyzed the phosphorylation of protein kinase Cβ 2 (PKCβ 2 ) at serine/threonine residues, which may contribute to the endothelial dysfunction during acute hyperglycemia. Furthermore, this study was designed to investigate whether selective blockade of this regulatory mechanism may prevent the development of endothelial hyperadhesiveness.

Methods and Results— Incubation of the human aortic endothelial cells with high glucose (22.2 mmol/L) resulted in significant increase of vascular cell adhesion molecule (VCAM)-1 protein expression (172±15% versus control; P <0.01). Phorbol 12-myristate 13-acetate, a potent activator of PKC, mimicked the effect of high glucose on VCAM-1 expression. High glucose led to a rapid increase (181±22% versus control; P <0.01) of membrane-bound PKCβ, reflecting activation of this enzyme. The nonselective inhibitor of PKCβ 1 and PKCβ 2 isoforms LY379196, as well as CGP53353, a highly selective inhibitor of PKCβ 2 , prevented in a dose-dependent manner upregulation of VCAM-1. Incubation with high glucose was associated with increased PKCβ 2 phosphorylation at the Ser-660 residue, and both LY379196 and CGP53353 prevented this event. Exposure of the cells to high glucose also reduced the protein level of the inhibitory subunit of nuclear factor-κB, IκBα, leading to its enhanced binding activity. Selective inhibition of PKCβ abolished IκBα degradation.

Conclusions— Our findings demonstrate for the first time that phosphorylation of Ser-660 represents a selective regulatory mechanism for glucose-induced upregulation of VCAM-1. Therefore, PKCβ 2 -selective inhibitors may be promising drugs for treatment of endothelial dysfunction during acute hyperglycemia and possibly in diabetes.