Inhibition of proliferative responses of lymphocytes to food antigens by an anti-allergic drug, N(3',4'-dimethoxycinnamoyl) anthranilic acid (Tranilast) in children with atopic dermatitis

Specific NLRP3 inflammasome inhibitors: promising therapeutic agents for inflammatory diseases

Innate immunity serves as a first line of defence against danger signals, invading pathogens and microbes. The inflammasomes, as pattern recognition receptors, sense these danger signals to initiate pro-inflammatory cascades. The nucleotide-binding domain leucine-rich repeat and pyrin domain containing receptor 3 (NLRP3) inflammasome is the most well characterised inflammasome, and its aberrant activation is implicated in many inflammatory diseases. In the past decade, targeting the NLRP3 inflammasome has become an emerging strategy for inflammatory diseases. To avoid off-target immunosuppressive effects, specific NLRP3 inhibitors have been developed and show promising therapeutic effects. This review discusses the therapeutic effects and clinical perspectives of specific NLRP3 inhibitors, as well as recent progress in the development of these inhibitors for the treatment of inflammatory diseases.

Development of Sustained-Release Ophthalmic Formulation Based on Tranilast Solid Nanoparticles

Eye drops containing Tranilast (TL), N-(3,4-dimethoxycinnamoyl) anthramilic acid, are used as an anti-allergic conjunctivitis drug in the ophthalmic field. Traditional eye drops are very patient compliant, although the bioavailability (BA) of most eye drops is low since eye drops cannot be instilled beyond the capacity of the conjunctival sac due to its limited volume. Thus, traditional eye drops have low BA and a short duration of the drug on the ocular surface, so solutions to these problems are highly anticipated. In this study, we designed a sustained-release drug-delivery system (DDS) for TL nanoparticles. TL nanoparticles were prepared by bead mill treatment, and the gel formulations containing TL nanoparticles (TL-NPs-Gel, particle size 50 nm–100 nm) were provided by carboxypolymethylene. The crystal structure of TL with and without bead mill treatment is the same, but the TL solubility in formulations containing nanoparticles was 5.3-fold higher compared with gel formulations containing TL microparticles (TL-MPs-Gel). The photo and thermal stabilities of TL-NPs-Gel are also higher than those of dissolved TL. Moreover, when TL-NPs-Gel is applied to the upper eyelid skin (outside), the TL is released as nanoparticles, and delivered to the lacrimal fluid through the meibomian glands. In addition, the TL release profile for TL-NPs-Gel was sustained over 180 min after the treatment. These findings can be used to develop a sustained-release DDS in the ophthalmic field.

Cocktail of chemical compounds robustly promoting cell reprogramming protects liver against acute injury

Tissue damage induces cells into reprogramming-like cellular state, which contributes to tissue regeneration. However, whether factors promoting the cell reprogramming favor tissue regeneration remains elusive. Here we identified combination of small chemical compounds including drug cocktails robustly promoting in vitro cell reprogramming. We then administrated the drug cocktails to mice with acute liver injuries induced by partial hepatectomy or toxic treatment. Our results demonstrated that the drug cocktails which promoted cell reprogramming in vitro improved liver regeneration and hepatic function in vivo after acute injuries. The underlying mechanism could be that expression of pluripotent genes activated after injury is further upregulated by drug cocktails. Thus our study offers proof-of-concept evidence that cocktail of clinical compounds improving cell reprogramming favors tissue recovery after acute damages, which is an attractive strategy for regenerative purpose.

Tranilast Blocks the Interaction between the Protein S100A11 and Receptor for Advanced Glycation End Products (RAGE) V Domain and Inhibits Cell Proliferation

The human S100 calcium-binding protein A11 (S100A11) is a member of the S100 protein family. Once S100A11 proteins bind to calcium ions at EF-hand motifs, S100A11 changes its conformation, promoting interaction with target proteins. The receptor for advanced glycation end products (RAGE) consists of three extracellular domains, including the V domain, C1 domain, and C2 domain. In this case, the V domain is the target for mutant S100A11 (mS100A11) binding. RAGE binds to the ligands, resulting in cell proliferation, cell growth, and several signal transduction cascades. We used NMR and fluorescence spectroscopy to demonstrate the interactions between mS100A11and RAGE V domain. The tranilast molecule is a drug used for treating allergic disorders. We discovered that the RAGE V domain and tranilast would interact with mS100A11 by using (1)H-(15)N HSQC NMR titrations. According to the results, we obtained two binary complex models from the HADDOCK program, S100A11-RAGE V domain and S100A11-tranilast, respectively. We overlapped two binary complex models with the same orientation of S100A11 homodimer and demonstrated that tranilast would block the binding site between S100A11 and the RAGE V domain. We further utilized a water-soluble tetrazolium-1 assay to confirm this result. We think that the results will be potentially useful in the development of new anti-cancer drugs.

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.

Tranilast administration reduces fibrosis and improves fatigue resistance in muscles of mdx dystrophic mice

BACKGROUND

Duchenne muscular dystrophy (DMD) is a severe and progressive muscle-wasting disorder caused by mutations in the dystrophin gene that result in the absence of the membrane-stabilising protein dystrophin. Dystrophic muscle fibres are susceptible to injury and degeneration, and impaired muscle regeneration is associated with fibrotic deposition that limits the efficacy of potential pharmacological, cell- and gene-based therapies. Novel treatments that can prevent or attenuate fibrosis have important clinical merit for DMD and related neuromuscular diseases. We investigated the therapeutic potential for tranilast, an orally bioavailable anti-allergic agent, to prevent fibrosis in skeletal muscles of mdx dystrophic mice.

RESULTS

Three-week-old C57Bl/10 and mdx mice received tranilast (~300 mg/kg) in their food for 9 weeks, after which fibrosis was assessed through histological analyses, and functional properties of tibialis anterior muscles were assessed in situ and diaphragm muscle strips in vitro. Tranilast administration did not significantly alter the mass of any muscles in control or mdx mice, but it decreased fibrosis in the severely affected diaphragm muscle by 31% compared with untreated mdx mice (P < 0.05). A similar trend of decreased fibrosis was observed in the tibialis anterior muscles of mdx mice (P = 0.10). These reductions in fibrotic deposition were not associated with improvements in maximum force-producing capacity, but we did observe small but significant improvements in the resistance to fatigue in both the diaphragm and TA muscles of mdx mice treated with tranilast.

CONCLUSION

Together these findings demonstrate that administration of potent antifibrotic compounds such as tranilast could help preserve skeletal muscle structure, which could ultimately increase the efficacy of pharmacological, cell and gene replacement/correction therapies for muscular dystrophy and related disorders.

Effects of topical tranilast on corneal haze after photorefractive keratectomy

PURPOSE

To determine whether topical tranilast might reduce corneal haze through suppression of transforming growth factor (TGF)-beta1 synthesis in keratocyte after photorefractive keratectomy.

SETTING

Department of Ophthalmology, Korea University College of Medicine, Seoul, Republic of Korea.

METHODS

Photorefractive keratectomy was performed on 48 eyes of 28 white rabbits and 24 eyes in a tranilast group were treated with tranilast solution, and the other 24 eyes in control group were treated with saline after laser ablation. The grades of corneal haze at 1, 2, 4, and 8 weeks after surgery were evaluated in 10 eyes of each group for comparison. Immunohistochemistry was performed on 10 eyes of each group, and Western blot analysis was done on 4 eyes of each group for studying TGF-beta1 expression at postoperative day 7.

RESULTS

There was no statistically significant difference in corneal haze between 2 groups from week 1 to week 4 after surgery, but a significant difference was found at week 8 after photorefractive keratectomy (P=.02). The mean number of keratocytes that expressed TGF-beta1 in the tranilast group was 58.3 (+/-17.2), which showed significant difference, compared with that of the control group, 104.5 (+/-23.0) (P<.01). Western blot analysis also revealed that the amount of TGF-beta1 in tranilast group was slightly less than the control group.

CONCLUSIONS

Topical tranilast could reduce corneal haze by suppressing TGF-beta1 expression in keratocytes after photorefractive keratectomy.

Effects of tranilast on filtering blebs: a pilot study

PURPOSE

To investigate the effects of topical instillation of 0.5% tranilast eye drops on intraocular pressure (IOP) and bleb formation after glaucoma filtering surgery.

PATIENTS AND METHODS

This was a prospective, randomized, double-masked, and controlled clinical trial. A total of 52 eyes of 52 patients were randomly assigned to receive either 0.5% tranilast eye drops (24 eyes) or vehicle saline solution (28 eyes) 4 times daily for 3 months after trabeculectomy. Features of the bleb, such as vascularization and size, and intraocular pressure were studied.

RESULTS

The incidence of vascularized bleb and "pseudopod" formation 6 months post treatment were more common in tranilast-treated eyes than control eyes (P = 0.019 and P = 0.043, respectively). The bleb was significantly larger at 6 and 12 months (P = 0.024 and P = 0.049, respectively), and reduction of the IOP was more significant for 2 years postoperatively (P = 0.002 to P = 0.032) in tranilast-treated eyes than control eyes. No vision-threatening side reactions were associated with tranilast.

CONCLUSIONS

The use of topical tranilast after filtering surgery alleviates ischemia of the filtering bleb, reduces IOP, and increases the size of the bleb.

The effect of H1 receptor antagonists on peripheral blood mononuclear cells, adenoid cells and primary cell lines

This study describes the in vitro effect of three H1 receptor antagonists (dexchlorpheniramine, terfenadine and loratadine) on human peripheral blood mononuclear cells (PBMC, n = 30) from allergic patients and healthy individuals. The three H1 receptor antagonists significantly inhibited antigen/mitogen-induced PBMC proliferation in a concentration-dependent manner. Allergen-specific T-cell responses in allergic individuals were similarly inhibited. The effect of the three drugs was also tested in cultures of mononuclear cells derived from adenoid tissue. The growth kinetics were investigated using spontaneously proliferating cell lines to examine whether the inhibition was caused by general toxicity. Three cell lines, HCT 8 (an ileocaecal adenocarcinoma) RPMI 8866 (B-cell line) and 166 A2 (T hybridoma) were tested. Loratadine (< 0.03 microM) and dexchlorpheniramine (< 0.62 microM) altered the kinetics of HCT 8 and RPMI 8866, respectively. When testing RPMI 8866 and 166 A2, the growth-inhibitory effect of terfenadine and loratadine could be neutralized by addition of cell culture filtrate from RPMI 8866 or 166 A2. These culture filtrates are rich in soluble low-affinity IgE receptor (sCD23) and IgE-binding factor (IgEBF), respectively. Our findings show that the antihistamines investigated display some non-convential in vitro anti-allergic properties possibly not related to their interaction with the H1 receptor. In addition, our results suggest: a) The H1 receptor antagonists used differ in their pattern of cell inhibition; b) The inhibitory effect is completely reversible at low drug concentrations.