Noriaki Nagai

A nanoparticle formulation reduces the corneal toxicity of indomethacin eye drops and enhances its corneal permeability

Indomethacin (IMC) has been shown to reduce post-operative inflammation and to decrease intraocular irritation after cataract extraction and in cystoid macular edema; however, the clinical use of its most commonly used eye drops is limited due to topical side-effects that include burning sensation, irritation and epithelial keratitis. It is known that decreasing direct cell stimulation and reducing the amount applied via increasing bioavailability are useful for improving these issues. In this study, we designed ophthalmic formulations containing 0.5% IMC nanoparticles using zirconia beads and Bead Smash 12 (IMCnano eye drops; particle size 76 ± 59 nm, mean ± S.D.), and investigated the corneal toxicity of these IMCnano eye drops. IMCnano eye drops are tolerated better by a human cornea epithelial cell line (HCE-T) than commercially available NDSAIDs preparations (IMC, pranoprofen, diclofenac, bromfenac and nepafenac eye drops), and corneal wound healing in rat eyes with debrided corneal epithelium instilled with IMCnano eye drops is significantly better than that of eyes instilled with commercially available IMC eye drops. In addition, the accumulation of IMC in HCE-T cells treated with the IMCnano eye drops for 30 min was 19.9% that of the accumulation from commercially available IMC eye drops. On the other hand, the corneal penetration of IMC from IMCnano eye drops was significantly greater than in the case of the commercially available IMC eye drops in both in vivo and in vitro studies using rabbit corneas. Taken together, we hypothesize that a nanoparticle formulation reduces the corneal toxicity of IMC eye drops, probably because the accumulation of IMC from IMCnano eye drops in the eye is lower than that from commercially available IMC eye drops. In addition, the nanoparticle formulation may allow a decrease in the amount of IMC used due to the increase in bioavailability, resulting in reduced drug toxicity. These findings provide significant information that can be used to design further studies aimed at developing less toxic eye drops.

Involvement of interleukin 18 in indomethacin-induced lesions of the gastric mucosa in adjuvant-induced arthritis rat

It is well known that nonsteroidal anti-inflammatory drugs (NSAIDs) have significant side effects, such as gastroenteropathy, and rheumatoid arthritis patients taking NSAIDs are more susceptible to NSAIDs-induced gastric lesions in comparison with other patients. The pathogenic mechanism of these lesions is not fully understood. We demonstrate whether interleukin 18 (IL-18) expression relate the aggravation of gastric lesion in adjuvant-induced arthritis (AA) rats following the oral administration of indomethacin. Arthritis was induced by injecting 50 microl of a suspension of 10mg/ml heat-killed butyricum (Mycobacterium butyricum) in Bayol F oil into the plantar region of the right hind foot and tail of Dark Agouti rats resulting in an arthritis incidence of 100%. Two weeks after injection, the rats were administered indomethacin (40mg/kg) orally, and were killed under deep ether anesthesia 6h later. The gastric mucosa was then examined. Oral administration of indomethacin caused hemorrhagic lesions in the gastric mucosa of AA rats, and the lesion score for AA rats following indomethacin treatment was significantly higher than for normal rats administered indomethacin. The expression of the IL-18 mRNA and mature IL-18 protein in the gastric mucosa of AA rats administered indomethacin were also higher in comparison with normal rats receiving indomethacin. In addition, interferon-gamma and nitric oxide levels in the gastric mucosa of AA rats were increased by the oral administration of indomethacin. It is possible that IL-18 expression in AA rats is more sensitive to indomethacin, and the IL-18 may play a role in the aggravation of gastric lesions in AA rats treated with indomethacin.

Effects of instillation of eyedrops containing disulfiram and hydroxypropyl-β-cyclodextrin inclusion complex on endotoxin-induced uveitis in rats.

Objective: To investigate the anti-inflammatory effects of the instillation of disulfirum (DSF) eyedrops that enhance solubility using 2-hydroxypropyl-β-cyclodextrin (HPβCD) and hydroxypropylmethylcellulose (HPMC) on endotoxin-induced uveitis (EIU) in rats and mechanisms related to ocular inflammation. Methods: EIU was induced in male Lewis rats by subcutaneous injection of 200 μg lipopolysaccharide (LPS). DSF (0.125%, 0.25% and 0.5%) or commercially available 0.05% dexamethasone (Dexa) was topically applied to both eyes of rats 1 hour before, immediately after, and 1 and 2 hours after injection of LPS. The aqueous humor (AqH) was collected 24 hours after LPS injection, and the number of infiltrating cells, protein concentration, and levels of tumor necrosis factor-α (TNF-α), nitric oxide (NO) and prostaglandin E2 (PGE2) were determined. Immunohistochemical analysis of the iris ciliary body (ICB) cells was performed to determine the expression of activated nuclear factor κB (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Results: The topical administration with DSF suppressed, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of NO, TNF-α and PGE2 in the AqH and improved the histologic status of the ocular tissue. The anti-inflammatory potency of 0.5% DSF treatment was as strong as that of 0.05% Dexa. Topical DSF treatment also suppressed the activated NF-κB 3 hours after LPS injection, and iNOS and COX-2 expression in the ICB 24 hours after LPS injection. Conclusions: The present results demonstrate that the topical instillation of DSF eyedrops suppresses the inflammation in EIU, suggesting a possible novel approach for the treatment of ocular inflammation.

Topical Therapies for Rheumatoid Arthritis by Gel Ointments containing Indomethacin Nanoparticles in Adjuvant-Induced Arthritis Rat

Indomethacin (IMC), a nonsteroidal anti-inflammatory drug, has been used in the treatment of rheumatoid arthritis (RA), although its clinical use has been limited by its systemic side effects that include gastrointestinal lesions. Therefore, the development of IMC formulations that do not cause gastrointestinal lesions is highly anticipated. In this study, we designed new topical formulations containing IMC solid nanoparticles (IMCnano gel ointment), and investigated their pharmacokinetics. In addition, we demonstrate the preventive effects of this topical application of IMC nanoparticles on inflammation in adjuvant-induced arthritis rat (AA rat). The IMCnano gel ointment was prepared using Bead Smash 12 (a bead mill) and additives including 2-hydroxypropyl-β-cyclodextrin, methylcellulose and Carbopol 934; the mean particle size of the IMC nanoparticles was 173 ± 91 nm (means ± S.D.). The application of the IMCnano gel ointment attenuated the increase in paw edema of the hind feet of AA rats in comparison with AA rats treated with gel ointment containing IMC microparticles (IMCmicro gel ointment, particle diameter 17.1 ± 11.6 mm, means ± S.D). In addition, the accumulation of IMC from the IMCnano gel ointment in skin tissue was significantly large than for the IMCmicro gel ointment; however, the plasma IMC concentrations were similar for the IMCmicro and IMCnano gel ointments. Our findings suggest that the dermal application of nanoparticles may enable a medication to be applied without high-systemic drug levels, which could provide efficient and effective therapy that spares patients from unwanted side effects. A formulation of a topical drug delivery system using IMC nanoparticles may provide a delivery option for the clinical treatment of RA.

Excessive hydrogen peroxide enhances the attachment of amyloid β1–42 in the lens epithelium of UPL rats, a hereditary model for cataracts

Several studies have reported that hydrogen peroxide (H2O2) is related to the toxicity of amyloid β (Aβ), and that the accumulation of Aβ in the lenses of humans causes lens opacification. In this study, we investigate the accumulation of Aβ1-42 in the lenses of UPL rats, which then leads to lens opacification. In addition, we demonstrate the effect of disulfiram eye drops (DSF), a potent radical scavenger, on Aβ1-42 accumulation in the lenses of UPL rats. The H2O2 levels in 46- to 60-day-old UPL rat lenses are significantly higher than in normal rats, and the Aβ1-42 levels in 53- and 60-day-old UPL rats are also increased only in lens epithelium containing capsules (capsule-epithelium), not in the lens cortex and nucleus. However, no increases in amyloid precursor protein (APP), β- or γ-secretase mRNA were observed in lenses of the corresponding ages. It has been thought that Aβ1-42 that accumulates in the lenses of UPL rats is actually produced in another tissue containing neuronal cells, such as brain or retina. Aβ1-42 levels in the brain and retina rise with aging, and the levels of APP, β- and γ-secretase mRNA in the retinas of 53-day-old UPL rats with opaque lenses are significantly higher than in 25-day-old UPL rats with transparent lenses. In contrast to the results in retinas, the levels of APP, β- and γ-secretase mRNA in the brains of 25- and 53-day-old UPL rats are similar. On the other hand, in an in vitro study, Aβ1-42 attachment in the lens capsule-epithelium of UPL rats was found to increase in H2O2. In addition, in an in vivo study, the inhibition of H2O2 by DSF was found to attenuate the increase in Aβ1-42 in the lens capsule-epithelium of 60-day-old UPL rats. Taken together, we hypothesize that excessive H2O2 in the lens enhances the attachment of Aβ1-42 in the lens capsule-epithelium of UPL rats, and that the instillation of DSF has the ability to attenuate the attachment of Aβ1-42 by inhibiting H2O2 production in lens. These findings provide significant information that can be used to design further studies aimed at developing anti-cataract drugs.

Involvement of Interleukin 18 in Lens Opacification of Otsuka Long-Evans Tokushima Fatty Rats, a Model of Human Type 2 Diabetes

Purpose: Mature interleukin 18 (IL-18) leads to the production of interferon-γ, nuclear factor kappa B, and inducible nitric oxide synthase, and we previously reported that the enhancement of IL-18 in lens of hereditary cataract model rats was involved in lens opacification. In this study, we investigated whether the expression of IL-18 relates to lens opacification in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Methods: Male Long-Evans Tokushima Otsuka (LETO) and OLETF rats at 60 weeks of age were used in this study. Expression of IL-18 mRNA was measured by quantitative real-time RT-PCR method, and IL-18 and interferon-γ levels were determined using the ELISA method. The transparency of the lenses was monitored using an EAS-1000, and analyzed by image analysis software connected to the EAS-1000. Results: The plasma levels of glucose, triglycerides and cholesterol in the OLETF rats were significantly higher than in LETO rats as normal controls, and the development of diabetes mellitus was observed. The gene expression levels causing IL-18 activation (IL-18, IL-18 receptor, and caspase-1) are increased at 60 weeks of age, and the levels of IL-18 and interferon-γ in 60-week-old OLETF rat lenses were also higher than those in the 60-week-old LETO rat. Furthermore, the interferon-γ levels increased with increasing IL-18 levels in the lenses of OLETF rat, and a close relationship was observed between the levels of IL-18 and opacity. Conclusion: The expression of IL-18 was increased in the lenses of OLETF rat. It is possible that activated IL-18 in the lenses of OLETF rat may be related to the lens epithelial cell apotosis and lens opacification.

Inhibitory Effects of Oral Disulfiram on Endotoxin-Induced Uveitis in Rats

Purpose: Disulfiram (DSF) exhibits a wide variety of biological activities, including an anti-inflammatory action, on which we focused our attention. The aim of the present study was to investigate the effect of oral DSF on endotoxin-induced uveitis (EIU) in rats. Methods: We investigated its effect upon cellular infiltration and protein leakage, as well as on the concentration of tumor necrosis factor-α (TNF-α), nitric oxide (NO), and prostaglandin E2 (PGE2) in the anterior chamber. Some eyes were enucleated for histologic examination and immunohistochemical analysis. EIU was induced in male Lewis rats by a footpad injection of lipopolysaccharide (LPS). One hour before the LPS injection, either 250, 500, or 750 mg/kg DSF was administered orally. Twenty-four hours later, the aqueous humor was collected from both eyes, and the number of infiltrating cells and protein concentration in the aqueous humor were determined. Levels of TNF-α, NO, and PGE2 were determined by enzyme-linked immunosorbent assay. Immunohistochemical analysis in the iris ciliary body (ICB) cells was perfomed to determine the expression of activated nuclear factor kappa B (NF-κB), inducible-nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Results: The oral administration with DSF suppressed, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of TNF-α, NO, and PGE2 in the aqueous humor and improved the histiologic status of the ocular tissue. The expression of activated NF-κB-positive cells in the ICB was significantly inhibited by oral administrated with DSF 3 hr after the LPS injection. The LPS-induced increased expressions of iNOS and COX-2 proteins in the ICB were also inhibited by oral DSF 24 hr after LPS injection. Conclusions: The present results indicate that oral DSF suppresses the inflammation in EIU by inhibiting the NF-κB-dependent pathway and the subsequent production of pro-inflammatory mediators.

Inhibitive effects of enhanced lipid peroxidation on Ca2+-ATPase in lenses of hereditary cataract ICR/f rats

Our previous studies have demonstrated that the instillation of eye drops containing disulfiram, a radical scavenger and nitric oxide synthase inhibitor, delays cataract development in ICR/f rats, and we have suggested that the production of nitric oxide (NO) and lipid peroxide (LPO) in the lens may relate to the delay in cataract development brought about by disulfiram. However, the involvement of NO and LPO in lenses of ICR/f rats during cataract development has not yet been established. In the present study, we determined changes in NO and LPO levels in lenses of ICR/f rats during cataract development. Opacification of ICR/f rat lenses started at 77 days of age, and the lenses of 91-day-old ICR/f rats were almost entirely opaque. The Ca(2+)-ATPase activity in the lenses of ICR/f rats decreased with increasing age, and an elevation in Ca(2+) content was observed in ICR/f rat lenses with the decrease in Ca(2+)-ATPase activity. NO levels in the lenses of ICR/f rats increased from 63 to 85 days of age, reaching a maximum at 77 days of age. In addition, LPO levels in the lenses of ICR/f rats also increased with increasing age. LPO levels in the lenses of 63- to 91-day-old ICR/f rats were found to be significantly higher compared with those in 22-day-old ICR/f rats. These changes of Ca(2+), Ca(2+)-ATPase, NO and LPO were attenuated by instillation of DSF eye drops. These results suggest that excessive NO may cause enhanced lipid peroxidation resulting in the inhibition of Ca(2+)-ATPase. The decrease in Ca(2+)-ATPase activity may cause the elevation in lens Ca(2+), leading to lens opacification in ICR/f rats.

Intravenous Administration of Cilostazol Nanoparticles Ameliorates Acute Ischemic Stroke in a Cerebral Ischemia/Reperfusion-Induced Injury Model

It was reported that cilostazol (CLZ) suppressed disruption of the microvasculature in ischemic areas. In this study, we have designed novel injection formulations containing CLZ nanoparticles using 0.5% methylcellulose, 0.2% docusate sodium salt, and mill methods (CLZnano dispersion; particle size 81 ± 59 nm, mean ± S.D.), and investigated their toxicity and usefulness in a cerebral ischemia/reperfusion-induced injury model (MCAO/reperfusion mice). The pharmacokinetics of injections of CLZnano dispersions is similar to that of CLZ solutions prepared with 2-hydroxypropyl-β-cyclodextrin, and no changes in the rate of hemolysis of rabbit red blood cells, a model of cell injury, were observed with CLZnano dispersions. In addition, the intravenous injection of 0.6 mg/kg CLZnano dispersions does not affect the blood pressure and blood flow, and the 0.6 mg/kg CLZnano dispersions ameliorate neurological deficits and ischemic stroke in MCAO/reperfusion mice. It is possible that the CLZnano dispersions will provide effective therapy for ischemic stroke patients, and that injection preparations of lipophilic drugs containing drug nanoparticles expand their therapeutic usage.

Pharmacokinetics and Antiinflammatory Effect of a Novel Gel System Containing Ketoprofen Solid Nanoparticles

We previously reported that dermal application using nanoparticles improves skin penetration. In this study, we prepared novel topical formulations containing ketoprofen (KET) solid nanoparticles (KETnano gel ointment) and investigated the antiinflammatory effect of the KET nanoparticle formulations on rheumatoid arthritis using adjuvant-induced arthritis (AA) rats. The KETnano gel ointment was prepared using a bead mill method and additives including methylcellulose and Carbopol 934; the mean particle size of the KET nanoparticles was 83 nm. In the in vitro skin penetration experiment, the penetration rate (Jc) and penetration coefficient through the skin (Kp) values of the KETnano gel ointment were significantly higher than those of gel ointment containing KET microparticles (KETmicro gel ointment; mean particle size 7.7 µm). On the other hand, in the in vivo percutaneous absorption experiment, the apparent absorption rate constant (ka) and the areas under the KET concentration-time curve values in the skin of rats receiving the KETnano gel ointment were significantly higher than those of rats receiving the KETmicro gel ointment, and the amounts of KET in the skin tissues of rats receiving the KETnano gel ointment were also significantly higher than those of rats receiving the KETmicro gel ointment. In addition, the application of the KETnano gel ointment attenuated the enhancement of paw edema of the hind feet of AA rats more than the application of the KETmicro gel ointment. Our findings suggest that a topical drug delivery system using nanoparticles could lead to expansion in the therapeutic use of KET.