Cytoprotective effects of rebamipide and carteolol hydrochloride against ultraviolet B-induced corneal damage in mice

Ocular topical application of alpha-glucosyl hesperidin as an active pharmaceutical excipient: in vitro and in vivo experimental evaluation

Alpha-glucosyl hesperidin (GH) is an aqueous soluble, amphipathic hesperidin derivative with several pharmacological effects, and it is postulated in this manuscript that GH could potentially be utilized as an active pharmaceutical excipient in eyedrops. The ocular safety of GH was evaluated according to in vitro cytotoxicity and in vivo ocular tolerance. The in vivo corneal permeation of coumarin-6 (Cou-6) with or without GH was characterized, and the in vivo inducing corneal wound healing using bisdemethoxycurcumin (BDMC) with or without GH was also evaluated to determine whether GH is an active pharmaceutical excipient in eyedrops. The results demonstrated that as high as 30 mg/ml of GH exhibits high-level in vitro and in vivo safety profiles according to four in vitro and in vivo evaluations. GH improved the corneal permeation of Cou-6 in mice, as well as demonstrated in vitro antioxidant activity. Concerning in vivo activity, a BDMC-GH suspension was shown to be synergistic in promoting corneal wound healing in mice, as well as restoring corneal sensitivity, promoting corneal epithelial wound healing, and restoring the corneal tissue structure without inflammatory cell infiltration. Overall, GH could be a novel and promising active excipient in eyedrops.

The Development of Super-Saturated Rebamipide Eye Drops for Enhanced Solubility, Stability, Patient Compliance, and Bioavailability

The present study aimed to develop clear aqueous rebamipide (REB) eye drops to enhance solubility, stability, patient compliance, and bioavailability. For the preparation of a super-saturated 1.5% REB solution, the pH-modification method using NaOH and a hydrophilic polymer was employed. Low-viscosity hydroxypropyl methylcellulose (HPMC 4.5cp) was selected and worked efficiently to suppress REB precipitation at 40 °C for 16 days. The additionally optimized eye drops formulation (F18 and F19) using aminocaproic acid and D-sorbitol as a buffering agent and an osmotic agent, respectively, demonstrated long-term physicochemical stability at 25 °C and 40 °C for 6 months. The hypotonicity (<230 mOsm) for F18 and F19 noticeably extended the stable period, since the pressure causing the REB precipitation was relieved compared to the isotonic. In the rat study, the optimized REB eye drops showed significantly long-lasting pharmacokinetic results, suggesting the possibility of reducing daily administration times and increasing patient compliance (0.50- and 0.83-times lower Cmax and 2.60- and 3.64-times higher exposure in the cornea and aqueous humor). In conclusion, the formulations suggested in the present study are promising candidates and offer enhanced solubility, stability, patient compliance, and bioavailability.

Ultraviolet B irradiation induces senescence of human corneal endothelial cells in vitro by DNA damage response and oxidative stress

The human corneal endothelial cells (HCEnCs) play a vital role in the maintenance of corneal transparency and visual acuity. In our daily life, HCEnCs are inevitably exposed to ultraviolet B (UVB) radiation leading to decreases of visual acuity and corneal transparency resulting in visual loss eventually. Therefore, understanding the UVB-induced cytotoxicity in HCEnCs is of importance for making efficient strategies to protect our vision from UVB-damage. However, in-depth knowledge about UVB-induced cytotoxicity in HCEnCs is missing. Herein, we pulse-irradiated the HCEnCs in vitro with 150 mJ/cm² UVB (the environmental dose) at each subculture for 4 passages to explore the insights into UVB-induced phototoxicity. The results showed that the UVB-treated HCEnCs exhibit typical senescent characteristics, including significantly enlarged relative cell area, increased senescence-associated β-galactosidase positive staining, and upregulated p16^INK4A and senescence associated secretory phenotypes (SASPs) such as CCL-27, IL-1α/6/8/10, TGF-β1 and TNF-α, as well as decreased cell proliferation and Lamin B1 expression, and translocation of Lamin B1. Furthermore, we explored the causative mechanisms of senescence and found that 150 mJ/cm² UVB pulse-irradiation impairs DNA to activate DNA damage response (DDR) pathway of ATM-p53-p21^WAF1/CIP1 with downregulated DNA repair enzyme PARP1, leading to cell cycle arrest resulting in DDR-mediated senescence. Meanwhile, UVB pulse-irradiation also elicits a consistent increase of ROS production to aggravate DNA damage and impose oxidative stress on energy metabolism leading to metabolic disturbance resulting in metabolic disturbance-mediated senescence. Altogether, the repeated pulse-irradiation of 150 mJ/cm² UVB induces HCEnC senescence via both DDR pathway and energy metabolism disturbance.

One-Year Ocular Safety Observation of Workers and Estimations of Microorganism Inactivation Efficacy in the Room Irradiated with 222-Nm far Ultraviolet-C Lamps

Two krypton-chloride germicidal excimer lamp units (Care222 TRT-104C11-UI-U3, USHIO Inc.) were installed in the examination room of an ophthalmology department. The irradiation dose was set not to exceed the former (i.e., before 2022) threshold limit value (TLV) (22 mJ/cm² /8 hours) recommended by the ACGIH. Section 1: The eyes and lids of the 6 ophthalmologists (5 wore glasses for myopic correction) who worked in the room for a mean stay of 6.7 hours/week were prospectively observed for 12 months. Slitlamp examinations revealed neither acute adverse events such as corneal erosion, conjunctival hyperemia, lid skin erythema nor chronic adverse events such as pterygium, cataract, or lid tumor. The visual acuity, refractive error, corneal endothelial cell density remained unchanged during the study. Section 2: The irradiation of samples placed on the table or floor using the same fixtures in the room (5-7.5 mJ/cm² ) was associated with >99% inhibition of φX174 phage and >90% inhibition of S. aureus. In conclusion, no acute or chronic health effects in human participants was observed in a clinical setting of full-room ultraviolet germicidal irradiation by 222-nm lamp units and high efficacy in deactivation of microorganisms was determined in the same setting.

The Effect of Rebamipide on Refractive Accuracy of Cataract Surgery in Patients with Dry Eye

Introduction

Refractive accuracy is crucial for increasing patient satisfaction after cataract surgery. Tear film instability caused by dry eye can lead to inaccurate measurement of corneal power, which is one of the most important factors for postoperative refractive calculation. This study investigated the effect of 2% rebamipide ophthalmic suspension on the predicted refractive accuracy for cataract surgery in patients with dry eye.

Methods

This single-center, prospective, open-label study included 35 dry eyes (with tear breakup time < 5 s) who underwent cataract surgery. The patients were treated with rebamipide for 4 weeks before the preoperative examination. In addition to the usual evaluation of biometric variables essential for cataract surgery, tear breakup time (TBUT), superficial punctate keratopathy in the central part of the cornea (C-SPK), corneal higher-order aberrations (HOAs), and predicted postoperative spherical equivalent (P-SE) were evaluated at baseline and 4 weeks after dry eye treatment. The patients’ subjective spherical equivalent (S-SE) was evaluated 1 month postoperatively. The difference between S-SE and P-SE was used to assess the accuracy of the P-SE. Improvement in TBUT, C-SPK, HOA, and the accuracy of P-SE after dry eye treatment were analyzed.

Results

The accuracy of the biometry readings for the achieved P-SE was within 0.25 D in 42.9% and 54.3%; within 0.5 D in 71.4% and 88.6%; and within 0.75 D in 88.6% and 97.1% of eyes before and after rebamipide treatment, respectively (p < 0.01). TBUT, C-SPK, and HOAs significantly improved after rebamipide treatment (p < 0.01).

Conclusion

Rebamipide significantly improved the corneal surface condition and accuracy of the predicted postoperative refraction in dry eyes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-022-00457-3.

Cytoprotective Effects of Water Soluble Dihydropyrimidinthione Derivative Against UV-B Induced Human Corneal Epithelial Cell Photodamage

Excessive UV-B exposure is well known to be a risk factor for corneal phototoxicity including direct DNA damage and disturbances in the antioxidant balance. Here, we showed a successful synthesis of a water-soluble and biocompatible small molecule DHPM 1 with dihydropyrimidinthione skeleton, which could effectively protect human corneal epithelial (HCE-2) cells from UV-B damage. In separate experiments, DHPM 1 absorbed UV-B rays and exhibited scavenging activity against intracellular ROS induced by UV-B radiation, thereby reducing the levels of DNA fragmentation. Additionally, UV-B exposure increased the expression of cleaved caspase-3, as well as the ratio of Bax/Bcl-2 at protein levels, while pretreatment with DHPM 1 significantly reversed these changes. To the best of our knowledge, this is the first report of a study based on dihydropyrimidinthione derivatives to develop a promising eye drops, which may well find extensive applications in UV-B caused corneal damage.

Effects of Rebamipide on Differences in Power and Axis of Corneal Astigmatism Between Two Intra-patient Keratometric Measurements in Dry Eyes

Introduction

This study investigated the effect of rebamipide on discrepancies in the power and axis of astigmatism between two intra-patient keratometric measurements in patients with dry eyes.

Methods

Fifty-eight dry eyes (with a short tear breakup time [TBUT] of less than 5 s) were analyzed. Patients with dry eye were treated with 2% rebamipide ophthalmic suspension (group R) or Mytear^® artificial tear ophthalmic solution (group M) for 4 weeks. TBUT and corneal higher-order aberrations (HOAs) were evaluated at baseline and 4 weeks after treatment. Astigmatism power and axis were measured twice during both evaluations, at 5-min intervals. Baseline and post-treatment measurements were compared. Changes in TBUT and HOAs, and intra-patient discrepancies in astigmatism power and axis measurements were evaluated.

Results

HOAs showed significant positive correlations with intra-patient differences in astigmatism power and axis (P < 0.001). At the 4-week post-treatment follow-up, TBUT increased, and HOAs and astigmatism power and axis discrepancies decreased in a significant number of patients in group R (P < 0.001). In group M, only differences in astigmatism power decreased in a significant number of cases (P = 0.005). The degree of change in the intra-patient difference in astigmatism power between the two post-treatment keratometric measurements was significantly greater in group R than in group M (P < 0.001). In group R, baseline HOAs exhibited a significant positive correlation with changes in HOAs and intra-patient differences in astigmatism power (both P < 0.001). In group M, baseline HOAs were only significantly correlated with changes in intra-patient differences in astigmatism power (P = 0.030).

Conclusion

In dry eyes with short TBUTs, rebamipide significantly improved the corneal surface condition and significantly reduced intra-patient discrepancies in astigmatism power and axis measurements. Rebamipide may improve the accuracy of intraocular lens (IOL) power calculations in dry eyes, particularly when toric IOLs are implanted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-021-00368-9.

This study investigated the effect of rebamipide on discrepancies in power and axis of astigmatism between two intra-patient keratometric measurements in patients with dry eyes. Short tear break-up time and corneal high-order aberrations were evaluated at baseline and 4 weeks after treatment. Astigmatism power and axis were measured twice at both evaluations. Baseline and post-treatment measurements were compared, and changes in short tear break-up time and high-order aberrations, as well as intra-patient discrepancies in astigmatism power and axis measurements, were evaluated. High-order aberrations at baseline showed significant positive correlations with intra-patient differences in astigmatism power and axis. Rebamipide significantly improved the corneal surface condition and significantly reduced intra-patient discrepancies in astigmatism power and axis measurements. Rebamipide may improve the accuracy of intraocular lens power calculations in dry eyes, particularly when toric intraocular lenses are implanted.

Protective effects of citicoline-containing eye drops against UVB-Induced corneal oxidative damage in a rat model

It has been reported that citicoline increases antioxidant activity in some tissues. However, the effect of citicoline on corneal wound-healing has not yet been demonstrated. The aim was to investigate the protective effects of citicoline on ultraviolet B (UVB) radiation-induced corneal oxidative damage in a rat model. Four groups (eight animals each) were investigated: controls; UVB only; UVB/citicoline; and citicoline only. Corneal oxidative damage was induced by exposure to UVB radiation at 560 μW/cm² for five days in the UVB-exposed groups and 1% citicoline eye drops were applied (3xday) for eight days in the two citicoline groups. Corneal surface damage was evaluated by opacity and fluorescein staining. Corneal injury was assessed biochemically by measuring the concentrations of glutathione (GSH) and malondialdehyde (MDA) and the activity of corneal superoxide dismutase (SOD) and catalase. Matrix metalloproteinase (MMP) -2 and -9 and caspase-3 were evaluated by immunofluorescent staining and microscopic examination and by Western blot analysis. Corneal gene expression analysis was performed for vascular endothelial growth factor (VEGF), interleukin-1 beta (IL-1β) and transforming growth factor-beta (TGF-β). UVB radiation caused significant epithelial damage and evident opacity in the cornea, together with a local decrease in SOD, catalase and GSH activity. Corneal MDA concentrations increased with UVB exposure. The UVB/Citicoline group had significantly less corneal damage, greater SOD, catalase and GSH activity, and decreased MDA concentrations compared to the UVB only group (p < 0.05). Expression of TGF-β, IL-1β and VEGF was significantly lower in the citicoline/UVB group compared to the UVB group (p < 0.05). Interestingly, TGF-β expression was lower in the citicoline only group compared with controls. Immunfluorescent staining and Western blot analysis showed increased MMP-2, -9 and caspase-3 in the UVB only group compared with the UVB/citicoline group. It was shown that citicoline treatment may be effective in suppressing oxidative stress and controlling inflammation in UVB corneal injury.

Re-Evaluation of Rat Corneal Damage by Short-Wavelength UV Revealed Extremely Less Hazardous Property of Far-UV-C†

Corneal damage‐induced various wavelength UV (311, 254, 235, 222 and 207 nm) was evaluated in rats. For 207 and 222‐UV‐C, the threshold radiant exposure was between 10 000 and 15 000 mJ cm⁻² at 207 nm and between 3500 and 5000 mJ cm⁻² at 222 nm. Penetrate depth to the cornea indicated by cyclobutene pyrimidine dimer (CPD) localization immediately after irradiation was dependent on the wavelength. 311 and 254 nm UV penetrate to corneal endothelium, 235 nm UVC to the intermediate part of corneal stroma, 222 and 207 nm UVC only to the most outer layer of corneal epithelium. CPD observed in corneal epithelium irradiated by 222 nm UVC disappeared until 12 h after. The minimum dose to induce corneal damage of short‐wavelength UV‐C was considerably higher than the threshold limit value (TLV^®) promulgated by American Conference of Governmental Industrial Hygienists (ACGIH). The property that explains why UV‐C radiation at 207 and 222 nm is extremely less hazardous than longer UV wavelengths is the fact that this radiation only penetrates to the outermost layer of the corneal epithelium. These cells typically peel off within 24 h during the physiological turnover cycle. Hence, short‐wavelength UV‐C might be less hazardous to the cornea than previously considered until today.

NAD+ precursors protect corneal endothelial cells from UVB-induced apoptosis

Excessive exposure of the eye to ultraviolet B light (UVB) leads to corneal edema and opacification because of the apoptosis of the corneal endothelium. Our previous study found that nicotinamide (NIC), the precursor of nicotinamide adenine dinucleotide (NAD), could inhibit the endothelial-mesenchymal transition and accelerate healing the wound to the corneal endothelium in the rabbit. Here we hypothesize that NIC may possess the capacity to protect the cornea from UVB-induced endothelial apoptosis. Therefore, a mouse model and a cultured cell model were used to examine the effect of NAD⁺ precursors, including NIC, nicotinamide mononucleotide (NMN), and NAD, on the UVB-induced apoptosis of corneal endothelial cells (CECs). The results showed that UVB irradiation caused apparent corneal edema and cell apoptosis in mice, accompanied by reduced levels of NAD⁺ and its key biosynthesis enzyme, nicotinamide phosphoribosyltransferase (NAMPT), in the corneal endothelium. However, the subconjunctival injection of NIC, NMN, or NAD⁺ effectively prevented UVB-induced tissue damage and endothelial cell apoptosis in the mouse cornea. Moreover, pretreatment using NIC, NMN, and NAD⁺ increased the survival rate and inhibited the apoptosis of cultured human CECs irradiated by UVB. Mechanistically, pretreatment using nicotinamide (NIC) recovered the AKT activation level and decreased the BAX/BCL-2 ratio. In addition, the capacity of NIC to protect CECs was fully reversed in the presence of the AKT inhibitor LY294002. Therefore, we conclude that NAD⁺ precursors can effectively prevent the apoptosis of the corneal endothelium through reactivating AKT signaling; this represents a potential therapeutic approach for preventing UVB-induced corneal damage.

The Effect of Rebamipide Ophthalmic Solution on Cytokine and Mucin Secretion in Culture of Conjunctival Epithelial Cells From the Cu, Zn-Superoxide Dismutase-1 (SOD-1) Knock-Down Mouse

OBJECTIVES

To evaluate the in vitro effects of 1-mM rebamipide ophthalmic solution on the expression of inflammatory cytokines and MUC5AC in Cu, Zn-superoxide dismutase-1 (SOD-1) knock-down conjunctival epithelium.

METHODS

Conjunctival epithelium from C57BL/6 wild-type mice was cultured and treated with rebamipide ophthalmic solution. Using cytometric bead array, we examined the levels of interleukin-(IL)-6, IL-10, IL-17, monocyte chemoattractant protein-1, interferon-γ (INF-γ), tumor necrosis factor, and IL-12p70 in the culture supernatants. The culture supernatants were obtained from the culture medium of nontreated or SOD-1 knock-down conjunctival epithelium using small interfering RNA (siRNA). In addition, ELISA was performed to ascertain the MUC5AC concentration in the culture medium.

RESULTS

After rebamipide ophthalmic solution was applied, IL-6 concentration in the supernatants of conjunctival epithelial cells treated with and without siRNA showed a significant timewise decrease from 0 to 24 hr (963±42 to 0.07±0.05 pg/mL and 932±168 to 2.2±0.05 pg/mL, respectively) (P<0.001). Compared with baseline values, MUC5AC concentrations significantly increased 24 hr after rebamipide application to the conjunctival cultures-both with and without SOD-1 siRNA treatment (P<0.05 in both cases).

CONCLUSIONS

Rebamipide seems to increase MUC5AC levels and suppress inflammation by decreasing IL-6 levels in mouse conjunctival epithelial cell cultures. SOD-1 siRNA-treated mouse conjunctival epithelial cell culture is a practical method for investigating changes in mucosa-associated mucins and proinflammatory cytokines in response to therapeutic interventions.

Medical Treatment for Dry Eye in Japan

The etiology of dry eye has not been clarified. In the United States, the inflammation theory is supported as the main cause of dry eye, whereas the Asia Dry Eye Society has identified tear instability as the main cause. Based on this tear instability concept, the P2Y2 antagonist Diquas and the mucin secretagogue Mucosta were developed and launched in Japan over the last 5 years, and they have been widely prescribed to patients with dry eye. Moreover, Diquas has also been launched in other Asian countries, such as Korea, Thailand, and Vietnam. This report summarizes the efficacy and characteristics of these two eye drops to improve our understanding of dry eye.

Carteolol hydrochloride reduces visible light-induced retinal damage in vivo and BSO/glutamate-induced oxidative stress in vitro

The purpose of this study was to determine whether carteolol eye drops, a β-adrenoceptor antagonist used as an intraocular hypotensive agent, has protective effects against the light-induced oxidative stress in retina. Dark-adapted pigmented rats were pre-treated with topical carteolol ophthalmic solution or saline and then exposed to visible light. The effects on electroretinogram (ERG), morphology, oxidative stress, and expression of mRNAs in the retinas were determined. The l-buthionine-(S,R)-sulfoximine (BSO)/glutamate-induced oxidative stress in 661 W cells, a murine photoreceptor cell line, was evaluated by cell death assays, production of reactive oxygen species (ROS), and activation of caspase. In vivo studies showed that exposure to light caused a decrease in the amplitudes of ERGs and the outer nuclear layer (ONL) thickness and an increase of the 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive cells in the ONL. These changes were significantly reduced by pre-treatment with carteolol. Carteolol also significantly up-regulated the mRNA levels of thioredoxin 1 and glutathione peroxidase 1 compared to saline-treated group. Moreover, carteolol and timolol, another β-adrenoceptor antagonist, significantly inhibited BSO/glutamate-induced cell death and reduced caspase-3/7 activity and ROS production in vitro. Therefore, carteolol could protect retina from light-induced damage with multiple effects such as enhancing the antioxidative potential and decreasing the intracellular ROS production.

Rebamipide suppresses TNF-α production and macrophage infiltration in the conjunctiva

PURPOSE

To evaluate the anti-inflammatory effect of rebamipide during corneal epithelial wound healing using a mouse wound repair model.

METHODS

A 2-mm circular disc of the central cornea was demarcated in the right eye of C57BL/6 mice and the epithelium removed. Rebamipide 2% eyedrop was instilled onto the wounded eye 5 times a day (n = 26). Phosphate-buffered saline (PBS) was used in the control group (n = 26). Corneal and conjunctival IL-1β and TNF-α levels were measured at 6 h and 24 h postinjury by ELISA. The wounded area was evaluated by fluorescein staining at 24 h postinjury. Macrophage infiltration was assessed immunohistochemically, and TNF-α secretion from macrophages was examined in vitro.

RESULTS

Conjunctival IL-1β and corneal IL-1β levels were not significantly different between PBS-treated and rebamipide-treated groups. However, conjunctival TNF-α level was significantly lower in the rebamipide-treated group compared with the PBS-treated group. Macrophage migration into the conjunctiva, but not into the cornea, was suppressed by rebamipide treatment. In addition, TNF-α secretion from cultured macrophages was suppressed by rebamipide in a concentration-dependent manner. Rebamipide treatment significantly accelerated corneal epithelial wound healing at 24 h postinjury.

CONCLUSIONS

In a mouse corneal epithelial wound model, rebamipide suppressed TNF-α secretion and macrophage infiltration in the conjunctiva, which might have contributed to accelerated corneal epithelial wound healing in the first 24 h following injury.

Inhibition of Ultraviolet B-Induced Expression of the Proinflammatory Cytokines TNF-α and VEGF in the Cornea by Fucoxanthin Treatment in a Rat Model

Ultraviolet B (UVB) irradiation is the most common cause of radiation damage to the eyeball and is a risk factor for human corneal damage. We determined the protective effect of fucoxanthin, which is a carotenoid found in common edible seaweed, on ocular tissues against oxidative UVB-induced corneal injury. The experimental rats were intravenously injected with fucoxanthin at doses of 0.5, 5 mg/kg body weight/day or with a vehicle before UVB irradiation. Lissamine green for corneal surface staining showed that UVB irradiation caused serious damage on the corneal surface, including severe epithelial exfoliation and deteriorated epithelial smoothness. Histopathological lesion examination revealed that levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF), significantly increased. However, pretreatment with fucoxanthin inhibited UVB radiation-induced corneal disorders including evident preservation of corneal surface smoothness, downregulation of proinflammatory cytokine expression, and decrease of infiltrated polymorphonuclear leukocytes from UVB-induced damage. Moreover, significant preservation of the epithelial integrity and inhibition of stromal swelling were also observed after UVB irradiation in fucoxanthin-treated groups. Pretreatment with fucoxanthin may protect against UVB radiation-induced corneal disorders by inhibiting expression of proinflammatory factors, TNF-α, and VEGF and by blocking polymorphonuclear leukocyte infiltration.

Topical rebamipide improves lid wiper epitheliopathy

Administration of topical rebamipide increases the mucin level of tear film and improves the ocular surface in short break-up time type of dry eye. Lid wiper epitheliopathy (LWE) is a disorder of the marginal conjunctiva of the upper eyelid with dry eye symptoms. LWE may be related to mechanical forces during blinking resulting in inflammation of the ocular surface. Rebamipide also has various anti-inflammatory effects. In this report, we tried treatment with topical rebamipide for two cases of LWE. One case had been treated with sodium hyaluronate ophthalmic solution and diquafosol sodium eye drops by other doctors for several weeks. The other case was not previously treated. In both cases, fluorescein staining of the cornea and lid margin was remarkably improved, ocular symptoms decreased, and tear film break-up times increased with rebamipide eye drops four times daily for 2-3 weeks. Topical rebamipide was effective for corneal and conjunctival disorders in LWE. This drug may provide a novel approach to the treatment of LWE.

Topical rebamipide improves the ocular surface in mild lagophthalmos

Administration of topical rebamipide improves the ocular surface in dry eye. We consecutively studied seven eyes in seven cases (three males and four females) with mild lagophthalmos (three cases after eyelid surgery, two cases of incomplete facial nerve palsy, and two cases of senile ectropion) during the treatment of corneal disorders with rebamipide eye drops four times daily for 2 weeks. The fluorescein corneal staining (FCS) score, tear film break-up time (TBUT), Schirmer’s test, and decimal visual acuity were examined. Ocular symptoms were examined and scored by questioning each patient before and after administration of the drug. In all seven eyes, inferior corneal erosion decreased or disappeared within 2 weeks after administration of topical rebamipide. The FCS score was significantly improved (P < 0.05). The TBUT was significantly extended from 2.9 ± 0.5 seconds to 5.2 ± 0.4 seconds (P < 0.05). The scores of ocular symptoms, such as eye pain, dryness, blurred vision, and foreign body sensations, were significantly improved (P < 0.05).Topical rebamipide was effective for corneal disorders in mild lagophthalmos. This drug may provide a novel approach to treat lagophthalmos.

Effects of a long-acting ophthalmic formulation of carteolol containing alginic acid on the corneal epithelial barrier function and water retentive effect

PURPOSE

Effects of a long-acting ophthalmic formulation of carteolol containing alginic acid on the corneal epithelial barrier function and its water retentive effect were investigated.

METHODS

Using 10 healthy adult subjects, 2% Mikelan Ophthalmic Solution(®) (MK) was instilled in the eye once daily for 7 days (MK group) and then after a washout period of at least 28 days, 2% Mikelan LA Ophthalmic Solution(®) (MKLA) was instilled in the eye once daily for 7 days (LA group). As an index of the corneal epithelial barrier function, the fluorescein uptake was measured using Kowa FL-500. A Schirmer test was conducted to evaluate the tear dynamics. In another 10 subjects, 0.5% Timoptol(®) (TM) was instilled in the eye unilaterally twice daily for 7 days (TM group), and the tests were conducted in the same manner.

RESULTS

Concerning the fluorescein uptake before and after initiation of instillation, the levels before and at 7 days after initiation of instillation were 20.7 and 26.5 ng/mL, respectively, in the LA group and 20.6 and 26.4 ng/mL, respectively, in the MK group, showing no significant difference between levels before and after initiation of instillation in either group. In the TM group, the levels were 21.4 and 65.5 ng/mL, respectively, showing a significant increase after initiation of instillation. In the Schirmer test, the values before and after initiation of instillation were 16.8 and 20.7 mm, respectively, in the LA group and 13.7 and 12.7 mm, respectively, in the MK group, showing a trend toward increase in the LA group.

CONCLUSIONS

The findings suggest that the long-acting ophthalmic formulation of carteolol containing alginic acid does not affect the corneal epithelial barrier function and that it may possess a water retentive action.

Rebamipide promotes healing of colonic ulceration through enhanced epithelial restitution

AIM: To investigate the efficacy of rebamipide in a rat model of colitis and restitution of intestinal epithelial cells in vitro.

METHODS: Acute colitis was induced with trinitrobenzene sulfonic acid (TNBS) in male Wistar rats. Rats received intrarectal rebamipide treatment daily starting on day 7 and were sacrificed on day 14 after TNBS administration. The distal colon was removed to evaluate the various parameters of inflammation. Moreover, wound healing assays were used to determine the enhanced restitution of rat intestinal epithelial (RIE) cells treated with rebamipide.

RESULTS: Intracolonic administration of rebamipide accelerated TNBS-induced ulcer healing. Increases in the wet weight of the colon after TNBS administration were significantly inhibited by rebamipide. The wound assay revealed that rebamipide enhanced the migration of RIE cells through phosphorylation of extracellular signal-regulated kinase (ERK) and activation of Rho kinase.

CONCLUSION: Rebamipide enema healed intestinal injury by enhancing restitution of RIE cells, via ERK activation. Rebamipide might be a novel therapeutic approach for inflammatory bowel disease.

Carteolol hydrochloride suppresses the generation of reactive oxygen species and rescues cell death after ultraviolet irradiation of cultured lens epithelial cells

Introduction:

Anti-oxidant activities of adrenergic β-blockers are proposed in various organs. The aim of the present study was to investigate the effect of carteolol hydrochloride, an adrenergic β-blocker, on the production of reactive oxygen species (ROS) and the viable cell number after ultraviolet irradiation of cultured lens epithelial cells (LECs).

Materials and Methodology:

Cultured LECs were exposed to 0, 10^–5, 10^–4, and 10^–3 M carteolol hydrochloride for 30 min followed by ultraviolet B (UVB) irradiation at intensity of 100, 200, or 400 mJ/cm². The amount of ROS in the LECs was measured using dichlorodihydrofluorescein at 30 min after exposure to UVB. In addition, the number of living LECs was counted at 15 h after exposure to UVB.

Results:

Exposure to 10^–3 M carteolol hydrochloride significantly decreased the amount of ROS after exposure to UVB at intensities of 100, 200, and 400 mJ/cm². In addition, 10^–3 M carteolol hydrochloride significantly increased the viable cell number after exposure to UVB at 400 mJ/cm². However, 10^–4 and 10^–5M carteolol hydrochloride had no significant effect on ROS or the viable cell number in LECs.

Discussions:

Carteolol hydrochloride protects LECs against UVB irradiation by inhibiting the intracellular production of ROS.

Hydrogen peroxide causes mitochondrial DNA damage in corneal epithelial cells

PURPOSE

To study the effects of hydrogen peroxide exposure on mitochondrial DNA (mtDNA) in cultured human corneal epithelial cells. In addition, we compared the integrity of mtDNA found in epithelial cells isolated from keratoconus (KC) and normal (NL) corneas.

METHODS

Telomerase immortalized human corneal epithelial cell line (hTCEpi) were cultured at pH 7.0 or pH 5.0 with or without 200 microM hydrogen peroxide (H2O2). Immunohistochemistry with a marker for oxidative damage, 8-hydroxy-2'-deoxyguanosine (8-OH-dG), was performed on KC and NL corneas (n = 10). Epithelial cells were isolated from KC corneas (n = 5) and NL corneas (n = 7). Total DNA was extracted, and the mtDNA was analyzed by long extension polymerase chain reaction (LX-PCR). The ratios of mtDNA to nuclear DNA were measured by PCR. The mtDNA control regions were PCR amplified and sequenced.

RESULTS

In the epithelial cell cultures, the full-length LX-PCR mtDNA decreased 54% and 44% in the H2O2 + pH7 cultures and H2O2 + pH5 cultures, respectively. 8-OH-dG was present in all layers of KC epithelial cells but only in superficial layers of NL epithelial cells. The isolated KC and NL epithelial cells had comparable levels of full-length LX-PCR mtDNA (16.2 kb) and smaller sized mtDNA bands (4.3 +/- 0.99 vs 4.0 +/- 0.83 bands per individual, respectively). There were no significant differences in the control region nucleotide sequences in KC and NL epithelia.

CONCLUSIONS

Hydrogen peroxide can significantly degrade LX-PCR mtDNA in vitro. Although the KC epithelium showed a higher degree of oxidative damage, the levels of mtDNA damage in NL and KC epithelial cells were similar to each other.

Effect of OPC-12759 on EGF receptor activation, p44/p42 MAPK activity, and secretion in conjunctival goblet cells

The purpose of the study was to determine if OPC-12759 stimulates secretion from conjunctival goblet cells in culture and if it activates the EGF receptor (EGFR) and p44/p42 mitogen-activated protein kinase (MAPK) to cause mucin secretion. Conjunctival goblet cells were cultured from pieces of male rat conjunctiva. OPC-12759 was added at increasing concentrations and for varying times to the cultured cells. The cholinergic agonist carbachol was used as a positive control. In selected experiments an inhibitor of the EGFR, AG1478, or an inhibitor of the kinase that activates MAPK, U0126, were added before OPC-12759. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay using the lectin UEA-1. Activation of the EGFR and MAPK were determined with Western blotting analysis using antibodies specific to the phosphorylated and the total amounts of these proteins. We found that OPC-12759 induced goblet cell secretion in a time- and concentration-dependent manner. Inhibition of the EGFR with AG1478 blocked secretion stimulated by OPC-12759. Inhibition of MAPK with U0126 also blocked secretion stimulated by OPC-12759. OPC-12759 increased the phosphorylation of the EGFR and MAPK in a time-dependent manner. We concluded that OPC-12759 stimulates secretion from cultured conjunctival goblet cells by activating the EGFR, which then induces MAPK activity.

Management and Therapy of Dry Eye Disease: Report of the Management and Therapy Subcommittee of the International Dry Eye WorkShop (2007)

The members of the Management and Therapy Subcommittee assessed current dry eye therapies. Each member wrote a succinct evidence-based review on an assigned aspect of the topic, and the final report was written after review by and with consensus of all subcommittee members and the entire Dry Eye WorkShop membership. In addition to its own review of the literature, the Subcommittee reviewed the Dry Eye Preferred Practice Patterns of the American Academy of Ophthalmology and the International Task Force (ITF) Delphi Panel on Dry Eye. The Subcommittee favored the approach taken by the ITF, whose recommended treatments were based on level of disease severity. the recommendations of the Subcommittee are based on a modification of the ITF severity grading scheme, and suggested treatments were chosen from a menu of therapies for which evidence of therapeutic effect had been presented.

Corneal NF-kappaB activity is necessary for the retention of transparency in the cornea of UV-B-exposed transgenic reporter mice

To determine the dynamics of Nuclear Factor-kappaB (NF-kappaB) in murine corneal pathology and the role of NF-kappaB in maintaining corneal clarity after ultraviolet B radiation insult, transgenic mice containing NF-kappaB-luciferase reporter were exposed to LPS (bacterial lipopolysaccharide), TNF-alpha (Tumor Necrosis Factor-alpha) or 4 kJ m(-2) UV-B radiation. NF-kappaB decoy oligonucleotides were also administered in some of the UV-B experiments. Following various exposure times, the mice were sacrificed and whole eyes or corneal tissues were obtained. Whole eyes were examined for scattering using a point-source optical imaging technique. Tissue homogenates were examined for luciferase activity using a luminometer. TNF-alpha and LPS-injected NF-kappaB-luciferase transgenic mice demonstrated 3-10-fold increases in cornea NF-kappaB with peak activities at 4 and 6 hr post-injection, respectively. Mice exposed to 4 kJ m(-2) UV-B exhibited a 3-fold increase in NF-kappaB activity 4 hr post-exposure. The administration of NF-kappaB-decoy oligonucleotides to mice had the effect of reducing UV-B-induced NF-kappaB activity in the cornea and significantly increasing the amount of light scattering in UV-B exposed corneas 7 days post-UV-B exposure when compared to sham injected mice. These results indicate that NF-kappaB is activated in cornea in pathologies that involves increased plasma levels of LPS and TNF-alpha, as well as direct UV-B exposure, and suggest that NF-kappaB activation play an essential part in the corneal healing process.

Carteolol hydrochloride protects human corneal epithelial cells from UVB-induced damage in vitro

PURPOSE

To investigate whether carteolol hydrochloride has protective effects against ultraviolet B (UVB)-induced damage in human corneal epithelial cells (HCECs).

METHODS

Cultured HCECs were exposed to a single dose of UVB 300 mJ/cm, and the cell viability was measured 12 hours after the UVB irradiation using a cell-counting kit. Test samples at 0.01-1.0 mmol/L (carteolol hydrochloride, timolol maleate, betaxolol hydrochloride, levobunolol hydrochloride, or nipradilol) were added to the HCECs before, during, or after UVB irradiation. UV absorption spectra for each drug sample were determined using a spectrophotometer. Hydrogen peroxide (H2O2) and carteolol hydrochloride were simultaneously added to the HCECs for 10 minutes, and the cell viability was measured 12 hours later. The ability of carteolol hydrochloride to scavenge superoxide anion (O2) and singlet oxygen (O2) was investigated using the MCLA chemiluminescence method.

RESULTS

UVB irradiation decreased the number of viable HCECs in a dose-dependent manner. Carteolol hydrochloride at 1 mmol/L attenuated the UVB-induced cell damage when added before, during, or after UVB irradiation (P<0.01). Levobunolol hydrochloride at 1 mmol/L (P<0.01) added during or after irradiation and timolol maleate at 0.1 mmol/L or higher (P<0.05) added during irradiation attenuated the UVB-induced cell damage. Betaxolol hydrochloride and nipradilol had no effect. The UV absorption spectra of timolol maleate and levobunolol hydrochloride overlapped with the UVB wavelength spectrum, while carteolol hydrochloride, betaxolol hydrochloride, and nipradilol showed a partial overlap. Carteolol hydrochloride at 1 mmol/L (P<0.05) significantly inhibited H2O2-induced cell damage and was able to scavenge O2 (EC50 value: 48 mmol/L).

CONCLUSIONS

These data strongly suggest that carteolol hydrochloride has a protective action against UVB-induced HCEC damage, and its radical scavenging ability may be an important basis for this effect.