Effects of 20% Human Serum on Corneal Epithelial Toxicity Induced by Benzalkonium Chloride: In Vitro and Clinical Studies

Development of an ophthalmic formulation with a postbiotic of Lactiplantibacillus plantarum CRL 759

The term postbiotics has acquired great interest in recent years. Numerous studies have shown a potential beneficial effect of its use in many inflammatory pathologies. However, it has not been much explored in ocular inflammatory diseases. The aims of this study were to develop and characterise an ophthalmic formulation with a postbiotic of Lactiplantibacillus plantarum CRL 759, and to evaluate its anti-inflammatory actions on murine macrophage stimulated with lipopolysaccharides (LPS) in vitro. First, we evaluated the ability of L. plantarum CRL 759 to generate a supernatant with anti-inflammatory property using different buffers. Then, we studied the stability at different temperatures and storage times of the generated postbiotic. In vitro assays showed that incubation of L. plantarum CRL 759 in modified phosphate buffer according to Sorensen (called POF-759), generated a supernatant that significantly reduced the production of interleukin-6, tumour necrosis factor-α, and nitric oxide by RAW 264.7 cells stimulated with LPS. Furthermore, POF-759 maintained its anti-inflammatory activity at room temperature, 4 and -20 °C, up to 30 days of storage. From the studies reported here, a postbiotic product with anti-inflammatory properties and optimal characteristics for the formulation of eye drops was obtained.

Efficacy of Autologous Serum Gel in Neurotrophic Persistent Corneal Epithelial Defects Combined with Lagophthalmos

INTRODUCTION

To investigate the efficacy of autologous serum gel in patients with lagophthalmos combined with neurotrophic persistent corneal epithelial defects (PEDs).

METHODS

This is retrospective, case-series study enrolled 15 patients with lagophthalmos complicated by neurotrophic PEDs refractory to medical treatment including autologous serum eye drops. They were treated with autologous serum gel in conjunction with conservative treatment. The following information was collected from medical records: demographics, underlying diseases, and past ocular history. PEDs healing time was evaluated with visual acuity, visual analog scale (VAS) scores, esthesiometer scores, and the areas of the epithelial defects.

RESULTS

Six men and nine women with a mean age of 63.3 ± 9.9 years were included. The most common cause of the neurotrophic PEDs and lagophthalmos in this group was postherpetic infection (46.7%) and cerebral hemorrhage (26.7%) each. Two months following treatment with autologous serum gel, there was a reduction in the area of the epithelial defects (from 19.2 ± 9.9 to 0.6 ± 1.5 mm²) and a significant improvement in best-corrected visual acuity (BCVA) (from 0.8 ± 0.5 to 0.5 ± 0.4 logMAR) and VAS scores (from 5.1 ± 1.1 to 2.1 ± 0.6) in 13 eyes (87%). Among the 11 completely healed eyes, the mean epithelial healing time was 3.2 ± 1.8 weeks.

CONCLUSIONS

Autologous serum gel reduces symptoms and promotes corneal epithelialization of refractory neurotrophic PEDs in patients with lagophthalmos. Therefore, it may be well tolerated and a beneficial addition in the management of neurotrophic PEDs in patients with lagophthalmos.

Topical preservative-free ophthalmic treatments: an unmet clinical need

Introduction: The main role of preservatives in eyedrops is to ensure sterility and microbiological integrity of the drug, and to facilitate the penetration of active compounds into the eye. However, several studies documented significant toxic effects induced by preservatives, especially on the ocular surface. Consequently, most of the ophthalmic medications became progressively available in preservative-free (PF) formulations.Areas covered: We analyzed pre-clinical and clinical studies on PF eyedrops with particular attention to common chronic diseases such as dry eye and glaucoma. We discussed about the pros and cons of using PF eyedrops, in terms of efficacy, safety, and social-economic aspects.Expert opinion: There are still unresolved issues that make hard for PF medications to definitively conquer the drug market. Despite robust pre-clinical evidences of less toxicity, the low number of randomized clinical trials does not permit to state that PF eyedrops have, in clinical practice, a similar efficacy or a higher safety compared to preserved forms. These aspects limit their use to chronic diseases requiring long-term therapies with multiple daily instillations, especially in the presence of concomitant ophthalmic diseases that expose to a risk of ocular surface worsening.

Effect of Autologous Serum Eyedrops on Ocular Surface Disease Caused by Preserved Glaucoma Eyedrops

Autologous serum eyedrops (ASE) are effective in treating various ocular surface diseases, including damages induced by long-term use of preserved glaucoma eyedrops. However, there has been no study on whether ASE is effective without stopping the causative eyedrops. This retrospective observational study included 55 patients with ocular-surface diseases caused by long-term use of preserved glaucoma eyedrops: 18 patients who used ASEs for 2 months without discontinuing the use of glaucoma eyedrops (Group 1), 22 patients who used ASEs for 2 months, discontinuing the use of glaucoma eyedrops for the first month (Group 2) and 15 patients who used non-preservative artificial tears for 2 months, discontinuing the use of glaucoma eyedrops for the first month (Group 3). There were no intergroup differences in the baseline values of the Schirmer I test results, tear breakup time (TBUT), ocular surface staining (OSS) score, loss of the meibomian gland, meibum quality and ocular-surface disease index (OSDI). Group 1 showed significant differences in TBUT, OSS score and OSDI at 2 months when compared to the baseline values before treatment, while Group 2 showed significant differences in those values at both 1 and 2 months. There were no differences in any of the parameters at baseline, 1 month or 2 months in Group 3. Our result suggested that ASE is effective for treating ocular surface diseases caused by glaucoma eyedrops containing preservatives and its effects can be expected without interruption of glaucoma eyedrop treatment.

Ocular surface complications of local anticancer drugs for treatment of ocular tumors

Local chemotherapy is increasingly used, either in combination with surgery or as monotherapy, for management of ocular tumors. Yet many of the local chemotherapeutic agents used for ocular tumors are cytotoxic drugs that are frequently associated with toxicities in normal ocular tissues. Understanding and managing these side effects are important because they affect treatment tolerability, outcome and quality of vision. Herein, we review local anticancer drugs administered for the treatment of ocular tumors, with an emphasis on their toxicities to the ocular surface, adnexa and lacrimal drainage system. We provide the underlying mechanisms and management strategies for the ocular side effects. Recent innovations in anticancer immunotherapy and ocular drug delivery systems also are discussed as new potential therapeutic modalities for alleviation of side effects.

Corneal Epithelial Toxicity after Intravitreal Methotrexate Injection for Vitreoretinal Lymphoma: Clinical and In Vitro Studies

Methotrexate is widely used as an intraocular chemotherapy for vitreoretinal lymphoma (VRL). Although corneal toxicity has been reported in patients after intravitreal methotrexate injections, the incidence, outcome, and mechanism of the toxicity are unclear. Herein, we performed a clinical study to evaluate the incidence, predisposing factors, and treatment outcome of corneal epitheliopathy associated with intravitreal methotrexate injection. In addition, we directly investigated cytotoxic effects and mechanisms of methotrexate in cultures of human corneal epithelial cells (CECs). Medical chart reviews revealed that corneal epitheliopathy occurred in 15 eyes (22.7%, 12 patients) out of 66 eyes (45 patients) after intravitreal methotrexate injections for treatment of VRL. The use of topical anti-glaucoma medication was significantly associated with development of corneal epitheliopathy. The epitheliopathy resolved in all patients 2.4 months after onset. In culture, methotrexate decreased the survival of CECs by inducing apoptosis, increasing oxidative stress, suppressing proliferation, and upregulating inflammatory cytokines. The addition of folinic acid significantly protected the cells from the methotrexate-induced toxicity. Hence, our results suggest that care should be taken to minimize the contact of methotrexate with corneal epithelium during injection, and folic or folinic acid supplementation might be beneficial for preventing corneal complications in patients undergoing intravitreal methotrexate injections.

Rebaudioside A/TPGS mixed nanomicelles as promising nanocarriers for nimodipine ocular delivery

Nimodipine (NMD), a calcium channel blocker, has demonstrated benefits in treating glaucoma. However, its ocular therapeutic application remains limited due to its poor aqueous solubility, which restrains the development of an ophthalmic formulation. Thus, the present study aimed to formulate an NMD micelle ophthalmic solution to enhance the potential of NMD in an ocular topical formulation to treat glaucoma. The NMD micelle ophthalmic solution was formulated with nanocarriers composed of rebaudioside A and D-α-tocopheryl polyethylene glycol 1000 succinate. Spherical mixed micelles were optimized and obtained at a small micelle size 13.429 ± 0.181 nm with a narrow size distribution (polydispersity index 0.166 ± 0.023) and high encapsulation efficiency rate (99.59 ± 0.09%). Compared with free NMD, NMD in micelles had much greater in vitro membrane permeability and antioxidant activity. The NMD micelle ophthalmic solution was well tolerated in rabbit eyes. It profoundly improved the in vivo intraocular permeation of NMD, and in vivo intraocular pressure reduction and improved miosis were also observed. Accordingly, this NMD micelle ophthalmic solution might be a promising ocular formulation to treat glaucoma. Graphical abstract.

Concentration- and Time-Dependent Effects of Benzalkonium Chloride in Human Lung Epithelial Cells: Necrosis, Apoptosis, or Epithelial Mesenchymal Transition

Benzalkonium chloride (BAC), an antimicrobial agent in inhalable medications and household sprays, has been reported to be toxic to pulmonary organs. Although cell membrane damage has been considered as the main cytotoxic mechanism of BAC, its concentration- and time-dependent cellular effects on lung epithelium have not been fully understood. In the present study, human lung epithelial (H358) cells were exposed to 0.2–40 μg/mL of BAC for 30 min or 21 days. Cell membranes were rapidly disrupted by 30 min exposure, but 24 h incubation of BAC (4–40 μg/mL) predominantly caused apoptosis rather than necrosis. BAC (2–4 μg/mL) induced mitochondrial depolarization, which may be associated with increased expression of pro-apoptotic proteins (caspase-3, PARP, Bax, p53, and p21), and decreased levels of the anti-apoptotic protein Bcl-2. The protein expression levels of IRE1α, BiP, CHOP, and p-JNK were also elevated by BAC (2–4 μg/mL) suggesting the possible involvement of endoplasmic reticulum stress in inducing apoptosis. Long-term (7–21 days) incubation with BAC (0.2–0.6 μg/mL) did not affect cell viability but led to epithelial-mesenchymal transition (EMT) as shown by the decrease of E-cadherin and the increase of N-cadherin, fibronectin, and vimentin, caused by the upregulation of EMT transcription factors, such as Snail, Slug, Twist1, Zeb1, and Zeb2. Therefore, we conclude that apoptosis could be an important mechanism of acute BAC cytotoxicity in lung epithelial cells, and chronic exposure to BAC even at sub-lethal doses can promote pulmonary EMT.

Mitochondrial Dysfunctions May Be One of the Major Causative Factors Underlying Detrimental Effects of Benzalkonium Chloride

Benzalkonium chloride (BAC) is currently the most commonly used antimicrobial preservative in ophthalmic solutions, nasal sprays, and cosmetics. However, a large number of clinical and experimental investigations showed that the topical administration of BAC-containing eye drops could cause a variety of ocular surface changes, from ocular discomfort to potential risk for future glaucoma surgery. BAC-containing albuterol may increase the risk of albuterol-related systemic adverse effects. BAC, commonly present in personal care products, in cosmetic products can induce irritation and dose-dependent changes in the cell morphology. The cationic nature of BAC (it is a quaternary ammonium) suggests that one of the major targets of BAC in the cell may be mitochondria, the only intracellular compartment charged negatively. However, the influence of BAC on mitochondria has not been clearly understood. Here, the effects of BAC on energy parameters of rat liver mitochondria as well as on yeast cells were examined. BAC, being a "weaker" uncoupler, potently inhibited respiration in state 3, diminished the mitochondrial membrane potential, caused opening of the Ca2+/Pi-dependent pore, blocked ATP synthesis, and promoted H₂O₂ production by mitochondria. BAC triggered oxidative stress and mitochondrial fragmentation in yeast cells. BAC-induced oxidative stress in mitochondria and yeast cells was almost totally prevented by the mitochondria-targeted antioxidant SkQ1; the protective effect of SkQ1 on mitochondrial fragmentation was only partial. Collectively, these data showed that BAC acts adversely on cell bioenergetics (especially on ATP synthesis) and mitochondrial dynamics and that its prooxidant effect can be partially prevented by the mitochondria-targeted antioxidant SkQ1.

Effects of a prostaglandin F2alpha derivative glaucoma drug on EGF expression and E-cadherin expression in a corneal epithelial cell line

Purpose: We examined the effects of travoprost on cell proliferation-related signals and E-cadherin expression in vitro and in situ in order to obtain evidence to support the hypothesis that topical travoprost impairs the integrity of the corneal epithelium.Methods: A human corneal epithelial cell culture was treated with travoprost (0.4 mg/ml) and/or PD168393 (an EGF receptor inhibitor, 10 μM). The culture was then processed for cell proliferation, an mRNA expression analysis of epidermal growth factor (EGF) and E-cadherin, and protein expression analysis of E-cadherin by immunocytochemistry and Western blotting. The eyes of C57/BL6 mice were incubated in serum-free medium plus travoprost (0.4 mg/ml) and/or PD168393 (10 μM). After being cultured for 24 h, the expression patterns of phospho-EGFR, phospho-ERK, E-cadherin, and Ki67 were immunohistochemically examined in paraffin sections.Results: The addition of travoprost up-regulated EGF mRNA expression and cell proliferation in the corneal epithelial cell culture, and this was cancelled by the addition of PD168393. This FP agonist also decreased E-cadherin expression levels in the cell-cell contact zone, and this was cancelled by the addition of PD168393. In the organ culture, the addition of travoprost to the medium up-regulated the expression of phospho-EGFR and phospho-ERK as well as cell proliferation, and down-regulated the expression of E-cadherin in the corneal epithelium, particularly in basal cells, whereas PD168393 reversed these effects.Conclusions: Travoprost activates epithelial cell proliferation by up-regulating an EGF-related signal in association with the suppression of E-cadherin localization in the cell-cell contact zone. Modulation of the EGF signal may be a strategy to minimize the negative impact of this mitogen on reformation of corneal barrier function during epithelial renewal.

Dose-dependent benzalkonium chloride toxicity imparts ocular surface epithelial changes with features of dry eye disease

PURPOSE

Inclusion of the preservative benzalkonium chloride (BAC) in ophthalmic solutions is prevalent, despite the noted potential for exacerbating dry eye disease (DED). Whilst studies incorporating BAC have assessed its' effects as a mouse model of DED, the impact on limbal epithelia is under-studied. Our investigation aimed to comprehensively assess the impact of different BAC dosing regimens and their suitability as a mouse model of DED.

METHODS

C57BL/6J mice (n = 72) were administered topical BAC (0.05-0.2%) over 7 days. Fluorescein staining, corneal smoothness index, and immuno-histological analyses were applied to determine architectural and cellular changes on the ocular surface following BAC treatment. The effect of BAC (0.0001-0.01%) on cultivated primary mouse corneo-limbal epithelial cells (CLECs) (n = 6) was examined using morphological and functional assays.

RESULTS

Whilst 0.2% BAC induced severe corneal epithelial defects, 0.1% BAC dispensed once daily over 7 days, induced punctate fluorescein staining without detriment to corneal smoothness. Histochemical staining revealed disorganized basal corneal epithelial cells with enlarged cytoplasmic halos. Furthermore, PAS⁺ goblet cells were decreased. BAC treatment also modulated K14 expression and distribution within the limbus. In cultured CLEC, BAC triggered cell contraction and vacuolation, increased LDH release and elevated cell necrosis by 4.1-fold. Concentrations of BAC as low as 0.0001% decreased colony formation.

CONCLUSIONS

This study describes how exposing C57BL/6 mice to BAC induce some clinicopathological features of DED seen in humans, and therefore provides the foundations to explore the consequences on the ocular surface, particularly on limbal epithelia and its' stem cells.

Effects of topical autologous serum on the ocular surface in patients with toxic corneal epitheliopathy induced by anti-glaucoma drugs

PURPOSE

To investigate the effects of topical autologous serum application on the ocular surface in patients with toxic corneal epitheliopathy induced by anti-glaucoma drugs.

METHODS

The patients who had corneal epitheliopathy because of preservative-containing anti-glaucoma eye drops were prospectively enrolled. The epitheliopathy was refractory to preservative-free artificial tear treatment. The patients topically applied 20% autologous serum to the eye eight times per day for 1 month. Baseline and one-month change in symptoms and signs were assessed by the Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time (TFBUT), Schirmer I values, corneoconjunctival staining scores, corneal sensitivity, InflammaDry^® tear immunoassay, and tear cytokine profiles using a bead-based multiplex assay.

RESULTS

A total of ten consecutive patients were enrolled between January and August 2018 and evaluated after one-month treatment with 20% autologous serum eye drops. Significant improvement was observed in symptoms (OSDI scores from 25.5 ± 20.9 to 10.5 ± 12.0; P = .039), TFBUT (from 3.1 ± 1.8 s to 5.4 ± 2.3 s; P = .025), corneoconjunctival staining scores (from 7.7 ± 1.8 to 1.8 ± 1.9 NEI scale; P = .005), corneal sensitivity (from 4.6 ± .9 cm to 5.8 ± .5 cm; P = .013), and metalloproteinase-9 levels (P = .013). There were no significant changes in Schirmer I values and tear cytokine levels on multiplex assays. Treatment-related side effects were not detected.

CONCLUSIONS

Topical instillation of 20% autologous serum is an effective treatment for toxic corneal epitheliopathy associated with anti-glaucoma eye drops.

TRIAL REGISTRATION NUMBER

KCT0003827.