Corneal Epithelial Damage Research Articles

Development and Optimization of an Ex Vivo Model of Corneal Epithelium Damage with 1-Heptanol: Investigating the Influence of Donor Clinical Parameters and MSC-sEV Treatment on Healing Capacity.

To develop and characterize a reproducible human corneal epithelial wound-healing model using 1-heptanol, and to investigate the healing potential of Bone Marrow-derived Mesenchymal Stromal Cell small Extracellular Vesicles (MSC-sEV) and the influence of donor characteristics on epithelial healing. Eighty-eight (n=88) human corneoscleral tissues unsuitable for transplantation were employed. Corneal epithelial damage was induced with 1-heptanol and monitored every 24 hours up to 96 hours using fluorescein and trypan blue staining. Histological assessment was performed on untreated and damaged tissues. Damaged areas were measured with FIJI software, and healing rates were calculated. MSC-sEV were isolated with size exclusion chromatography and characterized for their size, morphology and biomarkers. Their impact on healing was assessed in both in vitro scratch assays on cultured human corneal epithelial cells and on ex vivo 1-heptanol-damaged corneas. Histological analysis revealed detached corneal epithelium in the central area, while other layers remained unaffected. Healing rate peaked at 48 hours post-damage. Trypan blue and Fluorescein staining correlated and the former highlighted a higher initial healing rate than the latter. Diabetic and heart-beating brain-deceased donors showed impaired healing rates. MSC-sEV (79.8 nm, spherical bilayer, positive for TSG101, CD9, CD63, and CD81) significantly improved epithelial wound healing in both in vitro and ex vivo models. 1-heptanol effectively induces reproducible corneal epithelial damage, and the ex vivo organ-cultured human cornea heals the epithelium within 96 hours. Diabetes and donation from heart-beating brain-deceased donors reduce healing capacity. MSC-sEV boost epithelial repair in damaged corneas.

Hyperosmotic stress-induced NLRP3 inflammasome activation via the mechanosensitive PIEZO1 channel in dry eye corneal epithelium.

PIEZO1 modulates the inflammatory response by translating mechanical signals from osmotic pressure into biological processes. This study investigates the functional role of PIEZO1 in activating the NLRP3 inflammasome in corneal epithelial cells under hyperosmotic stress and evaluates its contribution to the pathogenesis of dry eye disease (DED). In the in vitro experiments, immortalized human corneal epithelial cells (HCECs) were cultured under hyperosmotic conditions (450mOsm). For in vivo studies, a dry eye disease mouse model was established by subcutaneous injection of scopolamine (SCOP) in C57BL/6 mice. After successfully inducing the dry eye model, corneal epithelial cell damage was assessed through corneal fluorescein staining scores and TUNEL assays. Protein expression levels were examined via western blotting and immunofluorescence staining, while mRNA expression was analyzed using quantitative RT-PCR. Activation of the NLRP3 inflammasome was evaluated by measuring IL-1β protein cleavage and the formation of ASC speckles. In the DED model, activation of the NLRP3 inflammasome was detected in corneal epithelial cells, along with increased expression of PIEZO1. The PIEZO1-specific agonist Yoda1 induced upregulation of NLRP3 inflammasome-related gene expression and triggered NLRP3 inflammasome activation. Conversely, silencing PIEZO1 using siRNA or inhibiting its activity suppressed hyperosmotic stress-induced changes in NLRP3 inflammasome-related gene expression and activation. In vivo, PIEZO1 inhibition effectively prevented NLRP3 inflammasome activation in corneal epithelial cells and restored the damaged phenotype associated with dry eye disease. Hyperosmotic stress-induced activation of the NLRP3 inflammasome in corneal epithelial cells is mediated through PIEZO1 activation. The identification of PIEZO1's role in this DED-related pathophysiological response highlights its potential as a therapeutic target for mitigating inflammation in clinical settings.

Investigation of the Ocular Response and Corneal Damage Threshold of Exposure to 28 GHz Quasi-millimeter Wave Exposure.

Electromagnetic radiation energy at millimeter wave frequencies, typically 30 GHz to 300 GHz, is ubiquitously used in society in devices for telecommunications; radar and imaging systems for vehicle collision avoidance, security screening, and medical equipment; scientific research tools for spectroscopy; industrial applications for non-destructive testing and precise measurement; and military and defense applications. Understanding the biological effects of this technology is essential. We have been investigating ocular responses and damage thresholds comparing various frequencies using rabbit eyes and dedicated experimental apparatus. In this study we investigated the 28 GHz quasi-millimeter wave band (wavelength: 10.7 mm), a candidate for 5G communication. Similar to millimeter wave frequencies, ocular damage from exposure to 28 GHz for 6 min (400 mW cm-2) included corneal epithelial damage, corneal edema, and opacity. The incident power density threshold, indicating a 50% probability of ocular damage from exposure for 6 min, was found to be 359 mW cm-2 for 28 GHz. Comparing the ocular exposure area for various millimeter wave frequencies (40, 75, 95 GHz) and 28 GHz quasi-millimeter waves using a thermosensitive liquid crystal capsule, we found that for millimeter waves, even at identical incident power densities, the ocular exposure area decreases as the frequency increases (lens effect). However, this lens effect was not observed at 28 GHz, where the entire anterior segment area was exposed to radio waves.

Destructive and protective effects and therapeutic targets of IL-36 family cytokines in dry eye disease.

To explore the destructive and protective effects and therapeutic targets of IL-36 cytokines in dry eye disease using a murine dry eye model. A dry eye model was established in C57BL/6 mice exposed to desiccating stress (DS) with untreated mice as controls. A topical challenge model was performed in normal mice with exogenous rmIL-36α, rhIL-38 and 2% ectoine, or PBS vehicle. IL-36 cytokine expression was assessed by RT-qPCR and immunofluorescent (IF) staining. Corneal epithelial damage was evaluated by corneal smoothness score, Oregon Green Dextran (OGD) fluorescent staining, and tight junction barrier. All members of the IL-36 family were expressed by murine ocular surface epithelium. The expression of IL-36α and IL-36γ was upregulated while IL-38 and IL-36RN were down regulated in ocular surface of dry eye mice. A topical challenge of rmIL-36α directly destructed corneal surface with distorted smoothness, increased OGD uptake and IF intensity, and disrupted tight junction proteins ZO-1 and occludin. Co-application with rhIL-38 prevented all these corneal damages by rmIL-36α. Ectoine treatment reversed the pathological expression pattern of IL-36 cytokines, protected corneal epithelium from defects, and restored the tight junction barrier in DS mice, and even prevented corneal damage by rmIL-36α. Our findings demonstrate the upregulated pro-inflammatory agonists IL-36α and IL-36γ with downregulated antagonists IL-38 and IL-36RA in dry eye model, which provides a previously unknown mechanism and therapeutic targets in dry eye disease. The therapeutic efficacy of ectoine may be through reversing the pathological alteration of IL-36 cytokines in dry eye mice.

CD4+ T cells drive corneal nerve damage but not epitheliopathy in an acute aqueous-deficient dry eye model

Dry eye disease (DED) is characterized by a dysfunctional tear film in which the corneal epithelium and its abundant nerves are affected by ocular desiccation and inflammation. Although adaptive immunity and specifically CD4+ T cells play a role in DED pathogenesis, the exact contribution of these cells to corneal epithelial and neural damage remains undetermined. To address this, we explored the progression of a surgical DED model in wild-type (WT) and T cell-deficient mice. We observed that adaptive immune-deficient mice developed all aspects of DED comparably to WT mice except for the absence of functional and morphological corneal nerve changes, nerve damage-associated transcriptomic signature in the trigeminal ganglia, and sustained tear cytokine levels. Adoptive transfer of CD4+ T cells from WT DED mice to T cell-deficient mice reproduced corneal nerve damage but not epitheliopathy. Conversely, T cell-deficient mice reconstituted solely with naïve CD4+ T cells developed corneal nerve impairment and epitheliopathy upon DED induction, thus replicating the WT DED phenotype. Collectively, our data show that while corneal neuropathy is driven by CD4+ T cells in DED, corneal epithelial damage develops independently of the adaptive immune response. These findings have implications for T cell-targeting therapies currently in use for DED.

Morphological aberration of corneal nerves in hyposecretory dry eye guinea pigs.

Dry eye, a common ocular surface disease associated with tear film instability and corneal impairment, is frequently accompanied by ocular discomfort and pain. Recent research has shown that corneal nerve dysfunction may play a role in certain pathologies of dry eye; however, the details remain unclear. To clarify the aberration in corneal nerves underlying sensory abnormalities, in addition to corneal impairment in dry eye, we examined the morphological alterations of nerve fibers in the corneas excised from guinea pigs with dry eye, where the lacrimal glands were surgically excised. Guinea pigs with dry eye exhibited reduced tear volume, increased spontaneous blink frequency, and corneal epithelial damage. Simultaneously, the subbasal nerve plexus in the cornea visualized using an anti-tubulin βIII antibody partially outgrew and became convoluted. The morphology of peptidergic nerves containing calcitonin gene-related peptide, which may function as a polymodal nociceptor, was also altered. These results indicate that guinea pigs with excised lacrimal glands can serve as useful tools for investigating the neuronal mechanisms underlying corneal pathology in dry eyes. Additionally, chronic tear deficiency may considerably alter nerve structure, including peptidergic nerves in the cornea, accompanied by epithelial damage and increased blink frequency.

Clinical analysis of 124 cases of mycoplasma pneumoniae infection with conjunctivitis in children

Objective: To explore the distribution characteristics of symptoms and signs of respiratory mycoplasma pneumoniae infection complicated with conjunctivitis in children of different age groups. Methods: A retrospective case series study was conducted. Data of children who were treated in Beijing Children's Hospital Affiliated to Capital Medical University from September 20, 2023 to November 30, 2023, had definite mycoplasma pneumoniae infection as confirmed by mycoplasma pneumoniae nucleic acid or mycoplasma pneumoniae IgM antibody test, and had conjunctivitis as the first diagnosis in ophthalmology department were continuously collected. The included children were divided into infant group (age<4 years), preschool group (age 4 to 6 years), and school-age group (age>6 years) for analysis. Information such as the time of ocular symptoms onset, the time of systemic symptoms onset, conjunctival sac secretion, subconjunctival hemorrhage, conjunctival congestion, corneal epithelial damage, co-infection with other pathogens, and treatment of all children was collected and compared among children of different age groups. Results: During this period, there were a total of 31 133 children with positive laboratory test results for mycoplasma pneumoniae. Among them, 835 children visited the ophthalmology department during the same period, and 124 cases (229 eyes) had conjunctivitis as the first diagnosis. The age was (5.43±2.83) years, including 72 males and 52 females. There were 37 cases (69 eyes) in the infant group, 48 cases (92 eyes) in the preschool group, and 39 cases (68 eyes) in the school-age group. Among the 229 eyes, 179 eyes (78.16%) had conjunctival secretion, all manifested as mucopurulent secretion; 12 eyes (5.24%) had corneal epithelial defect; and 26 eyes (11.35%) had subconjunctival hemorrhage. There was 1 eye (1.45%) with subconjunctival hemorrhage in the infant group, 16 eyes (17.39%) in the preschool group, and 9 eyes (13.24%) in the school-age group. The proportion of subconjunctival hemorrhage in the preschool group and school-age group was higher than that in the infant group (both P<0.05). Thirty-nine cases (31.45%) were found to have co-infection with viruses in laboratory tests, including influenza A virus, adenovirus, respiratory syncytial virus, and coxsackievirus. The proportion of children in all age groups with ocular symptoms first was higher than that with systemic symptoms first. There was no statistically significant difference among children in the three age groups in terms of whether there was conjunctival secretion, whether there was corneal epithelial damage, whether there was co-infection with viruses, and the interval between ocular symptoms and systemic symptoms onset (all P>0.05). Conclusions: The characteristic ocular manifestations of children with mycoplasma pneumoniae infection complicated with conjunctivitis are conjunctival congestion and subconjunctival hemorrhage, and the signs are more obvious in preschool children. The conjunctival sac secretion of such children with conjunctivitis is mostly manifested as mucopurulent. Ocular symptoms may be the first manifestation of mycoplasma pneumoniae infection.

Exposure to particulate matter (PM2.5) weakens corneal defense by downregulating thrombospondin-1 and tight junction proteins

BackgroundFine particulate matter (PM2.5) induces ocular surface toxicity through pyroptosis, oxidative stress, autophagy, and inflammatory responses. However, the precise molecular pathways through which PM2.5 causes corneal damage remain unclear. This study aims to investigate the underlying mechanisms by exposing human corneal epithelial cells (HCECs) to PM2.5. MethodsAfter the morphology and chemical composition analysis of the PM samples, we conducted both in vivo and in vitro experiments to investigate PM2.5-induced corneal epithelial damage. We assessed corneal barrier function in HCECs using transepithelial electrical resistance (TEER) assays. To explore the molecular mechanisms of PM2.5-induced corneal epithelial damage, we performed whole-transcriptome resequencing, quantitative RT-PCR, and western blotting in vitro. In addition, we analyzed mouse corneas exposed to concentrated ambient PM2.5 through immunofluorescence staining to observe the resulting changes in corneal epithelial protein expression in vivo. ResultsOur results showed significant impairment of corneal epithelial barrier function in PM2.5-treated HCECs, as indicated by decreased TEER values. The expression of thrombospondin-1 (THBS1) and claudin-1, both key factors for maintaining corneal epithelial barrier integrity, was markedly reduced at the gene and protein levels in both in vitro and in vivo PM2.5 exposure models. Moreover, the levels of tight junction-associated proteins, including occludin, zonula occludens-1 (ZO-1) and ZO-2, essential components of the corneal epithelial barrier, were significantly diminished in PM2.5-treated HCECs. ConclusionPM2.5 exposure leads to corneal epithelium damage by disrupting tight junction proteins and THBS1 expression. These findings provide insight into potential pathways for PM2.5-induced ocular toxicity and underscore the need for protective strategies against such environmental pollutants.

A Selective Melatonin 2 Receptor Agonist, IIK7, Relieves Blue Light-Induced Corneal Damage by Modulating the Process of Autophagy and Apoptosis

This study aims to investigate the effect of the selective MT2 receptor agonist, IIK7, on corneal autophagy and apoptosis, aiming to reduce corneal epithelial damage and inflammation from blue light exposure in mice. Eight-week-old C57BL/6 mice were divided into BL-exposed (BL) and BL-exposed with IIK7 treatment (BL + IIK7 group). Mice underwent blue light exposure (410 nm, 100 J) twice daily with assessments at baseline and on days 3, 7, and 14. Corneal samples were analyzed for MT2 receptor expression, autophagy markers (LC3-II and p62), and apoptosis indicators (BAX expression and TUNEL assay). Then, mice were assigned to normal control, BL, and BL + IIK7. Ocular surface parameters, including corneal fluorescein staining scores, tear volume, and tear film break-up time, were evaluated on days 7 and 14. On day 14, reactive oxygen species (ROS) levels and CD4+ IFN-γ+ T cells percentages were measured. The BL group exhibited higher LC3-II and p62 expression, while the BL + IIK7 group showed reduced expression (p &lt; 0.05). The TUNEL assay showed reduced apoptosis in the BL + IIK7 group compared to the BL group. ROS levels were lower in the BL + IIK7 group. The BL + IIK7 group showed improved ocular surface parameters, including decreased corneal fluorescein staining and increased tear volume. The percentages of CD4+ IFN-γ+ T cells indicated reduced inflammatory responses in the BL + IIK7 group. The MT2 receptor agonist IIK7 regulates corneal autophagy and apoptosis, reducing corneal epithelial damage and inflammation from blue light exposure.

Mineralocorticoid receptor expression and the effects of the mineralocorticoid receptor antagonist spironolactone in a murine model of graft-versus-host disease

PurposeThe topical administration of spironolactone, a mineralocorticoid receptor antagonist (MRA) improves dry eye symptoms in patients with ocular graft-versus-host disease (GVHD); however, the detailed mechanism remains unclear. This study aimed to investigate the effects of spironolactone eyedrops on the ocular surface using a chronic GVHD (cGVHD) mouse model and to determine the expression of the mineralocorticoid receptor (MR). MethodsA cGVHD mouse model was established by allogeneic bone marrow transplantation (BMT) from B10.D2 mice to BALB/c mice. Subsequently, cGVHD mice were treated with either 0.005 % spironolactone or vehicle eyedrops. The eyelids, cornea and conjunctiva of the recipients were analyzed at 4-week intervals post-BMT in both groups. ResultsSigns of ocular GVHD, such as corneal epithelial damage, depletion of meibomian glands, and inflammatory cell infiltration onto the ocular surface, were significantly decreased in cGVHD mice treated with spironolactone eyedrops. The expression of the MR NR3C2 in the corneal and conjunctival epithelia was significantly increased in cGVHD mice. HSP47+NR3C2+ MR-expressing fibroblasts, CD45+NR3C2+ MR-expressing leukocytes, and CD4+NR3C2+ MR-expressing T cells infiltrated the ocular surface tissue of cGVHD mice significantly more than that of syngeneic controls. ConclusionsMR expression is increased in epithelial cells, fibroblasts, and T cells in a murine cGVHD model, whereas MRA and spironolactone eyedrops could attenuate the severity of ocular GVHD. These findings suggest that MR signaling partially contributes to the development of ocular GVHD in this mouse model.

Therapeutic Potential of Crocin and Nobiletin in a Mouse Model of Dry Eye Disease: Modulation of the Inflammatory Response and Protection of the Ocular Surface.

Dry eye disease (DED) is a multifactorial condition characterized by ocular surface inflammation, tear film instability, and corneal epithelial damage. Current treatments often provide temporary relief without addressing the underlying inflammatory mechanisms. This study examined the therapeutic potential of crocin and nobiletin, two naturally derived compounds with well-known antioxidant and anti-inflammatory properties, in a mouse model of DED induced by lacrimal gland excision (LGE). Thirty female Balb/c mice were divided into five groups (n = 6 each): Control (sham surgery), untreated DED, nobiletin-treated DED (32.75 µM), crocin-treated DED (34 µM), and 1% betamethasone-treated DED. Treatments were administered three times daily for 28 days. Ocular tissues were evaluated using Hematoxylin and Eosin (H&E) staining and fluorescein staining. Conjunctival inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and tumor necrosis factor-alpha (TNF-α), were measured by enzyme-linked immunosorbent assay (ELISA). Histological analysis showed that the crocin and nobiletin treatment groups exhibited reduced epithelial disruption, keratinization, and inflammatory cell infiltration compared to the untreated DED group. The ELISA assay revealed that both compounds efficiently inhibited the production of the pro-inflammatory cytokines IL-6, TNF-α, and IL-1β, which are key mediators of DED pathogenesis. Fluorescein staining further confirmed the protective impact of crocin and nobiletin on corneal epithelial integrity. Moreover, the anti-inflammatory and epithelial-preserving effects of these compounds were comparable to those of the corticosteroid betamethasone. Overall, these findings suggest that crocin and nobiletin have therapeutic potential for DED management by modulating inflammatory responses and enhancing ocular surface healing. These naturally derived compounds offer promising avenues for the development of safer and more effective treatments for this challenging condition. However, further investigations, including clinical trials, are essential to elucidate the underlying mechanisms of action and optimize therapeutic approaches.

Preventative Effect of Topical Rebamipide Against Corneal Epithelium Disorders Caused by Diclofenac Sodium.

Purpose: This study aimed to investigate the relationship between diclofenac sodium ophthalmic solution (DFNa) and corneal epithelial cell damage and to evaluate the preventive effect of rebamipide (RBM) on it. Methods: DFNa, DFNa/preservative-free (PF), or 0.5% chlorobutanol (CB) solution was instilled into the conjunctival sac of a normal rabbit eye, and corneal resistance measurement (using a corneal resistance device [CRD]) was performed 120 min after the end of instillation. Then, fluorescent staining (FL), corneal tissue staining (hematoxylin and eosin [H&E]), and immunostaining (zona occlusion-1) were performed (RBM-untreated group). However, RBM was instilled into the eyes of another group of normal rabbits, followed by each of the solutions; 120 min after the end of instillation, all evaluations were performed for this group (RBM treatment group). Results: Using the CRD method, in the RBM-untreated group, corneal resistance (CR; %) was found to be significantly reduced in DFNa (79.9 ± 19.4%), DFNa/PF (89.1 ± 17.3%), and 0.5% CB (83.8 ± 10.6%). In addition, DFNa and 0.5% CB solutions showed positive staining in the FL staining method. In the H&E staining method, some clear voids were observed in the outermost layer of the cornea using DFNa and 0.5% CB solutions. However, corneal epithelial damage was suppressed in the RBM treatment group. ZO-1 immunostaining in DFNa and 0.5% CB solutions revealed discontinuous localization of ZO-1 at the cell periphery. Conclusions: RBM eye drops were effective in preventing corneal epithelial damage caused by DFNa eye drops, and CB was considered to be the main causative agent of this damage.

Effects of High Temperature and High Humidity on the Degree of Ocular Damage Caused by 60 GHz Millimeter Wave Exposure.

Millimeter waves (MMW) are pervasive in society; however, studies on the biological effects of MMW exposure are usually performed in laboratory settings not reflecting global environmental diversity. We investigated the effects of a 6-min exposure to 60 GHz MMW (wavelength, 5.0 mm) at incident power densities of 200 and 300 mW cm-2 in eyes (exposed right eyes vs. unexposed left eyes) under various ambient temperature/relative humidity environments (24 °C/50%, 45 °C/20%, and 45 °C/80%) using an in vivo rabbit model. Correlations were examined with adverse ocular events, including corneal epithelial damage (assessed using fluorescein staining), corneal opacity (evaluated by slit-lamp microscopy), and corneal thickness (measured via optical coherence tomography). Our findings indicate that higher temperatures and humidity tend to exacerbate MMW-induced ocular damage, albeit not significantly in the present study. Further research with a larger sample size is warranted. Incident power density emerged as a factor that was directly linked to the ocular damage threshold. High ambient temperature and humidity tended to exacerbate ocular damage from MMW exposure, although the effect was secondary. Ocular damage in a high-temperature (45 °C), high-humidity (80%) environment was increased to the same extent as that by incident power density increased by approximately 100 mW cm-2 in an ocular damage model in a standard environment (24 °C, 50%). In a high-humidity environment, the internal ocular tissue temperature increased at a high ambient temperature of 45 °C, suggesting that the eyeball may respond differently compared to other tissues.

Improvement of corneal epithelial damage after switching from the concomitant use of brinzolamide and brimonidine to a brinzolamide/brimonidine fixed-dose combination.

To assess the effectiveness of switching from the concomitant use of brinzolamide 1% (BZM) and brimonidine 0.1% (BMD) to a BZM/BMD fixed-dose combination (BBFC) for the reduction of corneal epithelial damage. Retrospective cohort study. This study involved 52 eyes of 52 glaucoma patients (26 women, 26 men; mean age: 67.0 ± 14.0 years) followed for more than 3 months after being switched from concomitant BZM and BMD to BBFC. Superficial punctate keratitis (SPK) was assessed by fluorescein staining according to the National Eye Institute classification, with the cornea divided into 5 areas: center, superior, nasal, temporal, and inferior. SPK density was graded as 0 (no SPK), 1 (separate SPK), 2 (moderately dense SPK), and 3 (high SPK with overlapping lesions). SPK scores and intraocular pressure (IOP) at pre switching to BBFC (pre-BBFC) and at 3-months post switching to BBFC (post-BBFC) were then compared using the Wilcoxon signed-rank test. At pre-BBFC and post-BBFC, respectively, mean IOP was 12.4 ± 2.5 and 12.4 ± 2.7 mmHg, thus illustrating no significant difference in IOP between pre and post switch (p = 0.924), and the mean SPK score for center, superior, nasal, temporal, and inferior was 0.06 ± 0.24, 0.04 ± 0.19, 0.52 ± 0.67, 0.15 ± 0.36, and 0.92 ± 0.74, and 0.04 ± 0.19, 0.02 ± 0.14, 0.37 ± 0.56, 0.04 ± 0.19, and 0.75 ± 0.62, thus clearly showing a significant reduction in SPK scores for the nasal, temporal, and inferior areas at post-BBFC compared to those at pre-BBFC (p < 0.05). Our findings reveal that compared with the concomitant use of BZM and BMD, BBFC is effective in reducing corneal epithelial damage.

Diesel exhaust exposure induced squamous metaplasia of corneal epithelium via yes-associated protein activation

Atmospheric pollution has been demonstrated to be associated with ocular surface diseases characterized by corneal epithelial damage, including impaired barrier function and squamous metaplasia. However, the specific mechanisms underlying the impact of atmospheric pollution on corneal damage are still unknow. To address this gap in knowledge, we conducted a study using a whole-body exposure system to investigate the detrimental effects of traffic-related air pollution, specifically diesel exhaust (DE), on corneal epithelium in C57BL/6 mice over a 28-day period. Following DE exposure, the pathological alterations in corneal epithelium, including significant increase in corneal thickness and epithelial stratification, were observed in mice. Additionally, exposure to DE was also shown to disrupt the barrier functions of corneal epithelium, leading to excessive proliferation of basal cells and even causing squamous metaplasia in corneal epithelium. Further studies have found that the activation of yes-associated protein (YAP), characterized by nuclear translocation, may play a significant role in DE-induced corneal squamous metaplasia. In vitro assays confirmed that DE exposure triggered the YAP/β-catenin pathway, resulting in squamous metaplasia and destruction of barrier functions. These findings provide the preliminary evidence that YAP activation is one of the mechanisms of the damage to corneal epithelium caused by traffic-related air pollution. These findings contribute to the knowledge base for promoting eye health in the context of atmospheric pollution.

Clinical Efficacy of 2% Rebamipide in Patients With Video Display Terminal-Associated Dry Eye Disease: A Prospective, Randomized, Double-Blinded Study.

To compare the effects of 2% rebamipide clear solution and 0.1% sodium hyaluronate eye drops in patients with visual display terminal (VDT)-related dry eye disease (DED). Prospective, randomized, double-blinded Study. This was a prospective, double-blind, and randomized controlled study. Patients with VDT-related DED were randomly allocated to a 2% rebamipide (REB) group or a 0.1% sodium hyaluronate (HYA) group (4 times/day for 4 weeks). The ocular surface disease index (OSDI), dry eye questionnaire-5 (DEQ-5), Placido disk-tear film analyzer, fluorescein-stained tear break-up time (FBUT), ocular surface staining score, and Schirmer 1 test were examined before and after the instillation of drug. A total of 56 eyes of 28 patients (28 eyes of 14 patients in each group) were included. There were no significant differences in the baseline data. The OSDI, DEQ-5, FBUT, and conjunctival erosion scores improved significantly in both groups after treatment. In the REB group, corneal staining and bulbar nasal redness scores also improved significantly after treatment ( P <0.001 and 0.036, respectively), whereas no significant differences were found in these parameters in the HYA group ( P =0.326 and 0.118, respectively). The REB group showed a significantly larger decrease in the corneal staining score than the HYA group ( P =0.016). No adverse reactions were observed. A 2% rebamipide clear solution effectively improved the symptoms and signs in patients with VDT-related DED and was superior to 0.1% sodium hyaluronate ophthalmic solution in improving corneal epithelial damage, making it a safe and effective treatment option for VDT-related DED.

Blast injury: Impact to the cornea

Visual disorders are common even after mild traumatic brain injury (mTBI) or blast exposure. The cost of blast-induced vision loss in civilians, military personnel, and veterans is significant. The visual consequences of blasts associated with TBI are elusive. Active military personnel and veterans report various ocular pathologies including corneal disorders post-combat blasts. The wars and conflicts in Afghanistan, Iraq, Syria, and Ukraine have significantly increased the number of corneal and other ocular disorders among military personnel and veterans. Binocular vision, visual fields, and other visual functions could be impaired following blast-mediated TBI. Blast-associated injuries can cause visual disturbances, binocular system problems, and visual loss. About 25% of veterans exposed to blasts report corneal injury. Blast exposure induces corneal edema, corneal opacity, increased corneal thickness, damage of corneal epithelium, corneal abrasions, and stromal and endothelial abnormality including altered endothelial density, immune cell infiltration, corneal neovascularization, Descemet membrane rupture, and increased pain mediators in animal models and the blast-exposed military personnel including veterans. Immune response exacerbates blast-induced ocular injury. TBI is associated with dry eyes and pain in veterans. Subjects exposed to blasts that cause TBI should undergo immediate clinical visual and ocular examinations. Delayed visual care may lead to progressive vision loss, lengthening/impairing rehabilitation and ultimately may lead to permanent vision problems and blindness. Open-field blast exposure could induce corneal injuries and immune responses in the cornea. Further studies are warranted to understand corneal pathology after blast exposure. A review of current advancements in blast-induced corneal injury will help elucidate novel targets for potential therapeutic options. This review discusses the impact of blast exposure-associated corneal disorders.

Mesenchymal stem cell-based adjunctive therapy for Pseudomonas aeruginosa-induced keratitis: A proof-of-concept in-vitro study

PurposePseudomonas aeruginosa-induced keratitis is one of the most severe and challenging forms of corneal infection, owing to its associated intense inflammatory reactions leading to corneal necrosis and dense corneal scar with loss of vision. Since mesenchymal stem cells (MSCs) are reported to possess antimicrobial and immunomodulatory properties, they can be tested as an adjuvant treatment along with the antibiotics which are the current standard of care. This study aims to investigate the anti-bacterial and immunomodulatory roles of human bone marrow MSC-derived conditioned medium (MSC-CM) in P. aeruginosa-infected human corneal epithelial cells (HCECs) in vitro. MethodsThe effect of MSC-CM on the growth of clinical isolates of P. aeruginosa was evaluated by colony-forming unit assay. The expression of inflammatory cytokines (IL-6 and TNF-α) and an antimicrobial peptide (Lipocalin 2) in lipopolysaccharide-treated MSCs and HCECs was analyzed through ELISA. Corneal epithelial repair following infection with P. aeruginosa was studied through scratch assay. ResultsCompared to control (P. aeruginosa (5*105) incubated in DMEM (1 ml) at 37 °C for 16 h), MSC-CM significantly: i) inhibits the growth of P. aeruginosa (159*109 vs. 104*109 CFU/ml), ii) accelerates corneal epithelial repair following infection with P. aeruginosa (9% vs. 24% closure of the wounded area after 12 h of infection), and iii) downregulates the lipopolysaccharide-induced expression of IL-6, TNF-α and Lipocalin 2 in HCECs. A combination of MSC-CM with an antibiotic, Ciprofloxacin moderately regulated the expression of IL-6, TNF-α, and Lipocalin 2. ConclusionMSC-CM holds promise as an adjunctive therapeutic approach for P. aeruginosa-induced corneal epithelial damage.

In‐vivo corneal collagen crosslinking using ruthenium and visible light

Aims/Purpose: Corneal collagen cross‐linking (CXL) treatment is widely applied to halt the progression of ectatic diseases such as keratoconus. Unfortunately, the standard CXL procedure based on riboflavin and UV‐A light can only be applied to cornea thicker than 400 μm and results in frequent complications, such as corneal haze and endothelial damage [1]. This study investigates a new CXL procedure based on ruthenium, which is a water‐soluble photoinitiator and visible light (430 nm) in vivo.Methods: For the CXL procedure, tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+), an SPS solution was applied to the rat's cornea and exposed to blue light. After the crosslinking procedure, observations were made for corneal opacity, corneal neovascularization, limbal neovascularization and corneal epithelial damage. Furthermore, the corneas were isolated for histopathological examination, cell viability and SEM analysis, and the results were compared with the conventional riboflavin/UV‐A crosslinking approach.Results: Crosslinked corneas with ruthenium‐based CXL approach showed significantly improved scoring in corneal opacity, corneal neovascularization, limbal neovascularization and corneal wound healing as compared to the standard riboflavin and UVA‐based CXL procedure. Histopathological analysis and cell viability revealed ruthenium to be nontoxic and create more bonds between collagen fibrils when observed under scanning electron microscopy.Conclusions: In this in vivo study, the ruthenium and visible light‐based crosslinking approach proved to be non‐toxic and a faster alternative to the conventional riboflavin and UVA‐based CXL method. We foresee that ruthenium visible light‐based crosslinking treatment could potentially change the treatment modality in keratoconus patients in a clinical setting.Funding Information: This work is supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK) under GrantARDEB‐219S349.

Autologous serum eye drops for patients with dry eye disease: a systematic review and meta-analysis of randomized controlled trials.

Dry eye disease (DED) is highly prevalent worldwide, leading to increased medical costs, economic burdens on families and society, and a diminished quality of life for patients. The utilization of autologous serum eye drops (ASEDs) for the treatment of DED is progressively rising. To further evaluate the efficacy and safety of ASEDs in the treatment of DED. A thorough search for randomized controlled trials (RCTs) was conducted across eight databases, including PubMed, EMBASE, the Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang, SinoMed, and VIP. This search encompassed the inception of each database up to April 1, 2024, with a specific focus on identifying RCTs evaluating the efficacy and safety of ASEDs for the treatment of DED. Data analysis was conducted utilizing Stata 15.0 software and the Cochrane Risk of Bias Assessment Tool was utilized to appraise the literature's quality. The study encompassed 12 RCTs. In comparison to the use of artificial tears (AT), patients diagnosed with DED who utilized ASEDs displayed elevated the Schirmer test (ST) scores [WMD = 2.35, 95% CI (1.45, 3.24), p < 0.001] and tear-film breakup time (TBUT) scores [WMD = 2.83, 95% CI (2.27, 3.39), p < 0.001], decreased Corneal fluorescence staining (CFS) scores [SMD = -2.11, 95% CI (-3.07, -1.15), p < 0.001] and the Ocular Surface Disease Index (OSDI) scores [WMD = -10.54, 95% CI (-13.31, -7.77), p < 0.001], and experienced a reduced frequency of adverse events [RR = 0.36, 95% CI (0.13, 0.99), p = 0.048]. In this study, ASEDs had been shown to enhance tear secretion, extend tear film break-up time, mitigate corneal epithelial damage, ameliorate OSDI scores, and exhibit greater safety compared to AT.