Insulin eye drops improve corneal wound healing in STZ-induced diabetic mice by regulating corneal inflammation and neuropeptide release.

INTRODUCTION: In recent years, insulin eye drops have attracted increasing attention from researchers and ophthalmologists. The aim of this study was to investigate the efficacy and possible mechanism of action of insulin eye drops in diabetic mice with corneal wounds. METHODS: A type 1 diabetes model was induced, and a corneal epithelial injury model of 2.5 mm was established. We used corneal fluorescein staining, hematoxylin-eosin (H-E) staining and the Cochet-Bonnet esthesiometer to examine the process of wound healing. Subsequently, the expression levels of Ki-67, IL-1ß, ß3-tubulin and neuropeptides, including substance P (SP) and calcitonin gene-related peptide (CGRP), were examined at 72 h after corneal injury. RESULTS: Fluorescein staining demonstrated an acceleration of the recovery of corneal epithelial injury in diabetic mice compared with the saline treatment, which was further evidenced by the overexpression of Ki-67. Moreover, 72 h of insulin application attenuated the expression of inflammatory cytokines and neutrophil infiltration. Remarkably, the results demonstrated that topical insulin treatment enhanced the density of corneal epithelial nerves, as well as neuropeptide SP and CGRP release, in the healing cornea via immunofluorescence staining. CONCLUSIONS: Our results indicated that insulin eye drops may accelerate corneal wound healing and decrease inflammatory responses in diabetic mice by promoting nerve regeneration and increasing levels of neuropeptides SP and CGRP.

Transient plasma membrane disruption induced calcium waves in mouse and human corneal epithelial cells.

The purpose of this study was to examine transient plasma membrane disruptions (TPMDs) and TPMD-induced Ca++ waves (TPMD Ca++ Wvs) in human and mouse corneal epithelium (HCEC and MCEC). A multi-photon microscope was used to create laser-induced TPMDs in single cultured cells and in intact ex vivo and in vivo MCECs and ex vivo human cornea rim HCECs. Eye rubbing-induced TPMDs were studied by gentle rubbing with a cotton tipped applicator over a closed eyelid in ex vivo and in vivo MCECs. Ca++ sources for TPMD-induced Ca++ waves were explored using Ca++ channel inhibitors and Ca++-free media. TPMDs and TPMD Ca++ Wvs were observed in all cornea epithelial models examined, often times showing oscillating Ca++ levels. The sarcoplasmic reticulum Ca++ ATPase inhibitors thapsigargin and CPA reduced TPMD Ca++ Wvs. TRP V1 antagonists reduced TPMD Ca++ Wvs in MCECs but not HCECs. Ca++-free medium, 18α-GA (gap junction inhibitor), apyrase (hydrolyzes ATP), and AMTB (TRPM8 inhibitor) did not affect TPMD Ca++ Wvs. These results provide a direct demonstration of corneal epithelial cell TPMDs and TPMDs in in vivo cells from a live animal. TPMDs were observed following gentle eye rubbing, a routine corneal epithelial cell mechanical stress, indicating TPMDs and TPMD Ca++ Wvs are common features in corneal epithelial cells that likely play a role in corneal homeostasis and possibly pathophysiological conditions. Intracellular Ca++ stores are the primary Ca++ source for corneal epithelial cell TPMD Ca++ Wvs, with TRPV1 Ca++ channels providing Ca++ in MCECs but not HCECs. Corneal epithelial cell TPMD Ca++ Wv propagation is not influenced by gap junctions or ATP.

NEAT1 Deficiency Promotes Corneal Epithelial Wound Healing by Activating cAMP Signaling Pathway.

Purpose: This study aimed to investigate the role of the long non-coding RNA (lncRNA) NEAT1 in corneal epithelial wound healing in mice. Methods: The central corneal epithelium of wild-type (WT), MALAT1 knockout (M-KO), NEAT1 knockout (N-KO), and NEAT1 knockdown (N-KD) mice was scraped to evaluate corneal epithelial and nerve regeneration rates. RNA sequencing of the corneal epithelium from WT and N-KO mice was performed 24 hours after debridement to determine the role of NEAT1. Quantitative PCR (qPCR) and ELISA were used to confirm the bioinformatic analysis. The effects of the cAMP signaling pathway were evaluated in N-KO and N-KD mice using SQ22536, an adenylate cyclase inhibitor. Results: Central corneal epithelial debridement in N-KO mice significantly promoted epithelial and nerve regeneration rates while suppressing inflammatory cell infiltration. Furthermore, the expression of Atp1a2, Ppp1r1b, Calm4, and Cngb1, which are key components of the cAMP signaling pathway, was upregulated in N-KO mice, indicative of its activation. Furthermore, the cAMP pathway inhibitor SQ22536 reversed the accelerated corneal epithelial wound healing in both N-KO and N-KD mice. Conclusions: NEAT1 deficiency contributes to epithelial repair during corneal wound healing by activating the cAMP signaling pathway, thereby highlighting a potential therapeutic strategy for corneal epithelial diseases.

Single nuclei transcriptomics of the in situ human limbal stem cell niche.

The corneal epithelium acts as a barrier to pathogens entering the eye; corneal epithelial cells are continuously renewed by uni-potent, quiescent limbal stem cells (LSCs) located at the limbus, where the cornea transitions to conjunctiva. There has yet to be a consensus on LSC markers and their transcriptome profile is not fully understood, which may be due to using cadaveric tissue without an intact stem cell niche for transcriptomics. In this study, we addressed this problem by using single nuclei RNA sequencing (snRNAseq) on healthy human limbal tissue that was immediately snap-frozen after excision from patients undergoing cataract surgery. We identified the quiescent LSCs as a sub-population of corneal epithelial cells with a low level of total transcript counts. Moreover, TP63, KRT15, CXCL14, and ITGß4 were found to be highly expressed in LSCs and transiently amplifying cells (TACs), which constitute the corneal epithelial progenitor populations at the limbus. The surface markers SLC6A6 and ITGß4 could be used to enrich human corneal epithelial cell progenitors, which were also found to specifically express the putative limbal progenitor cell markers MMP10 and AC093496.1.

Thickness of anterior sclera and corneal layers in systemic sclerosis.

PURPOSE: To evaluate the thickness of anterior sclera and corneal layers in patients with systemic sclerosis. METHODS: The present cross-sectional study included 41 patients with systemic sclerosis and 41 age- and gender-matched healthy controls. The study and control groups were compared in terms of the thickness of anterior sclera, corneal epithelium, Bowman's layer, corneal stroma, and Descemet's membrane-endothelium complex. The thickness measurements were obtained using the anterior segment module of spectral-domain optical coherence tomography. RESULTS: The thickness of anterior sclera, corneal epithelium, Bowman's layer, and Descemet's membrane-endothelium complex were similar in the patients with systemic sclerosis and healthy controls (P > 0.05). Total corneal thickness at the apex was 511.1 ± 33.5 µm in the systemic sclerosis group and 528.4 ± 29.5 µm in the control group (P = 0.015). The corneal stroma was thinner in the systemic sclerosis patients compared to the healthy controls (P = 0.02). CONCLUSIONS: The corneal stroma was thinner in the patients with systemic sclerosis compared to that of healthy controls, while the thickness of the anterior sclera was similar in both groups.

The association of pre-photorefractive keratectomy Schirmer-1 test value with postoperative corneal epithelial thickness, ocular surface discomfort, and visual acuity.

PURPOSE: To investigate the association of pre-photorefractive keratectomy Schirmer-1 test value with post-photorefractive keratectomy central corneal epithelial thickness, ocular surface disease index score, and uncorrected distance visual acuity. METHODS: Patients were categorized according to preoperative Schirmer-1 value: the normal Schirmer Group (n=54; Schirmer-1 test value, >10 mm) and the low Schirmer Group (n=52; Schirmer-1 test value, between 6 and 10 mm). We analyzed ablation depth, visual acuity, result of Schirmer-1 test (with anesthesia), tear film break-up time, ocular surface disease index score, central corneal epithelial thickness, and spherical equivalent refraction. RESULTS: We found significant differences between the groups in Schirmer-1 test value, tear film break-up time, and ocular surface disease index score, both preoperatively and postoperatively (p<0.001). The preoperative central corneal epithelial thicknesses of the two groups were similar (p>0.05). After photorefractive keratectomy, the Schirmer-1 test value and spherical equivalent refraction decreased in both groups (p<0.05), and ocular surface disease index scores and central corneal epithelial thickness values increased in the low Schirmer Group (p<0.001) but not in the normal Schirmer Group (p>0.05). The postoperative central corneal epithelial thicknesses of the low Schirmer Group were significantly higher than those of the normal Schirmer Group (p<0.001). Postoperative uncorrected distance visual acuity did not differ significantly between the two groups (p>0.05). CONCLUSIONS: In patients with low Schirmer-1 test values before photorefractive keratectomy, the corneal epithelium thickened and ocular surface complaints increased during the postoperative period. However, changes in the corneal epithelium did not affect the postoperative uncorrected distance visual acuity. To reduce postoperative problems on the ocular surface in these patients, we recommend that dry eye be treated before photorefractive keratectomy.

[New possibilities for reparative therapy of dry eye syndrome]. / Novye vozmozhnosti reparativnoi terapii sindroma «sukhogo glaza¼.

In recent years, among artificial tear preparations that have additional metabolic properties, in addition to moisturizing the ocular surface, there has been a drug Optinol Soft Recovery (LLC JADRAN). In addition to 0.15% sodium hyaluronate, it contains 2% dexpanthenol, which stimulates reparative regeneration of the corneal epithelium, in particular in patients with dry eye syndrome (DES). PURPOSE: This study evaluates the clinical efficacy of the drug Optinol Soft Recovery in the treatment of patients with DES accompanied by xerotic changes in the corneal epithelium. MATERIAL AND METHODS: The study included 82 patients (15 children and 65 adults) with moderate and severe DES accompanied by the following corneal pathology: filamentous keratitis (20 patients, 33 eyes), persistent corneal erosion (28 patients, 49 eyes) and punctate keratopathy (34 patients, 68 eyes). RESULTS: All patients receiving fourfold instillations of the studied drug were observed already during the first 7 days to have increased stability of the tear film and decreased severity of staining of the cornea and conjunctiva with vital dyes (0.1% sodium fluorescein and 3% lissamine green, respectively). Further, as the patients were transferred to an individual instillation regimen, a progressive decrease in the Ocular Surface Disease Index (OSDI), an increase in corneal sensitivity and tear meniscus index were also recorded. The differences in most parameters of the course of xerosis compared to the initial ones were statistically significant starting from day 10-20 of therapy, depending on the initial severity of corneal xerosis (p<0.05-0.001). CONCLUSION: Patients with moderate DES complicated by punctate keratopathy were the most susceptible to therapy with the drug Optinol Soft Recovery, while patients with filamentous keratitis secondary to a severe clinical form of DES were the least susceptible.

Use of nonsteroidal anti-inflammatory drugs in corneal epithelial ingrowth due to traumatic flap dislocation after LASIK: Case report.

RATIONALE: Ophthalmologists mainly treat epithelial ingrowth by lifting the flap and scraping the ingrowth or using scraping combined with phototherapeutic keratectomy, mitomycin C, and so on. The potential usefulness of nonsteroidal anti-inflammatory drugs in such circumstances has not been reported before. PATIENT CONCERNS: A 32-year-old man and a 25-year-old man underwent lifting and scraping of the flap and phototherapeutic keratectomy to remove the epithelial ingrowths. Unfortunately, the ingrowths recurred and continued to develop. DIAGNOSIS: The patients were diagnosed with corneal epithelial ingrowth. INTERVENTIONS: The administration of bromfenac sodium and fluorometholone eye drops. OUTCOMES: Epithelial ingrowths in both patients disappeared after 6 and 1 month of treatment, respectively. There were no adverse reactions to the eye drops. LESSONS: Nonsteroidal anti-inflammatory drugs may be broadly applied in the treatment of epithelial ingrowth after laser in situ keratomileusis.

Severity Classification of Limbal Stem Cell Failure Due to Steven Johnson Syndrome in the Light of the Classification Consensus of Limbal Stem Cell Deficiency.

OBJECTIVES: To examine and to understand the limbal stem-cell deficiency (LSCD) because of Steven-Johnson syndrome (SJS) in line with the new classification system for the first time in the literature. METHODS: Medical records of patients with LSCD because of SJS were reviewed retrospectively. In addition to demographic data and ophthalmologic or systemic findings, anterior segment photographs of the patients were reviewed retrospectively. Limbal stem-cell deficiency severity was graded according to the classification published by the Limbal Stem Cell Working Group. RESULTS: Twenty-four eyes of 14 patients with eye involvement secondary to SJS were included in the study. The mean age of the patients was 36.09±16.70 (9-58) years and the female-to-male ratio was 11:3. The anterior segment photographs of the patients were evaluated by two independent masked observers. Limbal stem-cell deficiency severity was graded according to the classification published by Deng et al. Corneal opacity was divided into three stages according to the area of involvement. Corneal opacity was classified as Stage I if the central 5 mm region of the cornea was not affected, as Stage II if the central 5 mm region of the cornea was affected, and as Stage III if the entire corneal surface was affected. Limbal involvement was classified as Stage A if it was below 50%, as Stage B if it was between 50% and 100%, and as Stage C if it was 100%. CONCLUSION: This is the first study in the literature to describe and classify LSCD because of SJS, according to the new LSCD classification. Consistent with the results, LSCD follows a bimodal distribution. Most patients demonstrated severe (Stage III-32.14%) or mild (Stage IA-21.42%) LSCD.

Regional Variations in Corneal Epithelial Cell Density and Morphology Assessed Using In Vivo Confocal Microscopy.

AIM: To characterize the regional variations in corneal epithelial cell density and morphology using in vivo confocal microscopy (IVCM). METHODS: Corneal imaging (IVCM) at 10 locations was performed; corneal apex (i.e., the center), immediately anterior to the corneal nerve whorl (i.e., slightly inferior to the apex), and four quadrants (superior, nasal, inferior, and temporal) both at 1.5 mm and 4.5 mm from the corneal apex (corresponding to 3 mm central and 9 mm peripheral diameter rings). The data of 21 young adults, aged 18 to 35 years, were analyzed. Cell morphometric parameters, including cell density, area, perimeter, Feret diameter, and circularity, were measured for basal and wing cells using Image J software. RESULTS: There was a significant difference in basal cell density (BCD) ( P <0.001) and wing cell density (WCD) ( P <0.001) for different corneal locations. The BCD (mean±SD: 8,839±416 cells/mm 2 ) and WCD (mean±SD: 5,932±310 cells/mm 2 ) were highest at the corneal nerve whorl compared with all other corneal locations. There were significant differences in wing cell area ( P <0.001), perimeter ( P <0.001), Feret diameter ( P <0.001), and circularity ( P <0.001) at varying corneal locations. CONCLUSION: There are significant regional variations in corneal epithelial cell density and morphology. The BCD and WCD was highest anterior to the corneal nerve whorl.

Modeling dry eye with an air-liquid interface in corneal epithelium-on-a-chip.

Dry eye syndrome (DES) is a complex ocular condition characterized by an unstable tear film and inadequate tear production, leading to tissue damage. Despite its common occurrence, there is currently no comprehensive in vitro model that accurately reproduce the cellular characteristics of DES. Here we modified a corneal epithelium-on-a-chip (CEpOC) model to recapitulate DES by subjecting HCE-T human corneal epithelial cells to an air-liquid (AL) interface stimulus. We then assessed the effects of AL stimulation both in the presence and absence of diclofenac (DCF), non-steroidal anti-inflammatory drug. Transcriptomic analysis revealed distinct gene expression changes in response to AL and AL_DCF, affecting pathways related to development, epithelial structure, inflammation, and extracellular matrix remodeling. Both treatments upregulated PIEZO2, linked to corneal damage signaling, while downregulating OCLN, involved in cell-cell junctions. They increased the expression of inflammatory genes (e.g., IL-6) and reduced mucin production genes (e.g., MUC16), reflecting dry eye characteristics. Metabolomic analysis showed increased secretion of metabolites associated with cell damage and inflammation (e.g., methyl-2-oxovaleric acid, 3-methyl-2-oxobutanoic acid, lauroyl-carnitine) in response to AL and even more with AL_DCF, indicating a shift in cellular metabolism. This study showcases the potential use of AL stimulus within the CEpOC to induce cellular characteristics relevant to DES.

Isolation and characterization of rabbit limbal niche cells.

Limbal niche cells (LNCs) are one of the most important supporting cells for corneal epithelial stem cells (CES), however, research on LNCs has been mostly limited to humans and rats previously. To expand the research work into the rabbit animal model, one of the most often used animals in stem cell study, this study was carried out for the in vitro isolation and identification of rabbit LNCs. Rabbit LNCs were isolated by collagenase A digestion method and single cells were obtained, the cells were then seeded on 5% Matrigel-coated plastic surface and cultured in modified embryonic stem cell medium (MESCM). Three biological replicates of the isolating and characterization were recorded from New Zealand White rabbits aged from 2.5 months to 5 months. LNC markers (VIM/CD90/CD105/SCF/PDGFRß) were analyzed using tyramide signal amplification (TSA) staining, immunohistochemical staining (IHC), western blotting (WB), and real-time reverse transcription polymerase chain reaction (qPCR). TSA staining suggested that VIM was highly expressed in rabbit limbus stroma, which was confirmed by WB, and P63α was expressed in the basal limbus epithelium. Pan-CK and CK12 were highly expressed in the central corneal epithelium but lightly expressed in the limbal epithelium. The WB result indicated that PDGFRß and VIM expressions in rabbit-LNCs P4 were higher than in P1 and P7. In addition, rabbit corneal epithelium highly expressed Paired Box 6 (PAX6) and Epidermal growth factor-like domain 6(EGFL6). For the three repeat experiments, the cell expansion activity of rabbit-LNC was highest at P4. Rabbit-LNCs were passaged from P0 to P7, and the number of cell doublings (NCD) of P4 for the three repeat experiments was 2.816, 2.737, and 2.849. qPCR showed that high mRNA expression levels of VIM, CD90, CD105, SCF, and PDGFRß in rabbit-LNCs P4. In conclusion, rabbit-LNCs could be successfully isolated by the collagenase A digestion method as used in human tissue. There were similar characteristics between rabbit and human LNCs (VIM+/CD90+/CD105+/SCF+/PAX6+/PDGFRß+).

IC3D Classification of Corneal Dystrophies-Edition 3.

PURPOSE: The International Committee for the Classification of Corneal Dystrophies (IC3D) was created in 2005 to develop a new classification system integrating current information on phenotype, histopathology, and genetic analysis. This update is the third edition of the IC3D nomenclature. METHODS: Peer-reviewed publications from 2014 to 2023 were evaluated. The new information was used to update the anatomic classification and each of the 22 standardized templates including the level of evidence for being a corneal dystrophy [from category 1 (most evidence) to category 4 (least evidence)]. RESULTS: Epithelial recurrent erosion dystrophies now include epithelial recurrent erosion dystrophy, category 1 ( COL17A1 mutations, chromosome 10). Signs and symptoms are similar to Franceschetti corneal dystrophy, dystrophia Smolandiensis, and dystrophia Helsinglandica, category 4. Lisch epithelial corneal dystrophy, previously reported as X-linked, has been discovered to be autosomal dominant ( MCOLN1 mutations, chromosome 19). Classic lattice corneal dystrophy (LCD) results from TGFBI R124C mutation. The LCD variant group has over 80 dystrophies with non-R124C TGFBI mutations, amyloid deposition, and often similar phenotypes to classic LCD. We propose a new nomenclature for specific LCD pathogenic variants by appending the mutation using 1-letter amino acid abbreviations to LCD. Pre-Descemet corneal dystrophies include category 1, autosomal dominant, punctiform and polychromatic pre-Descemet corneal dystrophy (PPPCD) ( PRDX3 mutations, chromosome 10). Typically asymptomatic, it can be distinguished phenotypically from pre-Descemet corneal dystrophy, category 4. We include a corneal dystrophy management table. CONCLUSIONS: The IC3D third edition provides a current summary of corneal dystrophy information. The article is available online at https://corneasociety.org/publications/ic3d .

Analysis of the effect of calcium ions on promoting the penetrability of riboflavin into the corneal stroma by iontophoresis.

PURPOSE: To investigate the effect of calcium ions on promoting the penetrability of riboflavin into the corneal stroma by iontophoresis and to analyse the possible mechanism. METHODS: Forty rabbits were divided into five groups randomly: 0.1% riboflavin-balanced salt solution (BSS) by iontophoresis group, 0.1% riboflavin-saline solution by iontophoresis group, 0.1% riboflavin-zinc gluconate solution by iontophoresis group, 0.1% riboflavin-calcium gluconate solution by iontophoresis group and classical riboflavin instillation after corneal de-epithelialization as the control group. The riboflavin concentrations in corneal stroma were determined and compared by high-performance liquid chromatography (HPLC) after removing epithelium and endothelium. RESULTS: Iontophoretic delivery of a 0.1% riboflavin-calcium gluconate solution was the closest to the effect of classical de-epithelialization. The other solvents were unsufficient at enhancing the permeability of the riboflavin. CONCLUSION: Calcium ions can promote the penetrability of riboflavin into the corneal stroma by iontophoresis.

Effect of Topical Programmed Death-Ligand1 on Corneal Epithelium in Dry Eye Mouse.

Dry eye disease (DED) is a growing health concern that impacts millions of individuals every year, and is associated with corneal injury, excessive oxidative stress and inflammation. Current therapeutic strategies, including artificial tears and anti-inflammatory agents, are unable to achieve a permanent clinical cure due to their temporary nature or adverse side effects. Therefore, here, we investigated the effectiveness of the topical administration of programmed death-ligand 1 (PD-L1) in the mouse model of DED. The model was generated in C57BL/6 mice by excising the extra orbital lacrimal gland and causing desiccation stress with scopolamine injections. Subsequently, either phosphate-buffered saline (3 µL/eye) or PD-L1 (0.5 µg/mL) was topically administered for 10 days. Tear volume was evaluated with phenol red thread, and corneal fluorescein staining was observed to quantify the corneal epithelial defect. Corneas were collected for histological analysis, and the expression levels of inflammatory signaling proteins such as CD4, CD3e, IL-17, IL-1ß, pIkB-α, pNF-kB and pERK1/2 were assessed through immunofluorescence and Western blot techniques. Our results demonstrate that desiccating stress-induced corneal epithelial defect and tear secretion were significantly improved by topical PD-L1 and could reduce corneal CD4+ T cell infiltration, inflammation and apoptosis in a DED mouse model by downregulating IL-17 production and ERK1/2-NFkB pathways.

Krupple-like factor 4 (KLF4) methylation signature in host cell in active viral keratitis with epithelial manifestation.

HSV1 presents as epithelial or stromal keratitis or keratouveitis and can lead to sight-threatening complications. KLF4, a critical transcription factor, and regulator of cell growth and differentiation, is essential in corneal epithelium stratification and homeostasis. Here, we want to understand the epigenetic modification specifically the methylation status of KLF4 in epithelium samples of HSV1 keratitis patients. After obtaining consent, epithelial scrapes were collected from 7 patients with clinically diagnosed HSV1 keratitis and 7 control samples (patients undergoing photorefractive keratectomy). Genomic DNA was isolated from the collected samples using the Qiagen DNeasy Kit. Subsequently, bisulfite modification was performed. The bisulphite-modified DNA was then subjected to PCR amplification using specific primers designed to target the KLF4, ACTB gene region, allowing for the amplification of methylated and unmethylated DNA sequences. The amplified DNA products were separated and visualized on a 3% agarose gel. KLF4 hypermethylation was found in 6 out of 7 (85.71%) eyes with viral keratitis, while 1 eye showed hypomethylation compared to PRK samples. Out of these 6, there were 2 each of epithelial dendritic keratitis, epithelial geographical keratitis, and neurotrophic keratitis. The patient with hypomethylated KLF4 had a recurrent case of HSV1 keratitis with multiple dendrites and associated vesicular lesions of the lip along with a history of fever. KLF4 hypermethylation in most viral keratitis cases indicated the under functioning of KLF4 and could indicate a potential association between KLF4 hypermethylation and the development or progression of HSV1 keratitis.

Transmembrane Protein CMTM6 Alleviates Ocular Inflammatory Response and Improves Corneal Epithelial Barrier Function in Experimental Dry Eye.

Purpose: To investigate the impact of transmembrane protein CMTM6 on the pathogenesis of dry eye disease (DED) and elucidate its potential mechanisms. Methods: CMTM6 expression was confirmed by database analysis, real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry. Tear secretion was measured using the phenol red thread test. Immune cell infiltration was assessed through flow cytometry. Barrier function was evaluated by fluorescein sodium staining, immunofluorescence staining of zonula occludens 1 (ZO-1), and electric cell-substrate impedance sensing (ECIS) assessment. For silencing CMTM6 expression, siRNA and shRNA were employed, along with lentiviral vector-mediated overexpression of CMTM6. Proinflammatory cytokine levels were analyzed by RT-PCR and cytometric bead array (CBA) analysis. Results: CMTM6 showed high expression in healthy human and mouse corneal and conjunctival epithelium but was notably reduced in DED. Notably, this downregulation was correlated with disease severity. Cmtm6-/- dry eye (DE) mice displayed reduced tear secretion, severe corneal epithelial defects, decreased conjunctival goblet cell density, and upregulated inflammatory response. Additionally, Cmtm6-/- DE mice and CMTM6 knockdown human corneal epithelial cell-transformed (HCE-T) cells showed more severe barrier disruption and reduced expression of ZO-1. Knockdown of CMTM6 in HCE-T cells increased inflammatory responses induced by hyperosmotic stress, which was significantly mitigated by CMTM6 overexpression. Moreover, the level of phospho-p65 in hyperosmolarity-stimulated HCE-T cells increased after silencing CMTM6. Nuclear factor kappa B (NF-κB) p65 inhibition (JSH-23) reversed the excessive inflammatory responses caused by hyperosmolarity in CMTM6 knockdown HCE-T cells. Conclusions: The reduction in CMTM6 expression on the ocular surface contributes to the pathogenesis of DED. The CMTM6-NF-κB p65 signaling pathway may serve as a promising therapeutic target for DED.

Corneal Epithelial Development and the Role of Induced Pluripotent Stem Cells for Regeneration.

Severe corneal disorders due to infective aetiologies, trauma, chemical injuries, and chronic cicatricial inflammations, are among vision-threatening pathologies leading to permanent corneal scarring. The whole cornea or lamellar corneal transplantation is often used as a last resort to restore vision. However, limited autologous tissue sources and potential adverse post-allotransplantation sequalae urge the need for more robust and strategic alternatives. Contemporary management using cultivated corneal epithelial transplantation has paved the way for utilizing stem cells as a regenerative potential. Humaninduced pluripotent stem cells (hiPSCs) can generate ectodermal progenitors and potentially be used for ocular surface regeneration. This review summarizes the process of corneal morphogenesis and the signaling pathways underlying the development of corneal epithelium, which is key to translating the maturation and differentiation process of hiPSCs in vitro. The current state of knowledge and methodology for driving efficient corneal epithelial cell differentiation from pluripotent stem cells are highlighted.

[Comparison of the Effect of Autologous Serum on Therapy Resistant Corneal Erosions and Ulcers on the Corneal Graft vs. the Patient's Own Cornea]. / Die Wirkung von autologen Serumaugentropfen bei therapieresistenten Erosiones und Ulcera der Kornea bei eigenem im Vergleich zu transplantiertem Gewebe.

PURPOSE: The aim of this study is to compare the healing of corneal epithelial defects or ulcers on the corneal graft in comparison with the patient's own cornea after treatment with 100%, undiluted autologous serum eye drops. METHODS: In a retrospective study over 7 years, we analysed 263 treatments with autologous serum eye drops of persistent corneal epithelial defects (erosions [88%] vs. ulcers [12%]). We compared the epithelial healing tendency of patients with defects on their own cornea (51.9%) vs. patients who had previously undergone penetrating keratoplasty (48.1%). Complete epithelial healing during the 28 days of treatment was considered as therapeutic success. In addition, the recurrence rate of the epithelial defects after finishing the therapy was analysed. RESULTS: 88.2% of the epithelial defects healed during 28 days of therapy. The recurrence rate during follow-up was 5.1%. There was no significant difference with respect to success rate between corneal defects on the patient's own cornea (87.8%) and on the graft (88.6%; p = 0.137). There was a significantly lower success rate for corneal ulcers (74.2%) than for erosions (90.3%; p < 0.001). The recurrence rate of erosions was 4.4%, vs. 4.3% in ulcers during follow-up. CONCLUSION: The results of our study suggest that autologous serum eye drops are a non-invasive and safe alternative treatment for persistent corneal epithelial defects - with no significant difference in patients with a defect on their own cornea vs. defects on the corneal graft. The success rate, but not the recurrence rate, is significantly worse in ulcers than in erosions.