OBJECTIVE: To investigate the therapeutic effects of hydrogel dressings on neurotrophic keratitis in rats.
METHODS: Male Wistar rats, aged 42-56d, were randomly divided into control, experimental, and treatment groups, each consisting of five rats. The experimental and treatment groups underwent neurotrophic keratitis modeling in both eyes. After successful modeling, biomedical hydrogels formed with polyvinyl alcohol and polyvinyl pyrrolidone were used in treatment group for 7d. Ocular irritation response and keratitis index scores, Schirmer\'s test, tear film break-up time (BUT), sodium fluorescein staining, and hematoxylin and eosin (HE) staining were used to evaluate the effectiveness of the treatment.
RESULTS: The neurotrophic keratitis model was successfully established in rats with severe ophthalmic nerve injury, characterized by keratitis, ocular irritation, reduced tear secretion measured by decreased BUT and Schirmer test values, corneal epithelial loss, and disorganized collagen fibers in the stromal layer. Following treatment with hydrogel dressings, significant improvements were observed in keratitis scores and ocular irritation symptoms in model eyes. Although the recovery of tear secretion, as measured by the Schirmer\'s test, did not show statistical differences, BUT was significantly prolonged. Fluorescein staining confirmed a reduction in the extent of corneal epithelial loss after treatment. HE staining revealed the restoration of the structural disorder in both the epithelial and stromal layers to a certain extent.
CONCLUSIONS: Hydrogel dressing reduces ocular surface irritation, improves tear film stability, and promotes the repair and restoration of damaged epithelial cells by maintaining a moist and clean environment on the ocular surface in the rat model.

Dry eye disease (DED) is caused by inflammation and damage to the corneal surface due to tear film instability and hyperosmolarity. Various eye drops are used to treat this condition. Each eye drop has different properties and mechanisms of action, so the appropriate drug should be used according to clinical phenotypes. This study aims to compare the therapeutic mechanisms of cyclosporine A (CsA) and diquafosol tetrasodium (DQS). An experimental in vivo/in vitro model of DED using hyperosmolarity showed decreased cell viability, inhibited wound healing, and corneal damage compared to controls. Treatment with cyclosporine or diquafosol restored cell viability and wound healing and reduced corneal damage by hyperosmolarity. The expression of the inflammation-related genes il-1β, il-1α, and il-6 was reduced by cyclosporine and diquafosol, and the expression of Tnf-α, c1q, and il-17a was reduced by cyclosporine. Increased apoptosis in the DED model was confirmed by increased Bax and decreased Bcl-2 and Bcl-xl expression, but treatment with cyclosporine or diquafosol resulted in decreased apoptosis. Diquafosol increased NGF expression and translocation into the extracellular space. DED has different damage patterns depending on the progression of the lesion. Thus, depending on the type of lesion, eye drops should be selected according to the therapeutic target, focusing on repairing cellular damage when cellular repair is needed or reducing inflammation when inflammation is high and cellular damage is severe.

Given that the corneal epithelium is situated on the outermost part of the eye, its functions can be influenced by external temperatures and chemical substances. This study aimed to elucidate the expression profile of chemosensory receptors in corneal epithelial cells and analyze their role in eye function regulation. A comprehensive analysis of 425 chemosensory receptors in human corneal epithelial cells-transformed (HCE-T) revealed the functional expression of TRPV4. The activation of TRPV4 in HCE-T cells significantly increased the expression of membrane-associated mucins MUC1, MUC4, and MUC16, which are crucial for stabilizing tear films, with efficacy comparable to the active components of dry eye medications. The present study suggests that TRPV4, which is activated by body temperature, regulates mucin expression and proposes it as a novel target for dry eye treatment.

Dry eye is a prevalent ophthalmic disease. Ocular surface inflammation in the hyperosmolar environment of the tear film is critical in dry eye progression. Quercetin has strong anti-inflammatory effects; however, its exact mechanism of action in dry eye is not fully understood. Therefore, this study investigated whether quercetin could inhibit the damage sustained to human corneal epithelial cells (HCECs) in a hyperosmolar environment through its anti-inflammatory effects. HCECs were cultured in a complete medium and were divided into four groups: normal, model, quercetin, and inhibitor. The proliferation of HCECs was detected by Ki67 staining; the expression levels of PTEN, p-PI3K and p-AKT were detected by Western blotting and immunofluorescence staining; the relative mRNA expression levels of PTEN, PI3K, AKT, IL-6 and TNF-ɑ were detected by quantitative real-time PCR; the relative expression levels of IL-6 and TNF-α were detected by enzyme-linked immunosorbent assay. In this study, the proliferation of HCECs in the model group was found to be significantly inhibited compared with that in the normal group; however, quercetin was effective in improving the proliferation of HCECs, decreasing the relative expression of p-PI3K, p-AKT, IL-6, TNF-ɑ as well as increasing PTEN. In conclusion, this study demonstrated that quercetin could promote the proliferation of HCECs and reduce the expression of inflammatory factors by inhibiting the PTEN/PI3K/AKT pathway in the hyperosmolarity-induced HCECs model.

Soluble factors in the secretome of Acanthamoeba castellanii play crucial roles in the pathogenesis of Acanthamoeba keratitis (AK). Investigating the pathological effects of A. castellanii-derived conditioned medium (ACCM) on ocular cells can provide insights into the damage inflicted during AK. This study examined ACCM-induced cytotoxicity in primary human corneal stromal cells (CSCs) and a human SV40 immortalized corneal epithelial cell line (ihCECs) at varying ACCM concentrations (25 %, 50 %, 75 %, and 100 %). MTT, AlamarBlue, Sulforhodamine B, lactate dehydrogenase, and Caspase-3/7 activation assays were used to assess the impact of ACCM on the cell viability, proliferation and apoptosis. Additionally, fluorescent staining was used to reveal actin cytoskeleton changes. ACCM exposure significantly decreased cell viability, increased apoptosis, and disrupted the actin cytoskeleton, particularly at higher concentrations and longer exposures. Proteases were found to mediate these cytopathogenic effects, highlighting the need for characterization of A. castellanii proteases as key virulence factors in AK pathogenesis.

UNASSIGNED: Dry eye syndrome is a common ocular disease that causes morbidity, high healthcare burden, and decreased quality of life. In this study, we evaluated the beneficial effects of a standardized extract of small black soybean (EYESOY®) in a benzalkonium chloride (BAC)-induced murine model of dry eye.
UNASSIGNED: Experimental dry eye was induced by instillation of 0.02% BAC on the right eye of the Sprague-Dawley rats. Saline solution or EYESOY were administered orally every day for 8 weeks.
UNASSIGNED: EYESOY significantly improved tear volume in the cornea compared with that in the BAC group. Moreover, EYESOY inhibited damage to the corneal epithelial cells and lacrimal glands by suppressing the oxidative and inflammatory responses in a mouse dry eye model. It also increased the goblet cell density and mucin integrity in the conjunctiva.
UNASSIGNED: Our results suggest that EYESOY has the potential to alleviate dry eye syndrome.

Severe corneal injury can lead to blindness even after prompt treatment. 14-3-3zeta, a member of an adaptor protein family, contributes to tissue repair by enhancing cellular viability and inhibiting fibrosis and inflammation in renal disease or arthritis. However, its role in corneal regeneration is less studied. In this study, filter disc of 2-mm diameter soaked in sodium hydroxide with a concentration of 0.5 N was placed at the center of the cornea for 30 s to establish a mouse model of corneal alkali injury. We found that 14-3-3zeta, which is mainly expressed in the epithelial layer, was upregulated following injury. Overexpression of 14-3-3zeta in ocular tissues via adeno-associated virus-mediated subconjunctival delivery promoted corneal wound healing, showing improved corneal structure and transparency. In vitro studies on human corneal epithelial cells showed that 14-3-3zeta was critical for cell proliferation and migration. mRNA-sequencing in conjunction with KEGG analysis and validation experiments revealed that 14-3-3zeta regulated the mRNA levels of ITGB1, PIK3R1, FGF5, PRKAA1 and the phosphorylation level of Akt, suggesting the involvement of the PI3K-Akt pathway in 14-3-3zeta-mediated tissue repair. 14-3-3zeta is a potential novel therapeutic candidate for treating severe corneal injury.

Ocular exposure to particulate matter (PM) causes local inflammation; however, the influence of neutrophils on PM-induced ocular inflammation is still not fully understood. In this study, we constructed a system to investigate the role of PM in ocular inflammation using a co-culture of human corneal epithelial cells (HCE-T) and differentiation-induced neutrophils (dHL-60). To investigate whether HCE-T directly endocytosed PM, we performed a holographic analysis, which showed the endocytosis of PM in HCE-T. The cytokines and chemokines produced by HCE-T were measured using an ELISA. HCE-T treated with PM produced IL-6 and IL-8, which were inhibited by N-Acetyl-L-cysteine (NAC), suggesting the involvement of ROS. Their co-culture with dHL-60 enhanced their production of IL-6, IL-8, and MCP-1. This suggests an inflammatory loop involving intraocular corneal epithelial cells and neutrophils. These cytokines and chemokines are mainly regulated by NF-κB. Therefore, this co-culture system was examined in the presence of an IKK inhibitor known to downregulate NF-κB activity. The IKK inhibitor dramatically suppressed the production of these factors in co-culture supernatants. The results suggest that the inflammatory loop observed in the co-culture is mediated through ROS and the transcription factor NF-κB. Thus, the co-culture system is considered a valuable tool for analyzing complex inflammations.

The repair mechanism for corneal epithelial cell injuries encompasses migration, proliferation, and differentiation of corneal epithelial cells, and extracellular matrix remodeling of the stromal structural integrity. Furthermore, it involves the consequential impact of corneal limbal stem cells (LSCs). In recent years, as our comprehension of the mediating mechanisms underlying corneal epithelial injury repair has advanced, it has become increasingly apparent that growth factors play a pivotal role in this intricate process. These growth factors actively contribute to the restoration of corneal epithelial injuries by orchestrating responses and facilitating specific interactions at targeted sites. This article systematically summarizes the role of growth factors in corneal epithelial cell injury repair by searching relevant literature in recent years, and explores the limitations of current literature search, providing a certain scientific basis for subsequent basic research and clinical applications.

Patients with advanced chronic kidney disease (CKD) have elevated circulating calcium × phosphate product levels and exhibit soft tissue calcification. Besides the cardiovascular system, calcification is commonly observed in the cornea in CKD patients on hemodialysis. Cardiovascular calcification is a cell-mediated, highly regulated process, and we hypothesized that a similar regulatory mechanism is implicated in corneal calcification with the involvement of corneal epithelial cells (CECs). We established a mouse model of CKD-associated corneal calcification by inducing CKD in DBA/2J mice with an adenine and high phosphate diet. CKD was associated with aorta and corneal calcification as detected by OsteoSense staining and corneal Ca measurement (1.67-fold elevation, p < 0.001). In vitro, excess phosphate and Ca induced human CEC calcification in a dose-dependent and synergistic manner, without any influence on cell viability. High phosphate and Ca-containing osteogenic medium (OM; 2.5 mmol/L excess phosphate and 0.6 mmol/L excess Ca over control) increased the protein expression of Runx2 and induced its nuclear translocation. OM increased the expression of the bone-specific Ca-binding protein osteocalcin (130-fold increase, p < 0.001). Silencing of Runx2 attenuated OM-induced CEC calcification. Immunohistology revealed upregulation of Runx2 and overlapping between the Runx2 and the Alizarin red positive areas of calcification in the cornea of CKD mice. This work sheds light on the mechanism of CKD-induced corneal calcification and provides tools to test calcification inhibitors for the prevention of this detrimental process.