Experimental eye research最新文献

NMDA-mediated excitotoxic retinal injury, altered renin-angiotensin system (RAS) expression and adenosine receptor (AR) signaling are associated with glaucomatous retinal ganglion cells loss. Trans-resveratrol protects against NMDA-induced retinal injury via adenosine receptors. It also alters RAS expressions in relation to cardiovascular functions. However, the mechanistic links among these pathways remain unclear. We hypothesized that the protective effect of trans-resveratrol against NMDA-induced retinal excitotoxicity involves AR mediated regulation of RAS expression. Using a oculonormotensive rat model of NMDA-induced retinal injury, we examined the retinal RAS expression following NMDA exposure with or without trans-resveratrol pre-treatment. To delineate the contribution of AR, effect of trans-resveratrol on retinal RAS expression was studied in the presence of selective adenosine A1 and A2A antagonists. The angiotensinogen, angiotensin II and angiotensin II type 1 receptor expressions were significantly lower in trans-resveratrol pre-treated compared to NMDA-treated group (p < 0.0001). However, the renin expression was significantly greater in trans-resveratrol pre-treated compared to NMDA-treated group (p < 0.05). The alternate RAS proteins including ACE2 and Ang (1-7) showed significantly greater expressions in trans-resveratrol pre-treated compared to NMDA-treated group (p < 0.0001). Overall, trans-resveratrol shifts RAS towards a more active alternate rather than the classical arm. In alignment with these observations, TUNEL staining showed a significantly reduced apoptotic cell count in the ganglion cell layer (GCL) in trans-resveratrol pre-treated compared to NMDA treated group (p < 0.01). Morphological observations showed that it protects against NMDA-induced loss of GCL thickness within inner retina and retinal cell density in GCL (p < 0.01). These effects of trans-resveratrol were abolished by pre-treatment with adenosine A1 but not by A2A receptor antagonist highlighting the role of adenosine-RAS interactions via adenosine A1 receptors in the neuroprotective effect of trans-resveratrol. This study not only clarifies mechanisms underlying the neuroprotective effects of trans-resveratrol but for the first time provides novel insight into adenosine-RAS interactions, which may be explored as potential targets for therapeutic intervention in neurodegenerative conditions.

Developing eye optics, determined by the lens and cornea, must coordinate with the axial length of growing eyes to focus light onto the retina to form an image. It was found that the lens nucleus in zebrafish (Danio rerio)y initially localized anteriorly in the optical axis of larvae, then centralized at older stages. An anteriorly placed lens nucleus is thought to enable a functional optical system in larvae, where eye axial length is short. To determine if a similar mechanism occurs in other aquatic animals, we studied the clawed frog, Xenopus laevis, a fully aquatic species that similarly relies on vision for survival at stages where eyes are initially small. We found that the tadpole lens nucleus was initially located anteriorly in the optical axis. As development proceeded, it moved to a more centralized location by the prometamorphosis period. Similarly, in eyes regenerated after embryonic ablation, tadpole lens nuclei were anteriorly localized and then centralized before metamorphosis, recapitulating the same pattern as control developing eyes. Moreover, the localization of the lens nucleus in the optical axes in both the developing and regenerated Xenopus eyes correlate with axial eye length. Our findings suggest this could be a shared mechanism for eye optical development in at least two aquatic species. Future studies examining how nucleus centralization modulates lens optical power may reveal key mechanisms that coordinate optical development with axial eye growth. These insights could ultimately inform strategies to prevent or delay refractive errors that arise when these processes become mismatched.

The cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway is a key mediator of the innate immune response to cytosolic DNA, with growing implications beyond traditional host defense mechanisms. Recent research has linked the abnormal activation of this pathway to a wide range of ocular diseases, such as age-related macular degeneration, diabetic retinopathy, corneal injuries, glaucoma, and ocular tumors. This review examines the multifaceted roles of cGAS-STING signaling in ocular inflammation, tissue degeneration, fibrosis, angiogenesis, and immune surveillance. We emphasize the mechanistic basis through which the cGAS-STING pathway orchestrates various pathological processes across different ocular compartments, from the ocular surface to the retina. Additionally, we discuss its interactions with autophagy, cellular senescence, and cell death, exploring its potential as a therapeutic target in inflammatory and neoplastic eye conditions. Finally, we identify key unresolved questions and outline future research directions aimed at exploiting cGAS-STING modulation for precision therapies in vision-threatening diseases.

Fundus imaging is an essential technique for detecting anatomical changes indicative of various ophthalmological diseases. These alterations-including changes in the macula, optic disc, fovea, and blood vessels-can signal conditions such as diabetic retinopathy, glaucoma, age-related macular degeneration, cataracts, and myopia. In this paper, we propose a novel hybrid framework for classifying multi-class fundus images by combining deep learning feature extraction with nature-inspired algorithms. Pre-trained ResNet-18 and GoogLeNet architectures are employed to extract features, which are subsequently refined using nature-inspired algorithms including Particle Swarm Optimization, Grey Wolf Optimizer, Differential Evolution, Firefly Algorithm, and Genetic Algorithm. Finally, machine learning classifiers, such as K-Nearest Neighbor, Gaussian Naive Bayes, Support Vector Machine, and Logistic Regression, are applied to the optimized feature sets. Our extensive experiments on the ODIR and RFMiD datasets demonstrate that the proposed framework-specifically the combination of the Firefly Algorithm with K-Nearest Neighbor (FAKNN)-achieves state-of-the-art performance, reaching 100% accuracy, recall, precision, Kappa, F1 score, and Area Under the Curve. This approach not only improves diagnostic accuracy but also demonstrates significant potential for clinical application, facilitating early intervention and better patient outcomes.

Oxidative stress plays a critical role in lens fibrosis, and nuclear factor erthroid 2-related factor 2 (Nrf2) is a key antioxidant transcription factor. This study investigates the specific role and underlying mechanism of Nrf2 in fibrotic cataract using in vitro and in vivo models. An in vitro model of fibrotic cataract was established by treating lens epithelial cells (LECs) with TGF-β2 (10 ng/mL). We found that oxidative stress participated in epithelial-mesenchymal transition (EMT) in LECs, concomitant with reduced Nrf2 expression. Moreover, Nrf2 overexpression alleviated oxidative stress, suppressed cell migration, and inhibited EMT. The anterior capsule injury method was utilized to establish a murine model of anterior subcapsular cataract (ASC). In the ASC model, LECs displayed increased oxidative stress and reduced Nrf2 expression. Consistently, Nfe2l2-knockout mice exhibited exacerbated lens fibrosis and higher oxidative stress levels compared to wild-type controls. The mechanism of Nrf2 in lens fibrosis was then investigated by RNA sequencing and validated in LECs in vitro. Our data revealed that Nrf2 promoted PINK1-mediated mitophagy, through which it attenuated oxidative stress and suppressed EMT in LECs. To elucidate how Nrf2 regulates PINK1, the Nrf2 binding sites in the promoter region of PINK1 were predicted using the JASPAR database and subsequently confirmed by both chromatin immunoprecipitation and electrophoretic mobility shift assay. We found that Nrf2 directly binds to the PINK1 promoter to drive its transcription. Collectively, our study suggests that Nrf2 activation mitigates lens fibrosis by promoting PINK1-dependent mitophagy, identifying the Nrf2-PINK1 axis as a potential therapeutic target.

The purpose of this study was to investigate the relationship between amino acid mutations in the quinolone resistance-determining region (QRDR) of Staphylococcus epidermidis and its susceptibility to fluoroquinolones, as well as the potential of single nucleotide polymorphism (SNP) genotyping for rapid detection of resistant strains. Thirty-three S. epidermidis strains were analyzed (25 from preoperative patients, 8 from keratoconjunctivitis patients). Minimum inhibitory concentrations (MICs) of fluoroquinolones were determined using the broth microdilution method. The QRDR sequences of resistance-related genes (gyrA, gyrB, parC, parE) were analyzed by direct sequencing. SNP genotyping was performed using TaqMan probes targeting conserved regions and mutation sites. The correlation between fluoroquinolone use and mutation counts was analyzed using the Mann-Whitney U test and Spearman's rank correlation test. Fifteen strains showed resistance to fluoroquinolones. Mutations in gyrA, parC, and/or parE were detected in 15 fluoroquinolone-resistant strains. Double mutations in both gyrA and parC were associated with the strongest resistance. Among the 18 non-resistant strains, 17 had no mutations, while one strain had a mutation in parE (Asn404Ser). No mutations were found in gyrB. A significant difference in mutation presence was observed between fluoroquinolone-use and non-use groups (p = 0.026). Additionally, a positive correlation was found between fluoroquinolone use duration and mutation counts (p = 0.025). SNP genotyping was accurate for all strains and successfully identified mutations in gyrA, parC, and parE. The duration of fluoroquinolone use influences mutation counts in the QRDR sequences. Additionally, SNP genotyping is a rapid and effective method for identifying fluoroquinolone-resistant S. epidermidis strains.

Glutathione (GSH) and cysteine (Cys) are crucial low-molecular-weight thiol antioxidants that protect ocular tissues from oxidative stress, a key driver of age-related eye diseases. The balance between their reduced (GSH/Cys) and oxidized (GSSG/CySS) forms reflect tissue oxidative status. Despite their importance, existing analytical methods typically quantify these analytes separately, requiring multiple assays. In this work, a robust liquid chromatography-tandem mass spectrometry method for the concurrent quantification of GSH, GSSG, Cys, and CySS in ocular tissues has been developed and validated. The workflow uses derivatization of reduced thiols with monobromobimane, followed by solid-phase extraction and separation using reversed-phase high-performance liquid chromatography with an 8-min gradient elution of acetonitrile and heptafluorobutyric acid. Analytes were detected by positive-ion mode multiple reaction monitoring on a triple quadrupole mass spectrometer and quantified using extracted ion chromatograms. The method demonstrated excellent linearity, precision, and accuracy, with all quality control samples meeting acceptance criteria. Method sensitivity and reproducibility were also validated. Application to human, rat, bovine, and rabbit lenses, as well as rat retina, cornea, aqueous humor, and vitreous humor revealed distinct tissue- and species-specific redox profiles. Rat ocular tissues were found to be in a predominantly reduced state, with reduced thiols at higher concentrations than their oxidized counterparts. Rabbit lenses exhibited the highest GSH concentrations, while human lenses showed lower levels, a finding potentially related to donor age. This method has broad applicability in studies investigating the role of oxidative stress in ocular health and the development of novel treatments to prevent ocular disease.

Meibomian gland dysfunction (MGD) is the leading cause of evaporative dry eye disease and arises from failure of a coordinated molecular network that normally maintains meibomian gland homeostasis. In health, endocrine-lipidogenic signaling via peroxisome proliferator-activated receptor-γ (PPARγ) and androgen receptor (AR), trophic pathways such as epidermal growth factor and Hedgehog, a circadian-metabolic axis coupling nicotinamide adenine dinucleotide (NAD⁺)-dependent steroidogenesis to lipid output, and neuroimmune circuits involving Toll-like receptors and nuclear factor-κB (NF-κB) act together to regulate stem/progenitor maintenance, meibocyte differentiation and lipid secretion. In MGD these axes become progressively uncoupled: hormonal and metabolic stress reduce NAD⁺ and intracrine androgen production, dampening AR-PPARγ activity; loss of trophic support exhausts basal progenitor pools; and chronic NF-κB-driven inflammation with Th17 and interleukin-33 (IL-33) signaling promotes ductal hyperkeratinization, acinar loss and fibrosis. Lipidomic studies show a shift from cholesteryl esters (CEs) toward free fatty acids, along with remodeling of O-acyl-ω-hydroxy fatty acid (OAHFA) profiles, oxidized lipids and eicosanoids, which stiffen meibum, destabilize the tear film lipid layer and fuel inflammation. Recent single-cell and organoid studies further map cellular heterogeneity and disease-linked lineage changes. Biomarkers such as cholesteryl ester/wax ester ratios, OAHFA profiles, eicosanoids, cytokines and imaging metrics offer read-outs of axis-specific dysfunction. Therapeutically, emerging strategies seek to correct these defects by enhancing AR-PPARγ signaling and NAD⁺-dependent steroidogenesis, re-engaging trophic pathways, normalizing ductal keratinization with "soft" keratolytics and inhibiting inflammatory circuits. This review integrates these mechanisms, disease networks, biomarker signatures and interventions into a unified model to support mechanism-based, biomarker guided precision care in MGD.