PURPOSE:To determine how the biomechanical properties of the retina vary across different quadrants of the eye and how commonly used storage media affect retinal biomechanics. METHODS:A total of 130 retinal strips were dissected from 90 six-month-old pigs eyes for uniaxial tensile testing. Vertical and horizontal strips were extracted from each quadrant, with ten samples per group. Four different storage media-Ringer's solution, balanced salt solution (BSS), phosphate-buffered saline (PBS), and vitreous-were used. Strip thickness was measured using calibrated optical microscopy. Tensile testing was conducted at an extension rate of 9 mm/min. RESULTS:Ringer's solution significantly affected the mechanical properties of the retina, making the samples stiffer (25.5 ± 5.6 kPa) and stronger (12.8 ± 1.5 kPa) than the control (2.6 ± 1.3 kPa; 1.8 ± 0.7 kPa). A significant difference (p < 0.05) in tensile strength and tangent modulus was found between the blood vessel group (2.6 ± 0.5 KPa, 5.2 ± 1.6 KPa) and the temporal-horizontal group without blood vessels (1.4 ± 0.4 KPa, 3 ± 1.1 KPa). The inferior-horizontal group showed a significantly higher tensile strength than the inferior-vertical group (p = 0.019). CONCLUSION:Blood vessels significantly impact retinal biomechanics. The retina also showed anisotropic behaviour with tensile properties varying by strip orientation within the same location. The storage media used can significantly affect biomechanical properties. TRANSLATIONAL RELEVANCE:Biomechanical properties of the retina significantly impact the outcome of subretinal injections and other surgical procedures. Understanding how these properties vary across the retina could optimise strategies for subretinal bleb generation.
BACKGROUND:Retinal hypoxia contributes to photoreceptor death in multiple blinding diseases. Astragalus polysaccharide (APS) exhibits broad bioactivity, but its protection against hypoxic photoreceptor injury remains unclear. OBJECTIVE:This study evaluated the cytoprotective effect and mechanism of APS in hypoxic 661W photoreceptor cells, focusing on oxidative stress, mitochondrial function, apoptosis, and autophagy. METHODS:661W cells were cultured under normoxia (21% O2) or hypoxia (2% O2) with or without APS (100-2000 μg/mL). Cell viability, cytotoxicity, reactive oxygen species (ROS) levels, and mitochondrial membrane potential (ΔΨm) were assessed by Cell Counting Kit-8 (CCK-8), lactate dehydrogenase (LDH), DCFH-DA, and JC-1 assays. Apoptosis was detected by TUNEL staining. HIF-1α, Bcl-2, Bax, cleaved caspase-3, AIF, and LC3 were analyzed by Western blotting. RESULTS:Under normoxia, APS ≤1000 μg/mL was non-cytotoxic, whereas 2000 μg/mL induced toxicity. Under hypoxia, APS significantly attenuated hypoxia-induced cell death in a concentration-dependent manner, with optimal protection observed at 1000 μg/mL, and the protective effect was more pronounced at 24-48 h than at 72 h. Mechanistically, APS reduced intracellular ROS levels, preserved ΔΨm, attenuated hypoxia-induced HIF-1α accumulation, inhibited both caspase-dependent and AIF-mediated apoptotic pathways, and enhanced autophagy. CONCLUSION:APS protects photoreceptors against acute hypoxic injury through a multi-target mechanism modulating oxidative stress, mitochondrial stabilization, dual apoptosis inhibition, and autophagy activation, with a concentration-dependent safety profile. However, its benefit is limited under prolonged hypoxia, suggesting its potential applicability in acute retinal hypoxic conditions.
BACKGROUND:Diabetic corneal epitheliopathy is a significant ocular complication of diabetes whose pathogenic mechanisms remain incompletely understood. This study aimed to elucidate the cellular and molecular mechanisms underlying diabetic corneal epitheliopathy and to identify potential therapeutic targets using single-cell RNA sequencing (scRNA-seq). METHODS:Corneal epithelial tissues were processed into single cells and clustered based on marker gene expression. Integrated bioinformatic analyses were performed, including pseudotime trajectory, cell cycle, gene set enrichment, hdWGCNA, and cell communication analyses. This approach identified BHLHE40 and its interacting partner THBS1 as key candidate genes. Their functional significance was confirmed through knockdown experiments in high glucose-induced human corneal epithelial cells, supporting their potential role in diabetic corneal epitheliopathy pathogenesis. RESULTS:We analyzed 40,976 single cells from human corneal epithelium, classifying them into seven distinct clusters. The most pronounced differences were observed in the basal cells of the limbal stem cell niche between diabetic and control groups. Diabetic epithelia exhibited upregulation of genes associated with glycolysis, circadian rhythm, and hypoxia, alongside downregulation of genes involved in corneal differentiation and oxidative phosphorylation. Knockdown of BHLHE40 reversed high glucose-induced oxidative stress and concurrently reduced THBS1 expression, while knockdown of THBS1 itself lowered the expression of inflammatory factors. Direct binding between BHLHE40 and THBS1 was confirmed by CUT&Tag-qPCR analysis. CONCLUSION:Our findings demonstrate that BHLHE40 and THBS1 are implicated in the pathogenesis of diabetic corneal epitheliopathy, highlighting a promising novel target for therapeutic intervention.
Circadian entraining input to the suprachiasmatic nucleus (SCN) is primarily from intrinsically photosensitive retinal ganglion cells (ipRGCs). While several retinal and optic nerve diseases are associated with ipRGC dysfunction, the role of ipRGC dysfunction in the context of SCN-mediated circadian disruption remains incompletely understood. We performed a systematic review of human studies examining relationships between ipRGC dysfunction and circadian effects. Databases were searched from inception until Apr 2026. Studies were independently assessed for risk of bias, screened, and data extracted by two reviewers. Due to high methodological variability, results were summarised qualitatively. GRADE was used to assess the certainty of evidence. 3,632 records were identified, of which 10 studies were included, 8 focused on ipRGC functional measures, and 2 on ipRGC structural measures. Across the 8 functional-measures studies, ipRGC dysfunction and impairment in one or more SCN-mediated circadian outcomes were consistently observed, and this association was independently corroborated in 6 of the 8 studies. Advanced glaucoma and diabetic retinopathy showed the greatest evidence of circadian disruption, including decreased melatonin excretion, delayed or altered dim-light melatonin onset, and failure to suppress melatonin with light exposure. Both ipRGC function and circadian regulation were preserved in mitochondrial optic neuropathies. Two additional studies showed strong links between post-illumination pupil response (PIPR) and melatonin-related circadian measures. In two post-mortem ipRGC structural measure studies, ipRGC density was reduced by 76.9% in severe diabetic retinopathy compared with controls, and age-related ipRGC dendritic atrophy was observed. Evidence in humans suggests a directionally consistent but very low-certainty relationship between SCN circadian disruption and ipRGC dysfunction, but the pattern and severity of disruption differ across disease states. PIPR has the potential to serve as a non-invasive marker of circadian disruption. The overall certainty of evidence is still very low, however, and requires larger, long-term studies with standardized circadian phenotyping.
PURPOSE:To describe the novel clinical phenotypes and develop a three-dimensional (3D) primary myofibroblast culture model to investigate morphological alterations associated with CPAMD8 deficiency. METHODS:We identified novel CPAMD8 variants by exome sequencing. Primary myofibroblasts from human ciliary muscle were cultured in a Matrigel-based 3D system, and CPAMD8 was knocked down by siRNA to assess effects on aggregate growth, morphology, and gene expression. RESULTS:Two novel nonsense variants of the CPAMD8 gene were identified within the pedigree. We identified megalocornea, lentis ectopia, and iris hypoplasia in patients with ASGD8, whereas glaucoma was not observed. Notable alterations in corneal biometry were observed in patients with ASGD8 for the first time. Additionally, as a preliminary observation based on the two affected individuals, reduced retinal vascular density was noted. Upon knockdown of CPAMD8 expression, three-dimensional cultured myofibroblasts demonstrated restricted proliferation, as observed under a microscope and confirmed by CCK-8 assay. Furthermore, ACTA2 expression was downregulated, and the expression of certain TGF-β receptors (TGFBR2 and TGFBR3) was altered, while TGFBR1 and SMAD2 remained unchanged, suggesting a partial rather than global disruption of TGF-β signaling. These findings are consistent with structural abnormalities of the anterior segment in ASGD8. CONCLUSIONS:ASGD8 can cause abnormalities in both the anterior and posterior eye segments. Our newly developed three-dimensional myofibroblast model offers a straightforward, efficient, and cost-effective approach for investigating genetic eye disorders.
PURPOSE:Corneal crosslinking (CXL) using riboflavin and ultraviolet A (UV-A) illumination is widely used to stabilize progressive ectatic corneal disorders such as keratoconus. However, the photochemical reaction generates oxidative stress and may induce apoptosis, while potential differences between healthy human corneal fibroblasts (HCF) and human corneal fibroblasts derived from keratoconus corneas (KC-HCF) remain insufficiently understood. This study examined in-vitro changes in pro- and anti-apoptotic markers in HCF and KC-HCF following riboflavin-UV-A illumination. METHODS:Cell cultures of HCFs (n = 5) and KC-HCFs (n = 5) were incubated with 0.01% or 0.1% riboflavin-dextran solutions (RF) for subsequent crosslinking and either placed in a dark chamber or illuminated with UV-A light (250 s, 375 nm, 2 J/cm2). The expression profiles of pro-apoptotic markers (BCL-2 homologous antagonist/killer (BAK), BCL-2 associated agonist of cell death protein (BAD), caspase-9 (CASP9) and cytochrome c (CYCS)) and the anti-apoptotic marker Baculoviral IAP Repeat Containing 5 (BIRC5) were analyzed using quantitative reverse transcription polymerase chain reaction (RT-PCR) (0.01%/0.1% RF; n = 5; for 2 h (h), 4 h, n = 3; for 24 h) and Western blot (0.1% RF; n = 4 for 24 h). Cell proliferation was assessed after 2 h, and ultrastructural changes were examined by transmission electron microscopy (TEM) after 24 h (0.1% RF; n = 1). RESULTS:Cell proliferation was significantly reduced in HCFs and KC-HCFs after 2 h in both treatment groups (0.01%/0.1% RF). Gene expression analysis showed a significant increase in BAK and BAD expression in KC-HCFs after 24 h with 0.01% RF, but not after 0.1% riboflavin-UV-A illumination. For CYCS and CASP9 gene expression levels remained unchanged for HCFs and KC-HCFs in both treatment groups. BIRC5 was significantly reduced in HCFs (0.01%/0.1% RF) and in KC-HCFs (0.1% RF). Protein expression analysis revealed a significant increase in BAK and CYCS after 24 h in HCFs and KC-HCFs, while CASP9 expression was significantly decreased. TEM showed some ultrastructural features of apoptosis after 24 h (0.1% RF). CONCLUSION:Riboflavin-UV-A illumination induced a time- and dose-dependent cellular response in both HCFs and KC-HCFs with KC-HCFs showing an increased sensitivity to photochemical stress.
Mitochondrial DNA (mtDNA) damage is strongly implicated in age-related macular degeneration (AMD), the most frequent cause of age-mediated visual impairment in developed countries. Here, we investigated and compared the fate of acutely induced oxidation damage in primary retinal pigment epithelial (RPE) cells. The individual RPE clones responded heterogeneously to hydrogen peroxide, both with respect to cell sensitivity and mtDNA damage formation. Peroxide-induced mtDNA damage in human RPE (hRPE) was fully repaired within 4 h. In parallel, hRPE cells secreted mtDNA from both apical and basolateral surfaces (AP-mtDNA and BL-mtDNA, respectively) independent of peroxide exposure and that could not be explained by detached cells. Most mtDNA was released apically, and the quality of AP-mtDNA was comparable to that of intracellular mtDNA (c-mtDNA). In contrast, BL-mtDNA constituted only 3% of AP-mtDNA, and exhibited a 10-fold higher damage burden. The difference in mtDNA quality suggests a non-random selection of mtDNA molecules to be targeted for export in apical versus basolateral direction. To investigate this, we analyzed epigenetic marks (m.545 methylation) and SNPs (heteroplasmies) in extracellular and cellular mtDNA. Extracellular mtDNA in general appeared to be more modified than c-mtDNA and that AP-mtDNA differs from BL-mtDNA, which is indicative of a targeted secretion. Porcine RPEs (pRPEs) from a minipig model of Huntington's Disease associated with impaired epithelial polarity (TgHD) displayed approximately 2-fold higher leakage of AP-mtDNA than control pRPEs, but lower than hRPEs. Together, our data imply that extracellular mtDNA originating from RPE shapes the outer retina and the implications for polar secretion are discussed.
Peters Anomaly (PA) is the leading cause for corneal transplants in pediatric patients. We investigated whether disruption of Eph-ephrin signaling leads to phenotypes associated with PA, including microphthalmia, cloudy cornea, coloboma, cataract, corneo-lenticular touch (CLT), irido-corneal adhesion (ICA), and persistent fetal vasculature (PFV). Freshly enucleated mouse eyes were imaged under a dissection microscope, and high-resolution confocal images were collected to compare mouse eyes with genetic disruption of EphA2 or ephrin-A5. In ephrin-A5 knockout (KO or -/-) eyes, we commonly found microphthalmia, cloudy cornea, coloboma, CLT, ICA, anterior subcapsular cataracts, and PFV; control and EphA2-/- eyes did not display these phenotypes with significant frequency. Defects in ephrin-A5-/- eyes were often unilateral, and bilateral defects were not always the same between contralateral eyes. We did not observe premature eye opening in ephrin-A5-/- mice, and eye defects were present in ephrin-A5-/- pups at birth, suggesting embryonic development abnormalities. Imaging of tissues from live ephrin-A5-/- eyes revealed abnormal corneal epithelial cells in deeper corneal layers, shallow anterior chamber, and anterior lens defects due to CLT. Immunostaining demonstrated nerve patterning and epithelial cell defects in ephrin-A5-/- corneas. This work reveals that Eph-ephrin signaling is needed for separation of the embryonic lens from the cornea during development and nerve patterning in the cornea. Although ephrin-A5 has not been directly linked to PA, this KO model can be utilized for detailed studies of the cellular defects for all clinical signs of PA and suggests that Eph-ephrin signaling is involved in PA.
The accumulation of ferrous ions and resulting oxidative stress within the retinal pigment epithelium triggers ferroptosis, leading to photoreceptor degeneration in dry age-related macular degeneration (dAMD), which is a disease currently without effective therapy. As ferroptosis has been identified as a molecular target of epigallocatechin-3-gallate (EGCG) in other diseases, this study aimed to investigate the protective role of EGCG and its mechanism against ferroptosis in NaIO3-induced ARPE-19 cell and RPE injury. We observed that iron overload disrupts iron homeostasis in both cellular and animal models, leading to RPE damage via ferroptosis activation. In ARPE-19 cells, EGCG attenuated NaIO3-induced injury by reducing Fe2+, MDA, and LDH levels, increasing GSH content, and upregulating SLC7A11 and GPX4 expression, effects which were equivalent to those produced by Fer-1. Mechanistically, EGCG exerted its anti-ferroptotic effect by binding strongly to NF-κB p65 and inhibiting its activation, consistent with the effects of the NF-κB inhibitor QNZ and NF-κB p65 silencing. In a dAMD model, EGCG administration suppressed ferroptosis, downregulated NF-κB p65 expression, and ameliorated RPE damage. In conclusion, these findings suggest that EGCG alleviates RPE damage associated with NF-κB p65-mediated ferroptosis, providing new insights into AMD pathogenesis and a promising therapeutic strategy.
This study characterized fibrosis-associated pigment changes in neovascular age-related macular degeneration (nAMD) using fluorescence lifetime imaging microscopy (FLIM). Retinal cross sections from human donor eyes with nAMD (n = 5; mean age 91.0 ± 2.8 years) and control eyes without maculopathy (n = 5; 83.0 ± 1.9 years) were analyzed at λexc 488 nm and λexc 780 nm. In total, 116 regions of interest (50 μm width each) were assessed across the fovea, parafovea, and areas of subretinal fibrosis in nAMD eyes and compared with corresponding locations in controls. Fluorescence lifetimes (FLTs) were evaluated using a linear mixed-effects model across pigment in unremarkable retinal pigment epithelium (RPE), pigment in RPE above fibrosis, pigment within fibrosis, and pigment in the choroid. At λexc 488 nm, FLTs were significantly prolonged in RPE above fibrosis (0.54 ± 0.04 ns) compared with unremarkable RPE (0.49 ± 0.04 ns, linear mixed-effect model: p = 0.04). Pigment within fibrosis (0.51 ± 0.03 ns) showed similar lifetimes to unremarkable RPE (p = 0.58), while choroidal pigment exhibited markedly shorter lifetimes (0.23 ± 0.04 ns; p < 0.001). At λexc 780 nm, pigment within fibrosis displayed shorter lifetimes (0.27 ± 0.03 ns) than unremarkable RPE (0.34 ± 0.04 ns, p = 0.04), and choroidal pigment again showed the shortest values (0.11 ± 0.01 ns; p < 0.001). Dual-wavelength FLIM reveals distinct lifetime patterns at fibrotic locations consistent with an RPE origin of fibrosis-associated pigment in nAMD.
Age-related macular degeneration (AMD) is the most common blinding disease in the western world and is currently incurable. Although the exact causes of AMD are not clear, the primary origin of pathology appears to be the aged retinal pigment epithelium (RPE) exhibiting signs of lysosomal dysfunction and oxidative damage. RPE is responsible for the daily digestion of photoreceptor outer segments (POS), imposing a heavy continuous burden on the lysosomal network. A cellular model of RPE lysosomal dysfunction can be achieved by feeding RPE with a single pulse of POS, leading to the accumulation of autofluorescence granules (AFG), similar to lipofuscin in vivo. Here we show that synchronous phagocytosis of POS leads to early transient mTOR activation followed by inhibition in late phagosome maturation. One of its substrates, the transcription factor EB (TFEB) increases during phagosome maturation albeit mostly in its inactive phosphorylated form. We questioned whether modulation of the mTOR/TFEB axis could improve POS clearance and hence reduce AFG load. Treatment of POS-fed cells after the appearance of AFGs with rapamycin, an mTORC1 inhibitor results in ∼30% reduction of AFG load. This effect is dependent on active lysosomal enzymes and induction of active dephosphorylated TFEB with consequent activation of GADD34 and lysosomal biogenesis. As a proof of concept, we show that overexpressing a constitutively active form of unphosphorylated TFEB dramatically reduces POS-dependent AFG accumulation. Overall, this study suggests that viral or pharmacological approaches activating the TFEB pathway in the RPE could be beneficial as cell-protective treatment of early/intermediate cases of AMD, acting to delay progression of the disease.
This study was conducted to determine how Aquaporin 0 (AQP0) CatTohm natural mutation, which causes congenital cataracts and smaller eyes (microphthalmia) in mice, affects eye development, lens clarity, physiology, and mechanics. Eyes of wild-type (WT) and CatTohm heterozygous (Cat+/Tohm) mutant mice were examined; Cat+/Tohm showed significantly smaller eyes, indicating microphthalmia. Lenses from wild-type (WT), AQP0 heterozygous (AQP0+/-), and Cat+/Tohm mutant mice were imaged, and transparency was quantified. In Cat+/Tohm, transparency was greatly reduced compared with that of WT and AQP0+/- (P < 0.0001). Cell-to-cell adhesion studies using a cell aggregation assay on L-cells transfected with either WT or CatTohm AQP0 showed a significant decrease in cell aggregation in CatTohm AQP0 compared with WT-expressing cells (P < 0.0001). Lens stiffness was determined using compression stress testing, which revealed Cat+/Tohm lenses substantially less stiff than WT lenses (P < 0.001). Gap Junction Coupling (GJC) and Hydrostatic Pressure (HP) were assessed to evaluate the physiological effects on lens microcirculation and homeostasis; Cat+/Tohm lenses displayed significantly increased GJC (P < 0.0001) and reduced HP (P < 0.0001) relative to those in WT lenses. In summary, the results indicate that the mutation has altered cell-to-cell adhesion, biomechanics, GJC, and HP; together, these changes lead to the development of dominant cataracts and microphthalmia. AQP0 serves as a multifunctional protein in the lens, modulating transparency, fiber cell-to-fiber cell adhesion, GJC, HP, biomechanics, microcirculation, and homeostasis.
It has been proposed that in the absence of a blood supply and any direct innervation, the lens utilizes a variety of mechanosensitive ion channels to transduce changes to its internal and external environments into the activation of signaling pathways that alter fiber cell structure and hence overall lens function. One such mechanosensitive channel is Piezo1, the activation of which has been shown to phosphorylate Myosin light chain kinase (MLCK) and increase the expression of Transglutaminase 2 in fiber cells. To complement these functional studies, we have conducted a comprehensive mapping of the distribution of Piezo1 and Piezo2, the other member of this protein family, throughout all regions of the mouse lens. Using Western blotting, we first show that in addition to Piezo1, the mouse lens also expresses Piezo2. Using immunohistochemistry, we then show that both proteins are present throughout all regions of the lens, but are more concentrated in a discrete zone of high intensity labelling in mature fiber cells in the inner cortical region of the adult mouse lens. Despite being localized to the same localized ring the two proteins exhibited distinctly different subcellular distributions. In the outer cortex Piezo1 was more localized to the membrane, while Piezo2 was predominantly located in the cytoplasm of differentiating fiber cells. To determine at what stage of development this prominent ring of Piezo1/2 labelling was formed, immunohistochemistry was performed at different stages of embryonic and postnatal development. We found Piezo1 and Piezo2 to be both first expressed in the lens vesicle at E10, with both proteins exhibiting a constant level of cytoplasmic labelling across the whole lens throughout embryonic development and up to P6. This pattern of localization changed from cytoplasmic to membranous at around P15 when the tunica vasculosa lentis was almost fully regressed and eye opening occurred. Our findings suggest that Piezo1/2 recruitment to the plasma membrane is developmentally regulated and associated with a key transitional stage of lens fiber cell maturation.
Meibomian gland dysfunction (MGD) is the leading cause of evaporative dry eye disease. The multifactorial pathogenesis of MGD remains poorly understood, with limited understanding of the interplay between the microbiome and meibum lipid composition. This study investigates the ocular microbiota and lipid profiles in patients with MGD (n = 20, diagnosed according to TFOS DEWS III criteria) and in Healthy Controls (HC, n = 24). Bacterial isolates from the tear film wash, cultured on blood agar, were assessed for their ability to form biofilms. Meibum collected from the upper and lower eyelids of the same patients was profiled for lipidomics (LC-MS/MS). Bacteria were identified through 16S rRNA gene sequencing and BLAST search analysis. MGD samples showed an increased abundance of Gram-negative bacteria and a significant reduction in the Genus Bacillus. Biofilm-forming capacity was markedly higher in MGD isolates. MGD meibum revealed increased levels of phospholipids and cholesteryl esters. Lipid pathway enrichment analysis (LIPEA) of the differentially abundant lipids linked them to glycerophospholipid metabolism, ferroptosis, autophagy, inflammation, and apoptosis. Spearman correlation analysis between MGD and HC revealed positive correlations between the abundance of biofilm formers and the percentage of polar lipids, total bacterial counts and reduced lipid layer thickness, suggesting their potential interactions in MGD. The results of the study indicate that MGD is characterized by an altered ocular surface microbial composition, increased biofilm-forming capability, and disrupted lipid composition.
Pathological corneal neovascularization remains a major therapeutic challenge due to the limited efficacy and safety of currently available antiangiogenic treatments. Although C-type lectins from snake venom possess various biological activities, their potential to modulate pathological ocular angiogenesis has not been explored. This study investigated the antiangiogenic effects of Leuculectin, a C-type lectin isolated from Bothrops leucurus venom using an experimental model of corneal neovascularization (CNV), a HUVEC (human umbilical vein endothelial cell) tube formation assay, and the chick embryo chorioallantoic membrane (CAM) assay. In the HUVEC tube formation assay, Leuculectin demonstrated strong antiangiogenic activity. In the CAM assay, Leuculectin applied at concentrations of 1.5, 2.5 and 3.5 μg/mL significantly decreased new vessel formation, with effects comparable to those achieved with 250 μg/mL bevacizumab, a widely used clinical antiangiogenic agent. In the HET-CAM assay Leuculectin was classified as non-irritant and supporting its potential safety for topical ocular use. In the suture-induced CNV model, topical Leuculectin resulted in a significant reduction in neovascularized areas, achieving results similar to bevacizumab administered at considerably higher doses. These findings indicate that Leuculectin has potent antiangiogenic properties and significant therapeutic promise for ocular angiogenic disorders. Histological analyses and optical coherence tomography (OCT) further revealed improved organization of corneal epithelial and stromal layers, accompanied by fewer blood vessels in treated regions. Overall, the results suggest that Leuculectin may serve as a safe and effective alternative for managing ocular angiogenic diseases. Further studies are required to elucidate its mechanisms of action and assess its potential clinical applications.
PURPOSE:This study aimed to evaluate the prophylactic potential of fingolimod, an FDA-approved sphingosine-1-phosphate receptor modulator, in preventing proliferative vitreoretinopathy (PVR) in an experimental rat model induced by intravitreal platelet-rich plasma (PRP) injection. METHODS:Thirty-two male Wistar albino rats were randomly assigned to four groups (n = 8 per group): Control, Fingolimod, PVR, and PVR + Fingolimod. PVR was induced by intravitreal injection of autologous PRP in the PVR and PVR + Fingolimod groups. Fingolimod (0.3 mg/kg/day) was administered by oral gavage for 21 days to the rats in the Fingolimod and PVR + Fingolimod groups. Histopathological evaluation included grading of retinal folds, epiretinal membrane (ERM) scoring, staging of retinal detachment and assessments of overall PVR severity, vessel count, retinal thickness, vitreoretinal traction membrane presence, and retinal-layer disruption. Body weight was monitored at baseline and at euthanasia. A complete blood count was also performed. RESULTS:Prophylactic fingolimod administration significantly reduced the indicators of PVR severity. The PVR + Fingolimod group showed significantly lower retinal fold grades (1.12 ± 0.99 vs. 3.25 ± 1.04, p < 0.001), ERM grades (1.25 ± 0.46 vs. 3.12 ± 0.99, p < 0.001), and retinal detachment grades (1.38 ± 0.52 vs. 2.75 ± 0.71, p < 0.001) than the PVR group. Neovascularization was significantly lower in the PVR + Fingolimod group (6.50 ± 1.31 vs. 10.50 ± 3.96 vessels, p < 0.001). Vitreoretinal traction membrane was present in 75% of eyes showing PVR but completely absent in the PVR + Fingolimod group (p < 0.05). Prophylactic fingolimod administration also significantly reduced white blood cell (3.75 ± 1.52 vs. 8.70 ± 2.39 × 103/μL, p < 0.001) and lymphocyte (1.90 ± 0.90 vs. 6.86 ± 1.91 × 103/μL, p < 0.001) counts. Post-hoc power analysis indicated statistical power > 0.80 for most primary endpoints. Body weight monitoring showed no overt systemic toxicity or weight loss. CONCLUSIONS:To the best of our knowledge, this proof-of-concept study provides the first preclinical evidence that prophylactic fingolimod administration effectively prevents PVR development, consistent with anti-inflammatory and immunomodulatory mechanisms. Thus, Fingolimod represents a promising prophylactic candidate for PVR prevention, warranting further clinical investigation.
Diabetic retinopathy (DR) has traditionally been viewed as a consequence of cumulative oxidative damage. However, the clinical phenomenon of metabolic memory, whereby prior hyperglycemia continues to exert adverse effects despite subsequent glucose normalization, indicates a more complex redox biology. This review advances a paradigm shift from considering reactive species merely as markers of injury to interpreting oxidative signatures as a dynamic, compartment-specific code that records glycemic history, predicts disease trajectory, and enables therapeutic subtyping. We synthesize evidence across multiple redox layers, including protein oxidative post-translational modifications such as S-glutathionylation and tyrosine nitration, lipid peroxidation products, mitochondrial DNA damage, and epigenetic rewriting mediated by SET domain-containing lysine methyltransferase 7 (SETD7, also known as SET7/9)-dependent monomethylation of histone H3 lysine 4 (H3K4me1). Persistent failure of mitochondrial quality control and maladaptive chromatin remodeling may stabilize hyperglycemia-induced redox programs after glucose normalization, whereas exosomal signaling may contribute to their intercellular propagation. In this context, metabolic memory refers to the durable yet potentially modifiable maintenance of these molecular programs rather than absolute biological irreversibility. Moving beyond the failure of generic antioxidant approaches, we introduce a clinical taxonomy of redox subphenotypes, glutathione-deficient, lipid-peroxidation-dominant, mitochondrial reactive oxygen species (ROS)-driven, and epigenetic redox-lock, each linked to candidate, predominantly preclinical, mechanism-matched interventions, including thiol-repleting agents, ferroptosis inhibitors, mitophagy-enhancing or mitochondrial-protective agents, and epigenetic modulators. Finally, we outline an integrated roadmap combining single-cell redox profiling, liquid-biopsy multi-omics, and biomarker-enriched clinical trial designs to translate redox signatures into precision management. Decoding the redox code may extend the traditional oxidative stress paradigm by revealing biologically heterogeneous molecular states with distinct therapeutic implications.
