Rat Cornea Research Articles

Oxidative Stress Suppresses Cellular Autophagy in Corneal Epithelium.

Oxidative stress is a major pathogenesis of certain ocular surface diseases. This study investigated the association of oxidative stress and cellular autophagy in corneal epithelium. We applied hydrogen peroxide (H2O2) to induce oxidative damage to cultured human corneal epithelial (HCE) cells and rat corneas. Cell viability, Western blotting of caspase 8, and TUNEL staining were conducted to measure the cellular injury. The production of reactive oxygen species (ROS) was measured and the levels of the following marker and key factors of ROS were also measured to detect oxidative stress: 3-nitrotyrosine, nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), superoxide dismutase, catalase, and glutathione S-transferase P. The following key factors of autophagy were measured: LC3, beclin 1, Atg 12, and P62. We also applied an agonist of autophagy, rapamycin, in the experiment. Cellular injury and oxidant damage were induced after exposure to H2O2 in HCE cells and rat corneas, such as increases of cell death and production of ROS; upregulation of a ROS generation enzyme, NOX4; and downregulation of degradation factors of ROS, superoxide dismutase, catalase, and glutathione S-transferase P. However, the process of cellular autophagy was suppressed by the measurements of LC3, beclin 1, Atg 12, and P62. Furthermore, application of rapamycin antagonized the cellular and oxidant injury induced by H2O2 but increased the level of autophagy in HCE cells. The oxidative stress of corneal epithelium is associated with the inhibition of cellular autophagy.

Evaluation of voriconazole anti-Acanthamoeba polyphaga in vitro activity, rat cornea penetration and efficacy against experimental rat Acanthamoeba keratitis.

Acanthamoeba keratitis (AK) is a sight-threatening infectious disease. Its effective and safe medical therapy remains highly debated. Recently, voriconazole, a monotriazole with noted in vitro activity against a large variety of fungi, has been successfully used both topically and systemically to treat human AK cases. To measure anti-Acanthamoeba polyphaga in vitro activity, anti-rat AK efficiency and rat cornea penetration of eye-drop and oral voriconazole. A. polyphaga was maintained in axenic cultures. In vitro, amoebicidal and cysticidal activities of voriconazole were measured using an XTT assay. AK lesions of Sprague Dawley rats were scored from grade 0 to grade 3. For 21 days, from day 7 post-infection, voriconazole (1% solution) eye drops were instilled or voriconazole was administered by gavage (60 mg/kg/day). After killing, superficial corneal epithelium scrapings were cultured and analysed by PCR, and eye-globe histology was performed. Cornea and plasma concentrations were determined using 2D HPLC separation and tandem MS. In vitro, voriconazole inhibited trophozoite proliferation with an IC50 value of 0.02 mg/L and an IC90 value of 2.86 mg/L; no cysticidal effect was found. In AK rats, eye drops reduced clinical worsening from day 7 to day 14 post-infection and oral voriconazole was not effective. Voriconazole cornea concentrations were directly dependent on the frequency of eye-drop instillations, which resulted in lower plasma concentrations, whilst oral voriconazole resulted in lower cornea concentrations. Present data underline the need for high-frequency eye-drop instillation regimens for efficient AK therapy.

Hypoxia modulates the development of a corneal stromal matrix model

Deposition of matrix proteins during development and repair is critical to the transparency of the cornea. While many cells respond to a hypoxic state that can occur in a tumor, the cornea is exposed to hypoxia during development prior to eyelid opening and during the diurnal sleep cycle where oxygen levels can drop from 21% to 8%. In this study, we used 2 three-dimensional (3-D) models to examine how stromal cells respond to periods of acute hypoxic states. The first model, a stromal construct model, is a 3-D stroma-like construct that consists of human corneal fibroblasts (HCFs) stimulated by a stable form of ascorbate for 1, 2, and 4 weeks to self-assemble their own extracellular matrix. The second model, a corneal organ culture model, is a corneal wound-healing model, which consists of wounded adult rat corneas that were removed and placed in culture to heal. Both models were exposed to either normoxic or hypoxic conditions for varying time periods, and the expression and/or localization of matrix proteins was assessed. No significant changes were detected in Type V collagen, which is associated with Type I collagen fibrils; however, significant changes were detected in the expression of both the small leucine-rich repeating proteoglycans and the larger heparan sulfate proteoglycan, perlecan. Also, hypoxia decreased both the number of Cuprolinic blue-positive glycosaminoglycan chains along collagen fibrils and Sulfatase 1, which modulates the effect of heparan sulfate by removing the 6-O-sulfate groups. In the stromal construct model, alterations were seen in fibronectin, similar to those that occur in development and after injury. These changes in fibronectin after injury were accompanied by changes in proteoglycans. Together these findings indicate that acute hypoxic changes alter the physiology of the cornea, and these models will allow us to manipulate the conditions in the extracellular environment in order to study corneal development and trauma.

Time-dependent LXR/RXR pathway modulation characterizes capillary remodeling in inflammatory corneal neovascularization

Inflammation in the normally immune-privileged cornea can initiate a pathologic angiogenic response causing vision-threatening corneal neovascularization. Inflammatory pathways, however, are numerous, complex and are activated in a time-dependent manner. Effective resolution of inflammation and associated angiogenesis in the cornea requires knowledge of these pathways and their time dependence, which has, to date, remained largely unexplored. Here, using a model of endogenous resolution of inflammation-induced corneal angiogenesis, we investigate the time dependence of inflammatory genes in effecting capillary regression and the return of corneal transparency. Endogenous capillary regression was characterized by a progressive thinning and remodeling of angiogenic capillaries and inflammatory cell retreat in vivo in the rat cornea. By whole-genome longitudinal microarray analysis, early suppression of VEGF ligand-receptor signaling and inflammatory pathways preceded an unexpected later-phase preferential activation of LXR/RXR, PPARα/RXRα and STAT3 canonical pathways, with a concurrent attenuation of LPS/IL-1 inhibition of RXR function and Wnt/β-catenin signaling pathways. Potent downstream inflammatory cytokines such as Cxcl5, IL-1β, IL-6 and Ccl2 were concomitantly downregulated during the remodeling phase. Upstream regulators of the inflammatory pathways included Socs3, Sparc and ApoE. A complex and coordinated time-dependent interplay between pro- and anti-inflammatory signaling pathways highlights a potential anti-inflammatory role of LXR/RXR, PPARα/RXRα and STAT3 signaling pathways in resolving inflammatory corneal angiogenesis.

The Expression of Calcium Sensing Receptor in Normal and Diabetic Rat Eyes.

BackgroundCalcium sensing receptor (CaSR) is widely expressed in many tissues of the body, but it is rarely reported to be expressed in the eyes. This research explored the expression and distribution of CaSR in eye tissues of normal and diabetic rats.Material/MethodsThirty male Sprague Dawley (SD) rats were randomly divided into a diabetic and a normal group. Diabetes mellitus (DM) models were successfully established by intraperitoneal injection of streptozotocin. The expression and distribution of CaSR in the rat eyeballs were detected by immunohistochemistry. Quantitative RT-PCR and western blotting were used to detect the presence of CaSR in normal and diabetic rats.ResultsCaSR was detected in the cornea, lens epithelium, and retina. CaSR was expressed the most in the cornea, followed by the lens epithelium, and the retina (p<0.05). The expression of CaSR was decreased in the eye tissue of diabetic rats (p<0.05).ConclusionsIn this study, CaSR was detected in rat cornea, lens, and retina. It was significantly decreased in the eyes of diabetic rats. This indicated that the downregulated expression of CaSR was associated with diabetic oculopathy.

Reduction in Histone H3 Acetylation and Chromatin Remodeling in Corneas of Alloxan-Induced Diabetic Rats.

To evaluate acetylation of histone H3, chromatin remodeling, nuclear size and shape, DNA ploidy, and distribution of nucleolus organizing regions (NORs) in corneal epithelial and stromal cells of diabetic and nondiabetic rats. Diabetes was induced by a single intraperitoneal injection of alloxan. All diabetic rats (n = 20) included in the study had 4 weeks of moderate-to-severe hyperglycemia (plasma glucose levels >400 mg/dL). Acetylated histone H3 levels were quantified in corneal tissue using a colorimetric assay. Chromatin remodeling, nuclear sizes (area/perimeter) and shapes (circularity), and DNA ploidies were evaluated from Feulgen-stained tissue sections using video image analysis. Distributions of NORs were studied in tissue sections impregnated with silver ions. Ophthalmic clinical parameters, including corneal sensitivity, were investigated. Twenty nondiabetic rats were used as controls. Acetylation of histone H3 was reduced in the corneas of the diabetic rats. Nuclei in corneal epithelial cells of diabetic rats compacted chromatin, increased in size, modified their shapes, and elevated DNA ploidy. The only nuclear change observed in the corneal stromal cells of diabetic rats was chromatin decompaction. The size of the silver-stained NOR did not differ between the study samples. The corneal sensitivity in diabetic rats was 51.8% lower than that in nondiabetic rats. The results of this study show that alloxan-induced diabetes altered the histone H3 acetylation pattern and compromised the chromatin supraorganization in corneal tissue/cells. Continued research is needed to understand the clinical and morphofunctional significance of changes in corneal cell nuclei of diabetic individuals.

Selective IKK2 inhibitor IMD0354 disrupts NF-\u03baB signaling to suppress corneal inflammation and angiogenesis

Corneal neovascularization is a sight-threatening condition caused by angiogenesis in the normally avascular cornea. Neovascularization of the cornea is often associated with an inflammatory response, thus targeting VEGF-A alone yields only a limited efficacy. The NF-κB signaling pathway plays important roles in inflammation and angiogenesis. Here, we study consequences of the inhibition of NF-κB activation through selective blockade of the IKK complex IκB kinase β (IKK2) using the compound IMD0354, focusing on the effects of inflammation and pathological angiogenesis in the cornea. In vitro, IMD0354 treatment diminished HUVEC migration and tube formation without an increase in cell death and arrested rat aortic ring sprouting. In HUVEC, the IMD0354 treatment caused a dose-dependent reduction in VEGF-A expression, suppressed TNFα-stimulated expression of chemokines CCL2 and CXCL5, and diminished actin filament fibers and cell filopodia formation. In developing zebrafish embryos, IMD0354 treatment reduced expression of Vegf-a and disrupted retinal angiogenesis. In inflammation-induced angiogenesis in the rat cornea, systemic selective IKK2 inhibition decreased inflammatory cell invasion, suppressed CCL2, CXCL5, Cxcr2, and TNF-α expression and exhibited anti-angiogenic effects such as reduced limbal vessel dilation, reduced VEGF-A expression and reduced angiogenic sprouting, without noticeable toxic effect. In summary, targeting NF-κB by selective IKK2 inhibition dampened the inflammatory and angiogenic responses in vivo by modulating the endothelial cell expression profile and motility, thus indicating an important role of NF-κB signaling in the development of pathologic corneal neovascularization.

An Anti-VEGF-B Antibody Fragment Induces Regression of Pre-Existing Blood Vessels in the Rat Cornea.

We tested the ability of an antibody fragment with specificity for vascular endothelial growth factor-B (VEGF-B) to regress nascent and established corneal blood vessels in the rat. A single chain variable antibody fragment (scFv) with specificity for VEGF-B was engineered from the 2H10 hybridoma. Binding to rat, mouse, and human VEGF-B was confirmed by surface plasmon resonance. Activity of the anti-VEGF-B scFv on developing and established corneal blood vessels was assessed following unilateral superficial cautery in male and female outbred Sprague Dawley rats. Groups (untreated, control scFv-treated, or anti-VEGF-B scFv-treated) comprised 6 to 22 rats. Treatment consisted of 5 μL scFv, 1 mg/mL, applied topically five times per day for 14 days, or two subconjunctival injections, 50 μg scFv each, applied 7 days apart, or combined topical and subconjunctival treatment. Corneal vessel area was quantified on hematoxylin-stained corneal flat-mounts, and groups were compared using the Mann-Whitney U test, with post hoc Bonferroni correction. Immunohistochemistry for cleaved caspase-3 was performed. Topical anti-VEGF-B scFv therapy alone did not regress corneal blood vessels significantly (P > 0.05). Subconjunctival injection and combined treatment regressed 14-day established corneal blood vessels (25% reduction in vessel area [P = 0.04] and 37% reduction in vessel area [P < 0.001], respectively, compared to results in untreated controls). Cleaved caspase-3 was identified in vascular endothelial cells of anti-VEGF-B scFv-treated corneas. In scFv-treated rats, corneal endothelial cell function was maintained to 12 weeks after treatment and a normal blink reflex was present. The anti-VEGF-B scFv significantly regressed established but not developing corneal blood vessels in rats.

Effect of lentivirus-mediated gene silencing, targeting toll-like receptor 2, on corneal allograft transplantation in rats

AimThe present work aims to assess the effectiveness of lentiviral vector (LV) mediated Toll-like receptor 2 (TLR2) gene silencing in the survival of transplanted corneal allografts, against immune rejection, in rats. MethodsLV mediated TLR2 small interference RNA (SiRNA) with enhanced green fluorescent protein (eGFP) [LV-TLR2-siRNA-eGFP] was realised and transfected to both rat corneal epithelial (EC) and stromal cells (SC). Multiplicity of infection (MOI) was optimized for transfection efficiency using flow cytometric (FCM) analysis. Viability of transfected cells and the success rate of TLR2 gene silencing were respectively determined by CCK-8 assay and western blot assay. The in-vivo experiments were subjected to a penetrating keratoplasty (PK) performed between host Sprague Dawley (SD) and donor Wistar/SD rats, randomly dividing them into 4 groups including the allograft, isograft, allograft treated with LV-eGFP (LV blank control) and allograft treated with LV-TLR2-siRNA-eGFP (LV treated group). The rejection index (RI) was then recorded under a slit lamp, every day following surgery. Expression of the TLR2 and Myeloid differentiation primary response gene 88 (MyD88) were detected by using immunohistochemistry on day 9 post-surgery, whereas grafts’s TLR2 and MyD88 mRNA were determined on day 5, 9, and 14 post-surgery performing RT-PCR and, normal rat corneas were included as additional controls. ResultsTransfected cells showed the strongest eGFP expression when MOI was 200 with an efficiency of 77.5% for EC and 76.3% for SC. CCK-8 assay, as measured at 72 and 96h post transfection, showed no significant changes in the cell viability (both EC and SC) between the transfected and the control group (p>0.05, p>0.05). Western blot results demonstrated a successful down regulation of TLR2 expression by LV-TLR2-SiRNA-eGFP, in both EC and SC. In vivo, compared to allograft group, LV treated group demonstrated less edema, opacity and neovascularization. Immunohistochemical analysis revealed a lower expression of TLR2 and MyD88 in isograft and LV treated group as compared to allograft group. TLR2 and MyD88 mRNA were detected in all grafts, and increased over time. With its highest expression in allograft group (peak on day 9), the mRNA expression for TLR2 and MyD88 showed a significant difference amongst the groups, on both day 9 and 14 (p<0.001). ConclusionsLV mediated TLR2 siRNA could effectively down regulate the TLR2 expression via RNA interference and prolong the survival of corneal grafts, although not necessarily able to prevent the rejection.

Visualizing Micro-anatomical Structures of the Posterior Cornea with Micro-optical Coherence Tomography

Diagnosis of corneal disease and challenges in corneal transplantation require comprehensive understanding of corneal anatomy, particularly that of the posterior cornea. Micro-optical coherence tomography (µOCT) is a potentially suitable tool to meet this need, owing to its ultrahigh isotropic spatial resolution, high image acquisition rate and depth priority scanning mode. In this study, we explored the ability of µOCT to visualize micro-anatomical structures of the posterior cornea ex vivo and in vivo using small and large animals. µOCT clearly delineated cornea layers and revealed micro-anatomical structures, including not only polygonal endothelial cells, stellate keratocytes, collagen fibres and corneal nerve fibres but also new structures such as the dome-shaped basolateral side of endothelial cells and lattice structures at the interface between endothelium and Descemet’s membrane. Based on these observations, a short post-harvest longitudinal study was conducted on rat cornea to test the feasibility of using µOCT to monitor the quality of endothelial cells. This study successfully reveals a series of morphological features and pathological changes in the posterior cornea at the cellular level in situ and in real time with µOCT. These findings enrich knowledge of corneal anatomy and suggest that µOCT may be a promising imaging tool in corneal transplantation.

Contrast enhancement of spectral domain optical coherence tomography using spectrum correction

We report a spectrum correction method to enhance the image contrast of spectral domain optical coherence tomography (SD-OCT). Our method treats SD-OCT signals as the product of harmonic signals backscattered from a sample comprising a series of discrete reflectors and a window corresponding to the light source spectrum. The method restores the magnitude of the main lobe of the axial point spread function (PSF) by estimating the magnitudes of the backscattered harmonic signals and strengthens OCT signals using these estimated values. Experimental results acquired from fresh rat corneas and fixed human aortic atherosclerosis tissues show that our method provides clearer microstructural information than the conventional methods by improving the contrast to noise ratios (CNRs) by 1.4779 dB and 3.2595 dB, respectively. This improved image quality is obtained without any hardware change, making our method a cost-effective alternative to compete with hardware advances.

Genome-wide expression datasets of anti-VEGF and dexamethasone treatment of angiogenesis in the rat cornea

Therapeutics against pathologic new blood vessel growth, particularly those targeting vascular endothelial growth factor (VEGF) are of enormous clinical interest. In the eye, where anti-VEGF agents are in widespread clinical use for treating retinal and corneal blindness, only partial or transient efficacy and resistance to anti-VEGF agents are among the major drawbacks. Conversely, corticosteroids have long been used in ophthalmology for their potency in suppressing inflammation and angiogenesis, but their broad biological activity can give rise to side effects such as glaucoma and cataract. To aid in the search for more targeted and effective anti-angiogenic therapies in the eye, we present here a dataset comparing gene expression changes in dexamethasone versus anti-Vegfa treatment of inflammation leading to angiogenesis in the rat cornea. Global gene expression analysis with GeneChip Rat 230 2.0 microarrays was conducted and the metadata submitted to Expression Omnibus repository. Here, we present a high-quality validated dataset enabling genome-wide comparison of genes differentially targeted by dexamethasone and anti-Vegf treatments, to identify potential alternative therapeutic targets for evaluation.

Genome-wide expression differences in anti-Vegf and dexamethasone treatment of inflammatory angiogenesis in the rat cornea

Angiogenesis as a pathological process in the eye can lead to blindness. In the cornea, suppression of angiogenesis by anti-VEGF treatment is only partially effective while steroids, although effective in treating inflammation and angiogenesis, have broad activity leading to undesirable side effects. In this study, genome-wide expression was investigated in a suture-induced corneal neovascularization model in rats, to investigate factors differentially targeted by dexamethasone and anti-Vegf. Topical treatment with either rat-specific anti-Vegf, dexamethasone, or normal goat IgG (sham) was given to sutured corneas for 48 hours, after which in vivo imaging, tissue processing for RNA microarray, and immunofluorescence were performed. Dexamethasone suppressed limbal vasodilation (P < 0.01) and genes in PI3K-Akt, focal adhesion, and chemokine signaling pathways more effectively than anti-Vegf. The most differentially expressed genes were confirmed by immunofluorescence, qRTPCR and Western blot. Strong suppression of Reg3g and the inflammatory chemokines Ccl2 and Cxcl5 and activation of classical complement pathway factors C1r, C1s, C2, and C3 occurred with dexamethasone treatment, effects absent with anti-Vegf treatment. The genome-wide results obtained in this study provide numerous potential targets for specific blockade of inflammation and angiogenesis in the cornea not addressed by anti-Vegf treatment, as possible alternatives to broad-acting immunosuppressive therapy.

High-intensity corneal collagen crosslinking with riboflavin and UVA in rat cornea.

Corneal collagen cross-linking (CXL) halts human corneal ectasias progression by increasing stromal mechanical stiffness. Although some reports describe that this procedure is effective in dealing with some infectious and immunologic corneal thinning diseases, there is a need for more animal models whose corneal thickness more closely resemble those occurring in these patients. To meet this need, we describe here high-intensity protocols that are safe and effective for obtaining CXL in rat corneas. Initially, a range of potentially effective UVA doses were evaluated based on their effectiveness in increasing tissue enzymatic resistance to dissolution. At UVA doses higher than a threshold level of 0.54 J/cm2, resistance to enzymatic digestion increased relative to that in non-irradiated corneas. Based on the theoretical threshold CXL dose, a CXL regimen was established in which the UVA tissue irradiance was 9 mW/cm2, which was delivered at doses of either 2.16, 2.7 or 3.24 J/cm2. Their dose dependent effects were evaluated on ocular surface morphological integrity, keratocyte apoptotic frequency, tissue thickness and endothelial cell layer density. Doses of 2.16 and 2.7 J/cm2 transiently decreased normal corneal transparency and increased thickness. These effects were fully reversed after 14 days. In contrast, 3.24 J/cm2 had more irreversible side effects. Three days after treatment, apoptotic frequency in the CXL-2.16 group was lower than that at higher doses. Endothelial cell losses remained evident only in the CXL-3.24 group at 42 days posttreatment. Stromal fiber thickening was evident in all the CXL-treated groups. We determined both the threshold UVA dose using the high-intensity CXL procedure and identified an effective dose range that provides optimal CXL with minimal transient side effects in the rat cornea. These results may help to provide insight into how to improve the CXL outcome in patients afflicted with a severe corneal thinning disease.

Comprehensive Modeling of Corneal Alkali Injury in the Rat Eye

ABSTRACTPurpose: To characterize the molecular, clinical, and histopathological profiles in the rat cornea after alkali injury over a 21-day period.Methods: Alkali injury was induced in one eye of male Lewis rats. Corneal opacity and corneal neovascularization were assessed daily. Real-time qRT-PCR analysis and immunohistochemical staining were conducted to examine inflammation, neovascularization, and fibrosis.Results: We found that within 2 hours of chemical exposure, corneal opacification rapidly developed with an acute increase in various cytokine expressions, while several cytokines demonstrated a secondary peak by day 7. Early neutrophil infiltration peaked at day 1 post-injury while macrophage infiltration peaked at day 7. Throughout the time course of the study, corneal opacity persisted and neovascularization, lymphangiogenesis, and fibrosis progressed.Conclusions: This study highlights the molecular, clinical, and histopathological changes throughout the progression of alkali injury in the rat cornea. These profiles will assist in the development of new strategies and therapies for ocular alkali injury.

SERPINA3K Ameliorates the Corneal Oxidative Injury Induced by 4-Hydroxynonenal.

We previously demonstrated that SERPINA3K has anti-inflammatory, antiangiogenic, and antioxidant effects in corneas. Here we further investigated the effects of SERPINA3K on the corneal oxidant injury setting recently developed and induced by 4-hydroxynonenal (4-HNE). We applied the 4-HNE-induced corneal oxidant stress in cultured human corneal epithelial (HCE) cells in vitro and to the cornea of rats in vivo. The following experiments were conducted: cell counting kit 8 assay to detect cell viability; quantitative real-time PCR assay; Western blotting and immunofluorescent staining to measure gene expressions or protein levels of key reactive oxygen species (ROS)-associated factors (3-nitrotyrosine [3-NT]; nicotinamide adenine dinucleotide phosphate [NADPH]-oxidase 4 [NOX4]; superoxide dismutase [SOD]); catalase and nuclear factor [erythroid-derived 2]-like 2 [NRF2]); as well as main factors of the Wnt/β-catenin signaling pathway (p-LRP6, β-catenin and transcription factor 4 [TCF4]); histologic staining; and TUNEL staining to examine sections of rat corneas. We found that SERPINA3K concentration dependently protected cell viability, decreased levels of ROS marker 3-NT, suppressed NOX4, and upregulated SOD and catalase. Furthermore, SERPINA3K inhibited the activation of the ROS pathway NRF2 and its downstream factors, NAD(P)H dehydrogenase (quinone) 1 (NQO1) and heme oxygenase 1 (HO1), and also suppressed the activation of the Wnt signaling pathway p-LRP6, β-catenin, and TCF4 in HCE cells treated with 4-HNE. Meanwhile, SERPINA3K ameliorated the oxidant injury of rat corneas induced by 4-HNE and downregulated ROS systems and the Wnt/β-catenin pathway. Our findings show that SERPINA3K protected the oxidant damage induced by 4-HNE in the cornea and its underlying mechanism was through suppression of the ROS system and inhibition of the activated Wnt/β-catenin signaling pathway.

The Potential Protective Role of Hesperidin Against Capecitabine-Induced Corneal Toxicity in Adult Male Albino Rat. Light and Electron Microscopic Study

Background: Capecitabine is a chemotherapeutic agent widely used for the treatment of malignancies. Ocular disorders have been reported with therapy. Hesperidin is a naturally occurring compound derived mainly from citrus fruits and has a wide range of pharmacological activities and a proposed role in combating many ocular diseases.Aim: To evaluate the potential protective role of hesperidin against the corneal toxicity caused by in adult male albino rats.Material and Methods: Thirty-six adult male albino rats were divided into four equal groups; control group, hesperidin-treated group (50 mg/kg), capecitabine-treated group (40 mg/kg), and combination-treated capecitabine and hesperidin–treated group. Animals were orally administered once daily for one month. Specimens from the cornea were processed for light and electron microscopy. Immunohistochemical study was performed using antibodies against p53.Results: Specimens from capecitabine-treated animals showed significant decrease of epithelial thickness. The corneal epithelial cells showed nuclear alteration and vacuolated cytoplasm. The stromal collagen fibers were irregularly-arranged and widely separated with neovascularization and mononuclear cellular infiltration. Ultrastructurally, focal widening of the intercellular spaces, partial loss of desmosomal junctions and swollen mitochondria were observed. The immunohistochemical study showed a significant increase in p53 immunoreaction. In contrast, minimal changes were observed in rats treated concomitantly with both and hesperidin, with a non significant increase in the immunoreactions.Conclusion: Capecitabine induced structural changes in cornea of adult albino rat that could be ameliorated by concomitant treatment with hesperidin.

Short-Term Effects of Y-27632, a Rho-Associated Protein Kinase Inhibitor, on Chromatin Supraorganization and DNA Amount in Epithelial Cells of the Rat Cornea and Limbus.

To assess the short-term effects of instilling Y-27632, an inhibitor of Rho/Rho-associated protein kinases, on the chromatin supraorganization and DNA amount of corneal and limbal epithelial cells of healthy rats. Longitudinal sections (7 μm) of enucleated eyes of healthy rats that received, by instillation, balanced salt solution with or without 10 mM of Y-27632 daily for 7 or 15 days, were subjected to the Feulgen reaction. Feulgen-stained nuclei of corneal and limbal epithelial cells were studied by microscopy and video image analysis to establish the nuclear size (area and perimeter), supraorganization of chromatin (texture and degrees of condensation), and the Feulgen-DNA amount. Instillation of Y-27632 for up to 15 days did not change the size of the nucleus or the chromatin texture of corneal and limbal epithelial cells. Samples treated with Y-27632 for 7 days showed condensed chromatin and a high Feulgen-DNA amount. Both corneal and limbal epithelium showed the presence of near-tetraploid nuclei corresponding to cells in the S and G2 phases of the cell cycle. The degrees of condensation and Feulgen-DNA amount of the nuclei of epithelial cells of the cornea and limbus of eyes from rats receiving Y-27632 for 15 days did not differ from control (no drug). Changes in chromatin supraorganization and DNA amount, such as seen in this study, are indicative of cell proliferation and do not seem to be associated with disturbances in gene activity and transcription of DNA.

Regional differences in glutathione accumulation pathways in the rat cornea: Mapping of amino acid transporters involved in glutathione synthesis

In this study we have sought to complete the identification and localisation of uptake pathways involved in accumulating precursor amino acids involved in GSH synthesis in the rat cornea. To do this, we performed reverse transcription PCR (RT-PCR) to identify the Excitatory Amino Acid Transporters (EAAT 1–5) responsible for glutamate uptake, and glycine transporters (GLYT 1–2) at the transcript level. Western blotting was used to verify protein expression, while immunolabelling of sagittal sections was used to localise transporters to the different layers of the cornea. Immunolabelling of en face sections was used to examine the subcellular distribution of proteins in the corneal endothelium. Our findings revealed EAAT 1–5 and GLYT 1–2 to be expressed at the transcript and protein level in the rat cornea. Immunohistochemistry revealed all amino acid transporters to be localised to the epithelium. In the majority of cases, labelling was restricted to the epithelium, and labelling absent from the stroma or endothelium. However, EAAT 4 and GLYT 2 labelling was detected in the stroma with EAAT 4 labelling also present in the endothelium. Overall, the identification of amino acid transporters strongly supports the existence of an intracellular GSH synthesis pathway in the rat corneal epithelium. This suggests that regional differences in GSH accumulation pathways exist, with direct uptake of GSH and intracellular synthesis of GSH restricted to the endothelial and epithelial cell layers, respectively. This information is important in the design of targeted strategies to enhance GSH levels in specific layers of the cornea to prevent against oxidative damage, corneal swelling and loss of corneal transparency.

Distribution of lanosterol synthase and lanosterol in cornea, lens and retina tissue of rats

Background Researches showed that triterpenoids, with a similar structure to lanosterol, has therapeutical effect on many systemic diseases, and lanosterol was determined to have a therapeutical effect on cataract recently.However, how the lanosterol plays effects on other eye diseases is still unelucidated.Understanding the distribution of lanosterol in ocular tissue is helpful for us to elucidate the relationship of lanosterol with eye diseases. Objective This study attempted to investigate the distribution of lanosterol synthase (LSS) and lanosterol in cornea, lens and retina tissue of rats and offer a basis for the targeting treatment of eye diseases. Methods Fifteen SPF male SD rats were sacrificed by excessive anesthesia to obtain the eyeballs.The relative expressions of LSS protein and gene in the cornea, lens and retina tissue of the rats were detected by Western blot and reverse transcription (RT)-PCR, respectively.Immunofluorescence staining technology was used to locate the distribution of LSS in cornea, lens and retina tissue.The contents of lanosterol in the cornea, lens and retina tissue were analyzed by liquid chromatograph mass spectrometer (LC-MS). Results No LSS protein and mRNA was expressed in the retinal tissue in normal rats.The mean relative expression of LSS protein in the lens and cornea was 0.43±0.05 and 0.25±0.03, respectively, showing a significant difference between them (t=-5.35, P<0.01). The relative expression of LSS mRNA was 0.51±0.04 and 0.29±0.02 in the lens and cornea, respectively, with a stronger expression in the lens in comparison with the cornea (t=-8.34, P<0.01). Immunofluorescence staining showed that LSS primarily located in corneal epithelial layer, stromal layer and endothelial layer as well as lens epithelial cells and shallow cortex layer and hardly expressed in retina, and no co-expression of LSS with the neuron marked by NeuN and the Muller cell marked by glutamine synthetase (GS) in retinal tissue.LC-MS analysis revealed that the contents of lanosterol in lens and cornea was (24.37±2.91)ng/mg and (5.31±0.58)ng/mg, respectively, with a significant difference between them (t=-11.13, P<0.01). Conclusions LSS and lanosterol extensively distribute in cornea and lens of normal rats, but not in retina tissue.These results offer new strategies for the target treatment of relevant eye diseases. Key words: Lanosterol/metabolism; Lanosterol synthase; Cornea; Lens, crystalline; Retina; Cataract; Rat, SD