Topical nerve growth factor attenuates streptozotocin-induced diabetic cataracts via polyol pathway inhibition and Na+/K+-ATPase upregulation

The purpose of this study was to investigate whether and how topical nerve growth factor (NGF) attenuates streptozotocin (STZ)-induced diabetic cataracts in vivo. Rats were randomly divided into three groups, including the normal control rat group, STZ-induced diabetic cataract rat group (DM group), and STZ-induced diabetic cataract rat group treated with 200 mu g/mL recombinant rat beta-NGF (DM + NGF group). Cataract formation was evaluated by portable slit lamp biomicroscopy following pupil dilation at 8 weeks. The expression levels of NGF, aldose reductase (AR), and Na+/K+-ATPase in the lens epithelial cells (LECs) of the three groups were measured in the presence or absence of topical NGF. TUNEL-positive LECs were quantified to determine if hyperglycemia caused LEC apoptosis. At 8 weeks, the mean cataract score in the control group was significantly lower than that in DM and DM + NGF groups, and the score in the DM + NGF group was significantly lower than that in the DM group. At the equatorial zone and anterior central zone of lens, NGF and Na+/K+-ATPase expression levels were significantly decreased in the DM group; however, they were partially restored in the DM + NGF group. At the equatorial zone and anterior central zone of lens, AR expression and TUNEL-positive apoptotic LECs were significantly increased in the DM group compared with the control group, however, they were significantly decreased in the DM + NGF group. In conclusion, topical NGF could delay the progression of diabetic cataracts by attenuating polyol pathway activation and increasing Na+/K+-ATPase protein levels

Corneal Epithelial Removal with a Newly Designed Epithelial Brush

This study aimed to evaluate and compare the effectiveness of a newly developed epithelial removal brush with conventional methods in a rabbit model of corneal epithelial defects. The corneal epithelia of thirty-seven rabbits were removed by three different methods including blades (blade group), newly developed epithelial brushes (Ocu group), and conventional rotating brushes (Amo group). The defect area was measured with light microscopy immediately and at 4, 18, 24, and 50 hours after removal. Corneas were obtained immediately and at 24 and 50 hours and subjected to hematoxylin and eosin (H&E) and immunofluorescence staining using proliferating cell nuclear antigen (PCNA) and phosphorylated heat shock protein 27 (pHSP27) antibodies. The residual stromal surface was observed by scanning electron microscopy (SEM). In the Ocu group, epithelia were significantly recovered at 18, 24, and 50 hours compared with immediately after removal, and in the blade and Amo groups, epithelia were significantly recovered only at 50 hours after epithelial removal. The expression levels of PCNA and pHSP27 did not differ among three groups. There was significantly more inflammatory cell infiltration in the blade group than in the other groups. SEM showed a more regular and uniform residual stromal surface in the Ocu group than in the other groups. The newly developed epithelial brush showed better polishing ability and led to earlier significant epithelial recovery and a more regular and uniform stromal surface than conventional methods in this rabbit model of epithelial defects. Accumulation of clinical data is expected to expand the scope of application of new brushes for laser surface ablation

Anti-inflammatory and anti-apoptotic effects of N-acetylcysteine in diabetic rat corneal epithelium

● AIM: To characterize the anti-inflammatory and antiapoptotic effects of N-acetylcysteine (NAC) in streptozotocin (STZ)-induced diabetic rat corneal epithelium and human corneal epithelial cells (HCECs) exposed to a high-glucose environment. ● METHODS: HCECs were incubated in 0, 5, 50 mmol/L glucose medium, or 50 mmol/L glucose medium with NAC for 24h. Diabetes was induced in rats by intraperitoneal injection of 65 mg/kg STZ and some of these rats were topically administered NAC to corneas with 3 mice per group. We characterized receptor for advanced glycation end-products (RAGE) expression using immunofluorescence, and interleukin (IL)-1β and cleaved caspase-3 (CCAP-3) expression using immunohistochemistry. Circulating tumor necrosis factor (TNF)-α concentration was measured by ELISA and cleaved poly-ADP ribose polymerase (PARP) concentration was quantified by Western blotting. Apoptotic cells were detected using TUNEL assay and annexin V and propidium iodide staining. ● RESULTS: Diabetic rats had higher expression of RAGE (2.46±0.13 fold), IL-1β, and CCAP-3 in apoptotic cells of their corneas than control rats. The expression of RAGE (1.83±0.11 fold), IL-1β, and CCAP-3, and the number of apoptotic cells, were reduced by topical NAC treatment. HCECs incubated in 50 mmol/L glucose medium showed high concentrations of TNF-α (310±2.00 pg/mL) and cleaved PARP (7.43±0.56 fold), and more extensive apoptosis than cells in 50 mmol/L glucose medium. However, the addition of NAC reduced the concentrations of TNF-α (153.67±2.31 pg/mL) and cleaved PARP (5.55±0.31 fold) and the number of apoptotic cells. ● CONCLUSION: NAC inhibits inflammation and apoptosis in the corneas of diabetic rats and HCECs maintained in a high-glucose environment