Memantine, Simvastatin, and Epicatechin Inhibit 7-Ketocholesterol-induced Apoptosis in Retinal Pigment Epithelial Cells But Not Neurosensory Retinal Cells In Vitro.

PURPOSE: 7-ketocholesterol (7kCh), a natural byproduct of oxidation in lipoprotein deposits is implicated in the pathogenesis of diabetic retinopathy and age-related macular degeneration (AMD). This study was performed to investigate whether several clinical drugs can inhibit 7kCh-induced caspase activation and mitigate its apoptotic effects on retinal cells in vitro. METHODS: Two populations of retinal cells, human retinal pigment epithelial cells (ARPE-19) and rat neuroretinal cells (R28) were exposed to 7kCh in the presence of the following inhibitors: Z-VAD-FMK (pan-caspase inhibitor), simvastatin, memantine, epicatechin, and Z-IETD-FMK (caspase-8 inhibitor) or Z-ATAD-FMK (caspase-12 inhibitor). Caspase-3/7, -8, and -12 activity levels were measured by fluorochrome caspase assays to quantify cell death. IncuCyte live-cell microscopic images were obtained to quantify cell counts. RESULTS: Exposure to 7kCh for 24 hours significantly increased caspase activities for both ARPE-19 and R28 cells (P < 0.05). In ARPE cells, pretreatment with various drugs had significantly lower caspase-3/7, -8, and -12 activities, reported in % change in mean signal intensity (msi): Z-VAD-FMK (48% decrease, P < 0.01), memantine (decreased 47.8% at 1 µM, P = 0.0039 and 81.9% at 1 mM, P < 0.001), simvastatin (decreased 85.3% at 0.01 µM, P < 0.001 and 84.8% at 0.05 µM, P < 0.001) or epicatechin (83.6% decrease, P < 0.05), Z-IETD-FMK (68.1% decrease, P < 0.01), and Z-ATAD-FMK (47.7% decrease, P = 0.0017). In contrast, R28 cells exposed to 7kCh continued to have elevated caspase-3/7, -8, and -12 activities (between 25.7% decrease and 17.5% increase in msi, P > 0.05) regardless of the pretreatment. CONCLUSION: Several current drugs protect ARPE-19 cells but not R28 cells from 7kCh-induced apoptosis, suggesting that a multiple-drug approach is needed to protect both cells types in various retinal diseases.

Arcuate retinotomy for the repair of large macular holes.

BACKGROUND AND OBJECTIVE: To present a case series to elucidate a novel technique that involves the creation of an arcuate retinotomy in the treatment of large macular holes after failed primary repair. PATIENTS AND METHODS: retrospective chart review. Six eyes (six patients) with large macular holes, all of which had failed primary repair, underwent 25 gauge pars plana vitrectomy revision coupled with full thickness arcuate retinotomy temporal to the macular hole and fluid-gas exchange. The main outcome measure was anatomic macular hole closure based on optical coherence tomography (OCT), with visual acuity and visual field evaluation as secondary outcome measures. RESULTS: Five of the six patients (83%) had successful hole closure with three of the six patients (50%) exhibiting improvement in visual acuity. CONCLUSION: Arcuate retinotomy is a new approach that may aide in the repair of large macular holes not otherwise amenable to closure with traditional techniques.

Effect of bevacizumab (Avastin (TM) ) on mitochondrial function of in vitro retinal pigment epithelial, neurosensory retinal and microvascular endothelial cells.

PURPOSE: To evaluate the effect of bevacizumab on the mitochondrial function of human retinal pigment epithelial (ARPE-19), rat neurosensory retinal (R28) and human microvascular endothelial (HMVEC) cells in culture. MATERIALS AND METHODS: ARPE-19 and R28 cells were treated with 0.125, 0.25, 0.50 and 1 mg/ml of bevacizumab. The HMVEC cultures were treated with 0.125, 0.25, 0.50 and 1 mg/ml of bevacizumab or 1 mg/ml of immunoglobulin G (control). Mitochondrial function assessed by mitochondrial dehydrogenase activity (MDA) was determined using the WST-1 assay. RESULTS: Bevacizumab doses of 0.125 to 1 mg/ml for 5 days did not significantly affect the MDA of ARPE-19 cells. Bevacizumab treatment at 0.125 and 0.25 mg/ml (clinical dose) did not significantly affect the MDA of R28 cells; however, 0.50 and 1 mg/ml doses significantly reduced the R28 cell mitochondrial function. All doses of bevacizumab significantly reduced the MDA of proliferating and non-proliferating HMVEC. CONCLUSION: Bevacizumab exposure for 5 days was safe at clinical doses in both ARPE-19 and R28 retinal neurosensory cells in culture. By contrast, bevacizumab exposure at all doses show a significant dose-dependent decrease in mitochondrial activity in both the proliferating and non-proliferating HMVEC in vitro. This suggests a selective action of bevacizumab on endothelial cells at clinical doses.

Suppression of thrombospondin-1 expression during uveal melanoma progression and its potential therapeutic utility.

OBJECTIVES: To determine whether expression of thrombospondin-1 (TSP1), an endogenous inhibitor of angiogenesis, is downregulated during progression of uveal melanoma and whether administration of TSP1 and/or its antiangiogenic peptides attenuate tumor growth. METHODS: Tyrosinase-SV40 T-antigens (Tyr Tag) transgenic mice were used for evaluation of TSP1 expression during tumor progression using immunohistological methods. The therapeutic potential of TSP1 on tumor progression was evaluated either by crossing Tyr Tag mice with a line of transgenic mice overexpressing TSP1 in the eye or by administration of TSP1-mimetic peptide with known antiangiogenic, antitumor activity. Tumor areas were measured in histological sections using Optima software (Media Cybernetics, Inc). RESULTS: The Tyr Tag tumors from 3-week-old mice showed significant TSP1 expression, which was dramatically downregulated in tumors from 12-week-old mice. Furthermore, the development and progression of tumor was significantly delayed in Tyr Tag TSP1 transgenic mice or Tyr Tag mice receiving TSP1-mimetic peptide (100 mg/kg/d). CONCLUSIONS: Expression of TSP1 was decreased with the angiogenic switch during progression of uveal melanoma, and TSP1 and/or its antiangiogenic peptides were effective in attenuation of tumor growth. CLINICAL RELEVANCE: Modulation of TSP1 expression and/or activity may be beneficial in treating uveal melanoma.

Postoperative visual acuity in patients with fuchs dystrophy undergoing descemet membrane-stripping automated endothelial keratoplasty: correlation with the severity of histologic changes.

OBJECTIVE: To investigate a correlation between the severity of histologic changes of the Descemet membrane in patients with Fuchs endothelial dystrophy and the best-corrected visual acuity (VA) after Descemet membrane-stripping automated endothelial keratoplasty (DSAEK). METHODS: In a retrospective study design, we created a histologic grading system based on common characteristics observed histologically among 92 DSAEK specimens sent to the University of Wisconsin Eye Pathology Laboratory with a clinical diagnosis of Fuchs dystrophy from 3 separate corneal surgeons. Cases were graded as mild, moderate, or severe on the basis of guttae dispersion, presence of a laminated Descemet membrane, presence of embedded guttae, and density of guttae. Regression models were built to study the relationship among preoperative VA, histologic findings, and best-corrected VA 6 months and 1 and 2 years after DSAEK. RESULTS: No correlation was found between the severity of histologic changes of Descemet membrane and preoperative VA. However, a correlation was noted between the preoperative and final VA. Cases with a laminated Descemet membrane but no embedded guttae (n = 8) appeared to be less responsive to DSAEK. Otherwise, the severity of histologic changes of Descemet membrane observed in patients with Fuchs corneal dystrophy after DSAEK did not show a statistically significant correlation with final VA. CONCLUSIONS: Our analysis fails to show an inverse relationship between the severity of histologic changes of the Descemet membrane and the best-corrected VA of at least 20/40 after DSAEK for Fuchs endothelial dystrophy. However, in a subset of patients with Fuchs dystrophy who develop a laminated Descemet membrane without embedded guttae, the visual recovery after DSAEK is less than expected. The laminated architecture of Descemet membrane without embedded guttae may facilitate separation between the membrane layers and, thus, incomplete removal of the recipient's Descemet membrane during DSAEK, which may then limit the postoperative visual outcome.

Sebaceous cell carcinoma of the eyelid: a rapidly enlarging lesion with massive xanthogranulomatous inflammation.

A 76-year-old man presented atypically with a 4-week history of a rapidly enlarging ulcerated nodular lesion of the left upper eyelid that was found to be sebaceous cell carcinoma. Further investigation showed no metastatic disease, and Mohs surgery was performed to resect the tumor. Histopathologic analysis showed features diagnostic of sebaceous cell carcinoma. However, most of the mass consisted of xanthomatous granulomatous inflammatory reaction vastly out of proportion with the tumor burden. The patient was spared from orbital exenteration, and no evidence of recurrence was present 6 months after resection.

Development of choroidal neovascularization in rats with advanced intense cyclic light-induced retinal degeneration.

OBJECTIVES: To study the progressive changes of intense cyclic light-induced retinal degeneration and to determine whether it results in choroidal neovascularization (CNV). METHODS: Albino rats were exposed to 12 hours of 3000-lux cyclic light for 1, 3, or 6 months. Fundus examination, fundus photography, fluorescein and indocyanine green angiography, and optical coherence tomography were performed prior to euthanization. Light-exposed animals were euthanized after 1, 3, or 6 months for histopathological evaluation. Retinas were examined for the presence of 4-hydroxy-2-nonenal- and nitrotyrosine-modified proteins by immunofluorescence staining. RESULTS: Long-term intense cyclic light exposure resulted in retinal degeneration with loss of the outer segments of photoreceptors and approximately two-thirds of the outer nuclear layer as well as development of subretinal pigment epithelium neovascularization after 1 month. Almost the entire outer nuclear layer was absent with the presence of CNV, which penetrated the Bruch membrane and extended into the outer retina after 3 months. Absence of the outer nuclear layer, multiple foci of CNV, retinal pigment epithelial fibrous metaplasia, and connective tissue bands containing blood vessels extending into the retina were observed after 6 months. All intense light-exposed animals showed an increased presence of 4-hydroxy-2-nonenal and nitrotyrosine staining. Optical coherence tomographic and angiographic studies confirmed retinal thinning and leakiness of the newly formed blood vessels. CONCLUSIONS: Our results suggest that albino rats develop progressive stages of retinal degeneration and CNV after long-term intense cyclic light exposure, allowing the detailed study of the pathogenesis and treatment of age-related macular degeneration. CLINICAL RELEVANCE: The ability to study the progressive pathogenesis of age-related macular degeneration and CNV will provide detailed knowledge about the disease and aid in the development of target-specific therapy.

Mitochondrial DNA damage induced by 7-ketocholesterol in human retinal pigment epithelial cells in vitro.

PURPOSE: To assess oxysterol-induced mitochondrial DNA (mtDNA) damage and mitochondrial dysfunction in cultured human retinal pigment epithelial cells (ARPE- 19). METHODS: ARPE-19 cultures were exposed for 6 and 24 hours to 40 microg/mL 7-ketocholesterol (7kCh), and total DNA was extracted. Long-extension polymerase chain reaction was performed to amplify the full-length mtDNA genome. The products were separated by electrophoresis on a 0.8% agarose gel stained with ethidium bromide. Superoxide and reactive oxygen/nitrogen species (ROS/RNS; hydrogen peroxide, peroxynitrite anions, and peroxyl radicals) were measured with an amine-reactive green-dye assay and 2',7'-dicholorodihydrofluorescein diacetate (H(2)DCFDA) dye assay, respectively. The changes in mitochondrial membrane potential (DeltaPsim) were measured with a cationic (green) dye assay. Western blot analysis was used to assess porins, a structural protein of the mitochondrial membranes. RESULTS: The 7kCh-treated cultures showed significant increase in ROS/RNS production (P < 0.001) compared with untreated controls, but the superoxide levels were unchanged. The 7kCh-treated ARPE-19 cultures had diminished levels of the full-length 16.2-kb mtDNA band, a 2.2-fold decrease of the DeltaPsim compared with control cultures (P < 0.001), and decreased levels of porins. CONCLUSIONS: 7kCh causes significant damage to the full-length intact mtDNA and mitochondrial dysfunction in ARPE-19 cells. These observations suggest that the mitochondria and its DNA may be targets for oxysterol-induced oxidative stress and may play a role in the pathogenesis of retinal diseases.

Effects of Benzo(e)Pyrene, a toxic component of cigarette smoke, on human retinal pigment epithelial cells in vitro.

PURPOSE: To better understand the cellular and molecular basis for the epidemiologic association between cigarette smoke and age-related macular degeneration (AMD), the authors examined the effects of Benzo(e)Pyrene (B(e)P), a toxic element in cigarette smoke, on human retinal pigment epithelial cells (ARPE-19). METHODS: ARPE-19 cells were cultured in Dulbecco modified Eagle medium containing 10% fetal bovine serum. Cells were treated for 24 hours with 1000 microM, 400 microM, 200 microM, and 100 microM B(e)P. Cell viability was determined by a trypan blue dye-exclusion assay. Activities of caspase-3/7, caspase-8, caspase-9, and caspase-12 were measured by a fluorescence image scanner, and DNA laddering was evaluated by electrophoresis on 3% agarose gel. RESULTS: The mean percentage of cell viabilities of ARPE-19 cells was decreased in a dose-dependent manner after exposure to B(e)P at the higher concentrations of 1000 microM (20.0 +/- 0.4; P < 0.001), 400 microM (35.6 +/- 6.4; P < 0.001), and 200 microM (58.7 +/- 2.3; P < 0.001) but not at 100 microM (95.9 +/- 0.7; P > 0.05) compared with the equivalent dimethyl sulfoxide (DMSO)-treated control cultures. There were significant increases in caspase-3/7, -8, -9, and -12 activities compared with the DMSO-treated controls (P < 0.001). DNA laddering revealed bands at 200-bp intervals. CONCLUSIONS: These results show that B(e)P is a toxicant to human retinal pigment epithelial cells in vitro. It causes cell death and induces apoptosis by the involvement of multiple caspase pathways.

7-Ketocholesterol activates caspases-3/7, -8, and -12 in human microvascular endothelial cells in vitro.

7-Ketocholesterol (7kCh) is a major oxysterol found associated with vascular diseases. Human microvascular endothelial cells (HMVECs) were cultured with different concentrations of 7kCh with and without inhibitors. Cell viabilities and caspase activities were assessed. 7kCh caused loss of cell viability in a dose-dependent manner. Caspases-8, -12, and -3/7 but not caspase-9 were activated by 7kCh treatment. The 7kCh-induced caspase-8 activity was blocked partially by pre-treatment with z-VAD-fmk and z-IETD-fmk, a caspase-8 inhibitor. However, pre-treatment with z-ATAD-fmk, a caspase-12 inhibitor, followed by 7kCh exposure lead to significantly increased caspase-8 activity. This suggests that caspase-8 and caspase-12 pathways have unique inhibition patterns and that caspase-12 is likely not upstream and feeding into caspase-8 but the pathways may function in parallel to each other. Caspase-3/7 activation was inhibited partially by low density lipoprotein (LDL), high density lipoprotein (HDL), z-VAD-fmk (pan-caspase inhibitor), and low doses (0.01 and 0.001 microM) of the cholesterol lowering drug, simvastatin. However, only LDL partially protected against 7kCh-induced loss of cell viability suggesting that caspase-independent pathways also contributed to the cell loss and that protection from oxysterol damage may require inhibition of multiple pathways. Moreover, our data suggest that oxysterols such as 7kCh can damage HMVECs cells in part via caspase-dependent apoptosis and may play a role in vascular and retinal diseases.

Application of second harmonic imaging microscopy to assess structural changes in optic nerve head structure ex vivo.

Glaucoma represents the second leading cause of blindness worldwide. While both age and intraocular pressure (IOP) are well-recognized risk factors for this disease, the underlying pathologic process involves the accelerated death of retinal ganglion cells (RGCs) that is associated with progressive loss of vision. The loss of RGCs has been postulated to occur primarily by injury to axons in the optic nerve head (ONH) due to its anatomic features and the mechanical vulnerability of the lamina cribrosa, the specialized ONH zone comprised of collagen beams that define the channels or pores through which axon bundles exit the eye. Recent advances in multiphoton microscopy using femtosecond lasers that generate second harmonic (SH) signals from collagen allows for direct optical imaging of the lamina cribrosa. We assess the application of SH generated microscopy (SHG) to the study of the ONH, and test the general hypothesis that increasing intraocular pressure in the same eye results in the movement of ONH collagen beams leading to distortion of the lamina cribrosa channels and compression of the axon bundles.

Caspase-8, -12, and -3 activation by 7-ketocholesterol in retinal neurosensory cells.

PURPOSE: To determine the caspase pathways involved with 7-ketocholesterol (7kCh)-induced apoptosis in rat R28 cells. METHODS: R28 cells were exposed to 7kCh with or without low-density lipoprotein (LDL) and z-VAD-fmk, a pan-caspase inhibitor. Cell viability was measured by a trypan blue dye exclusion assay. Caspase-3, -8, -9, and -12 activities were measured by fluorochrome caspase assays. ARPE-19 cells were used as control for caspase-3 inhibition experiments. RESULTS: R28 cultures showed decreased cell viability on 7kCh exposure compared with controls (P < 0.001), and this was reversed with LDL and LDL + z-VAD-fmk (P < 0.001). The 7kCh-treated R28 cultures had increased caspase-8 activity compared with controls (P < 0.001). This activity was blocked partially with LDL (P < 0.01) or LDL + z-VAD-fmk (P < 0.001) but not with z-VAD-fmk alone. Caspase-12 activity was increased after 7kCh treatment compared with controls (P < 0.01), and this activity was increased further with the addition of LDL. Caspase-3 activity in R28 cultures increased with 7kCh treatment compared with controls (P < 0.001). In R28 cultures, the z-VAD-fmk treatment did not blocked 7kCh-induced caspase-3 activity but did block activity in ARPE-19 cultures (P < 0.001). Caspase-9 was not activated by 7kCh treatment. CONCLUSIONS: In R28 cells, 7kCh-induced apoptosis involves the caspase-3 along with the caspase-8 and caspase-12 pathways. LDL partially blocked 7kCh-induced caspase-8 activity but increased caspase-12 activities, suggesting that caspase-8 and caspase-12 pathways are independent of each other. The z-VAD-fmk inhibitor blocked caspase-3 activities in the homogeneous ARPE-19 cultures but not in the heterogeneous R28 cultures.

Evaluation of in vitro effects of bevacizumab (Avastin) on retinal pigment epithelial, neurosensory retinal, and microvascular endothelial cells.

PURPOSE: To evaluate the short-term in vitro safety of bevacizumab (Avastin) in human retinal pigment epithelial (ARPE-19), rat neurosensory retinal (R28), and human microvascular endothelial (HMVECad) cells. METHODS: ARPE-19 and R28 cells were treated with 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of bevacizumab for 2, 6, and 24 hours. HMVECad cells were treated with 5 ng/mL of vascular endothelial growth factor (VEGF) and 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of either bevacizumab for 2, 6, and 24 hours or a nonspecific human purified immunoglobulin (IgG) for 24 hours. Cell viability was measured using trypan blue dye exclusion assay. RESULTS: The cell viabilities of ARPE-19 cells, R28 cells, and HMVECad cells treated with bevacizumab were not significantly different (P > 0.05) from that of untreated controls. There was no significant difference (P > 0.05) between viabilities of HMVECad cells treated with bevacizumab and IgG. CONCLUSION: This study suggests that bevacizumab, at concentrations at or above the dose normally used in clinical practice, is not toxic to human retinal pigment epithelial, rat neurosensory retinal, or human microvascular endothelial cells in vitro. This report is consistent with the recent report of lack of toxicity of intravitreal bevacizumab in rabbits as well as the lack of apparent toxicity in clinical use.