Expression of SIRT1 in choroidal neovascular membranes.

PURPOSE: SIRT1 is a deacetylase that has been shown to be instrumental in embryonic and pathologic vascular formation. The purpose of this study was to evaluate the potential role of SIRT1 in the pathogenesis of choroidal neovascularization in age-related macular degeneration. METHODS: The expression of SIRT1 was assessed via immunohistochemistry in nine excised human choroidal neovascularization membranes and seven non-age-related macular degeneration donor eyes. Enzyme-linked immunosorbent assay-based angiogenesis arrays were used to assess the potential of an SIRT1 inhibitor, nicotinamide, to reduce secretion of 10 unique proangiogenic cytokines from retinal pigment epithelial cells. RESULTS: SIRT1 was expressed more frequently in choroidal neovascularization membranes than donor eyes about vascular endothelial cells (78 vs. 29% positive cases) and retinal pigment epithelial cells (57 vs. 14% positive cases). SIRT1 inhibition in retinal pigment epithelial cells correlated with significantly decreased secretion of three potent proangiogenic cytokines: angiogenin, platelet-derived growth factor BB, and vascular endothelial growth factor A. CONCLUSION: SIRT1 levels appear elevated in human choroidal neovascularization membranes compared with control eyes. Moreover, inhibition of SIRT1 activity is correlated with decreased secretion of potent proangiogenic cytokines. Collectively, these data support a potential role for SIRT1 in the pathogenesis of neovascular age-related macular degeneration.

Choroidal neovascular membranes express toll-like receptor 3.

BACKGROUND: Recent evidence has suggested a role for toll-like receptor 3 (TLR3) in experimental models of age-related macular degeneration (AMD). To date, however, few data exist about TLR3 in human AMD. The purpose of this study was to investigate the expression of TLR3 in human choroidal neovascular (CNV) membranes. METHODS: Immunostaining for TLR3 was performed on sections of CNV membranes from 8 AMD patients and eyes from 4 donors without CNV. RESULTS: All CNV membranes expressed TLR3 in retinal pigment epithelial (RPE) cells. One was classified as having strong intensity, 5 as having moderate intensity and 2 as having weak intensity. All cases had ≥30% of the RPE cells staining for TLR3, ranging from 30 to 90%. No expression of TLR3 was observed in vascular endothelial cells or fibroblasts in any CNV membrane. In the donor eyes, the RPE cells near the ora serrata stained stronger than those at the posterior pole, where no staining was observed in 3 out of 4 cases. CONCLUSION: TLR3 was found in all CNV membranes and was expressed exclusively in RPE cells. The observed difference in RPE staining for TLR3 in donor eyes and CNV membranes suggests a possible role for this receptor in human neovascular AMD.

Clinical pathologic study of a cohort of patients with retinoblastoma from a developing country.

PURPOSE: To describe the histopathologic characteristics of all retinoblastoma biopsy specimens received at one institution. METHODS: All retinoblastoma biopsy specimens received between January 2000 and December 2005 were evaluated and a total of 109 eyes from 101 patients were studied. RESULTS: There were 9 (8.3%) well differentiated, 25 (23.0%) moderately differentiated, and 66 (60.5%) poorly differentiated retinoblastomas. The most common growth pattern was mixed, comprising 81 (74.4%) cases. Vitreous seeding, invasion of the anterior chamber, and invasion of the optic nerve beyond the lamina cribrosa, was present in 79 (72.5%), 24 (22.0%), and 44 (40.4%) eyes, respectively. The tumor was confined to the retina in only 26 (23.9%) cases, whereas 16 (14.8%) had minimal choroidal invasion, 45 (41.3%) had massive choroidal involvement, 10 (9.2%) had scleral invasion, and 11 (10.1%) had extraocular extension. CONCLUSION: In this study, the percentage of patients with choroidal and optic nerve invasion, reflecting a poor prognosis, was much higher than in previously reported North American series. However, similar findings have been described in other developing countries, where late diagnosis is common. This study emphasized the need for early diagnosis and treatment.

Control of hypercholesterolemia and atherosclerosis using the cholesterol recognition/interaction amino acid sequence of the translocator protein TSPO.

The translocator protein (18-kDa) TSPO is an ubiquitous high affinity cholesterol-binding protein reported to be present in the endothelial and smooth muscle cells of the blood vessels; its expression dramatically increased in macrophages found in atherosclerotic plaques. A domain in the carboxy-terminus of TSPO was identified and characterized as the cholesterol recognition/interaction amino acid consensus (CRAC). The ability of the CRAC domain to bind to cholesterol led us to hypothesize that this peptide could be used as an hypocholesterolemic, with potential anti-atherogenic properties, agent. We report herein the therapeutic benefit that resulted for the administration of the VLNYYVWR human CRAC sequence to guinea pigs fed with a high cholesterol diet and ApoE knock-out B6.129P2-Apoetm1Unc/J mice. CRAC treatment (3 and 30mg/kg once daily for 6 weeks) resulted in reduced circulating cholesterol levels in guinea pigs fed with 2% high cholesterol diet and ApoE knock-out B6.129P2-Apoetm1Unc/J mice. In high cholesterol fed guinea pigs, CRAC treatment administered once daily induced an increase in circulating HDL, decreased total, free and LDL cholesterol, and removed atheroma deposits in the aorta in a dose-dependent manner. The treatment also prevented the high cholesterol diet-induced increase in serum creatine kinase, total and isoforms, markers of neurological, cardiac and muscular damage. No toxicity was observed. Taken together these results support a role of TSPO in lipid homeostasis and atherosclerosis and indicate that CRAC may constitute a novel and safe treatment of hypercholesterolemia and atherosclerosis.

Expression of vascular endothelial growth factor in retinoblastoma.

OBJECTIVES: To investigate the immunohistochemical expression of vascular endothelial growth factor (VEGF) and to determine its possible association with tumor differentiation status, optic nerve and/or choroidal invasion, anterior chamber invasion, vitreous seeding, and basophilic staining of the vascular walls. METHODS: A retrospective study was performed to identify the expression of VEGF in 47 of 129 consecutive patients with retinoblastoma treated at the Ocular Pathology Laboratory of the Anatomy and Pathology Institute of the Central University of Venezuela in Caracas from January 1, 2000, through December 31, 2007. RESULTS: A positive correlation between VEGF staining intensity and time of progression and mitotic and apoptotic indexes was observed. However, no correlation was found between VEGF expression and other prognostic factors in this malignant neoplasm, including tumor stage as assessed by the Grabowski and Abramson classification. CONCLUSIONS: Although the isolated characterization of VEGF in retinoblastoma is not grounds for this protein to be considered a prognostic factor, its association with mitotic and apoptotic indexes suggests it may play a role in the progression of this disease. Thus, therapeutic targeting of VEGF in retinoblastoma may be an effective strategy to reduce tumor progression.

Cytopathological diagnosis of adult retinoblastoma in a vitrectomy specimen.

Retinoblastoma (RB) is extremely rare in adults. We describe a case of RB diagnosed by cytology in a vitrectomy specimen of a 23-year-old patient who presented with diminished visual acuity and retinal detachment in the absence of a clinically-visible mass. Cytological examination of the vitreous fluid showed clusters of loosely cohesive atypical cells with high nuclear to cytoplasmic ratio and "salt and pepper" chromatin pattern in a background of normal neuronal retinal cells. Nuclear molding was present as well as numerous apoptotic bodies. The cells were focally positive for epithelial markers and showed strong and diffuse positivity for neuroendocrine markers. Ki-67 stained 90% of the "atypical cells" nuclei, in contrast to nonneoplastic retinal neuronal cells, which were negative for the marker. A diagnosis of RB was rendered, and subsequently was confirmed in the enucleation specimen. The cytological differential diagnosis is discussed as well as the role that cytology and immunohistochemistry can play in differentiating neoplastic cells from normal retinal cellular elements in vitreous fluid specimens.

Lysyl oxidase expression and inhibition in uveal melanoma.

Lysyl oxidase is a marker of poor prognosis in several malignancies and is hypothesized to promote a migratory phenotype in hypoxic breast carcinomas. This study aims to characterize the expression of the lysyl oxidase and lysyl oxidase-like proteins in human uveal melanoma cell lines and archival choroidal melanomas using immunohistochemistry. The transcriptional control of lysyl oxidase will also be investigated under simulated hypoxic conditions using cobalt chloride. Lastly, changes in cellular proliferation and invasion will be assessed after the treatment of cell lines with beta-aminopropionitrile, a lysyl oxidase catalytic inhibitor. Retrospective analysis of lysyl oxidase expression in primary human uveal melanoma showed 82% (27 of 33) of tumors being stained positive. High lysyl oxidase expression correlated with the aggressive epithelioid cell type and was associated with shorter metastasis-free survival. Simulated hypoxia resulted in a significant increase in lysyl oxidase mRNA expression. Inhibiting lysyl oxidase's catalytic activity significantly reduced cellular invasion but had no effect on cell proliferation. Our study is the first to show lysyl oxidase expression in primary choroidal melanomas. This protein may represent a potential therapeutic target that warrants further study in this malignancy.

Expression profiling of formalin-fixed paraffin embedded primary human uveal melanomas using DASL matrices.

PURPOSE: Fresh biopsied ocular tumor tissues are difficult to obtain for the purpose of performing microarray experiments on extracted nucleic acids. Present technology allows for extraction of total RNA from formalin-fixed paraffin embedded (FFPE) tissue analyzed by the cDNA mediated Annealing Sectioning and Ligation (DASL) method. We aimed to correlate gene transcript differences between two uveal melanoma (UM) clinical-histopathological parameters (metastasis, cell type). METHODS: A total of 43 FFPE UM were used. The expression of RPL13a, a ribosomal protein gene, for each sample was used to evaluate the quality of RNA extracted from FFPE tissue. Gene expression values generated from the array were analyzed using the GeneSpring GX software (Agilent). Immunohistochemistry was used in order to validate transcriptional findings at the protein level. RESULTS: A total of 106 genes were identified with (P < 0.05, Welch ANOVA test) a difference in transcript abundance for the metastasis clinical parameter. Furthermore, we identified 64 genes with a statistically significant (P < 0.05) difference in transcript abundance between the spindle and epithelioid cell types. Each individual sample for both groups (metastasis, cell type) exhibited distinct transcriptional profiles that were separated on a PCA. Positive nuclear immunostaining for LIG4-metastasis, ErbB3-cell type was found to be associated with better patient prognosis and outcome. CONCLUSIONS: To the best of our knowledge, this is the first time that a successful retrospective analysis has been done with UM FFPE RNA. This data may lead to future customized therapeutic targets, which may improve the now unchanged mortality rate of this particular malignancy.