Contribution of corneal neovascularization to dendritic cell migration into the central area during human corneal infection.

Compared with the peripheral corneal limbus, the human central cornea lacks blood vessels, which is responsible for its immunologically privileged status and high transparency. Dendritic cells (DCs) are present in the central avascular area of inflamed corneas, but the mechanisms of their migration to this location are poorly understood. Here, we investigated the contribution of vessel formation to DC migration into the central cornea, and analyzed the DC chemotactic factors produced by human corneal epithelial (HCE) cells. Using human eyes obtained from surgical procedures, we then assessed vessel formation, DC distribution, and activin A expression immunohistochemically. The results demonstrated increased numbers of vessels and DCs in the central area of inflamed corneas, and a positive correlation between the number of vessels and DCs. Activin A was expressed in the subepithelial space and the endothelium of newly formed blood vessels in the inflamed cornea. In infected corneas, DCs were present in the central area but no vascularization was observed, suggesting the presence of chemotactic factors that induced DC migration from the limbal vessels. To test this hypothesis, we assessed the migration of monocyte-derived DCs toward HCE cell supernatants with or without lipopolysaccharide (LPS) stimulation of HCE cells and inflammatory cytokines (released by HCE cells). DCs migrated toward tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and activin A, as well as LPS-stimulated HCE cell supernatants. The supernatant contained elevated TNF-α, IL-6, and activin A levels, suggesting that they were produced by HCE cells after LPS stimulation. Therefore, vessels in the central cornea might constitute a DC migration route, and activin A expressed in the endothelium of newly formed vessels might contribute to corneal vascularization. Activin A also functions as a chemotactic factor, similar to HCE-produced TNF-α and IL-6. These findings enhance our understanding of the pathophysiology of corneal inflammation during infection.

Three-dimensional imaging of the inner limiting membrane folding on the vitreomacular interface in diabetic macular edema.

PURPOSE: To report the findings of fine folds on the retina obtained by spectral-domain optical coherence tomography (OCT). METHODS: A retrospective non-comparative case series; 26 eyes of diabetic macular edema (DME) patients who underwent vitrectomy were observed using three-dimensional (3D) images of OCT preoperatively and postoperatively. The specimens were investigated immunohistochemically. RESULTS: Using only tomography, non-tractional vitreoretinal interfaces were observed in 15 eyes and tractional vitreoretinal interfaces in the other 11 eyes. Using 3D imaging, we observed fine folds in 11 eyes among 15 cases showing non-tractional interfaces. Based on these findings, the state of the vitreoretinal interface was classified into 3 patterns. Group 1, both tomography and 3D imaging showed smooth retinal surfaces. Group 2, tomography showed a smooth retinal surface, but 3D imaging showed fine folds on the retina. Group 3, both tomography and 3D imaging showed a tractional vitreoretinal interface with an obvious epiretinal membrane and/or taut posterior vitreous cortex. The fine folds in group 2 disappeared and macular edema improved after inner limiting membrane (ILM) peeling, and the CRT of groups 2 and 3 reduced significantly. The fine folds were confirmed to involve the ILM because type IV collagen expression was detected in the surgically obtained specimens. CONCLUSION: We observed tangential fine folds of the ILM. These were detected by using only 3D imaging, and might be useful for investigating the optimal indication of vitrectomy for DME.

Hyaluronan production and hyaluronan synthase expression in three human conjunctiva-derived cell strains.

PURPOSE: The conjunctiva maintains the health of the ocular surface by protecting the eye from pathogen invasion, injury, and dryness. In this study, we investigated the regulation of hyaluronan (HA) synthesis by cytokines in conjunctiva-derived cells. METHODS: Cultured primary cells derived from human conjunctivas that had been removed as surgical specimens were transfected with an immortalizing gene (human papilloma virus 16 E6/E7). To compare the biological features of the primary and immortalized cells, we assessed their morphological features and gene expression patterns. We also examined the effects of inflammatory cytokines on hyaluronan synthase (HAS) expression and HA production. RESULTS: Three conjunctiva-derived cell strains were established and could be passaged up to 15 times. All strains expressed ß2MG and KRT13 transcripts, highly expressed in conjunctival epithelial cells. HA production and expression of the three HAS isoforms were detected in the cell strains; however, cytokine treatment had no significant effect on HA production or HAS isoform expression. CONCLUSIONS: We succeeded in deriving three human cell strains from conjunctival tissue. In the conjunctiva-derived cell strains, HA production and HAS mRNA expression were stable and were not changed by either TGF-ß or PDGF-BB.

Cloning and characterization of human vitreous tissue-derived cells.

PURPOSE: Previously, we established a porcine vitreous tissue-derived hyalocyte cell line (PH5) and investigated the regulation of hyaluronan synthesis in these cells by cytokines. The objective of the current study was to establish human vitreous tissue-derived cells and to compare their characteristics with those of PH5 cells. METHODS: Human vitreous specimens from two patients were cultured in the presence of 10% foetal bovine serum and immortalized by infection with human papilloma virus 16 genes E6 and E7. We used reverse transcription polymerase chain reaction (RT-PCR) to analyse and compare the expression profiles for several genes in the human vitreous tissue-derived cells and PH5 cells. To investigate the regulation of hyaluronan production in response to cytokine stimulation, the expression of hyaluronan synthase isoforms was examined using RT-PCR, and hyaluronan production was measured using enzyme-linked immunosorbent assay (ELISA). RESULTS: Two types of cells, HV64 and HV65, were derived from human vitreous tissue. The HV64 and HV65 cell-doubling times were 58 r and 76 hr, respectively. The cells expressed messenger RNA (mRNAs) encoding collagen type I α1 (COL1A1), collagen type II α1 (COL2A1), CD11b, CD14, CD68, CD204 and CD206 but did not express mRNA for glial fibrillary acidic protein (GFAP). Cytokine stimulation did not induce the expression of hyaluronan synthase mRNA or the production of hyaluronan. In contrast, mRNAs for GFAP and hyaluronan synthase-2 were expressed in the porcine PH5 cells, and treatment with transforming growth factor-ß1 and/or platelet-derived growth factor-BB induced the production of hyaluronan in PH5 cells. CONCLUSION: The new human vitreous tissue-derived cells have macrophage-like characteristics and are different from our previously developed porcine hyalocyte cells. These human vitreous tissue-derived cells might be useful for studies of human intraocular diseases.

Cotylenin A inhibits cell proliferation and induces apoptosis and PAX6 mRNA transcripts in retinoblastoma cell lines.

PURPOSE: Retinoblastoma, a childhood cancer of the retina, is caused by inactivation of the tumor suppressor gene retinoblastoma (RB). Cotylenin A (CN-A), a novel fusicoccane-diterpene glycoside, accelerates the differentiation of several types of myeloid cell lines and is a candidate for a new type of anticancer therapeutic agent with this effect. However, whether CN-A has the same effect on retinoblastoma cells is unknown. We studied the response of two retinoblastoma cell lines, Y-79 and WERI-Rb-1, to CN-A. METHODS: We studied the response of two retinoblastoma cell lines to CN-A with respect to cell growth, apoptosis, morphology, mRNA, protein expression analysis of specific genes (N-myc, cyclin-dependent kinase inhibitor 1A [P21], paired box gene 6 [PAX6], and rhodopsin [RHO]), and activity of three PAX6 promoters (P0, P1, and Palpha). RESULTS: CN-A inhibited cell proliferation and induced apoptosis via caspase activity in the two retinoblastoma cell lines. In addition, CN-A induced mRNA expression of P21, PAX6, and RHO and protein expression of P21. In Y-79 cells, PAX6 P1 promoter was activated by CN-A. In WERI-Rb-1 cells, PAX6 P0, P1, and Palpha promoter were activated by CN-A. CN-A decreased mRNA and protein expression of N-myc in two retinoblastoma cell lines. CONCLUSIONS: The responses of retinoblastoma cells to CN-A include inhibition of cell growth, induction of apoptosis, and the potential to change neuroblastoma characteristics of retinoblastoma cells.

Association of PDGF-BB-induced thrombomodulin with the regulation of inflammation in the corneal and scleral stroma.

PURPOSE: The responses of corneal and scleral stromal cells to platelet-derived growth factor (PDGF)-BB were assessed and inflammatory reactions in the cornea and sclera were investigated. METHODS: Primary cultures of cells obtained from human subjects and strains derived from human corneal or scleral stromal cells (Cs3 and Sc1, respectively) were used. Changes in gene expression after 24 hours of exposure to 10 ng/mL PDGF-BB were analyzed with an Sc1 DNA microarray. The upregulation of several genes in Cs3 and Sc1 was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. The expression of bioactive factors was detected immunohistochemically in nine different clinical specimens. RESULTS: DNA microarray analysis revealed that the gene encoding thrombomodulin (TM) was induced in Sc1 by PDGF-BB. RT-PCR confirmed that TM expression at the mRNA level was increased in both corneal and scleral stromal cells. At the protein level, TM expression was increased in scleral stromal cells, but not in corneal cells, and TM was detected in both the membrane and cytoplasmic compartments. TM was detected immunohistochemically in inflamed scleral and several corneal specimens. After TM stimulation, interleukin (IL)-18 transcription was increased in Sc1. CONCLUSIONS: PDGF-BB induced TM mRNA expression in scleral and corneal stromal cells, but Western blot analysis revealed the increase in TM expression only in the scleral cells. TM induced IL-18 in scleral stromal cells. A cascade involving these biologically active factors may regulate scleral and corneal inflammation. The results also reveal differences in the biological response of scleral and corneal stromal cells.

The in vitro response of human retinal endothelial cells to cytokines and other chemically active agents is altered by coculture with vitreous-derived hyalocytes.

BACKGROUND: Ocular angiogenesis is regulated by polypeptides including cytokines, which are known to affect vascular endothelial cells. We have reported that hyalocytes interact with vascular endothelial cells, and some cytokines affect these interactions. AIMS: To determine the effect of various chemically active agents on the viability of endothelial cells alone and cocultured with hyalocytes. METHODS: The viability of human retinal endothelial cells (HRECs) was determined after exposure to IL-1alpha, IL-1beta, IL-6, TNFalpha and VEGF using the MTT assay. These results were compared to the viability when the HRECs were cocultured with porcine hyalocytes that had been exposed to different types of cytokines. The effects of bevacizumab, fenofibrate and dexamethasone on the viability of HRECs in coculture with hyalocytes were also assessed. RESULTS: Ten micrograms/millilitre of bevacizumab decreased the percentage of living HRECs stimulated by VEGF without hyalocytes, but with the hyalocytes, 100 microg/ml of bevacizumab was required to decrease the percentage of viable HRECs stimulated by VEGF. Fenofibrate, at 5 microg/ml, decreased the viability of HRECs stimulated by IL-1beta and VEGF without hyalocytes but could not decrease the viability of HRECs cocultured with hyalocytes. Dexamethasone, at 50 microg/ml, decreased the viability of HRECs stimulated by IL-1alpha, IL-1beta, IL-6 and VEGF without hyalocytes but could not decrease the viability of HRECs cocultured. CONCLUSIONS: Coculturing HRECs with vitreous-derived hyalocytes depressed the effects of cytokines, bevacizumab, fenofibrate and dexamethasone. This suggests that the vitreal hyalocytes may play a role in pathogenic endothelial cell proliferation in vivo. Future studies to better understand this pathobiology should utilize coculture systems of HRECs and vitreal hyalocytes.

Cloning and characterization of cell strains derived from human corneal stroma and sclera.

PURPOSE: To establish human corneal stroma- and sclera-derived cells as models for studying diseases of the anterior segment of the eye. METHODS: Using a recombinant retrovirus system, we transfected human papilloma virus 16 E6 and E7 (HPV16 E6/E7) into human corneal stroma- and sclera-derived cells. The primary cells and established cell strains were characterized by assessing the mRNA expression of collagen, matrix metalloproteinase, and tissue inhibitor of metalloproteinase by reverse transcription-polymerase chain reaction. We also examined the effects of inflammatory cytokines on hyaluronan synthase expression and hyaluronan products. RESULTS: Both a corneal stroma-derived cell strain, Cs3, and a sclera-derived cell strain, Sc1, were obtained, and both cell strains could be passaged up to 25 times. The mRNA expression pattern observed in the primary cells was identical to that observed in the cell strains. Hyaluronan synthase 1 and 2 mRNAs were increased by transforming growth factor beta and platelet-derived growth factor BB. Significant differences were observed between the hyaluronan products with and without cytokine treatment. CONCLUSION: Cell strains derived from corneal stroma and sclera fibroblast cells can be established using HPV16 E6/E7 immortalized genes of the same origin. The phenotypic cell characteristics did not change after transfection, immortalization, or successive passages in culture.

Trichostatin A-induced TGF-beta type II receptor expression in retinoblastoma cell lines.

PURPOSE: Retinoblastoma, an intraocular malignant tumor of childhood, is caused by a mutation in the retinoblastoma tumor-suppressor gene RB. Retinoblastoma cells are thought to be resistant to transforming growth factor-beta (TGF-beta) because they do not express the TGF-beta type II receptor (TbetaR-II). In several tumor cell lines, trichostatin A (TSA), a potent inhibitor of histone deacetylase, induces expression of the TbetaR-II gene. The objective of the present study was to determine the effects of TSA on TbetaR-II gene expression in retinoblastoma cells. METHODS: Four retinoblastoma cell lines were transfected with a TbetaR-II promoter-luciferase reporter construct and analyzed for the effect of TSA on TbetaR-II mRNA expression, TbetaR-II promoter activity, transforming growth factor (TGF)-beta-related signal transduction, and cell growth using RT-PCR, Western blot analysis, chromatin immunoprecipitation, luciferase activity assay, and cell viability assays. RESULTS: TSA treatment induced the expression of TbetaR-II mRNA, activated the TbetaR-II promoter, and inhibited cell growth in the examined retinoblastoma cell lines. It did not restore TGF-beta-related signaling, however. CONCLUSIONS: These data show that TSA induces the expression of TbetaR-II mRNA and activates the TbetaR-II promoter in retinoblastoma cells. However, TSA treatment alone was insufficient to restore TGF-beta signaling in these cell lines. The inhibitory effect of TSA on cell growth may be unrelated to its effect on TbetaR-II expression.

Interactions between vitreous-derived cells and vascular endothelial cells in vitreoretinal diseases.

PURPOSE: This study aimed to investigate the roles played by vitreous-derived cells in the pathogenesis of vitreoretinal vascular diseases. METHODS: The vitreous was removed from porcine eyes and small pieces were cultured from which vitreous-derived cells were isolated. Polymerase chain reaction and ELISA were performed to determine the expression of vascular endothelial growth factor (VEGF) and interleukin 6 (IL-6) at the mRNA and protein levels, respectively. The viability of human retinal endothelial cells (HRECs) exposed to vitreous-derived cells was assessed by MTT assay. RESULTS: Expression of the mRNA and protein of VEGF and IL-6 was increased by exposing the porcine vitreous-derived cells (PVDCs) to interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta) and tumour necrosis factor alpha (TNFalpha), but not to VEGF or IL-6. The percentage of living human vascular endothelial cells was increased by including VEGF and IL-6 in the culture media. The viability of HRECs was affected by co-culturing them with PVDCs that had been exposed to IL-1alpha, IL-1beta, IL-6, TNFalpha and VEGF. CONCLUSIONS: Porcine vitreous-derived cells are stimulated by IL-1alpha, IL-1beta and TNFalpha, and produce VEGF and IL-6, which then enhance the proliferation of vascular endothelial cells. This network, including the cytokines and different types of cells, may contribute to the pathogenesis of proliferative vitreoretinal diseases.

Activin inhibits cell growth and induces differentiation in human retinoblastoma y79 cells.

PURPOSE: Activin is a member of the transforming growth factor-beta (TGF-beta) superfamily and exerts certain effects on differentiation and apoptosis. We investigated the effects of activin on retinoblastoma cell line. MATERIALS AND METHODS: We used retinoblastoma cell line Y79. Intracellular signal transduction of activin was investigated with RT-PCR, immunofluorescence study, and luciferase reporter assay. The effect of activin on cell growth was examined with fluorescence cell viability assays. To determine the effect of activin on apoptosis, a TUNEL assay and an immunofluorescence study of cleaved PARP were performed. The effect of activin on cell differentiation was examined with RT-PCR and Western blotting. RESULTS: Intracellular signal transduction of activin was confirmed in Y79 cells. Activin inhibited Y79 cell growth. Activin induced the expression of neural retina leucine zipper (Nrl) at the mRNA and protein levels. CONCLUSIONS: Nrl is a specific gene in rod photoreceptor development and is a gene indispensable to differentiation into rod photoreceptors, so the present results suggest that activin affects the differentiation of retinoblastoma cells into rod photoreceptor cells.

Hyaluronan production regulation from porcine hyalocyte cell line by cytokines.

The objective of this study were to establish a cell line derived from porcine hyalocytes and to investigate the regulation of hyaluronan (HA) synthesis in response to cytokines. After 50 passages of the cells derived from porcine vitreous tissue, a cell line was generated. The immortalized cells showed fibroblastic morphology. The cell doubling time was 56.9h. In the mRNA level, the cells expressed plate-derived growth factor (PDGF) alpha receptor, PDGF beta receptor, transforming growth factor-beta (TGF-beta) type I receptor, TGF-beta type II receptor, CD44, collagen type I, collagen type II, glial fibrillary acidic protein (GFAP), hyaluronan synthase (HAS) 2, HAS 3 and beta-actin. In the protein level, GFAP was expressed in this cell line. S-100 protein and cytokeratin were not detected. Stimulation with TGF-beta1 and/or PDGF-BB induced a marked increase in the expression level of HAS2 mRNA, and induced HA production. TGF-beta1 stimulated HAS2 expression through the signal transduction pathway including Smad 2,3,4. In summary, this report constitutes the first successful immortalization of porcine hyalocyte cells. The production of HA was induced from the generated porcine hyalocyte cell line under the stimulation of TGF-beta1 and/or PDGF-BB, which may be related to the pathogenesis of proliferative membrane formation in proliferative vitreo-retinal diseases.

Sequential Development of Cysteine Proteinase Activities and Gene Expression during Somatic Embryogenesis in Carrot.

Three bands of proteinase activity (Rf values of 0.5, 0.6, and 0.7) were detected on activity-stained gels after native gel electrophoresis of carrot (Daucus carota L. cv US-Harumakigosun) suspension cells. After the induction of somatic embryogenesis, one activity band (0.7 band) rapidly disappeared; the 0.6 band was absent at the heart-shaped embryo stage. However, the intensity of the 0.5 band increased during embryogenesis. An additional band (0.25 band) appeared after the torpedo-shaped stage. Three bands (0.25, 0.5, and 0.6) were also detected in zygotic seeds. Two activity bands (0.5 and 0.6) were classified as cysteine proteinases based on sensitivities to N-Ethylmaleimide (NEM) or L-3-trans-Carboxyoxirane-2-Carbonyl-L-Leucyl-Agmatine (E-64). To find candidate genes for the cysteine proteinases, we cloned seven cDNAs encoding putative cysteine proteinases from suspension cells and developing somatic embryos. The expression patterns of the seven genes were categorized into three types (Type A, mRNAs increase concomitantly with somatic embryogenesis; Type B, mRNAs decrease quickly in organized cells; Type C, no significant change in transcript level during somatic embryogenesis).

Gibberellin is essentially required for carrot (Daucus carota L.) somatic embryogenesis: dynamic regulation of gibberellin 3-oxidase gene expressions.

A GA biosynthesis inhibitor, uniconazole, caused many shrunken embryos when it was supplied to cultured carrot (Daucus carota L.) cells at the induction of somatic embryos. The abnormality was prevented by exogenous GA(1) or GA(4). To analyze the status of GA biosynthesis during somatic embryogenesis, expression patterns of newly isolated genes encoding GA biosynthetic enzymes, two GA 20-oxidases, three GA 3-oxidases, and two GA 2-oxidases were observed by using a semi-quantitative reverse-transcription-polymerase chain reaction with gene-specific primers. Transcript levels of GA 20-oxidases and GA 2-oxidases did not change greatly during development of the somatic embryo. On the other hand, drastic changes were found in three GA 3-oxidase genes. Strikingly, expression of a GA 3-oxidase gene, DcGA3ox2, was elevated once in somatic embryogenesis, but not in the non-induced suspension cells. The enzymatic functions of these gene products were also confirmed using recombinant proteins expressed in Escherichia coli. Our results indicate that GA biosynthesis is required for carrot somatic embryogenesis.