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  • Scholz, M
  • Pigment Epithelium of Eye
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  • 1
    Language: English
    In: Trends in Microbiology, 2003, Vol.11(4), pp.171-178
    Description: Human cytomegalovirus (HCMV) retinitis frequently occurs in severely naturally and iatrogenically immunocompromised patients. It has been shown that the immune-privileged retinal pigment epithelium (RPE) is a major site of persistent HCMV. Recently, evidence has accumulated to show that HCMV immediate early (IE) gene expression in RPE cells deviates ocular antiviral inflammation via FasL. Moreover, unlike in other cell types, the HCMV major IE1/2 enhancer promoter (MIEP) resists activation by proinflammatory stimuli mediated by the transcription factor NF- Kappa B. However, tumor necrosis factor- alpha (TNF- alpha ) and interferon- gamma (IFN- gamma ) found at elevated levels in transplant recipients and AIDS patients with retinitis sensitize RPE cells and other retinal cells to FasL-mediated apoptosis, thus contributing to retina destruction and necrosis rather than inflammation. These specific features of RPE cells in conjunction with deregulated immune responses of immunocompromised patients seem to contribute to virus persistence and pathogenesis within the immune-privileged ocular retina.
    Keywords: Biology
    ISSN: 0966-842X
    E-ISSN: 1878-4380
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  • 2
    Language: English
    In: International Journal of Molecular Medicine, February 2004, Vol.13(2), pp.327-331
    Description: Recently, we reported that thrombin specifically stimulates protease-activated receptor-1 (PAR-1) signaling in RPE entailing inhibition of Sp1 dependent HCMV replication. We now studied whether thrombin modulates the expression of the proinflammatory cytokine/chemokines IL-6 and IL-8 in mock- and cytomegalovirus-infected human retinal pigment epithelial cells (RPE). Our data show that thrombin/PAR-1 stimulates IL-6 and IL-8 gene transcription and protein secretion in both mock- and HCMV-infected RPE. Thrombin/PAR-1-mediated signaling stimulated PKC and NF-κB-dependent IL-6 and IL-8 gene expression via phosphoinositide 3-kinase and further downstream via p42/44 and p38 MAPKs. Thus, thrombin/PAR-1-mediated IL-6/IL-8 gene expression is uncoupled from Sp1 inhibition and may support proinflammatory pathomechanisms probably involved in hemorrhage/HCMV retinitis progression.
    Keywords: Cytomegalovirus Infections -- Metabolism ; Interleukin-6 -- Genetics ; Interleukin-8 -- Genetics ; Pigment Epithelium of Eye -- Metabolism ; Thrombin -- Metabolism;
    ISSN: 1107-3756
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  • 3
    Language: English
    In: Investigative ophthalmology & visual science, February 2006, Vol.47(2), pp.645-51
    Description: In addition to neuroinvasive disease, West Nile virus (WNV) infection is frequently associated with self-limiting chorioretinitis and vitritis. However, the mechanisms of ophthalmic WNV infection are rarely investigated, in part because of the lack of reliable in vitro models. The authors therefore established the first model of ocular WNV infection and investigated interaction of WNV with IFN signal-transduction mechanisms. Human retinal pigment epithelial (RPE) cells were infected with WNV strain NY385-99 at a multiplicity of infection of 5. Virus replication was evaluated by virus titers at different times after infection. The susceptibility of RPE cells to WNV infection was confirmed by transmission electron microscopy. IFN-beta expression was assessed by quantitative real-time PCR and by measurements of antiviral activity in cell culture supernatants. IFN signaling was evaluated by phosphorylation of transducer and activator of transcription 1 and 2 (STAT1/2) proteins, with immunoblot analysis. RPE cells appeared to be highly sensitive to WNV infection. Maximum viral titers were found 24 hours after infection, followed by a continuous decline during the course of infection. WNV infection of RPE cells was followed by increased IFN-beta expression associated with IFN signaling and subsequent inhibition of WNV replication. In this study, the first cell culture model of ophthalmic WNV infection was developed and characterized in RPE cells, and the molecular mechanisms of WNV infection were studied. The data suggest that WNV induces a general antiviral state in RPE cells. This general antiviral state correlates with WNV-induced IFN signaling in retinal cells.
    Keywords: Interferon-Beta -- Biosynthesis ; Pigment Epithelium of Eye -- Virology ; Signal Transduction -- Physiology ; West Nile Virus -- Physiology
    ISSN: 0146-0404
    E-ISSN: 15525783
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  • 4
    Language: English
    In: Medical Microbiology and Immunology, 2004, Vol.193(4), pp.195-203
    Description: Human cytomegalovirus (HCMV) retinitis causing retinal detachment and destruction of the blood-retina barrier is closely related to retinal hemorrhage/coagulation. However, the effects of procoagulants on HCMV (re)activation in retinal cells have not been investigated yet. Therefore, we studied whether thrombin modulates the expression of HCMV immediate early (IE) and late (L) genes in cultured human retinal pigment epithelial cells (RPE). Thrombin specifically stimulated the protease-activated receptor-1 (PAR-1) on RPE and, surprisingly, inhibited basal and 12,0-tetradecanoylphorbol 13-acetate-stimulated HCMV IE gene expression in infected RPE. On the other hand, HCMV strongly induced Sp1 DNA binding activity, which was prevented by thrombin/PAR1-mediated Sp1 hyperphosphorylation. Our data suggest that thrombin/PAR-1 may inhibit Sp1-dependent HCMV replication, which might be an important regulatory mechanism for HCMV persistence and replication in RPE.
    Keywords: Human cytomegalovirus ; Infectious immunity virus ; Retina ; Signal transduction ; Transcription factors
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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