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  • Scholz, Martin  (14)
  • Cytomegalovirus
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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
    In: Transplantation, 1996, Vol.61(12), pp.1763-1770
    Description: Transplantation-related pathogenic factors such as ischemia or allograft-directed inflammation are associated with oxidative changes that might lead to cellular oxidative stress. The aim of this study was to investigate the impact of oxidative stress on: (1) CMV replication in cultured human endothelial cells and (2) the stimulation of endothelial cells by proinflammatory cytokines. Both pathomechanisms are known to contribute to graft rejection crises in vivo. Oxidative stress was induced in endothelial cell cultures with 10-200 μM buthionine sulfoximine. Western blotting showed a significant increase in the production of CMV-specific immediate early and late proteins in buthionine sulfoximine-treated cultures. Immunocytochemical staining suggested that this effect was caused by increased numbers of CMV antigen expressing cells (66% immediate early; 78%, late). Quantitative polymerase chain reaction for CMV-specific DNA and virus titration revealed that enhanced viral replication levels correlated with increased virion production. As a measure for the endothelial cell activation status, the surface expression of HLA-ABC and HLA-DR and adhesion molecules(ICAM-1, ELAM-1, VCAM-1) was quantified by fluorometric methods. Whereas oxidative stress alone did not modulate any surface molecule expression, the IFN-γ-mediated expression of HLA-ABC and HLA-DR and the IL-1-mediated expression of ICAM-1, but not of ELAM-1 and VCAM-1 (IL-1+TNF-α), was amplified. Interestingly, the amplification of HLA molecule expression was even higher in CMV-infected endothelial cells. This study provides evidence that oxidative stress contributes to the regulation of CMV replication, virus shedding, and the activation of endothelial cells by proinflammatory cytokines as it is observed in transplant recipients.
    Keywords: Human Cytomegalovirus ; Human Cytomegalovirus ; Endothelium ; Replication ; Oxidation ; Stress ; Man ; Endothelium ; Replication ; Oxidation ; Stress ; Man ; Viruses ; Immune Response & Immune Mechanisms ; Cytokines ; Cytokines ; Cytokines;
    ISSN: 0041-1337
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  • 3
    In: Transplantation, 1999, Vol.68(11), pp.1753-1761
    Description: BACKGROUND.: Cytomegalovirus (CMV) infection is associated with acute and chronic allograft rejection. We have recently shown that rat CMV increases portal inflammation and bile duct destruction in a model of rat liver allograft rejection. Desferrioxamine (DFO), an iron chelator and antioxidant, has recently been demonstrated to have antiviral as well as immunomodulatory effects in vitro. We therefore investigated whether DFO inhibits (a) CMV infection and (b) graft destruction in our rat model. METHODS.: One day after liver transplantation, PVG (RT1) into BN(RT1), the rats were infected with rat CMV (RCMV, Maastricht strain; 10 plaque-forming units i.p.). The effects of 100 mg/kg body weight and 200 mg/kg body weight DFO were examined. RESULTS.: In the untreated group, the grafts were uniformly RCMV culture-positive. In the group receiving 200 mg/kg DFO, RCMV replication was effectively inhibited. Inflammatory response in the graft, and especially the number of macrophages, was significantly reduced by DFO. Portal inflammation and bile duct destruction were also significantly reduced. In the untreated group, the bile duct epithelial cells were found to be strongly positive for tumor necrosis factor-α and this expression was clearly decreased by DFO. In addition, DFO significantly inhibited vascular cell adhesion molecule-1 expression on sinusoidal endothelial cells. CONCLUSIONS.: Our in vivo transplant study strongly supports the inhibitory effects of metal chelators on CMV infection and their possible usefulness in the treatment of CMV-induced pathogenic changes.
    Keywords: Adjuvants, Immunologic–Pharmacology ; Animals–Pharmacology ; Antiviral Agents–Metabolism ; Cell Adhesion Molecules–Physiology ; Cytomegalovirus–Immunology ; Cytomegalovirus Infections–Virology ; Deferoxamine–Pharmacology ; Graft Rejection–Complications ; Liver–Drug Effects ; Liver Transplantation–Immunology ; Nephritis–Pathology ; Rats–Virology ; Rats, Inbred Bn–Etiology ; Rats, Inbred Strains–Pathology ; Transplantation, Homologous–Metabolism ; Tumor Necrosis Factor-Alpha–Drug Effects ; Virus Replication–Drug Effects ; Adjuvants, Immunologic ; Antiviral Agents ; Cell Adhesion Molecules ; Tumor Necrosis Factor-Alpha ; Deferoxamine;
    ISSN: 0041-1337
    E-ISSN: 15346080
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  • 4
    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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  • 5
    Language: English
    In: Trends in Molecular Medicine, 2004, Vol.10(1), pp.19-23
    Description: Recently, the term oncomodulation has been proposed to express the ability of human cytomegalovirus (HCMV) to modify tumor cell biology, a phenomenon that is independent from transformation. Because past studies have failed to show that HCMV can transform normal human cells, HCMV has not been regarded as an oncogenic tumor virus. However, recent investigations have revealed a high frequency of HCMV in tumor cells of malignancies such as colon cancer, malignant glioma, prostatic intraepithelial neoplasia, and carcinoma. Data from experiments with HCMV-infected tumor cell lines have highlighted the oncomodulatory potential of HCMV and provided important insights into the patho- mechanisms associated with aberrant signaling pathways and transcription factor and/or tumor suppressor function of the host cell.
    Keywords: Medicine ; Biology
    ISSN: 1471-4914
    E-ISSN: 1471-499X
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  • 6
    Language: English
    In: Medical Microbiology and Immunology, 2004, Vol.193(4), pp.205-208
    Description: The underlying mechanisms leading to persistence of human cytomegalovirus (HCMV) in the immune privileged retina are not fully understood. This in vitro study was done to evaluate the influence of HCMV-infected retinal glial cells on epithelial barrier functions. Glial cells derived from human eyes were cultured and infected with the clinical HCMV isolate Hi91. Supernatants of mock (GS mock ) and Hi91 (GS Hi91 ) -infected glial cells were collected at 72 h post inoculation and used for incubation of CaCo-2 cells grown in transwell chambers. Transepithelial electrical resistance (TER) was analyzed as a measure of epithelial integrity. Virus-free GS Hi91 but not GS mock increased TER from 250 Ω/cm 2 to more than 1,000 Ω/cm 2 within 2 h. Increased TER values were measured up to 48 h ( n =3). No changes in TER were observed when conditioned supernatants from HCMV-infected human foreskin fibroblasts were used. No evidence of GS Hi91 -induced modification of β-catenin (zonula adherens) or occludin and ZO-1 (zonula occludens) was found. Our results suggest that HCMV-infected glial cells may support epithelial barrier functions by a yet unknown mechanism. Our findings may help to explain the ocular persistence of HCMV and the maintenance of ocular immune privilege early in infection.
    Keywords: Human cytomegalovirus ; Immune privilege ; Junction molecules ; Retinitis
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 7
    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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  • 8
    Language: English
    In: Neoplasia, July 2004, Vol.6(4), pp.323-331
    Description: Pathologic data indicate that human cytomegalovirus (HCMV) infection might be associated with the pathogenesis of several human malignancies. However, no definitive evidence of a causal link between HCMV infection and cancer dissemination has been established to date. This study describes the modulation of the invasive behavior of NCAM-expressing tumor cell lines by HCMV. Neuroblastoma (NB) cells, persistently infected with the HCMV strain AD169 (UKF-NB-4 and MHH-NB-11 ), were added to endothelial cell monolayers and adhesion and penetration kinetics were measured. The 140- and 180-kDa isoforms of the adhesion receptor NCAM were evaluated by flow cytometry, Western blot, and reverse transcriptionpolymerase chain reaction (RT-PCR). The relevance of NCAM for tumor cell binding was proven by treating NB with NCAM antisense oligonucleotides or NCAM transfection. HCMV infection profoundly increased the number of adherent and penetrated NB, compared to controls. Surface expression of NCAM was significantly lower on UKF-NB-4 and MHH-NB-11 , compared to mock-infected cells. Western-blot and RT-PCR demonstrated reduced protein and RNA levels of the 140- and 180-kDa isoform. An inverse correlation between NCAM expression and adhesion capacity of NB has been shown by antisense and transfection experiments. We conclude that HCMV infection leads to downregulation of NCAM receptors, which is associated with enhanced tumor cell invasiveness.
    Keywords: Hcmv ; Ncam ; Tumor Dissemination ; N-Myc ; P73 ; Medicine
    ISSN: 1476-5586
    ISSN: 15228002
    E-ISSN: 1476-5586
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  • 9
    Language: English
    In: Human Immunology, 1995, Vol.44(3), pp.136-144
    Description: Human cytomegalovirus (HCMV) infection has been associated with enhanced expression of HLA antigens on the endothelium and with cellular infiltrates within the graft following human organ transplantation. We investigated the interactions between human cytomegalovirus-infected cultured endothelial cells and cocultured syngeneic as well as allogeneic lymphocytes. Our objective was to find out whether cocultured lymphocytes elicit HCMV-mediated immune responses. In this report we focus on the modified expression of HLA antigens on the surface membrane of human umbilical vein endothelial cells (HUVECs). Endothelial expression of HLA class I and II antigens was measured by means of flow cytometry. Cocultures of HCMV-infected HUVECs with unprimed autologous PBLs led to virus-specific lymphocyte response, resulting in enhanced expression of HLA class I on HUVECs. This effect was only observed when lymphocytes were added to HUVECs during the very early phase after virus inoculation and was due to the stimulation of the CD8 + T-cell subpopulation. The modification of endothelial HLA expression was not observed in transwell cocultures, indicating the importance of cellular contact between endothelial cells and lymphocytes to elicit this effect. We conclude that HCMV-infected endothelial cells may induce virus-specific responses of unprimed syngeneic lymphocytes that lead to upregulated HLA class I expression on the endothelium. This pathway might be of important relevance for graft rejection crises after transplantation.
    Keywords: Medicine ; Biology
    ISSN: 0198-8859
    E-ISSN: 1879-1166
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  • 10
    Language: English
    In: Transplant Immunology, 1995, Vol.3(4), pp.313-320
    Description: Desferrioxamine (DFO), commonly used in therapy as a chelator of ferric ion in disorders of iron overload, is a potent inhibitor of human cytomegalovirus (HCMV) replication in cultured fibroblast cells. Moreover, DFO has immunomodulatory activity both in vitro and in vivo. We studied DFO effects on HCMV replication in cultured human endothelial cells and on the expression of several cell surface molecules, which mediate interactions of endothelial cells with other cell types in the immune system. The concentrations of DFO required for 50% reduction in the number of endothelial cells expressing HCMV late antigen, ranged for several HCMV strains from 5.2 to 8.8 mu M. DFO concentrations ranging from 5 to 40 mu M inhibited cellular DNA synthesis in a dose-dependent manner without any significant effects on the cell viability. DFO at 10 mu M concentration suppressed expression of intercellular adhesion molecule-1 (ICAM-1) and endothelial leucocyte adhesion molecule-1 (ELAM-1), while it had no significant effect on the expression of vascular cell adhesion molecule-1 (VCAM-1). Expression of HLA class I and class II was not influenced by DFO treatment. The results showed that DFO is both effective in inhibition of HCMV replication and expression of ICAM-1 and ELAM-1 in endothelial cells, a combination that warrants attention to its potential use to prevent HCMV-induced allograft rejection in transplant recipients.
    Keywords: Medicine ; Biology
    ISSN: 0966-3274
    E-ISSN: 1878-5492
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