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Hans Wilhelm Doerr

Publications and source records attributed to Hans Wilhelm Doerr.

At least 37 records · Page 2Linked to original sources
PubMed2005

High-dose hydrocortisone reduces expression of the pro-inflammatory chemokines CXCL8 and CXCL10 in SARS coronavirus-infected intestinal cells.

Clinical observations and our high-density oligonucleotide microarray results demonstrated increased expression of proinflammatory chemokines after SARS-CoV infection. Here, we investigated the influence of SARS-CoV infection on CXCL8 (interleukin 8) and CXCL10 (interferon-gamma-inducible protein 10) in human intestinal epithelial (Caco2) cells. RT-PCR and ELISA showed time-dependent up-regulation of both chemokines after SARS-CoV infection. Electric mobility shift assay revealed increased DNA binding activity of the cellular transcription factors activator protein 1 (AP-1) and nuclear factor (B (NF-kappaB) in SARS-CoV infected cells. High hydrocortisone concentrations (> or =50 microg/ml) completely prevented increased DNA binding activity of AP-1 and NF-kappaB and inhibited up-regulation of CXCL8 and CXCL10, but did not reduce chemokine expression to basal levels. Ribavirin that does not inhibit SARS-CoV replication in Vero cells inhibited SARS-CoV replication in Caco2 cells at therapeutical concentrations. Hydrocortisone neither influenced SARS-CoV titres alone nor in combination with ribavirin. Our results show that corticosteroids may be of limited benefit in the suppression of chemokine production by SARS-CoV-infected cells.

Animals↗
PubMed2004

Increased human cytomegalovirus replication in fibroblasts after treatment with therapeutical plasma concentrations of valproic acid.

Valproic acid (2-propylpentanoic acid, VPA), an effective inhibitor of histone deacetylases (HDAC) is used for the treatment of epilepsia. In this study, structure-activity relationships for the action of structurally modified VPA derivatives on human cytomegalovirus (HCMV) replication and HDAC inhibition were defined. Pretreatment of human foreskin fibroblasts with VPA (0.125-1mM) caused a concentration-dependent increase of HCMV immediate early and antigen late antigen expression. Structure-activity relationships of VPA derivatives for HCMV stimulation were compared to those for teratogenic action and those for HDAC inhibition. Side chain elongation and introduction of a triple bond in 4-position of the other chain caused teratogenicity, stimulated HCMV replication, and increased HDAC inhibition, as demonstrated by enhanced levels of acetylated histones. Teratogenic VPA derivatives with a branched chain in 3-position as well as a non-teratogenic anticonvulsive active VPA derivative did not stimulate HCMV or accumulation of acetylated histones. This demonstrates a strict correlation between inhibition of HDAC and increased HCMV replication.

Acetylation↗
PubMed2004

HIV protease inhibitor nelfinavir inhibits replication of SARS-associated coronavirus.

A novel coronavirus has been identified as an etiological agent of severe acute respiratory syndrome (SARS). To rapidly identify anti-SARS drugs available for clinical use, we screened a set of compounds that included antiviral drugs already in wide use. Here we report that the HIV-1 protease inhibitor, nelfinavir, strongly inhibited replication of the SARS coronavirus (SARS-CoV). Nelfinavir inhibited the cytopathic effect induced by SARS-CoV infection. Expression of viral antigens was much lower in infected cells treated with nelfinavir than in untreated infected cells. Quantitative RT-PCR analysis showed that nelfinavir could decrease the production of virions from Vero cells. Experiments with various timings of drug addition revealed that nelfinavir exerted its effect not at the entry step, but at the post-entry step of SARS-CoV infection. Our results suggest that nelfinavir should be examined clinically for the treatment of SARS and has potential as a good lead compound for designing anti-SARS drugs.

Animals↗
PubMed2004

Oncomodulatory signals by regulatory proteins encoded by human cytomegalovirus: a novel role for viral infection in tumor progression.

A high frequency of human cytomegalovirus (HCMV) genome and antigens in tumor samples of patients with different malignancies is now well documented, although the causative role for HCMV in the development of the neoplasias remains to be established. HCMV infection can modulate multiple cellular regulatory and signalling pathways in a manner similar to that of oncoproteins of small DNA tumor viruses such as human papilloma virus or adenoviruses. However, in contrast to these DNA tumor viruses, HCMV infection fails to transform susceptible normal human cells. There is now growing evidence that tumor cells with disrupted regulatory and signalling pathways enable HCMV to modulate their properties including stimulation of cell proliferation, survival, invasion, production of angiogenic factors, and immunogenic properties. In contrast to previously suggested "hit and run" transformation we suggest that persistence in tumor cells is essential for HCMV to fully express its oncomodulatory effects. These effects are observed particularly in persistent HCMV infection and are mediated mainly by activity of HCMV regulatory proteins. In persistently HCMV-infected tumor cell lines - a selection of novel, slowly growing virus variants with changes in coding sequences for virus regulatory proteins takes place. As a result, oncomodulatory effects of HCMV infection may lead to a shift to more malignant phenotype of tumor cells contributing to tumor progression.

Cell Cycle↗
PubMed2004

Retroviral vectors pseudotyped with severe acute respiratory syndrome coronavirus S protein.

The worldwide outbreak of severe acute respiratory syndrome (SARS) was shown to be associated with a novel coronavirus (CoV) now called SARS CoV. We report here the generation of SARS CoV S protein-pseudotyped murine leukemia virus (MLV) vector particles. The wild-type S protein pseudotyped MLV vectors, although at a low efficiency. Partial deletion of the cytoplasmic tail of S dramatically increased infectivity of pseudotypes, with titers only two- to threefold lower than those of pseudotypes generated in parallel with the vesicular stomatitis virus G protein. S-pseudotyped MLV particles were used to analyze viral tropism. MLV(SARS) pseudotypes and wild-type SARS CoV displayed similar cell types and tissue and host restrictions, indicating that the expression of a functional receptor is the major restraint in permissiveness to SARS CoV infection. Efficient gene transfer could be detected in Vero and CaCo2 cells, whereas the level of gene marking of 293T, HeLa, and HepG2 cells was only slightly above background levels. A cat cell line and a dog cell line were not susceptible. Interestingly, PK-15, a porcine kidney cell line, and primary porcine kidney cells were also highly permissive for SARS S pseudotypes and wild-type SARS CoV. This finding suggests that swine may be susceptible to SARS infection and may be a source for infection of humans. Taken together, these results indicate that MLV(SARS) pseudotypes are highly valuable for functional studies of viral tropism and entry and, in addition, can be a powerful tool for the development of therapeutic entry inhibitors without posing a biohazard to human beings.

Animals↗
PubMed2004

Role of interferons in the treatment of severe acute respiratory syndrome.

Severe acute respiratory syndrome (SARS) is caused by the SARS coronavirus (SCV). The disease appeared in the Guandong province of southern China in 2002. The epidemic affected > 8422 patients and caused 908 deaths in 29 countries on 5 continents. Several treatment modalities were tried with limited success to treat SARS and a variety of experimental drugs are under development. Type I interferons (IFNs-alpha/beta) were suggested as potential candidates to treat SARS. Several animal and human coronaviruses, including SCV, were shown to be sensitive to IFNs both in vitro and in vivo. A pilot clinical report showed effectiveness of IFN-alpha for the treatment of SARS patients. This review summarises antiviral activities of IFNs with special regard to SARS, and reviews the published clinical and experimental data describing the use of IFNs for SARS.

Animals↗
PubMed2004

SARS molecular detection external quality assurance.

Inactivated severe acute respiratory syndrome-associated coronavirus samples were used for an external quality assurance study within the World Health Organization SARS Reference and Verification Network and other reference institutions. Of 58 participants, 51 correctly detected virus in all samples > or =9,400 RNA copies per milliliter and none in negative samples. Commercial test kits significantly improved the outcome.

Humans↗
PubMed2004

Thrombin stimulates IL-6 and IL-8 expression in cytomegalovirus-infected human retinal pigment epithelial cells.

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-kappaB-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.

Cytomegalovirus↗
PubMed2003

Effects of S-acetylglutathione in cell and animal model of herpes simplex virus type 1 infection.

Intracellular glutathione (GSH) plays an important regulatory role in the host response to viral infections. Replenishment of intracellular GSH is a desirable yet challenging goal, since systemic GSH supplementation is rather inefficient due to a short half-life of GSH in blood plasma. Further, GSH is not taken up by cells directly, but needs to be broken down into amino acids and resynthesized to GSH intracellularly, this process often being impaired during viral infections. These obstacles may be overcome by a novel glutathione derivative S-acetylglutathione (S-GSH), which is more stable in plasma and taken up directly by cells with subsequent conversion to GSH. In the present study, in vitro effects of supplementation with S-GSH or GSH on intracellular GSH levels, cell survival and replication of human herpes simplex virus type 1 (HSV-1) were studied in human foreskin fibroblasts. In addition, in vivo effects of supplementation with S-GSH or GSH on HSV-1-induced mortality were studied in hr/hr mice. In cell culture, viral infection resulted in a significant decrease of intracellular GSH levels. S-GSH efficiently and dose-dependently (5 and 10 mM tested) restored intracellular GSH, and this replenishment was more efficient than with GSH supplementation. In mice, S-GSH, but not GSH, significantly decreased HSV-1-induced mortality ( P<0.05). The data suggest that S-GSH is a suitable antiviral agent against HSV-1 both in vitro and in vivo, indicating that this drug may be of benefit in the adjunctive therapy of HSV-1 infections.

Animals↗
PubMed2003

Thrombin induces Sp1-mediated antiviral effects in cytomegalovirus-infected human retinal pigment epithelial cells.

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.

Antiviral Agents↗
PubMed2003

Supernatants from human cytomegalovirus (HCMV)-infected retinal glial cells increase transepithelial electrical resistance in a cell culture model: evidence of HCMV immune escape in the eye?

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 Omega/cm(2) to more than 1,000 Omega/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 beta-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.

Blood-Retinal Barrier↗
PubMed2003

Identification of a novel coronavirus in patients with severe acute respiratory syndrome.

BACKGROUND: The severe acute respiratory syndrome (SARS) has recently been identified as a new clinical entity. SARS is thought to be caused by an unknown infectious agent. METHODS: Clinical specimens from patients with SARS were searched for unknown viruses with the use of cell cultures and molecular techniques. RESULTS: A novel coronavirus was identified in patients with SARS. The virus was isolated in cell culture, and a sequence 300 nucleotides in length was obtained by a polymerase-chain-reaction (PCR)-based random-amplification procedure. Genetic characterization indicated that the virus is only distantly related to known coronaviruses (identical in 50 to 60 percent of the nucleotide sequence). On the basis of the obtained sequence, conventional and real-time PCR assays for specific and sensitive detection of the novel virus were established. Virus was detected in a variety of clinical specimens from patients with SARS but not in controls. High concentrations of viral RNA of up to 100 million molecules per milliliter were found in sputum. Viral RNA was also detected at extremely low concentrations in plasma during the acute phase and in feces during the late convalescent phase. Infected patients showed seroconversion on the Vero cells in which the virus was isolated. CONCLUSIONS: The novel coronavirus might have a role in causing SARS.

Adult↗
PubMed2003

Potent oncolytic activity of multimutated herpes simplex virus G207 in combination with vincristine against human rhabdomyosarcoma.

Replication restricted oncolytic viruses such as multimutated herpes simplex virus type 1 (HSV-1) G207 represent a novel and attractive approach for cancer therapy, including pediatric solid tumors. Rhabdomyosarcoma is the most common soft-tissue sarcoma of childhood and is often diagnosed already as an advanced disseminated disease. Despite aggressive therapeutic approaches, the prognosis for patients with metastatic rhabdomyosarcoma remains grim. Therefore, there is a need for novel effective drugs with superior safety and efficacy profile. In this study, we showed marked in vitro activity of HSV-1 G207 against embryonal and alveolar rhabdomyosarcoma cells. All human embryonal (KF-RMS-1, RD, and CCA) and alveolar RMS (KFR, Rh28, Rh30, and Rh41) cell lines were highly sensitive to cytotoxic and replicative effects of G207 even at a multiplicity of infection of 0.01, except embryonal Rh1 rhabdomyosarcoma cells, which were efficiently killed only upon multiplicity of infection of 1.0. i.v. G207 treatment of xenotransplanted KFR and KF-RMS-1 tumors in mice led to significant tumor growth inhibition of both tumor entities, whereas intraneoplastic G207 treatment additionally resulted in complete tumor disappearance in 25% of animals. No difference has been found between alveolar and embryonal types of rhabdomyosarcoma. Combination treatment of both cell lines with G207 and vincristine led to strongly enhanced in vitro cytotoxicity without affecting infection efficiency and replication of G207 in KFR as well as in KF-RMS-1 cells. In vivo combination treatment using i.v. G207 and vincristine resulted in complete regression of alveolar rhabdomyosarcoma in five of eight animals and significant growth inhibition of embryonal rhabdomyosarcoma. Taking into consideration the proven safety of G207 in humans, we suggest that G207 alone and in combination with vincristine should be additionally evaluated as a potential agent against human rhabdomyosarcoma.

Animals↗
PubMed2003

Human cytomegalovirus retinitis: pathogenicity, immune evasion and persistence.

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-kappaB. 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.

Cytomegalovirus↗
PubMed2003

Mechanisms and enzymes involved in SARS coronavirus genome expression.

A novel coronavirus is the causative agent of the current epidemic of severe acute respiratory syndrome (SARS). Coronaviruses are exceptionally large RNA viruses and employ complex regulatory mechanisms to express their genomes. Here, we determined the sequence of SARS coronavirus (SARS-CoV), isolate Frankfurt 1, and characterized key RNA elements and protein functions involved in viral genome expression. Important regulatory mechanisms, such as the (discontinuous) synthesis of eight subgenomic mRNAs, ribosomal frameshifting and post-translational proteolytic processing, were addressed. Activities of three SARS coronavirus enzymes, the helicase and two cysteine proteinases, which are known to be critically involved in replication, transcription and/or post-translational polyprotein processing, were characterized. The availability of recombinant forms of key replicative enzymes of SARS coronavirus should pave the way for high-throughput screening approaches to identify candidate inhibitors in compound libraries.

Amino Acid Sequence↗