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Berlin Brandenburg

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  • Antiviral Agents
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  • 1
    Language: English
    In: Medical Microbiology and Immunology, 2007, Vol.196(4), pp.203-212
    Description: Among emerging and re-emerging infectious diseases, influenza constitutes one of the major threats to mankind. In this review series epidemiologic, virologic and pathologic concerns raised by infections of humans with avian influenza virus A/H5N1 as well as treatment options are discussed. The third part discusses therapeutic options. Neuraminidase (NA) inhibitors are the most promising agents despite uncertainty about efficacy. Dosage increase, prolonged treatment or combination therapies may increase treatment efficacy and/or inhibit resistance formation. Immune system dysregulation contributes to H5N1 disease. Although current evidence does not support the use of anti-inflammatory drugs beneficial effects cannot be excluded at later disease stages.
    Keywords: Antiviral Agents ; Avian Influenza;
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 2
    Language: English
    In: PLoS ONE, 2011, Vol.6(5), p.e19705
    Description: Glycyrrhizin is known to exert antiviral and anti-inflammatory effects. Here, the effects of an approved parenteral glycyrrhizin preparation (Stronger Neo-Minophafen C) were investigated on highly pathogenic influenza A H5N1 virus replication, H5N1-induced apoptosis, and H5N1-induced pro-inflammatory responses in lung epithelial (A549) cells. Therapeutic glycyrrhizin concentrations substantially inhibited H5N1-induced expression of the pro-inflammatory molecules CXCL10, interleukin 6, CCL2, and CCL5 (effective glycyrrhizin concentrations 25 to 50 µg/ml) but interfered with H5N1 replication and H5N1-induced apoptosis to a lesser extent (effective glycyrrhizin concentrations 100 µg/ml or higher). Glycyrrhizin also diminished monocyte migration towards supernatants of H5N1-infected A549 cells. The mechanism by which glycyrrhizin interferes with H5N1 replication and H5N1-induced pro-inflammatory gene expression includes inhibition of H5N1-induced formation of reactive oxygen species and (in turn) reduced activation of NFκB, JNK, and p38, redox-sensitive signalling events known to be relevant for influenza A virus replication. Therefore, glycyrrhizin may complement the arsenal of potential drugs for the treatment of H5N1 disease.
    Keywords: Research Article ; Medicine ; Infectious Diseases ; Pharmacology
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: Cellular and Molecular Life Sciences, 2011, Vol.68(6), pp.1079-1090
    Description: Human cytomegalovirus (HCMV) is a major pathogen in immunocompromised individuals. Here, non-toxic concentrations of the anti-cancer kinase inhibitor sorafenib were shown to inhibit replication of different HCMV strains (including a ganciclovir-resistant strain) in different cell types. In contrast to established anti-HCMV drugs, sorafenib inhibited HCMV major immediate early promoter activity and HCMV immediate early antigen (IEA) expression. Sorafenib is known to inhibit Raf. Comparison of sorafenib with the MEK inhibitor U0126 suggested that sorafenib inhibits HCMV IEA expression through inhibition of Raf but independently of signaling through the Raf downstream kinase MEK 1/2. In concordance, siRNA-mediated depletion of Raf but not of MEK-reduced IEA expression. In conclusion, sorafenib diminished HCMV replication in clinically relevant concentrations and inhibited HCMV IEA expression, a pathophysiologically relevant event that is not affected by established anti-HCMV drugs. Moreover, we demonstrated for the first time that Raf activation is involved in HCMV IEA expression.
    Keywords: Human cytomegalovirus ; Sorafenib ; Kinase inhibitor ; Raf ; Immediate early antigen ; Cancer chemotherapy ; Oncomodulation ; Antiviral therapy
    ISSN: 1420-682X
    E-ISSN: 1420-9071
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 23 October 2018, Vol.115(43), pp.E10022-E10031
    Description: SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that depletes cellular dNTPs in noncycling cells to promote genome stability and to inhibit retroviral and herpes viral replication. In addition to being substrates, cellular nucleotides also allosterically regulate SAMHD1 activity. Recently, it was shown that high expression levels of SAMHD1 are also correlated with significantly worse patient responses to nucleotide analog drugs important for treating a variety of cancers, including acute myeloid leukemia (AML). In this study, we used biochemical, structural, and cellular methods to examine the interactions of various cancer drugs with SAMHD1. We found that both the catalytic and the allosteric sites of SAMHD1 are sensitive to sugar modifications of the nucleotide analogs, with the allosteric site being significantly more restrictive. We crystallized cladribine-TP, clofarabine-TP, fludarabine-TP, vidarabine-TP, cytarabine-TP, and gemcitabine-TP in the catalytic pocket of SAMHD1. We found that all of these drugs are substrates of SAMHD1 and that the efficacy of most of these drugs is affected by SAMHD1 activity. Of the nucleotide analogs tested, only cladribine-TP with a deoxyribose sugar efficiently induced the catalytically active SAMHD1 tetramer. Together, these results establish a detailed framework for understanding the substrate specificity and allosteric activation of SAMHD1 with regard to nucleotide analogs, which can be used to improve current cancer and antiviral therapies.
    Keywords: Samhd1 ; Allosteric Regulation ; Dntpase ; Nucleotide Analog Drugs ; Substrate Selection ; Allosteric Site -- Drug Effects ; Catalytic Domain -- Drug Effects ; Drug Interactions -- Physiology ; Leukemia, Myeloid, Acute -- Metabolism ; SAM Domain and HD Domain-Containing Protein 1 -- Metabolism
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 5
    Language: English
    In: Medical Microbiology and Immunology, 2011, Vol.200(3), pp.193-202
    Description: The treatment of varicella-zoster virus (VZV) reactivation is based on nucleoside analogues acyclovir (ACV) and bromevinyldeoxyuridine (BVdU) and a phosphonic acid derivative (PFA). Drug-resistant mutants of 3 wild-type (WT) VZV strains were obtained by exposure of human retinal pigment epithelial (hRPE) cells inoculated with cell-free WT virus at increasing concentrations of ACV, BVdU, and PFA. In addition to single-drug resistance, a cross-resistance of isolates vs. ACV was observed for PFA-resistant strains. Single-nucleotide (nt) exchanges resulting in amino acid (aa) substitutions were observed within the DNA polymerase (ORF 28) and/or thymidine kinase (ORF 36) of 3 of 3 ACV-, 2 of 3 BVdU-, and 3 of 3 PFA-resistant strains. Interestingly, aa substitutions were also observed within the immediate-early regulatory protein and major transactivator IE 62 (ORF 62), and the envelope glycoprotein (g) I (ORF 67) of the BVdU-resistant mutant of strain PP. No aa substitutions were observed in the protein sequences of gene products encoded by ORF 5 (gK, a glycoprotein arranging exocytosis of viral-loaded vacuoles), ORF 14 (gC), ORF 31 (gB), ORF 37 (gH), ORF 47 (protein kinase, involved in major phosphorylating processes), ORF 60 (gL, important for syncytia forming of infected cells in combination with gH), ORF 63 (major transactivator, part of the tegument), and ORF 68 (gE, triggers fusion of viral loaded vacuoles with cell membranes by heterodimerizing with gI). Phenotypic analysis revealed a slow-growth phenotype and a formation of smaller plaques of resistant mutants. Future studies should prove the presence of those resistant mutants in herpes zoster patients and the potential consequences of their putative reduced fitness on the success of therapeutical interventions.
    Keywords: VZV ; Acyclovir ; Bromevinyldeoxyuridine ; Phosphonoformiat ; Brivudine ; IE62 ; Glycoprotein ; Resistance
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 6
    Language: English
    In: Phytomedicine, 2011, Vol.18(5), pp.384-386
    Description: The extract EPs 7630 is an approved drug for the treatment of acute bronchitis in Germany. The postulated mechanisms underlying beneficial effects of EPs 7630 in bronchitis patients include immunomodulatory and cytoprotective effects, inhibition of interaction between bacteria and host cells, and increase of cilliary beat frequency on respiratory cells. Here, we investigated the influence of EPs 7630 on replication of a panel of respiratory viruses. Determination of virus-induced cytopathogenic effects and virus titres revealed that EPs 7630 at concentrations up to 100 μg/ml interfered with replication of seasonal influenza A virus strains (H1N1, H3N2), respiratory syncytial virus, human coronavirus, parainfluenza virus, and coxsackie virus but did not affect replication of highly pathogenic avian influenza A virus (H5N1), adenovirus, or rhinovirus. Therefore, antiviral effects may contribute to the beneficial effects exerted by EPs 7630 in acute bronchitis patients.
    Keywords: Pelargonium Sidoides ; Respiratory Viruses ; Acute Bronchitis ; Medicine ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0944-7113
    E-ISSN: 1618-095X
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  • 7
    In: BMC Research Notes, 2014, Vol.7, p.384-384
    Description: Background Different flavonoids are known to interfere with influenza A virus replication. Recently, we showed that the structurally similar flavonoids baicalein and biochanin A inhibit highly pathogenic avian H5N1 influenza A virus replication by different mechanisms in A549 lung cells. Here, we investigated the effects of both compounds on H5N1-induced reactive oxygen species (ROS) formation and the role of ROS formation during H5N1 replication. Findings Baicalein and biochanin A enhanced H5N1-induced ROS formation in A549 cells and primary human monocyte-derived macrophages. Suppression of ROS formation induced by baicalein and biochanin A using the antioxidant N-acetyl-L-cysteine strongly increased the anti-H5N1 activity of both compounds in A549 cells but not in macrophages. Conclusions These findings emphasise that flavonoids induce complex pharmacological actions some of which may interfere with H5N1 replication while others may support H5N1 replication. A more detailed understanding of these actions and the underlying structure-activity relationships is needed to design agents with optimised anti-H5N1 activity.
    Keywords: Short Report ; H5n1 ; Biochanin A ; Baicalein ; Antiviral ; Reactive Oxygen Species ; N-Acetyl-L-Cysteine
    E-ISSN: 1756-0500
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  • 8
    Language: English
    In: Antiviral Research, January 2013, Vol.97(1), pp.41-48
    Description: ► 22 Flavonoids were examined for activity against H5N1 influenza A viruses. ► Biochanin A and baicalein exerted the highest potency. ► Biochanin A and baicalein interfered with H5N1 replication. ► Biochanin A and baicalein interfered with virus-induced cytokine expression. ► Biochanin A and baicalein differ in their molecular antiviral mechanisms. From a panel of 22 flavonoids, we identified six compounds (apigenin, baicalein, biochanin A, kaempferol, luteolin, naringenin) that inhibited influenza A nucleoprotein production in human lung epithelial (A549) cells infected with the highly pathogenic avian influenza H5N1 virus strain A/Thailand/Kan-1/04 in non-toxic concentrations. Baicalein ( : 18.79 ± 1.17 μM, selectivity index 5.82) and biochanin A ( 8.92 ± 1.87 μM, selectivity index 5.60) were selected for further experiments. Both compounds reduced H5N1 infectious titres (baicalein 40 μM: 29-fold reduction, biochanin A 40 μM: 55-fold reduction after infection at MOI 0.01), virus-induced caspase 3 cleavage, nuclear export of viral RNP complexes, and enhanced the effects of the neuraminidase inhibitor zanamivir. Biochanin A and baicalein also inhibited the replication of the H5N1 strain A/Vietnam/1203/04. Time of addition experiments indicated that both compounds interfere with H5N1 replication after the adsorption period. Further mechanistic investigations revealed clear differences between these two flavonoids. Only baicalein interfered with the viral neuraminidase activity (39 ± 7% inhibition at 100 μM, the maximum concentration tested). In contrast to baicalein, biochanin A affected cellular signalling pathways resulting in reduced virus-induced activation of AKT, ERK 1/2, and NF-kB. Moreover, biochanin A inhibited the virus-induced production of IL-6, IL-8, and IP-10 while baicalein inhibited IL-6 and IL-8 production without affecting IP-10 levels. In primary human monocyte-derived macrophages, only baicalein but not biochanin A impaired H5N1 virus replication. Both flavonoids interfered with the H5N1-induced production of IL-6, IP-10, and TNF-α but not of IL-8 in macrophages. These findings indicate that closely related flavonoids can exert anti-H5N1 effects by different molecular mechanisms.
    Keywords: H5n1 ; Biochanin A ; Baicalein ; Antiviral ; Anti-Inflammatory ; Flavonoid ; Medicine ; Biology
    ISSN: 0166-3542
    E-ISSN: 1872-9096
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  • 9
    Language: English
    In: Biochemical Pharmacology, 15 January 2010, Vol.79(2), pp.188-197
    Description: Ribavirin, a broad-spectrum anti-viral drug, exhibits immunomodulatory activities. To study direct effects of ribavirin on natural killer (NK) cell effector functions and signaling, resting NK cells and interleukin (IL)-15-activated NK cells were treated for 5 days with therapeutic ribavirin concentrations ranging from 5 μg/ml to 20 μg/ml. Both resting and IL-15-activated NK cells that were not treated with ribavirin were used as control. Cytotoxicity assays, flow cytometry, enzyme linked immunosorbent assays, and Western blot experiments were performed to elucidate ribavirin effect on NK cells. Results showed that ribavirin (not toxic at concentrations tested; IC 〉 80 μg/ml) had no influence on lysis of target cells by freshly isolated NK cells. Conversely, ribavirin dose-dependently inhibited lysis of target cells by up to 66% and impaired interferon gamma production when IL-15-activated NK cells were used. IL-15-induced increased expression and hence function of NK cell activating receptors including NKp30, NKp44, NKp46 and NKG2D were selectively down-regulated and impaired. These inhibitory effects were associated with the down-regulation of IL-15 receptor beta and gamma expression. Accordingly, downstream events involved in NK cell signaling via IL-15 receptors including the activation of Janus kinase (Jak)-1, signal transducer and activator of transcription STAT-1, STAT-3, and STAT-5 as well as pathways responsible for NK cell degranulation including extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal kinase (JNK) were impaired. These results reveal a novel mechanism by which ribavirin exerts its immunomodulatory activities.
    Keywords: Nk Cell Activating Receptors ; Nk Cell Signaling ; Nk Cell Degranulation ; Perforin and Granzyme B Release ; Il-15 Receptors ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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  • 10
    Language: English
    In: Biochemical Pharmacology, 01 February 2010, Vol.79(3), pp.413-420
    Description: The antioxidant N-acetyl- -cysteine (NAC) had been shown to inhibit replication of seasonal human influenza A viruses. Here, the effects of NAC on virus replication, virus-induced pro-inflammatory responses and virus-induced apoptosis were investigated in H5N1-infected lung epithelial (A549) cells. NAC at concentrations ranging from 5 to 15 mM reduced H5N1-induced cytopathogenic effects (CPEs), virus-induced apoptosis and infectious viral yields 24 h post-infection. NAC also decreased the production of pro-inflammatory molecules (CXCL8, CXCL10, CCL5 and interleukin-6 (IL-6)) in H5N1-infected A549 cells and reduced monocyte migration towards supernatants of H5N1-infected A549 cells. The antiviral and anti-inflammatory mechanisms of NAC included inhibition of activation of oxidant sensitive pathways including transcription factor NF-κB and mitogen activated protein kinase p38. Pharmacological inhibitors of NF-κB (BAY 11-7085) or p38 (SB203580) exerted similar effects like those determined for NAC in H5N1-infected cells. The combination of BAY 11-7085 and SB203580 resulted in increased inhibitory effects on virus replication and production of pro-inflammatory molecules relative to either single treatment. NAC inhibits H5N1 replication and H5N1-induced production of pro-inflammatory molecules. Therefore, antioxidants like NAC represent a potential additional treatment option that could be considered in the case of an influenza A virus pandemic.
    Keywords: Ros ; NAC ; Cytokines ; H5n1 ; Apoptosis ; Pharmacy, Therapeutics, & Pharmacology ; Chemistry
    ISSN: 0006-2952
    E-ISSN: 1873-2968
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