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  • 1
    Language: English
    In: Medical Microbiology and Immunology, 2011, Vol.200(1), pp.53-60
    Description: Influenza A virus infection of macrophages and virus-induced pro-inflammatory gene expression are regarded to contribute to severity of influenza A virus-caused diseases. Although some data are available on cytokine production by influenza A virus-infected macrophages, systematic comparisons of the virus types are currently considered to be of high relevance in humans (pandemic H1N1/2009, seasonal H1N1, seasonal H3N2, highly pathogenic avian influenza H5N1) on pro-inflammatory potential, and relevant underlying cellular signalling events are missing. Here, we show that the infection of human monocyte-derived macrophages with pandemic H1N1/2009 (A/HH/01/2009), seasonal H1N1/1999 (A/New Caledonia/20/99), seasonal H3N2/2004 (A/California/7/2004) or highly pathogenic H5N1/2004 (A/Thailand/1(Kan-1)/04) results in similar infection rates. However, the investigated H1N1 strains caused delayed and decreased apoptosis in comparison with H3N2/2004 or H5N1/2004. Moreover, human macrophage infection with H3N2/2004 or H5N1/2004 but not with H1N1 viruses was associated with pronounced pro-inflammatory cytokine production and activation of relevant mitogen-activated protein kinase pathways as indicated by phosphorylation of p38, JNK and ERK 1/2. These findings are in line with clinical observations indicating enhanced disease severity in H3N2- or H5N1-infected patients compared to individuals infected with pandemic H1N1/2009 or seasonal H1N1.
    Keywords: Influenza A ; MAPK ; Cytokines ; Seasonal influenza ; H5N1 ; Pandemic H1N1/2009
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 2
    Language: English
    In: Medical Microbiology and Immunology, 2010, Vol.199(2), pp.117-121
    Description: In April 2009, a new variant of influenza A virus, subtype H1N1v emerged in Mexico and spread all over the world producing the H1N1 pandemic in mankind after 1918–1920 and 1978/1979. Obviously there was no herd immunity against this new virus variant. Mainly young people, but less elderly were affected and presented severe and even lethal courses of disease. Since virus-specific antibodies are commonly regarded as markers of partial or complete immunoprotection, we performed antibody determinations in serum samples obtained from people before and after the pandemic has arrived in our region (Frankfurt/M., Germany). The assays were done by indirect immunofluorescence, by neutralization test, and by a haemagglutination inhibition test (HI), which was established in a practical modification for general and easy use. Among 145 individuals, of whom serum specimens had been drawn before the onset of pandemic, 19 revealed humoral immunity, i.e. titres of H1N1v neutralizing antibodies (at least 1:64). Eleven were older than 60 years, one belonged to the age group 40–59 years, three to the age group 20–39 years, and two to the age group 15–19 years. After the onset of pandemic in Frankfurt, serum specimens drawn from n  = 225 randomly selected patients of our local university hospital were investigated for antibodies against H1N1v by HI, which is generally recommended for routine check of immunity. Twenty-eight individuals revealed the protecting antibody titre of at least 1:40. The age distribution had moved to mean age groups. The results fit to the incidence of influenza A/H1N1(09) disease, as confirmed by RT–PCR in patients admitted to our hospital, peaking in the younger age groups up to 30 years (second affected group: 30–40 years). While commonly used solid-phase antibody tests (like immunofluorescence) are not suitable to diagnose passed H1N1(09) infection and acquired immunity, this can be easily done by HI. Expecting the next waves of influenza A/H1N1v infections, HI testing may avoid vaccinations under special risk of severe or hidden adverse reactions.
    Keywords: H1N1 pandemic ; Seroprevalence ; Immunity
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 3
    Language: English
    In: Medical Microbiology and Immunology, 2010, Vol.199(4), pp.291-297
    Description: Hypercytokinaemia is thought to contribute to highly pathogenic H5N1 influenza A virus disease. Glycyrrhizin is known to exert immunomodulatory and anti-inflammatory effects and therefore a candidate drug for the control of H5N1-induced pro-inflammatory gene expression. Here, the effects of an approved parenteral glycyrrhizin preparation were investigated on H5N1 virus replication, H5N1-induced pro-inflammatory responses, and H5N1-induced apoptosis in human monocyte-derived macrophages. Glycyrrhizin 100 μg/ml, a therapeutically achievable concentration, impaired H5N1-induced production of CXCL10, interleukin 6, and CCL5 and inhibited H5N1-induced apoptosis but did not interfere with H5N1 replication. Global inhibition of immune responses may result in the loss of control of virus replication by cytotoxic immune cells including natural killer cells and cytotoxic CD8 + T-lymphocytes. Notably, glycyrrhizin concentrations that inhibited H5N1-induced pro-inflammatory gene expression did not affect cytolytic activity of natural killer cells. Since H5N1-induced hypercytokinaemia is considered to play an important role within H5N1 pathogenesis, glycyrrhizin may complement the arsenal of potential drugs for the treatment of H5N1 disease.
    Keywords: Glycyrrhizin ; H5N1 ; Cytokines ; Monocyte-derived macrophages
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 4
    Language: English
    In: Medical Microbiology and Immunology, 2010, Vol.199(2), pp.93-101
    Description: Tumor resistance to lysis by resting natural killer (NK) cells may be overcome by priming of NK cells with cytokines or by binding of NK activating receptors to ligands expressed on target cells. In this study, major histocompatibility complex class I (MHC-I)-negative LNCaP and MHC-I-positive DU145 cells were infected with genetically modified influenza A virus lacking the non-structural gene 1 (∆NS1 IAV). The cells were used to investigate the influence of ∆NS1 IAV infection on NK cell lysis of tumor cells as well as to prime NK cells for lysis of LNCaP and DU145 cells. While LNCaP cells infected with ΔNS1 IAV showed enhanced lysis when compared with mock-infected cells (93% ± 1.47 vs. 52% ± 0.74), both mock-infected and ΔNS1 IAV-infected DU145 cells were resistant to NK cell lysis. Moreover, NK cells primed with ΔNS1 IAV-infected LNCaP/DU145 cells effectively lysed resistant DU145 and sensitive LNCaP cells to a greater extent than NK cells primed with mock-infected LNCaP/DU145 or non-primed NK cells. Also, NK cell priming with ΔNS1 IAV-infected tumor cells enhanced extracellular signal-regulated kinase phosphorylation and increased granule release in NK cells. The increased granule release was specifically mediated by NKp46, which eventually potentiated NK cells primed with ΔNS1 IAV-infected tumor cells to overcome the inhibitory effects posed by MHC-I expression on DU145 cells. These findings show that in addition to direct lytic activity of NK cells, ΔNS1 IAV may influence anti-tumoral responses by priming NK cells.
    Keywords: Cytotoxicity ; NK cell priming ; Major histocompatibility complex class I ; Degranulation ; Oncolytic influenza A virus
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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  • 5
    Language: English
    In: Medical Microbiology and Immunology, 2009, Vol.198(4), pp.257-262
    Description: A coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase released from injured target cells was used to evaluate the cytotoxicity of antigen-specific HLA class I-restricted CTLs. In contrast to established methods, CLM does not require the pretreatment of target cells with radioactive or toxic labeling substances. CTLs from healthy HLA-A2 positive donors were stimulated by autologous dendritic cells (DCs) pulsed with HLA-A2 restricted HCMV-pp65 nonamer peptides. HLA-A2 positive T2 cells or autologous monocytes pulsed with HCMV-pp65 nonamer peptide served as target cells. Lysis was detected only in HCMV-pp65-pulsed target cells incubated with CTLs from seropositive donors stimulated by HCMV-pp65-pulsed DCs. After 3 days, stimulation 38% of T2 cells and 17% of monocytes were lysed at an effector to target ratio of 8:1. In conclusion, CLM represents a highly sensitive, fast, material-saving and non-toxic/non-radioactive method for the measurement of antigen-specific CTL cytotoxic activity.
    Keywords: Cytotoxic T lymphocytes ; HLA-A2-restricted peptide ; Human cytomegalovirus ; Cytotoxicity ; Coupled luminescent method ; Dendritic cells
    ISSN: 0300-8584
    E-ISSN: 1432-1831
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