Biomedical subjects

Thomas Giese

Publications and source records attributed to Thomas Giese.

67 records · Page 4Linked to original sources

PubMed2004

Differential effects on innate versus adaptive immune responses by WF10.

Oxidative compounds that are physiologically generated in vivo can induce natural defense mechanisms to enhance the elimination of pathogens and to limit inflammatory tissue damage in the course of inflammation. Here, we have investigated WF10, a chlorite-based non-toxic compound for its functional activities on human PBMC in vitro. WF10 exerts potent immune-modulatory effects through generating endogenous oxidative compounds such as taurine chloramine. Proliferation and IL-2 production of anti-CD3 stimulated PBMC were inhibited by WF10, as was the nuclear translocation of the transcription factor NFATc. In PBMC and monocytes, however, WF10 induced pro-inflammatory cytokines like IL-1beta, IL-8, and TNF-alpha. In the monocytic cell line THP-1, the activation of the transcription factors AP-1 and NFkappaB by WF10 was demonstrated. Inhibition of NFAT regulated genes in activated lymphocytes in concert with the induction of several myeloid cell associated pro-inflammatory genes in monocytes represents a novel mechanism of immune modulation.

Chlorine↗

PubMed2004

Analysis of NFAT-regulated gene expression in vivo: a novel perspective for optimal individualized doses of calcineurin inhibitors.

BACKGROUND: With the introduction of cyclosporine A (CsA) long-term allograft function has been significantly improved. Problems regarding limited therapeutic margins and CsA toxicity remain unsolved. Up to now there are no reliable, practical markers to measure the biological activity of CsA in vivo. METHODS: Expression of nuclear factor of activated T lymphocytes (NFAT)-regulated genes in PMA/ionomycin-stimulated peripheral blood from stable renal-transplant (n = 25) recipients under CsA therapy were measured by quantitative real-time RT-PCR before and 2 h after drug intake. The relative expression of three NFAT-regulated genes was scored, averaged and presented as the multi-gene expression score ranging from 0 to 12 points. Gene expression data and CsA plasma levels were correlated. RESULTS: A reliable and precise method to measure functional consequences of calcineurin inhibition in the individual patient was established. The individual decline in NFAT-regulated gene expression and the total drug exposure were in close relation (rho = 0.602). CONCLUSION: Quantitative measurement of NFAT-regulated gene expression in CsA-treated patients represents a potent new approach to assess the biological effectiveness of CsA therapy and has the potential to enable individualized immunosuppressive regimens.

Adult↗

PubMed2004

Severe anaphylactic reaction to infliximab: successful treatment with adalimumab - report of a case.

Treatment with the anti-tumour necrosis factor alpha chimeric monoclonal antibody infliximab is highly effective in the treatment of refractory and fistulising Crohn's disease. Infliximab has been tolerated well, with minimal and short-lived adverse effects. The likelihood of severe reactions to infliximab, such as acute and delayed hypersensitivity infusion reactions, is small; nevertheless, if they do occur, they are life-threatening. We report a case of an anaphylaxis-like reaction in a 22-year-old female with long-standing Crohn's disease. The patient was treated successfully with adalimumab, a fully human anti-tumour necrosis factor alpha monoclonal antibody. Follow-up demonstrated mucosal healing and normalisation of elevated pro-inflammatory cytokine transcripts.

Adalimumab↗

PubMed2004

Differential antiviral response of endothelial cells after infection with pathogenic and nonpathogenic hantaviruses.

Hantaviruses represent important human pathogens and can induce hemorrhagic fever with renal syndrome (HFRS), which is characterized by endothelial dysfunction. Both pathogenic and nonpathogenic hantaviruses replicate without causing any apparent cytopathic effect, suggesting that immunopathological mechanisms play an important role in pathogenesis. We compared the antiviral responses triggered by Hantaan virus (HTNV), a pathogenic hantavirus associated with HFRS, and Tula virus (TULV), a rather nonpathogenic hantavirus, in human umbilical vein endothelial cells (HUVECs). Both HTNV- and TULV-infected cells showed increased levels of molecules involved in antigen presentation. However, TULV-infected HUVECs upregulated HLA class I molecules more rapidly. Interestingly, HTNV clearly induced the production of beta interferon (IFN-beta), whereas expression of this cytokine was barely detectable in the supernatant or in extracts from TULV-infected HUVECs. Nevertheless, the upregulation of HLA class I on both TULV- and HTNV-infected cells could be blocked by neutralizing anti-IFN-beta antibodies. Most strikingly, the antiviral MxA protein, which interferes with hantavirus replication, was already induced 16 h after infection with TULV. In contrast, HTNV-infected HUVECs showed no expression of MxA until 48 h postinfection. In accordance with the kinetics of MxA expression, TULV replicated only inefficiently in HUVECs, whereas HTNV-infected cells produced high titers of virus particles that decreased after 48 h postinfection. Both hantavirus species, however, could replicate equally well in Vero E6 cells, which lack an IFN-induced MxA response. Thus, delayed induction of antiviral MxA in endothelial cells after infection with HTNV could allow viral dissemination and contribute to the pathogenesis leading to HFRS.

Animals↗

PubMed2003

Plasmacytoid dendritic cells, antigen, and CpG-C license human B cells for plasma cell differentiation and immunoglobulin production in the absence of T-cell help.

It has been reported that interferon alpha (IFN-alpha) enhances humoral immunity and that dendritic cells of the myeloid lineage promote B-cell differentiation. Here we studied whether the plasmacytoid dendritic cell (PDC), a subset of dendritic cells specialized for the production of IFN-alpha, is involved in regulating B-cell differentiation and immunoglobulin production. The recently identified class of CpG oligonucleotides (CpG-C) was used to activate both B cells and PDCs via Toll-like receptor 9 (TLR9). The presence of PDCs synergistically enhanced CD86 expression, cytokine production (interleukin 6 [IL-6], tumor necrosis factor alpha, and IL-10) and plasma cell differentiation of isolated human peripheral blood B cells stimulated through CpG-C and B-cell antigen receptor (BCR) ligation. This stimulation protocol was sufficient to drive purified naive B cells into IgM-producing plasma cells and to trigger IgG synthesis in memory B cells. PDCs contributed to B-cell activation via IFN-alpha secretion. Up-regulation of TLR9 on B cells was not involved. These results demonstrate that CpG-stimulated PDCs induce plasma cell differentiation in naive and memory B cells in the absence of T-cell help, providing an explanation for the excellent activity of CpG oligonucleotides as a humoral vaccine adjuvant.

Antigens↗

PubMed2003

Cytokine/chemokine transcript profiles reflect mucosal inflammation in Crohn's disease.

BACKGROUND AND AIMS: Immunoregulatory properties of cytokines may contribute to pathological immune reactions in inflammatory bowel disease. There is an urgent need for a simple and dependable means for quantitating inflammatory activity in mucosal biopsies and assessing relapse risk particularly in patients with active Crohn's disease (CD). PATIENTS AND METHODS: Cytokine and chemokine transcripts were quantified using real-time PCR in mucosal biopsy specimens from 70 patients with active inflammatory bowel disease (CD, n=45; ulcerative colitis n=25) and 16 patients with specific colitis (ischemic colitis, infectious colitis). Controls were 12 patients with noninflammatory conditions. CD patients with steroid-induced remission (n=20) were followed for up to 12 months. RESULTS: Compared to not-inflamed mucosa the vast majority of active CD tissue samples expressed significantly elevated transcript levels of IL-1beta, IL-8, IL-23, MRP-14, MIP2alpha, and MMP-1. Moreover, increased cytokine transcript levels were detected in both active ulcerative colitis and specific colitis. Importantly, TNF-alpha, IFN-gamma, CD40L, and IL-23 transcripts increased in active CD only. Transcript levels (MRP-14, IL-8, MMP-1, MIP2alpha) were correlated with clinical disease activity (CDAI) and endoscopic scoring indices. Medical treatment induced stable remission in 14 of 20 patients which was paralleled by a reduction in increased transcript levels. All six patients without normalization of MIP2alpha, MRP-14, TNF-alpha, and IL-1beta transcripts developed an early relapse (n=5) or chronic activity (n=1) during follow-up. CONCLUSION: Elevated proinflammatory cytokine transcripts in active CD may underlie disease reactivation and chronicity. Real-time PCR quantification is a simple and objective method for grading inflammation of intestinal mucosa and may be useful in identifying patients who would benefit from anti-inflammatory remission maintenance.

Adolescent↗

PubMed2003

Identification and functional analysis of tumor-infiltrating plasmacytoid dendritic cells in head and neck cancer.

The antitumor activity of IFN-alpha is well established. However, the role of the plasmacytoid dendritic cell (PDC), the major producer of IFN-alpha upon viral infection, in tumor biology is unknown. We sought to study the presence and function of PDC in a human solid tumor. Here, we demonstrate that PDCs infiltrate tumor tissue of patients with head and neck squamous cell carcinoma (HNSCC). Functional activity of PDC was examined by using CpG motif containing oligonucleotides, a defined microbial stimulus for PDCs (recognized via toll-like receptor 9). We found that HNSCC diminished the ability of PDC to produce IFN-alpha in response to CpG motif containing oligonucleotide. Tumor-induced down-regulation of toll-like receptor 9 was identified as one mechanism likely contributing to impaired PDC function within the tumor environment. In tumor-draining lymph nodes, suppression of CpG-induced IFN-alpha production was less pronounced than in single-cell suspensions of primary tumor tissue. In these lymph nodes, CpG-induced IFN-alpha production was associated with increased levels of interferon-induced protein 10 and IFN-gamma and activation of CD4 and CD8 T cells. These results show for the first time the presence of PDCs in human solid tumor tissue and that tumors suppress the capacity of PDCs to produce IFN-alpha. PDCs, which in the absence of appropriate stimulation are reported to promote regulatory CD8 T cells, may contribute to an impaired T-cell-mediated immune response in HNSCC.

Adolescent↗

PubMed2003

Activation with CpG-A and CpG-B oligonucleotides reveals two distinct regulatory pathways of type I IFN synthesis in human plasmacytoid dendritic cells.

Two different CpG oligonucleotides (ODN) were used to study the regulation of type I IFN in human plasmacytoid dendritic cells (PDC): ODN 2216, a CpG-A ODN, known to induce high amounts of IFN-alpha in PDC, and ODN 2006, a CpG-B ODN, which is potent at stimulating B cells. CpG-A ODN showed higher and prolonged kinetics of type I IFN production compared with that of CpG-B ODN. In contrast, CpG-B ODN was more active than CpG-A ODN in stimulating IL-8 production and increasing costimulatory and Ag-presenting molecules, suggesting that CpG-A and CpG-B trigger distinct regulatory pathways in PDC. Indeed, CpG-A ODN, but not CpG-B ODN, activated the type I IFNR-mediated autocrine feedback loop. PDC were found to express high constitutive levels of IFN regulatory factor (IRF)7. IRF7 and STAT1, but not IRF3, were equally up-regulated by both CpG-A and CpG-B. CD40 ligand synergistically increased CpG-B-induced IFN-alpha independent of the IFNR but did not affect CpG-B-induced IFN-beta. In conclusion, our studies provide evidence for the existence of two distinct regulatory pathways of type I IFN synthesis in human PDC, one dependent on and one independent of the IFNR-mediated feedback loop. The alternate use of these pathways is based on the type of stimulus rather than the quantity of IFN-alphabeta available to trigger the IFNR. Constitutive expression of IRF7 and the ability to produce considerable amounts of IFN-alpha independent of the IFNR seem to represent characteristic features of PDC.

Adjuvants, Immunologic↗

PubMed2003

CpG-A oligonucleotides induce a monocyte-derived dendritic cell-like phenotype that preferentially activates CD8 T cells.

Human B cells and plasmacytoid dendritic cells recognize CpG motifs within microbial DNA via Toll-like receptor 9. Two functionally distinct types of CpG motif containing oligonucleotides (CpG ODN) have been described, CpG-A and CpG-B. In contrast to CpG-B, CpG-A induces high amounts of type I IFN (IFN-alpha and IFN-beta) in plasmacytoid dendritic cells. In the present study, we examined the effects of CpG-A on human primary monocytes. In PBMC stimulated with CpG-A and GM-CSF, monocytes showed excellent survival, increased in size and granularity, and within 3 days developed a dendritic cell-like phenotype that was characterized by down-regulation of CD14, partial up-regulation of CCR7, and an increased surface expression of costimulatory and Ag-presenting molecules. This effect could be inhibited by a combination of blocking Abs to type I IFN, and no such CpG-A-induced changes were observed in purified monocytes. Although IL-12 production by this dendritic cell-like phenotype required additional stimulation with CD40 ligand, this cell type spontaneously up-regulated IL-15 expression. Consistent with the known effect of IL-15 on effector and memory CD8 T cells, the frequency of CCR7(-)/CD45RA(-) CD8 T cells was selectively increased in allogeneic T cell assays. Furthermore, this dendritic cell type was more potent to support both the generation and the IFN-gamma production of autologous influenza matrix peptide-specific memory CD8 T cells as compared with dendritic cells generated in the presence of GM-CSF and IL-4. In conclusion, monocytes exposed to the cytokine milieu provided by CpG-A rapidly develop a dendritic cell-like phenotype that is well equipped to support CD8 T cell responses.

Adjuvants, Immunologic↗

PubMed2003

Functional characterization of pro-biotic pharmaceuticals by quantitative analysis of gene expression.

Functional characterization and quality control of complex biological pharmaceuticals are currently difficult to achieve. Classical analytical methods are not suitable due to the heterogeneity of such substances. Conventional biological assays based on the detection of proteins and functional physiologic responses are highly variable in sensitivity and therefore, difficult to standardize. The quantification of expressed genes in contrast, does not require the accumulation of measurable protein and hence is a more sensitive and dynamic method for the functional characterization of complex biological substances. This report describes a standardized system based on real-time polymerase chain reaction (PCR), which allows a reliable stability monitoring and quality control of such preparations, as exemplified by three pro-biotic pharmaceuticals that contain living bacteria of Enterococcus faecalis (Symbioflor-1), Escherichia coli (Symbioflor-2) and a preparation of sterile autolysate of both species (Pro-Symbioflor). This system might be universally applicable to characterize complex biological pharmaceuticals by selecting appropriate sets of target cells and regulated genes.

Cell Line↗

PubMed2002

Cytokine/chemokine messenger-RNA expression profiles in ulcerative colitis and Crohn's disease.

To define mediator profiles in inflamed and noninflamed areas in inflammatory bowel disease (IBD) we analyzed the expression of 35 messenger-RNAs (mRNAs) encoding cytokines, chemokines, and some related molecules in transmural gut tissues (n=138) from patients with ulcerative colitis (UC), Crohn's disease (CD), and inflammatory and normal controls by real-time quantitative reverse transcription polymerase chain reaction. Using sample collectives with a comparable degree of inflammation, most parameters investigated showed similarly increased mRNA expression levels in both active UC and CD. This included proinflammatory cytokines, but also interferon (IFN) gamma and several IFN-gamma inducible chemokines. Only macrophage inflammatory protein (MIP)-2alpha mRNA was expressed at higher levels in inflamed UC vs. CD. IH revealed that MIP-2alpha protein was produced mainly by intestinal epithelial cells. Importantly, in histologically noninflamed/inactive IBD samples mRNAs for several mediators were significantly enhanced, accompanied by elevated levels of migration-inhibition factor related protein (MRP) 14 transcripts. CD14 positive macrophages were found especially in noninflamed/inactive UC, many of which coexpressed the RFD-7 antigen. Our results indicate a substantial overlap in cytokine/chemokine mRNA expression in UC and CD. Elevated mediator expression is evident in noninflamed/inactive areas in both diseases. Local recruitment of MRP-14 positive leukocytes might contribute to this phenomenon. In inactive UC a phenotypically altered population of macrophages expressing CD14 might play an additional role.

Adolescent↗

PubMed2002

Quantitative expression of toll-like receptor 1-10 mRNA in cellular subsets of human peripheral blood mononuclear cells and sensitivity to CpG oligodeoxynucleotides.

The Toll-like receptor (TLR)9 is critical for the recognition of immunostimulatory CpG motifs but may cooperate with other TLRs. We analyzed TLR1-10 mRNA expression by using quantitative real-time PCR in highly purified subsets of human PBMC and determined the sensitivity of these subsets to CpG oligodeoxynucleotides (ODN). TLR1 and TLR6 were expressed in all cell types examined. TLR10 was highly expressed in B cells and weakly expressed in plasmacytoid dendritic cells (PDC). High expression of TLR2 was characteristic for monocytes. PDC and B cells expressed marked levels of TLR7 and TLR9 and were directly sensitive to CpG ODN. In CpG ODN-stimulated PDC and B cells, TLR9 expression rapidly decreased, as opposed to TLR7, which was up-regulated in PDC and decreased in B cells. In monocytes, NK cells, and T cells, TLR7 was absent. Despite low expression of TLR9, monocytes, NK cells, and T cells did not respond to CpG ODN in the absence of PDC but were activated in the presence of PDC. In conclusion, our studies provide evidence that PDC and B cells, but not monocytes, NK cells, or T cells, are primary targets of CpG ODN in peripheral blood. The characteristic expression pattern of TLR1-10 in cellular subsets of human PBMC is consistent with the concept that TLR9 is essential in the recognition of CpG ODN in PDC and B cells. In addition, selective regulation of TLR7 expression in PDC and B cells by CpG ODN revealed TLR7 as a candidate TLR potentially involved in modulating the recognition of CpG motifs.

Adjuvants, Immunologic↗

PubMedDate not supplied

Silencing of X-linked inhibitor of apoptosis (XIAP) decreases gemcitabine resistance of pancreatic cancer cells.

BACKGROUND: The X-linked inhibitor of apoptosis (XIAP) belongs to a family of proteins that suppresses apoptosis by inhibition of caspases in some cancers. It confers resistance to apoptosis induction by chemotherapeutic agents. The aim of this study was to evaluate the influence of XIAP in pancreatic cancer. PATIENTS AND METHODS: Tissue samples from 43 patients with pancreatic adenocarcinoma (median age of 67 years, range from 39-81 years) were analyzed. Pancreatic samples from healthy organ donors (10) and chronic pancreatitis patients (10) served as controls. XIAP expression and localization analysis was carried out by quantitative RT-PCR and immunohistochemistry (IHC). XIAP silencing was achieved by transfection of specifically designed siRNA oligonucleotides. Proliferation and chemotherapy experiments were performed by MTT cell growth assays. RESULTS: There was a 2.1-fold increase of median XIAP mRNA levels in pancreatic cancers compared to controls. Kaplan-Meier analysis indicated a tendency for reduced patient survival with increasing levels of XIAP mRNA (higher levels: 13.4 months; lower levels: 16.1 months). IHC revealed strong XIAP staining in tubular complexes and pancreatic cancer cells. XIAP silencing resulted in a slight reduction of the proliferation of Capan-1 and T3M4 pancreatic cancer cells. In addition, XIAP silencing resulted in increased sensitivity of both cell lines to gemcitabine. CONCLUSION: XIAP is overexpressed in pancreatic cancer and contributes to chemoresistance. Interfering with this pathway may have potential therapeutic role in the treatment of this disease.

Adolescent↗