Biomedical subjects

Diana Dudziak

Publications and source records attributed to Diana Dudziak.

7 recordsLinked to original sources

PubMed2007

Differential antigen processing by dendritic cell subsets in vivo.

Dendritic cells (DCs) process and present self and foreign antigens to induce tolerance or immunity. In vitro models suggest that induction of immunity is controlled by regulating the presentation of antigen, but little is known about how DCs control antigen presentation in vivo. To examine antigen processing and presentation in vivo, we specifically targeted antigens to two major subsets of DCs by using chimeric monoclonal antibodies. Unlike CD8+ DCs that express the cell surface protein CD205, CD8- DCs, which are positive for the 33D1 antigen, are specialized for presentation on major histocompatibility complex (MHC) class II. This difference in antigen processing is intrinsic to the DC subsets and is associated with increased expression of proteins involved in MHC processing.

Amino Acid Sequence↗

PubMed2005

Alternative splicing generates putative soluble CD83 proteins that inhibit T cell proliferation.

CD83 is expressed on mature dendritic cells and activated lymphocytes and has been implicated to play an important role during T cell development in the thymus. In contrast, not much is known about the function of CD83 in the periphery. Soluble forms of CD83 have been detected in the serum, but neither the function nor the mechanism of how these soluble forms of CD83 are generated are fully understood. In this study, we report the identification of four different transcripts of CD83 in unstimulated PBMCs. Sequence analysis demonstrated that the longest form codes for transmembrane CD83 (CD83-TM), whereas the smaller transcripts are splice variants of full-length CD83, coding for putative soluble CD83 proteins. Stimulation of PBMCs with PHA, TNF-alpha, or LPS leads to the up-regulation of the full-length CD83 transcript and to a strong down-regulation of two of the three smaller transcripts. The smallest CD83 splice product can be translated efficiently into protein, and recombinant soluble CD83 shows a strong inhibitory effect on T cell proliferation in MLRs. Our results suggest that the constitutive production of soluble forms of CD83 under steady-state conditions may have an important function in regulating immune homeostasis.

Alternative Splicing↗

PubMed2005

Stable T cell-dendritic cell interactions precede the development of both tolerance and immunity in vivo.

The maturation status of dendritic cells (DCs) determines whether they prime or tolerize T cells. We targeted ovalbumin peptide exclusively to DCs in situ using an antibody to DEC-205 and studied the interaction of DCs with naive CD4(+) T cells in tolerizing or priming conditions. We used two-photon microscopy to simultaneously track antigen-specific OT-II T cells, nonspecific T cells and DCs in lymph nodes of living mice. In both tolerance and immunity, OT-II cells arrested on DCs near high endothelial venules beginning shortly after extravasation and regained their baseline speed by 18 h. Thus, early antigen-dependent T cell arrest on DCs is a shared feature of tolerance and priming associated with activation and proliferation.

Animals↗

PubMed2004

Visualizing dendritic cell networks in vivo.

In the steady state, dendritic cells (DCs) in the lymph node induce T cell tolerance to self antigens. Innate signals trigger the maturation of tissue DCs, which migrate into lymph nodes and activate T cells. To examine DCs in vivo, we produced transgenic mice whose DCs expressed enhanced yellow fluorescent protein. Two-photon microscopy of lymph nodes in live mice showed that most of the steady-state DCs were enmeshed in an extensive network and remained in place while actively probing adjacent T cells with their processes. Mature DCs were more motile than steady-state DCs and were rapidly dispersed and integrated into the sessile network, facilitating their interaction with migrating T cells.

Animals↗

PubMed2004

Epstein-Barr virus nuclear antigen 2 induces interleukin-18 receptor expression in B cells.

Epstein-Barr virus (EBV) latently infects and immortalizes B lymphocytes and causes lymphoproliferative malignancies. We show here that the EBV nuclear antigen EBNA2 induces expression of the 2 chains of the interleukin-18 receptor (IL-18R) in Burkitt lymphoma (BL) cell lines and in nontransformed B cells. Activation of IL-18R expression by EBNA2 is independent of its interaction with the transcriptional repressor RBPJ kappa. It occurs in the absence of any other viral protein but requires de novo synthesis of cellular proteins. IL-18R induction is a highly specific function of EBNA2, because neither other EBV latent proteins nor the cellular proteins c-myc or Notch can exert this effect. Using cDNA microarray expression profiling, we find that the IL-18 receptor expressed in EBV-infected BL cells has signaling capacity, because IL-18 significantly modified gene expression. We report that EBNA2 expression is associated with IL-18R expression in vivo in EBV-positive B-lymphomas from AIDS patients.

B-Lymphocytes↗

PubMed2004

Active NF-kappaB signalling is a prerequisite for influenza virus infection.

Influenza virus still poses a major threat to human health. Despite widespread vaccination programmes and the development of drugs targeting essential viral proteins, the extremely high mutation rate of influenza virus still leads to the emergence of new pathogenic virus strains. Therefore, it has been suggested that cellular cofactors that are essential for influenza virus infection might be better targets for antiviral therapy. It has previously been reported that influenza virus efficiently infects Epstein-Barr virus-immortalized B cells, whereas Burkitt's lymphoma cells are virtually resistant to infection. Using this cellular system, it has been shown here that an active NF-kappaB signalling pathway is a general prerequisite for influenza virus infection of human cells. Cells with low NF-kappaB activity were resistant to influenza virus infection, but became susceptible upon activation of NF-kappaB. In addition, blocking of NF-kappaB activation severely impaired influenza virus infection of otherwise highly susceptible cells, including the human lung carcinoma cell lines A549 and U1752 and primary human cells. On the other hand, infection with vaccinia virus was not dependent on an active NF-kappaB signalling pathway, demonstrating the specificity of this pathway for influenza virus infection. These results might be of major importance for both the development of new antiviral therapies and the understanding of influenza virus biology.

B-Lymphocytes↗

PubMed2003

Latent membrane protein 1 of Epstein-Barr virus induces CD83 by the NF-kappaB signaling pathway.

Epstein-Barr virus (EBV) infects human resting B cells and transforms them in vitro into continuously growing lymphoblastoid cell lines (LCLs). EBV nuclear antigen 2 (EBNA2) is one of the first viral proteins expressed after infection. It is able to transactivate viral as well as cellular target genes by interaction with cellular transcription factors. EBNA2 target genes can be studied easily by using an LCL (ER/EB2-5) in which wild-type EBNA2 is replaced by an estrogen-inducible EBNA2. Since the cell surface molecule CD83, a member of the immunoglobulin superfamily and a marker for mature dendritic cells, appeared on the surface of ER/EB2-5 cells within 3 h after the addition of estrogen, we analyzed the regulation of CD83 induction by EBV in more detail. Despite its rapid induction, CD83 turned out to be an indirect target gene of EBNA2. We could show that the viral latent membrane protein 1 (LMP1) is responsible for the induction of CD83 by using an LCL expressing a ligand- or antibody-inducible recombinant nerve growth factor receptor-LMP1 fusion protein. The inducibility of the CD83 promoter by LMP1 was mediated by the activation of NF-kappaB, as seen by use of luciferase reporter assays using the CD83 promoter and LMP1 mutants. Additionally, fusion constructs of the transmembrane domain of LMP1 and the intracellular signaling domain of CD40, TNF-R1, and TNF-R2 likewise transactivated the CD83 promoter via NF-kappaB. Our studies show that CD83 is also a target of the NF-kappaB signaling pathway in B cells.

Antigens, CD↗