Biomedical subjects

Ursula Panzner

Publications and source records attributed to Ursula Panzner.

5 recordsLinked to original sources

PubMed2006

Gene expression pattern in human brain endothelial cells in response to Neisseria meningitidis.

To extend our knowledge of target proteins in endothelial cells infected with the meningitis-causing pathogen Neisseria meningitidis, we characterized the interaction between the bacterial and human brain microvascular endothelial cell (HBMEC) monolayers. By use of human cDNA microarrays, transcriptional analysis revealed distinct responses to 4 and 8 h of infection. We also addressed the question of whether the major virulence factor of meningococci, i.e., the capsule, influences the host cell response. Of the 1,493 (at 4 h postinfection) and 1,246 (at 8 h postinfection) genes with altered expression upon bacterial contact, about 49.4% and 45%, respectively, depended on capsule expression. In particular, we identified an increase of expression for genes encoding proteins involved in bacterial adhesion and invasion. High levels of apoptosis-related gene (bad, bak, asp, and immediate-early response gene 1) expression could also be detected in infected cells. Further analyses confirmed that HBMECs displayed several hallmarks of apoptosis in response to N. meningitidis infection, namely, phosphatidylserine translocation and activation of caspase 3 and AMP-activated protein kinase alpha. Moreover, several differentially regulated genes not previously known to respond to meningococcal infection were identified. Of these, genes encoding cell adhesion proteins (CD44, CD98, and CD99), genes involved in downstream signaling of integrins (integrin-linked kinase, mitogen-activated protein kinase kinase 1, and mitogen-activated protein kinase kinase kinase 10) as well as negative regulators of these pathways (dual-specificity phosphatases 1, 5, and 14 and G protein pathway suppressor 2), and genes involved in cytoskeleton reorganization (those encoding Arp2/3, p34-arc, actinin alpha 1, vasodilatator-stimulated protein, and Wiskott-Aldrich syndrome protein) were the most prominent. This global transcriptional analysis creates a new platform for further molecular and cellular analysis of the interaction between N. meningitidis and target cells.

AMP-Activated Protein Kinases↗

PubMed2006

Intracellular survival and replication of Neisseria meningitidis in human brain microvascular endothelial cells.

To cause meningitis the extracellular pathogen Neisseria meningitidis has to traverse the blood-cerebrospinal fluid (B-CSF) barrier. Postulating a transcellular passage, meningococci (MC) have been shown to adhere to and enter B-CSF barrier forming human brain microvascular endothelial cells (HBMEC). Furthermore, electron microscopy studies demonstrated that intracellular MC reside within membrane-bound compartments, both solitary and in groups. To investigate the ability of MC to survive and replicate intracellularly, prolonged gentamicin protection assays were performed. Encapsulated bacteria were found to survive and, after an initial delay, to replicate within HBMEC, whereas the number of intracellular capsule-deficient mutants decreased continuously. This strongly suggests that the capsule plays a pivotal role in the intracellular survival of MC. Further investigations were initiated to characterise the membrane-bound compartment, the Neisseria-containing vacuole (NCV). Immunfluorescence microscopy studies showed that NCVs interact with the endocytic pathway acquiring the early endosomal marker protein, transferrin receptor (TfR), and the late endosomal/lysosomal marker protein Lamp-1.

Brain↗

PubMed2003

Transcriptome-based antigen identification for Neisseria meningitidis.

The identification of suitable antigens is crucial to successful vaccine development based on subunit approaches. While many methods exist for the identification of vaccine candidates which are surface-exposed or secreted, immunogenic and conserved, contain B and T cell epitopes, most of these have a major drawback: they do not yield any information on whether the antigen is indeed expressed by the pathogen during infection. However, DNA microarrays offer a novel tool for the investigation of the transcriptional activity of all genes of a pathogenic microorganism under in vivo conditions. Employing whole genome DNA microarrays, we have analyzed the transcriptome of Neisseria meningitidis serogroup B bacteria during different stages of infection, i.e. exposure to human serum and the interaction with human epithelial and endothelial cells. Combined with data derived from genome-based approaches (such as reverse vaccinology) and immunogenicity studies, this novel transcriptome-based antigen identification should reveal ideal vaccine candidates against serogroup B meningococcal infection.

Antigens, Bacterial↗

PubMed2003

Transcriptome analysis of Neisseria meningitidis during infection.

Neisseria meningitidis is the cause of septicemia and meningococcal meningitis. During the course of infection, N. meningitidis encounters multiple environments within its host, which makes rapid adaptation to environmental changes a crucial factor for neisserial pathogenicity. Employing oligonucleotide-based DNA microarrays, we analyzed the transcriptome of N. meningitidis during two key steps of meningococcal infection, i.e., the interaction with epithelial cells (HeLa cells) and endothelial cells (human brain microvascular endothelial cells). Seventy-two genes were differentially regulated after contact with epithelial cells, and 48 genes were differentially regulated after contact with endothelial cells, including a considerable proportion of well-known virulence genes. While a considerable number of genes were in concordance between bacteria adherent to both cell types, we identified several open reading frames that were differentially regulated in only one system. The data obtained with this novel approach may provide insight into the pathogenicity mechanisms of N. meningitidis and could demonstrate the importance of gene regulation on the transcriptional level during different stages of meningococcal infection.

Bacterial Adhesion↗

PubMed2002

Analysis of the heat shock response of Neisseria meningitidis with cDNA- and oligonucleotide-based DNA microarrays.

Oligonucleotide- and cDNA-based microarrays comprising a subset of Neisseria meningitidis genes were assessed for study of the meningococcal heat shock response and found to be highly suitable for transcriptional profiling of N. meningitidis. Employing oligonucleotide arrays encompassing the entire genome of N. meningitidis, we analyzed the meningococcal heat shock response on a global scale and identified 55 heat shock-deregulated open reading frames (34 induced and 21 repressed).

DNA, Bacterial↗