Gene Expression Pattern in Human Brain Endothelial Cells in Response to Neisseria meningitidis

Abstract

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 ␣. 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 (dualspecificity 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.

Concepts and Mechanisms: Crossing Host Barriers

“…This response was dependent on the GBS b-h/c toxin, the transcriptional regulator of virulence, CovR and PilA expression (Doran et al 2003;Lembo et al 2010;Banerjee et al 2011). Additional in vitro studies with S. pneumoniae, HiB, S. typhimurium, E. coli K1, Streptococcus suis, L. monocytogenes, and N. meningitidis reveal a similar core BMEC transcriptional response that results in the induction of neutrophil signaling pathways (Wilson and Drevets 1998;Vadeboncoeur et al 2003;Galanakis et al 2006;Schubert-Unkmeir et al 2007;Banerjee et al 2010;van Sorge et al 2011). Continued exposure and invasion of the pathogen may result in overactivation of BBB endothelium and lead to increased inflammation that may ultimately compromise BBB integrity.…”

Cryptococcus neoformans Promotes Its Transmigration into the Central Nervous System by Inducing Molecular and Cellular Changes in Brain Endothelial Cells

“…Interestingly, studies of the brain endothelium challenged with the encapsulated bacterium Neisseria meningitidis revealed changes in the expression of genes encoding cytoskeletal proteins, likely indicating a similar reorganization of the cytoskeleton as observed with C. neoformans (45). N. meningitidis is a common cause of bacterial meningitis, and disruption of the BBB is a hallmark event in this disease (45).…”

Meningococcal Outer Membrane Protein NhhA Is Essential for Colonization and Disease by Preventing Phagocytosis and Complement Attack

“…Several lines of evidence have demonstrated that the expression of certain meningococcal outer membrane components is regulated upon contact with the host epithelium, thereby facilitating meningococcal colonization (6,33). In a proteomic analysis, we identified several meningococcal proteins whose expression was upregulated in bacteria attached to host cells compared to their levels in bacteria alone (unpublished results).…”