GM-CSF regulates a PU.1-dependent transcriptional program determining the pulmonary response to LPS.

Alveolar macrophages (AMs) normally respond to lipopolysaccharide (LPS) by activating Toll-like receptor (TLR)-4 signaling, a mechanism critical to lung host defense against gram-negative bacteria such as Pseudomonas aeruginosa. Because granulocyte macrophage colony-stimulating factor (GM-CSF)-deficient (GM(-/-)) mice are hyporesponsive to LPS, we evaluated the role of GM-CSF in TLR-4 signaling in AMs. Pulmonary TNF-alpha levels and neutrophil recruitment 4 h after intratracheal administration of Pseudomonas LPS were reduced in GM(-/-) compared with wild-type (GM(+/+)) mice.

Hypoxia actively represses transcription by inducing negative cofactor 2 (Dr1/DrAP1) and blocking preinitiation complex assembly.

Hypoxia is a growth inhibitory stress associated with multiple disease states. We find that hypoxic stress actively regulates transcription not only by activation of specific genes but also by selective repression. We reconstituted this bimodal response to hypoxia in vitro and determined a mechanism for hypoxia-mediated repression of transcription.

p53 targets chromatin structure alteration to repress alpha-fetoprotein gene expression.

Many of the functions ascribed to p53 tumor suppressor protein are mediated through transcription regulation. We have shown that p53 represses hepatic-specific alpha-fetoprotein (AFP) gene expression by direct interaction with a composite HNF-3/p53 DNA binding element. Using solid-phase, chromatin-assembled AFP DNA templates and analysis of chromatin structure and transcription in vitro, we find that p53 binds DNA and alters chromatin structure at the AFP core promoter to regulate transcription.

Regulation of gap junctional communication by a pro-inflammatory cytokine in cystic fibrosis transmembrane conductance regulator-expressing but not cystic fibrosis airway cells.

Airway inflammation is orchestrated by cell-cell interactions involving soluble mediators and cell adhesion molecules. Alterations in the coordination of the multicellular process of inflammation may play a major role in the chronic lung disease state of cystic fibrosis (CF). The aim of this study was to determine whether direct cell-cell interactions via gap junctional communication is affected during the inflammatory response of the airway epithelium.

Incomplete regulation of NF-kappaB by IkappaBalpha during respiratory syncytial virus infection in A549 cells.

Respiratory syncytial virus (RSV) infection of airway epithelial cells results in persistent NF-kappaB activation and NF-kappaB-mediated interleukin-8 production. Previous studies in airway epithelial cells demonstrated that tumor necrosis factor alpha (TNF-alpha)-induced NF-kappaB activation is transient due to regulation by IkappaBalpha. However, during RSV infection, IkappaBalpha has only a partial inhibitory effect on NF-kappaB activation.

Inhibition of TNF-alpha-induced NF-kappaB activation and IL-8 release in A549 cells with the proteasome inhibitor MG-132.

The working hypothesis of the studies described herein was that inhibition of proteasome-mediated IkappaB degradation would inhibit TNF-alpha-induced nuclear factor-kappaB (NF-kappaB) activation, interleukin-8 (IL-8) gene transcription, and IL-8 protein release in A549 cells. Mutational analysis of the 5' flanking region of the IL-8 gene confirmed that an intact NF-kappaB site is necessary for TNF-alpha-induced IL-8 gene transcription. The addition of TNF-alpha to A549 cells resulted in rapid loss of IkappaB from the cytoplasm of cells, associated with a corresponding increase in NF-kappaB-binding activity in nuclear extracts from the cells.

Mechanism of RSV-induced IL-8 gene expression in A549 cells before viral replication.

Previous studies demonstrated that respiratory syncytial virus (RSV) infection of A549 cells induced interleukin (IL)-8 gene expression and protein release from the cells as early as 2 h after treatment [M. A. Fiedler, K.

Inhibition of viral replication reverses respiratory syncytial virus-induced NF-kappaB activation and interleukin-8 gene expression in A549 cells.

Previous studies have demonstrated that respiratory syncytial virus (RSV) infection of airway epithelial cells results in the expression of a number of cytokines, such as interleukin-8 (IL-8), that are transcriptionally regulated by nuclear factor kappaB (NF-kappaB). In the studies reported here, we demonstrate that treatment of RSV-infected A549 cells with 100 microg of ribavirin (a viral replication inhibitor) per ml results in reversal of RSV-induced NF-kappaB activation, IL-8 mRNA expression, and IL-8 protein production in A549 cells. These data confirm that viral replication is a key step in RSV-induced NF-kappaB activation and IL-8 production.

Respiratory syncytial virus increases IL-8 gene expression and protein release in A549 cells.

The mechanism of respiratory syncytial virus (RSV)-induced inflammation in the airways of infants and children is not fully understood. We hypothesized that RSV directly induces interleukin (IL)-8 gene expression in airway epithelial cells, independent of IL-1 beta and tumor necrosis factor-alpha (TNF-alpha) production. Exposure of A549 cells (an airway epithelial cell line) to RSV resulted in increased IL-8 mRNA expression and IL-8 protein release from the cells as early as 2 h after treatment.