Smoke on bacterial interactions with airway epithelia
Abstracts
Initial Award Abstract |
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The goal of this research is to determine the cellular and molecular interactions among smoking and bacterial binding and cytotoxicity to lung airway epithelial cells. Imaging microscopy-based methods will be used to study the binding and toxic reactions of bacteria with epithelial cells, and the effects of tobacco smoke on these interactions. Preliminary data combined with work from other laboratories have indicated that a common airway bacterium Pseudomonas aeruginosa is prevented from infecting the lungs because of the effective mechanisms for preventing bacterial access to the critical binding sites on the basal and lateral sides of the cells. It is proposed that tobacco smoke both reduces these airway defense mechanisms and opens the junctions holding the cells together and allows bacterial binding, infection and cell damage. Thus, smoking in combination with bacteria may initiate synergistic interactions leading to tissue damage characteristic of bronchitis and emphysema. Because bacterial binding appears also to activate specific cell regulatory pathways that may lead to inappropriate gene activation, these interactions among smoking, bacteria and the airway epithelial cells may be crucial for initiating lung cancer. The experiments proposed here will provide insights into the interactions that occur at the cellular and molecular level between the bacteria and the epithelial cells in the normal state and during both short and long term exposure to tobacco smoke. It is hoped that this information will provide information relevant to preventing these early, smoking-induced changes in epithelial cell functions. |
Final Report |
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Maintenance of an intact epithelial barrier is critical for the ability of the lungs to prevent access of bacteria and other pathogens to the blood and the rest of the cardiovascular system. An imaging microscope was used to test whether tobacco smoke causes the junctions that attach adjacent epithelial cells in the lung airways to come apart, allowing access of bacteria (normally are retained in the mucus in the airways) to the blood-facing membranes of the epithelial cells. We first tested for interactions between airway epithelial cells and the common gram negative bacterium Pseudomonas aeruginosa (PA) in control condition. PA bind and kill the epithelial cells only after the bacteria have contacted the basal (blood side) surface of the epithelial cells, where the bacteria bind and then secrete a specific toxin directly into the cells. This toxin appears to disrupt the normal functioning of the calcium signaling apparatus in the cells as well as the mitochondria that are used for generating energy. These two events occurred nearly simultaneously, so it was possible that the two functions were both affected by the bacterial toxin, whose function and structure is presently unknown. Thus, these experiments have already contributed to our understanding of how bacteria damage airway epithelial cells. We also used molecular methods to generate bacteria that exhibit green fluorescence so we can track their binding to the epithelial cells in the imaging microscope. Finally, a so-called gene microarray was used to monitor the activity of about 5000 genes in the airway epithelial cells during exposure to tobacco-treated solution. This resulted in the altered activity (both up and down regulation) of more than 50 of these genes, many of which also exhibited altered regulation when PA contacted the blood side membranes of the epithelial cells. The gene responses during exposure to these bacteria indicated that inflammatory reactions are triggered most significantly from bacterial contact with the basolateral surface, as may occur when epithelia are damaged by smoke. The next step will be to make the critical test of whether tobacco affects the epithelial cells in a way that allows the bacteria to gain access to the key blood-side membranes, thereby exposing the epithelial cells to damaging and inflammatory effects of bacteria. |
Publications
| Modulation of cytosolic [Ca] in airway epithelial cells by pseudomonas aeruginosa. |
| Periodical: Infection and Immunity |
Index Medicus: |
| Authors: Jacob T, Lee R, Engel J, and Machen TE |
ART |
| Yr: 0 |
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| Airway epithelial cell polarity determines NFkB-dependent gene regulation in response to pseudomonas aeruginosa. |
| Periodical: Pediatric Pulmonology. Supplement |
Index Medicus: |
| Authors: Hybiske KJ, Huang V, Ichikawa J, Lory S, and Machen T |
ABS |
| Yr: 2001 |
Vol: |
Nbr: 284 |
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Pg: |
| Modulation of cytosolic [Ca] in airway epithelial cells by pseudomonas aeruginosa. |
| Periodical: Infection and Immunity |
Index Medicus: |
| Authors: Jacob T, Lee R, Engel J, and Machen TE |
ART |
| Yr: 0 |
Vol: |
Nbr: |
Abs: |
Pg: |
| Airway epithelial cell polarity determines NFkB-dependent gene regulation in response to pseudomonas aeruginosa. |
| Periodical: Pediatric Pulmonology. Supplement |
Index Medicus: |
| Authors: Hybiske KJ, Huang V, Ichikawa J, Lory S, and Machen T |
ABS |
| Yr: 2001 |
Vol: |
Nbr: 284 |
Abs: |
Pg: |
