Division des Soins Intensifs de Médecine, Hôpital Cantonal Universitaire, 1211 Genève 14, Switzerland
Keywords: lung; cytokines, growth factors; inflammation; cell cultures: organ-specific; reduction
Duration: 3 years Project Completion: 2000
Background and Aim
Critically ill patients with sepsis and adult respiratory distress syndrome (ARDS) are frequently submitted to prolonged positive pressure mechanical ventilation (MV) to prevent pulmonary failure. It has recently been recognized that MV per se can induce significant lung injury. Evidence for this arises mainly from animal studies. This project was designed to develop an in vitro model to study MV-induced lung inflammation. In this model, lung cells were submitted to a prolonged cyclic pressure-stretching strain resembling that of conventional MV.
Method and Results
Primary human lung cells or cell lines were cultured on a stretchable silastic membrane forming the bottom of a 12-well plexiglas® box. The box was connected to an adult ventilator and "ventilated" for up to 36 hours at 20 cycles/min with a pressure-volume regimen resembling that of MV. Several lung cell types were tested in this model. The alveolar macrophage was identified as the main cellular source of key inflammatory mediators, such as tumor necrosis factor, the chemokine interleukin (IL)-8, and matrix metalloproteinase-9, produced during mechanical ventilation. Mechanical ventilation also induced low levels of IL-8 secretion by human alveolar epithelial type II-like cells. Other lung cell types such as endothelial cells, bronchial cells, and fibroblasts failed to produce IL-8 in response to mechanical ventilation (1,2).
Conclusions and Relevance for 3R
The described in vitro model provides mechanistic information at the molecular and cellular levels for the lung inflammation observed during mechanical ventilation of patients. It allows mechanical stress-induced signaling pathways to be explored without the use of animal models, and permits the testing of novel ventilatory strategies and adjunctive substances aimed at modulating cell activation induced by mechanical ventilation.
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