Study of the activation of pulmonary cells by cigarette smoke extract or by neutrophil elastase associated with lipopolysaccharide : Study of the effects of an inhibitor of phosphodiesterase type 4, roflumilas-N Oxyde ; Etude de l'activation de cellules pulmonaires par un extrait de fumée de cigarette ou par l'élastase du neutrophile associés au lipopolysaccharideEtude des effets d'un inhibiteur de phophodiestérase de type 4, le roflumilast

Chronic obstructive pulmonary disease (COPD) is a pathology characterized by an abnormal inflammatory response and associated with a destruction of lung parenchyma and loss of lung elasticity, leading to an airway limitation not fully reversible. Tobacco smoking continues to be a major cause of COPD. Cigarette smoke activates epithelial cells and resident macrophages by releasing proteases and chemokines. This phenomenon is responsible of the migration of inflammatory cells in the lung tissue such as neutrophils, macrophages and lymphocytes. These cells are able to release proteolytic enzymes leading to the degradation of components of the extracellular matrix. Among these proteases, neutrophil elastase (NE) seems to stimulate the secretion of cytokines involved in chronic inflammation. Strong evidence shows that recurrent bacterial infections contribute to the inflammatory process and consequently to the worsening of COPD. Based on these observations, we studied the early events in the development of COPD associated with recurrent bacterial infection. Initially we showed that the combination of a cigarette smoke extract associated with low doses of LPS is able to synergistically increase the release of chemokines, by alveolar epithelial cells through the activation of MAP kinase signaling pathways ERK1/2 and JAK/STAT. We also demonstrated that the phosphodiesterase 4 inhibitor, roflumilast N-oxide (RNO) inhibits the secretion of these cytokines, thereby inactivating pathways JAK/STAT and ERK1/2. Moreover, we have demonstrated that neutrophil elastase (NE) can lead to the release of chemokines by alveolar epithelial cells by activating the p38 signaling pathway. Moreover the treatment of the cells with roflumilast N-oxide significantly reduces the production of these chemokines. This in vitro model demonstrates the synergistic effect of CSE associated with LPS on the release of cytokines and activation of signaling pathways. This effect could be responsible for the progression and exacerbation of COPD. Our study ...