Structural Cells Sample Clauses

Structural Cells. The ability of structural cells (epithelial cells, fibroblasts, smooth muscle cells and endothelial cells) to synthesise a wide array of inflammatory mediators including proinflammatory cytokines and chemokines implicate these cells as potential inflammatory effector cells in asthmatic airways (Figure 1.4)(Xxxxxxx & El Xxxxxx 2004). The exact contribution of specific structural cell types to the overall production of mediators involved in inflammatory cell influx to the airways is unclear (Xxxxxxx & El Xxxxxx 2004). Continuation of airway inflammation in asthma likely results from the coordinated expression of several cytokines and chemokines by different cell types working at different time points. Airways are embedded in the mechanically dynamic environment of the lung. In the adult lung, the mechanical environment is defined by a dynamic balance of surface, tissue, and muscle forces (Niimi 2011). Diseases of the airways modulate both the mechanical stresses to which the airways are exposed as well as the structure and mechanical behaviour of the airways (Niimi 2011). For instance, in asthma, activation of ASM abruptly changes the airway size and stress state within the airway wall (Xxxxxxxxxxxx & Xxxxxx 2006). The folding of the airway wall into a rosette pattern during bronchoconstriction creates a complex stress field, with the highest stresses compressing the epithelial layer at the inner surface of the airway wall (Niimi 2011). The epithelial cells lining the airway possess the capacity to modulate the inflammatory environment of the airway wall, and produce factors that influence the recruitment, proliferation, and activity of fibroblasts and ASM cells (Xxxxxxxxxxxx & Xxxxxx 2001). Especially, a prominent role has been identified for the epithelium in transducing mechanical stresses (Niimi 2011). A variety of in vitro studies have demonstrated that airway epithelial cells, along with lung fibroblasts and ASM cells, are responsive to mechanical stimuli (Niimi 2011). Airway epithelial cells exposed to compressive stresses equivalent to those occurring in the constricted airway increase expression of genes relevant to airway remodelling such as matrix metalloproteinase (MMP)-9, endothelins 1 and 2, TGF-β2, and increase the synthesis of fibronectin, collagen types III and V by cocultured fibroblasts (Xxxxxxxxxxxx & Xxxxxx 2006;Xxxxxxxxxxxx et al. 2003). These findings demonstrate that mechanical stress may contribute to the remodelling of the asthmatic...