Epithelial cells and fibroblasts.

Chronic obstructive pulmonary disease (COPD) is characterized by acute and chronic alterations in the cellular composition structure of the airways and alveoli. Much attention has been focused on the increase in inflammatory cells present both within the airway lumen and within the airway wall. The parenchymal cells of the airway are intimately involved in the recruitment and activation of these inflammatory cells. Conversely, the behaviour of parenchymal cells can be modulated by inflammatory cells. The parenchymal cells can also alter the structural elements present within the airway leading to architecture changes which can impair lung function. Finally, epithelial cells and fibroblasts can directly modify each other's behaviour. The activity of these cells, therefore, undoubtedly can play a variety of roles in the pathophysiologic processes which underlie COPD.