Inflammation may affect the barrier function of tight junctions. Several integrins and growth factors produced by inflammatory cells influence synthesis or organization of tight junction components leading to enhanced permeability and exposure of tissues to antigens [15, 46, 47] . Increased permeability of tight junctions is one factor lying behind the pathophysiology of colitis ulcerosa and Crohn's disease [47] . Also in chronic bronchitis and asthma airway epithelial cells are exposed to chronic stimulation by integrins and growth factors predisposing the bronchial wall to dysregulation of the epithelial barrier function further provoking the chronic infection [46, [48] [49] [50] .