Mono- and co-cultures of bronchial and alveolar epithelial cells respond differently to pro-inflammatory stimuli and their modulation by salbutamol and budesonide.

Aim of this study was to investigate the changes in transport and effectiveness of salbutamol sulphate (SAL) and budesonide (BD) following stimulation with transforming growth factor-β (TGF-β) in mono- and co-culture models of bronchial and alveolar epithelium. Primary bronchial and alveolar epithelial cells, air interface grown on filters either as mono- cultures or in co- culture with airway smooth muscle cells or alveolar macrophages, respectively, were stimulated with TGF-β. The biological response was modulated by depositing aerosolized SAL on bronchial and BD on alveolar models, respectively. Barrier integrity, permeability to fluorescein-Na, transport of the deposited drug and the pharmacological response to SAL (cAMP and IL-8 levels) or BD (IL-6 and -8 levels) were measured. While stimulation with TGF-β did not have any significant effect on the transepithelial electrical resistance and permeability to fluorescein-Na in mono- and co- culture models, transport of SAL and BD were affected in cultures from some of the patients (6 out of 10 for bronchial and 2 out of 4 for alveolar cells). The bronchial co-culture showed a better responsiveness to SAL in terms of cAMP release than the monoculture. In contrast, difference between alveolar mono- and co- cultures to TGF-β mediated interleukin release and its modulation by BD was less pronounced. Our data point to intrinsic differences in the transport of and responsiveness to SAL and BD when epithelial cell cultures originate from different patients. Moreover, if the biological responses (e.g. IL-8, cAMP) involve communication between different cell types, co-culture models are more potent to measure such effects than mono-cultures.