The selective phosphodiesterase 4 inhibitor RP 73-401 reduced matrix metalloproteinase 9 activity and transforming growth factor-β release during acute lung injury in mice:: The role of the balance between tumor necrosis factor-α and interleukin-10

Matrix metalloproteinases (MMPs) and transforming growth factor (TGF)-beta are involved in airway remodeling associated with the inflammatory process. In this study, we investigated the effect of RP 73-401 (piclamilast), a selective phosphodiesterase-4 inhibitor, on MMP-9 activity and TGF-beta production in two murine models of acute inflammation. In the first model, the lipopolysaccharide (LPS)-induced increase in neutrophils, MMP-9 activity, and tumor necrosis factor (TNF)-alpha and TGF-beta release in bronchoalveolar lavage (BAL) was significantly reduced by RP 73-401 pretreatment. In contrast, the BAL interleukin (IL)-10 level was decreased by LPS but restored by RP 73-401. IL-10 administration in LPS-exposed mice elicited a significant reduction in BAL neutrophilia, MMP-9 activity, and TNF-alpha release but not in TGF-beta production. In the second model, RP 73-401 inhibited BAL neutrophils but not MMP-9 activity and TGF-beta production that were induced by intranasal TNF-alpha. We demonstrated that RP 73-401 might modulate the expression of airway remodeling-associated mediators such as MMP-9 and TGF-beta and that this effect seemed to be at least partially mediated by the balance between TNF-alpha and IL-10.