PDE4 inhibitors roflumilast and rolipram augment PGE₂ inhibition of TGF-β1-stimulated fibroblasts

Abstract

Fibrotic diseases are characterized by the accumulation of extracellular matrix together with distortion and disruption of tissue architecture. Phosphodiesterase (PDE)4 inhibitors, by preventing the breakdown of cAMP, can inhibit fibroblast functions and may be able to mitigate tissue remodeling. Transforming growth factor (TGF)-beta1, a mediator of fibrosis, can potentially modulate cAMP by altering PGE(2) metabolism. The present study assessed whether PDE4 inhibitors functionally antagonize the profibrotic activity of fibroblasts stimulated by TGF-beta1. The PDE4 inhibitors roflumilast and rolipram both inhibited fibroblast-mediated contraction of three-dimensional collagen gels and fibroblast chemotaxis toward fibronectin in the widely studied human fetal lung fibroblast strain HFL-1 and several strains of fibroblasts from adult human lung. Roflumilast was approximately 10-fold more potent than rolipram. There was a trend for PDE4 inhibitors to inhibit more in the presence of TGF-beta1 (0.05 < P < 0.08). The effect of the PDE4 inhibitors was mediated through cAMP-stimulated protein kinase A (PKA), although a PKA-independent effect on gel contraction was also observed. The effect of PDE4 inhibitors depended on fibroblast production of PGE(2) and TGF-beta1-induced PGE(2) production. PDE4 inhibitors together with TGF-beta1 resulted in augmented PGE(2) production together with increased expression of COX mRNA and protein. The present study supports the concept that PDE4 inhibitors may attenuate fibroblast activities that can lead to fibrosis and that PDE4 inhibitors may be particularly effective in the presence of TGF-beta1-induced fibroblast stimulation.

Attenuation of Inhibitory Prostaglandin E2 Signaling in Human Lung Fibroblasts Is Mediated by Phosphodiesterase 4

“…After pretreatment, cells were trypsinized, counted, and resuspended in serum-free (SF) medium alone or in SF medium with 0.1 mM PGE2 and then assessed for migration toward human fibronectin in a Boyden blindwell chamber (Figure 1a). Control cells were susceptible to PGE2 (0.1 mM)-mediated inhibition of chemotaxis, consistent with previous results from multiple laboratories (7)(8)(9)(10). Cells pretreated with PGE2 for 24 hours demonstrated increased baseline chemotaxis.…”

“…Lung fibroblasts are crucial in maintaining tissue structure (6). The inflammatory mediator PGE2 is a potent cAMP-dependent inhibitor of lung fibroblast repair functions, including migration (7)(8)(9)(10). PGE2-mediated inhibition of fibroblast repair responses has been related to COPD severity and to emphysema.…”

“…Previous studies evaluating PGE2 inhibition of fibroblast repair have focused on short-term responses (7)(8)(9)(10). Attenuation of signaling in the face of chronic exposure to stimuli is a common autoregulatory mechanism.…”

Roles of roflumilast, a selective phosphodiesterase 4 inhibitor, in airway diseases

“…Roflumilast antagonizing profibrotic activity of fibroblasts stimulated by tumor growth factor β (TGF-β) has been shown from in vitro study (21). Rolipram and cilomilast attenuating fibroblast chemotaxis has been shown in in experimental study (22).…”

Beta2-Agonist Induced Camp Is Decreased In Asthmatic Airway Smooth Muscle Due To Increased PDE4D

“…The pan-PDE inhibitor 3-Isobutyl-1-methylxanthine (IBMX) was used at 0.5 mM [20]. The PDE4 inhibitors roflumilast 1 mM (Nycomed) and cilomilast 1 mM (GSK) and the PDE3 inhibitor milrinone (10 mM, SigmaAldrich, Castle Hill, NSW) were utilized at the indicated concentrations based on reports showing complete and selective inhibition of their respective isoenzymes [20,21,22,23,24].…”