Pan-Phosphodiesterase Inhibitors Attenuate TGF-β-Induced Pro-Fibrotic Phenotype in Alveolar Epithelial Type II Cells by Downregulating Smad-2 Phosphorylation

Abstract

Airway remodeling is a pathological process that accompanies many chronic lung diseases. One of the important players in this process are epithelial cells, which under the influence of pro-inflammatory and pro-fibrotic factors present in the airway niche, actively participate in the remodeling process by increasing extracellular matrix secretion, acquiring migration properties, and overproducing pro-fibrotic transducers. Here, we investigated the effect of three new 8-arylalkylamino- and 8-alkoxy-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl-N-(5- (tert-butyl)-2-hydroxyphenyl)butanamides (1, 2, and 3), representing prominent pan-phosphodiesterase (pan-PDE) inhibitors on transforming growth factor type β (TGF-β)-induced alveolar epithelial type II cells (A549 cell line) of a pro-fibrotic phenotype. Our results demonstrate for the first time the strong activity of pan-PDE inhibitors in the prevention of TGF-β-induced mesenchymal markers’ expression and A549 cells’ migration. We also showed an increased p-CREB and decreased p-Smad-2 phosphorylation in TGF-β-induced A549 cells treated with 1, 2, and 3 derivatives, thereby confirming a pan-PDE inhibitor mesenchymal phenotype reducing effect in alveolar epithelial type II cells via suppression of the canonical Smad signaling pathway. Our observations confirmed that PDE inhibitors, and especially those active against various isoforms involved in the airway remodeling, constitute an interesting group of compounds modulating the pro-fibrotic response of epithelial cells.

circGRHPR inhibits aberrant epithelial-mesenchymal transformation progression of lung epithelial cells associated with idiopathic pulmonary fibrosis

“…All media were enhanced with a 10% concentration of fetal bovine serum (cat# A6901FBS, Invigentech, USA). Similar to previous studies (Li et al 2020a ; Wojcik-Pszczola et al 2022 ), cells were starved overnight and further cultured in serum-depleted medium (1%) supplemented with TGF-β1 (10 ng/mL, cat# 10,804-HNAC, Sino Biological, CHN) for 48 h to induce the phenotype of EMT progression. All cells were incubated in a temperature-controlled environment at 37 °C with a CO 2 concentration of 5%.…”

Perspectives of PDE inhibitor on treating idiopathic pulmonary fibrosis

“…First, the PAN-PDE has significant inhibitory activity against multiple PDE isoforms, including PDE1, PDE3, PDE4, PDE5, PDE7, and PDE8, which are involved in airway remodeling and the development of pulmonary fibrosis ( Wright et al, 1998 ; Fuhrmann et al, 1999 ). And next, considering the cAMP signaling compartmentalization during EMT, a different composition of individual isoforms within the cellular compartments cannot be ruled out ( Zuo et al, 2019b ; Wójcik-Pszczoła et al, 2022 ). In vitro , the pan-PDE inhibitors could inhibit the TGF-β-induced expression of several markers, including vimentin, fibronectin, collagen I, α-smooth muscle actin, N-cadherin, and snail-1 transcription factor in alveolar epithelial type II cells ( Wójcik-Pszczoła et al, 2022 ).…”

“…And next, considering the cAMP signaling compartmentalization during EMT, a different composition of individual isoforms within the cellular compartments cannot be ruled out ( Zuo et al, 2019b ; Wójcik-Pszczoła et al, 2022 ). In vitro , the pan-PDE inhibitors could inhibit the TGF-β-induced expression of several markers, including vimentin, fibronectin, collagen I, α-smooth muscle actin, N-cadherin, and snail-1 transcription factor in alveolar epithelial type II cells ( Wójcik-Pszczoła et al, 2022 ).…”