PDE4 Inhibitors Attenuate Fibroblast Chemotaxis and Contraction of Native Collagen Gels

Abstract

Therapies that mitigate the fibrotic process may be able to slow progressive loss of function in many lung diseases. Because cyclic adenosine monophosphate is known to regulate fibroblasts, the current study was designed to evaluate the activity of selective phosphodiesterase (PDE) inhibitors on two in vitro fibroblast responses: chemotaxis and contraction of three-dimensional collagen gels. Selective PDE4 inhibitors, rolipram and cilomilast, each inhibited the chemotaxis of human fetal lung fibroblasts (HFL-1) toward fibronectin in the blindwell assay system (control: 100% versus cilomilast [10 microM]: 40.5 +/- 7.3% versus rolipram: [10 microM] 32.1 +/- 2.7% cells/5 high-power fields; P < 0.05, both comparisons). These PDE4 inhibitors also inhibited contraction of three-dimensional collagen gels (control: 100% versus cilomilast: 167.7 +/- 6.9% versus rolipram: 129.9 +/- 1.9% of initial size; P < 0.05, both comparisons). Amrinone, a PDE3 inhibitor, and zaprinast, a PDE5 inhibitor, had no effect in either system. Prostaglandin E(2) (PGE(2)) inhibited both chemotaxis and gel contraction, and the PDE4 inhibitors shifted the PGE(2) concentration-dependence curve to the left in both systems. The inhibition of endogenous PGE(2) production by indomethacin diminished the effects of the PDE4 inhibitors in both chemotaxis and gel contraction, consistent with the concept that the PDE4 inhibitory effects on fibroblasts are related to the presence of cyclic adenosine monophosphate in the cells. In summary, these in vitro results suggest that PDE4 inhibitors may be able to suppress fibroblast activity and, thus, have the potential to block the development of progressive fibrosis.

Cyclic AMP mediates keratinocyte directional migration in an electric field

“…We have previously demonstrated that the β2-AR-mediated decrease in keratinocyte migration is cAMP independent (Chen et al, 2002), because G proteins and cAMP appear to play an important role in the directional movement of cells towards a Journal of Cell Science 118 (9) (Arai et al, 1997;Jin et al, 2000;Kriebel et al, 2003;Meili and Firtel, 2003;Neptune and Bourne, 1997;Neptune et al, 1999;Sun and Firtel, 2003) and increasing intracellular cAMP inhibits fibroblast chemotaxis (Kohyama et al, 2001;Kohyama et al, 2002) and neutrophil chemotaxis (Armstrong, 1995), we were, therefore, interested to determine whether an increase in intracellular cAMP was responsible for the β-agonist-mediated attenuation of EF- induced directional migration. Increasing intracellular cAMP levels with an active cAMP analog (sp-cAMP), PTX or forskolin did indeed replicate the attenuation of keratinocyte galvanotaxis observed with β-adrenergic agonists, and had no effect on migration rate.…”

“…They are known to regulate several aspects of chemotaxis: the chemoattractant signal is perceived by GPCRs (Merlot and Firtel, 2003), G-proteins play a role in chemotaxis (Arai et al, 1997;Jin et al, 2000;Neptune and Bourne, 1997;Neptune et al, 1999;Sun and Firtel, 2003), locally produced cAMP regulates Dictyostelium discoideum streaming during chemotaxis (Kriebel et al, 2003;Meili and Firtel, 2003), Gβ-null D. discoideum mutants show reduced galvanotaxis (Zhao et al, 2002) and increasing intracellular cAMP inhibits fibroblast chemotaxis (Kohyama et al, 2001;Kohyama et al, 2002) and neutrophil chemotaxis (Armstrong, 1995). For these reasons, we proposed to determine whether intracellular cAMP played a role in EF-mediated directional migration in keratinocytes.…”

The hematopoietic stem cell in chronic phase CML is characterized by a transcriptional profile resembling normal myeloid progenitor cells and reflecting loss of quiescence

“…[18][19][20] We also found decreased expression levels of genes encoding for members of the CXCR4 downstream signaling pathway in CML HSC including phosphoinositol-3-kinase (PI3K) 21,22 and 3-phosphoinositide-dependent protein kinase-1 (PDK1) 22 as well as atypical protein kinase C (aPKC). [22][23][24] With regard to cell migration and chemotaxis, genes encoding for hematopoietic cell-specific DOCK2, 25 PDE4, 26 and PTP4A1 27 were downregulated in CML HSC (Table 1). These results were strengthened by a BioCarta-based pathway analysis showing differential regulation of the pathways cell to cell adhesion signaling, CXCR4 signaling pathway and role of PI3K subunit p85 in actin organization and cell migration in the HSC of CML patients compared to healthy donors (Figure 3).…”

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). Roflumilast mitigates bleomycin-induced lung fibrotic remodeling in rodents (23).…”

“…Cilomilast lowered pulmonary fibrosis which are pathologically quantified examination of bleomycin instilled mice (24). In vitro and animal experimental results suggest that PDE4 inhibitors may be able to inhibit fibroblast activity and, thus, have the potential to prevent of progressive fibrosis of airways and lung parenchyma (22).…”