Cortisol limits selected actions of synthetic glucocorticoids in the airway epithelium.

Cortisol, a physiologic glucocorticoid (GC), is essential for growth and differentiation of the airway epithelium. Epithelial function influences inflammation in chronic respiratory diseases. Synthetic GCs, including inhaled corticosteroids, exert anti-inflammatory effects in airway epithelium by transactivation of genes and by inhibition of proinflammatory cytokine release. We examined the effect of cortisol on the actions of synthetic GCs in the airway epithelium, demonstrating that cortisol acts like a partial agonist at the GC receptor (GR), limiting GC-induced GR-dependent transcription in the BEAS-2B human bronchial epithelial cell line. Cortisol also limited the inhibition of granulocyte macrophage colony-stimulating factor release by synthetic GCs in TNF-α-activated BEAS-2B cells. The relevance of these findings is supported by observations on tracheal epithelium obtained from mice treated for 5 d with systemic GC, showing limitations in selected GC effects, including inhibition of IL-6. Moreover, gene transactivation by synthetic GCs was compromised by standard air-liquid interface (ALI) growth medium cortisol concentration (1.4 µM) in the ALI-differentiated organotypic culture of primary human airway epithelial cells. These findings suggest that endogenous corticosteroids may limit certain actions of synthetic pharmacological GCs and contribute to GC insensitivity, particularly when corticosteroid levels are elevated by stress.-Prodanovic, D., Keenan, C. R., Langenbach, S., Li, M., Chen, Q., Lew, M. J., Stewart, A. G. Cortisol limits selected actions of synthetic glucocorticoids in the airway epithelium.

A Non-canonical Pathway with Potential for Safer Modulation of Transforming Growth Factor-ß1 in Steroid-Resistant Airway Diseases.

Impaired therapeutic responses to anti-inflammatory glucocorticoids (GC) in chronic respiratory diseases are partly attributable to interleukins and transforming growth factor ß1 (TGF-ß1). However, previous efforts to prevent induction of GC insensitivity by targeting established canonical and non-canonical TGF-ß1 pathways have been unsuccessful. Here we elucidate a TGF-ß1 signaling pathway modulating GC activity that involves LIM domain kinase 2-mediated phosphorylation of cofilin1. Severe, steroid-resistant asthmatic airway epithelium showed increased levels of immunoreactive phospho-cofilin1. Phospho-cofilin1 was implicated in the activation of phospholipase D (PLD) to generate the effector(s) (lyso)phosphatidic acid, which mimics the TGF-ß1-induced GC insensitivity. TGF-ß1 induction of the nuclear hormone receptor corepressor, SMRT (NCOR2), was dependent on cofilin1 and PLD activities. Depletion of SMRT prevented GC insensitivity. This pathway for GC insensitivity offers several promising drug targets that potentially enable a safer approach to the modulation of TGF-ß1 in chronic inflammatory diseases than is afforded by global TGF-ß1 inhibition.

Casein Kinase 1δ/ε Inhibitor, PF670462 Attenuates the Fibrogenic Effects of Transforming Growth Factor-ß in Pulmonary Fibrosis.

Transforming growth factor-beta (TGF-ß) is a major mediator of fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). However, therapeutic global inhibition of TGF-ß is limited by unwanted immunosuppression and mitral valve defects. We performed an extensive literature search to uncover a little-known connection between TGF-ß signaling and casein kinase (CK) activity. We have examined the abundance of CK1 delta and epsilon (CK1δ/ε) in lung tissue from IPF patients and non-diseased controls, and investigated whether inhibition of CK1δ/ε with PF670462 inhibits pulmonary fibrosis. CK1δ/ε levels in lung tissue from IPF patients and non-diseased controls were assessed by immunohistochemistry. Anti-fibrotic effects of the CK1δ/ε inhibitor PF670462 were assessed in pre-clinical models, including acute and chronic bleomycin mouse models and in vitro experiments on spheroids made from primary human lung fibroblast cells from IPF and control donors, and human A549 alveolar-like adenocarcinoma-derived epithelial cells. Increased expression of CK1δ and ε in IPF lungs compared to non-diseased controls was accompanied by increased levels of the product, phospho-period 2. In vitro, PF670462 prevented TGF-ß-induced epithelial-mesenchymal transition. The stiffness of IPF-derived spheroids was reduced by PF670462 and TGF-ß-induced fibrogenic gene expression was inhibited. The CK1δ/ε inhibitor PF670462 administered systemically or locally by inhalation prevented both acute and chronic bleomycin-induced pulmonary fibrosis in mice. PF670462 administered in a 'therapeutic' regimen (day 7 onward) prevented bleomycin-induced lung collagen accumulation. Elevated expression and activity of CK1 δ and ε in IPF and anti-fibrogenic effects of the dual CK1δ/ε inhibitor, PF670462, support CK1δ/ε as novel therapeutic targets for IPF.