Caffeine modulates glucocorticoid-induced expression of CTGF in lung epithelial cells and fibroblasts

Abstract

BackgroundAlthough caffeine and glucocorticoids are frequently used to treat chronic lung disease in preterm neonates, potential interactions are largely unknown. While anti-inflammatory effects of glucocorticoids are well defined, their impact on airway remodeling is less characterized. Caffeine has been ascribed to positive effects on airway inflammation as well as remodeling. Connective tissue growth factor (CTGF, CCN2) plays a key role in airway remodeling and has been implicated in the pathogenesis of chronic lung diseases such as bronchopulmonary dysplasia (BPD) in preterm infants. The current study addressed the impact of glucocorticoids on the regulation of CTGF in the presence of caffeine using human lung epithelial and fibroblast cells.MethodsThe human airway epithelial cell line H441 and the fetal lung fibroblast strain IMR-90 were exposed to different glucocorticoids (dexamethasone, budesonide, betamethasone, prednisolone, hydrocortisone) and caffeine. mRNA and protein expression of CTGF, TGF-β1-3, and TNF-α were determined by means of quantitative real-time PCR and immunoblotting. H441 cells were additionally treated with cAMP, the adenylyl cyclase activator forskolin, and the selective phosphodiesterase (PDE)-4 inhibitor cilomilast to mimic caffeine-mediated PDE inhibition.ResultsTreatment with different glucocorticoids (1 μM) significantly increased CTGF mRNA levels in H441 (p < 0.0001) and IMR-90 cells (p < 0.01). Upon simultaneous exposure to caffeine (10 mM), both glucocorticoid-induced mRNA and protein expression were significantly reduced in IMR-90 cells (p < 0.0001). Of note, 24 h exposure to caffeine alone significantly suppressed basal expression of CTGF mRNA and protein in IMR-90 cells. Caffeine-induced reduction of CTGF mRNA expression seemed to be independent of cAMP levels, adenylyl cyclase activation, or PDE-4 inhibition. While dexamethasone or caffeine treatment did not affect TGF-β1 mRNA in H441 cells, increased expression of TGF-β2 and TGF-β3 mRNA was detected upon exposure to dexamethasone or dexamethasone and caffeine, respectively. Moreover, caffeine increased TNF-α mRNA in H441 cells (6.5 ± 2.2-fold, p < 0.05) which has been described as potent inhibitor of CTGF expression.ConclusionsIn addition to well-known anti-inflammatory features, glucocorticoids may have adverse effects on long-term remodeling by TGF-β1-independent induction of CTGF in lung cells. Simultaneous treatment with caffeine may attenuate glucocorticoid-induced expression of CTGF, thereby promoting restoration of lung homeostasis.

Increase in CTGF mRNA expression by respiratory syncytial virus infection is abrogated by caffeine in lung epithelial cells

“…According to our observations in H441 cells, the simultaneous presence of glucocorticoids and RSV infection might provoke aggravated remodeling processes in the lower airways via increase in CTGF expression, which has been demonstrated in bleomycin‐induced fibrosis . Furthermore, in addition to the prevention of glucocorticoid‐mediated increase, our data suggest that caffeine treatment is able to block RSV—as well as dexamethasone/RSV‐caused upregulation of CTGF mRNA expression. Apart from its preventive effects on the development of BPD, caffeine might thus also counteract potential pro‐fibrotic effects mediated by RSV.…”

“…We report an upregulation of CTGF mRNA by RSV infection in H441 lung epithelial cells which was additive to the recently described induction by glucocorticoids . Different to work describing a reduction of vanadium pentoxide‐induced fibrosis by RSV via reduction of growth factors, our data indicate that RSV infection might conceivably be able to induce fibrotic conditions by increasing CTGF mRNA in lung epithelial cells which might be further enhanced by glucocorticoids …”

“…We recently described increase in CTGF expression by various glucocorticoids in lung epithelial and fibroblast models . In addition, we have shown that TGF‐β1‐induced upregulation of CTGF can be antagonized by caffeine in A549 lung epithelial cells .…”

“…NCI‐H441 (H441) and IMR‐90 cells were purchased from ATCC (LGC Standards, Teddington, UK) and cultured as described . Recombinant green fluorescent protein‐expressing RSV (rgRSV) was a kind gift of Peter L. Collins (National Institute of Allergy, Immunology, and Infectious Diseases, National Institutes of Health, Bethesda, MD).…”

“…RNA extraction, RT‐PCR, and qPCR were performed as described previously . Levels of mRNAs were normalized to those of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH).…”