Idiopathic pulmonary fibrosis (IPF) is associated with downregulation of cyclooxigenase 2 (COX-2) expression and low levels of the antifibrotic prostaglandine E2. On the other hand, myofibroblasts play a pivotal role in fibrosis development. Local fibroblasts and epithelial cells are potential sources of myofibroblasts.

Aim: 

To study COX-2 expression and PGE2 secretion in myofibroblast, in fibroblast-myofibroblast transition and Epithelial Mesenchimal Transition (EMT) induced by transforming growth factor b1 (TGF- b1)

Methods: 

Normal and fibrotic primary lung fibroblast were obtained from subjects with pneumothorax (n=5) and from patiens with IPF (n=5) respectively. Epitelial cell line A549 was also used for studying EMT. Inmunofluorescence against COX-2 and/or a-SMA were performed. COX-2 and a-SMA was also analysed by western blot and secreted PGE₂ was measured by ELISA. Nuclear incorporation of a nucleoside analog was detected for measuring cell proliferation.

Results: 

Basally, IPF fibroblast showed higher levels of aSMA compared with control fibroblasts but both exhibited undetectable COX-2 expression. After Interleukin 1b (Il-1b) stimulation (10 ng/ml), control fibroblasts presented higher COX-2 levels than fibrotic fibroblasts. Coimmunofluorescense in IL-1b stimulated fibroblasts, revealed myofibroblasts with reduced COX-2 expression. Fibroblasts treated with TGF-b1 expressed a-SMA in a dosis and time dependent manner both in IPF and control fibroblasts. A549 treated with TGF-b1 changed their morphology expressing stress fibers related with EMT. Myofibroblasts obtained from treating fibroblasts or A549 with TGF-b1 showed dramatic low COX-2 levels in response to IL-1b stimulation. Furthermore, PGE-2 secretion was also abrogated. These effects were no related with cell proliferation.

Conclusion: 

Our results demonstrate that myofibroblast phenotype is characterized by an altered COX-2 and PGE-2 expression in response to IL-1b. These alterations could represent an important mechanism in remodeling processes involving myofibroblast implication.