Myofibroblast differentiation in idiopathic pulmonary fibrosis: epigenetic mechanisms and therapeutic targeting by cAMP

Idiopathic pulmonary fibrosis (IPF) is a progressive and devastating lung disorder characterised by irreversible scarring of the lung. IPF affects over 8,000 people in the UK. It causes disabling breathlessness, and often leads to death within a few years. The cause of the disease is unknown despite much research and there is no effective therapy to stop or slow the disease progression. Myofibroblasts (a cell type) are the major cells responsible for the scar formation (fibrosis) and can be transformed from fibroblasts and epithelial cells (two other cell types) by the potent pro-fibrotic mediator termed transforming growth factor beta1 (TGFbeta1). Under normal conditions, the formation of myofibroblasts is inhibited by a potent antifibrotic mediator termed prostaglandin E2 (PGE2). However, during the process of myofibroblast formation, the cells gradually lose the capability to produce this mediator, resulting in excessive fibroblast growth and scar formation. Our preliminary studies suggest that exogenously supplied PGE2 and related drugs can inhibit and, to some extent, reverse the TGFbeta1-induced transformation from normal lung fibroblasts and epithelial cells to myofibroblasts, thus could stop the excessive scar formation and be beneficial for patients with IPF as novel therapies. In the studies proposed here we will use normal lung fibroblasts and epithelial cells to study the mechanisms of TGFbeta1-induced transformation to myofibroblasts and the effect of exogenous PGE2 and related drugs on the transformation and to determine the molecular mechanisms of action of these drugs. In addition, we will also use lung tissues from patients with IPF and a mouse model of pulmonary fibrosis to confirm the findings with cell studies. We believe that the outcome of our studies will improve our understanding of the pathogenesis of IPF and provide preclinical evidence for PGE2 and related drugs as potential novel therapies to benefit IPF patients in the near future.

Idiopathic pulmonary fibrosis (IPF) is a deadly respiratory disease of unknown aetiology with no effective therapy. IPF is characterised by fibroblast accumulation and activation and excessive collagen deposition, leading to distortion of the alveolar architecture, progressive loss of lung function, and ultimately death. Myofibroblasts are the primary effector cells in IPF and can be differentiated from lung fibroblasts and epithelial cells. PGE2, a major prostanoid generated by cyclooxygenase-2 (COX-2) from lung fibroblasts and epithelial cells, inhibits myofibroblast differentiation through cAMP. However, PGE2 is reduced due to COX-2 repression in this process, leading to unopposed myofibroblast differentiation. Increasing evidence suggests that epigenetic regulation plays a key role in myofibroblast differentiation and that cAMP elevating agents can compensate for exogenous PGE2 loss to prevent and even reverse myofibroblast differentiation.
We hypothesize that lung fibroblasts and epithelial cells are epigenetically reprogramed during their differentiation to myofibroblasts in IPF, resulting in gene specific epigenetic modifications relative to the expression and repression key genes and that cAMP elevating agents can prevent, even reverse, the differentiation at least partly through epigenetic regulation. We aim to elucidate the epigenetic mechanisms and cAMP-mediated inhibition of myofibroblast differentiation by studying TGF-beta1-induced fibroblast-to-myofibrobalst differentiation and epithelial-mesenchymal transition in vitro, validating key epigenetic findings relative to gene expression in IPF lung tissue and in a mouse model of pulmonary fibrosis, and evaluating the anti-fibrotic effect of cAMP elevating agents and epigenetic inhibitors in the mouse model. The outcome of this project will improve our understanding of IPF pathogenesis and provide preclinical evidence for these agents as potential novel therapies to benefit IPF patients.

In addition to the academic beneficiaries described separately, this research has the potential to benefit a wide group of people. The group of people that are most likely to benefit will be patients with idiopathic pulmonary fibrosis (IPF). IPF is a chronic fatal lung disease of unknown aetiology and with no effective treatment and a median survival of 2.4 years. This study aims to develop novel therapeutic strategies based on a better understanding of IPF pathogenesis. Successful delivery of this study will not only improve the understanding of IPF pathogenesis but also provide pre-clinical evidence for cAMP elevating agents and epigenetic inhibitors as potential new therapies for IPF patients. The drugs we plan to test are the PDE4 inhibitors roflumilast and the HDAC inhibitor LBH589, which are in clinical use for COPD and cancer treatment, respectively, but their use in IPF treatment has not been tested. We have preliminary evidence that the drugs have potent anti-fibrotic effect from in vitro studies and we are going to test their effect in a murine model of pulmonary fibrosis. Positive results can soon be translated into clinical trial either locally through the Nottingham Respiratory Research Unit or by clinicians in the UK and abroad. There are approximately 5000 new cases of IPF in the UK each year, which represents a huge burden for NHS. There is a realistic prospect that our results can lead to new therapies to improve the quality of life of IPF patients and reduce the cost of caring, and thus will have a big positive impact on the nation's health and wealth.
The public sector will benefit through the development of new scientific knowledge, and the enhancement of the research experience and skills of the researchers involved. The post-doctoral research fellows working on the project will also develop research and professional skills, such as writing, inter-people communication and presentation, which they can apply in both academic and non-academic sectors.
Results from the research, particularly the drug effect, will likely to attract the interest and investment of pharmaceutical companies to redesign and test more effective and less toxic drugs for IPF treatment, which in turn will benefit them for their research knowledge and skills and product output in the long run and benefit the economy of the country.