Metabolic Reprogramming as a Driver of Fibroblast Activation in PulmonaryFibrosis

Pulmonary fibrosis refers to a heterogeneous group of disorders that scar the lung, most often irreversibly. To date, there are limited effective treatments for these conditions, despite decades of research in this area of investigation. In pulmonary fibrosis, the principle cell responsible for producing the vast majority of scar tissue is the fibroblast, making these cells ideally suited for drug targeting. For decades, the major experimental approach to blocking the activity of lung fibroblasts has been either to inhibit the interaction of fibroblast growth factors with their receptors or interfere with downstream effector molecules regulating extracellular matrix production. However, emerging evidence now indicates that lung fibroblasts also undergo dramatic metabolic reprogramming in the setting of growth factor stimulation. These discoveries, along with preclinical investigations showing marked reductions in lung fibrosis after targeting specific metabolic pathways, has led to a total rethinking of drug development in the pulmonary fibrosis field. Here, we review the major metabolic pathways and highlight some of the key metabolic events that occur in the transition of fibroblasts from quiescent to activated states. Moreover, we discuss the emerging evidence linking changes in fibroblast metabolism to pulmonary fibrosis and propose how targeting specific metabolic pathways could be employed in the treatment of fibrotic lung diseases.