Targeting the Ubiquitin Proteasome System in Pulmonary Fibrosis
Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease characterized by chronic, progressive, fibrotic scarring of the lung leading to decline in lung function and ultimately death. The median survival is three to five years and the number of cases diagnosed each year is increasing. At present, only two drugs, nintedanib and pirfenidone, are available. Whilst these drugs slow progression of the disease, they do not improve overall survival and both exhibit side effect profiles that often lead to cessation of treatment. As such, there is an urgent need for new transformative therapies for this devastating disease. Although definitive understanding of the causative and initiating factors of IPF is still lacking, it is clear that a number of aberrant cellular processes are central to the pathogenesis of the disease. Disruption of the ubiquitin proteasome system has been linked to a number of pathways thought to drive IPF, including senescence, defective mitophagy and endoplasmic reticulum stress. In this chapter, we discuss these cellular events, and how targeting of E3 ligases and deubiquitinases, important components of the ubiquitin proteasome system, may be an attractive approach to treating IPF.