Inhibition of the de-ubiquitinse USP30 in human fibroblasts from IPF patients suppresses the fibrotic response

Pulmonary fibrosis is a serious medical problem. Treatment options are currently limited with a high unmet medical need for new therapeutic intervention strategies. A major aetiological driver is oxidative stress resulting from a failure to remove damaged mitochondria by mitophagy. A family of proteins regulating this process are the de-ubiquitinases which prevents mitophagy thereby maintaining a pro-fibrotic state. By inhibiting the de-ubiquitinase USP30 it is anticipated that this will improve mitochondrial function and halt the fibrotic response. Following informed consent, primary lung fibroblasts were isolated from peripheral lung biopsies taken from control subjects and patients with idiopathic pulmonary fibrosis. Immunohistochemistry was used to detect USP30 expression. An in vitro wound healing (scratch) assay was utilised to examine the impact of the USP30 inhibitor MTX112 in preventing fibrosis. Mitochondrial function as defined by reserve respiratory capacity was assessed using a Seahorse metabolic analyser. Increased expression of USP30 was detected in IPF lung tissue. The USP30 inhibitor MTX112 at 100nM significantly (p<0.01) slowed wound healing after both 24 and 48 hours by approximately 15% in IPF and 10% in control fibroblasts. MTX112 at 10 and 30nM significantly (p<0.05) improved mitochondrial function by 50% in IPF fibroblasts. Targeting USP30 may therefore be a novel therapeutic strategy for the treatment of pulmonary fibrosis by improving pulmonary fibroblast mitochondrial function and slowing tissue fibrosis, potentially halting disease progression.