CTHRC1: An Emerging Biomarker in Lung Fibrosis

Pulmonary fibrosis is a chronic, progressive, and irreversible lung disease characterized by fibrotic scarring in the lung parenchyma. This condition involves the excessive accumulation of extracellular matrix (EM) due to a persistently activated wound-repair response. The aberrant activation of myofibroblasts in the alveolar environment by Transforming Growth Factor beta (TGF-β) and other signaling molecules is considered a key event in the development and progression of fibrosis. A primary target of TGF-β signaling in fibrosis is Collagen Triple Helix Repeat Containing 1 (CTHRC1), a secreted glycoprotein that plays a pivotal role in extracellular matrix deposition. CTHRC1 is transcriptionally regulated by TGF-β and inhibits both TGF-β and canonical Wnt signaling pathways. This dual function suggests that CTHRC1 is vital in regulating tissue remodeling during wound repair. In this review, we will highlight recent studies suggesting that CTHRC1 can serve as a diagnostic and prognostic biomarker for fibrosis in idiopathic pulmonary fibrosis, rheumatoid arthritis-interstitial lung disease, systemic sclerosis, and post-COVID lung fibrosis. Notably, the expression of CTHRC1 is responsive to antifibrotic drugs such as pirfenidone indicating its potential as a therapeutic target. Collectively, these findings suggest that CTHRC1 may present new opportunities for the diagnosis, stratification, and treatment of patients with lung fibrosis.