In fibrotic lung fibroblasts, basal levels of p53 protein (and miR-34a) are markedly suppressed, leading to reduced p53-mediated inhibition of uPA and uPAR, or concurrent induction of PAI-1. These changes contribute to excessive FL-fibroblast proliferation and production of extracellular matrix (ECM), and, therefore, pulmonary fibrosis. These processes are reversed by treating the cells, and treating subjects suffering from idiopathic pulmonary fibrosis (IPF) with the small organic molecule nutlin-3a (NTL) or with a peptide, CSP-4 (SEQ ID NO:1), or variants or derivatives or multimers of this peptide, which increase p53 levels by inhibiting MDM2-mediated degradation of p53 protein. Use of these compounds serves as a new approach to the treatment of IPF, they restore p53 expression and p53-mediated changes in the uPA-fibrinolytic system in FL-fibroblasts and restrict production and deposition of ECM.
