Reversing Bleomycin-Induced Lung Fibrosis through targeted MicroRNA inhibition: An ATII-driven therapeutical Approach for Alveolar Repair in IPF

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease of unknown origin and median survival of 3 years from diagnosis. Hypoxia and aging hinder physiological alveolar repair mechanisms after injury such as ATII to ATI trans-differentiation. We aim to investigate the roles of aging and microRNAs in IPF and their potential as therapeutic targets to develop ATII-driven lung regenerative therapies. We conducted a high-content screening assay on 2042 human microRNA mimics using primary murine ATII cells, focusing on miRNAs inhibiting ATII to ATI trans-differentiation by promoting cellular senescence. We identified two microRNAs, expressed by ATII cells and lung fibroblasts, with increase levels upon bleomycin injection. This overexpression impedes ATII-to-ATI trans-differentiation and drives paracrine profibrotic effects, including fibroblast-to-myofibroblast transition. Myofibroblasts, which exhibit high levels of selected microRNAs, secrete factors that inhibit ATII to ATI trans-differentiation, suggesting that these two microRNAs sustain a disease-promoting network between ATII cells and fibroblasts. We demonstrated that the intra-tracheal administration of LNA-anti-miRNA molecules reduce lung fibrosis in both aged (20 months) and young mice. Therapeutic agents were administered at 10 days and 21 days after bleomycin administration. The treatment resolve lung fibrosis, increase number of alveoli and reduce number of KRT8+ cells. We aim to identify targets of selected microRNAs and uncovering key pro-fibrotic factors secreted by epithelial cells overexpressing miRNAs to develop new anti-fibrotic and pro-regenerative therapies.