Nerandomilast is Associated With Altered Alveolar Epithelial Cell State Dynamics While Attenuating Fibrotic Remodeling in Pulmonary Fibrosis

Pulmonary fibrosis is a progressive and life-threatening lung disorder characterized by excessive fibrogenesis and impaired respiratory function. Nerandomilast, a preferential phosphodiesterase 4B inhibitor, is currently approved for the treatment of idiopathic pulmonary fibrosis and progressive pulmonary fibrosis in several countries following its demonstrated clinical efficacy in Phase III trials. However, its cellular mechanisms of action remain incompletely understood. In this study, we investigated the effects of nerandomilast on a bleomycin-induced mouse model of lung fibrosis. Nerandomilast treatment attenuates fibrotic remodeling and preserves alveolar epithelial architecture. Single-cell transcriptomic analyses revealed altered alveolar epithelial cell state dynamics accompanied by increased cell cycle-associated pathways in alveolar type 2 cells and an increased relative abundance of alveolar type 2 cells. Consistent with the single-cell findings, nerandomilast was associated with an increased SFTPC-positive area and the preservation of alveolar epithelial architecture in vivo. Collectively, our findings suggest that nerandomilast attenuates fibrotic remodeling while modulating alveolar epithelial cell state dynamics, which may provide a possible cellular explanation for its clinical efficacy in patients with pulmonary fibrosis.