Recent advances in pulmonary fibrosis: from lung surfactant to the immune connection

Pulmonary fibrosis (PF) encompasses a heterogeneous group of progressive interstitial lung diseases characterized by aberrant wound healing, extracellular matrix accumulation, and irreversible architectural remodeling of the lung. This review provides a comprehensive overview of the clinical spectrum, epidemiology, and genetic predisposition underlying PF, followed by an in-depth analysis of key molecular and cellular mechanisms driving fibrogenesis, including epithelial injury, dysregulated repair, profibrotic signaling pathways, and immune-mediated processes. Particular emphasis is placed on the role of lung surfactant dysfunction in fibrosis development, highlighting alterations in surfactant composition, metabolism, and associated genetic variants that contribute to epithelial stress and disease progression. The review also evaluates established and emerging circulating biomarkers, including serum proteins linked to epithelial damage, extracellular matrix remodeling, and immune activation, with attention to their diagnostic and prognostic utility. Finally, current and evolving therapeutic strategies are discussed in the context of progressive fibrosing phenotypes. Despite significant advances in understanding PF pathobiology, substantial gaps remain in early detection, disease stratification, and targeted treatment, underscoring the urgent need for improved translational approaches and precision medicine strategies.