Pengxiu Cao ^1* Hong-Long (James) Ji ^2* Jianwei Sun ^3*

• ¹ Hebei Normal University, Shijiazhuang, China
• ² Loyola University Chicago, Chicago, Illinois, United States
• ³ Yunnan University, Kunming, Yunnan Province, China

Pulmonary fibrosis (PF) is a complex and highly heterogeneous disease characterized by the accumulation of stiffened extracellular matrix in lung tissue, the replacement of normal lung tissue with fibrotic tissue, and the progressive loss of lung function. PF is induced by genetic, environmental, and inflammatory factors and is associated with metabolic disorders. Extracellular bioactive mediators, such as endocrine factors and metabolites, play critical roles in the progression of PF. For instance, iron promotes PF by activating fibroblasts (1). Animal models have also demonstrated that thyroid hormone, brain-derived neurotrophic factor, and atrial natriuretic peptide regulate PF (2)(3)(4). Focusing treatment on dysregulated endocrine factors rather than inhibiting downstream fibrosis markers may be more effective. In addition, supplementing endogenous cytokines or metabolites theoretically results in fewer side effects than exogenous drugs. This research topic, "Pulmonary Fibrosis and Endocrine Factors", aims to define the endogenous factors associated with pulmonary fibrosis in order to facilitate the discovery of novel and effective therapeutic strategies with fewer side effects. This collection addresses the roles of lipid metabolism, glucose metabolism, complement pathway, and serum biomarkers in PF or cystic fibrosis (CF). It also investigates the association of vitamin D metabolism-related single nucleotide polymorphisms with the risk of chronic obstructive pulmonary disease (COPD).