CSP7 Protects Alveolar Epithelial Cells by Targeting p53-Fibrinolytic Pathways During Lung Injuries.

Area of Science:

• Pulmonary Medicine
• Cell Biology
• Genetics

Background:

• Idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) feature impaired alveolar epithelial regeneration.
• Telomere dysfunction in type II alveolar epithelial cells (A2Cs) is a key factor in these diseases.
• Aging, genetic factors, and toxicant exposures like tobacco smoke (TS) exacerbate telomere dysfunction.

Purpose of the Study:

• To investigate if CSP7 improves telomere function in A2Cs.
• To assess CSP7's protective effects against senescence and apoptosis in bleomycin (BLM)-induced pulmonary fibrosis (PF) and chronic TS exposure models.
• To elucidate the molecular pathways involved in CSP7-mediated protection.

Main Methods:

• Isolated A2Cs from IPF/COPD patients and BLM/TS-exposed mouse models.
• Analyzed telomere length, p53, caspase-3, beta-galactosidase, SIAH-1, TRF1, TRF2, and TERT expression.
• Treated wild-type mice with CSP7 in BLM and TS models.
• Utilized PAI-1 and uPA mouse models, and microRNA-34a knockout models.

Main Results:

• A2Cs from IPF/COPD patients and fibrotic mice showed telomere shortening, increased p53, caspase-3, beta-galactosidase, SIAH-1, TRF1, and decreased TRF2, TERT.
• CSP7 treatment reversed these changes in wild-type mice exposed to BLM or TS.
• PAI-1 deficiency or microRNA-34a loss in A2Cs conferred resistance to telomere dysfunction.

Conclusions:

• Telomere dysfunction in A2Cs, involving p53, SIAH-1, and TRF2/TERT pathways, contributes to lung fibrosis and injury.
• CSP7 demonstrates therapeutic potential by restoring telomere function and protecting A2Cs.
• The p53-microRNA-34a and p53-uPA pathways are implicated in telomere dysfunction.