Introduction:  Progressive pulmonary fibrosis (PPF) is defined as an Interstitial Lung Disease (ILD), other than Idiopathic Pulmonary Fibrosis (IPF), with clinical, physiological and/ or radiological evidence of disease progression resembling IPF behavior. The matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of lung fibrosis and MMP-1 and MMP-7 have been suggested as an IPF diagnostic biomarker.

Aim and objectives: To investigate MMP-1 and MMP-7 in the identification of fibrotic non-IPF ILD patients at risk for PPF.

Methods: We measured MMP-1 and MMP-7 serum levels in 79 fibrotic non-IPF ILDs patients: 35 Connective Tissue Disorder-ILD, 23 Fibrotic Hypersensitivity Pneumonitis, 13 Sarcoidosis, 6 Nonspecific Interstitial Pneumonia and 2 Unclassified Fibrotic ILD. PPF was defined according with the ATS/ERS/JRS/ALAT Clinical Practice Guideline.

Results: The mean age was 62 years, 75.9% females. PPF criteria was met by 33 (41.7%) patients. MMP-7 (but not MMP-1) was significantly higher in the PPF group (p=0.01).  Using the binary logistic regression model MMP-7 was independently associated with PPF (OR=1.263; 95% CI 1.029?1.551, p=0.026), remaining significant after adjusting for sex, age and smoking history; the cutoff of 3.526 ng/mL presented a sensitivity of 61% and a specificity of 74% for PPF.

Conclusions: MMP-7 was significantly higher in the group of patients with PPF. This may be considered and further explored as a possible biomarker to identify those fibrotic ILDs patients at risk of PPF.