Matrix metalloproteinases levels in induced sputum in IPF and CTD-ILD.

BACKGROUND

The involvement of matrix metalloproteinases (MMPs) in the pathogenesis of interstitial lung disease (ILD) is well-supported, and circulating MMP-7 has been validated as a biomarker. Nonetheless, there is a lack of understanding regarding the local MMPs.

METHODS

The consecutive cohort comprised 30 patients with idiopathic pulmonary fibrosis (IPF), 54 with connective tissue disease (CTD)-ILD, and 34 healthy subjects. Biomarker analysis of MMP-7, MMP-8, MMP-9, and pro-MMP-10 was conducted on both plasma and induced sputum (IS) samples. The correlation between IS MMP levels, pulmonary function, and sputum cell count in ILD patients was investigated.

RESULTS

Significantly greater concentrations of MMPs were found in individuals with ILD compared to healthy participants. These markers were more abundant in induced sputum than plasma, with both IPF and CTD-ILD patients showing a higher median elevation in IS levels than those in the control group. The detection rate pro-MMP-10 in IS was significantly higher than in plasma (80.47% vs. 6.25%). In CTD-ILD patients, IS MMP-7 positively correlated with RV/TLC, total cell counts, and neutrophils%. IS MMP-9 showed positive correlations with total cell counts and neutrophils%. In IPF patients, IS MMP-7 levels correlated with RV/TLC, while IS MMP-9 levels correlated with FVC% pred, TLC%, and total cell counts.

CONCLUSIONS

A notable increase of MMPs was observed in IS relative to plasma, correlated with inflammatory cells, lung function, and imaging features, implying that local MMPs evaluation could provide a more sensitive reflection of the pathophysiological changes in ILD.