Matrix Metalloproteinase 3: a Novel Effective Biomarker for Predicting the Mortality and the Severity of Pneumonia

Background: Matrix metalloproteinase 3 (MMP3) is known as an inflammatory factor; however, the effectiveness of MMP3 for diagnosis of pneumonia and predicting outcomes is unclear. We evaluated the diagnostic and prog-nostic value of serum MMP3 in patients with pneumonia. Methods: One hundred and eighty-five patients with pneumonia and 52 healthy controls were enrolled. Serum MMP3, neutrophil gelatinase-associated lipocalin (NGAL), interleukin 6 (IL-6), procalcitonin (PCT), and C -reac-tive protein (CRP) concentrations were measured at admission. The patients were followed up for 90 days. Results: Compared with healthy controls, the concentrations of MMP3, NGAL, and IL-6 at admission were signif-icantly higher in patients with pneumonia (p < 0.05). The median concentrations of MMP3, NGAL, and IL-6 were significantly higher in the patients with severe pneumonia than the group of non-severe pneumonia (p < 0.05). Compared with PCT (AUC = 0.778), CRP (AUC = 0.719), and IL-6 (AUC = 0.726), MMP3 (AUC = 0.846) and NGAL (AUC = 0.826) had significantly higher AUC values for distinguishing the severity of pneumonia. The ROC of the combination of MMP3, neutrophil to lymphocyte ratio (NLR), and D-dimer showed the best performance of predicting pneumonia severity, which gave an AUC of 0.956. The AUC of MMP3 (0.950) for predicting mortality was highest, followed by NLR (AUC = 0.945), D-dimer (AUC = 0.938), and NGAL (AUC = 0.913). Multivariable logistic regression analysis showed MMP3, D-dimer, and NLR were the independent predictors of hospital mor-tality in patients with pneumonia. Patients with MMP3 concentration > 124.3 ng/mL had a significantly higher risk of mortality (p < 0.05). Conclusions: MMP3 is a valuable biomarker in assessment of the severity and prediction of mortality in patients with pneumonia. (Clin. Lab. 2022;68:xx-xx. DOI: 10.7754/Clin.Lab.2021.210404)