Role of serum matrix metalloproteinases-9 in pediatric cardiac patients with pneumonia

Background Matrix metalloproteinases-9 (MMP-9) is a member of a large group of zinc-dependent endopeptidases and is essential in immune response. It plays an imperative function in pneumonia pathogenesis. We aimed to evaluate the role of MMP-9 in pediatric patients with congenital heart diseases (CHD) who gained ventilator-acquired pneumonia. Patients and methods A total of 80 children were included, who were further divided into 30 cardiac patients with ventilator-associated pneumonia (VAP), 30 cardiac patients with pneumonias either hospital acquired or community acquired, and 20 age-matched and sex-matched cardiac patients without chest infection as the control group. Assessments of white blood cell count, neutrophil count, serum C-reactive protein (CRP), and MMP-9 were done in all studied children. Results Comparison among the studied groups regarding laboratory data revealed high significant difference regarding white blood cell, neutrophil count, CRP, and MMP-9, as they were elevated among cardiac children with VAP than other groups (P=0.0001, 0.0001, 0.0001, and 0.0001, respectively). There was no significant difference between cases with acyanotic CHD and those with cyanotic CHD either with increased pulmonary blood flow or with decreased pulmonary blood flow regarding MMP-9 (P=0.2446). Conclusion MMP-9 level was significantly elevated in cardiac patients with VAP than other groups. Serum MMP-9 was more elevated among cyanotic CHD with increased pulmonary blood flow as hypoxia can lead to increased expression of MMP-9. MMP-9 was correlated with other inflammatory markers, including CRP, neutrophils count, and white blood cells, which offers it as a marker in assessing severity of pediatric pneumonia in cardiac patients.