Abstract
BACKGROUND AND AIMS: Juvenile polyps are the most common type of pediatric gastrointestinal polyp and are typically characterized as hamartomatous overgrowths. Juvenile polyps are highly vascularized tissues and display a markedly increased mucosal microcirculation. Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes that play an essential role in the physiological degradation of the extracellular matrix in normal development, tumor invasion, and metastasis, as well as angiogenesis. We hypothesized that the presence of these enzymes in urine may serve as clinical biomarkers of juvenile polyps. PATIENTS AND METHODS: In this preliminary study, we analyzed 32 urine samples collected prospectively from 16 subjects with known or suspected juvenile polyps who presented to the endoscopy unit for colonoscopic evaluation and 16 age- and sex-matched controls. Urinary MMPs were analyzed by zymography and their localized tissue expression was assayed via immunohistochemistry of tissue sections. RESULTS: MMPs were detected in the urine of patients with juvenile polyps with significantly higher frequency when compared with urine of control subjects. In addition, immunohistochemistry demonstrated that high levels of MMPs were localized in the epithelium and lamina propria of polyp tissue when compared with colonic tissue collected from healthy control subjects. CONCLUSIONS: These data are the first to demonstrate that MMPs are present in the urine and tissue of patients with juvenile polyps, and these enzymes have the potential to serve as surrogate markers for the presence of polyps.