Matrilysin (matrix metalloproteinase 7) in parturition, premature rupture of membranes, and intrauterine infection

OBJECTIVE: Matrix metalloproteinases are enzymes capable of degrading extracellular matrix components. Matrilysin (matrix metalloproteinase 7), a novel member of this family, degrades fibronectin and proteoglycans. The objective of this study was to determine whether parturition (either term or preterm), premature rupture of the membranes, and microbial invasion of the amniotic cavity are associated with changes in the amniotic fluid concentration of matrilysin. STUDY DESIGN: A cross-sectional study was conducted with 275 women in the following categories: (1) second trimester, (2) term not in labor, (3) term in labor, (4) term with microbial invasion of the amniotic cavity, (5) preterm labor with intact membranes without microbial invasion of the amniotic cavity who delivered at term, (6) preterm labor without microbial invasion of the amniotic cavity who delivered preterm, (7) preterm labor with microbial invasion of the amniotic cavity, (8) preterm premature rupture of membranes with and without microbial invasion of the amniotic cavity, and (9) term premature rupture of membranes not in labor and without microbial invasion of the amniotic cavity. Matrilysin concentrations were measured with a sensitive specific immunoassay that was validated for amniotic fluid. RESULTS: Matrilysin was detectable in 97.4% (268/275) of the samples. The concentration of matrilysin increased with advancing gestational age (r = 0.8; P < .001). Parturition at term was not associated with a significant increase in amniotic fluid concentration of matrilysin. Preterm parturition in the absence of microbial invasion of the amniotic cavity was associated with a significant increase in amniotic fluid concentration of matrilysin (preterm labor with preterm delivery: median, 1.7 ng/mL; range, 0.45-21.6 mg/mL; vs preterm labor with term delivery: median, 1,2 ng/mL; range, 0.17-42.1 ng/mL; P < .05). Premature rupture of membranes without microbial invasion of the amniotic cavity (either term or preterm) was not associated with a significant change in the amniotic fluid matrilysin concentration. Intra-amniotic infection was associated with a significant increase in amniotic fluid matrilysin among both patients with preterm labor and patients with preterm premature rupture of membranes (preterm labor with microbial invasion of the amniotic cavity: median, 3.2 ng/mL; range, 0.16-21.9 ng/mL; vs preterm labor and delivery without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.45-21.6 ng/mL; vs preterm labor with term delivery: median, 1.2 ng/mL; range, 0.17-42.1 ng/mL; P < .01 for each comparison; and preterm premature rupture of membranes without microbial invasion of the amniotic cavity: median, 1.7 ng/mL; range, 0.29-13.9 ng/mL; vs preterm premature rupture of membranes with microbial invasion of the amniotic cavity: median, 3.6 ng/mL; range, 0.59-20.3 nl/mL; P < .01). CONCLUSION: Matrilysin is a physiologic constituent of amniotic fluid, and its concentration increases with advancing gestational age. Microbial invasion of the amniotic cavity in preterm gestations was associated with a significant increase in amniotic fluid concentration of matrilysin. Matrilysin therefore may play a role in the host defense mechanism.