Amniochorion Gelatinase-Gelatinase Inhibitor Imbalance In Vitro

Abstract

In Brief Objective To estimate the effect of lipopolysaccharide on gelatinases and tissue inhibitors of matrix metalloproteinase 2 (gelatinase inhibitor) balance in human fetal membranes. Methods Amniochorionic membranes in organ explant were stimulated with 1000 ng/mL lipopolysaccharide for 24 hours after a 48-hour preincubation period. Quantitative competitive polymerase chain reaction (PCR) was done to quantitate messenger RNAs for gelatinase A and B (matrix metalloproteinase 2 and 9) and tissue inhibitor of metalloproteinase 2. Protein levels were assayed by enzyme-linked immunosorbant assay. The molar ratio between gelatinases and tissue inhibitor of metalloproteinase 2 was calculated. Statistical evaluation was done by Mann-Whitney U test. Results Lipopolysaccharide stimulation produced 3.6 × 106 and 366 transcripts of gelatinase A and B, respectively, compared with only 5.9 × 104 (P = .009) and three transcripts (P = .006), respectively, in the controls. Lipopolysaccharide stimulation released 210 ng/mL compared with 7 ng/mL of gelatinase A and B proteins compared with 120 (P = .01) and 4.6 ng/mL (P = .3) in controls, respectively. Control amniochorion produced 5.7 × 105 transcripts of tissue inhibitor of metalloproteinase 2, whereas lipopolysaccharide stimulation produced 4.1 × 105 transcripts (P = .69). Lipopolysaccharide reduced the release of this inhibitor from 114 ng/mL to 68 ng/mL (P = .007). The molar ratio between gelatinases and tissue inhibitor of metalloproteinase 2 increased from a balanced ratio of 1:1 to 3.1:1 after 1000 ng/mL of lipopolysaccharide. Conclusion Lipopolysaccharide increased the expression and release of gelatinases and decreased its inhibitor, which shifted the balance in favor of gelatinase activity leading to membrane degradation that predisposes to premature rupture of membranes. Lipopolysaccharide stimulation results in an imbalance in the molar ratio of gelatinases and tissue inhibitor of metalloproteinase 2 in human fetal membranes.