Amniochorion gelatinase-gelatinase inhibitor imbalance in vitro: a possible infectious pathway to rupture.
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 x 10(6) and 366 transcripts of gelatinase A and B, respectively, compared with only 5.9 x 10(4) (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 x 10(5) transcripts of tissue inhibitor of metalloproteinase 2, whereas lipopolysaccharide stimulation produced 4.1 x 10(5) 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.


CONCLUSIONS
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.
Fortunato
S J
SJ
Maternal Fetal Group and Perinatal Research Center of the Women's Health Research and Education Foundation and Aquinas College, Nashville, Tennessee 37203, USA. fortunat@edge.net
Menon
R
R
Lombardi
S J
SJ
D000650:Amnion / Q000201:enzymology*; D002823:Chorion / Q000201:enzymology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000201:enzymology / Q000209:etiology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D020778:Matrix Metalloproteinase 2 / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D061965:Matrix Metalloproteinase Inhibitors; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000201:enzymology*; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation
D008070:Lipopolysaccharides; D061965:Matrix Metalloproteinase Inhibitors; D012333:RNA, Messenger; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9