title: Alpha-lipoic acid inhibits thrombin-induced fetal membrane weakening in vitro.
abstract: Cytokine-mediated inflammation and abruption-induced thrombin generation are separately implicated in matrix metalloproteinase (MMP)-mediated weakening of fetal membranes (FM) leading to preterm premature rupture of the fetal membranes (PPROM). At term, FM of both labored vaginal and unlabored Cesarean deliveries exhibit a weak zone overlying the cervix exhibiting ECM remodeling characterized by increased MMP9 protein and activity. We have reproduced these biochemical changes as well as FM weakening in vitro using tumor necrosis factor-alpha (TNF) and interleukin (IL)-1β, inflammatory cytokines implicated in PPROM. Additionally, we have reported that the antioxidant and NFκB inhibitor alpha-lipoic Acid (LA) blocks these TNF-induced effects. We now present the first direct evidence that thrombin also can induce FM weakening in vitro, and LA treatment inhibits this thrombin-induced-weakening. Full thickness FM fragments from unlabored Cesarean deliveries were incubated with increasing doses of thrombin (0-100 u/ml) for 48 h. Fragments were then strength tested (breaking force and work to rupture) using our published methodology. MMP3 and 9 levels in tissue extracts were determined by Western blot and densitometry. To determine the effect of LA, FM fragments were incubated with control medium or 10 u/ml thrombin, with or without 0.25 mM LA. Strength testing and MMP induction were determined. Thrombin induced a dose-dependent decrease in FM strength (42% baseline rupture force and 45% work to rupture) coupled with a dose-dependent increase in MMP3 and 9 expression (all p < 0.001). Treatment of FM with 0.25 mM LA completely inhibited thrombin-induced FM weakening and MMP expression (all p < 0.001). Thrombin treatment of cultured FM induces mechanical weakening and increased MMP3 and 9. Treatment of FM with LA inhibits these thrombin-induced effects. We speculate LA may prove clinically useful in prevention of PPROM associated with abruption.
authors: Departments of Pediatrics, Case Western Reserve University, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH, USA.
authors: R M
authors: RM
authors: Moore
authors: F
authors: F
authors: Schatz
authors: D
authors: D
authors: Kumar
authors: B M
authors: BM
authors: Mercer
authors: A
authors: A
authors: Abdelrahim
authors: N
authors: N
authors: Rangaswamy
authors: C
authors: C
authors: Bartel
authors: J M
authors: JM
authors: Mansour
authors: C J
authors: CJ
authors: Lockwood
authors: J J
authors: JJ
authors: Moore
mesh_terms: D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D005321:Extraembryonic Membranes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000378:metabolism*; D006801:Humans; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D011247:Pregnancy; D008063:Thioctic Acid / Q000494:pharmacology*; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000494:pharmacology / Q000502:physiology; D046509:Tissue Culture Techniques
chemical_list: D008063:Thioctic Acid; D013917:Thrombin; C511768:MMP3 protein, human; D019278:Matrix Metalloproteinase 3; D020780:Matrix Metalloproteinase 9