Objective: To investigate the effect of cyclooxygenase 2 (COX-2) and 15-prostaglandin dehydrogenase (15-PGDH) on preterm labor.
Methods: The expressions and localizations of COX-2 and 15-PGDH in placentas and fetal membranes were examined by immunohistochemical (IH) two-step assay (IH scores were expressed as the sum of the percentage of immunoreactivity and the stained degree of cells), respectively. The samples were obtained from 14 preterm delivery (PL), 18 term in labor (TL) and 17 term not in labor (control group).
Results: (1) The immunoreactivity of COX-2 was found in the amniotic epithelial cells, chorion cells and decidual cells. IH scores of COX-2 in amniotic epithelium of placenta or fetal membranes in PL were 4.6 +/- 1.2, 4.7 +/- 0.9, respectively; in TL were 3.2 +/- 1.0, 3.6 +/- 1.0, respectively, and in control group were 2.2 +/- 0.6, 2.5 +/- 0.9, respectively. IH scores in PL and TL were obviously higher than those in control group (P < 0.01). It was higher in PL than in TL (P < 0.01). The expression of COX-2 was not significantly different between amnion of placenta and amnion of fetal membranes among the three groups (P > 0.05). (2) IH scores of COX-2 in chorion of placenta in PL were 4.9 +/- 1.0, in TL were 3.9 +/- 1.2 and in control group were 2.3 +/- 0.7. IH scores in PL and TL were obviously higher than those in control group (P < 0.01), and it was higher in PL than in TL (P < 0.01). The expression of COX-2 was not significantly different among the three groups in chorion of fetal membranes (P > 0.05) and it was not significantly different among the three groups in decidual cell of placenta (P > 0.05), either. (3) The immunoreactivity of 15-PGDH was found in the amniotic epithelial cells, chorion cells and decidual cells. The expression of 15-PGDH was not significantly different among the three groups in amnion of placenta or fetal membranes (P > 0.05). IH scores of 15-PGDH in chorion of placenta and fetal membranes in PL were 1.5 +/- 0.6, 2.3 +/- 0.8, respectively, in TL were 2.6 +/- 0.8, 3.0 +/- 0.7, respectively, and in control group were 4.4 +/- 1.1, 4.1 +/- 1.2, respectively. IH scores in PL and TL were obviously lower than those in control group (P < 0.01), and it was lower in PL than in TL (P < 0.05). IH scores of 15-PGDH in decidua of placenta in PL were 2.1 +/- 0.7, in TL were 2.8 +/- 0.8 and in control group were 4.5 +/- 1.0. IH scores in PL and TL were obviously lower than those in control group (P < 0.01); it was lower in PL than in TL (P < 0.05).
Conclusions: The higher expression of COX-2 in amniotic epithelium and the lower expression of 15-PGDH in chorion and decidual cell are relevant with the onset of premature labor. They play a role in the pathogenesis of premature labor.