Stretching of fetal membranes increases the concentration of interleukin-8 and collagenase activity

Byline: Emad El Maradny, Naohiro Kanayama, Abdul Halim, Kayoko Maehara, Toshihiko Terao Keywords: Amnion; amniochorion; interleukin-8; collagenase activity; stretching; muscles of lower uterine segment Abstract: OBJECTIVE: The aim of this study was to determine whether stretching of fetal membranes can increase interleukin-8 concentration and collagenase activity. STUDY DESIGN: Strips of whole fetal membranes, amnion, or muscles of the lower uterine segment were stretched for 2 or 4 hours. Interleukin-8 and collagenase activity were measured in homogenized control and stretched samples. Immunohistochemical staining for interleukin-8 was carried out. RESULTS: The interleukin-8 concentration increased significantly after the whole fetal membranes were stretched for 2 and 4 hours (p < 0.0007 and 0.001, respectively). Also, stretching of amnion and muscles of the lower uterine segment for 2 and 4 hours increased the concentration of interleukin-8 significantly (p < 0 .0007 after 2 and 4 hours, respectively). Collagenase activity was significantly increased after stretching of amnion, amniochorion, and muscles of the lower uterine segment for 4 hours (p < 0.0007, 0.006, and 0.0007, respectively). After stretching, samples were darkly stained for interleukin-8 compared with control nonstretched samples. CONCLUSION: Stretching of amnion, amniochorion, and muscles of the lower uterine segment increased interleukin-8 production and collagenase activity. (Am J Obstet Gynecol 1996;174:843-9.) Author Affiliation: Hamamatsu, Japan Article History: Received 18 April 1995; Revised 1 August 1995; Accepted 11 August 1995 Article Note: (footnote) [star] From the Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine., [star][star] Reprint requests: Emad El Maradny, Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, 3600 Handa-cho, 431-31 Hamamatsu, Japan., a 0002-9378/96 $5.00 + 0 6/1/68535