Effect of Interleukin-8 on Human Trophoblast Invasion

Abstract

Objective: We have previously shown that interleukin-8 (IL-8) expression and production is increased throughout the implantation window and afterwards in human endometrium. IL-8 production is significantly higher on the surface epithelium and glandular cells than stroma, which suggests a possible role in implantation and early placentation. In this study, we investigated the role of IL-8 on trophoblast invasion in a cell culture system. Materials and Methods: Human cytotrophoblasts were isolated from placentas by enzymatic digestion (trypsin-DNase) and followed by separation in a discontinuous Percoll gradient. Cells suspended in DMEM-HG containing 10% fetal bovine serum were initially labeled with Calcein-AM. Labeled cells were plated on 8 μm porous fluoroblock membrane inserts. The amount of invasion was quantified by fluorescence underneath the membrane. In a separate experiment cytotrophoblasts (5×105/well) were cultured in six well plates for 24 h and treated with IL-8 (1 ng/ml) the next day. Conditioned media were collected 24 h later and analyzed with a soluble assay of metalloproteinase activity based on spectrophotometry and was characterized by substrate gel zymography. Results: IL-8 treatment induced a 1.8-fold increase in the cytotrophoblast invasion of the matrigel matrix. IL-8 also increased 2-fold the collagenolytic activity of cytotrophoblasts. This increased activity was primarily due to MMP-9 that produced clear bands in zymograms at 92 kD. Conclusions: IL-8 may play an important regulatory role in trophoblast invasion by increasing their MMP-9 activity.