Progressive apoptosis in chorion laeve trophoblast cells of human fetal membrane tissues during in vitro incubation is suppressed by antioxidative reagents

Abstract

Previously, we demonstrated apoptotic cell death in the chorion laeve trophoblast layer of human fetal membrane tissues during the late stages of pregnancy, the progression of apoptosis during incubation in vitro, and its suppression by a low concentration of glucocorticoid hormones. We now report examination of mRNA expression of inflammatory cytokines [interleukin (IL)-1β, IL-6, tumor necrosis factor-α] and antioxidative enzyme genes [heme oxygenase 1, catalase, Mn-superoxide dismutase (SOD), Cu/Zn-SOD, glutathione S-transferase, glutathione reductase and glutathione peroxidase] and apoptosis-related genes during in vitro progression of apoptosis with or without glucocorticoid by a reverse transcription/PCR method. It was shown that the mRNA levels increased in chorion laeve tissue for each cytokine examined and for catalase, heme oxygenase 1 and Mn-SOD in direct correlation with the in vitro incubation period. By Western blotting the existence of Mn-SOD protein, and its slight increase with incubation time, was also shown. The investigation of the influence of antioxidative reagents [pyrrolidine dithiocarbamate (PDTC), N-acetyl-L-cysteine (NAC) and nordihydro-guaiaretic acid (NDGA)] on DNA fragmentation showed that DNA fragmentation in chorion laeve tissues was inhibited by ≈ 50% in the presence of 1 mM PDTC, 30 mM NAC and 1 mM NDGA. These results suggest that apoptotic cell death of the trophoblast layer of chorion tissues may be induced through intracellular oxidative stress at the stage of parturition.