Aim: Given the presence of the cytokinetic effects of Oncostatin M (OSM), we hypothesized that placental expression of OSM and serum OSM levels are elevated in preeclampsia. To verify this hypothesis, we determined the expression of OSM in placenta and levels of OSM in plasma form women with preeclampsia and normal pregnant women.
Methods: Sixteen women with severe preeclampsia and 16 normal pregnancy women were studied. Placental tissues were immediately frozen and stored at -80 degrees C until extraction of total RNA. Total RNA was extracted and real-time quantitative PCR was carried out. Placental tissues fixed in 4% paraformaldehyde were reacted with antibodies against OSM. An independent pathologist who was blind to the origins of the samples reviewed these stained slides. The maternal serum and umbilical venous concentration of OSM were determined by commercially available ELISA analysis.
Results: The mRNA expression level of OSM in preeclamptic placenta was increased by 3.91 times which was significantly higher than those of the normal group (P = 0.028). OSM immunoreactivity was significantly higher in placentas of patients with preeclampsia than placentas from the normal group. The significantly greater OSM expressions were noted in cytotrophoblasts, syncytotrophoblasts and endothelium of preeclamptic placentas as compared to normal placentas (respectively, P = 0.004, 0.001 and 0.04). OSM concentration of preeclamptic women's serum was significantly higher than that of normal women's plasma (P = 0.016). However, OSM level of umbilical venous serum was not significantly different between two groups (P = 0.243)
Conclusion: OSM may play a biological marker for severe preeclampsia, and its action may be predominantly on the trophoblasts and endothelium of placenta villi in preeclampsia.