Significance of placental CD200 expression in patients with preeclampsia: Comparison between early- and late-onset patients

Preeclampsia, characterized by high blood pressure and proteinuria during pregnancy, causes serious complications in both the mother and the fetus. Although there have been several studies on the causes of preeclampsia, the detailed mechanism of this disease remains unclear. Moreover, a few reports have focused on the causes of preeclampsia in number of weeks at onset. The present study aimed to elucidate the differences between early- and late-onset preeclampsia. This study enrolled patients with preeclampsia from January 2014 to December 2020. They were classified into early- (<34 weeks) and late-onset (>= 34 weeks) preeclampsia groups. The expression profiles of 770 immune-related genes were studied in the placental tissue from five patients each in the early- and late-onset groups. The expression of CD200 in the trophoblasts of the placenta of 26 and 27 patients in early- and late-onset groups, respectively, was also analyzed using immunostaining. Analysis of extracted RNA indicated that CD200 was significantly upregulated in the early-onset group compared with late-onset group and normal control. Immunostaining for CD200 demonstrated a significantly increased expression in the early-onset group compared with the late-onset group. The present study demonstrated that upregulation of CD200, which belongs to the immunoglobulin superfamily and is recognized as a molecule that acts in immune tolerance via inhibition of classical macrophage activation, may be associated with early-onset preeclampsia, although it remains unknown whether upregulation of CD200 expression is a cause or effect of the development of early-onset preeclampsia. Early-onset preeclampsia might have a different mechanism from that of late-onset; thus, further studies are needed to clarify the mechanism of these conditions for adequate treatment.