Characterization of Progesterone Receptor Membrane Component 1 in Peripheral Blood Mononuclear Cells and Plasma during Pregnancy

Objective: Progesterone receptor membrane component 1 (PGRMC1) is a novel membrane progesterone receptor that is highly expressed and actively regulated in gestational tissues. Research suggests that PGRMC1 plays a role in mediating progesterone function in gestational tissues and maintaining pregnancy. It has also been reported that PGRMC1 is detectable in the plasma and peripheral blood mononuclear cells (PBMCs) in patients with cancer and may serve as a biomarker. Therefore, our objective is to identify whether PGRMC1 is present in plasma and PBMCs during pregnancy and thus may be investigated as a candidate biomarker for obstetric pathology including preterm birth. Study design: Whole blood samples were collected from pregnant patients. Plasma and PBMCs were isolated. Western blot and immunoprecipitationmass spectrometry (IP-MS) were used to investigate the presence of PGRMC1 in plasma. Flow cytometry and Western blot were used to detect PGRMC1 expression in PBMCs collected from pregnant subjects. Results: Flow cytometry and Western blot results confirmed that PGRMC1 is differentially expressed in different cell types of PBMCs. However, Western blot and IP-MS results demonstrated that PGRMC1 is undetectable in plasma samples from pregnant women. Conclusions: This pilot study characterized the presence of PGRMC1 in the bloodstream during pregnancy. PGRMC1 is differentially expressed in different cell types of PBMCs of pregnant subjects but is not detectable in the plasma of these subjects. These data provide a foundation for future evaluation of PGRMC1 in PBMCs as a potential novel biomarker for PTB.