Human Placental Lipid Content and Lipid Metabolic Enzyme Abundance in Obesity and Across Gestation.

Changes in placental lipid metabolism influence the delivery of lipids critical for fetal development and fetal requirements for lipids change across gestation. We hypothesized that placental lipid content and metabolic enzyme protein levels increase across gestation and are elevated in obesity. Placentas (4-40 weeks gestation) were collected from control (body mass index, BMI 18.5-24.9, n=37) and obese (BMI>30, n=19) pregnant women. Trophoblast villous tissue was homogenized and subjected to LC-MS/MS for phospholipid and triacylglycerol (TAG) analysis and western blot for protein quantification. The placental content of TAG species and 9 of 35 identified phosphatidylcholines (PC) were significantly higher (P<0.05) in first trimester (28-79%, 10-47%, respectively). Further, two TAG and three PC differed by maternal BMI and were significantly increased (P<0.05) in the obese group in first trimester (72-87%, 88-119%, respectively). Placental protein abundance of GPAT3 and AGPAT2, involved in de novo synthesis of PC and TAG, were higher (P<0.05) in the first trimester (66% and 74%, respectively). The protein abundance of the PC remodeling enzyme PLA2G4c was also higher (63%) in first trimester (P<0.05). In conclusion, the placental content of many phospholipid and TAG species and the protein level of associated synthesis enzymes are higher in first trimester human placenta.  The high PC content may be related to the rapid membrane expansion in early pregnancy and the low placental oxygen tension may promote the accumulation of tissue TAGs in first trimester.  Maternal obesity had only limited impact on placental lipid content and metabolic enzyme protein abundance.