Maternal obesity is not associated with placental lipid accumulation in women with high omega-3 fatty acid levels

Abstract

Introduction: Placentas of obese women have higher lipid content compared to lean women. We have previously shown that supplementation of overweight and obese women with omega-3 fatty acids decreases placental esterification pathways and total lipid content in a mid-western population (Ohio). We hypothesized that placental lipid accumulation and inflammation would be similar between lean and obese women living in a region of high omega-3 intake, such as Hawaii.

Methods: Fifty-five healthy, normal glucose tolerant women from Honolulu Hawaii, dichotomized based on pre-pregnancy BMI into lean (BMI <25 kg/m², n = 29) and obese (BMI >30 kg/m², n = 26), were recruited at scheduled term cesarean delivery. Maternal plasma DHA levels were analyzed by mass spectrometry. Expression of key genes involved in fatty acid oxidation and esterification were measured in placental tissue using qPCR. Total lipids were extracted from placental tissue via the Folch method. TNF-α concentration was measured by enzyme-linked immunosorbent assay in placental lysates.

Results: DHA levels were higher in lean women compared to obese women (P = 0.02). However, DHA levels in obese women in Hawaii were eight times higher compared to obese Ohioan women (P=<0.0001). Placental lipid content and expression of key genes involved in fatty acid oxidation and esterification were similar (P > 0.05) between lean and obese women in Hawaii. Furthermore, TNF-α placental lysates were not different between lean and obese women.

Conclusions: Though obese women in Hawaii have lower DHA levels compared to their lean counterparts, these levels remain over eight times as high as obese Ohioan women. These relatively high plasma omega-3 levels in obese women in Hawaii may suppress placental lipid esterification/storage and inflammation to the same levels of lean women, as seen previously in vitro.

Keywords: Esterification; Inflammation; Obesity; Omega-3 fatty acids; Placenta.

Figure 1.. Maternal plasma DHA levels in lean and obese women

DHA concentrations were analyzed by gas chromatography/mass spectrometry and expressed as μmol/L. Data are mean ± standard error of the mean. *P<0.05 obese vs lean by Student’s t-test. ^This line represents the mean maternal DHA of 10 obese women from Ohio (41 ± 28 μmol/L).

Figure 2.. Placenta lipid content in lean and obese women.

Total lipid extracted using the Folch method and normalized to tissue weight. Data are mean ± standard error of the mean.

Figure 3.. Effect of high omega-3 on placental FA esterification pathway gene expression.

mRNA expression of placental genes involved in FA esterification from 29 lean and 26 obese placentas. Data (mean ± standard error of the mean) are expressed as the ratio of gene of interest: reference gene (L19).

Figure 4.. Effect of high omega-3 on placental FA oxidation gene expression

mRNA expression of placental genes involved in FA oxidation from 29 lean and 26 obese placentas. Data (mean ± standard error of the mean) are expressed as the ratio of gene of interest: reference gene (L19). Mitochondrial number was indicated by the ratio of CytB/β-actin DNA. *P≤ 0.05 obese vs lean by Student’s t-test.