Differential gene expression in obese pregnancy

Maternal obesity is a major risk factor for maternal and perinatal complications, and is associated with increased risk of premature cardiovascular death in the offspring. We aimed to identify differentially expressed genes in obese and lean pregnancies. Pregnant women were recruited antenatally and whole-blood samples taken at gestational week 28. Women were classified as lean (BMI<25, n=5), overweight (BMI 25-30, n=11) or obese (BMI>30, n=4). Subcutaneous adipose tissue was obtained from a separate cohort of women undergoing elective Caesarean section (n=3 lean, n=6 overweight, n=9 obese). Total RNA was isolated and gene expression profiled by Illumina microarray technology. Differential gene expression was identified by Ingenuity Pathway Analysis and validated by TaqMan qRT-PCR. In whole blood, differential expression (p<0.05) of six genes (ANGPTL, COX7A2, EIF3A, PTS, CISD1 and GLRX) was identified between lean and non-lean pregnant women by microarray. When gene expression was studied in subcutaneous tissues, we observed a trend towards lower expression of the cytochrome c oxidase-subunit 7A2 gene (COX7A2) in overweight vs lean (p=0.057) and obese vs lean (p=0.06) women, whereas expression was similar between overweight and obese women (p=0.55). Other genes were not differentially expressed across groups. Maternal obesity is associated with differential expression of multiple genes in whole blood. In subcutaneous tissue at term, there was a trend towards reduced COX7A2 expression in obese women. COX7A2 is a mitochondrial protein, with key roles in steroidogenesis and oxidative stress regulation and could provide a link between inflammation and obesity-related pregnancy complications.