Abstract-The risk of developing pregnancy-induced hypertension and preeclampsia is higher in obese pregnant women.In obesity, the composition of the gut microbiota is altered. Obesity is also associated with low-grade inflammation.Metabolites from the gut microbiota may contribute to both hypertension and inflammation. The aim of this study is to investigate whether the composition of the gut microbiota in overweight and obese pregnant women is associated with blood pressure and levels of plasminogen activator inhibitor-1. The composition of the gut microbiota was determined with 16S ribosomal RNA sequencing in 205 women at 16 weeks gestation from the SPRING study (the Study of Probiotics in Gestational Diabetes). Expression of butyrate-producing genes in the gut microbiota was assessed by realtime polymerase chain reaction. Plasminogen activator inhibitor-1 levels were measured in fasting serum of a subset of 70 women. Blood pressure was slightly but significantly higher in obese compared with overweight women. The abundance of the butyrate-producing genus Odoribacter was inversely correlated with systolic blood pressure. Butyrate production capacity was decreased, but plasminogen activator inhibitor-1 concentrations increased in obese pregnant women. Plasminogen activator inhibitor-1 levels were inversely correlated with expression of butyrate kinase and Odoribacter abundance. This study shows that in overweight and obese pregnant women at 16 weeks gestation, the abundance of butyrate-producing bacteria and butyrate production in the gut microbiota is significantly negatively associated with blood pressure and with plasminogen activator inhibitor-1 levels. Increasing butyrate-producing capacity may contribute to maintenance of normal blood pressure in obese pregnant women. Gomez-Arango et al Blood Pressure and Gut Microbiome Butyrate Production 975The SCFA butyrate is produced from dietary fiber by bacteria in the gastrointestinal lumen. There are 2 main enzymes catalyzing butyrate production: butyrate kinase (Buk) and butyryl-CoA:acetate CoA-transferase (But), which are often used as biomarkers for the detection of butyrate-producing bacteria.11 Buk catalyzes the formation of butyrate from butyryl-CoA, releasing ATP in the process. 12,13 But catalyzes the reaction of butyryl-CoA with exogenous acetate to form butyrate and acetyl-CoA.13,14 Some butyrate-producing bacteria only express But or Buk, whereas others express both. 12The main butyrate producers in the human gut belong to the Firmicutes phylum (Coprococci, Eubacterium, Roseburia, and Faecalibacterium genera), 14 but members of other phyla, especially Bacteroidetes (Odoribacter and Alistipes genera), often contribute to the overall butyrogenic pool. SCFAproducing bacteria may affect blood pressure by direct effects of SCFA on vasodilation or through plasminogen activator inhibitor-1 (PAI-1). n-Butyrate increases PAI-1 mRNA in cultured hepatocytes, 15 and SCFA enemas stimulate rectal microcirculation and PAI-1 after aortic graft surgery. 16 It is uncl...

Overweight and obese women are at a higher risk for gestational diabetes mellitus. The gut microbiome could modulate metabolic health and may affect insulin resistance and lipid metabolism. The aim of this study was to reveal relationships between gut microbiome composition and circulating metabolic hormones in overweight and obese pregnant women at 16 weeks' gestation. Fecal microbiota profiles from overweight (n = 29) and obese (n = 41) pregnant women were assessed by 16S rRNA sequencing. Fasting metabolic hormone (insulin, C-peptide, glucagon, incretin, and adipokine) concentrations were measured using multiplex ELISA. Metabolic hormone levels as well as microbiome profiles differed between overweight and obese women. Furthermore, changes in some metabolic hormone levels were correlated with alterations in the relative abundance of specific microbes. Adipokine levels were strongly correlated with Ruminococcaceae and Lachnospiraceae, which are dominant families in energy metabolism. Insulin was positively correlated with the genus Collinsella. Gastrointestinal polypeptide was positively correlated with the genus Coprococcus but negatively with family Ruminococcaceae. This study shows novel relationships between gut microbiome composition and the metabolic hormonal environment in overweight and obese pregnant women at 16 weeks' gestation. These results suggest that manipulation of the gut microbiome composition may influence pregnancy metabolism.The increasing prevalence of maternal obesity and its subsequent health outcomes are a significant public health concern and a major challenge for obstetrics practice. In early pregnancy, overweight and obese women are at an increased risk of metabolic complications that affect placental and embryonic development (1). Metabolic adjustments, such as a decline in insulin sensitivity and an increase in nutrient absorption, are necessary to support a healthy pregnancy (2,3); however, these metabolic changes occur on top of preexisting higher levels of insulin resistance in overweight and obese pregnant women, increasing the risk of overt hyperglycemia because of a lack of sufficient insulin secretion to compensate for the increased insulin resistance (3).The potential role of the gut microbiome (the composite of the bacteria present in the gastrointestinal tract) in pregnancy has become the subject of considerable interest. In normal pregnancy, the maternal gut microbiota changes from first to third trimester with a decline in butyrate-producing bacteria and an increase in Bifidobacteria, Proteobacteria, and lactic acid-producing bacteria. Inflammation and weight gain that occurs during pregnancy might be the result of microbe-driven processes to increase energy supply for the fetus (4). These alterations might also be linked with the maternal metabolic profile and thereby contribute to the development of pregnancy complications (5,6) as well as affect the metabolic and immunological health of the offspring (7). In summation, modifications in the metabolic hormone milieu du...

ANZCTR 12611001208998, registered 23/11/2011.