title: Lipopolysaccharide and double stranded viral RNA mediate insulin resistance and increase system a amino acid transport in human trophoblast cells in vitro.
abstract: Inflammation and underlying low-grade maternal infection can impair insulin signalling and upregulate nutrient transport in the placenta which contribute to fetal overgrowth associated with GDM and/or obese pregnancies. There are, however, no studies on the role of infection on placental nutrient transport in pregnancies complicated by GDM and/or obesity. Thus, the aims of this study were to determine the effect of the bacterial product lipopolysaccharide (LPS) or the viral dsRNA analogue polyinosinic:polycytidylic acid (poly(I:C)) on the insulin signalling pathway and amino acid transport in primary human trophoblast cells.
  
  
  
  Human primary villous trophoblast cells were treated with LPS or poly(I:C). Protein expression of insulin signalling pathway proteins, insulin receptor (IR)-β, insulin receptor substrate (IRS)-1 and protein kinase B (also known as Akt), and phosphatidylinositol-4,5-bisphosphate 3-kinase p85α subunit (PI3K-p85α) protein were assessed by Western blotting. Glucose and amino acid uptake were assessed by radiolabelled assay. Western blotting and qRT-PCR were used to determine amino acid transporter protein and mRNA expression, respectively.
  
  
  
  LPS and poly(I:C) significantly decreased phosphorylation of IR-β, IRS-1, Akt, total PI3K-p85α protein expression and glucose uptake. LPS and poly(I:C) also significantly increased expression of System A amino acid transporters SNAT1 and SNAT2, and System A-mediated uptake of amino acids.
  
  
  
  LPS and poly(I:C) induces insulin resistance and increases amino acid uptake in human primary trophoblast cells. This suggests that the presence of low-grade maternal infection can contribute to excess placental nutrient availability and promote fetal overgrowth in pregnancies complicated by GDM and/or obesity.
authors.affiliation: Mercy Perinatal Research Centre, Mercy Hospital for Women, Heidelberg, Victoria, Australia; Obstetrics, Nutrition and Endocrinology Group, Department of Obstetrics and Gynaecology, University of Melbourne, Victoria, Australia.
authors.forename: Stella
authors.initials: S
authors.lastname: Liong
authors.affiliation: Mercy Perinatal Research Centre, Mercy Hospital for Women, Heidelberg, Victoria, Australia; Obstetrics, Nutrition and Endocrinology Group, Department of Obstetrics and Gynaecology, University of Melbourne, Victoria, Australia. Electronic address: mlappas@unimelb.edu.au.
authors.forename: Martha
authors.initials: M
authors.lastname: Lappas
mesh_terms: D026924:Amino Acid Transport System A / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011070:Poly I-C / Q000494:pharmacology; D011247:Pregnancy; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012367:RNA, Viral; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014327:Trophoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D026924:Amino Acid Transport System A; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D008070:Lipopolysaccharides; D012367:RNA, Viral; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D011070:Poly I-C
keywords: Amino acid transport; Bacterial infection; Insulin resistance; Obesity; Placenta; Viral infection