Slit2 exerts anti-inflammatory actions in human placenta and is decreased with maternal obesity

Am J Reprod Immunol. 2015 Jan;73(1):66-78. doi: 10.1111/aji.12334. Epub 2014 Oct 20.

Abstract

Problem: Obese pregnancies are characterised by increased inflammation. Members of the Slit/Roundabout (Robo) family are key regulators of the inflammatory response. The aim of this study was to determine the effect of (i) pre-existing maternal obesity on Slit-Robo expression in human placenta and (ii) Slit2 knockdown by siRNA in primary trophoblast cells on markers of inflammation.

Method of study: The expression of Slit-Robo protiens was assessed in human placenta from lean (n = 15) and obese (n = 16) patients by qRT-PCR and Western blotting. Primary trophoblast cells were used to determine the effect of pro-inflammatory mediators on Slit2 expression, and the effect of Slit2 siRNA on pro-inflammatory mediators.

Results: While there was no change in Slit3, Robo1 or Robo4 expression, Slit2 expression was significantly lower in obese placenta compared to lean placenta. Human primary trophoblast cells treated with pro-inflammatory mediators IL-1β, TNF-α and LPS significantly decreased Slit2 expression. Slit2 silencing by siRNA augmented IL-6 expression and secretion in cells stimulated with TNF-α, LPS and TNF-α; IL-8 gene expression and/or release in cells stimulated with IL-1β and LPS; TNF-α gene expression and secretion in cells stimulated with LPS; and MMP-9 gene expression and pro MMP-9 levels in cells stimulated with TNF-α.

Conclusion: The anti-inflammatory effects of Slit2 in human placenta is a novel finding, and suggests that inflammatory mediators, which are increased with obesity, downregulates Slit2 to enhance placental inflammation. Given the central role of pro-inflammatory cytokines in placental nutrient transport, our findings suggest Slit2 may play a role in fetal growth and development.

Keywords: Slit2; cytokines; inflammation; obesity; placenta.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cells, Cultured
  • Cytokines / genetics
  • Cytokines / metabolism
  • Down-Regulation / genetics
  • Female
  • Gene Expression Regulation, Developmental / genetics
  • Humans
  • Inflammation / genetics
  • Inflammation / immunology*
  • Inflammation Mediators / immunology
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Lipopolysaccharides / immunology
  • Matrix Metalloproteinase 9 / genetics
  • Matrix Metalloproteinase 9 / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Obesity / genetics
  • Obesity / immunology*
  • Placenta / physiology*
  • Placenta / physiopathology
  • Pregnancy
  • Pregnancy Complications / genetics
  • Pregnancy Complications / immunology*
  • RNA, Small Interfering / genetics
  • Trophoblasts / cytology
  • Trophoblasts / physiology*

Substances

  • Cytokines
  • Inflammation Mediators
  • Intercellular Signaling Peptides and Proteins
  • Lipopolysaccharides
  • Nerve Tissue Proteins
  • RNA, Small Interfering
  • Matrix Metalloproteinase 9
  • Slit homolog 2 protein