Commensal Streptococcus salivarius Modulates PPARγ Transcriptional Activity in Human Intestinal Epithelial Cells

PLoS One. 2015 May 6;10(5):e0125371. doi: 10.1371/journal.pone.0125371. eCollection 2015.

Abstract

The impact of commensal bacteria in eukaryotic transcriptional regulation has increasingly been demonstrated over the last decades. A multitude of studies have shown direct effects of commensal bacteria from local transcriptional activity to systemic impact. The commensal bacterium Streptococcus salivarius is one of the early bacteria colonizing the oral and gut mucosal surfaces. It has been shown to down-regulate nuclear transcription factor (NF-кB) in human intestinal cells, a central regulator of the host mucosal immune system response to the microbiota. In order to evaluate its impact on a further important transcription factor shown to link metabolism and inflammation in the intestine, namely PPARγ (peroxisome proliferator-activated receptor), we used human intestinal epithelial cell-lines engineered to monitor PPARγ transcriptional activity in response to a wide range of S. salivarius strains. We demonstrated that different strains from this bacterial group share the property to inhibit PPARγ activation independently of the ligand used. First attempts to identify the nature of the active compounds showed that it is a low-molecular-weight, DNase-, proteases- and heat-resistant metabolite secreted by S. salivarius strains. Among PPARγ-targeted metabolic genes, I-FABP and Angptl4 expression levels were dramatically reduced in intestinal epithelial cells exposed to S. salivarius supernatant. Both gene products modulate lipid accumulation in cells and down-regulating their expression might consequently affect host health. Our study shows that species belonging to the salivarius group of streptococci impact both host inflammatory and metabolic regulation suggesting a possible role in the host homeostasis and health.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiopoietin-Like Protein 4
  • Angiopoietins / biosynthesis
  • Angiopoietins / genetics
  • Caco-2 Cells
  • Cell Line, Tumor
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism
  • Fatty Acid-Binding Proteins / biosynthesis
  • Fatty Acid-Binding Proteins / genetics
  • Gene Expression Regulation
  • HT29 Cells
  • Humans
  • Immunity, Mucosal / immunology
  • Intestinal Mucosa / cytology
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / microbiology
  • Microbiota / immunology
  • PPAR gamma / biosynthesis*
  • PPAR gamma / genetics
  • Streptococcus / immunology
  • Streptococcus / metabolism*
  • Symbiosis
  • Transcription, Genetic / genetics*
  • Transcriptional Activation / genetics*

Substances

  • ANGPTL4 protein, human
  • Angiopoietin-Like Protein 4
  • Angiopoietins
  • Fatty Acid-Binding Proteins
  • PPAR gamma

Grants and funding

This work was supported by Institut National de la Recherche Agronomique and financed by grants from the European Community’s Seventh Framework Program (FP7/2007-2013), MetaHIT, grant agreement HEALTH-F4-2007-201052, the ANR project MetaGenoPolis (ANR-11-DPBS-0001) and the ANR Blanc FunMetaGen. BC was a recipient of a grant from the ministère de la Recherche et de l’Education Nationale (ED425).