Mesenteric lymph node stromal cell-derived extracellular vesicles contribute to peripheral de novo induction of Foxp3+ regulatory T cells

Eur J Immunol. 2017 Dec;47(12):2142-2152. doi: 10.1002/eji.201746960. Epub 2017 Sep 15.

Abstract

Intestinal regulatory T cells (Tregs) are fundamental in peripheral tolerance toward commensals and food-borne antigens. Accordingly, gut-draining mesenteric lymph nodes (mLNs) represent a site of efficient peripheral de novo Treg induction when compared to skin-draining peripheral LNs (pLNs), and we had recently shown that LN stromal cells substantially contribute to this process. Here, we aimed to unravel the underlying molecular mechanisms and generated immortalized fibroblastic reticular cell lines (iFRCs) from mLNs and pLNs, allowing unlimited investigation of this rare stromal cell subset. In line with our previous findings, mLN-iFRCs showed a higher Treg-inducing capacity when compared to pLN-iFRCs. RNA-seq analysis focusing on secreted molecules revealed a more tolerogenic phenotype of mLN- as compared to pLN-iFRCs. Remarkably, mLN-iFRCs produced substantial numbers of microvesicles (MVs) that carried elevated levels of TGF-β when compared to pLN-iFRC-derived MVs, and these novel players of intercellular communication were shown to be responsible for the tolerogenic properties of mLN-iFRCs. Thus, stromal cells originating from mLNs contribute to peripheral tolerance by fostering de novo Treg induction using TGF-β-carrying MVs. This finding provides novel insights into the subcellular/molecular mechanisms of de novo Treg induction and might serve as promising tool for future therapeutic applications to treat inflammatory disorders.

Keywords: Extracellular vesicles; Fibroblastic reticular cells; Intestinal tolerance; Mesenteric lymph nodes; Regulatory T cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Extracellular Vesicles / genetics
  • Extracellular Vesicles / immunology*
  • Extracellular Vesicles / ultrastructure
  • Forkhead Transcription Factors / immunology
  • Forkhead Transcription Factors / metabolism
  • Gene Expression Profiling / methods
  • Lymph Nodes / immunology*
  • Mesentery / immunology
  • Mice, Inbred BALB C
  • Mice, Knockout
  • Microscopy, Electron, Scanning
  • Microscopy, Electron, Transmission
  • Stromal Cells / immunology*
  • Stromal Cells / metabolism
  • Stromal Cells / ultrastructure
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / immunology

Substances

  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • Transforming Growth Factor beta