TLR4 activation enhances the PD-L1-mediated tolerogenic capacity of colonic CD90+stromal cells

Ellen J. Beswick, Jameel Johnson, Jamal I. Saada, Martin Humen, Jenifer House, Sara Dann, Suimin Qiu, Allan Brasier, Don Powell, Victor E. Reyes, Iryna Pinchuk

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Signaling via programmed death ligand-1 (PD-L1) and PD-L2 is crucial for maintaining peripheral tolerance. CD90+myofibroblasts/fibroblasts (CMFs) are major programmed cell death-1 (PD-1) ligand-expressing cells in normal human colonic mucosa. CMFs suppress activated CD4+T cell proliferation via PD-1 ligands. It is not known whether signaling through TLRs contribute to the regulation PD-1 ligands on CMFs upon colonic mucosal tolerance. In this study, we demonstrated that stimulation of TLR4 on human CMFs upregulates PD-L1, but not PD-L2, and reinforces CMF-mediated suppression of CD4+T cell proliferation and IFN-γ production. TLR4-mediated upregulation of PD-L1 on CMFs involved NF-κB pathways and was JAK2 and MyD88 dependent. MyD88-dependent stimulation of TLR1/2 and TLR5 also upregulated PD-L1 expression on CMFs in culture. PD-L1 expression was drastically decreased in vivo in the colonic mucosa of mice devoid of MyD88. Induction of MyD88 deficiency in CMFs in fibroblast-specific MyD88 conditional knockout mice resulted in a strong increase in a mucosal IFN-γ expression concomitantly with the abrogation of PD-L1 expression in CMFs under homeostasis and epithelial injury induced by dextran sodium sulfate. Together, these data suggest that MyD88-dependent TLR stimulation of CMFs in the normal colonic mucosa may reinforce these cells' anti-inflammatory capacity and thus contribute to the maintenance of mucosal tolerance.

Original languageEnglish (US)
Pages (from-to)2218-2229
Number of pages12
JournalJournal of Immunology
Volume193
Issue number5
DOIs
StatePublished - Sep 1 2014

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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