| First Author | Beswick EJ | Year | 2014 |
| Journal | J Immunol | Volume | 193 |
| Issue | 5 | Pages | 2218-29 |
| PubMed ID | 25070848 | Mgi Jnum | J:317662 |
| Mgi Id | MGI:6843828 | Doi | 10.4049/jimmunol.1203441 |
| Citation | Beswick EJ, et al. (2014) TLR4 activation enhances the PD-L1-mediated tolerogenic capacity of colonic CD90+ stromal cells. J Immunol 193(5):2218-29 |
| abstractText | 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-gamma production. TLR4-mediated upregulation of PD-L1 on CMFs involved NF-kappaB 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-gamma 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. |
