title: Hepatic stellate cells increase the immunosuppressive function of natural Foxp3+ regulatory T cells via IDO-induced AhR activation.
abstract: Immunosuppressive, naturally occurring CD4+CD25+forkhead box p3+(Foxp3+) regulatory T cells (nTregs) offer potential for the treatment of immune-mediated inflammatory disorders. However, potential instability of ex vivo-expanded nTregsfollowing their adoptive transfer may be a significant limitation. LPS-stimulated hepatic stellate cells (HSCs) induce expansion and enhance the suppressive function and stability of allogeneic nTregsWe aimed to delineate mechanisms underlying HSC-induced expansion and increased potency of nTregsHSCs and nTregswere isolated from mouse livers and spleens, respectively. Following coculture with LPS-pretreated allogeneic HSCs (LPS/HSCs), proliferation of nTregswas measured by CFSE dilution, and Foxp3 expression and acetylation were determined by immunoprecipitation (IP) and Western blotting analysis. Expression of various genes associated with immunologic tolerance was determined by quantitative RT-PCR (qRT-PCR). LPS stimulation increased the expression and activity of the immunoregulatory enzyme IDO1 in HSCs, and LPS/HSCs stimulated aryl hydrocarbon receptor (AhR) signaling in cocultured nTregsReciprocally, Tregsincreased IDO1 expression in HSCs. IDO1-/-LPS/HSCs were inferior to WT LPS/HSCs in stimulating nTregexpansion. Pharmacologic inhibition of IDO1 in HSCs by 1-methyltryptophan (1MT) inhibited LPS/HSC-induced AhR signaling in nTregs, which was responsible for their expansion, Foxp3 expression, and stabilization of Foxp3 by increasing acetylation of lysine residues. Finally, HSCs cryopreserved, following 2-3 passages, were as potent as primary-cultured HSCs in expanding nTregsIn conclusion, LPS/HSCs expand allogeneic nTregsthrough an IDO-dependent, AhR-mediated mechanism and increase their stability through lysine-acetylation of Foxp3. nTregsexpanded by cryopreserved HSCs may have potential for clinical use.
authors: Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA.|Cincinnati VA Medical Center, Cincinnati, Ohio, USA.
authors: Sudhir
authors: S
authors: Kumar
authors: Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA.
authors: Jiang
authors: J
authors: Wang
authors: Thomas E. Starzl Transplantation Institute, Departments of Surgery and Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA; and.
authors: Angus W
authors: AW
authors: Thomson
authors: Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA; chandrashekhar.gandhi@cchmc.org.|Cincinnati VA Medical Center, Cincinnati, Ohio, USA.|Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors: Chandrashekhar R
authors: CR
authors: Gandhi
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D015925:Cryopreservation; D016207:Cytokines / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D055166:Hepatic Stellate Cells / Q000187:drug effects / Q000378:metabolism*; D007165:Immunosuppression Therapy; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism*; D008070:Lipopolysaccharides; D008807:Mice, Inbred BALB C; D010766:Phosphorylation / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; C583637:IDO1 protein, mouse; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D008070:Lipopolysaccharides; D018336:Receptors, Aryl Hydrocarbon; D016160:Retinoblastoma Protein; D014364:Tryptophan; C525396:1-methyltryptophan
keywords: acetylation; cytokines; endotoxin; l-kynurenine; tolerance