The generation of abundant inducible pluripotent stem cell derived immunoregulatory dendritic cells to promote antigen-specific immune regulation 2255471
TL;DR
Efficient generation of iDC3s is demonstrated, their developmental trajectory, and regulatory potential are defined, and how DC3s operate across disease contexts are revealed, revealing how DC3s operate across disease contexts.
Abstract
Dendritic cells are a rare lineage, consisting of cDC1, cDC2, and the scarce (< 0.3% of blood) DC3. Uniquely, DC3s share monocyte and cDC2 features, marked by co-expression of CD1c and CD14. They promote Th1 and Th17 cells, associate with autoimmunity, and induce CD8+CD103+ tissue-resident memory T-cells that may exacerbate disease. Contrarily, DC3s can be immunosuppressive in a tumor microenvironment. This duality could provide an immunotherapy platform if sufficient-numbers can be obtained. HSPCs were generated from iPSCs via embryoid bodies; HSPCs were cultured for 2 weeks on murine MS5 stromal cells with SCF, FLT3L, and ascorbic acid. To induce regulatory iDC3s (iDC3regs), CD1c+ isolated cells were treated for 24hrs with CHIR99021 (Wnt agonist), L-kyneurine, retinoic acid and IFNγ, IL-10, and/or TGFβ (γ10β), the latter tested alone and in combination. Suppressive function was measured via AlloMLRs. iDC3s emerged with a fold-increase of 1096±123 iDC3s per iPSC in 4 maturation states: CD45RA+CD14- (immature), CD45RA-CD14-, CD45RA-CD14+ CD163-, and CD14+CD163 + (mature). Isolated CD1c+ iDC3s cultured with GM-CSF, known to support DC3s, not FLT3L, gradually promoted maturation to a CD14+CD163+ over 3 days. γ10β-iDC3regs were most suppressive, mediated through PDL1 and IDO1. Interestingly, γ10β rapidly induced two states: CD14+CD163- and CD14+CD163+ that resisted inflammatory exposure (TNF+/IL1β/PGE2, LPS, CpG, R848, or GMCSF/IL4). Bulk RNA-seq of these populations is underway to define the regulatory profile and to compare public DC3 datasets. Studies in humanized mouse graft-versus-host disease models will test iDC3regs in vivo regulatory capacity; Studies examining tumor antigen-loaded and activated iDC3s will test their anti-tumor potential. We demonstrate efficient generation of iDC3s, define their developmental trajectory, and regulatory potential. These findings reveal how DC3s operate across disease contexts. Kidz1stFund, P01CA065493-28 Transplantation Immunology (TRAN)