Generation of Large Numbers of Myeloid Progenitors and Dendritic Cell Precursors from Murine Bone Marrow Using a Novel Cell Sorting Strategy

Aryl hydrocarbon receptor activation ameliorates experimental colitis by modulating the tolerogenic dendritic and regulatory T cell formation

Background

Intestinal immune dysfunction is involved in the onset of Crohn’s disease (CD). Dendritic cells (DCs), antigen-presenting cells, play a key role in the maintenance of intestinal immune homeostasis. The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor widely expressed in various immune cells, including DCs. Although AhR plays an important role in immune tolerance, its role in the DCs is unclear. The purpose of this study was to investigate whether the activation of AhR can induce tolerogenic DCs (tolDCs) and the differentiation of regulatory T (Treg) cells, as well as ameliorate experimental colitis.

Results

AhR activation in the DCs resulted in a lower expression of surface markers such as CD80, CD83, CD86, and pro-inflammatory cytokine production, and higher anti-inflammatory production (IL-1β, IL-23, and IL-12) compared to the control DCs. The surface dendrites in DCs were significantly reduced following AhR activation by 6-formylindolo [3,2-b]carbazole (FICZ). Such DCs with FICZ-mediated activation of AhR, namely tolDCs, promoted Treg cell differentiation. Adoptive transfer of tolDCs to a TNBS-induced colitis mouse model significantly alleviated the severity of inflammation by improving the colon length and decreasing the disease activity index (DAI) and histopathological score. Moreover, the transferred tolDCs decreased the frequency of Th17 cells and increased the frequency of Treg cells in the spleen and mesenteric lymph nodes (MLNs) in murine colitis models.

Conclusions

Activation of AhR in the DCs could induce tolDCs, and the transplantation of tolDCs may help in relieving intestinal inflammation and maintaining the Th17/Treg differentiation balance. Thus, our data suggest that AhR may be a potential therapeutic target for CD.

High-Yield Human Induced Pluripotent Stem Cell-Derived Monocytes and Macrophages Are Functionally Comparable With Primary Cells

Macrophages are pivotal effectors of host immunity and regulators of tissue homeostasis. Understanding of human macrophage biology has been hampered by the lack of reliable and scalable models for cellular and genetic studies. Human induced pluripotent stem cell (hiPSC)-derived monocytes and macrophages, as an unlimited source of subject genotype-specific cells, will undoubtedly play an important role in advancing our understanding of macrophage biology and implication in human diseases. In this study, we present a fully optimized differentiation protocol of hiPSC-derived monocytes and granulocyte-macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF). We present characterization of iPSC-derived myeloid lineage cells at phenotypic, functional, and transcriptomic levels, in comparison with corresponding subsets of peripheral blood-derived cells. We also highlight the application of hiPSC-derived monocytes and macrophages as a gene-editing platform for functional validation in research and drug screening, and the study also provides a reference for cell therapies.