One of the most common genetic alterations in acute myeloid leukemia is the internal tandem duplication (ITD) in the FLT3 receptor for cytokine FLT3 ligand (FLT3L). The constitutively active FLT3-ITD promotes the expansion of transformed progenitors, but also has pleiotropic effects on normal hematopoiesis. We analyzed the effect of FLT3-ITD on dendritic cells (DCs), which express FLT3 and can be expanded by FLT3L administration. We report that young pre-leukemic mice with the Flt3ITD knock-in allele manifest an expansion of all DCs including classical (cDCs) and plasmacytoid (pDCs). The expansion originated in DC progenitors, occurred in a cell-intrinsic manner and was further enhanced in Flt3ITD/ITD mice. The mutation caused the downregulation of Flt3 on the surface of DCs and reduced their responsiveness to Flt3L. Flt3ITD mice showed enhanced capacity to support T cell proliferation, including a cell-extrinsic expansion of regulatory T cells (Tregs). Accordingly, these mice restricted alloreactive T cell responses during graft-versus-host reaction, but failed to control autoimmunity in the absence of Tregs. Thus, the FLT3-ITD mutation directly affects DC development, thereby indirectly modulating T cell homeostasis and supporting Treg expansion. This effect of FLT3-ITD may subvert immunosurveillance and promote leukemogenesis in a cell-extrinsic manner. Overall design: Sorted splenic dendritic cell subsets from either Flt3+/+ or Flt3ITD/+ mice were sequenced for mRNA profiling. For each subset per genotype contains 2-3 replicates, all from independent experiments.
Leukemia-associated activating mutation of Flt3 expands dendritic cells and alters T cell responses.
Specimen part, Cell line, Subject
View SamplesGoal: To compare the gene expression profiles from pediatric patients with each other, with those reported in adults and in those related to exosomes.
Differential gene expression of soluble CD8+ T-cell mediated suppression of HIV replication in three older children.
Sex, Specimen part
View SamplesBackground: Tissue macrophages contribute to development and protection, both requiring appropriately timed and located source(s) of factors controlling growth, cell differentiation and migration. Goal: To understand the role of microglia (tissue macrophages of the central nervous system), in promoting neurodevelopment and controlling neuroinflammation. Summary of findings: We show that microglia fulfill both these roles. In contrast to adult cells, neonatal microglia show a unique neurogenic phenotype with stem cell-like potential. Neonatal microglia are protective against neuroinflammation, and their transplantation ameliorates experimental autoimmune encephalomyelitis. A CD11c+ microglial subset predominates in primary myelinating areas of the developing brain and expresses genes for neuronal and glial survival, migration and differentiation. CD11c+ microglia are also found in clusters of repopulating microglia after experimental ablation and in neuroinflammation in adult mice, but despite some similarities, they do not recapitulate neurogenic neonatal microglia characteristics. Conclusions: We therefore identify a unique phenotype of neonatal microglia that deliver signals necessary for neurogenesis and myelination and suppress neuroinflammation. Overall design: The overall design was to compare transcriptomes of subsets of microglia isolated from neonatal mice, healthy adults, and adult mice with a neuroinflammatory disease (Experimental autoimmune encephalomyelitis, EAE), and to compare anti-inflammatory function of adult and neonatal microglia. Microglia were isolated by cell-sorting based on surface phenotype, and RNAseq data was analyzed using WGCNA, GO and DAVID approaches. Expression of selected genes and pathways was confirmed by histology and flow cytometry. Functional analysis involved transfer of isolated microglia to the central nervous system of animals with EAE and evaluation of outcome. EAE = Experimental autoimmune encephalomyelitis
A novel microglial subset plays a key role in myelinogenesis in developing brain.
Subject
View SamplesWe explored the hypothesis that Serotonin (5HT) receptor signaling, that can be enhanced with 5HT transporter blockade with Fluoxetine (Fluox), in the aortic valve may vary based upon the biomechanical activity of the aortic valve leaflet.
Aortic valve cyclic stretch causes increased remodeling activity and enhanced serotonin receptor responsiveness.
Specimen part, Disease, Treatment
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