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Myeloid cells are the predominant cell type in the tumor microenvironment of human and murine glioblastoma (GBM). By generating a mouse model deficient for all monocyte chemoattractant proteins, here the authors show that blocking monocyte recruitment promotes a compensatory neutrophil influx and that concomitant neutrophil inhibition is required to improve survival in GBM preclinical models.

Abstract Background Juvenile Idiopathic Arthritis (JIA) is an autoimmune disease with a heterogenous clinical presentation and unpredictable response to available therapies. This personalized transcriptomics study sought proof-of-concept for single-cell RNA sequencing to characterize patient-specific immune profiles. Methods Whole blood samples from six untreated children, newly diagnosed with JIA, and two healthy controls were cultured for 24 h with or without ex vivo TNF stimulation and subjected to scRNAseq to examine cellular populations and transcript expression in PBMCs. A novel analytical pipeline, scPool, was developed wherein cells are first pooled into pseudocells prior to expression analysis, facilitating variance partitioning of the effects of TNF stimulus, JIA disease status, and individual donor. Results Seventeen robust immune cell-types were identified, the abundance of which was significantly affected by TNF stimulus, which resulted in notable elevation of memory CD8 + T-cells and NK56 cells, but down-regulation of naïve B-cell proportions. Memory CD8 + and CD4 + T-cells were also both reduced in the JIA cases relative to two controls. Significant differential expression responses to TNF stimulus were also characterized, with monocytes showing more transcriptional shifts than T-lymphocyte subsets, while the B-cell response was more limited. We also show that donor variability exceeds the small degree of possible intrinsic differentiation between JIA and control profiles. An incidental finding of interest was association of HLA-DQA2 and HLA-DRB5 expression with JIA status. Conclusions These results support the development of personalized immune-profiling combined with ex-vivo immune stimulation for evaluation of patient-specific modes of immune cell activity in autoimmune rheumatic disease.

Recent advances in developmental immunology have revealed a hematopoietic stem cell (HSC)-independent origin for various innate immune lineages, including mast cells (MCs). It is now established that adult bone marrow (BM) long-term HSCs do not regenerate MCs but, instead, the physiological production of MCs starts before the emergence of HSCs in the aorta-gonad-mesonephros (AGM) region and is mostly completed before birth. However, while the AGM region represents a major site of MC generation during ontogeny, whether the first emerging HSCs in the AGM or fetal liver (FL) possess the potential to regenerate MCs is unknown. Here, we combined three fate-mapping mouse models with detailed HSC transplantation assays to determine the potential of AGM and FL HSCs to produce MCs. We show that HSCs from E11.5 AGM and E12.5 FL efficiently repopulated MCs in recipients. In stark contrast, HSCs from ≥E14.5 FL failed to reconstitute MCs. An Endothelial (EC) fate-mapping study confirmed the EC origin of the majority of MCs. Additionally, our HSC-labeling showed that HSCs do not produce MCs in a physiological setting. Hence, although most MCs are generated and maintained via an HSC-independent pathway, the earliest HSCs to emerge in the AGM and seed the early FL can produce MCs, but only during a minimal time window. Our results challenge the stem cell theory in hematology and EC-derived mast cells may contribute to the pathogenesis of postnatal mast cell disorders.

Changes in the frequencies of cell subsets that (co)express characteristic biomarkers, or levels of the biomarkers on the subsets, are widely used as indices of drug response, disease prognosis, stem cell reconstitution, etc. However, although the currently available computational "gating" tools accurately reveal subset frequencies and marker expression levels, they fail to enable statistically reliable judgements as to whether these frequencies and expression levels differ significantly between/among subject groups. Here we introduce flow cytometry data analysis pipeline which includes the Earth Mover's Distance (EMD) metric as solution to this problem. Well known as an informative quantitative measure of differences between distributions, we present three exemplary studies showing that EMD 1) reveals clinically-relevant shifts in two markers on blood basophils responding to an offending allergen; 2) shows that ablative tumor radiation induces significant changes in the murine colon cancer tumor microenvironment; and, 3) ranks immunological differences in mouse peritoneal cavity cells harvested from three genetically distinct mouse strains.

BACKGROUND:Celastrol, an active compound extracted from the root of the Chinese medicine "Thunder of God Vine" (Tripterygium wilfordii), exhibits anticancer, antioxidant and anti-inflammatory activities, and interest in the therapeutic potential of celastrol is increasing. However, described side effects following treatment are significant and require investigation prior to initiating clinical trials. Here, we investigated the effects of celastrol on the adult murine hematopoietic system. METHODOLOGY/PRINCIPAL FINDINGS:Animals were treated daily with celastrol over a four-day period and peripheral blood, bone marrow, spleen, and peritoneal cavity were harvested for cell phenotyping. Treated mice showed specific impairment of the development of B cells and erythrocytes in all tested organs. In bone marrow, these alterations were accompanied by decreases in populations of common lymphoid progenitors (CLP), common myeloid progenitors (CMP) and megakaryocyte-erythrocyte progenitors (MEP). CONCLUSIONS/SIGNIFICANCE:These results indicate that celastrol acts through regulators of adult hematopoiesis and could be used as a modulator of the hematopoietic system. These observations provide valuable information for further assessment prior to clinical trials.