Biology subjects

Ekoff, M.

Publications and source records attributed to Ekoff, M..

3 recordsLinked to original sources

bioRxiv2021

Single-cell transcriptomics reveals the identity and regulators of human mast cell progenitors

Mast cell accumulation is a hallmark of a number of diseases including allergic asthma and systemic mastocytosis. IgE-mediated crosslinking of the Fc{varepsilon}RI receptors causes mast cell activation and contributes to disease pathogenesis. The mast cell lineage is one of the least studied among the hematopoietic cell lineages and there are still controversies about the identity of the mast cell progenitor, i.e., whether Fc{varepsilon}RI expression appears during the hematopoietic progenitor stage or in maturing mast cells. Here, we used single-cell transcriptomics to reveal a temporal association between the appearance of Fc{varepsilon}RI and the mast cell gene signature in CD34+ hematopoietic progenitors. In agreement with these data, the Fc{varepsilon}RI+ hematopoietic progenitors formed morphologically, phenotypically and functionally mature mast cells in long-term culture assays. Single-cell transcriptomics analysis further revealed the expression patterns of prospective cytokine receptors regulating mast cell progenitor development. Culture assays showed that IL-3 and IL-5 promoted disparate effects on progenitor cell proliferation and survival, respectively, whereas IL-33 caused robust Fc{varepsilon}RI downregulation. Taken together, we have demonstrated that Fc{varepsilon}RI appears during the hematopoietic progenitor stage of mast cell differentiation and that external stimuli may regulate the Fc{varepsilon}RI expression. Thus, the results resolve the controversy regarding the appearance of Fc{varepsilon}RI during mast cell development. One-sentence summarySingle-cell analysis of human hematopoiesis uncovers the stage at which Fc{varepsilon}RI appears during mast cell differentiation and reveals disparate effects of IL-3, IL-5 and IL-33 on mast cell progenitor proliferation, survival, and suppression of Fc{varepsilon}RI expression.

cell biology↗

bioRxiv2018

Divergent effects of acute and prolonged interleukin 33 exposure onmast cell IgE-mediated functions

BackgroundEpithelial cytokines, including IL-33 and TSLP, have attracted interest because of their roles in chronic allergic inflammation-related conditions such as asthma. Mast cells are one of the major targets of IL-33, to which they respond by secreting cytokines. Most studies performed thus far have investigated the acute effects of IL-33 on mast cells.\n\nObjectiveThe objective of this study is to investigate how acute versus prolonged exposure of human mast cells to IL-33 and TSLP affects mediator synthesis and IgE-mediated activation.\n\nMethodsHuman lung mast cells (HLMCs), cord blood-derived mast cells (CBMCs), and the ROSA mast cell line were used for this study. Surface receptor expression and the levels of mediators were measured after treatment with IL-33 and/or TSLP.\n\nResultsIL-33 induced the acute release of cytokines. Prolonged exposure to IL-33 increased while TSLP reduced intracellular levels of tryptase. Acute IL-33 treatment strongly potentiated IgE-mediated activation. In contrast, four days of exposure to IL-33 decreased IgE-mediated activation, an effect that was accompanied by a reduction in Fc{varepsilon}RI expression.\n\nConclusion & Clinical RelevanceWe show that IL-33 plays dual roles for mast cell functions. The acute effect includes cytokine release and the potentiation of IgE-mediated degranulation, whereas prolonged exposure to IL-33 reduces IgE-mediated activation. We conclude that mast cells act quickly in response to the alarmin IL-33 to initiate an acute inflammatory response, whereas extended exposure to IL-33 during prolonged inflammation reduces IgE-mediated responses. This negative feedback effect suggests the presence of a novel IL-33 mediated regulatory pathway that modulates IgE-induced human mast cell responses.

immunology↗

bioRxiv2018

Single-cell analysis reveals the KIT D816V mutation in hematopoietic stem and progenitor cells in systemic mastocytosis

Background: Systemic mastocytosis (SM) is a hematological disease characterized by organ infiltration by neoplastic mast cells. Almost all SM patients have a mutation in the gene encoding the tyrosine kinase receptor KIT causing a D816V substitution and autoactivation of the receptor. Mast cells and CD34+ hematopoietic progenitors can carry the mutation, however, in which progenitor cell subset the mutation arises is unknown. We aimed to investigate the distribution of the D816V mutation in single mast cells and single hematopoietic stem and progenitor cells. Methods: Fluorescence-activated single-cell index sorting and D816V mutation assessment were applied to analyze mast cells and more than 10,000 CD34+ bone marrow progenitors across 10 hematopoietic progenitor subsets. In vitro assays verified cell-forming potential. Findings: We found that in SM 60-99% of the mast cells harbored the D816V mutation. Despite increased frequencies of mast cells in SM patients compared with control subjects, the hematopoietic progenitor subset frequencies were comparable. Nevertheless, the mutation could be detected throughout the hematopoietic landscape of SM patients, from hematopoietic stem cells to more lineage-primed progenitors. In addition, we demonstrate that Fc{varepsilon}RI+ bone marrow progenitors exhibit mast cell-forming potential, and we describe aberrant CD45RA expression on SM mast cells for the first time. Interpretation: The KIT D816V mutation arises in early hematopoietic stem and progenitor cells and the mutation frequency is approaching 100% in mature mast cells, which express the aberrant marker CD45RA.

immunology↗