Dataset Information

CXCR4^high megakaryocytes regulate host-defense immunity against bacterial pathogens.

ABSTRACT: Megakaryocytes (MKs) continuously produce platelets to support hemostasis and form a niche for hematopoietic stem cell maintenance in the bone marrow. MKs are also involved in inflammatory responses; however, the mechanism remains poorly understood. Using single-cell sequencing, we identified a CXCR4 highly expressed MK subpopulation, which exhibited both MK-specific and immune characteristics. CXCR4^high MKs interacted with myeloid cells to promote their migration and stimulate the bacterial phagocytosis of macrophages and neutrophils by producing TNFα and IL-6. CXCR4^high MKs were also capable of phagocytosis, processing, and presenting antigens to activate T cells. Furthermore, CXCR4^high MKs also egressed circulation and infiltrated into the spleen, liver, and lung upon bacterial infection. Ablation of MKs suppressed the innate immune response and T cell activation to impair the anti-bacterial effects in mice under the Listeria monocytogenes challenge. Using hematopoietic stem/progenitor cell lineage-tracing mouse lines, we show that CXCR4^high MKs were generated from infection-induced emergency megakaryopoiesis in response to bacterial infection. Overall, we identify the CXCR4^high MKs, which regulate host-defense immune response against bacterial infection.

SUBMITTER: Wang J

PROVIDER: S-EPMC9374440 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature

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CXCR4<sup>high</sup> megakaryocytes regulate host-defense immunity against bacterial pathogens.

Wang Jin J Xie Jiayi J Wang Daosong D Han Xue X Chen Minqi M Shi Guojun G Jiang Linjia L Zhao Meng M

eLife 20220729

Megakaryocytes (MKs) continuously produce platelets to support hemostasis and form a niche for hematopoietic stem cell maintenance in the bone marrow. MKs are also involved in inflammatory responses; however, the mechanism remains poorly understood. Using single-cell sequencing, we identified a CXCR4 highly expressed MK subpopulation, which exhibited both MK-specific and immune characteristics. CXCR4<sup>high</sup> MKs interacted with myeloid cells to promote their migration and stimulate the ba ...[more]

PMID: 35904250

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Project description:The humoral immune response to bacterial or fungal infections in Drosophila relies largely on a transcriptional response mediated by the Toll and Immune deficiency NF-κB pathways. Antimicrobial peptides are potent effectors of these pathways and allow the organism to attack invading pathogens. Dorsal-related Immune Factor (DIF), a transcription factor regulated by the Toll pathway, is required in the host defense against fungal and some Gram-positive bacterial infections. The Mediator complex is involved in the initiation of transcription of most RNA polymerase B (PolB)-dependent genes by forming a functional bridge between transcription factors bound to enhancer regions and the gene promoter region and then recruiting the PolB pre-initiation complex. Mediator is formed by several modules that each comprises several subunits. The Med17 subunit of the head module of Mediator has been shown to be required for the expression of Drosomycin, which encodes a potent antifungal peptide, by binding to DIF. Thus, Mediator is expected to mediate the host defense against pathogens controlled by the Toll pathway-dependent innate immune response. Here, we first focus on the Med31 subunit of the middle module of Mediator and find that it is required in host defense against Aspergillus fumigatus, Enterococcus faecalis, and injected but not topically-applied Metarhizium robertsii. Thus, host defense against M. robertsii requires Dif but not necessarily Med31 in the two distinct infection models. The induction of some Toll-pathway-dependent genes is decreased after a challenge of Med31 RNAi-silenced flies with either A. fumigatus or E. faecalis, while these flies exhibit normal phagocytosis and melanization. We have further tested most Mediator subunits using RNAi by monitoring their survival after challenges to several other microbial infections known to be fought off through DIF. We report that the host defense against specific pathogens involves a distinct set of Mediator subunits with only one subunit for C. glabrata or Erwinia carotovora carotovora, at least one for M. robertsii or a somewhat extended repertoire for A. fumigatus (at least eight subunits) and E. faecalis (eight subunits), with two subunits, Med6 and Med11 being required only against A. fumigatus. Med31 but not Med17 is required in fighting off injected M. robertsii conidia. Thus, the involvement of Mediator in Drosophila innate immunity is more complex than expected.

Dataset Information

CXCR4^high megakaryocytes regulate host-defense immunity against bacterial pathogens.

Publications

CXCR4<sup>high</sup> megakaryocytes regulate host-defense immunity against bacterial pathogens.

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Dataset Information

CXCR4high megakaryocytes regulate host-defense immunity against bacterial pathogens.

Publications

CXCR4<sup>high</sup> megakaryocytes regulate host-defense immunity against bacterial pathogens.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

CXCR4^high megakaryocytes regulate host-defense immunity against bacterial pathogens.