scholarly journals A parasitoid wasp of Drosophila employs preemptive and reactive strategies to deplete its host’s blood cells

2021 ◽  
Vol 17 (5) ◽  
pp. e1009615
Author(s):  
Johnny R. Ramroop ◽  
Mary Ellen Heavner ◽  
Zubaidul H. Razzak ◽  
Shubha Govind
Keyword(s):  
Cellular Immunity ◽  
Blood Cells ◽  
Parasitoid Wasp ◽  
Lymph Gland ◽  
Parasite Development ◽  
Hematopoietic Organ ◽  
Immune Quiescence ◽  
Endocytic Machinery ◽  
The Face ◽  
Genetically Manipulated

The wasps Leptopilina heterotoma parasitize and ingest their Drosophila hosts. They produce extracellular vesicles (EVs) in the venom that are packed with proteins, some of which perform immune suppressive functions. EV interactions with blood cells of host larvae are linked to hematopoietic depletion, immune suppression, and parasite success. But how EVs disperse within the host, enter and kill hematopoietic cells are not well understood. Using an antibody marker for L. heterotoma EVs, we show that these parasite-derived structures are readily distributed within the hosts’ hemolymphatic system. EVs converge around the tightly clustered cells of the posterior signaling center (PSC) of the larval lymph gland, a small hematopoietic organ in Drosophila. The PSC serves as a source of developmental signals in naïve animals. In wasp-infected animals, the PSC directs the differentiation of lymph gland progenitors into lamellocytes. These lamellocytes are needed to encapsulate the wasp egg and block parasite development. We found that L. heterotoma infection disassembles the PSC and PSC cells disperse into the disintegrating lymph gland lobes. Genetically manipulated PSC-less lymph glands remain non-responsive and largely intact in the face of L. heterotoma infection. We also show that the larval lymph gland progenitors use the endocytic machinery to internalize EVs. Once inside, L. heterotoma EVs damage the Rab7- and LAMP-positive late endocytic and phagolysosomal compartments. Rab5 maintains hematopoietic and immune quiescence as Rab5 knockdown results in hematopoietic over-proliferation and ectopic lamellocyte differentiation. Thus, both aspects of anti-parasite immunity, i.e., (a) phagocytosis of the wasp’s immune-suppressive EVs, and (b) progenitor differentiation for wasp egg encapsulation reside in the lymph gland. These results help explain why the lymph gland is specifically and precisely targeted for destruction. The parasite’s simultaneous and multipronged approach to block cellular immunity not only eliminates blood cells, but also tactically blocks the genetic programming needed for supplementary hematopoietic differentiation necessary for host success. In addition to its known functions in hematopoiesis, our results highlight a previously unrecognized phagocytic role of the lymph gland in cellular immunity. EV-mediated virulence strategies described for L. heterotoma are likely to be shared by other parasitoid wasps; their understanding can improve the design and development of novel therapeutics and biopesticides as well as help protect biodiversity.

scholarly journals A parasitoid wasp of Drosophila employs preemptive and reactive strategies to deplete its host’s blood cells

2021 ◽  
Author(s):  
Johnny R. Ramroop ◽  
Mary Ellen Heavner ◽  
Zubaidul H. Razzak ◽  
Shubha Govind
Keyword(s):  
Extracellular Vesicles ◽  
Cellular Immunity ◽  
Blood Cells ◽  
Insect Pests ◽  
Lymph Gland ◽  
Parasite Development ◽  
Parasitoid Wasps ◽  
Parasitic Wasps ◽  
Hematopoietic Organ ◽  
Leptopilina Heterotoma

AbstractThe wasps Leptopilina heterotoma parasitize and ingest their Drosophila hosts. They produce extracellular vesicles (EVs) in the venom that are packed with proteins, some of which perform immune suppressive functions. EV interactions with blood cells of host larvae are linked to hematopoietic depletion, immune suppression, and parasite success. But how EVs disperse within the host, enter and kill hematopoietic cells are not well understood. Using an antibody marker for L. heterotoma EVs, we show that these parasite-derived structures are readily distributed within the hosts’ hemolymphatic system. EVs converge around the tightly clustered cells of the posterior signaling center (PSC) of the larval lymph gland, a small hematopoietic organ in Drosophila. The PSC serves as a source of developmental signals in naïve animals. In wasp-infected animals, the PSC directs the differentiation of lymph gland progenitors into lamellocytes. These lamellocytes are needed to encapsulate the wasp egg and block parasite development. We found that L. heterotoma infection disassembles the PSC and PSC cells disperse into the disintegrating lymph gland lobes. Genetically manipulated PSC-less lymph glands remain non-responsive and largely intact in the face of L. heterotoma infection. We also show that the larval lymph gland progenitors use the endocytic machinery to internalize EVs. Once inside, L. heterotoma EVs damage the Rab7- and LAMP1-positive late endocytic and phagolysosomal compartments. Rab5 maintains hematopoietic and immune quiescence as Rab5 knockdown results in hematopoietic over-proliferation and ectopic lamellocyte differentiation. Thus, both aspects of anti-parasite immunity, i.e., (a) phagocytosis of the wasp’s immune-suppressive EVs, and (b) progenitor differentiation for wasp egg encapsulation reside in the lymph gland. These results help explain why the lymph gland is specifically and precisely targeted for destruction. The parasite’s simultaneous and multipronged approach to block cellular immunity not only eliminates blood cells, but also tactically blocks the genetic programming needed for supplementary hematopoietic differentiation necessary for host success. In addition to its known functions in hematopoiesis, our results highlight a previously unrecognized phagocytic role of the lymph gland in cellular immunity. EV-mediated virulence strategies described for L. heterotoma are likely to be shared by other parasitoid wasps; their understanding can improve the design and development of novel therapeutics and biopesticides as well as help protect biodiversity.Author summaryParasitoid wasps serve as biological control agents of agricultural insect pests and are worthy of study. Many parasitic wasps develop inside their hosts to emerge as free-living adults. To overcome the resistance of their hosts, parasitic wasps use varied and ingenious strategies such as mimicry, evasion, bioactive venom, virus-like particles, viruses, and extracellular vesicles (EVs). We describe the effects of a unique class of EVs containing virulence proteins and produced in the venom of wasps that parasitize fruit flies of Drosophila species. EVs from Leptopilina heterotoma are widely distributed throughout the Drosophila hosts’ circulatory system after infection. They enter and kill macrophages by destroying the very same subcellular machinery that facilitates their uptake. An important protein in this process, Rab5, is needed to maintain the identity of the macrophage; when Rab5 function is reduced, macrophages turn into a different cell type called lamellocytes. Activities in the EVs can eliminate lamellocytes as well. EVs also interfere with the hosts’ genetic program that promotes lamellocyte differentiation needed to block parasite development. Thus, wasps combine specific preemptive and reactive strategies to deplete their hosts of the very cells that would otherwise sequester and kill them. These findings have applied value in agricultural pest control and medical therapeutics.

scholarly journals Drosophila as a Model to Study Cellular Communication Between the Hematopoietic Niche and Blood Progenitors Under Homeostatic Conditions and in Response to an Immune Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Ismaël Morin-Poulard ◽  
Yushun Tian ◽  
Nathalie Vanzo ◽  
Michèle Crozatier
Keyword(s):  
Blood Cell ◽  
Progenitor Cells ◽  
Blood Cells ◽  
Molecular Mechanisms ◽  
Vascular System ◽  
Lymph Gland ◽  
Hematopoietic Progenitors ◽  
Hematopoietic Stem ◽  
Hematopoietic Organ ◽  
Immune Stress

In adult mammals, blood cells are formed from hematopoietic stem progenitor cells, which are controlled by a complex cellular microenvironment called “niche”. Drosophila melanogaster is a powerful model organism to decipher the mechanisms controlling hematopoiesis, due both to its limited number of blood cell lineages and to the conservation of genes and signaling pathways throughout bilaterian evolution. Insect blood cells or hemocytes are similar to the mammalian myeloid lineage that ensures innate immunity functions. Like in vertebrates, two waves of hematopoiesis occur in Drosophila. The first wave takes place during embryogenesis. The second wave occurs at larval stages, where two distinct hematopoietic sites are identified: subcuticular hematopoietic pockets and a specialized hematopoietic organ called the lymph gland. In both sites, hematopoiesis is regulated by distinct niches. In hematopoietic pockets, sensory neurons of the peripheral nervous system provide a microenvironment that promotes embryonic hemocyte expansion and differentiation. In the lymph gland blood cells are produced from hematopoietic progenitors. A small cluster of cells called Posterior Signaling Centre (PSC) and the vascular system, along which the lymph gland develops, act collectively as a niche, under homeostatic conditions, to control the balance between maintenance and differentiation of lymph gland progenitors. In response to an immune stress such as wasp parasitism, lymph gland hematopoiesis is drastically modified and shifts towards emergency hematopoiesis, leading to increased progenitor proliferation and their differentiation into lamellocyte, a specific blood cell type which will neutralize the parasite. The PSC is essential to control this emergency response. In this review, we summarize Drosophila cellular and molecular mechanisms involved in the communication between the niche and hematopoietic progenitors, both under homeostatic and stress conditions. Finally, we discuss similarities between mechanisms by which niches regulate hematopoietic stem/progenitor cells in Drosophila and mammals.

scholarly journals Pvr expression regulators in equilibrium signal control and maintenance of Drosophila blood progenitors

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Bama Charan Mondal ◽  
Jiwon Shim ◽  
Cory J Evans ◽  
Utpal Banerjee
Keyword(s):  
Drosophila Melanogaster ◽  
Blood Cells ◽  
Lymph Gland ◽  
Genetic Screen ◽  
Signal Control ◽  
Vegf Receptor ◽  
Interacting Protein ◽  
Hematopoietic Development ◽  
New Genes ◽  
Progenitor Maintenance

Blood progenitors within the lymph gland, a larval organ that supports hematopoiesis in Drosophila melanogaster, are maintained by integrating signals emanating from niche-like cells and those from differentiating blood cells. We term the signal from differentiating cells the ‘equilibrium signal’ in order to distinguish it from the ‘niche signal’. Earlier we showed that equilibrium signaling utilizes Pvr (the Drosophila PDGF/VEGF receptor), STAT92E, and adenosine deaminase-related growth factor A (ADGF-A) (<xref ref-type="bibr" rid="bib43">Mondal et al., 2011</xref>). Little is known about how this signal initiates during hematopoietic development. To identify new genes involved in lymph gland blood progenitor maintenance, particularly those involved in equilibrium signaling, we performed a genetic screen that identified bip1 (bric à brac interacting protein 1) and Nucleoporin 98 (Nup98) as additional regulators of the equilibrium signal. We show that the products of these genes along with the Bip1-interacting protein RpS8 (Ribosomal protein S8) are required for the proper expression of Pvr.

scholarly journals Parasitoid wasp venom SERCA regulatesDrosophilacalcium levels and inhibits cellular immunity

2013 ◽  
Vol 110 (23) ◽  
pp. 9427-9432 ◽  
Author(s):  
Nathan T. Mortimer ◽  
Jeremy Goecks ◽  
Balint Z. Kacsoh ◽  
James A. Mobley ◽  
Gregory J. Bowersock ◽  
...  
Keyword(s):  
Cellular Immunity ◽  
Parasitoid Wasp ◽  
Wasp Venom

scholarly journals Protection against malaria in mice is induced by blood stage–arresting histamine-releasing factor (HRF)–deficient parasites

2016 ◽  
Vol 213 (8) ◽  
pp. 1419-1428 ◽  
Author(s):  
Claudia Demarta-Gatsi ◽  
Leanna Smith ◽  
Sabine Thiberge ◽  
Roger Peronet ◽  
Pierre-Henri Commere ◽  
...  
Keyword(s):  
Immune Responses ◽  
Plasmodium Berghei ◽  
Blood Cells ◽  
Housekeeping Genes ◽  
Blood Stage ◽  
Parasite Development ◽  
Rodent Models ◽  
Cell Responses ◽  
Blood Stage Malaria

Although most vaccines against blood stage malaria in development today use subunit preparations, live attenuated parasites confer significantly broader and more lasting protection. In recent years, Plasmodium genetically attenuated parasites (GAPs) have been generated in rodent models that cause self-resolving blood stage infections and induce strong protection. All such GAPs generated so far bear mutations in housekeeping genes important for parasite development in red blood cells. In this study, using a Plasmodium berghei model compatible with tracking anti–blood stage immune responses over time, we report a novel blood stage GAP that lacks a secreted factor related to histamine-releasing factor (HRF). Lack of HRF causes an IL-6 increase, which boosts T and B cell responses to resolve infection and leave a cross-stage, cross-species, and lasting immunity. Mutant-induced protection involves a combination of antiparasite IgG2c antibodies and FcγR+ CD11b+ cell phagocytes, especially neutrophils, which are sufficient to confer protection. This immune-boosting GAP highlights an important role of opsonized parasite-mediated phagocytosis, which may be central to protection induced by all self-resolving blood stage GAP infections.

scholarly journals Headcase is a Repressor of Lamellocyte Fate in Drosophila melanogaster

Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 173 ◽  
Author(s):  
Gergely I. B. Varga ◽  
Gábor Csordás ◽  
Gyöngyi Cinege ◽  
Ferenc Jankovics ◽  
Rita Sinka ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Differentiation ◽  
Blood Cell ◽  
Cell Fate ◽  
Blood Cells ◽  
Mutational Analysis ◽  
Genetic Interaction ◽  
Lymph Gland ◽  
Loss Of Function ◽  
Hematopoietic Stem

Due to the evolutionary conservation of the regulation of hematopoiesis, Drosophila provides an excellent model organism to study blood cell differentiation and hematopoietic stem cell (HSC) maintenance. The larvae of Drosophila melanogaster respond to immune induction with the production of special effector blood cells, the lamellocytes, which encapsulate and subsequently kill the invader. Lamellocytes differentiate as a result of a concerted action of all three hematopoietic compartments of the larva: the lymph gland, the circulating hemocytes, and the sessile tissue. Within the lymph gland, the communication of the functional zones, the maintenance of HSC fate, and the differentiation of effector blood cells are regulated by a complex network of signaling pathways. Applying gene conversion, mutational analysis, and a candidate based genetic interaction screen, we investigated the role of Headcase (Hdc), the homolog of the tumor suppressor HECA in the hematopoiesis of Drosophila. We found that naive loss-of-function hdc mutant larvae produce lamellocytes, showing that Hdc has a repressive role in effector blood cell differentiation. We demonstrate that hdc genetically interacts with the Hedgehog and the Decapentaplegic pathways in the hematopoietic niche of the lymph gland. By adding further details to the model of blood cell fate regulation in the lymph gland of the larva, our findings contribute to the better understanding of HSC maintenance.

scholarly journals Single-cell transcriptome maps of myeloid blood cell lineages in Drosophila

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Bumsik Cho ◽  
Sang-Ho Yoon ◽  
Daewon Lee ◽  
Ferdinand Koranteng ◽  
Sudhir Gopal Tattikota ◽  
...  
Keyword(s):  
Single Cell ◽  
Lymph Gland ◽  
Developmental Trajectory ◽  
Hematopoietic Organ ◽  
Cell Lineages ◽  
Cellular Immune Responses ◽  
Cell Transcriptome ◽  
Cellular Immune ◽  
Single Cell Transcriptome ◽  
Crystal Cells

Abstract The Drosophila lymph gland, the larval hematopoietic organ comprised of prohemocytes and mature hemocytes, has been a valuable model for understanding mechanisms underlying hematopoiesis and immunity. Three types of mature hemocytes have been characterized in the lymph gland: plasmatocytes, lamellocytes, and crystal cells, which are analogous to vertebrate myeloid cells, yet molecular underpinnings of the lymph gland hemocytes have been less investigated. Here, we use single-cell RNA sequencing to comprehensively analyze heterogeneity of developing hemocytes in the lymph gland, and discover previously undescribed hemocyte types including adipohemocytes, stem-like prohemocytes, and intermediate prohemocytes. Additionally, we identify the developmental trajectory of hemocytes during normal development as well as the emergence of the lamellocyte lineage following active cellular immunity caused by wasp infestation. Finally, we establish similarities and differences between embryonically derived- and larval lymph gland hemocytes. Altogether, our study provides detailed insights into the hemocyte development and cellular immune responses at single-cell resolution.

scholarly journals Quantification of labile heme in live malaria parasites using a genetically encoded biosensor

2017 ◽  
Vol 114 (11) ◽  
pp. E2068-E2076 ◽  
Author(s):  
James R. Abshire ◽  
Christopher J. Rowlands ◽  
Suresh M. Ganesan ◽  
Peter T. C. So ◽  
Jacquin C. Niles
Keyword(s):  
Blood Cells ◽  
Antimalarial Activity ◽  
Cellular Damage ◽  
Malarial Parasite ◽  
Redox Activity ◽  
Parasite Development ◽  
Heme Binding ◽  
Environmental Perturbations ◽  
Hemoglobin Degradation ◽  
Relevant Component

Heme is ubiquitous, yet relatively little is known about the maintenance of labile pools of this cofactor, which likely ensures its timely bioavailability for proper cellular function. Quantitative analysis of labile heme is of fundamental importance to understanding how nature preserves access to the diverse chemistry heme enables, while minimizing cellular damage caused by its redox activity. Here, we have developed and characterized a protein-based sensor that undergoes fluorescence quenching upon heme binding. By genetically encoding this sensor in the human malarial parasite, Plasmodium falciparum, we have quantified cytosolic labile heme levels in intact, blood-stage parasites. Our findings indicate that a labile heme pool (∼1.6 µM) is stably maintained throughout parasite development within red blood cells, even during a period coincident with extensive hemoglobin degradation by the parasite. We also find that the heme-binding antimalarial drug chloroquine specifically increases labile cytosolic heme, indicative of dysregulation of this homeostatic pool that may be a relevant component of the antimalarial activity of this compound class. We propose that use of this technology under various environmental perturbations in P. falciparum can yield quantitative insights into fundamental heme biology.

scholarly journals Reactive oxygen species-dependent Toll/NF-κB activation in the Drosophila hematopoietic niche confers resistance to wasp parasitism

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Isabelle Louradour ◽  
Anurag Sharma ◽  
Ismael Morin-Poulard ◽  
Manon Letourneau ◽  
Alain Vincent ◽  
...  
Keyword(s):  
Regulatory Network ◽  
Lymph Gland ◽  
Cell Renewal ◽  
Egfr Signaling ◽  
Hematopoietic Stem ◽  
Hematopoietic Organ ◽  
Immune Stress ◽  
Pathway Activation ◽  
Co Activation ◽  
Open Question

Hematopoietic stem/progenitor cells in the adult mammalian bone marrow ensure blood cell renewal. Their cellular microenvironment, called ‘niche’, regulates hematopoiesis both under homeostatic and immune stress conditions. In the Drosophila hematopoietic organ, the lymph gland, the posterior signaling center (PSC) acts as a niche to regulate the hematopoietic response to immune stress such as wasp parasitism. This response relies on the differentiation of lamellocytes, a cryptic cell type, dedicated to pathogen encapsulation and killing. Here, we establish that Toll/NF-κB pathway activation in the PSC in response to wasp parasitism non-cell autonomously induces the lymph gland immune response. Our data further establish a regulatory network where co-activation of Toll/NF-κB and EGFR signaling by ROS levels in the PSC/niche controls lymph gland hematopoiesis under parasitism. Whether a similar regulatory network operates in mammals to control emergency hematopoiesis is an open question.

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