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Hixson B, Chen R, Buchon N. Innate immunity in Aedes mosquitoes: from pathogen resistance to shaping the microbiota. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230063. [PMID: 38497256 PMCID: PMC10945403 DOI: 10.1098/rstb.2023.0063] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 10/12/2023] [Indexed: 03/19/2024] Open
Abstract
Discussions of host-microbe interactions in mosquito vectors are frequently dominated by a focus on the human pathogens they transmit (e.g. Plasmodium parasites and arboviruses). Underlying the interactions between a vector and its transmissible pathogens, however, is the physiology of an insect living and interacting with a world of bacteria and fungi including commensals, mutualists and primary and opportunistic pathogens. Here we review what is known about the bacteria and fungi associated with mosquitoes, with an emphasis on the members of the Aedes genus. We explore the reciprocal effects of microbe on mosquito, and mosquito on microbe. We analyse the roles of bacterial and fungal symbionts in mosquito development, their effects on vector competence, and their potential uses as biocontrol agents and vectors for paratransgenesis. We explore the compartments of the mosquito gut, uncovering the regionalization of immune effectors and modulators, which create the zones of resistance and immune tolerance with which the mosquito host controls and corrals its microbial symbionts. We examine the anatomical patterning of basally expressed antimicrobial peptides. Finally, we review the relationships between inducible antimicrobial peptides and canonical immune signalling pathways, comparing and contrasting current knowledge on each pathway in mosquitoes to the model insect Drosophila melanogaster. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.
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Affiliation(s)
- Bretta Hixson
- Department of Entomology, Cornell University College of Agriculture and Life Sciences, Ithaca, 14853, NY, USA
| | - Robin Chen
- Department of Entomology, Cornell University College of Agriculture and Life Sciences, Ithaca, 14853, NY, USA
| | - Nicolas Buchon
- Department of Entomology, Cornell University College of Agriculture and Life Sciences, Ithaca, 14853, NY, USA
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Hixson B, Huot L, Morejon B, Yang X, Nagy P, Michel K, Buchon N. The transcriptional response in mosquitoes distinguishes between fungi and bacteria but not Gram types. BMC Genomics 2024; 25:353. [PMID: 38594632 PMCID: PMC11003161 DOI: 10.1186/s12864-024-10153-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 02/22/2024] [Indexed: 04/11/2024] Open
Abstract
Mosquitoes are prolific vectors of human pathogens, therefore a clear and accurate understanding of the organization of their antimicrobial defenses is crucial for informing the development of transmission control strategies. The canonical infection response in insects, as described in the insect model Drosophila melanogaster, is pathogen type-dependent, with distinct stereotypical responses to Gram-negative bacteria and Gram-positive bacteria/fungi mediated by the activation of the Imd and Toll pathways, respectively. To determine whether this pathogen-specific discrimination is shared by mosquitoes, we used RNAseq to capture the genome-wide transcriptional response of Aedes aegypti and Anopheles gambiae (s.l.) to systemic infection with Gram-negative bacteria, Gram-positive bacteria, yeasts, and filamentous fungi, as well as challenge with heat-killed Gram-negative, Gram-positive, and fungal pathogens. From the resulting data, we found that Ae. aegypti and An. gambiae both mount a core response to all categories of infection, and this response is highly conserved between the two species with respect to both function and orthology. When we compared the transcriptomes of mosquitoes infected with different types of bacteria, we observed that the intensity of the transcriptional response was correlated with both the virulence and growth rate of the infecting pathogen. Exhaustive comparisons of the transcriptomes of Gram-negative-challenged versus Gram-positive-challenged mosquitoes yielded no difference in either species. In Ae. aegypti, however, we identified transcriptional signatures specific to bacterial infection and to fungal infection. The bacterial infection response was dominated by the expression of defensins and cecropins, while the fungal infection response included the disproportionate upregulation of an uncharacterized family of glycine-rich proteins. These signatures were also observed in Ae. aegypti challenged with heat-killed bacteria and fungi, indicating that this species can discriminate between molecular patterns that are specific to bacteria and to fungi.
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Affiliation(s)
- Bretta Hixson
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Louise Huot
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Bianca Morejon
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Xiaowei Yang
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
- Current address: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute for Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Peter Nagy
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY, 14853, USA
| | - Kristin Michel
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Nicolas Buchon
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, NY, 14853, USA.
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Alvarenga PH, Alves E Silva TL, Suzuki M, Nardone G, Cecilio P, Vega-Rodriguez J, Ribeiro JMC, Andersen JF. Comprehensive Proteomics Analysis of the Hemolymph Composition of Sugar-Fed Aedes aegypti Female and Male Mosquitoes. J Proteome Res 2024; 23:1471-1487. [PMID: 38576391 DOI: 10.1021/acs.jproteome.3c00918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2024]
Abstract
In arthropods, hemolymph carries immune cells and solubilizes and transports nutrients, hormones, and other molecules that are involved in diverse physiological processes including immunity, metabolism, and reproduction. However, despite such physiological importance, little is known about its composition. We applied mass spectrometry-based label-free quantification approaches to study the proteome of hemolymph perfused from sugar-fed female and male Aedes aegypti mosquitoes. A total of 1403 proteins were identified, out of which 447 of them were predicted to be extracellular. In both sexes, almost half of these extracellular proteins were predicted to be involved in defense/immune response, and their relative abundances (based on their intensity-based absolute quantification, iBAQ) were 37.9 and 33.2%, respectively. Interestingly, among them, 102 serine proteases/serine protease-homologues were identified, with almost half of them containing CLIP regulatory domains. Moreover, proteins belonging to families classically described as chemoreceptors, such as odorant-binding proteins (OBPs) and chemosensory proteins (CSPs), were also highly abundant in the hemolymph of both sexes. Our data provide a comprehensive catalogue of A. aegypti hemolymph basal protein content, revealing numerous unexplored targets for future research on mosquito physiology and disease transmission. It also provides a reference for future studies on the effect of blood meal and infection on hemolymph composition.
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Affiliation(s)
- Patricia H Alvarenga
- Vector Biology Section, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Thiago Luiz Alves E Silva
- Molecular Parasitology and Entomology Unit, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Motoshi Suzuki
- Protein and Chemistry Section, Research Technologies Branch, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Glenn Nardone
- Protein and Chemistry Section, Research Technologies Branch, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Pedro Cecilio
- Vector Biology Section, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Joel Vega-Rodriguez
- Molecular Parasitology and Entomology Unit, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
| | - Jose M C Ribeiro
- Vector Biology Section, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
| | - John F Andersen
- Vector Biology Section, Laboratory of Malaria and Vector Research, NIH-NIAID, Rockville, Maryland 20852, United States
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Critchlow JT, Prakash A, Zhong KY, Tate AT. Mapping the functional form of the trade-off between infection resistance and reproductive fitness under dysregulated immune signaling. PLoS Pathog 2024; 20:e1012049. [PMID: 38408106 PMCID: PMC10919860 DOI: 10.1371/journal.ppat.1012049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 03/07/2024] [Accepted: 02/15/2024] [Indexed: 02/28/2024] Open
Abstract
Immune responses benefit organismal fitness by clearing parasites but also exact costs associated with immunopathology and energetic investment. Hosts manage these costs by tightly regulating the induction of immune signaling to curtail excessive responses and restore homeostasis. Despite the theoretical importance of turning off the immune response to mitigate these costs, experimentally connecting variation in the negative regulation of immune responses to organismal fitness remains a frontier in evolutionary immunology. In this study, we used a dose-response approach to manipulate the RNAi-mediated knockdown efficiency of cactus (IκBα), a central regulator of Toll pathway signal transduction in flour beetles (Tribolium castaneum). By titrating cactus activity across four distinct levels, we derived the shape of the relationship between immune response investment and traits associated with host fitness, including infection susceptibility, lifespan, fecundity, body mass, and gut homeostasis. Cactus knock-down increased the overall magnitude of inducible immune responses and delayed their resolution in a dsRNA dose-dependent manner, promoting survival and resistance following bacterial infection. However, these benefits were counterbalanced by dsRNA dose-dependent costs to lifespan, fecundity, body mass, and gut integrity. Our results allowed us to move beyond the qualitative identification of a trade-off between immune investment and fitness to actually derive its functional form. This approach paves the way to quantitatively compare the evolution and impact of distinct regulatory elements on life-history trade-offs and fitness, filling a crucial gap in our conceptual and theoretical models of immune signaling network evolution and the maintenance of natural variation in immune systems.
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Affiliation(s)
- Justin T Critchlow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Arun Prakash
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Katherine Y Zhong
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Institute, Vanderbilt University, Nashville, Tennessee, United States of America
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Critchlow JT, Prakash A, Zhong KY, Tate AT. Mapping the functional form of the trade-off between infection resistance and reproductive fitness under dysregulated immune signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552815. [PMID: 37645726 PMCID: PMC10461925 DOI: 10.1101/2023.08.10.552815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Immune responses benefit organismal fitness by clearing parasites but also exact costs associated with immunopathology and energetic investment. Hosts manage these costs by tightly regulating the induction of immune signaling to curtail excessive responses and restore homeostasis. Despite the theoretical importance of turning off the immune response to mitigate these costs, experimentally connecting variation in the negative regulation of immune responses to organismal fitness remains a frontier in evolutionary immunology. In this study, we used a dose-response approach to manipulate the RNAi-mediated knockdown efficiency of cactus (IκBα), a central regulator of Toll pathway signal transduction in flour beetles (Tribolium castaneum). By titrating cactus activity along a continuous gradient, we derived the shape of the relationship between immune response investment and traits associated with host fitness, including infection susceptibility, lifespan, fecundity, body mass, and gut homeostasis. Cactus knock-down increased the overall magintude of inducible immune responses and delayed their resolution in a dsRNA dose-dependent manner, promoting survival and resistance following bacterial infection. However, these benefits were counterbalanced by dsRNA dose-dependent costs to lifespan, fecundity, body mass, and gut integrity. Our results allowed us to move beyond the qualitative identification of a trade-off between immune investment and fitness to actually derive its functional form. This approach paves the way to quantitatively compare the evolution and impact of distinct regulatory elements on life-history trade-offs and fitness, filling a crucial gap in our conceptual and theoretical models of immune signaling network evolution and the maintenance of natural variation in immune systems.
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Affiliation(s)
- Justin T. Critchlow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Arun Prakash
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Katherine Y. Zhong
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ann T. Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Institute, Vanderbilt University, Nashville, Tennessee, United States of America
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Hixson B, Huot L, Morejon B, Yang X, Nagy P, Michel K, Buchon N. The transcriptional response in mosquitoes distinguishes between fungi and bacteria but not Gram types. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.26.550663. [PMID: 37546902 PMCID: PMC10402080 DOI: 10.1101/2023.07.26.550663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Mosquitoes are prolific vectors of human pathogens; a clear and accurate understanding of the organization of their antimicrobial defenses is crucial for informing the development of transmission control strategies. The canonical infection response in insects, as described in the insect model Drosophila melanogaster , is pathogen type-dependent, with distinct stereotypical responses to Gram-negative bacteria and Gram-positive bacteria/fungi mediated by the activation of the Imd and Toll pathways, respectively. To determine whether this pathogen-specific discrimination is shared by mosquitoes, we used RNAseq to capture the genome-wide transcriptional response of Aedes aegypti and Anopheles gambiae ( s.l. ) to systemic infection with Gram-negative bacteria, Gram-positive bacteria, yeasts, and filamentous fungi, as well as challenge with heat-killed Gram-negative, Gram-positive, and fungal pathogens. From the resulting data, we found that Ae. aegypti and An. gambiae both mount a core response to all categories of infection, and this response is highly conserved between the two species with respect to both function and orthology. When we compared the transcriptomes of mosquitoes infected with different types of bacteria, we observed that the intensity of the transcriptional response was correlated with both the virulence and growth rate of the infecting pathogen. Exhaustive comparisons of the transcriptomes of Gram-negative-challenged versus Gram-positive-challenged mosquitoes yielded no difference in either species. In Ae. aegypti , however, we identified transcriptional signatures specific to bacterial infection and to fungal infection. The bacterial infection response was dominated by the expression of defensins and cecropins, while the fungal infection response included the disproportionate upregulation of an uncharacterized family of glycine-rich proteins. These signatures were also observed in Ae. aegypti challenged with heat-killed bacteria and fungi, indicating that this species can discriminate between molecular patterns that are specific to bacteria and to fungi.
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Orchard I, Al-Dailami AN, Leyria J, Lange AB. Malpighian tubules of Rhodnius prolixus: More than post-prandial diuresis. FRONTIERS IN INSECT SCIENCE 2023; 3:1167889. [PMID: 38469518 PMCID: PMC10926411 DOI: 10.3389/finsc.2023.1167889] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 03/14/2023] [Indexed: 03/13/2024]
Abstract
Rhodnius prolixus, a major vector of Chagas disease, may be considered the model upon which the foundations of insect physiology and biochemistry were built. It is an obligate blood feeder in which the blood meal triggers growth, development and reproduction. The blood meal also triggers a post-prandial diuresis to maintain osmotic homeostasis. In R. prolixus, as with other insects, the Malpighian tubules play a critical role in this diuresis, and much has been learned about diuresis in R. prolixus, and in other model insects. But the post-genomic era has brought new insights, identifying functions quite apart from diuresis for Malpighian tubules. Indeed, microarrays, transcriptomes, and proteomics have revealed the major roles that Malpighian tubules play in immunity, detoxification, pesticide resistance, and in tolerance to overall stress. This is particularly relevant to R. prolixus since gorging on blood creates several challenges in addition to osmotic balance. Xenobiotics may be present in the blood or toxins may be produced by metabolism of blood; and these must be neutralized and excreted. These processes have not been well described at the molecular level for Malpighian tubules of R. prolixus. This paper will review the involvement of Malpighian tubules in immunity and detoxification, identifying new aspects for Malpighian tubule physiology of R. prolixus by virtue of a transcriptome analysis. The transcriptome analysis indicates the potential of Malpighian tubules of R. prolixus to mount a robust innate immune response, and to contribute to antioxidant production and heme detoxification.
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Affiliation(s)
- Ian Orchard
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
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