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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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2
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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: 1.0] [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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3
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Martin RA, Tate AT. Pleiotropy promotes the evolution of inducible immune responses in a model of host-pathogen coevolution. PLoS Comput Biol 2023; 19:e1010445. [PMID: 37022993 PMCID: PMC10079112 DOI: 10.1371/journal.pcbi.1010445] [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: 07/29/2022] [Accepted: 02/23/2023] [Indexed: 04/07/2023] Open
Abstract
Components of immune systems face significant selective pressure to efficiently use organismal resources, mitigate infection, and resist parasitic manipulation. A theoretically optimal immune defense balances investment in constitutive and inducible immune components depending on the kinds of parasites encountered, but genetic and dynamic constraints can force deviation away from theoretical optima. One such potential constraint is pleiotropy, the phenomenon where a single gene affects multiple phenotypes. Although pleiotropy can prevent or dramatically slow adaptive evolution, it is prevalent in the signaling networks that compose metazoan immune systems. We hypothesized that pleiotropy is maintained in immune signaling networks despite slowed adaptive evolution because it provides some other advantage, such as forcing network evolution to compensate in ways that increase host fitness during infection. To study the effects of pleiotropy on the evolution of immune signaling networks, we used an agent-based modeling approach to evolve a population of host immune systems infected by simultaneously co-evolving parasites. Four kinds of pleiotropic restrictions on evolvability were incorporated into the networks, and their evolutionary outcomes were compared to, and competed against, non-pleiotropic networks. As the networks evolved, we tracked several metrics of immune network complexity, relative investment in inducible and constitutive defenses, and features associated with the winners and losers of competitive simulations. Our results suggest non-pleiotropic networks evolve to deploy highly constitutive immune responses regardless of parasite prevalence, but some implementations of pleiotropy favor the evolution of highly inducible immunity. These inducible pleiotropic networks are no less fit than non-pleiotropic networks and can out-compete non-pleiotropic networks in competitive simulations. These provide a theoretical explanation for the prevalence of pleiotropic genes in immune systems and highlight a mechanism that could facilitate the evolution of inducible immune responses.
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Affiliation(s)
- Reese A. Martin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Initiative, 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 Initiative, Vanderbilt University, Nashville, Tennessee, United States of America
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4
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Lo LK, R R, Tewes LJ, Milutinović B, Müller C, Kurtz J. Immune Stimulation via Wounding Alters Chemical Profiles of Adult Tribolium castaneum. J Chem Ecol 2023; 49:46-58. [PMID: 36539674 PMCID: PMC9941273 DOI: 10.1007/s10886-022-01395-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 11/20/2022] [Accepted: 11/23/2022] [Indexed: 12/24/2022]
Abstract
Group-living individuals experience immense risk of disease transmission and parasite infection. In social and in some non-social insects, disease control with immunomodulation arises not only via individual immune defenses, but also via infochemicals such as contact cues and (defensive) volatiles to mount a group-level immunity. However, little is known about whether activation of the immune system elicits changes in chemical phenotypes, which may mediate these responses. We here asked whether individual immune experience resulting from wounding or injection of heat-killed Bacillus thuringiensis (priming) leads to changes in the chemical profiles of female and male adult red flour beetles, Tribolium castaneum, which are non-social but gregarious. We analyzed insect extracts using GC-FID to study the chemical composition of (1) cuticular hydrocarbons (CHCs) as candidates for the transfer of immunity-related information between individuals via contact, and (2) stink gland secretions, with analysis of benzoquinones as main active compounds regulating 'external immunity'. Despite a pronounced sexual dimorphism in CHC profiles, wounding stimulation led to similar profile changes in males and females with increases in the proportion of methyl-branched alkanes compared to naïve beetles. While changes in the overall secretion profiles were less pronounced, absolute amounts of benzoquinones were transiently elevated in wounded compared to naïve females. Responses to priming were insignificant in CHCs and secretions. We suggest that changes in different infochemicals after wounding may mediate immune status signaling in the context of both internal and external immune responses in groups of this non-social insect, thus showing parallels to social immunity.
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Affiliation(s)
- Lai Ka Lo
- grid.5949.10000 0001 2172 9288Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149 Münster, Germany
| | - Reshma R
- grid.5949.10000 0001 2172 9288Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149 Münster, Germany
| | - Lisa Johanna Tewes
- grid.7491.b0000 0001 0944 9128Department of Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - Barbara Milutinović
- grid.5949.10000 0001 2172 9288Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149 Münster, Germany
| | - Caroline Müller
- grid.7491.b0000 0001 0944 9128Department of Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany
| | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstr. 1, 48149, Münster, Germany.
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5
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Wale N, Duffy MA. The Use and Underuse of Model Systems in Infectious Disease Ecology and Evolutionary Biology. Am Nat 2021; 198:69-92. [PMID: 34143716 DOI: 10.1086/714595] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractEver since biologists began studying the ecology and evolution of infectious diseases (EEID), laboratory-based model systems have been important for developing and testing theory. Yet what EEID researchers mean by the term "model systems" and what they want from them is unclear. This uncertainty hinders our ability to maximally exploit these systems, identify knowledge gaps, and establish effective new model systems. Here, we borrow a definition of model systems from the biomolecular sciences to assess how EEID researchers are (and are not) using 10 key model systems. According to this definition, model systems in EEID are not being used to their fullest and, in fact, cannot even be considered model systems. Research using these systems consistently addresses only two of the three fundamental processes that underlie disease dynamics-transmission and disease, but not recovery. Furthermore, studies tend to focus on only a few scales of biological organization that matter for disease ecology and evolution. Moreover, the field lacks an infrastructure to perform comparative analyses. We aim to begin a discussion of what we want from model systems, which would further progress toward a thorough, holistic understanding of EEID.
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6
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Sheehan G, Margalit A, Sheehan D, Kavanagh K. Proteomic profiling of bacterial and fungal induced immune priming in Galleria mellonella larvae. JOURNAL OF INSECT PHYSIOLOGY 2021; 131:104213. [PMID: 33662378 DOI: 10.1016/j.jinsphys.2021.104213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 02/19/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Some insects display immunological priming as a result of elevated humoral and cellular responses which give enhanced survival against subsequent infection. The humoral immune response of Galleria mellonella larvae following pre-exposure to heat killed Staphylococcus aureus or Candida albicans cells was determined by quantitative mass spectrometry in order to assess the relationship between the humoral immune response and resistance to subsequent bacterial or fungal infection. Larvae pre-exposed to heat killed S. aureus showed increased resistance to subsequent bacterial and fungal infection. Larvae displayed an increased hemocyte density (14.08 ± 2.14 × 106 larva-1 (p < 0.05) compared to the PBS injected control [10.41 ± 1.67 × 106 larva-1]) and increased abundance of antimicrobial proteins (cecropin-D-like peptide (+22.23 fold), hdd11 (+12.61 fold) and prophenol oxidase activating enzyme 3 (+5.96 fold) in response to heat killed S. aureus. Larvae pre-exposed to heat killed C. albicans cells were resistant to subsequent fungal infection but not bacterial infection and showed a reduced hemocyte density (6.01 ± 1.63 × 106 larva-1 (p < 0.01) and increased abundance of hdd11 (+32.73 fold) and moricin-like peptide C1 (+16.76 fold). While immune priming is well recognised in G. mellonella larvae the results presented here indicate distinct differences in the response of larvae following exposure to heat killed bacterial and fungal cells.
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Affiliation(s)
- Gerard Sheehan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Anatte Margalit
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - David Sheehan
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Kevin Kavanagh
- Department of Biology, Maynooth University, Maynooth, Co. Kildare, Ireland.
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7
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Wanelik KM, Begon M, Arriero E, Bradley JE, Friberg IM, Jackson JA, Taylor CH, Paterson S. Transcriptome-wide analysis reveals different categories of response to a standardised immune challenge in a wild rodent. Sci Rep 2020; 10:7444. [PMID: 32366957 PMCID: PMC7198573 DOI: 10.1038/s41598-020-64307-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 04/14/2020] [Indexed: 11/09/2022] Open
Abstract
Individuals vary in their immune response and, as a result, some are more susceptible to infectious disease than others. Little is known about the nature of this individual variation in natural populations, or which components of immune pathways are most responsible, but defining this underlying landscape of variation is an essential first step to understanding the drivers of this variation and, ultimately, predicting the outcome of infection. We describe transcriptome-wide variation in response to a standardised immune challenge in wild field voles. We find that genes (hereafter 'markers') can be categorised into a limited number of types. For the majority of markers, the response of an individual is dependent on its baseline expression level, with significant enrichment in this category for conventional immune pathways. Another, moderately sized, category contains markers for which the responses of different individuals are also variable but independent of their baseline expression levels. This category lacks any enrichment for conventional immune pathways. We further identify markers which display particularly high individual variability in response, and could be used as markers of immune response in larger studies. Our work shows how a standardised challenge performed on a natural population can reveal the patterns of natural variation in immune response.
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Affiliation(s)
- Klara M Wanelik
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom.
| | - Mike Begon
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Elena Arriero
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom.,Department of Biodiversity, Ecology and Evolution, University Complutense of Madrid, Madrid, Spain
| | - Janette E Bradley
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Ida M Friberg
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| | - Joseph A Jackson
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
| | | | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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8
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Jent D, Perry A, Critchlow J, Tate AT. Natural variation in the contribution of microbial density to inducible immune dynamics. Mol Ecol 2019; 28:5360-5372. [PMID: 31674070 DOI: 10.1111/mec.15293] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/13/2019] [Accepted: 10/21/2019] [Indexed: 12/23/2022]
Abstract
Immune responses evolve to balance the benefits of microbial killing against the costs of autoimmunity and energetic resource use. Models that explore the evolution of optimal immune responses generally include a term for constitutive immunity, or the level of immunological investment prior to microbial exposure, and for inducible immunity, or investment in immune function after microbial challenge. However, studies rarely consider the functional form of inducible immune responses with respect to microbial density, despite the theoretical dependence of immune system evolution on microbe- versus immune-mediated damage to the host. In this study, we analyse antimicrobial peptide (AMP) gene expression from seven wild-caught flour beetle populations (Tribolium spp.) during acute infection with the virulent bacteria Bacillus thuringiensis (Bt) and Photorhabdus luminescens (P.lum) to demonstrate that inducible immune responses mediated by the humoral IMD pathway exhibit natural variation in both microbe density-dependent and independent temporal dynamics. Beetle populations that exhibited greater AMP expression sensitivity to Bt density were also more likely to die from infection, while populations that exhibited higher microbe density-independent AMP expression were more likely to survive P. luminescens infection. Reduction in pathway signalling efficiency through RNAi-mediated knockdown of the imd gene reduced the magnitude of both microbe-independent and dependent responses and reduced host resistance to Bt growth, but had no net effect on host survival. This study provides a framework for understanding natural variation in the flexibility of investment in inducible immune responses and should inform theory on the contribution of nonequilibrium host-microbe dynamics to immune system evolution.
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Affiliation(s)
- Derrick Jent
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Abby Perry
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Justin Critchlow
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
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9
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Strauss AT, Hite JL, Civitello DJ, Shocket MS, Cáceres CE, Hall SR. Genotypic variation in parasite avoidance behaviour and other mechanistic, nonlinear components of transmission. Proc Biol Sci 2019; 286:20192164. [PMID: 31744438 DOI: 10.1098/rspb.2019.2164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Traditional epidemiological models assume that transmission increases proportionally to the density of parasites. However, empirical data frequently contradict this assumption. General yet mechanistic models can explain why transmission depends nonlinearly on parasite density and thereby identify potential defensive strategies of hosts. For example, hosts could decrease their exposure rates at higher parasite densities (via behavioural avoidance) or decrease their per-parasite susceptibility when encountering more parasites (e.g. via stronger immune responses). To illustrate, we fitted mechanistic transmission models to 19 genotypes of Daphnia dentifera hosts over gradients of the trophically acquired parasite, Metschnikowia bicuspidata. Exposure rate (foraging, F) frequently decreased with parasite density (Z), and per-parasite susceptibility (U) frequently decreased with parasite encounters (F × Z). Consequently, infection rates (F × U × Z) often peaked at intermediate parasite densities. Moreover, host genotypes varied substantially in these responses. Exposure rates remained constant for some genotypes but decreased sensitively with parasite density for others (up to 78%). Furthermore, genotypes with more sensitive foraging/exposure also foraged faster in the absence of parasites (suggesting 'fast and sensitive' versus 'slow and steady' strategies). These relationships suggest that high densities of parasites can inhibit transmission by decreasing exposure rates and/or per-parasite susceptibility, and identify several intriguing axes for the evolution of host defence.
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Affiliation(s)
| | - Jessica L Hite
- Department of Biology, Indiana University, Bloomington, IN 47401, USA
| | | | - Marta S Shocket
- Department of Biology, Indiana University, Bloomington, IN 47401, USA
| | - Carla E Cáceres
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Spencer R Hall
- Department of Biology, Indiana University, Bloomington, IN 47401, USA
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10
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Yu J, Wang H, Yue X, Liu B. Dynamic immune and metabolism response of clam Meretrix petechialis to Vibrio challenge revealed by a time series of transcriptome analysis. FISH & SHELLFISH IMMUNOLOGY 2019; 94:17-26. [PMID: 31465871 DOI: 10.1016/j.fsi.2019.08.057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/20/2019] [Accepted: 08/24/2019] [Indexed: 05/27/2023]
Abstract
Meretrix petechialis is an important commercial aquaculture species in China. During the clam culture period, mass mortality events often occurred due to the Vibrio infection. In this paper, M. petechialis were challenged with Vibrio parahaemolyticus immersion to simulate a natural infection, and the infection process were divided into four phases including latency, prodrome, onset and recovery phases based on the clam mortality data. Then, the dynamic response of clams to Vibrio infection at different infection phases were investigated by transcriptome analysis. A total of 38,067 differentially expressed genes (DEGs) were identified at different infection phases. DEG annotations showed that immune-related and metabolism-related signaling pathways were enriched, indicating that immune defense and metabolism process play key roles during bacterial infection. Three kinds of expression pattern were classified by cluster analysis, including U-shape, L-shape and inverted V-shape. Anabolism and cellular growth proliferation related signaling pathways were repressed (long-lasting or transient) during bacterial infection. However, the immune related signaling pathways with different immune functions showed induction expression or repression expression against bacterial infection, which indicated that immune system take different strategies against bacterial infection. Furthermore, some signaling pathways such as PI3K-Akt signaling pathway both involved in immune defense and cell metabolism. This study provides a sight that the dynamic immunity and metabolic responses may be integrated to improve the host survival and shift more energy for immune defense.
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Affiliation(s)
- Jiajia Yu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hongxia Wang
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China
| | - Xin Yue
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China
| | - Baozhong Liu
- CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
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11
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Chambers MC, Jacobson E, Khalil S, Lazzaro BP. Consequences of chronic bacterial infection in Drosophila melanogaster. PLoS One 2019; 14:e0224440. [PMID: 31648237 PMCID: PMC6812774 DOI: 10.1371/journal.pone.0224440] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/14/2019] [Indexed: 11/25/2022] Open
Abstract
Even when successfully surviving an infection, a host often fails to eliminate a pathogen completely and may sustain substantial pathogen burden for the remainder of its life. Using systemic bacterial infection in Drosophila melanogaster, we characterize chronic infection by three bacterial species from different genera - Providencia rettgeri, Serratia marcescens, and Enterococcus faecalis–following inoculation with a range of doses. To assess the consequences of these chronic infections, we determined the expression of antimicrobial peptide genes, survival of secondary infection, and starvation resistance after one week of infection. While higher infectious doses unsurprisingly lead to higher risk of death, they also result in higher chronic bacterial loads among the survivors for all three infections. All three chronic infections caused significantly elevated expression of antimicrobial peptide genes at one week post-infection and provided generalized protection again secondary bacterial infection. Only P. rettgeri infection significantly influenced resistance to starvation, with persistently infected flies dying more quickly under starvation conditions relative to controls. These results suggest that there is potentially a generalized mechanism of protection against secondary infection, but that other impacts on host physiology may depend on the specific pathogen. We propose that chronic infections in D. melanogaster could be a valuable tool for studying tolerance of infection, including impacts on host physiology and behavior.
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Affiliation(s)
- Moria Cairns Chambers
- Department of Entomology, Cornell University, Ithaca, New York, United States of America
- Department of Biology, Bucknell University, Lewisburg, PA, United States of America
- * E-mail:
| | - Eliana Jacobson
- Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Sarah Khalil
- Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Brian P. Lazzaro
- Department of Entomology, Cornell University, Ithaca, New York, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, United States of America
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12
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Ferro K, Peuß R, Yang W, Rosenstiel P, Schulenburg H, Kurtz J. Experimental evolution of immunological specificity. Proc Natl Acad Sci U S A 2019; 116:20598-20604. [PMID: 31548373 PMCID: PMC6789748 DOI: 10.1073/pnas.1904828116] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Memory and specificity are hallmarks of the adaptive immune system. Contrary to prior belief, innate immune systems can also provide forms of immune memory, such as immune priming in invertebrates and trained immunity in vertebrates. Immune priming can even be specific but differs remarkably in cellular and molecular functionality from the well-studied adaptive immune system of vertebrates. To date, it is unknown whether and how the level of specificity in immune priming can adapt during evolution in response to natural selection. We tested the evolution of priming specificity in an invertebrate model, the beetle Tribolium castaneum Using controlled evolution experiments, we selected beetles for either specific or unspecific immune priming toward the bacteria Pseudomonas fluorescens, Lactococcus lactis, and 4 strains of the entomopathogen Bacillus thuringiensis After 14 generations of host selection, specificity of priming was not universally higher in the lines selected for specificity, but rather depended on the bacterium used for priming and challenge. The insect pathogen B. thuringiensis induced the strongest priming effect. Differences between the evolved populations were mirrored in the transcriptomic response, revealing involvement of immune, metabolic, and transcription-modifying genes. Finally, we demonstrate that the induction strength of a set of differentially expressed immune genes predicts the survival probability of the evolved lines upon infection. We conclude that high specificity of immune priming can evolve rapidly for certain bacteria, most likely due to changes in the regulation of immune genes.
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Affiliation(s)
- Kevin Ferro
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
- Department of Entomology, University of Arizona, Tucson, AZ 85704
| | - Robert Peuß
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Wentao Yang
- Zoological Institute, Kiel University, 24118 Kiel, Germany
| | - Philip Rosenstiel
- Institute of Clinical Molecular Biology, Kiel University, 24105 Kiel, Germany
| | - Hinrich Schulenburg
- Zoological Institute, Kiel University, 24118 Kiel, Germany
- Max Planck Institute for Evolutionary Biology, 24306 Plön, Germany
| | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany;
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13
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Khan I, Prakash A, Agashe D. Pathogen susceptibility and fitness costs explain variation in immune priming across natural populations of flour beetles. J Anim Ecol 2019; 88:1332-1342. [DOI: 10.1111/1365-2656.13030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/10/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Imroze Khan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research GKVK Bangalore India
- Ashoka University Sonepat Rai India
| | - Arun Prakash
- National Centre for Biological Sciences, Tata Institute of Fundamental Research GKVK Bangalore India
| | - Deepa Agashe
- National Centre for Biological Sciences, Tata Institute of Fundamental Research GKVK Bangalore India
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Abstract
A central challenge in the fields of evolutionary immunology and disease ecology is to understand the causes and consequences of natural variation in host susceptibility to infectious diseases. As hosts progress from birth to death in the wild, they are exposed to a wide variety of microorganisms that influence their physical condition, immune system maturation, and susceptibility to concurrent and future infection. A central challenge in the fields of evolutionary immunology and disease ecology is to understand the causes and consequences of natural variation in host susceptibility to infectious diseases. As hosts progress from birth to death in the wild, they are exposed to a wide variety of microorganisms that influence their physical condition, immune system maturation, and susceptibility to concurrent and future infection. Thus, multiple exposures to the same or different microbes can be important environmental drivers of host immunological variation and immune priming. In this perspective, I discuss parasite infracommunity interactions and their imprint on host immunity in space and time. I further consider feedbacks from parasite community dynamics within individual hosts on the transmission of disease at higher levels of biological organization and highlight the promise of systems biology approaches, using flour beetles as an example, for studying the role of multiple infections on immunological variation in wild populations.
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15
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Kutzer MAM, Kurtz J, Armitage SAO. A multi-faceted approach testing the effects of previous bacterial exposure on resistance and tolerance. J Anim Ecol 2019; 88:566-578. [PMID: 30697699 PMCID: PMC6487967 DOI: 10.1111/1365-2656.12953] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 12/03/2018] [Indexed: 01/03/2023]
Abstract
Hosts can alter their strategy towards pathogens during their lifetime; that is, they can show phenotypic plasticity in immunity or life history. Immune priming is one such example, where a previous encounter with a pathogen confers enhanced protection upon secondary challenge, resulting in reduced pathogen load (i.e., resistance) and improved host survival. However, an initial encounter might also enhance tolerance, particularly to less virulent opportunistic pathogens that establish persistent infections. In this scenario, individuals are better able to reduce the negative fecundity consequences that result from a high pathogen burden. Finally, previous exposure may also lead to life‐history adjustments, such as terminal investment into reproduction. Using different Drosophila melanogaster host genotypes and two bacterial pathogens, Lactococcus lactis and Pseudomonas entomophila, we tested whether previous exposure results in resistance or tolerance and whether it modifies immune gene expression during an acute‐phase infection (one day post‐challenge). We then asked whether previous pathogen exposure affects chronic‐phase pathogen persistence and longer‐term survival (28 days post‐challenge). We predicted that previous exposure would increase host resistance to an early stage bacterial infection while it might come at a cost to host fecundity tolerance. We reasoned that resistance would be due in part to stronger immune gene expression after challenge. We expected that previous exposure would improve long‐term survival, that it would reduce infection persistence, and we expected to find genetic variation in these responses. We found that previous exposure to P. entomophila weakened host resistance to a second infection independent of genotype and had no effect on immune gene expression. Fecundity tolerance showed genotypic variation but was not influenced by previous exposure. However, L. lactis persisted as a chronic infection, whereas survivors cleared the more pathogenic P. entomophila infection. To our knowledge, this is the first study that addresses host tolerance to bacteria in relation to previous exposure, taking a multi‐faceted approach to address the topic. Our results suggest that previous exposure comes with transient costs to resistance during the early stage of infection in this host–pathogen system and that infection persistence may be bacterium‐specific.
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Affiliation(s)
- Megan A M Kutzer
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.,IST Austria, Klosterneuburg, Austria
| | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Sophie A O Armitage
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.,Institute of Biology, Freie Universität Berlin, Berlin, Germany
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16
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Troha K, Im JH, Revah J, Lazzaro BP, Buchon N. Comparative transcriptomics reveals CrebA as a novel regulator of infection tolerance in D. melanogaster. PLoS Pathog 2018; 14:e1006847. [PMID: 29394281 PMCID: PMC5812652 DOI: 10.1371/journal.ppat.1006847] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 02/14/2018] [Accepted: 01/01/2018] [Indexed: 12/15/2022] Open
Abstract
Host responses to infection encompass many processes in addition to activation of the immune system, including metabolic adaptations, stress responses, tissue repair, and other reactions. The response to bacterial infection in Drosophila melanogaster has been classically described in studies that focused on the immune response elicited by a small set of largely avirulent microbes. Thus, we have surprisingly limited knowledge of responses to infection that are outside the canonical immune response, of how the response to pathogenic infection differs from that to avirulent bacteria, or even of how generic the response to various microbes is and what regulates that core response. In this study, we addressed these questions by profiling the D. melanogaster transcriptomic response to 10 bacteria that span the spectrum of virulence. We found that each bacterium triggers a unique transcriptional response, with distinct genes making up to one third of the response elicited by highly virulent bacteria. We also identified a core set of 252 genes that are differentially expressed in response to the majority of bacteria tested. Among these, we determined that the transcription factor CrebA is a novel regulator of infection tolerance. Knock-down of CrebA significantly increased mortality from microbial infection without any concomitant change in bacterial number. Upon infection, CrebA is upregulated by both the Toll and Imd pathways in the fat body, where it is required to induce the expression of secretory pathway genes. Loss of CrebA during infection triggered endoplasmic reticulum (ER) stress and activated the unfolded protein response (UPR), which contributed to infection-induced mortality. Altogether, our study reveals essential features of the response to bacterial infection and elucidates the function of a novel regulator of infection tolerance.
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Affiliation(s)
- Katia Troha
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Joo Hyun Im
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Jonathan Revah
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Brian P. Lazzaro
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America
| | - Nicolas Buchon
- Cornell Institute of Host-Microbe Interactions and Disease, Department of Entomology, Cornell University, Ithaca, New York, United States of America
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17
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Ferro K, Ferro D, Corrà F, Bakiu R, Santovito G, Kurtz J. Cu,Zn Superoxide Dismutase Genes in Tribolium castaneum: Evolution, Molecular Characterisation, and Gene Expression during Immune Priming. Front Immunol 2017; 8:1811. [PMID: 29375546 PMCID: PMC5763126 DOI: 10.3389/fimmu.2017.01811] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Accepted: 12/01/2017] [Indexed: 12/11/2022] Open
Abstract
The production of reactive oxygen species (ROS) is a normal consequence of the aerobic cell metabolism. Despite their high and potentially detrimental reactivity with various biomolecules, the endogenous production of ROS is a vital part of physiological, immunological, and molecular processes that contribute to fitness. The role of ROS in host-parasite interactions is frequently defined by their contribution to innate immunity as effectors, promoting parasite death during infections. In vertebrates, ROS and antioxidant system enzymes, such as superoxide dismutase (SOD) are also involved in acquired immune memory, where they are responsible for T-cell signalling, activation, proliferation, and viability. Based on recent findings, ROS are now also assumed to play a role in immune priming, i.e., a form of memory in invertebrates. In this study, the potential involvement of Cu,Zn SODs in immunity of the red flour beetle Tribolium castaneum is described for the first time, applying an approach that combines an in silico gene characterisation with an in vivo immune priming experiment using the Gram-positive entomopathogen Bacillus thuringiensis. We identified an unusually high number of three different transcripts for extracellular SOD and found that priming leads to a fine-tuned modulation of SOD expression, highlighting the potential of physiological co-adaptations for immune phenotypes.
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Affiliation(s)
- Kevin Ferro
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Diana Ferro
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | | | - Rigers Bakiu
- Department of Aquaculture and Fisheries, Faculty of Agriculture and Environment, Agricultural University of Tirana, Tirana, Albania
| | | | - Joachim Kurtz
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
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