1
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Zhang Y, Iino Y, Schafer WR. Behavioral plasticity. Genetics 2024:iyae105. [PMID: 39158469 DOI: 10.1093/genetics/iyae105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 06/10/2024] [Indexed: 08/20/2024] Open
Abstract
Behavioral plasticity allows animals to modulate their behavior based on experience and environmental conditions. Caenorhabditis elegans exhibits experience-dependent changes in its behavioral responses to various modalities of sensory cues, including odorants, salts, temperature, and mechanical stimulations. Most of these forms of behavioral plasticity, such as adaptation, habituation, associative learning, and imprinting, are shared with other animals. The C. elegans nervous system is considerably tractable for experimental studies-its function can be characterized and manipulated with molecular genetic methods, its activity can be visualized and analyzed with imaging approaches, and the connectivity of its relatively small number of neurons are well described. Therefore, C. elegans provides an opportunity to study molecular, neuronal, and circuit mechanisms underlying behavioral plasticity that are either conserved in other animals or unique to this species. These findings reveal insights into how the nervous system interacts with the environmental cues to generate behavioral changes with adaptive values.
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Affiliation(s)
- Yun Zhang
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
| | - Yuichi Iino
- Department of Biological Sciences, University of Tokyo, Tokyo 113-0032, Japan
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, Cambridgeshire CB2 0QH, UK
- Department of Biology, KU Leuven, 3000 Leuven, Belgium
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2
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Kwon S, Park KS, Yoon KH. Regulator of Lipid Metabolism NHR-49 Mediates Pathogen Avoidance through Precise Control of Neuronal Activity. Cells 2024; 13:978. [PMID: 38891110 PMCID: PMC11172349 DOI: 10.3390/cells13110978] [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: 04/05/2024] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024] Open
Abstract
Precise control of neuronal activity is crucial for the proper functioning of neurons. How lipid homeostasis contributes to neuronal activity and how much of it is regulated by cells autonomously is unclear. In this study, we discovered that absence of the lipid regulator nhr-49, a functional ortholog of the peroxisome proliferator-activated receptor (PPAR) in Caenorhabditis elegans, resulted in defective pathogen avoidance behavior against Pseudomonas aeruginosa (PA14). Functional NHR-49 was required in the neurons, and more specifically, in a set of oxygen-sensing body cavity neurons, URX, AQR, and PQR. We found that lowering the neuronal activity of the body cavity neurons improved avoidance in nhr-49 mutants. Calcium imaging in URX neurons showed that nhr-49 mutants displayed longer-lasting calcium transients in response to an O2 upshift, suggesting that excess neuronal activity leads to avoidance defects. Cell-specific rescue of NHR-49 in the body cavity neurons was sufficient to improve pathogen avoidance, as well as URX neuron calcium kinetics. Supplementation with oleic acid also improved avoidance behavior and URX calcium kinetics, suggesting that the defective calcium response in the neuron is due to lipid dysfunction. These findings highlight the role of cell-autonomous lipid regulation in neuronal physiology and immune behavior.
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Affiliation(s)
- Saebom Kwon
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea;
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea;
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
| | - Kyoung-hye Yoon
- Mitohormesis Research Center, Yonsei University Wonju College of Medicine, Wonju 26426, Republic of Korea
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3
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Schmidt AK, Schwartzkopf CM, Pourtois JD, Burgener EB, Faith DR, Joyce A, Lamma T, Kumar G, Bollyky PL, Secor PR. Targeted deletion of Pf prophages from diverse Pseudomonas aeruginosa isolates has differential impacts on quorum sensing and virulence traits. J Bacteriol 2024; 206:e0040223. [PMID: 38687034 PMCID: PMC11112994 DOI: 10.1128/jb.00402-23] [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: 11/19/2023] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that commonly causes medical hardware, wound, and respiratory infections. Temperate filamentous Pf phages that infect P. aeruginosa impact numerous virulence phenotypes. Most work on Pf phages has focused on Pf4 and its host P. aeruginosa PAO1. Expanding from Pf4 and PAO1, this study explores diverse Pf phages infecting P. aeruginosa clinical isolates. We describe a simple technique targeting the Pf lysogeny maintenance gene, pflM (PA0718), that enables the effective elimination of Pf prophages from diverse P. aeruginosa hosts. The pflM gene shows diversity among different Pf phage isolates; however, all examined pflM alleles encode the DUF5447 domain. We demonstrate that pflM deletion results in prophage excision but not replication, leading to total prophage loss, indicating a role for lysis/lysogeny decisions for the DUF5447 domain. This study also assesses the effects different Pf phages have on host quorum sensing, biofilm formation, pigment production, and virulence against the bacterivorous nematode Caenorhabditis elegans. We find that Pf phages have strain-specific impacts on quorum sensing and biofilm formation, but nearly all suppress pigment production and increase C. elegans avoidance behavior. Collectively, this research not only introduces a valuable tool for Pf prophage elimination from diverse P. aeruginosa isolates but also advances our understanding of the complex relationship between P. aeruginosa and filamentous Pf phages.IMPORTANCEPseudomonas aeruginosa is an opportunistic bacterial pathogen that is frequently infected by filamentous Pf phages (viruses) that integrate into its chromosome, affecting behavior. Although prior work has focused on Pf4 and PAO1, this study investigates diverse Pf in clinical isolates. A simple method targeting the deletion of the Pf lysogeny maintenance gene pflM (PA0718) effectively eliminates Pf prophages from clinical isolates. The research evaluates the impact Pf prophages have on bacterial quorum sensing, biofilm formation, and virulence phenotypes. This work introduces a valuable tool to eliminate Pf prophages from clinical isolates and advances our understanding of P. aeruginosa and filamentous Pf phage interactions.
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Affiliation(s)
- Amelia K. Schmidt
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | | | - Julie D. Pourtois
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Elizabeth B. Burgener
- Division of Pediatric Pulmonology and Sleep Medicine, Children’s Hospital of Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
- Center for Excellence in Pulmonary Biology, Department of Pediatrics, Stanford University, Stanford, California, USA
| | - Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Alex Joyce
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Tyrza Lamma
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Geetha Kumar
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Paul L. Bollyky
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
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4
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Singh A, Luallen RJ. Understanding the factors regulating host-microbiome interactions using Caenorhabditis elegans. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230059. [PMID: 38497260 PMCID: PMC10945399 DOI: 10.1098/rstb.2023.0059] [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: 08/16/2023] [Accepted: 01/01/2024] [Indexed: 03/19/2024] Open
Abstract
The Human Microbiome Project was a research programme that successfully identified associations between microbial species and healthy or diseased individuals. However, a major challenge identified was the absence of model systems for studying host-microbiome interactions, which would increase our capacity to uncover molecular interactions, understand organ-specificity and discover new microbiome-altering health interventions. Caenorhabditis elegans has been a pioneering model organism for over 70 years but was largely studied in the absence of a microbiome. Recently, ecological sampling of wild nematodes has uncovered a large amount of natural genetic diversity as well as a slew of associated microbiota. The field has now explored the interactions of C. elegans with its associated gut microbiome, a defined and non-random microbial community, highlighting its suitability for dissecting host-microbiome interactions. This core microbiome is being used to study the impact of host genetics, age and stressors on microbiome composition. Furthermore, single microbiome species are being used to dissect molecular interactions between microbes and the animal gut. Being amenable to health altering genetic and non-genetic interventions, C. elegans has emerged as a promising system to generate and test new hypotheses regarding host-microbiome interactions, with the potential to uncover novel paradigms relevant to other systems. 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)
- Anupama Singh
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Robert J. Luallen
- Department of Biology, San Diego State University, San Diego, CA 92182, USA
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5
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Lei M, Tan Y, Tu H, Tan W. Neuronal basis and diverse mechanisms of pathogen avoidance in Caenorhabditis elegans. Front Immunol 2024; 15:1353747. [PMID: 38751431 PMCID: PMC11094273 DOI: 10.3389/fimmu.2024.1353747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 04/22/2024] [Indexed: 05/18/2024] Open
Abstract
Pathogen avoidance behaviour has been observed across animal taxa as a vital host-microbe interaction mechanism. The nematode Caenorhabditis elegans has evolved multiple diverse mechanisms for pathogen avoidance under natural selection pressure. We summarise the current knowledge of the stimuli that trigger pathogen avoidance, including alterations in aerotaxis, intestinal bloating, and metabolites. We then survey the neural circuits involved in pathogen avoidance, transgenerational epigenetic inheritance of pathogen avoidance, signalling crosstalk between pathogen avoidance and innate immunity, and C. elegans avoidance of non-Pseudomonas bacteria. In this review, we highlight the latest advances in understanding host-microbe interactions and the gut-brain axis.
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Affiliation(s)
- Ming Lei
- Academy of Medical Engineering and Translational Medicine (AMT), Tianjin University, Tianjin, China
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, Hunan, China
- The Key Laboratory of Zhejiang Province for Aptamers and Theranostics, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, China
| | - Yanheng Tan
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, Hunan, China
| | - Haijun Tu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, Hunan, China
| | - Weihong Tan
- Academy of Medical Engineering and Translational Medicine (AMT), Tianjin University, Tianjin, China
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan University, Changsha, Hunan, China
- The Key Laboratory of Zhejiang Province for Aptamers and Theranostics, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, China
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6
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Otarigho B, Butts AF, Aballay A. Neuronal NPR-15 modulates molecular and behavioral immune responses via the amphid sensory neuron-intestinal axis in C. elegans. eLife 2024; 12:RP90051. [PMID: 38446031 PMCID: PMC10942643 DOI: 10.7554/elife.90051] [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: 03/07/2024] Open
Abstract
The survival of hosts during infections relies on their ability to mount effective molecular and behavioral immune responses. Despite extensive research on these defense strategies in various species, including the model organism Caenorhabditis elegans, the neural mechanisms underlying their interaction remain poorly understood. Previous studies have highlighted the role of neural G-protein-coupled receptors (GPCRs) in regulating both immunity and pathogen avoidance, which is particularly dependent on aerotaxis. To address this knowledge gap, we conducted a screen of mutants in neuropeptide receptor family genes. We found that loss-of-function mutations in npr-15 activated immunity while suppressing pathogen avoidance behavior. Through further analysis, NPR-15 was found to regulate immunity by modulating the activity of key transcription factors, namely GATA/ELT-2 and TFEB/HLH-30. Surprisingly, the lack of pathogen avoidance of npr-15 mutant animals was not influenced by oxygen levels. Moreover, our studies revealed that the amphid sensory neuron ASJ is involved in mediating the immune and behavioral responses orchestrated by NPR-15. Additionally, NPR-15 was found to regulate avoidance behavior via the TRPM (transient receptor potential melastatin) gene, GON-2, which may sense the intestinal distension caused by bacterial colonization to elicit pathogen avoidance. Our study contributes to a broader understanding of host defense strategies and mechanisms underlining the interaction between molecular and behavioral immune responses.
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Affiliation(s)
- Benson Otarigho
- Department of Genetics, The University of Texas MD Anderson Cancer CenterHoustonUnited States
| | - Anna Frances Butts
- Department of Genetics, The University of Texas MD Anderson Cancer CenterHoustonUnited States
| | - Alejandro Aballay
- Department of Genetics, The University of Texas MD Anderson Cancer CenterHoustonUnited States
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealthHoustonUnited States
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7
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Tse-Kang S, Wani KA, Peterson ND, Page A, Pukkila-Worley R. Activation of intestinal immunity by pathogen effector-triggered aggregation of lysosomal TIR-1/SARM1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.04.569946. [PMID: 38106043 PMCID: PMC10723332 DOI: 10.1101/2023.12.04.569946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
TIR-domain proteins with enzymatic activity are essential for immunity in plants, animals, and bacteria. However, it is not known how these proteins function in pathogen sensing in animals. We discovered that a TIR-domain protein (TIR-1/SARM1) is strategically expressed on the membranes of a lysosomal sub-compartment, which enables intestinal epithelial cells in the nematode C. elegans to survey for pathogen effector-triggered host damage. We showed that a redox active virulence effector secreted by the bacterial pathogen Pseudomonas aeruginosa alkalinized and condensed a specific subset of lysosomes by inducing intracellular oxidative stress. Concentration of TIR-1/SARM1 on the surface of these organelles triggered its multimerization, which engages its intrinsic NADase activity, to activate the p38 innate immune pathway and protect the host against microbial intoxication. Thus, lysosomal TIR-1/SARM1 is a sensor for oxidative stress induced by pathogenic bacteria to activate metazoan intestinal immunity.
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8
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Tran TD, Luallen RJ. An organismal understanding of C. elegans innate immune responses, from pathogen recognition to multigenerational resistance. Semin Cell Dev Biol 2024; 154:77-84. [PMID: 36966075 PMCID: PMC10517082 DOI: 10.1016/j.semcdb.2023.03.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 03/05/2023] [Accepted: 03/14/2023] [Indexed: 03/27/2023]
Abstract
The nematode Caenorhabditis elegans has been a model for studying infection since the early 2000s and many major discoveries have been made regarding its innate immune responses. C. elegans has been found to utilize some key conserved aspects of immune responses and signaling, but new interesting features of innate immunity have also been discovered in the organism that might have broader implications in higher eukaryotes such as mammals. Some of the distinctive features of C. elegans innate immunity involve the mechanisms this bacterivore uses to detect infection and mount specific immune responses to different pathogens, despite lacking putative orthologs of many important innate immune components, including cellular immunity, the inflammasome, complement, or melanization. Even when orthologs of known immune factors exist, there appears to be an absence of canonical functions, most notably the lack of pattern recognition by its sole Toll-like receptor. Instead, recent research suggests that C. elegans senses infection by specific pathogens through contextual information, including unique products produced by the pathogen or infection-induced disruption of host physiology, similar to the proposed detection of patterns of pathogenesis in mammalian systems. Interestingly, C. elegans can also transfer information of past infection to their progeny, providing robust protection for their offspring in face of persisting pathogens, in part through the RNAi pathway as well as potential new mechanisms that remain to be elucidated. Altogether, some of these strategies employed by C. elegans share key conceptual features with vertebrate adaptive immunity, as the animal can differentiate specific microbial features, as well as propagate a form of immune memory to their offspring.
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Affiliation(s)
- Tuan D Tran
- Department of Biology San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA
| | - Robert J Luallen
- Department of Biology San Diego State University, 5500 Campanile Dr., San Diego, CA 92182, USA.
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9
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Nair T, Weathers BA, Stuhr NL, Nhan JD, Curran SP. Serotonin deficiency from constitutive SKN-1 activation drives pathogen apathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.10.579755. [PMID: 38405962 PMCID: PMC10888766 DOI: 10.1101/2024.02.10.579755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
When an organism encounters a pathogen, the host innate immune system activates to defend against pathogen colonization and toxic xenobiotics produced. C. elegans employ multiple defense systems to ensure survival when exposed to Pseudomonas aeruginosa including activation of the cytoprotective transcription factor SKN-1/NRF2. Although wildtype C. elegans quickly learn to avoid pathogens, here we describe a peculiar apathy-like behavior towards PA14 in animals with constitutive activation of SKN-1, whereby animals choose not to leave and continue to feed on the pathogen even when a non-pathogenic and healthspan-promoting food option is available. Although lacking the urgency to escape the infectious environment, animals with constitutive SKN-1 activity are not oblivious to the presence of the pathogen and display the typical pathogen-induced intestinal distension and eventual demise. SKN-1 activation, specifically in neurons and intestinal tissues, orchestrates a unique transcriptional program which leads to defects in serotonin signaling that is required from both neurons and non-neuronal tissues. Serotonin depletion from SKN-1 activation limits pathogen defense capacity, drives the pathogen-associated apathy behaviors and induces a synthetic sensitivity to selective serotonin reuptake inhibitors. Taken together, our work reveals new insights into how animals perceive environmental pathogens and subsequently alter behavior and cellular programs to promote survival. KEY POINTS Identify an apathy-like behavioral response for pathogens resulting from the constitutive activation of the cytoprotective transcription factor SKN-1.Uncover the obligate role for serotonin synthesis in both neuronal and non-neuronal cells for the apathy-like state and ability of serotonin treatment to restore normal behaviors.Characterize the timing and tissue specificity of SKN-1 nuclear localization in neurons and intestinal cells in response to pathogen exposure.Define the unique and context-specific transcriptional signatures of animals with constitutive SKN-1 activation when exposed to pathogenic environments.Reveal necessity for both neuronal and non-neuronal serotonin signaling in host survival from pathogen infection.
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10
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Otarigho B, Butts AF, Aballay A. Neuronal NPR-15 modulates molecular and behavioral immune responses via the amphid sensory neuron-intestinal axis in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.07.27.550570. [PMID: 37546751 PMCID: PMC10402133 DOI: 10.1101/2023.07.27.550570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The survival of hosts during infections relies on their ability to mount effective molecular and behavioral immune responses. Despite extensive research on these defense strategies in various species, including the model organism Caenorhabditis elegans, the neural mechanisms underlying their interaction remain poorly understood. Previous studies have highlighted the role of neural G protein-coupled receptors (GPCRs) in regulating both immunity and pathogen avoidance, which is particularly dependent on aerotaxis. To address this knowledge gap, we conducted a screen of mutants in neuropeptide receptor family genes. We found that loss-of-function mutations in npr-15 activated immunity while suppressing pathogen avoidance behavior. Through further analysis, NPR-15 was found to regulate immunity by modulating the activity of key transcription factors, namely GATA/ELT-2 and TFEB/HLH-30. Surprisingly, the lack of pathogen avoidance of npr-15 mutant animals was not influenced by oxygen levels. Moreover, our studies revealed that the amphid sensory neuron ASJ is involved in mediating the immune and behavioral responses orchestrated by NPR-15. Additionally, NPR-15 was found to regulate avoidance behavior via the TRPM gene, GON-2, which may sense the intestinal distension caused by bacterial colonization to elicit pathogen avoidance. Our study contributes to a broader understanding of host defense strategies and mechanisms underlining the interaction between molecular and behavioral immune responses.
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Affiliation(s)
- Benson Otarigho
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Anna Frances Butts
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Alejandro Aballay
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, TX
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11
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Schmidt AK, Schwartzkopf CM, Pourtois JD, Burgener E, Faith DR, Joyce A, Lamma T, Kumar G, Bollyky PL, Secor PR. Targeted deletion of Pf prophages from diverse Pseudomonas aeruginosa isolates impacts quorum sensing and virulence traits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.19.567716. [PMID: 38014273 PMCID: PMC10680813 DOI: 10.1101/2023.11.19.567716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that commonly causes medical hardware, wound, and respiratory infections. Temperate filamentous Pf phages that infect P. aeruginosa impact numerous bacterial virulence phenotypes. Most work on Pf phages has focused on strain Pf4 and its host P. aeruginosa PAO1. Expanding from Pf4 and PAO1, this study explores diverse Pf strains infecting P. aeruginosa clinical isolates. We describe a simple technique targeting the Pf lysogeny maintenance gene, pflM (PA0718), that enables the effective elimination of Pf prophages from diverse P. aeruginosa hosts. This study also assesses the effects different Pf phages have on host quorum sensing, biofilm formation, virulence factor production, and virulence. Collectively, this research not only introduces a valuable tool for Pf prophage elimination from diverse P. aeruginosa isolates, but also advances our understanding of the complex relationship between P. aeruginosa and filamentous Pf phages.
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Affiliation(s)
- Amelia K. Schmidt
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | | | - Julie D. Pourtois
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Elizabeth Burgener
- Department of Pediatrics, Division of Pulmonology, Children’s Hospital of Los Angeles, University of Southern California, Los Angeles, CA, USA
| | - Dominick R. Faith
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Alex Joyce
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Tyrza Lamma
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
| | - Geetha Kumar
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kerala, India
| | - Paul L. Bollyky
- Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Patrick R. Secor
- Division of Biological Sciences, University of Montana, Missoula, Montana, USA
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12
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Madhu B, Lakdawala MF, Gumienny TL. The DBL-1/TGF-β signaling pathway tailors behavioral and molecular host responses to a variety of bacteria in Caenorhabditis elegans. eLife 2023; 12:e75831. [PMID: 37750680 PMCID: PMC10567113 DOI: 10.7554/elife.75831] [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: 12/07/2021] [Accepted: 09/25/2023] [Indexed: 09/27/2023] Open
Abstract
Generating specific, robust protective responses to different bacteria is vital for animal survival. Here, we address the role of transforming growth factor β (TGF-β) member DBL-1 in regulating signature host defense responses in Caenorhabditis elegans to human opportunistic Gram-negative and Gram-positive pathogens. Canonical DBL-1 signaling is required to suppress avoidance behavior in response to Gram-negative, but not Gram-positive bacteria. We propose that in the absence of DBL-1, animals perceive some bacteria as more harmful. Animals activate DBL-1 pathway activity in response to Gram-negative bacteria and strongly repress it in response to select Gram-positive bacteria, demonstrating bacteria-responsive regulation of DBL-1 signaling. DBL-1 signaling differentially regulates expression of target innate immunity genes depending on the bacterial exposure. These findings highlight a central role for TGF-β in tailoring a suite of bacteria-specific host defenses.
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Affiliation(s)
- Bhoomi Madhu
- Department of Biology, Texas Woman’s UniversityDentonUnited States
- Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Mohammed Farhan Lakdawala
- Department of Biology, Texas Woman’s UniversityDentonUnited States
- AbbVie (United States)WorcesterUnited States
| | - Tina L Gumienny
- Department of Biology, Texas Woman’s UniversityDentonUnited States
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13
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Peterson ND, Tse SY, Huang QJ, Wani KA, Schiffer CA, Pukkila-Worley R. Non-canonical pattern recognition of a pathogen-derived metabolite by a nuclear hormone receptor identifies virulent bacteria in C. elegans. Immunity 2023; 56:768-782.e9. [PMID: 36804958 PMCID: PMC10101930 DOI: 10.1016/j.immuni.2023.01.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/27/2022] [Accepted: 01/25/2023] [Indexed: 02/19/2023]
Abstract
Distinguishing infectious pathogens from harmless microorganisms is essential for animal health. The mechanisms used to identify infectious microbes are not fully understood, particularly in metazoan hosts that eat bacteria as their food source. Here, we characterized a non-canonical pattern-recognition system in Caenorhabditis elegans (C. elegans) that assesses the relative threat of virulent Pseudomonas aeruginosa (P. aeruginosa) to activate innate immunity. We discovered that the innate immune response in C. elegans was triggered by phenazine-1-carboxamide (PCN), a toxic metabolite produced by pathogenic strains of P. aeruginosa. We identified the nuclear hormone receptor NHR-86/HNF4 as the PCN sensor in C. elegans and validated that PCN bound to the ligand-binding domain of NHR-86/HNF4. Activation of NHR-86/HNF4 by PCN directly engaged a transcriptional program in intestinal epithelial cells that protected against P. aeruginosa. Thus, a bacterial metabolite is a pattern of pathogenesis surveilled by nematodes to identify a pathogen in its bacterial diet.
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Affiliation(s)
- Nicholas D Peterson
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Samantha Y Tse
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Qiuyu Judy Huang
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Khursheed A Wani
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Read Pukkila-Worley
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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Filipowicz A, Lalsiamthara J, Aballay A. Dissection of a sensorimotor circuit underlying pathogen aversion in C. elegans. BMC Biol 2022; 20:229. [PMID: 36209082 PMCID: PMC9548130 DOI: 10.1186/s12915-022-01424-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/28/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Altering animal behavior to reduce pathogen exposure is a key line of defense against pathogen attack. In Caenorhabditis elegans, alterations in intestinal physiology caused by pathogen colonization and sensation of microbial metabolites may lead to activation of pathogen aversive behaviors ranging from aversive reflexes to learned avoidance. However, the neural circuitry between chemosensory neurons that sense pathogenic bacterial cues and the motor neurons responsible for avoidance-associated locomotion remains unknown. RESULTS Using C. elegans, we found that backward locomotion was a component of learned pathogen avoidance, as animals pre-exposed to Pseudomonas aeruginosa or Enterococcus faecalis showed reflexive aversion to drops of the bacteria driven by chemosensory neurons, including the olfactory AWB neurons. This response also involved intestinal distention and, for E. faecalis, required expression of TRPM channels in the intestine and excretory system. Additionally, we uncovered a circuit composed of olfactory neurons, interneurons, and motor neurons that controls the backward locomotion crucial for learned reflexive aversion to pathogenic bacteria, learned avoidance, and the repulsive odor 2-nonanone. CONCLUSIONS Using whole-brain simulation and functional assays, we uncovered a novel sensorimotor circuit governing learned reflexive aversion. The discovery of a complete sensorimotor circuit for reflexive aversion demonstrates the utility of using the C. elegans connectome and computational modeling in uncovering new neuronal regulators of behavior.
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Affiliation(s)
- Adam Filipowicz
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR, 97239, USA
- Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Jonathan Lalsiamthara
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Alejandro Aballay
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR, 97239, USA.
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Positive interaction between ASH and ASK sensory neurons accelerates nociception and inhibits behavioral adaptation. iScience 2022; 25:105287. [PMID: 36304123 PMCID: PMC9593764 DOI: 10.1016/j.isci.2022.105287] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 05/22/2022] [Accepted: 10/04/2022] [Indexed: 11/23/2022] Open
Abstract
Central and peripheral sensory neurons tightly regulate nociception and avoidance behavior. The peripheral modulation of nociception provides more veridical and instantaneous information for animals to achieve rapid, more fine-tuned and concentrated behavioral responses. In this study, we find that positive interaction between ASH and ASK sensory neurons is essential for the fast-rising phase of ASH Ca2+ responses to noxious copper ions and inhibits the adaption of avoiding Cu2+. We reveal the underlying neuronal circuit mechanism. ASK accelerates the ASH Ca2+ responses by transferring cGMP through gap junctions. ASH excites ASK via a disinhibitory neuronal circuit composed of ASH, AIA, and ASK. Avoidance adaptation depends on the slope rate of the rising phase of ASH Ca2+ responses. Thus, in addition to amplitude, sensory kinetics is significant for sensations and behaviors, especially for sensory and behavioral adaptations.
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Lalsiamthara J, Aballay A. The gut efflux pump MRP-1 exports oxidized glutathione as a danger signal that stimulates behavioral immunity and aversive learning. Commun Biol 2022; 5:422. [PMID: 35513700 PMCID: PMC9072357 DOI: 10.1038/s42003-022-03381-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 04/19/2022] [Indexed: 11/09/2022] Open
Abstract
Innate immune surveillance, which monitors the presence of potentially harmful microorganisms and the perturbations of host physiology that occur in response to infections, is critical to distinguish pathogens from beneficial microbes. Here, we show that multidrug resistance-associated protein-1 (MRP-1) functions in the basolateral membrane of intestinal cells to transport byproducts of cellular redox reactions to control both molecular and behavioral immunity in Caenorhabditis elegans. Pseudomonas aeruginosa infection disrupts glutathione homeostasis, leading to the excess production of the MRP-1 substrate, oxidized glutathione (GSSG). Extracellular GSSG triggers pathogen avoidance behavior and primes naïve C. elegans to induce aversive learning behavior via neural NMDA class glutamate receptor-1 (NMR-1). Our results indicate that MRP-1 transports GSSG, which acts as a danger signal capable of warning C. elegans of changes in intestinal homeostasis, thereby initiating a gut neural signal that elicits an appropriate host defense response. The multidrug resistance-associated protein-1 (MRP-1) functions in the basolateral membrane of intestinal cells to transport byproducts of cellular redox reactions to control both molecular and behavioral immunity in C. elegans.
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Affiliation(s)
- Jonathan Lalsiamthara
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University Portland, Oregon, OR, 97239, USA
| | - Alejandro Aballay
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University Portland, Oregon, OR, 97239, USA.
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Petersen C, Pees B, Martínez Christophersen C, Leippe M. Preconditioning With Natural Microbiota Strain Ochrobactrum vermis MYb71 Influences Caenorhabditis elegans Behavior. Front Cell Infect Microbiol 2021; 11:775634. [PMID: 34976859 PMCID: PMC8718863 DOI: 10.3389/fcimb.2021.775634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
In comparison with the standard monoxenic maintenance in the laboratory, rearing the nematode Caenorhabditis elegans on its natural microbiota improves its fitness and immunity against pathogens. Although C. elegans is known to exhibit choice behavior and pathogen avoidance behavior, little is known about whether C. elegans actively chooses its (beneficial) microbiota and whether the microbiota influences worm behavior. We examined eleven natural C. elegans isolates in a multiple-choice experiment for their choice behavior toward four natural microbiota bacteria and found that microbiota choice varied among C. elegans isolates. The natural C. elegans isolate MY2079 changed its choice behavior toward microbiota isolate Ochrobactrum vermis MYb71 in both multiple-choice and binary-choice experiments, in particular on proliferating bacteria: O. vermis MYb71 was chosen less than other microbiota bacteria or OP50, but only after preconditioning with MYb71. Examining escape behavior and worm fitness on MYb71, we ruled out pathogenicity of MYb71 and consequently learned pathogen avoidance behavior as the main driver of the behavioral change toward MYb71. The change in behavior of C. elegans MY2079 toward microbiota bacterium MYb71 demonstrates how the microbiota influences the worm's choice. These results might give a baseline for future research on host-microbiota interaction in the C. elegans model.
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Affiliation(s)
- Carola Petersen
- Department of Comparative Immunobiology, Zoological Institute, Christian-Albrechts University, Kiel, Germany
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Ronan EA, Xiao R, Shawn Xu XZ. TRP channels: Intestinal bloating TRiPs up pathogen avoidance. Cell Calcium 2021; 98:102446. [PMID: 34303264 DOI: 10.1016/j.ceca.2021.102446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 07/05/2021] [Indexed: 11/15/2022]
Abstract
Transient receptor potential (TRP) channels are expressed in many nonneural tissues where their functions are not well known. Using C. elegans as a model, a new study demonstrated that colonization of the Gram-positive pathogenic bacteria E. faecalis in the intestine causes intestinal distention. Two TRPM channels sense such intestinal distension to trigger fast pathogen avoidance behavior, thereby limiting pathogen infection. This work signifies the novel role of TRP channels in gut physiology and pathogen defense.
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Affiliation(s)
- Elizabeth A Ronan
- Life Sciences Institute, University of Michigan, Ann Arbor 48109, United States; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor 48109, United States
| | - Rui Xiao
- Department of Aging and Geriatric Research, Institute on Aging, College of Medicine, University of Florida, Gainesville, FL 32610, United States.
| | - X Z Shawn Xu
- Life Sciences Institute, University of Michigan, Ann Arbor 48109, United States; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor 48109, United States.
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