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Yang H, Verhoeve VI, Chandler CE, Nallar S, Snyder GA, Ernst RK, Gillespie JJ. Structural determination of Rickettsia lipid A without chemical extraction confirms shorter acyl chains in later-evolving spotted fever group pathogens. mSphere 2024; 9:e0060923. [PMID: 38259062 PMCID: PMC10900879 DOI: 10.1128/msphere.00609-23] [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: 11/20/2023] [Accepted: 12/12/2023] [Indexed: 01/24/2024] Open
Abstract
Rickettsiae are Gram-negative obligate intracellular parasites of numerous eukaryotes. Human pathogens of the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae infect blood-feeding arthropods, have dissimilar clinical manifestations, and possess unique genomic and morphological attributes. Lacking glycolysis, rickettsiae pilfer numerous metabolites from the host cytosol to synthesize peptidoglycan and lipopolysaccharide (LPS). For LPS, O-antigen immunogenicity varies between SFG and TG pathogens; however, lipid A proinflammatory potential is unknown. We previously demonstrated that Rickettsia akari (TRG), Rickettsia typhi (TG), and Rickettsia montanensis (SFG) produce lipid A with long 2' secondary acyl chains (C16 or C18) compared to short 2' secondary acyl chains (C12) in Rickettsia rickettsii (SFG) lipid A. To further probe this structural heterogeneity and estimate a time point when shorter 2' secondary acyl chains originated, we generated lipid A structures for two additional SFG rickettsiae (Rickettsia rhipicephali and Rickettsia parkeri) utilizing fast lipid analysis technique adopted for use with tandem mass spectrometry (FLATn). FLATn allowed analysis of lipid A structure directly from host cell-purified bacteria, providing a substantial improvement over lipid A chemical extraction. FLATn-derived structures indicate SFG rickettsiae diverging after R. rhipicephali evolved shorter 2' secondary acyl chains. While 2' secondary acyl chain lengths do not distinguish Rickettsia pathogens from non-pathogens, in silico analyses of Rickettsia LpxL late acyltransferases revealed discrete active sites and hydrocarbon rulers for long versus short 2' secondary acyl chain addition. Our collective data warrant determining Rickettsia lipid A inflammatory potential and how structural heterogeneity impacts lipid A-host receptor interactions.IMPORTANCEDeforestation, urbanization, and homelessness lead to spikes in Rickettsioses. Vector-borne human pathogens of transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae differ by clinical manifestations, immunopathology, genome composition, and morphology. We previously showed that lipid A (or endotoxin), the membrane anchor of Gram-negative bacterial lipopolysaccharide (LPS), structurally differs in Rickettsia rickettsii (later-evolving SFG) relative to Rickettsia montanensis (basal SFG), Rickettsia typhi (TG), and Rickettsia akari (TRG). As lipid A structure influences recognition potential in vertebrate LPS sensors, further assessment of Rickettsia lipid A structural heterogeneity is needed. Here, we sidestepped the difficulty of ex vivo lipid A chemical extraction by utilizing fast lipid analysis technique adopted for use with tandem mass spectrometry, a new procedure for generating lipid A structures directly from host cell-purified bacteria. These data confirm that later-evolving SFG pathogens synthesize structurally distinct lipid A. Our findings impact interpreting immune responses to different Rickettsia pathogens and utilizing lipid A adjuvant or anti-inflammatory properties in vaccinology.
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Affiliation(s)
- Hyojik Yang
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Victoria I. Verhoeve
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
| | - Courtney E. Chandler
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Shreeram Nallar
- Division of Vaccine Research, Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA
| | - Greg A. Snyder
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
- Division of Vaccine Research, Institute of Human Virology, University of Maryland, Baltimore, Maryland, USA
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, Maryland, USA
| | - Joseph J. Gillespie
- Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, Maryland, USA
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2
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Dahmani M, Zhu JC, Cook JH, Riley SP. Anaphylatoxin signaling activates macrophages to control intracellular Rickettsia proliferation. Microbiol Spectr 2023; 11:e0253823. [PMID: 37855623 PMCID: PMC10714731 DOI: 10.1128/spectrum.02538-23] [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: 06/20/2023] [Accepted: 09/11/2023] [Indexed: 10/20/2023] Open
Abstract
IMPORTANCE Pathogenic Rickettsia species are extremely dangerous bacteria that grow within the cytoplasm of host mammalian cells. In most cases, these bacteria are able to overpower the host cell and grow within the protected environment of the cytoplasm. However, a dramatic conflict occurs when Rickettsia encounter innate immune cells; the bacteria can "win" by taking over the host, or the bacteria can "lose" if the host cell efficiently fights the infection. This manuscript examines how the immune complement system is able to detect the presence of Rickettsia and alert nearby cells. Byproducts of complement activation called anaphylatoxins are signals that "activate" innate immune cells to mount an aggressive defensive strategy. This study enhances our collective understanding of the innate immune reaction to intracellular bacteria and will contribute to future efforts at controlling these dangerous infections.
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Affiliation(s)
- Mustapha Dahmani
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Jinyi C. Zhu
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Jack H. Cook
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
| | - Sean P. Riley
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA
- Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
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3
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Yang H, Verhoeve VI, Chandler CE, Nallar S, Snyder GA, Ernst RK, Gillespie JJ. Structural determination of Rickettsia lipid A without chemical extraction confirms shorter acyl chains in later-evolving Spotted Fever Group pathogens. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.06.547954. [PMID: 37461656 PMCID: PMC10350050 DOI: 10.1101/2023.07.06.547954] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Rickettsiae are Gram-negative obligate intracellular parasites of numerous eukaryotes. Human pathogens of the Transitional Group (TRG), Typhus Group (TG), and Spotted Fever Group (SFG) rickettsiae infect blood-feeding arthropods, have dissimilar clinical manifestations, and possess unique genomic and morphological attributes. Lacking glycolysis, rickettsiae pilfer numerous metabolites from host cytosol to synthesize peptidoglycan and lipopolysaccharide (LPS). For LPS, O-antigen immunogenicity varies between SFG and TG pathogens; however, lipid A proinflammatory potential is unknown. We previously demonstrated that R. akari (TRG), R. typhi (TG), and R. montanensis (SFG) produce lipid A with long 2' secondary acyl chains (C16 or C18) compared to short 2' secondary acyl chains (C12) in R. rickettsii (SFG) lipid A. To further probe this structural heterogeneity and estimate a time point when shorter 2' secondary acyl chains originated, we generated lipid A structures for two additional SFG rickettsiae ( R. rhipicephali and R. parkeri ) utilizing Fast Lipid Analysis Technique adopted for use with tandem mass spectrometry (FLAT n ). FLAT n allowed analysis of lipid A structure directly from host cell-purified bacteria, providing substantial improvement over lipid A chemical extraction. FLAT n -derived structures indicate SFG rickettsiae diverging after R. rhipicephali evolved shorter 2' secondary acyl chains. Bioinformatics analysis of Rickettsia LpxL late acyltransferases revealed discrete active sites and hydrocarbon rulers for long versus short 2' secondary acyl chain addition. While the significance of different lipid A structures for diverse Rickettsia pathogens is unknown, our success using FLAT n will facilitate determining how structural heterogeneity impacts interactions with host lipid A receptors and overall inflammatory potential. IMPORTANCE Deforestation, urbanization, and homelessness lead to spikes in Rickettsioses. Vector-borne human pathogens of Transitional Group (TRG), Typhus Group (TG), and Spotted Fever Group (SFG) rickettsiae differ by clinical manifestations, immunopathology, genome composition, and morphology. We previously showed that lipid A (or endotoxin), the membrane anchor of Gram-negative bacterial lipopolysaccharide (LPS), structurally differs in R. rickettsii (later-evolving SFG) relative to R. montanensis (basal SFG), R. typhi (TG), and R. akari (TRG). As lipid A structure influences recognition potential in vertebrate LPS sensors, further assessment of Rickettsia lipid A structural heterogeneity is needed. Here, we sidestepped the difficulty of ex vivo lipid A chemical extraction by utilizing FLAT n , a new procedure for generating lipid A structures directly from host cell-purified bacteria. These data confirm later-evolving SFG pathogens synthesize structurally distinct lipid A. Our findings impact interpreting immune responses to different Rickettsia pathogens and utilizing lipid A adjuvant or anti-inflammatory properties in vaccinology.
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4
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Londoño AF, Scorpio DG, Dumler JS. Innate immunity in rickettsial infections. Front Cell Infect Microbiol 2023; 13:1187267. [PMID: 37228668 PMCID: PMC10203653 DOI: 10.3389/fcimb.2023.1187267] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 04/19/2023] [Indexed: 05/27/2023] Open
Abstract
Rickettsial agents are a diverse group of alpha-proteobacteria within the order Rickettsiales, which possesses two families with human pathogens, Rickettsiaceae and Anaplasmataceae. These obligate intracellular bacteria are most frequently transmitted by arthropod vectors, a first step in the pathogens' avoidance of host cell defenses. Considerable study of the immune responses to infection and those that result in protective immunity have been conducted. Less study has focused on the initial events and mechanism by which these bacteria avoid the innate immune responses of the hosts to survive within and propagate from host cells. By evaluating the major mechanisms of evading innate immunity, a range of similarities among these bacteria become apparent, including mechanisms to escape initial destruction in phagolysosomes of professional phagocytes, those that dampen the responses of innate immune cells or subvert signaling and recognition pathways related to apoptosis, autophagy, proinflammatory responses, and mechanisms by which these microbes attach to and enter cells or those molecules that trigger the host responses. To illustrate these principles, this review will focus on two common rickettsial agents that occur globally, Rickettsia species and Anaplasma phagocytophilum.
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Affiliation(s)
- Andrés F. Londoño
- The Henry M. Jackson Foundation for Advancement in Military Medicine, Bethesda, MD, United States
- Department of Pathology, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Diana G. Scorpio
- Host-Pathogen Interactions Program, Texas Biomedical Research Institute, San Antonio, TX, United States
| | - J. Stephen Dumler
- Department of Pathology, School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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5
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Cente M, Danchenko M, Skultety L, Filipcik P, Sekeyova Z. Rickettsia Deregulates Genes Coding for the Neurotoxic Cell Response Pathways in Cerebrocortical Neurons In Vitro. Cells 2023; 12:cells12091235. [PMID: 37174635 PMCID: PMC10177168 DOI: 10.3390/cells12091235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Rickettsial infections of the central nervous system (CNS) are manifested by severe neurological symptoms and represent a serious life-threatening condition. Despite the considerable health danger, only a few studies have been conducted focusing on the pathogenesis induced by Rickettsia sp. in CNS. To investigate the signaling pathways associated with the neurotoxic effects of rickettsiae, we employed an experimental model of cerebrocortical neurons combined with molecular profiling and comprehensive bioinformatic analysis. The cytopathic effect induced by Rickettsia akari and Rickettsia slovaca was demonstrated by decreased neuronal viability, structural changes in cell morphology, and extensive fragmentation of neurites in vitro. Targeted profiling revealed the deregulation of genes involved in the neuroinflammatory and neurotoxic cell response pathways. Although quantitative analysis showed differences in gene expression response, functional annotation revealed that the biological processes are largely shared between both Rickettsia species. The identified enriched pathways are associated with cytokine signaling, chemotaxis of immune cells, responses to infectious agents, interactions between neurons, endothelial and glial cells, and regulation of neuronal apoptotic processes. The findings of our study provide new insight into the etiopathogenesis of CNS infection and further expand the understanding of molecular signaling associated with neuroinvasive Rickettsia species.
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Affiliation(s)
- Martin Cente
- Institute of Neuroimmunology, Slovak Academy of Sciences, Dubravska cesta 9, 845 10 Bratislava, Slovakia
| | - Monika Danchenko
- Department of Rickettsiology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Ludovit Skultety
- Department of Rickettsiology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
| | - Peter Filipcik
- Institute of Neuroimmunology, Slovak Academy of Sciences, Dubravska cesta 9, 845 10 Bratislava, Slovakia
| | - Zuzana Sekeyova
- Department of Rickettsiology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia
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IL-1 Superfamily Member ( IL-1A, IL-1B and IL-18) Genetic Variants Influence Susceptibility and Clinical Course of Mediterranean Spotter Fever. Biomolecules 2022; 12:biom12121892. [PMID: 36551320 PMCID: PMC9816934 DOI: 10.3390/biom12121892] [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: 10/14/2022] [Revised: 12/01/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022] Open
Abstract
Mediterranean Spotted Fever (MSF) is one of the most common spotted fever Rickettsioses. Most cases of MSF follow a benign course, with a minority of cases being fatal. The severity of the infection depends on bacterial virulence, dose and host factors such as effective immune response and genetic background. Herein, we reported data on typing by competitive allele-specific PCR of functionally relevant polymorphisms of genes coding for MyD88 adapter-like (Mal/TIRAP) protein (rs8177374), interleukin(IL)-1 cluster (IL-1A rs1800587, IL-1B rs16944 and rs1143634) and IL-18 (rs187238), which might be crucial for an efficient immune response. The results enlighten the role that IL-1 gene cluster variants might play in susceptibility against Rickettsia conorii infection. In particular, the IL-1A rs1800587TT genotype was significantly increased in patients alone and combined in a haplotype composed by minor alleles rs1800587T, rs16944A and rs1143634A. This result was confirmed using the decision tree heuristic approach. Using this methodology, IL-1A rs1800587TT genotype was the better discrimination key among MSF patients and controls. In addition, the IL-1 gene cluster SNP genotypes containing minor alleles and IL-18 rs187238G positive genotypes were found as associated with risk of severe complications such as sepsis, septic shock, acute respiratory distress syndrome and coma. In conclusion, these data suggest that the evaluation of IL-1A, IL-1B and IL-18 gene SNPs can add useful information on the clinical course of patients affected by Mediterranean Spotted Fever, even if further confirmatory studies will be necessary.
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A Vaccine for Canine Rocky Mountain Spotted Fever: An Unmet One Health Need. Vaccines (Basel) 2022; 10:vaccines10101626. [PMID: 36298491 PMCID: PMC9610744 DOI: 10.3390/vaccines10101626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 09/22/2022] [Accepted: 09/25/2022] [Indexed: 11/17/2022] Open
Abstract
Outbreaks of life-threatening Rocky Mountain spotted fever in humans and dogs associated with a canine-tick maintenance cycle constitute an important One Health opportunity. The reality of the problem has been observed strikingly in Mexico, Brazil, Colombia, and Native American tribal lands in Arizona. The brown dog tick, Rhipicephalus sanguineus sensu lato, acquires the rickettsia from bacteremic dogs and can maintain the bacterium transtadially to the next tick stage. The subsequent adult tick can then transmit infection to a new host, as shown by guinea pig models. These brown dog ticks maintain spotted fever group rickettsiae transovarially through many generations, thus serving as both vector and reservoir. Vaccine containing whole-killed R. rickettsii does not stimulate sufficient immunity. Studies of Rickettsia subunit antigens have demonstrated that conformationally preserved outer-membrane autotransporter proteins A and B are the leading vaccine candidates. The possibility of a potentially safe and effective live attenuated vaccine has only begun to be explored as gene knockout methods are applied to these obligately intracellular pathogens.
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8
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Dahmani M, Cook JH, Zhu JC, Riley SP. Contribution of classical complement activation and IgM to the control of Rickettsia infection. Mol Microbiol 2021; 116:1476-1488. [PMID: 34725868 PMCID: PMC8955150 DOI: 10.1111/mmi.14839] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 01/02/2023]
Abstract
Pathogenic Rickettsia are obligate intracellular bacteria and the etiologic agents of many life‐threatening infectious diseases. Due to the serious nature of these infections, it is imperative to both identify the responsive immune sensory pathways and understand the associated immune mechanisms that restrict Rickettsia proliferation. Previous studies have demonstrated that the mammalian complement system is both activated during Rickettsia infection and contributes to the immune response to infection. To further define this component of the mammalian anti‐Rickettsia immune response, we sought to identify the mechanism(s) of complement activation during Rickettsia infection. We have employed a series of in vitro and in vivo models of infection to investigate the role of the classical complement activation pathway during Rickettsia infection. Depletion or elimination of complement activity demonstrates that both C1q and pre‐existing IgM contribute to complement activation; thus implicating the classical complement system in Rickettsia‐mediated complement activation. Elimination of the classical complement pathway from mice increases susceptibility to R. australis infection with both increased bacterial loads in multiple tissues and decreased immune activation markers. This study highlights the role of the classical complement pathway in immunity against Rickettsia and implicates resident Rickettsia‐responsive IgM in the response to infection.
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Affiliation(s)
- Mustapha Dahmani
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA.,Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
| | - Jack H Cook
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA.,Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
| | - Jinyi C Zhu
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA.,Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
| | - Sean P Riley
- Department of Veterinary Medicine, University of Maryland-College Park, College Park, Maryland, USA.,Virginia-Maryland College of Veterinary Medicine, College Park, Maryland, USA
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9
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Abstract
Spikes in rickettsioses occur as deforestation, urbanization, and homelessness increase human exposure to blood-feeding arthropods. Still, effective Rickettsia vaccines remain elusive. Species of Rickettsia (Alphaproteobacteria: Rickettsiales) are obligate intracellular parasites of a wide range of eukaryotes, with recognized arthropod-borne human pathogens belonging to the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae. Growing in the host cytosol, rickettsiae pilfer numerous metabolites to make a typical Gram-negative bacterial cell envelope. The O-antigen of rickettsial lipopolysaccharide (LPS) is immunogenic and has been shown to tether the S-layer to the rickettsial surface; however, little is known about the structure and immunogenicity of the Rickettsia lipid A moiety. The structure of lipid A, the membrane anchor of LPS, affects the ability of this molecule to interact with components of the host innate immune system, specifically the MD-2/TLR4 receptor complex. To dissect the host responses that can occur during Rickettsia in vitro and in vivo infection, structural analysis of Rickettsia lipid A is needed. Lipid A was extracted from four Rickettsia species and structurally analyzed. R. akari (TRG), R. typhi (TG), and R. montanensis (SFG) produced a similar structure, whereas R. rickettsii (SFG) altered the length of a secondary acyl group. While all structures have longer acyl chains than known highly inflammatory hexa-acylated lipid A structures, the R. rickettsii modification should differentially alter interactions with the hydrophobic internal pocket in MD2. The significance of these characteristics toward inflammatory potential as well as membrane dynamics between arthropod and vertebrate cellular environments warrants further investigation. Our work adds lipid A to the secretome and O-antigen as variable factors possibly correlating with phenotypically diverse rickettsioses. IMPORTANCE Spikes in rickettsioses occur as deforestation, urbanization, and homelessness increase human exposure to blood-feeding arthropods. Still, effective Rickettsia vaccines remain elusive. Recent studies have determined that Rickettsia lipopolysaccharide anchors the protective S-layer to the bacterial surface and elicits bactericidal antibodies. Furthermore, growing immunological evidence suggests vertebrate sensors (MD-2/TLR4 and noncanonical inflammasome) typically triggered by the lipid A portion of lipopolysaccharide are activated during Rickettsia infection. However, the immunopotency of Rickettsia lipid A is unknown due to poor appreciation for its structure. We determined lipid A structures for four distinct rickettsiae, revealing longer acyl chains relative to highly inflammatory bacterial lipid A. Surprisingly, lipid A of the Rocky Mountain spotted fever agent deviates in structure from other rickettsiae. Thus, lipid A divergence may contribute to variable disease phenotypes, sounding an alarm for determining its immunopotency and possible utility (i.e., as an adjuvant or anti-inflammatory) for development of more prudent rickettsiacidal therapies.
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10
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Bechelli J, Rumfield CS, Walker DH, Widen S, Khanipov K, Fang R. Subversion of Host Innate Immunity by Rickettsia australis via a Modified Autophagic Response in Macrophages. Front Immunol 2021; 12:638469. [PMID: 33912163 PMCID: PMC8071864 DOI: 10.3389/fimmu.2021.638469] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 03/11/2021] [Indexed: 11/13/2022] Open
Abstract
We recently reported that the in vitro and in vivo survivals of Rickettsia australis are Atg5-dependent, in association with an inhibited level of anti-rickettsial cytokine, IL-1β. In the present study, we sought to investigate how R. australis interacts with host innate immunity via an Atg5-dependent autophagic response. We found that the serum levels of IFN-γ and G-CSF in R. australis-infected Atg5flox/floxLyz-Cre mice were significantly less compared to Atg5flox/flox mice, accompanied by significantly lower rickettsial loads in tissues with inflammatory cellular infiltrations including neutrophils. R. australis infection differentially regulated a significant number of genes in bone marrow-derived macrophages (BMMs) in an Atg5-depdent fashion as determined by RNA sequencing and Ingenuity Pathway Analysis, including genes in the molecular networks of IL-1 family cytokines and PI3K-Akt-mTOR. The secretion levels of inflammatory cytokines, such as IL-1α, IL-18, TNF-α, and IL-6, by R. australis-infected Atg5flox/floxLyz-Cre BMMs were significantly greater compared to infected Atg5flox/flox BMMs. Interestingly, R. australis significantly increased the levels of phosphorylated mTOR and P70S6K at a time when the autophagic response is induced. Rapamycin treatment nearly abolished the phosphorylated mTOR and P70S6K but did not promote significant autophagic flux during R. australis infection. These results highlight that R. australis modulates an Atg5-dependent autophagic response, which is not sensitive to regulation by mTORC1 signaling in macrophages. Overall, we demonstrate that R. australis counteracts host innate immunity including IL-1β-dependent inflammatory response to support the bacterial survival via an mTORC1-resistant autophagic response in macrophages.
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Affiliation(s)
- Jeremy Bechelli
- Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, United States.,Department of Biological Sciences, Sam Houston State University, Huntsville, TX, United States
| | - Claire S Rumfield
- Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, United States.,Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States
| | - David H Walker
- Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, United States.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
| | - Steven Widen
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, TX, United States
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, University of Texas Medical Branch at Galveston, Galveston, TX, United States
| | - Rong Fang
- Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, United States.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
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11
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Kalinina O, Talley S, Zamora-Pineda J, Paik W, Campbell EM, Knight KL. Amelioration of Graft-versus-Host Disease by Exopolysaccharide from a Commensal Bacterium. THE JOURNAL OF IMMUNOLOGY 2021; 206:2101-2108. [PMID: 33846225 DOI: 10.4049/jimmunol.2000780] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 03/02/2021] [Indexed: 01/07/2023]
Abstract
Acute graft-versus-host disease (aGvHD) is a severe, often lethal, complication of hematopoietic stem cell transplantation, and although prophylactic regimens are given as standard pretransplantation therapy, up to 60% of these patients develop aGvHD, and require additional immunosuppressive intervention. We treated mice with a purified probiotic molecule, exopolysaccharide (EPS) from Bacillus subtilis, shortly before and after induction of aGvHD and found that, whereas only 10% of control mice survived to day 80, 70% of EPS-treated mice survived to 80 d. EPS treatment of donor-only mice resulted in ∼60% survival. Using a biosensor mouse model to assess inflammation in live mice during aGvHD, we found that EPS prevented the activation of alloreactive donor T cells. In vitro, EPS did not affect T cells directly but, instead, induced bone marrow-derived dendritic cells (BMDCs) that displayed characteristics of inhibitory dendritic cells (DCs). Development of these BMDCs required TLR4 signaling through both MyD88 and TRIF pathways. Using BMDCs derived from IDO knockout mice, we showed that T cell inhibition by EPS-treated BMDCs was mediated through the suppressive effects of IDO. These studies describe a bacterial molecule that modulates immune responses by inducing inhibitory DCs in a TLR4-dependent manner, and these cells have the capacity to inhibit T cell activation through IDO. We suggest that EPS or EPS-treated DCs can serve as novel agents for preventing aGvHD.
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Affiliation(s)
- Olga Kalinina
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
| | - Sarah Talley
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
| | - Jesus Zamora-Pineda
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
| | - Wonbeom Paik
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
| | - Edward M Campbell
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
| | - Katherine L Knight
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL
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12
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Fisher JR, Chroust ZD, Onyoni F, Soong L. Pattern Recognition Receptors in Innate Immunity to Obligate Intracellular Bacteria. ZOONOSES (BURLINGTON, MASS.) 2021; 1:10. [PMID: 35282331 PMCID: PMC8909792 DOI: 10.15212/zoonoses-2021-0011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Host pattern recognition receptors (PRRs) are crucial for sensing pathogenic microorganisms, launching innate responses, and shaping pathogen-specific adaptive immunity during infection. Rickettsia spp., Orientia tsutsugamushi, Anaplasma spp., Ehrlichia spp., and Coxiella burnetii are obligate intracellular bacteria, which can only replicate within host cells and must evade immune detection to successfully propagate. These five bacterial species are zoonotic pathogens of clinical or agricultural importance, yet, uncovering how immune recognition occurs has remained challenging. Recent evidence from in-vitro studies and animal models has offered new insights into the types and kinetics of PRR activation during infection with Rickettsia spp., A. phagocytophilum, E. chaffeensis, and C. burnetii, respectively. However, much less is known in these regards for O. tsutsugamushi infection, until the recent discovery for the role of the C-type lectin receptor Mincle during lethal infection in mice and in primary macrophage cultures. This review gives a brief summary for clinical and epidemiologic features of these five bacterial infections, focuses on fundamental biologic facets of infection, and recent advances in host recognition. In addition, we discuss knowledge gaps for innate recognition of these bacteria in the context of disease pathogenesis.
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Affiliation(s)
- James R. Fisher
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- School of Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Zachary D. Chroust
- School of Medicine, University of Texas Medical Branch, Galveston, Texas, USA
| | - Florence Onyoni
- Graduate School of Biomedical Sciences, University of Texas Medical Branch, Galveston, Texas, USA
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, USA
- Corresponding author: Lynn Soong, Department of Microbiology and Immunology, University of Texas Medical Branch, 301 University Blvd. MRB 3.142, Galveston, Texas 77555-1070,
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Torina A, Villari S, Blanda V, Vullo S, La Manna MP, Shekarkar Azgomi M, Di Liberto D, de la Fuente J, Sireci G. Innate Immune Response to Tick-Borne Pathogens: Cellular and Molecular Mechanisms Induced in the Hosts. Int J Mol Sci 2020; 21:ijms21155437. [PMID: 32751625 PMCID: PMC7432002 DOI: 10.3390/ijms21155437] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022] Open
Abstract
Many pathogens are transmitted by tick bites, including Anaplasma spp., Ehrlichia spp., Rickettsia spp., Babesia and Theileria sensu stricto species. These pathogens cause infectious diseases both in animals and humans. Different types of immune effector mechanisms could be induced in hosts by these microorganisms, triggered either directly by pathogen-derived antigens or indirectly by molecules released by host cells binding to these antigens. The components of innate immunity, such as natural killer cells, complement proteins, macrophages, dendritic cells and tumor necrosis factor alpha, cause a rapid and intense protection for the acute phase of infectious diseases. Moreover, the onset of a pro-inflammatory state occurs upon the activation of the inflammasome, a protein scaffold with a key-role in host defense mechanism, regulating the action of caspase-1 and the maturation of interleukin-1β and IL-18 into bioactive molecules. During the infection caused by different microbial agents, very similar profiles of the human innate immune response are observed including secretion of IL-1α, IL-8, and IFN-α, and suppression of superoxide dismutase, IL-1Ra and IL-17A release. Innate immunity is activated immediately after the infection and inflammasome-mediated changes in the pro-inflammatory cytokines at systemic and intracellular levels can be detected as early as on days 2–5 after tick bite. The ongoing research field of “inflammasome biology” focuses on the interactions among molecules and cells of innate immune response that could be responsible for triggering a protective adaptive immunity. The knowledge of the innate immunity mechanisms, as well as the new targets of investigation arising by bioinformatics analysis, could lead to the development of new methods of emergency diagnosis and prevention of tick-borne infections.
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Affiliation(s)
- Alessandra Torina
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Sara Villari
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Valeria Blanda
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
- Correspondence:
| | - Stefano Vullo
- Istituto Zooprofilattico Sperimentale della Sicilia, Via Gino Marinuzzi 3, 90100 Palermo, Italy; (A.T.); (S.V.); (S.V.)
| | - Marco Pio La Manna
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - Mojtaba Shekarkar Azgomi
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - Diana Di Liberto
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
| | - José de la Fuente
- SaBio, Instituto de Investigación en Recursos Cinegéticos IREC-CSIC-UCLM-JCCM, Ronda de Toledo s/n, 13005 Ciudad Real, Spain;
- Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - Guido Sireci
- Central Laboratory of Advanced Diagnostic and Biological Research (CLADIBIOR), BIND, University Hospital “Paolo Giaccone”, Università degli studi di Palermo, Via del Vespro 129, 90100 Palermo, Italy; (M.P.L.M.); (M.S.A.); (D.D.L.); (G.S.)
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Activation of ASC Inflammasome Driven by Toll-Like Receptor 4 Contributes to Host Immunity against Rickettsial Infection. Infect Immun 2020; 88:IAI.00886-19. [PMID: 32014896 DOI: 10.1128/iai.00886-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 01/23/2020] [Indexed: 02/07/2023] Open
Abstract
Rickettsiae are cytosolically replicating, obligately intracellular bacteria causing human infections worldwide with potentially fatal outcomes. We previously showed that Rickettsia australis activates ASC inflammasome in macrophages. In the present study, host susceptibility of ASC inflammasome-deficient mice to R. australis was significantly greater than that of C57BL/6 (B6) controls and was accompanied by increased rickettsial loads in various organs. Impaired host control of R. australis in vivo in ASC-/- mice was associated with dramatically reduced levels of interleukin 1β (IL-1β), IL-18, and gamma interferon (IFN-γ) in sera. The intracellular concentrations of R. australis in bone marrow-derived macrophages (BMMs) of TLR4-/- and ASC-/- mice were significantly greater than those in BMMs of B6 controls, highlighting the important role of inflammasome and these molecules in controlling rickettsiae in macrophages. Compared to B6 BMMs, TLR4-/- BMMs failed to secrete a significant level of IL-1β and had reduced expression levels of pro-IL-1β in response to infection with R. australis, suggesting that rickettsiae activate ASC inflammasome via a Toll-like receptor 4 (TLR4)-dependent mechanism. Further mechanistic studies suggest that the lipopolysaccharide (LPS) purified from R. australis together with ATP stimulation led to cleavage of pro-caspase-1 and pro-IL-1β, resulting in TLR4-dependent secretion of IL-1β. Taken together, these observations indicate that activation of ASC inflammasome, most likely driven by interaction of TLR4 with rickettsial LPS, contributes to host protective immunity against R. australis These findings provide key insights into defining the interactions of rickettsiae with the host innate immune system.
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Quantitative Proteomics of the Endothelial Secretome Identifies RC0497 as Diagnostic of Acute Rickettsial Spotted Fever Infections. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:306-322. [PMID: 31955791 DOI: 10.1016/j.ajpath.2019.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 09/28/2019] [Accepted: 10/03/2019] [Indexed: 12/29/2022]
Abstract
Mediterranean spotted fever is a reemerging acute tick-borne infection produced by the α-proteobacterium, Rickettsia conorii. Rickettsia conorii infects vascular endothelial cells producing disseminated plasma leakage, manifesting as nonspecific fever, headache, and maculopapular rash. Because there are no available tests of early infection, Mediterranean spotted fever is often undiagnosed and untreated, resulting in significant mortality. To address this critical need, we have applied a quantitative proteomics pipeline for analyzing the secretome of primary human umbilical vein endothelial cells. Of the 104 proteins whose abundance changed significantly in the R. conorii-infected human umbilical vein endothelial cells' secretome, 46 proteins were up-regulated: 45 were host secreted proteins (including cytokines), and 1 was a rickettsial protein, the putative N-acetylmuramoyl-l-alanine amidase RC0497. Proteins with sequence highly homologous to RC0497 were found to be shared by many species of the spotted fever group rickettsiae, but not typhus group rickettsiae. Quantitative targeted proteomics studies of plasma from a mouse model of sublethal and lethal R. conorii identified RC0497 in the blood, and its circulating levels were proportionally associated with infection outcome. Finally, the presence of RC0497 in the serum samples from a cohort of humans presenting with acute rickettsioses was confirmed. The detection of RC0497 has the potential to be a sensitive and specific marker for acute rickettsial spotted rickettsioses.
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16
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Esteves E, Bizzarro B, Costa FB, Ramírez-Hernández A, Peti APF, Cataneo AHD, Wowk PF, Timóteo RP, Labruna MB, Silva Junior PI, Silva CL, Faccioli LH, Fogaça AC, Sorgi CA, Sá-Nunes A. Amblyomma sculptum Salivary PGE 2 Modulates the Dendritic Cell- Rickettsia rickettsii Interactions in vitro and in vivo. Front Immunol 2019; 10:118. [PMID: 30778355 PMCID: PMC6369204 DOI: 10.3389/fimmu.2019.00118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 01/15/2019] [Indexed: 01/06/2023] Open
Abstract
Amblyomma sculptum is an important vector of Rickettsia rickettsii, causative agent of Rocky Mountain spotted fever and the most lethal tick-borne pathogen affecting humans. To feed on the vertebrate host's blood, A. sculptum secretes a salivary mixture, which may interact with skin resident dendritic cells (DCs) and modulate their function. The present work was aimed at depicting the A. sculptum saliva-host DC network and the biochemical nature of the immunomodulatory component(s) involved in this interface. A. sculptum saliva inhibits the production of inflammatory cytokines by murine DCs stimulated with LPS. The fractionation of the low molecular weight salivary content by reversed-phase chromatography revealed active fractions eluting from 49 to 55% of the acetonitrile gradient. Previous studies suggested that this pattern of elution matches with that observed for prostaglandin E2 (PGE2) and the molecular identity of this lipid mediator was unambiguously confirmed by a new high-resolution mass spectrometry methodology. A productive infection of murine DCs by R. rickettsii was demonstrated for the first time leading to proinflammatory cytokine production that was inhibited by both A. sculptum saliva and PGE2, a result also achieved with human DCs. The adoptive transfer of murine DCs incubated with R. rickettsii followed by treatment with A. sculptum saliva or PGE2 did not change the cytokine profile associated to cellular recall responses while IgG2a-specific antibodies were decreased in the serum of these mice. Together, these findings emphasize the role of PGE2 as a universal immunomodulator of tick saliva. In addition, it contributes to new approaches to explore R. rickettsii-DC interactions both in vitro and in vivo.
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Affiliation(s)
- Eliane Esteves
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Bruna Bizzarro
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Francisco Borges Costa
- Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Alejandro Ramírez-Hernández
- Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Ana Paula Ferranti Peti
- Department of Clinical Analysis, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | | | - Pryscilla Fanini Wowk
- Laboratory of Molecular Virology, Carlos Chagas Institute, Fundação Oswaldo Cruz, Curitiba, Brazil
| | - Rodolfo Pessato Timóteo
- Institute of Natural and Biological Sciences, Federal University of Triângulo Mineiro, Uberaba, Brazil
| | - Marcelo Bahia Labruna
- Department of Preventive Veterinary Medicine and Animal Health, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | | | - Célio Lopes Silva
- Department of Biochemistry and Immunology, School of Medicine of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Lúcia Helena Faccioli
- Department of Clinical Analysis, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Andréa Cristina Fogaça
- Department de Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,National Institute of Science and Technology in Molecular Entomology, National Council of Scientific and Technological Development (INCT-EM/CNPq), Rio de Janeiro, Brazil
| | - Carlos Arterio Sorgi
- Department of Clinical Analysis, Toxicology and Food Science, School of Pharmaceutical Sciences of Ribeirao Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Anderson Sá-Nunes
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,National Institute of Science and Technology in Molecular Entomology, National Council of Scientific and Technological Development (INCT-EM/CNPq), Rio de Janeiro, Brazil
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17
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Atg5 Supports Rickettsia australis Infection in Macrophages In Vitro and In Vivo. Infect Immun 2018; 87:IAI.00651-18. [PMID: 30297526 PMCID: PMC6300621 DOI: 10.1128/iai.00651-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/28/2018] [Indexed: 01/26/2023] Open
Abstract
Rickettsiae can cause life-threatening infections in humans. Macrophages are one of the initial targets for rickettsiae after inoculation by ticks. However, it remains poorly understood how rickettsiae remain free in macrophages prior to establishing their infection in microvascular endothelial cells. Here, we demonstrated that the concentration of Rickettsia australis was significantly greater in infected tissues of Atg5flox/flox mice than in the counterparts of Atg5flox/flox Lyz-Cre mice, in association with a reduced level of interleukin-1β (IL-1β) in serum. The greater concentration of R. australis in Atg5flox/flox bone marrow-derived macrophages (BMMs) than in Atg5flox/flox Lyz-Cre BMMs in vitro was abolished by exogenous treatment with recombinant IL-1β. Rickettsia australis induced significantly increased levels of light chain 3 (LC3) form II (LC3-II) and LC3 puncta in Atg5-competent BMMs but not in Atg5-deficient BMMs, while no p62 turnover was observed. Further analysis found the colocalization of LC3 with a small portion of R. australis and Rickettsia-containing double-membrane-bound vacuoles in the BMMs of B6 mice. Moreover, treatment with rapamycin significantly increased the concentrations of R. australis in B6 BMMs compared to those in the untreated B6 BMM controls. Taken together, our results demonstrate that Atg5 favors R. australis infection in mouse macrophages in association with a suppressed level of IL-1β production but not active autophagy flux. These data highlight the contribution of Atg5 in macrophages to the pathogenesis of rickettsial diseases.
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Sahni A, Fang R, Sahni SK, Walker DH. Pathogenesis of Rickettsial Diseases: Pathogenic and Immune Mechanisms of an Endotheliotropic Infection. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2018; 14:127-152. [PMID: 30148688 DOI: 10.1146/annurev-pathmechdis-012418-012800] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Obligately intracytosolic rickettsiae that cycle between arthropod and vertebrate hosts cause human diseases with a spectrum of severity, primarily by targeting microvascular endothelial cells, resulting in endothelial dysfunction. Endothelial cells and mononuclear phagocytes have important roles in the intracellular killing of rickettsiae upon activation by the effector molecules of innate and adaptive immunity. In overwhelming infection, immunosuppressive effects contribute to the severity of illness. Rickettsia-host cell interactions involve host cell receptors for rickettsial ligands that mediate cell adhesion and, in some instances, trigger induced phagocytosis. Rickettsiae interact with host cell actin to effect both cellular entry and intracellular actin-based mobility. The interaction of rickettsiae with the host cell also involves rickettsial evasion of host defense mechanisms and exploitation of the intracellular environment. Signal transduction events exemplify these effects. An intriguing frontier is the array of rickettsial noncoding RNA molecules and their potential effects on the pathogenesis and transmission of rickettsial diseases.
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Affiliation(s)
- Abha Sahni
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - Rong Fang
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - Sanjeev K Sahni
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
| | - David H Walker
- The University of Texas Medical Branch at Galveston, Galveston, Texas 77555-0609, USA; , , ,
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Quiroz-Castañeda RE, Cobaxin-Cárdenas M, Cuervo-Soto LI. Exploring the diversity, infectivity and metabolomic landscape of Rickettsial infections for developing novel therapeutic intervention strategies. Cytokine 2018; 112:63-74. [PMID: 30072088 DOI: 10.1016/j.cyto.2018.07.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 07/09/2018] [Accepted: 07/17/2018] [Indexed: 12/25/2022]
Abstract
Rickettsioses are zoonotic infections caused by obligate intracellular bacteria of the genera Rickettsia that affect human health; sometimes humans being considered as accidental hosts. At a molecular level, the rickettsiae infection triggers molecular signaling leading to the secretion of proinflammatory cytokines. These cytokines direct the immune response to the host cell damage and pathogen removal. In this review, we present metabolic aspects of the host cell in the presence of rickettsiae and how this presence triggers an inflammatory response to cope with the pathogen. We also reviewed the secretion of cytokines that modulates host cell response at immune and metabolic levels.
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Affiliation(s)
- Rosa Estela Quiroz-Castañeda
- Unidad de Anaplasmosis, Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria, (CENID-PAVET, INIFAP), Carretera Federal Cuernavaca Cuautla 8534, Progreso, 62574 Jiutepec, Morelos, Mexico.
| | - Mayra Cobaxin-Cárdenas
- Unidad de Anaplasmosis, Centro Nacional de Investigación Disciplinaria en Parasitología Veterinaria, (CENID-PAVET, INIFAP), Carretera Federal Cuernavaca Cuautla 8534, Progreso, 62574 Jiutepec, Morelos, Mexico.
| | - Laura Inés Cuervo-Soto
- Facultad de Ciencias, Departamento de Biología, Universidad Antonio Nariño, Sede Circunvalar Carrera 3 Este, No. 47 A15, Bogotá, Colombia
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20
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Ge Y, Guo G, Ge B, Yin H, Yin H. The spleen microbiota of small wild mammals reveals distinct patterns with tick-borne bacteria. PLoS Negl Trop Dis 2018; 12:e0006499. [PMID: 29975692 PMCID: PMC6033388 DOI: 10.1371/journal.pntd.0006499] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/04/2018] [Indexed: 12/15/2022] Open
Abstract
Background Wild mammals serve as reservoirs for a variety of microbes and play an important role in the enzootic cycles of these microbes. Some of them are vector-borne bacteria in the genera Anaplasma, Ehrlichia and Rickettsia of the order Rickettsiales, which can cause febrile illnesses in human beings as well as animals. Anaplasma spp., Ehrlichia spp. and many spotted fever group (SFG) Rickettsia spp. are transmitted to mammalian hosts by tick vectors during blood meals. As a powerful sequencing method, the next generation sequencing can reveal the complexity of bacterial communities in humans and animals. Compared with limited studies on blood microbiota, however, much fewer studies have been carried out on spleen microbiota, which is very scarce in wild mammals. Chongming Island is the third biggest island in China. It was unclear whether there were any vector-borne bacteria in Chongming Island. In the present study, we explored the bacterial microbiota in the spleens of wild mice and shrews from the rural areas of Chongming Island and investigated the prevalence of vector-borne bacteria. Methodology/Principal findings Genomic DNAs were extracted from the spleen samples of 35 mice and shrews. The 16S rDNA V3-V4 regions of the DNA extracts were amplified by PCR and subjected to the 16S rDNA-targeted metagenomic sequencing on an Illumina MiSeq platform. All the 35 spleen samples obtained data with sufficient coverage (99.7–99.9%) for analysis. More than 1,300,000 sequences were obtained after quality control and classified into a total of 1,967 operational taxonomic units (OTUs) clustered at 97% similarity. The two most abundant bacterial phyla were Firmicutes and Proteobacteria according to the analysis of rarefied sequences. Among the bacterial communities detected in this study, Anaplasma, Rickettsia and Coxiella were adjacently clustered by hierarchical analysis. Significant differences in many bacterial features between Anaplasma-positive and Anaplasma-negative samples were identified by LEfSe analysis and Wilcoxon rank-sum test, suggesting that the Anaplasma-infection of small wild mammals was associated with a specific pattern of spleen microbiota. Conclusions/Significance Our study has comprehensively characterized the complex bacterial profiles in the spleens of wild mice and shrews from Chongming Island, Shanghai city. This work has revealed distinct spleen bacterial communities associated with tick-borne bacteria in wild animals. The detection of tick-borne bacteria highlights the risk of contracting pathogens with public health importance upon tick-exposure in the studied areas. In this study, the 16S rDNA-targeted metagenomic sequencing was used to determine the bacterial community and diversity in the spleens of small wild mammals from China. The 16S rDNAs were amplified from the spleen genomic DNAs of 35 small wild mice and shrews and sequenced by Illumina MiSeq technology. More than 1,300,000 sequences were obtained after quality control and classified into a total of 1,967 operational taxonomic units (OTUs) clustered at 97% similarity. The two most abundant bacterial phyla were Firmicutes and Proteobacteria according to the analysis of rarefied sequences. Within the bacterial communities detected in this study, vector-borne bacteria, Anaplasma, Rickettsia and Coxiella, were adjacently clustered by hierarchical analysis. Significant differences in many bacterial features between Anaplasma-positive and Anaplasma-negative samples were observed, suggesting that the infection of small wild mammals with Anaplasma is associated with a distinct pattern of spleen microbiota. This study has revealed the complex bacterial profiles in the spleens of wild mice and shrews. The detection of vector-borne bacteria highlights the role of wild mice and shrews as animal reservoirs with potential public health importance in the studied areas.
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Affiliation(s)
- Yan Ge
- Department of Immunology and Pathogen Biology, Tongji University School of Medicine, Shanghai, China
- * E-mail:
| | - Guangpu Guo
- Departement of Biotechnology, College of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Baoxue Ge
- Department of Immunology and Pathogen Biology, Tongji University School of Medicine, Shanghai, China
| | - Hongmei Yin
- Department of Immunology and Pathogen Biology, Tongji University School of Medicine, Shanghai, China
| | - Hong Yin
- The State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Gansu, China
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21
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Osterloh A. Immune response against rickettsiae: lessons from murine infection models. Med Microbiol Immunol 2017; 206:403-417. [PMID: 28770333 PMCID: PMC5664416 DOI: 10.1007/s00430-017-0514-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 07/20/2017] [Indexed: 12/19/2022]
Abstract
Rickettsiae are small intracellular bacteria that can cause life-threatening febrile diseases. Rickettsioses occur worldwide with increasing incidence. Therefore, a vaccine is highly desired. A prerequisite for the development of a vaccine is the knowledge of the immune response against these bacteria, in particular protective immunity. In recent years murine models of rickettsial infections have been established, and the study of immune response against rickettsiae in mice provided many new insights into protective and pathological immune reactions. This review summarizes the current knowledge about immune mechanisms in protection and pathology in rickettsial infections.
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Affiliation(s)
- Anke Osterloh
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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22
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MyD88 gene knockout attenuates paraquat-induced acute lung injury. Toxicol Lett 2017; 269:41-46. [DOI: 10.1016/j.toxlet.2017.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/17/2017] [Accepted: 01/21/2017] [Indexed: 12/19/2022]
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Wang X, Shaw DK, Hammond HL, Sutterwala FS, Rayamajhi M, Shirey KA, Perkins DJ, Bonventre JV, Velayutham TS, Evans SM, Rodino KG, VieBrock L, Scanlon KM, Carbonetti NH, Carlyon JA, Miao EA, McBride JW, Kotsyfakis M, Pedra JHF. The Prostaglandin E2-EP3 Receptor Axis Regulates Anaplasma phagocytophilum-Mediated NLRC4 Inflammasome Activation. PLoS Pathog 2016; 12:e1005803. [PMID: 27482714 PMCID: PMC4970705 DOI: 10.1371/journal.ppat.1005803] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 07/11/2016] [Indexed: 01/21/2023] Open
Abstract
Rickettsial agents are sensed by pattern recognition receptors but lack pathogen-associated molecular patterns commonly observed in facultative intracellular bacteria. Due to these molecular features, the order Rickettsiales can be used to uncover broader principles of bacterial immunity. Here, we used the bacterium Anaplasma phagocytophilum, the agent of human granulocytic anaplasmosis, to reveal a novel microbial surveillance system. Mechanistically, we discovered that upon A. phagocytophilum infection, cytosolic phospholipase A2 cleaves arachidonic acid from phospholipids, which is converted to the eicosanoid prostaglandin E2 (PGE2) via cyclooxygenase 2 (COX2) and the membrane associated prostaglandin E synthase-1 (mPGES-1). PGE2-EP3 receptor signaling leads to activation of the NLRC4 inflammasome and secretion of interleukin (IL)-1β and IL-18. Importantly, the receptor-interacting serine/threonine-protein kinase 2 (RIPK2) was identified as a major regulator of the immune response against A. phagocytophilum. Accordingly, mice lacking COX2 were more susceptible to A. phagocytophilum, had a defect in IL-18 secretion and exhibited splenomegaly and damage to the splenic architecture. Remarkably, Salmonella-induced NLRC4 inflammasome activation was not affected by either chemical inhibition or genetic ablation of genes associated with PGE2 biosynthesis and signaling. This divergence in immune circuitry was due to reduced levels of the PGE2-EP3 receptor during Salmonella infection when compared to A. phagocytophilum. Collectively, we reveal the existence of a functionally distinct NLRC4 inflammasome illustrated by the rickettsial agent A. phagocytophilum.
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Affiliation(s)
- Xiaowei Wang
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Dana K. Shaw
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Holly L. Hammond
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Fayyaz S. Sutterwala
- Division of Infectious Diseases, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Manira Rayamajhi
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kari Ann Shirey
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Darren J. Perkins
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Joseph V. Bonventre
- Renal Division, Brigham and Women’s Hospital, Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Thangam S. Velayutham
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Sean M. Evans
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - Kyle G. Rodino
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - Lauren VieBrock
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - Karen M. Scanlon
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Nicholas H. Carbonetti
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jason A. Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, United States of America
| | - Edward A. Miao
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Michail Kotsyfakis
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Budweis, Czech Republic
| | - Joao H. F. Pedra
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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