scholarly journals In Vivo Transcriptional Profiling of Yersinia pestis Reveals a Novel Bacterial Mediator of Pulmonary Inflammation

mBio ◽  
2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Roger D. Pechous ◽  
Christopher A. Broberg ◽  
Nikolas M. Stasulli ◽  
Virginia L. Miller ◽  
William E. Goldman
Keyword(s):  
Yersinia Pestis ◽  
Inflammatory Responses ◽  
Severe Pneumonia ◽  
Sudden Onset ◽  
Host Factors ◽  
Respiratory Pathogen ◽  
Bacterial Survival ◽  
Pneumonic Plague ◽  
Content Type

ABSTRACTInhalation ofYersinia pestisresults in primary pneumonic plague, a highly lethal and rapidly progressing necrotizing pneumonia. The disease begins with a period of extensive bacterial replication in the absence of disease symptoms, followed by the sudden onset of inflammatory responses that ultimately prove fatal. Very little is known about the bacterial and host factors that contribute to the rapid biphasic progression of pneumonic plague. In this work, we analyzed thein vivotranscription kinetics of 288 bacterial open reading frames previously shown by microarray analysis to be dynamically regulated in the lung. Using this approach combined with bacterial genetics, we were able to identify five Y. pestis genes that contribute to the development of pneumonic plague. Deletion of one of these genes,ybtX, did not alter bacterial survival but attenuated host inflammatory responses during late-stage disease. Deletion ofybtXin another lethal respiratory pathogen,Klebsiella pneumoniae, also resulted in diminished host inflammation during infection. Thus, ourin vivotranscriptional screen has identified an important inflammatory mediator that is common to two Gram-negative bacterial pathogens that cause severe pneumonia.IMPORTANCEYersinia pestis is responsible for at least three major pandemics, most notably the Black Death of the Middle Ages. Due to its pandemic potential, ease of dissemination by aerosolization, and a history of its weaponization, Y. pestis is categorized by the Centers for Disease Control and Prevention as a tier 1 select agent most likely to be used as a biological weapon. To date, there is no licensed vaccine against Y. pestis. Importantly, an early “silent” phase followed by the rapid onset of nondescript influenza-like symptoms makes timely treatment of pneumonic plague difficult. A more detailed understanding of the bacterial and host factors that contribute to pathogenesis is essential to understanding the progression of pneumonic plague and developing or enhancing treatment options.

scholarly journals Combinational Deletion of Three Membrane Protein-Encoding Genes Highly Attenuates Yersinia pestis while Retaining Immunogenicity in a Mouse Model of Pneumonic Plague

2015 ◽  
Vol 83 (4) ◽  
pp. 1318-1338 ◽  
Author(s):  
Bethany L. Tiner ◽  
Jian Sha ◽  
Michelle L. Kirtley ◽  
Tatiana E. Erova ◽  
Vsevolod L. Popov ◽  
...  
Keyword(s):  
Mouse Model ◽  
Yersinia Pestis ◽  
Double Mutant ◽  
Lethal Dose ◽  
Bactericidal Effect ◽  
Alveolar Epithelial Cells ◽  
Triple Mutant ◽  
Pneumonic Plague ◽  
Content Type

Previously, we showed that deletion of genes encoding Braun lipoprotein (Lpp) and MsbB attenuatedYersinia pestisCO92 in mouse and rat models of bubonic and pneumonic plague. While Lpp activates Toll-like receptor 2, the MsbB acyltransferase modifies lipopolysaccharide. Here, we deleted theailgene (encoding theattachment-invasionlocus) from wild-type (WT) strain CO92 or itslppsingle and ΔlppΔmsbBdouble mutants. While the Δailsingle mutant was minimally attenuated compared to the WT bacterium in a mouse model of pneumonic plague, the ΔlppΔaildouble mutant and the ΔlppΔmsbBΔailtriple mutant were increasingly attenuated, with the latter being unable to kill mice at a 50% lethal dose (LD50) equivalent to 6,800 LD50s of WT CO92. The mutant-infected animals developed balanced TH1- and TH2-based immune responses based on antibody isotyping. The triple mutant was cleared from mouse organs rapidly, with concurrent decreases in the production of various cytokines and histopathological lesions. When surviving animals infected with increasing doses of the triple mutant were subsequently challenged on day 24 with the bioluminescent WT CO92 strain (20 to 28 LD50s), 40 to 70% of the mice survived, with efficient clearing of the invading pathogen, as visualized in real time byin vivoimaging. The rapid clearance of the triple mutant, compared to that of WT CO92, from animals was related to the decreased adherence and invasion of human-derived HeLa and A549 alveolar epithelial cells and to its inability to survive intracellularly in these cells as well as in MH-S murine alveolar and primary human macrophages. An early burst of cytokine production in macrophages elicited by the triple mutant compared to WT CO92 and the mutant's sensitivity to the bactericidal effect of human serum would further augment bacterial clearance. Together, deletion of theailgene from the ΔlppΔmsbBdouble mutant severely attenuatedY. pestisCO92 to evoke pneumonic plague in a mouse model while retaining the required immunogenicity needed for subsequent protection against infection.

scholarly journals Spatially Distinct Neutrophil Responses within the Inflammatory Lesions of Pneumonic Plague

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Nikolas M. Stasulli ◽  
Kara R. Eichelberger ◽  
Paul A. Price ◽  
Roger D. Pechous ◽  
Stephanie A. Montgomery ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Cell Types ◽  
Lung Lesions ◽  
Pneumonic Plague ◽  
Content Type ◽  
Microbe Interactions ◽  
Host Microbe Interactions ◽  
Neutrophil Survival

ABSTRACTDuring pneumonic plague, the bacteriumYersinia pestiselicits the development of inflammatory lung lesions that continue to expand throughout infection. This lesion development and persistence are poorly understood. Here, we examine spatially distinct regions of lung lesions using laser capture microdissection and transcriptome sequencing (RNA-seq) analysis to identify transcriptional differences between lesion microenvironments. We show that cellular pathways involved in leukocyte migration and apoptosis are downregulated in the center of lung lesions compared to the periphery. Probing for the bacterial factor(s) important for the alteration in neutrophil survival, we show bothin vitroandin vivothatY. pestisincreases neutrophil survival in a manner that is dependent on the type III secretion system effector YopM. This research explores the complexity of spatially distinct host-microbe interactions and emphasizes the importance of cell relevance in assays in order to fully understandY. pestisvirulence.IMPORTANCEYersinia pestisis a high-priority pathogen and continues to cause outbreaks worldwide. The ability ofY. pestisto be transmitted via respiratory droplets and its history of weaponization has led to its classification as a select agent most likely to be used as a biological weapon. Unrestricted bacterial growth during the initial preinflammatory phase primes patients to be infectious once disease symptoms begin in the proinflammatory phase, and the rapid disease progression can lead to death beforeY. pestisinfection can be diagnosed and treated. Usingin vivoanalyses and focusing on relevant cell types during pneumonic plague infection, we can identify host pathways that may be manipulated to extend the treatment window for pneumonic plague patients.

scholarly journals Inactivation of Peroxiredoxin 6 by the Pla Protease of Yersinia pestis

2015 ◽  
Vol 84 (1) ◽  
pp. 365-374 ◽  
Author(s):  
Daniel L. Zimbler ◽  
Justin L. Eddy ◽  
Jay A. Schroeder ◽  
Wyndham W. Lathem
Keyword(s):  
Yersinia Pestis ◽  
Lung Damage ◽  
Rapid Progression ◽  
Dependent Manner ◽  
Wild Type ◽  
Peroxiredoxin 6 ◽  
Pneumonic Plague ◽  
Content Type

Pneumonic plague represents the most severe form of disease caused byYersinia pestisdue to its ease of transmission, rapid progression, and high mortality rate. TheY. pestisouter membrane Pla protease is essential for the development of pneumonic plague; however, the complete repertoire of substrates cleaved by Pla in the lungs is not known. In this study, we describe a proteomic screen to identify host proteins contained within the bronchoalveolar lavage fluid of mice that are cleaved and/or processed byY. pestisin a Pla-dependent manner. We identified peroxiredoxin 6 (Prdx6), a host factor that contributes to pulmonary surfactant metabolism and lung defense against oxidative stress, as a previously unknown substrate of Pla. Pla cleaves Prdx6 at three distinct sites, and these cleavages disrupt both the peroxidase and phospholipase A2activities of Prdx6. In addition, we found that infection with wild-typeY. pestisreduces the abundance of extracellular Prdx6 in the lungs compared to that after infection with ΔplaY. pestis, suggesting that Pla cleaves Prdx6 in the pulmonary compartment. However, following infection with either wild-type or Δpla Y. pestis, Prdx6-deficient mice exhibit no differences in bacterial burden, host immune response, or lung damage from wild-type mice. Thus, while Pla is able to disrupt Prdx6 functionin vitroand reduce Prdx6 levelsin vivo, the cleavage of Prdx6 has little detectable impact on the progression or outcome of pneumonic plague.

scholarly journals Tn-Seq Analysis Identifies Genes Important for Yersinia pestis Adherence during Primary Pneumonic Plague

mSphere ◽  
2020 ◽  
Vol 5 (4) ◽  
Author(s):  
Kara R. Eichelberger ◽  
Victoria E. Sepúlveda ◽  
John Ford ◽  
Sara R. Selitsky ◽  
Piotr A. Mieczkowski ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Subsequent Development ◽  
Transcriptional Analysis ◽  
Minor Effect ◽  
Wild Type ◽  
Single Strain ◽  
Pneumonic Plague ◽  
Content Type

ABSTRACT Following inhalation, Yersinia pestis rapidly colonizes the lung to establish infection during primary pneumonic plague. Although several adhesins have been identified in Yersinia spp., the factors mediating early Y. pestis adherence in the lung remain unknown. To identify genes important for Y. pestis adherence during primary pneumonic plague, we used transposon insertion sequencing (Tn-seq). Wild-type and capsule mutant (Δcaf1) Y. pestis transposon mutant libraries were serially passaged in vivo to enrich for nonadherent mutants in the lung using a mouse model of primary pneumonic plague. Sequencing of the passaged libraries revealed six mutants that were significantly enriched in both the wild-type and Δcaf1 Y. pestis backgrounds. The enriched mutants had insertions in genes that encode transcriptional regulators, chaperones, an endoribonuclease, and YPO3903, a hypothetical protein. Using single-strain infections and a transcriptional analysis, we identified a significant role for YPO3903 in Y. pestis adherence in the lung and showed that YPO3903 regulated transcript levels of psaA, which encodes a fimbria previously implicated in Y. pestis adherence in vitro. Deletion of psaA had a minor effect on Y. pestis adherence in the lung, suggesting that YPO3903 regulates other adhesins in addition to psaA. By enriching for mutations in genes that regulate the expression or assembly of multiple genes or proteins, we obtained screen results indicating that there may be not just one dominant adhesin but rather several factors that contribute to early Y. pestis adherence during primary pneumonic plague. IMPORTANCE Colonization of the lung by Yersinia pestis is a critical first step in establishing infection during primary pneumonic plague, a disease characterized by high lethality. However, the mechanisms by which Y. pestis adheres in the lung after inhalation remain elusive. Here, we used Tn-seq to identify Y. pestis genes important for adherence early during primary pneumonic plague. Our mutant enrichment strategy resulted in the identification of genes important for regulation and assembly of genes and proteins rather than adhesin genes themselves. These results reveal that there may be multiple Y. pestis adhesins or redundancy among adhesins. Identifying the adhesins regulated by the genes identified in our enrichment screen may reveal novel therapeutic targets for preventing Y. pestis adherence and the subsequent development of pneumonic plague.

scholarly journals Mycobacterium tuberculosis Alters the Metalloprotease Activity of the COP9 Signalosome

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Lia Danelishvili ◽  
Lmar Babrak ◽  
Sasha J. Rose ◽  
Jamie Everman ◽  
Luiz E. Bermudez
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cop9 Signalosome ◽  
Virulence Determinants ◽  
Bacterial Survival ◽  
Phagocytic Cells ◽  
Content Type ◽  
Metalloprotease Activity ◽  
Macrophage Protein

ABSTRACT Inhibition of apoptotic death of macrophages by Mycobacterium tuberculosis represents an important mechanism of virulence that results in pathogen survival both in vitro and in vivo. To identify M. tuberculosis virulence determinants involved in the modulation of apoptosis, we previously screened a transposon bank of mutants in human macrophages, and an M. tuberculosis clone with a nonfunctional Rv3354 gene was identified as incompetent to suppress apoptosis. Here, we show that the Rv3354 gene encodes a protein kinase that is secreted within mononuclear phagocytic cells and is required for M. tuberculosis virulence. The Rv3354 effector targets the metalloprotease (JAMM) domain within subunit 5 of the COP9 signalosome (CSN5), resulting in suppression of apoptosis and in the destabilization of CSN function and regulatory cullin-RING ubiquitin E3 enzymatic activity. Our observation suggests that alteration of the metalloprotease activity of CSN by Rv3354 possibly prevents the ubiquitin-dependent proteolysis of M. tuberculosis-secreted proteins. IMPORTANCE Macrophage protein degradation is regulated by a protein complex called a signalosome. One of the signalosomes associated with activation of ubiquitin and protein labeling for degradation was found to interact with a secreted protein from M. tuberculosis, which binds to the complex and inactivates it. The interference with the ability to inactivate bacterial proteins secreted in the phagocyte cytosol may have crucial importance for bacterial survival within the phagocyte.

scholarly journals Inhibition of Neutrophil Primary Granule Release during Yersinia pestis Pulmonary Infection

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Kara R. Eichelberger ◽  
Grant S. Jones ◽  
William E. Goldman
Keyword(s):  
Yersinia Pestis ◽  
Critical Role ◽  
Immune Defense ◽  
Calcium Flux ◽  
Human Neutrophils ◽  
Pneumonic Plague ◽  
Content Type ◽  
Neutrophil Degranulation ◽  
Primary Granule ◽  
Granule Release

ABSTRACT Inhalation of Yersinia pestis causes primary pneumonic plague, the most severe manifestation of plague that is characterized by a dramatic neutrophil influx to the lungs. Neutrophils are ineffective during primary pneumonic plague, failing to control Y. pestis growth in the airways. However, the mechanisms by which Y. pestis resists neutrophil killing are incompletely understood. Here, we show that Y. pestis inhibits neutrophil degranulation, an important line of host innate immune defense. We observed that neutrophils from the lungs of mice infected intranasally with Y. pestis fail to release primary granules throughout the course of disease. Using a type III secretion system (T3SS) injection reporter strain, we determined that Y. pestis directly inhibits neutrophil granule release by a T3SS-dependent mechanism. Combinatorial mutant analysis revealed that a Y. pestis strain lacking both effectors YopE and YopH did not inhibit primary granule release and is killed by neutrophils both in vivo and in vitro. Similarly, Y. pestis strains injecting only YopE or YopH are able to inhibit the majority of primary granule release from human neutrophils. We determined that YopE and YopH block Rac2 activation and calcium flux, respectively, to inhibit neutrophil primary granule release in isolated human neutrophils. These results demonstrate that Y. pestis coordinates the inhibition of neutrophil primary granule release through the activities of two distinct effectors, and this inhibition promotes Y. pestis survival during primary pneumonic plague. IMPORTANCE Yersinia pestis is the causative agent of plague and is one of the deadliest human pathogens. The pneumonic form of Y. pestis infection has played a critical role in the severity of both historical and modern plague outbreaks, yet the host-pathogen interactions that govern the lethality of Yersinia pestis pulmonary infections are incompletely understood. Here, we report that Yersinia pestis inhibits neutrophil degranulation during infection, rendering neutrophils ineffective and allowing unrestricted growth of Y. pestis in the lungs. This coordinated inhibition of granule release not only demonstrates the pathogenic benefit of “silencing” lung neutrophils but also reveals specific host processes and pathways that could be manipulated to reduce the severity of primary pneumonic plague.

scholarly journals Identification of Pneumococcal Factors Affecting Pneumococcal Shedding Shows that thedltLocus Promotes Inflammation and Transmission

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
M. Ammar Zafar ◽  
Alexandria J. Hammond ◽  
Shigeto Hamaguchi ◽  
Weisheng Wu ◽  
Masamitsu Kono ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Respiratory Tract ◽  
Capsular Polysaccharide ◽  
Inflammatory Responses ◽  
Transposon Mutagenesis ◽  
Respiratory Pathogen ◽  
Invasive Infection ◽  
Upper Respiratory Tract ◽  
Content Type ◽  
Upper Respiratory

ABSTRACTHost-to-host transmission is a necessary but poorly understood aspect of microbial pathogenesis. Herein, we screened a genomic library of mutants of the leading respiratory pathogenStreptococcus pneumoniaegenerated by mariner transposon mutagenesis (Tn-Seq) to identify genes contributing to its exit or shedding from the upper respiratory tract (URT), the limiting step in the organism’s transmission in an infant mouse model. Our analysis focused on genes affecting the bacterial surface that directly impact interactions with the host. Among the multiple factors identified was thedltlocus, which addsd-alanine onto lipoteichoic acids (LTA) and thereby increases Toll-like receptor 2-mediated inflammation and resistance to antimicrobial peptides. The more robust proinflammatory response in the presence ofd-alanylation promotes secretions that facilitate pneumococcal shedding and allows for transmission. Expression of thedltlocus is controlled by the CiaRH system, which senses cell wall stress in response to antimicrobial activity, including in response to lysozyme, the most abundant antimicrobial along the URT mucosa. Accordingly, in alysM−/−host, there was no longer an effect of thedltlocus on pneumococcal shedding. Thus, our findings demonstrate how a pathogen senses the URT milieu and then modifies its surface characteristics to take advantage of the host response for transit to another host.IMPORTANCEStreptococcus pneumoniae(the pneumococcus) is a common cause of respiratory tract and invasive infection. The overall effectiveness of immunization with the organism’s capsular polysaccharide depends on its ability to block colonization of the upper respiratory tract and thereby prevent host-to-host transmission. Because of the limited coverage of current pneumococcal vaccines, we carried out an unbiasedin vivotransposon mutagenesis screen to identify pneumococcal factors other than its capsular polysaccharide that affect transmission. One such candidate was expressed by thedltlocus, previously shown to addd-alanine onto the pneumococcal lipoteichoic acid present on the bacterial cell surface. This modification protects against host antimicrobials and augments host inflammatory responses. The latter increases secretions and bacterial shedding from the upper respiratory tract to allow for transmission. Thus, this study provides insight into a mechanism employed by the pneumococcus to successfully transit from one host to another.

scholarly journals Na+/H+Antiport Is Essential for Yersinia pestis Virulence

2013 ◽  
Vol 81 (9) ◽  
pp. 3163-3172 ◽  
Author(s):  
Yusuke Minato ◽  
Amit Ghosh ◽  
Wyatt J. Faulkner ◽  
Erin J. Lind ◽  
Sara Schesser Bartra ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Drug Target ◽  
Deletion Mutant ◽  
Ex Vivo ◽  
Ion Homeostasis ◽  
Content Type ◽  
Double Deletion ◽  
Derivative Strain

ABSTRACTNa+/H+antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na+/H+antiport inYersinia pestisvirulence and found thatY. pestisstrains lacking the major Na+/H+antiporters, NhaA and NhaB, are completely attenuated in anin vivomodel of plague. TheY. pestisderivative strain lacking thenhaAandnhaBgenes showed markedly decreased survival in blood and blood serumex vivo. Complementation of eithernhaAornhaBintransrestored the survival of theY. pestis nhaA nhaBdouble deletion mutant in blood. ThenhaA nhaBdouble deletion mutant also showed inhibited growth in an artificial serum medium, Opti-MEM, and a rich LB-based medium with Na+levels and pH values similar to those for blood. Taken together, these data strongly suggest that intact Na+/H+antiport is indispensable for the survival ofY. pestisin the bloodstreams of infected animals and thus might be regarded as a promising noncanonical drug target for infections caused byY. pestisand possibly for those caused by other blood-borne bacterial pathogens.

scholarly journals Redundant Catalases Detoxify Phagocyte Reactive Oxygen and Facilitate Histoplasma capsulatum Pathogenesis

2013 ◽  
Vol 81 (7) ◽  
pp. 2334-2346 ◽  
Author(s):  
Eric D. Holbrook ◽  
Katherine A. Smolnycki ◽  
Brian H. Youseff ◽  
Chad A. Rappleye
Keyword(s):  
Immune System ◽  
Innate Immune System ◽  
Histoplasma Capsulatum ◽  
Reactive Oxygen ◽  
Innate Immune ◽  
Respiratory Pathogen ◽  
Human Neutrophils ◽  
Content Type

ABSTRACTHistoplasma capsulatumis a respiratory pathogen that infects phagocytic cells. The mechanisms allowingHistoplasmato overcome toxic reactive oxygen molecules produced by the innate immune system are an integral part ofHistoplasma's ability to survive during infection. To probe the contribution ofHistoplasmacatalases in oxidative stress defense, we created and analyzed the virulence defects of mutants lacking CatB and CatP, which are responsible for extracellular and intracellular catalase activities, respectively. Both CatB and CatP protectedHistoplasmafrom peroxide challengein vitroand from antimicrobial reactive oxygen produced by human neutrophils and activated macrophages. Optimal protection required both catalases, as the survival of a double mutant lacking both CatB and CatP was lower than that of single-catalase-deficient cells. Although CatB contributed to reactive oxygen species defensesin vitro, CatB was dispensable for lung infection and extrapulmonary disseminationin vivo. Loss of CatB from a strain also lacking superoxide dismutase (Sod3) did not further reduce the survival ofHistoplasmayeasts. Nevertheless, some catalase function was required for pathogenesis since simultaneous loss of both CatB and CatP attenuatedHistoplasmavirulencein vivo. These results demonstrate thatHistoplasma's dual catalases comprise a system that enablesHistoplasmato efficiently overcome the reactive oxygen produced by the innate immune system.

scholarly journals Acidosis Potentiates the Host Proinflammatory Interleukin-1β Response to Pseudomonas aeruginosa Infection

2014 ◽  
Vol 82 (11) ◽  
pp. 4689-4697 ◽  
Author(s):  
Iviana M. Torres ◽  
Yash R. Patankar ◽  
Tamer B. Shabaneh ◽  
Emily Dolben ◽  
Deborah A. Hogan ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Inflammatory Response ◽  
Inflammatory Responses ◽  
Interleukin 1Β ◽  
Acidic Environment ◽  
Content Type ◽  
Inflammatory Damage ◽  
Pseudomonas Aeruginosa Infection ◽  
Peritonitis Model

ABSTRACTInfection byPseudomonas aeruginosa, and bacteria in general, frequently promotes acidification of the local microenvironment, and this is reinforced by pulmonary exertion and exacerbation. However, the consequence of an acidic environment on the host inflammatory response toP. aeruginosainfection is poorly understood. Here we report that the pivotal cellular and host proinflammatory interleukin-1β (IL-1β) response, which enables host clearance of the infection but can produce collateral inflammatory damage, is increased in response toP. aeruginosainfection within an acidic environment. Synergistic mechanisms that promote increased IL-1β release in response toP. aeruginosainfection in an acidic environment are increased pro-IL-1β induction and increased caspase-1 activity, the latter being dependent upon a functional type III secretion system of the bacteria and the NLRC4 inflammasome of the host. Using anin vivoperitonitis model, we have validated that the IL-1β inflammatory response is increased in mice in response toP. aeruginosainfection within an acidic microenvironment. These data reveal novel insights into the regulation and exacerbation of inflammatory responses toP. aeruginosa.

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