scholarly journals MetR-Regulated Vibrio cholerae Metabolism Is Required for Virulence

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Ryan W. Bogard ◽  
Bryan W. Davies ◽  
John J. Mekalanos
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Virulence Factor ◽  
Current Knowledge ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Content Type ◽  
Mouse Intestine

ABSTRACTLysR-type transcriptional regulators (LTTRs) are the largest, most diverse family of prokaryotic transcription factors, with regulatory roles spanning metabolism, cell growth and division, and pathogenesis. Using a sequence-defined transposon mutant library, we screened a panel ofV. choleraeEl Tor mutants to identify LTTRs required for host intestinal colonization. Surprisingly, out of 38 LTTRs, only one severely affected intestinal colonization in the suckling mouse model of cholera: the methionine metabolism regulator, MetR. Genetic analysis of genes influenced by MetR revealed thatglyA1andmetJwere also required for intestinal colonization. Chromatin immunoprecipitation of MetR and quantitative reverse transcription-PCR (qRT-PCR) confirmed interaction with and regulation ofglyA1, indicating that misregulation ofglyA1is likely responsible for the colonization defect observed in themetRmutant. TheglyA1mutant was auxotrophic for glycine but exhibited wild-type trimethoprim sensitivity, making folate deficiency an unlikely cause of its colonization defect. MetJ regulatory mutants are not auxotrophic but are likely altered in the regulation of amino acid-biosynthetic pathways, including those for methionine, glycine, and serine, and this misregulation likely explains its colonization defect. However, mutants defective in methionine, serine, and cysteine biosynthesis exhibited wild-type virulence, suggesting that these amino acids can be scavenged in vivo. Taken together, our results suggest that glycine biosynthesis may be required to alleviate an in vivo nutritional restriction in the mouse intestine; however, additional roles for glycine may exist. Irrespective of the precise nature of this requirement, this study illustrates the importance of pathogen metabolism, and the regulation thereof, as a virulence factor.IMPORTANCEVibrio choleraecontinues to be a severe cause of morbidity and mortality in developing countries. Identification ofV. choleraefactors critical to disease progression offers the potential to develop or improve upon therapeutics and prevention strategies. To increase the efficiency of virulence factor discovery, we employed a regulator-centric approach to multiplex our in vivo screening capabilities and allow whole regulons inV. choleraeto be interrogated for pathogenic potential. We identified MetR as a new virulence regulator and serine hydroxymethyltransferase GlyA1 as a new MetR-regulated virulence factor, both required byV. choleraeto colonize the infant mouse intestine. Bacterial metabolism is a prerequisite to virulence, and current knowledge of in vivo metabolism of pathogens is limited. Here, we expand the known role of amino acid metabolism and regulation in virulence and offer new insights into the in vivo metabolic requirements ofV. choleraewithin the mouse intestine.

scholarly journals Aerobactin, but Not Yersiniabactin, Salmochelin, or Enterobactin, Enables the Growth/Survival of Hypervirulent (Hypermucoviscous) Klebsiella pneumoniaeEx VivoandIn Vivo

2015 ◽  
Vol 83 (8) ◽  
pp. 3325-3333 ◽  
Author(s):  
Thomas A. Russo ◽  
Ruth Olson ◽  
Ulrike MacDonald ◽  
Janet Beanan ◽  
Bruce A. Davidson
Keyword(s):  
Virulence Factor ◽  
Human Urine ◽  
Ex Vivo ◽  
Systemic Infection ◽  
Relative Activity ◽  
Ascites Fluid ◽  
Specific Gene ◽  
Wild Type ◽  
Content Type

The siderophore aerobactin is the dominant siderophore produced by hypervirulentKlebsiella pneumoniae(hvKP) and was previously shown to be a major virulence factor in systemic infection. However, strains of hvKP commonly produce the additional siderophores yersiniabactin, salmochelin, and enterobactin. The roles of these siderophores in hvKP infection have not been optimally defined. To that end, site-specific gene disruptions were created in hvKP1 (wild type), resulting in the generation of hvKP1ΔiucA(aerobactin deficient), hvKP1ΔiroB(salmochelin deficient), hvKP1ΔentB(enterobactin and salmochelin deficient), hvKP1Δirp2(yersiniabactin deficient), and hvKP1ΔentBΔirp2(enterobactin, salmochelin, and yersiniabactin deficient). The growth/survival of these constructs was compared to that of their wild-type parent hvKP1ex vivoin human ascites fluid, human serum, and human urine andin vivoin mouse systemic infection and pulmonary challenge models. Interestingly, in contrast to aerobactin, the inability to produce enterobactin, salmochelin, or yersiniabactin individually or in combination did not decrease theex vivogrowth/survival in human ascites or serum or decrease virulence in thein vivoinfection models. Surprisingly, none of the siderophores increased growth in human urine. In human ascites fluid supplemented with exogenous siderophores, siderophores increased the growth of hvKP1ΔiucA, with the relative activity being enterobactin > aerobactin > yersiniabactin > salmochelin, suggesting that the contribution of aerobactin to virulence is dependent on both innate biologic activity and quantity produced. Taken together, these data confirm and extend a role for aerobactin as a critical virulence factor for hvKP. Since it appears that aerobactin production is a defining trait of hvKP strains, this factor is a potential antivirulence target.

scholarly journals Mutation in the relA Gene of Vibrio cholerae Affects In Vitro and In Vivo Expression of Virulence Factors

2003 ◽  
Vol 185 (16) ◽  
pp. 4672-4682 ◽  
Author(s):  
Shruti Haralalka ◽  
Suvobroto Nandi ◽  
Rupak K. Bhadra
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Mutant Strain ◽  
Virulence Factors ◽  
Antibiotic Production ◽  
Wild Type ◽  
Altered Expression ◽  
Transcript Levels

ABSTRACT The relA gene product determines the level of (p)ppGpp, the effector nucleotides of the bacterial stringent response that are also involved in the regulation of other functions, like antibiotic production and quorum sensing. In order to explore the possible involvement of relA in the regulation of virulence of Vibrio cholerae, a relA homolog from the organism (relA VCH) was cloned and sequenced. The relA VCH gene encodes a 738-amino-acid protein having functions similar to those of other gram-negative bacteria, including Escherichia coli. A ΔrelA::kan allele was generated by replacing ∼31% of the open reading frame of wild-type relA of V. cholerae El Tor strain C6709 with a kanamycin resistance gene. The V. cholerae relA mutant strain thus generated, SHK17, failed to accumulate (p)ppGpp upon amino acid deprivation. Interestingly, compared to the wild type, C6709, the mutant strain SHK17 exhibited significantly reduced in vitro production of two principal virulence factors, cholera toxin (CT) and toxin-coregulated pilus (TCP), under virulence gene-inducing conditions. In vivo experiments carried out in rabbit ileal loop and suckling mouse models also confirmed our in vitro results. The data suggest that (p)ppGpp is essential for maximal expression of CT and TCP during in vitro growth, as well as during intestinal infection by virulent V. cholerae. Northern blot and reverse transcriptase PCR analyses indicated significant reduction in the transcript levels of both virulence factors in the relA mutant strain SHK17. Such marked alteration of virulence phenotypes in SHK17 appears most likely to be due to down regulation of transcript levels of toxR and toxT, the two most important virulence regulatory genes of V. cholerae. In SHK17, the altered expression of the two outer membrane porin proteins, OmpU and OmpT, indicated that the relA mutation most likely affects the ToxR-dependent virulence regulatory pathway, because it had been shown earlier that ToxR directly regulates their expression independently of ToxT.

scholarly journals The Vibrio parahaemolyticus ToxRS Regulator Is Required for Stress Tolerance and Colonization in a Novel Orogastric Streptomycin-Induced Adult Murine Model

2012 ◽  
Vol 80 (5) ◽  
pp. 1834-1845 ◽  
Author(s):  
W. Brian Whitaker ◽  
Michelle A. Parent ◽  
Aoife Boyd ◽  
Gary P. Richards ◽  
E. Fidelma Boyd
Keyword(s):  
Stress Tolerance ◽  
Murine Model ◽  
Vibrio Parahaemolyticus ◽  
Sodium Dodecyl ◽  
Virulence Gene ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Content Type ◽  
Virulence Gene Expression

ABSTRACTVibrio parahaemolyticus, a marine bacterium, is the causative agent of gastroenteritis associated with the consumption of seafood. It contains a homologue of thetoxRSoperon that inV. choleraeis the key regulator of virulence gene expression. We examined a nonpolar mutation intoxRSto determine the role of these genes inV. parahaemolyticusRIMD2210633, an O3:K6 isolate, and showed that compared to the wild type, ΔtoxRSwas significantly more sensitive to acid, bile salts, and sodium dodecyl sulfate stresses. We demonstrated that ToxRS is a positive regulator ofompUexpression, and that the complementation of ΔtoxRSwithompUrestores stress tolerance. Furthermore, we showed that ToxRS also regulates type III secretion system genes in chromosome I via the regulation of theleuOhomologue VP0350. We examined the effect of ΔtoxRS in vivousing a new orogastric adult murine model of colonization. We demonstrated that streptomycin-treated adult C57BL/6 mice experienced prolonged intestinal colonization along the entire intestinal tract by the streptomycin-resistantV. parahaemolyticus. In contrast, no colonization occurred in non-streptomycin-treated mice. A competition assay between the ΔtoxRSand wild-typeV. parahaemolyticusstrains marked with the β-galactosidase genelacZdemonstrated that the ΔtoxRSstrain was defective in colonization compared to the wild-type strain. This defect was rescued by ectopically expressingompU. Thus, the defect in stress tolerance and colonization in ΔtoxRSis solely due to OmpU. To our knowledge, the orogastric adult murine model reported here is the first showing sustained intestinal colonization byV. parahaemolyticus.

scholarly journals Differential Requirement for PBP1a and PBP1b inIn VivoandIn VitroFitness of Vibrio cholerae

2014 ◽  
Vol 82 (5) ◽  
pp. 2115-2124 ◽  
Author(s):  
Tobias Dörr ◽  
Andrea Möll ◽  
Michael C. Chao ◽  
Felipe Cava ◽  
Hubert Lam ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Vibrio Cholerae ◽  
Synthetic Lethality ◽  
Wild Type ◽  
Content Type ◽  
Infant Mouse ◽  
Mouse Small Intestine ◽  
Membrane Lipoproteins

ABSTRACTWe investigated the roles of theVibrio choleraehigh-molecular-weight bifunctional penicillin binding proteins, PBP1a and PBP1b, in the fitness of this enteric pathogen. Using a screen for synthetic lethality, we found that theV. choleraePBP1a and PBP1b proteins, like theirEscherichia colihomologues, are each essential in the absence of the other and in the absence of the other's putative activator, the outer membrane lipoproteins LpoA and LpoB, respectively. Comparative analyses ofV. choleraemutants suggest that PBP1a/LpoA ofV. choleraeplay a more prominent role in generating and/or maintaining the pathogen's cell wall than PBP1b/LpoB.V. choleraelacking PBP1b or LpoB exhibited wild-type growth under all conditions tested. In contrast,V. choleraelacking PBP1a or LpoA exhibited growth deficiencies in minimal medium, in the presence of deoxycholate and bile, and in competition assays with wild-type cells bothin vitroand in the infant mouse small intestine. PBP1a pathway mutants are particularly impaired in stationary phase, which renders them sensitive to a product(s) present in supernatants from stationary-phase wild-type cells. The marked competitive defect of the PBP1a pathway mutantsin vivowas largely absent when exponential-phase cells rather than stationary-phase cells were used to inoculate suckling mice. Thus, at least forV. choleraePBP1a pathway mutants, the growth phase of the inoculum is a key modulator of infectivity.

scholarly journals Redirection of Metabolism in Response to Fatty Acid Kinase inStaphylococcus aureus

2018 ◽  
Vol 200 (19) ◽  
Author(s):  
Zachary DeMars ◽  
Jeffrey L. Bose
Keyword(s):  
Amino Acids ◽  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Amino Acid ◽  
Virulence Factor ◽  
Tca Cycle ◽  
Acetate Metabolism ◽  
Adenylate Energy Charge ◽  
Wild Type ◽  
Content Type

ABSTRACTStaphylococcus aureusis capable of phosphorylating exogenous fatty acids for incorporation into the bacterium's membrane via the fatty acid kinase, FakA. Additionally, FakA plays a significant role in virulence factor regulation and skin infections. We previously showed that afakAmutant displays altered growth kineticsin vitro, observed during the late-exponential phase of growth. Here, we demonstrate that the absence of FakA leads to key metabolic changes. First, thefakAmutant has an altered acetate metabolism, with acetate being consumed at an increased rate than in the wild-type strain. Moreover, the growth benefit was diminished with inactivation of the acetate-generating enzyme AckA. Using a mass spectrometry-based approach, we identified altered concentrations of tricarboxylic acid (TCA) cycle intermediates and both intracellular and extracellular amino acids. Together, these data demonstrate a change in carbohydrate carbon utilization and altered amino acid metabolism in thefakAmutant. Energy status analysis revealed the mutant had a similar ADP/ATP ratio to that of the wild type, but a reduced adenylate energy charge. The inactivation offakAchanged the NAD+/NADH and NADP+/NADPH ratios, indicating a more oxidized cellular environment. Evidence points to the global metabolic regulatory proteins CcpA and CodY being important contributors to the altered growth in afakAmutant. Indeed, it was found that directing amino acids from the urea cycle into the TCA cycle via glutamate dehydrogenase was an essential component ofS. aureusgrowth after glucose depletion. Together, these data identify a previously unidentified role of FakA in the global physiology ofS. aureus, linking external fatty acid utilization and central metabolism.IMPORTANCEThe fatty acid kinase, FakA, ofStaphylococcus aureusplays several important roles in the cell. FakA is important for the activation of the SaeRS two-component system and secreted virulence factors like α-hemolysin. However, the contribution of FakA to cellular metabolism has not been explored. Here, we highlight the metabolic consequence of removal of FakA from the cell. The absence of FakA leads to altered acetate metabolism and altered redox balance, as well as a change in intracellular amino acids. Additionally, the use of environmental amino acid sources is affected by FakA. Together, these results demonstrate for the first time that FakA provides a link between the pathways for exogenous fatty acid use, virulence factor regulation, and other metabolic processes.

scholarly journals Large-Scale Synonymous Substitutions in Cucumber Mosaic Virus RNA 3 Facilitate Amino Acid Mutations in the Coat Protein

2018 ◽  
Vol 92 (22) ◽  
Author(s):  
Tomofumi Mochizuki ◽  
Rie Ohara ◽  
Marilyn J. Roossinck
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Viral Genome ◽  
Large Scale ◽  
Viral Rna ◽  
Wild Type ◽  
Competitive Fitness ◽  
Content Type ◽  
Synonymous Substitutions ◽  
Cp Gene

ABSTRACTThe effect of large-scale synonymous substitutions in a small icosahedral, single-stranded RNA viral genome on virulence, viral titer, and protein evolution were analyzed. The coat protein (CP) gene of the Fny stain of cucumber mosaic virus (CMV) was modified. We created four CP mutants in which all the codons of nine amino acids in the 5′ or 3′ half of the CP gene were replaced by either the most frequently or the least frequently used synonymous codons in monocot plants. When the dicot host (Nicotiana benthamiana) was inoculated with these four CP mutants, viral RNA titers in uninoculated symptomatic leaves decreased, while all mutants eventually showed mosaic symptoms similar to those for the wild type. The codon adaptation index of these four CP mutants against dicot genes was similar to those of the wild-type CP gene, indicating that the reduction of viral RNA titer was due to deleterious changes of the secondary structure of RNAs 3 and 4. When two 5′ mutants were serially passaged inN. benthamiana, viral RNA titers were rapidly restored but competitive fitness remained decreased. Although no nucleic acid changes were observed in the passaged wild-type CMV, one to three amino acid changes were observed in the synonymously mutated CP of each passaged virus, which were involved in recovery of viral RNA titer of 5′ mutants. Thus, we demonstrated that deleterious effects of the large-scale synonymous substitutions in the RNA viral genome facilitated the rapid amino acid mutation(s) in the CP to restore the viral RNA titer.IMPORTANCERecently, it has been known that synonymous substitutions in RNA virus genes affect viral pathogenicity and competitive fitness by alteration of global or local RNA secondary structure of the viral genome. We confirmed that large-scale synonymous substitutions in the CP gene of CMV resulted in decreased viral RNA titer. Importantly, when viral evolution was stimulated by serial-passage inoculation, viral RNA titer was rapidly restored, concurrent with a few amino acid changes in the CP. This novel finding indicates that the deleterious effects of large-scale nucleic acid mutations on viral RNA secondary structure are readily tolerated by structural changes in the CP, demonstrating a novel part of the adaptive evolution of an RNA viral genome. In addition, our experimental system for serial inoculation of large-scale synonymous mutants could uncover a role for new amino acid residues in the viral protein that have not been observed in the wild-type virus strains.

scholarly journals Quorum Sensing: a Transcriptional Regulatory System Involved in the Pathogenicity of Burkholderia mallei

2004 ◽  
Vol 72 (11) ◽  
pp. 6589-6596 ◽  
Author(s):  
Ricky L. Ulrich ◽  
David DeShazer ◽  
Harry B. Hines ◽  
Jeffrey A. Jeddeloh
Keyword(s):  
Quorum Sensing ◽  
Virulence Factor ◽  
Regulatory System ◽  
In Silico Analysis ◽  
Homoserine Lactone ◽  
Burkholderia Mallei ◽  
Wild Type ◽  
Transcriptional Regulatory ◽  
A Cell

ABSTRACT Numerous gram-negative bacterial pathogens regulate virulence factor expression by using a cell density mechanism termed quorum sensing (QS). An in silico analysis of the Burkholderia mallei ATCC 23344 genome revealed that it encodes at least two luxI and four luxR homologues. Using mass spectrometry, we showed that wild-type B. mallei produces the signaling molecules N-octanoyl-homoserine lactone and N-decanoyl-homoserine lactone. To determine if QS is involved in the virulence of B. mallei, we generated mutations in each putative luxIR homologue and tested the pathogenicities of the derivative strains in aerosol BALB/c mouse and intraperitoneal hamster models. Disruption of the B. mallei QS alleles, especially in RJ16 (bmaII) and RJ17 (bmaI3), which are luxI mutants, significantly reduced virulence, as indicated by the survival of mice who were aerosolized with 104 CFU (10 50% lethal doses [LD50s]). For the B. mallei transcriptional regulator mutants (luxR homologues), mutation of the bmaR5 allele resulted in the most pronounced decrease in virulence, with 100% of the challenged animals surviving a dose of 10 LD50s. Using a Syrian hamster intraperitoneal model of infection, we determined the LD50s for wild-type B. mallei and each QS mutant. An increase in the relative LD50 was found for RJ16 (bmaI1) (>967 CFU), RJ17 (bmaI3) (115 CFU), and RJ20 (bmaR5) (151 CFU) compared to wild-type B. mallei (<13 CFU). These findings demonstrate that B. mallei carries multiple luxIR homologues that either directly or indirectly regulate the biosynthesis of an essential virulence factor(s) that contributes to the pathogenicity of B. mallei in vivo.

scholarly journals Primary structure requirements for correct sorting of the yeast mitochondrial protein ADH III to the yeast mitochondrial matrix space.

1987 ◽  
Vol 7 (1) ◽  
pp. 294-304 ◽  
Author(s):  
D Pilgrim ◽  
E T Young
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Amino Acid ◽  
Proteolytic Processing ◽  
Mitochondrial Matrix ◽  
Wild Type ◽  
Mature Form ◽  
Amino Terminal ◽  
The Matrix

Alcohol dehydrogenase isoenzyme III (ADH III) in Saccharomyces cerevisiae, the product of the ADH3 gene, is located in the mitochondrial matrix. The ADH III protein was synthesized as a larger precursor in vitro when the gene was transcribed with the SP6 promoter and translated with a reticulocyte lysate. A precursor of the same size was detected when radioactively pulse-labeled proteins were immunoprecipitated with anti-ADH antibody. This precursor was rapidly processed to the mature form in vivo with a half-time of less than 3 min. The processing was blocked if the mitochondria were uncoupled with carbonyl cyanide m-chlorophenylhydrazone. Mutant enzymes in which only the amino-terminal 14 or 16 amino acids of the presequence were retained were correctly targeted and imported into the matrix. A mutant enzyme that was missing the amino-terminal 17 amino acids of the presequence produced an active enzyme, but the majority of the enzyme activity remained in the cytoplasmic compartment on cellular fractionation. Random amino acid changes were produced in the wild-type presequence by bisulfite mutagenesis of the ADH3 gene. The resulting ADH III protein was targeted to the mitochondria and imported into the matrix in all of the mutants tested, as judged by enzyme activity. Mutants containing amino acid changes in the carboxyl-proximal half of the ADH3 presequence were imported and processed to the mature form at a slower rate than the wild type, as judged by pulse-chase studies in vivo. The unprocessed precursor appeared to be unstable in vivo. It was concluded that only a small portion of the presequence contains the necessary information for correct targeting and import. Furthermore, the information for correct proteolytic processing of the presequence appears to be distinct from the targeting information and may involve secondary structure information in the presequence.

scholarly journals Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

2011 ◽  
Vol 80 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Chen Li ◽  
Kurniyati ◽  
Bo Hu ◽  
Jiang Bian ◽  
Jianlan Sun ◽  
...  
Keyword(s):  
Porphyromonas Gingivalis ◽  
Biofilm Formation ◽  
Adult Population ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Content Type ◽  
Multiple Organs ◽  
Biochemical Analyses

ABSTRACTThe oral bacteriumPorphyromonas gingivalisis a key etiological agent of human periodontitis, a prevalent chronic disease that affects up to 80% of the adult population worldwide.P. gingivalisexhibits neuraminidase activity. However, the enzyme responsible for this activity, its biochemical features, and its role in the physiology and virulence ofP. gingivalisremain elusive. In this report, we found thatP. gingivalisencodes a neuraminidase, PG0352 (SiaPg). Transcriptional analysis showed thatPG0352is monocistronic and is regulated by a sigma70-like promoter. Biochemical analyses demonstrated that SiaPgis an exo-α-neuraminidase that cleaves glycosidic-linked sialic acids. Cryoelectron microscopy and tomography analyses revealed that thePG0352deletion mutant (ΔPG352) failed to produce an intact capsule layer. Compared to the wild type,in vitrostudies showed that ΔPG352 formed less biofilm and was less resistant to killing by the host complement.In vivostudies showed that while the wild type caused a spreading type of infection that affected multiple organs and all infected mice were killed, ΔPG352 only caused localized infection and all animals survived. Taken together, these results demonstrate that SiaPgis an important virulence factor that contributes to the biofilm formation, capsule biosynthesis, and pathogenicity ofP. gingivalis, and it can potentially serve as a new target for developing therapeutic agents againstP. gingivalisinfection.

scholarly journals Systems Modeling of the Role of Interleukin-21 in the Maintenance of Effector CD4+ T Cell Responses during Chronic Helicobacter pylori Infection

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Adria Carbo ◽  
Danyvid Olivares-Villagómez ◽  
Raquel Hontecillas ◽  
Josep Bassaganya-Riera ◽  
Rupesh Chaturvedi ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
T Cell ◽  
Wild Type ◽  
Content Type ◽  
Interleukin 21 ◽  
H Pylori ◽  
Deficient Mice

ABSTRACTThe development of gastritis duringHelicobacter pyloriinfection is dependent on an activated adaptive immune response orchestrated by T helper (Th) cells. However, the relative contributions of the Th1 and Th17 subsets to gastritis and control of infection are still under investigation. To investigate the role of interleukin-21 (IL-21) in the gastric mucosa duringH. pyloriinfection, we combined mathematical modeling of CD4+T cell differentiation within vivomechanistic studies. We infected IL-21-deficient and wild-type mice withH. pyloristrain SS1 and assessed colonization, gastric inflammation, cellular infiltration, and cytokine profiles. ChronicallyH. pylori-infected IL-21-deficient mice had higherH. pyloricolonization, significantly less gastritis, and reduced expression of proinflammatory cytokines and chemokines compared to these parameters in infected wild-type littermates. Thesein vivodata were used to calibrate anH. pyloriinfection-dependent, CD4+T cell-specific computational model, which then described the mechanism by which IL-21 activates the production of interferon gamma (IFN-γ) and IL-17 during chronicH. pyloriinfection. The model predicted activated expression of T-bet and RORγt and the phosphorylation of STAT3 and STAT1 and suggested a potential role of IL-21 in the modulation of IL-10. Driven by our modeling-derived predictions, we found reduced levels of CD4+splenocyte-specifictbx21androrcexpression, reduced phosphorylation of STAT1 and STAT3, and an increase in CD4+T cell-specific IL-10 expression inH. pylori-infected IL-21-deficient mice. Our results indicate that IL-21 regulates Th1 and Th17 effector responses during chronicH. pyloriinfection in a STAT1- and STAT3-dependent manner, therefore playing a major role controllingH. pyloriinfection and gastritis.IMPORTANCEHelicobacter pyloriis the dominant member of the gastric microbiota in more than 50% of the world’s population.H. pyloricolonization has been implicated in gastritis and gastric cancer, as infection withH. pyloriis the single most common risk factor for gastric cancer. Current data suggest that, in addition to bacterial virulence factors, the magnitude and types of immune responses influence the outcome of colonization and chronic infection. This study uses a combined computational and experimental approach to investigate how IL-21, a proinflammatory T cell-derived cytokine, maintains the chronic proinflammatory T cell immune response driving chronic gastritis duringH. pyloriinfection. This research will also provide insight into a myriad of other infectious and immune disorders in which IL-21 is increasingly recognized to play a central role. The use of IL-21-related therapies may provide treatment options for individuals chronically colonized withH. pylorias an alternative to aggressive antibiotics.

Sign in / Sign up

Export Citation Format

Share Document