scholarly journals Inhibition of Indoleamine 2,3-Dioxygenase Activity by Levo-1-Methyl Tryptophan Blocks Gamma Interferon-Induced Chlamydia trachomatis Persistence in Human Epithelial Cells

2011 ◽  
Vol 79 (11) ◽  
pp. 4425-4437 ◽  
Author(s):  
Joyce A. Ibana ◽  
Robert J. Belland ◽  
Arnold H. Zea ◽  
Danny J. Schust ◽  
Takeshi Nagamatsu ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Epithelial Cells ◽  
Gamma Interferon ◽  
Developmental Cycle ◽  
Tryptophan Depletion ◽  
Content Type ◽  
Indoleamine 2,3 Dioxygenase ◽  
Human Epithelial Cells ◽  
Ifn Γ

ABSTRACTGamma interferon (IFN-γ) induces expression of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO1) in human epithelial cells, the permissive cells for the obligate intracellular bacteriumChlamydia trachomatis. IDO1 depletes tryptophan by catabolizing it to kynurenine with consequences forC. trachomatis, which is a tryptophan auxotroph.In vitrostudies reveal that tryptophan depletion can result in the formation of persistent (viable but noncultivable) chlamydial forms. Here, we tested the effects of the IDO1 inhibitor, levo-1-methyl-tryptophan (L-1MT), on IFN-γ-inducedC. trachomatispersistence. We found that addition of 0.2 mM L-1MT to IFN-γ-exposed infected HeLa cell cultures restricted IDO1 activity at the mid-stage (20 h postinfection [hpi]) of the chlamydial developmental cycle. This delayed tryptophan depletion until the late stage (38 hpi) of the cycle. Parallel morphological and gene expression studies indicated a consequence of the delay was a block in the induction ofC. trachomatispersistence by IFN-γ. Furthermore, L-1MT addition allowedC. trachomatisto undergo secondary differentiation, albeit with limited productive multiplication of the bacterium. IFN-γ-induced persistent infections in epithelial cells have been previously reported to be more resistant to doxycycline than normal productive infectionsin vitro. Pertinent to this observation, we found that L-1MT significantly improved the efficacy of doxycycline in clearing persistentC. trachomatisforms. It has been postulated that persistent forms ofC. trachomatismay contribute to chronic chlamydial disease. Our findings suggest that IDO1 inhibitors such as L-1MT might provide a novel means to investigate, and potentially target, persistent chlamydial forms, particularly in conjunction with conventional therapeutics.

scholarly journals Differential Effects of Gamma Interferon on Chlamydia trachomatis Growth in Polarized and Nonpolarized Human Epithelial Cells in Culture

1998 ◽  
Vol 66 (5) ◽  
pp. 2349-2351 ◽  
Author(s):  
Colleen D. Kane ◽  
Gerald I. Byrne
Keyword(s):  
Chlamydia Trachomatis ◽  
Epithelial Cells ◽  
Gamma Interferon ◽  
Growth Modulation ◽  
Differential Effects ◽  
Cells In Culture ◽  
Human Epithelial Cells ◽  
Polarized Cells ◽  
Ifn Γ

ABSTRACT The effects of gamma interferon (IFN-γ) on Chlamydia trachomatis growth in polarized epithelial cells were examined. The range of IFN-γ concentrations causing aberrant chlamydial growth was wider in polarized than in nonpolarized cultures. Results indicate that chlamydial growth modulation in polarized cells readily leads to persistence and better reflects in vivo conditions.

scholarly journals Characterization of theIn VitroChlamydia pecorumResponse to Gamma Interferon

2018 ◽  
Vol 86 (4) ◽  
Author(s):  
M. Mominul Islam ◽  
Martina Jelocnik ◽  
Wilhelmina M. Huston ◽  
Peter Timms ◽  
Adam Polkinghorne
Keyword(s):  
Immune Response ◽  
Epithelial Cells ◽  
Host Cell ◽  
Anthranilic Acid ◽  
Gamma Interferon ◽  
Tryptophan Depletion ◽  
Content Type ◽  
Natural Hosts ◽  
Ifn Γ

ABSTRACTChlamydia pecorumis an important intracellular bacterium that causes a range of diseases in animals, including a native Australian marsupial, the koala. In humans and animals, a gamma interferon (IFN-γ)-mediated immune response is important for the control of intracellular bacteria. The present study tested the hypotheses thatC. pecorumcan escape IFN-γ-mediated depletion of host cell tryptophan pools. In doing so, we demonstrated that, unlikeChlamydia trachomatis,C. pecorumis completely resistant to IFN-γ in human epithelial cells. While the growth ofC. pecorumwas inhibited in tryptophan-deficient medium, it could be restored by the addition of kynurenine, anthranilic acid, and indole, metabolites that could be exploited by the gene products of theC. pecorumtryptophan biosynthesis operon. We also found that expression oftrpgenes was detectable only whenC. pecorumwas grown in tryptophan-free medium, with gene repression occurring in response to the addition of kynurenine, anthranilic acid, and indole. When grown in bovine kidney epithelial cells, bovine IFN-γ also failed to restrict the growth ofC. pecorum, whileC. trachomatiswas inhibited, suggesting thatC. pecorumcould use the same mechanisms to evade the immune responsein vivoin its natural host. Highlighting the different mechanisms triggered by IFN-γ, however, both species failed to grow in murine McCoy cells treated with murine IFN-γ. This work confirms previous hypotheses about the potential survival ofC. pecorumafter IFN-γ-mediated host cell tryptophan depletion and raises questions about the immune pathways used by the natural hosts ofC. pecorumto control the widespread pathogen.

scholarly journals Chlamydia trachomatisIs Resistant to Inclusion Ubiquitination and Associated Host Defense in Gamma Interferon-Primed Human Epithelial Cells

mBio ◽  
2016 ◽  
Vol 7 (6) ◽  
Author(s):  
Arun K. Haldar ◽  
Anthony S. Piro ◽  
Ryan Finethy ◽  
Scott T. Espenschied ◽  
Hannah E. Brown ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Epithelial Cells ◽  
Binding Protein ◽  
Gamma Interferon ◽  
Human Cells ◽  
Antimicrobial Protein ◽  
Human Host ◽  
Human Epithelial Cells ◽  
Resistance Pathway ◽  
Ifn Γ

ABSTRACTThe cytokine gamma interferon (IFN-γ) induces cell-autonomous immunity to combat infections with intracellular pathogens, such as the bacteriumChlamydia trachomatis. The present study demonstrates that IFN-γ-primed human cells ubiquitinate and eliminate intracellularChlamydia-containing vacuoles, so-called inclusions. We previously described how IFN-γ-inducible immunity-related GTPases (IRGs) employ ubiquitin systems to mark inclusions for destruction in mouse cells and, furthermore, showed that the rodent pathogenChlamydia muridarumblocks ubiquitination of its inclusions by interfering with mouse IRG function. Here, we report that ubiquitination of inclusions in human cells is independent of IRG and thus distinct from the murine pathway. We show thatC. muridarumis susceptible to inclusion ubiquitination in human cells, while the closely related human pathogenC. trachomatisis resistant.C. muridarum, but notC. trachomatis, inclusions attract several markers of cell-autonomous immunity, including the ubiquitin-binding protein p62, the ubiquitin-like protein LC3, and guanylate-binding protein 1. Consequently, we find that IFN-γ priming of human epithelial cells triggers the elimination ofC. muridarum, but notC. trachomatis, inclusions. This newly described defense pathway is independent of indole-2,3-dioxygenase, a known IFN-γ-inducible anti-Chlamydiaresistance factor. Collectively, our observations indicate thatC. trachomatisevolved mechanisms to avoid a human-specific, ubiquitin-mediated response as part of its unique adaptation to its human host.IMPORTANCEChlamydia trachomatisis the leading cause of sexually transmitted bacterial infections and responsible for significant morbidity, including pelvic inflammatory disease, infertility, and ectopic pregnancies in women. As an obligate intracellular pathogen,C. trachomatisis in perpetual conflict with cell-intrinsic defense programs executed by its human host. Our study defines a novel anti-Chlamydiahost resistance pathway active in human epithelial cells. This defense program promotes the deposition of the small antimicrobial protein ubiquitin on vacuoles containingChlamydia. We show that this ubiquitin-based resistance pathway of human cells is highly effective against aChlamydiaspecies adapted to rodents but ineffective against human-adaptedC. trachomatis. This observation indicates thatC. trachomatisevolved strategies to avoid entrapment within ubiquitin-labeled vacuoles as part of its adaptation to the human innate immune system.

scholarly journals Gamma Interferon Is Required for Chlamydia Clearance but Is Dispensable for T Cell Homing to the Genital Tract

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Jennifer D. Helble ◽  
Rodrigo J. Gonzalez ◽  
Ulrich H. von Andrian ◽  
Michael N. Starnbach
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Chlamydia Trachomatis ◽  
Genital Tract ◽  
Gamma Interferon ◽  
Cell Homing ◽  
Content Type ◽  
T Cell Homing ◽  
Ifn Γ

ABSTRACT While there is no effective vaccine against Chlamydia trachomatis infection, previous work has demonstrated the importance of C. trachomatis-specific CD4+ T cells (NR1 T cells) in pathogen clearance. Specifically, NR1 T cells have been shown to be protective in mice, and this protection depends on the host’s ability to sense the cytokine gamma interferon (IFN-γ). However, it is unclear what role NR1 production or sensing of IFN-γ plays in T cell homing to the genital tract or T cell-mediated protection against C. trachomatis. Using two-photon microscopy and flow cytometry, we found that naive wild-type (WT), IFN-γ−/−, and IFN-γR−/− NR1 T cells specifically home to sections in the genital tract that contain C. trachomatis. We also determined that protection against infection requires production of IFN-γ from either NR1 T cells or endogenous cells, further highlighting the importance of IFN-γ in clearing C. trachomatis infection. IMPORTANCE Chlamydia trachomatis is an important mucosal pathogen that is the leading cause of sexually transmitted bacterial infections in the United States. Despite this, there is no vaccine currently available. In order to develop such a vaccine, it is necessary to understand the components of the immune response that can lead to protection against this pathogen. It is well known that antigen-specific CD4+ T cells are critical for Chlamydia clearance, but the contexts in which they are protective or not protective are unknown. Here, we aimed to characterize the importance of gamma interferon production and sensing by T cells and the effects on the immune response to C. trachomatis. Our work here helps to define the contexts in which antigen-specific T cells can be protective, which is critical to our ability to design an effective and protective vaccine against C. trachomatis.

scholarly journals Bactericidal Activity of First-Choice Antibiotics against Gamma Interferon-Induced Persistent Infection of Human Epithelial Cells by Chlamydia trachomatis

2005 ◽  
Vol 49 (5) ◽  
pp. 1787-1793 ◽  
Author(s):  
Nathalie Reveneau ◽  
Deborah D. Crane ◽  
Elizabeth Fischer ◽  
Harlan D. Caldwell
Keyword(s):  
Chlamydia Trachomatis ◽  
Epithelial Cells ◽  
Persistent Infection ◽  
Inflammatory Diseases ◽  
Acute Infection ◽  
Gamma Interferon ◽  
Minimal Bactericidal Concentration ◽  
Chronic Inflammatory Diseases ◽  
First Choice ◽  
Ifn Γ

ABSTRACT Chlamydia trachomatis is responsible for clinically important chronic inflammatory diseases of humans, including trachoma and pelvic inflammatory disease. Persistent infection of mucosal sites may contribute to the development of these chronic inflammatory diseases. Standard clinical therapy results in satisfactory cure rates of acute infections; however, chronic infection associated with persistence has been suggested to be less responsive to antibiotic therapy. We report the efficiency of two first-line chlamydial antibiotics, azithromycin and doxycycline, under conditions of eradication of C. trachomatis persistent infection using the in vitro model of gamma interferon (IFN-γ)-mediated persistence and reactivation from persistence. Doxycycline was superior in eradicating acute (minimal bactericidal concentration [MBC]100 = 2.5 to 5.0 μg/ml) compared to persistent (MBC100 = 10 to 50 μg/ml) infection. In contrast, azithromycin was significantly more effective in eradicating persistent infection (MBC100 = 2.5 to 5.0 μg/ml) than acute infection (MBC100 = 10 to 50 μg/ml). The superior bactericidal effect of azithromycin against persistent infection was found to correlate with the enhanced uptake of the drug by IFN-γ-treated infected epithelial cells. Based on these findings, we hypothesize that azithromycin should be a particularly efficacious anti-infective agent for the eradication of IFN-γ-induced chlamydial persistent infection in vivo.

scholarly journals Transcriptional Profiling of Human Epithelial Cells Infected with Plasmid-Bearing and Plasmid-Deficient Chlamydia trachomatis

2014 ◽  
Vol 83 (2) ◽  
pp. 534-543 ◽  
Author(s):  
Stephen F. Porcella ◽  
John H. Carlson ◽  
Daniel E. Sturdevant ◽  
Gail L. Sturdevant ◽  
Kishore Kanakabandi ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Epithelial Cells ◽  
Transcriptional Profiling ◽  
Colony Stimulating Factor ◽  
Content Type ◽  
Human Epithelial Cells ◽  
Infected Cells ◽  
Macrophage Colony Stimulating Factor ◽  
Macrophage Colony ◽  
Stimulating Factor

Chlamydia trachomatisis an obligate intracellular epitheliotropic bacterial pathogen of humans. Infection of the eye can result in trachoma, the leading cause of preventable blindness in the world. The pathophysiology of blinding trachoma is driven by multiple episodes of reinfection of conjunctival epithelial cells, producing an intense chronic inflammatory response resulting in submucosal tissue remodeling and scarring. Recent reports have shown that infection with trachoma organisms lacking the cryptic chlamydial plasmid is highly attenuated in macaque eyes, a relevant experimental model of human trachoma infection. To better understand the molecular basis of plasmid-mediated infection attenuation and the potential modulation of host immunity, we conducted transcriptional profiling of human epithelial cells infected withC. trachomatisplasmid-bearing (A2497) and plasmid-deficient (A2497P−) organisms. Infection of human epithelial cells with either strain increased the expression of host genes coding for proinflammatory (granulocyte-macrophage colony-stimulating factor [GM-CSF], macrophage colony-stimulating factor [MCSF], interleukin-6 [IL-6], IL-8, IL-1α, CXCL1, CXCL2, CXCL3, intercellular adhesion molecule 1 [ICAM1]), chemoattraction (CCL20, CCL5, CXCL10), immune suppression (PD-L1, NFKB1B, TNFAIP3, CGB), apoptosis (CASP9, FAS, IL-24), and cell growth and fibrosis (EGR1 and IL-20) proteins. Statistically significant increases in the levels of expression of many of these genes were found in A2497-infected cells compared to the levels of expression in A2497P−-infected cells. Our findings suggest that the chlamydial plasmid plays a focal role in the host cell inflammatory response to infection and immune avoidance. These results provide new insights into the role of the chlamydial plasmid as a chlamydial virulence factor and its contributions to trachoma pathogenesis.

scholarly journals Incubation of Whole Blood at 39°C Augments Gamma Interferon (IFN-γ)-Induced Protein 10 and IFN-γ Responses to Mycobacterium tuberculosis Antigens

2011 ◽  
Vol 18 (7) ◽  
pp. 1150-1156 ◽  
Author(s):  
Martine G. Aabye ◽  
Pernille Ravn ◽  
Isik S. Johansen ◽  
Jesper Eugen-Olsen ◽  
Morten Ruhwald
Keyword(s):  
Mycobacterium Tuberculosis ◽  
T Cell ◽  
Whole Blood ◽  
Incubation Temperature ◽  
Gamma Interferon ◽  
Content Type ◽  
Interleukin 7 ◽  
Ifn Γ

ABSTRACTA rarely challenged dogma in cell-mediated immune (CMI) assays is the incubation temperature, 37°C. Fever augments proinflammatory immune responsesin vivo, and the aim of this study was to explore whether incubation at fever-range temperature could increase antigen-specific biomarker responses. We compared CMI responses following incubation of whole blood at 37°C and 39°C. Whole blood was obtained from (i) 34 healthy subjects whose blood was incubated with TB10.4 antigen, present in theMycobacterium bovisbacillus Calmette-Guérin vaccine and many environmental mycobacteria; (ii) 8 TB patients and 8 controls incubated withMycobacterium tuberculosis-specific antigens in the QuantiFERON-TB Gold test (QFT-IT); and (iii) from both groups incubated with a T cell mitogen. T cell responses (gamma interferon [IFN-γ]) and responses from antigen-presenting cells (IFN-γ-induced protein 10 [IP-10]) were determined. We further evaluated the effect of adding interleukin-7 (IL-7) and blocking IL-10 during incubation. In TB patients, IFN-γ and IP-10 levels were increased 4.1- and 3.4-fold, respectively, at 39°C incubation (P< 0.001). Similar results were seen after mitogen stimulation. In subjects responding to TB10.4, the effects were less pronounced and significant only for IP-10. Incubation at 39°C increased IP-10 and IFN-γ responsiveness to both antigens and mitogen in persons with baseline or initial low responses. Adding IL-7 and blocking IL-10 augmented the effects in synergy with fever-range temperature. Incubation at fever-range temperature vividly increases CMI responsiveness to antigen stimulationin vitroin tuberculosis patients and may increase the sensitivity of CMI assays.

scholarly journals Nitric Oxide-Mediated Regulation of Gamma Interferon-Induced Bacteriostasis: Inhibition and Degradation of Human Indoleamine 2,3-Dioxygenase

2004 ◽  
Vol 72 (5) ◽  
pp. 2723-2730 ◽  
Author(s):  
Christian Hucke ◽  
Colin R. MacKenzie ◽  
Koku D. Z. Adjogble ◽  
Osamu Takikawa ◽  
Walter Däubener
Keyword(s):  
Nitric Oxide ◽  
Gene Transcription ◽  
Kynurenine Pathway ◽  
Gamma Interferon ◽  
Human Cells ◽  
Epithelial Cell Line ◽  
Tryptophan Depletion ◽  
No Production ◽  
Indoleamine 2,3 Dioxygenase ◽  
Ifn Γ

ABSTRACT Tryptophan depletion resulting from indoleamine 2,3-dioxygenase (IDO) activity within the kynurenine pathway is one of the most prominent gamma interferon (IFN-γ)-inducible antimicrobial effector mechanisms in human cells. On the other hand, nitric oxide (NO) produced by the inducible isoform of NO synthase (iNOS) serves a more immunoregulatory role in human cells and thereby interacts with tryptophan depletion in a number of ways. We investigated the effects of NO on IDO gene transcription, protein synthesis, and enzyme activity as well as on IDO-mediated bacteriostasis in the human epithelial cell line RT4. IFN-γ-stimulated RT4 cells were able to inhibit the growth of Staphylococcus aureus in an IDO-mediated fashion, and this bacteriostatic effect was abolished by endogenously produced NO. These findings were supported by experiments which showed that IDO activity in extracts of IFN-γ-stimulated cells is inhibited by the chemical NO donors diethylenetriamine diazeniumdiolate, S-nitroso-l-cysteine, and S-nitroso-N-acetyl-d,l-penicillamine. Furthermore, we found that both endogenous and exogenous NO strongly reduced the level of IDO protein content in RT4 cells. This effect was not due to a decrease in IDO gene transcription or mRNA stability. By using inhibitors of proteasomal proteolytic activity, we showed that NO production led to an accelerated degradation of IDO protein in the proteasome. This is the first report, to our knowledge, that demonstrates that the IDO is degraded by the proteasome and that NO has an effect on IDO protein stability.

scholarly journals Enterohemorrhagic Escherichia coli O157:H7 Shiga Toxins Inhibit Gamma Interferon-Mediated Cellular Activation

2012 ◽  
Vol 80 (7) ◽  
pp. 2307-2315 ◽  
Author(s):  
Nathan K. Ho ◽  
Juan C. Ossa ◽  
Uma Silphaduang ◽  
Roger Johnson ◽  
Kathene C. Johnson-Henry ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Tyrosine Phosphorylation ◽  
Cell Activation ◽  
Gamma Interferon ◽  
Enterohemorrhagic Escherichia Coli ◽  
Host Immune System ◽  
Content Type ◽  
Shiga Toxins ◽  
Ifn Γ

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) serotype O157:H7 is a food-borne pathogen that causes significant morbidity and mortality in developing and industrialized nations. EHEC infection of host epithelial cells is capable of inhibiting the gamma interferon (IFN-γ) proinflammatory pathway through the inhibition of Stat-1 phosphorylation, which is important for host defense against microbial pathogens. The aim of this study was to determine the bacterial factors involved in the inhibition of Stat-1 tyrosine phosphorylation. Human HEp-2 and Caco-2 epithelial cells were challenged directly with either EHEC or bacterial culture supernatants and stimulated with IFN-γ, and then the protein extracts were analyzed by immunoblotting. The data showed that IFN-γ-mediated Stat-1 tyrosine phosphorylation was inhibited by EHEC secreted proteins. Using two-dimensional difference gel electrophoresis, EHEC Shiga toxins were identified as candidate inhibitory factors. EHEC Shiga toxin mutants were then generated and complemented intrans, and mutant culture supernatant was supplemented with purified Stx to confirm their ability to subvert IFN-γ-mediated cell activation. We conclude that while other factors are likely involved in the suppression of IFN-γ-mediated Stat-1 tyrosine phosphorylation,E. coli-derived Shiga toxins represent a novel mechanism by which EHEC evades the host immune system.

scholarly journals Interleukin-18 Is Critical for Mucosa-Associated Invariant T Cell Gamma Interferon Responses toFrancisellaSpeciesIn Vitrobut NotIn Vivo

2018 ◽  
Vol 86 (5) ◽  
Author(s):  
Eric Jesteadt ◽  
Irma Zhang ◽  
Huifeng Yu ◽  
Anda Meierovics ◽  
Wei-Jen Chua Yankelevich ◽  
...  
Keyword(s):  
Pulmonary Infection ◽  
Gamma Interferon ◽  
Interleukin 18 ◽  
Class I Mhc ◽  
Content Type ◽  
Mait Cells ◽  
Ifn Γ ◽  
Mait Cell

ABSTRACTMucosa-associated invariant T (MAIT) cells are a subset of innate T cells that express a semi-invariant Vα chain paired with limited Vβ chains. MAIT cells are activated by riboflavin metabolite derivatives presented by the nonpolymorphic major histocompatibility complex class I (MHC-I)-like molecule MR1. The precise mechanisms required to activate MAIT cells are an area of intense interest. Here we used two closely related intracellular pathogens with distinct inflammasome activation phenotypes to probe the role of innate cytokines in MAIT cell activation. Using anin vitroassay containing transgenic murine MAIT cells, we show that macrophages infected withFrancisella novicida, a strong inflammasome activator, released high levels of interleukin-18 (IL-18) and stimulated high levels of MAIT cell gamma interferon (IFN-γ) through a partially MR1-independent pathway. In contrast, macrophages infected withFrancisella tularensislive vaccine strain (LVS), a weak inflammasome activator, generated little IL-18 and stimulated low MAIT cell IFN-γ through an MR1-dependent pathway. By manipulating the quantities of IL-18 in these cultures, we show that the IL-18 concentration is sufficient to influence the magnitude of MAIT cell IFN-γ production. Correspondingly, infected IL-18-deficient macrophages failed to induce substantial MAIT cell IFN-γ. In contrast, we found that MAIT cell IFN-γ production in the lungs of IL-18-deficient mice was not significantly different from that in WT mice duringF. tularensisLVS pulmonary infection. Overall, we demonstrate that while IL-18 is essential for the MAIT cell IFN-γ responsein vitro, it is not essential for MAIT cell IFN-γ production duringin vivoLVS pulmonary infection, suggesting that additional signals can drive MAIT cell IFN-γ productionin vivo.

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