scholarly journals Contribution of Asparagine Catabolism to Salmonella Virulence

2016 ◽  
Vol 85 (2) ◽  
Author(s):  
Patrick A. McLaughlin ◽  
Michael McClelland ◽  
Hee-Jeong Yang ◽  
Steffen Porwollik ◽  
Lydia Bogomolnaya ◽  
...  
Keyword(s):  
T Cell ◽  
Pathogenic Bacteria ◽  
Protein A ◽  
Metabolic Reprogramming ◽  
Wild Type ◽  
Content Type ◽  
Cell Responses ◽  
Serovar Typhimurium ◽  
Salmonella Virulence ◽  
And Function

ABSTRACT Salmonellae are pathogenic bacteria that cause significant morbidity and mortality in humans worldwide. Salmonellae establish infection and avoid clearance by the immune system by mechanisms that are not well understood. We previously showed that l-asparaginase II produced by Salmonella enterica serovar Typhimurium (S. Typhimurium) inhibits T cell responses and mediates virulence. In addition, we previously showed that asparagine deprivation such as that mediated by l-asparaginase II of S. Typhimurium causes suppression of activation-induced T cell metabolic reprogramming. Here, we report that STM3997, which encodes a homolog of disulfide bond protein A (dsbA) of Escherichia coli, is required for l-asparaginase II stability and function. Furthermore, we report that l-asparaginase II localizes primarily to the periplasm and acts together with l-asparaginase I to provide S. Typhimurium the ability to catabolize asparagine and assimilate nitrogen. Importantly, we determined that, in a murine model of infection, S. Typhimurium lacking both l-asparaginase I and II genes competes poorly with wild-type S. Typhimurium for colonization of target tissues. Collectively, these results indicate that asparagine catabolism contributes to S. Typhimurium virulence, providing new insights into the competition for nutrients at the host-pathogen interface.

scholarly journals Timing of Toll-Like Receptor 9 Agonist Administration in Pneumococcal Vaccination Impacts Both Humoral and Cellular Immune Responses as Well as Nasopharyngeal Colonization in Mice

2012 ◽  
Vol 80 (5) ◽  
pp. 1744-1752 ◽  
Author(s):  
Katrine M. Jensen ◽  
Jesper Melchjorsen ◽  
Frederik Dagnaes-Hansen ◽  
Uffe B. S. Sørensen ◽  
Rune R. Laursen ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
Conjugate Vaccine ◽  
Interleukin 2 ◽  
T Cell Responses ◽  
Simultaneous Administration ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Content Type ◽  
Cell Responses

ABSTRACTSynthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs, CpG ODN, are Toll-like receptor 9 agonists (TLR9a), which have been used as adjuvants in pneumococcal vaccines to improve antibody responses in immunodeficient patients. Here, we examined whether the coadministration of TLR9a with pneumococcal CRM197-conjugate vaccine enhances protection against pneumococcal colonization, the levels of antipolysaccharide antibodies, and the CD4+T-cell responses. Wild-type BALB/c mice and B-cell-deficient BALB/c Igh-Jtm1Dhumice were immunized twice with the following: (i) PCV alone; (ii) simultaneous PCV and TLR9a; (iii) PCV and then TLR9a, after a 48-h delay; (iv) TLR9a alone; and (v) phosphate-buffered saline. Nasopharyngeal protection, serum antibodies, CD4+T-cell responses, and clearance of bacteremia after intraperitoneal challenge withStreptococcus pneumoniae6B were evaluated. We found decreased nasopharyngeal protection againstS. pneumoniae6B colonization after simultaneous immunization with PCV and TLR9a compared to immunization with PCV alone in wild-type BALB/c mice (P= 0.037). A similar trend was observed in B-cell-deficient BALB/c Igh-Jtm1Dhumice. Simultaneous administration did not enhance antibody levels and lowered the CRM197-specific cytokine release of gamma interferon, interleukin-2 (IL-2), IL-5 and IL-13. Immunization with PCV and then TLR9a, after a 48-h delay, significantly improved nasopharyngeal protection compared to simultaneous administration (P= 0.011). Furthermore, delaying TLR9a delivery increased antibody titers compared to both simultaneous administration (P= 0.001) and PCV immunization alone (P= 0.026). In conclusion, the immunological and clinical impact of adjuvanting a pneumococcal conjugate vaccine (Prevnar; Pfizer) with a TLR9a is highly depended on timing of the adjuvant administration. Thus, careful timing of adjuvant administration may improve novel vaccine formulations.

scholarly journals The Subcellular Location of Ovalbumin in Plasmodium berghei Blood Stages Influences the Magnitude of T-Cell Responses

2014 ◽  
Vol 82 (11) ◽  
pp. 4654-4665 ◽  
Author(s):  
Jing-Wen Lin ◽  
Tovah N. Shaw ◽  
Takeshi Annoura ◽  
Aurélie Fougère ◽  
Pascale Bouchier ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Plasmodium Berghei ◽  
Parasitophorous Vacuole ◽  
T Cell Responses ◽  
Subcellular Location ◽  
Expression Level ◽  
Content Type ◽  
Cell Responses ◽  
And Function

ABSTRACTModel antigens are frequently introduced into pathogens to study determinants that influence T-cell responses to infections. To address whether an antigen's subcellular location influences the nature and magnitude of antigen-specific T-cell responses, we generatedPlasmodium bergheiparasites expressing the model antigen ovalbumin (OVA) either in the parasite cytoplasm or on the parasitophorous vacuole membrane (PVM). For cytosolic expression, OVA alone or conjugated to mCherry was expressed from a strong constitutive promoter (OVAhsp70orOVA::mCherryhsp70); for PVM expression, OVA was fused to HEP17/EXP1 (OVA::Hep17hep17). Unexpectedly, OVA expression inOVAhsp70parasites was very low, but when OVA was fused to mCherry (OVA::mCherryhsp70), it was highly expressed. OVA expression inOVA::Hep17hep17parasites was strong but significantly less than that inOVA::mCherryhsp70parasites. These transgenic parasites were used to examine the effects of antigen subcellular location and expression level on the development of T-cell responses during blood-stage infections. While all OVA-expressing parasites induced activation and proliferation of OVA-specific CD8+T cells (OT-I) and CD4+T cells (OT-II), the level of activation varied:OVA::Hep17hep17parasites induced significantly stronger splenic and intracerebral OT-I and OT-II responses than those ofOVA::mCherryhsp70parasites, butOVA::mCherryhsp70parasites promoted stronger OT-I and OT-II responses than those ofOVAhsp70parasites. Despite lower OVA expression levels,OVA::Hep17hep17parasites induced stronger T-cell responses than those ofOVA::mCherryhsp70parasites. These results indicate that unconjugated cytosolic OVA is not stably expressed inPlasmodiumparasites and, importantly, that its cellular location and expression level influence both the induction and magnitude of parasite-specific T-cell responses. These parasites represent useful tools for studying the development and function of antigen-specific T-cell responses during malaria infection.

scholarly journals CD4 T Cell Antigens from Staphylococcus aureus Newman Strain Identified following Immunization with Heat-Killed Bacteria

2012 ◽  
Vol 19 (4) ◽  
pp. 477-489 ◽  
Author(s):  
Paulraj K. Lawrence ◽  
Bachra Rokbi ◽  
Nadège Arnaud-Barbe ◽  
Eric L. Sutten ◽  
Junzo Norimine ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
T Cell ◽  
Reverse Genetics ◽  
Vaccine Development ◽  
Protein A ◽  
Cd4 T Cell ◽  
Content Type ◽  
Intramammary Infections ◽  
T Cell Antigens ◽  
Ifn Γ

ABSTRACTStaphylococcus aureusis a commensal bacterium associated with the skin and mucosal surfaces of humans and animals that can also cause chronic infection. The emergence of antibiotic-resistant strains such as methicillin-resistantS. aureus(MRSA) and strains causing chronic intramammary infections (IMI) in cows results in severe human and livestock infections. Conventional approaches to vaccine development have yielded only a few noneffective vaccines against MRSA or IMI strains, so there is a need for improved vaccine development. CD4 T lymphocytes are required for promoting gamma interferon (IFN-γ) mediated immunoglobulin isotype switching in B lymphocytes to produce high-affinity IgG antibodies and IFN-γ-mediated phagocyte activation for an effective resolution of bacterial infection. However, the lack of known CD4 T cell antigens fromS. aureushas made it difficult to design effective vaccines. The goal of this study was to identifyS. aureusproteins recognized by immune CD4 T cells. Using a reverse genetics approach, 43 antigens were selected from theS. aureusNewman strain. These included lipoproteins, proteases, transcription regulators, an alkaline shock protein, conserved-domain proteins, hemolysins, fibrinogen-binding protein, staphylokinase, exotoxin, enterotoxin, sortase, and protein A. Screening of expressed proteins for recall T cell responses in outbred, immune calves identified 13 proteins that share over 80% sequence identity among MRSA or IMI strains. These may be useful for inclusion in a broadly protective multiantigen vaccine against MRSA or IMI.

scholarly journals Peripheral T-Cell Reactivity to Heat Shock Protein 70 and Its Cofactor GrpE from Tropheryma whipplei Is Reduced in Patients with Classical Whipple's Disease

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Lucia Trotta ◽  
Kathleen Weigt ◽  
Katina Schinnerling ◽  
Anika Geelhaar-Karsch ◽  
Gerrit Oelkers ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Protein 70 ◽  
T Cell Responses ◽  
Tropheryma Whipplei ◽  
Content Type ◽  
Cell Responses ◽  
Ifn Γ

ABSTRACT Classical Whipple's disease (CWD) is characterized by the lack of specific Th1 response toward Tropheryma whipplei in genetically predisposed individuals. The cofactor GrpE of heat shock protein 70 (Hsp70) from T. whipplei was previously identified as a B-cell antigen. We tested the capacity of Hsp70 and GrpE to elicit specific proinflammatory T-cell responses. Peripheral mononuclear cells from CWD patients and healthy donors were stimulated with T. whipplei lysate or recombinant GrpE or Hsp70 before levels of CD40L, CD69, perforin, granzyme B, CD107a, and gamma interferon (IFN-γ) were determined in T cells by flow cytometry. Upon stimulation with total bacterial lysate or recombinant GrpE or Hsp70 of T. whipplei, the proportions of activated effector CD4+ T cells, determined as CD40L+ IFN-γ+, were significantly lower in patients with CWD than in healthy controls; CD8+ T cells of untreated CWD patients revealed an enhanced activation toward unspecific stimulation and T. whipplei-specific degranulation, although CD69+ IFN-γ+ CD8+ T cells were reduced upon stimulation with T. whipplei lysate and recombinant T. whipplei-derived proteins. Hsp70 and its cofactor GrpE are immunogenic in healthy individuals, eliciting effective responses against T. whipplei to control bacterial spreading. The lack of specific T-cell responses against these T. whipplei-derived proteins may contribute to the pathogenesis of CWD.

scholarly journals Long-Term Immunity to Trypanosoma cruzi in the Absence of Immunodominanttrans-Sialidase-Specific CD8+T Cells

2016 ◽  
Vol 84 (9) ◽  
pp. 2627-2638 ◽  
Author(s):  
Charles S. Rosenberg ◽  
Weibo Zhang ◽  
Juan M. Bustamante ◽  
Rick L. Tarleton
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transgenic Mice ◽  
Trypanosoma Cruzi ◽  
T Cell Responses ◽  
Content Type ◽  
Cell Responses ◽  
Pathogen Control ◽  
Immunodominant Epitopes

Trypanosoma cruziinfection drives the expansion of remarkably focused CD8+T cell responses targeting epitopes encoded by varianttrans-sialidase (TS) genes. Infection of C57BL/6 mice withT. cruziresults in up to 40% of all CD8+T cells committed to recognition of the dominant TSKB20 and subdominant TSKB18 TS epitopes. However, despite this enormous response, these mice fail to clearT. cruziinfection and subsequently develop chronic disease. One possible reason for the failure to cureT. cruziinfection is that immunodomination by these TS-specific T cells may interfere with alternative CD8+T cell responses more capable of complete parasite elimination. To address this possibility, we created transgenic mice that are centrally tolerant to these immunodominant epitopes. Mice expressing TSKB20, TSKB18, or both epitopes controlledT. cruziinfection and developed effector CD8+T cells that maintained an activated phenotype. Memory CD8+T cells from drug-cured TSKB-transgenic mice rapidly responded to secondaryT. cruziinfection. In the absence of the response to TSKB20 and TSKB18, immunodominance did not shift to other known subdominant epitopes despite the capacity of these mice to expand epitope-specific T cells specific for the model antigen ovalbumin expressed by engineered parasites. Thus, CD8+T cell responses tightly and robustly focused on a few epitopes within variant TS antigens appear to neither contribute to, nor detract from, the ability to controlT. cruziinfection. These data also indicate that the relative position of an epitope within a CD8+immunodominance hierarchy does not predict its importance in pathogen control.

scholarly journals Extensive Polymorphism and Evidence of Immune Selection in a Highly Dominant Antigen Recognized by Bovine CD8 T Cells Specific for Theileria annulata

2011 ◽  
Vol 79 (5) ◽  
pp. 2059-2069 ◽  
Author(s):  
Niall D. MacHugh ◽  
William Weir ◽  
Alison Burrells ◽  
Regina Lizundia ◽  
Simon P. Graham ◽  
...  
Keyword(s):  
Amino Acid ◽  
T Cell ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Theileria Annulata ◽  
T Cell Epitopes ◽  
Major Histocompatibility Complex Haplotype ◽  
Content Type ◽  
Cell Responses ◽  
Restricted Epitope

ABSTRACTAlthough parasite strain-restricted CD8 T cell responses have been described for several protozoa, the precise role of antigenic variability in immunity is poorly understood. The tick-borne protozoan parasiteTheileria annulatainfects leukocytes and causes an acute, often fatal lymphoproliferative disease in cattle. Building on previous evidence of strain-restricted CD8 T cell responses toT. annulata, this study set out to identify and characterize the variability of the target antigens. Three antigens were identified by screening expressed parasite cDNAs with specific CD8 T cell lines. In cattle expressing the A10 class I major histocompatibility complex haplotype, A10-restricted CD8 T cell responses were shown to be focused entirely on a single dominant epitope in one of these antigens (Ta9). Sequencing of the Ta9 gene from field isolates ofT. annulatademonstrated extensive sequence divergence, resulting in amino acid polymorphism within the A10-restricted epitope and a second A14-restricted epitope. Statistical analysis of the allelic sequences revealed evidence of positive selection for amino acid substitutions within the region encoding the CD8 T cell epitopes. Sequence differences in the A10-restricted epitope were shown to result in differential recognition by individual CD8 T cell clones, while clones also differed in their ability to recognize different alleles. Moreover, the representation of these clonal specificities within the responding CD8 T cell populations differed between animals. As well as providing an explanation for incomplete protection observed after heterologous parasite challenge of vaccinated cattle, these results have important implications for the choice of antigens for the development of novel subunit vaccines.

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.

scholarly journals Dynamic structural cell responses in the thymus to acute injury, regeneration, and age

2021 ◽  
Author(s):  
Lorenz L Jahn ◽  
Anastasia I Kousa ◽  
Lisa Sikkema ◽  
Angel E Flores ◽  
Kimon V Argyropoulos ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Marrow Transplant ◽  
Cell Development ◽  
Acute Injury ◽  
Thymic Function ◽  
Structural Cell ◽  
Cell Responses ◽  
And Function ◽  
Old Mice

The thymus, the primary site of T cell development, is extremely sensitive to insult but also harbors tremendous capacity for repair. Using single cell sequencing of thymic structural cells, as well as functional and structural analyses, we revealed distinct regenerative programs by endothelial and mesenchymal subsets after injury that stimulated epithelial repair; the compartment primarily supporting T cell development. Thymic function not only declined over lifespan, contributing to immune aging, but the capacity of the thymus to regenerate after damage also declined in old mice. This could be attributed to an inability of the old microenvironment to induce reparative programs; leading to reduced ability to restore tissue structure and function. These findings provide a detailed framework for the response of structural cells to aging and acute damage, which could have considerable implications for our understanding of aging immunity and recovery from treatments such as chemotherapy and bone marrow transplant.

scholarly journals TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum

2021 ◽  
Vol 15 (11) ◽  
pp. e0009943
Author(s):  
Haixia Wei ◽  
Hongyan Xie ◽  
Jiale Qu ◽  
Anqi Xie ◽  
Shihao Xie ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Gene Knockout ◽  
Innate Immune ◽  
Wild Type ◽  
Cell Responses ◽  
Splenic Cells ◽  
And Function ◽  
Egg Antigen

B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5–6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.

scholarly journals Curcumin Reduces the Motility of Salmonella enterica Serovar Typhimurium by Binding to the Flagella, Thereby Leading to Flagellar Fragility and Shedding

2016 ◽  
Vol 198 (13) ◽  
pp. 1798-1811 ◽  
Author(s):  
Sandhya Amol Marathe ◽  
Arjun Balakrishnan ◽  
Vidya Devi Negi ◽  
Deepika Sakorey ◽  
Nagasuma Chandra ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Binding Assay ◽  
Protein A ◽  
Intestinal Barrier ◽  
Site Directed Mutagenesis ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Flagellar Filament ◽  
Fluorescence Binding ◽  
Fluorescence Binding Assay

ABSTRACTOne of the important virulence properties of the pathogen is its ability to travel to a favorable environment, cross the viscous mucus barrier (intestinal barrier for enteric pathogens), and reach the epithelia to initiate pathogenesis with the help of an appendage, like flagella. Nonetheless, flagella can act as an “Achilles heel,” revealing the pathogen's presence to the host through the stimulation of innate and adaptive immune responses. We assessed whether curcumin, a dietary polyphenol, could alter the motility ofSalmonella, a foodborne pathogen. It reduced the motility ofSalmonella entericaserovar Typhimurium by shortening the length of the flagellar filament (from ∼8 μm to ∼5 μm) and decreasing its density (4 or 5 flagella/bacterium instead of 8 or 9 flagella/bacterium). Upon curcumin treatment, the percentage of flagellated bacteria declined from ∼84% to 59%. However, no change was detected in the expression of the flagellin gene and protein. A fluorescence binding assay demonstrated binding of curcumin to the flagellar filament. This might make the filament fragile, breaking it into smaller fragments. Computational analysis predicted the binding of curcumin, its analogues, and its degraded products to a flagellin molecule at an interface between domains D1 and D2. Site-directed mutagenesis and a fluorescence binding assay confirmed the binding of curcumin to flagellin at residues ASN120, ASP123, ASN163, SER164, ASN173, and GLN175.IMPORTANCEThis work, to our knowledge the first report of its kind, examines how curcumin targets flagellar density and affects the pathogenesis of bacteria. We found that curcumin does not affect any of the flagellar synthesis genes. Instead, it binds to the flagellum and makes it fragile. It increases the torsional stress on the flagellar filament that then breaks, leaving fewer flagella around the bacteria. Flagella, which are crucial ligands for Toll-like receptor 5, are some of the most important appendages ofSalmonella. Curcumin is an important component of turmeric, which is a major spice used in Asian cooking. The loss of flagella can, in turn, change the pathogenesis of bacteria, making them more robust and fit in the host.

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