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Results: 1 to 10 of 138

Publication Record


Arachidonic Acid Kills Staphylococcus aureus through a Lipid Peroxidation Mechanism.
Beavers WN, Monteith AJ, Amarnath V, Mernaugh RL, Roberts LJ, Chazin WJ, Davies SS, Skaar EP
(2019) mBio 10:
MeSH Terms: Animals, Anti-Bacterial Agents, Arachidonic Acid, Brain, Dose-Response Relationship, Drug, Drug Resistance, Bacterial, Female, Kidney, Lipid Peroxidation, Lipids, Mice, Mice, Inbred BALB C, Microbial Sensitivity Tests, Mutation, Neutrophils, Oxidative Stress, Reactive Oxygen Species, Spleen, Staphylococcal Infections, Staphylococcus aureus, Teichoic Acids
Show Abstract · Added March 11, 2020
infects every niche of the human host. In response to microbial infection, vertebrates have an arsenal of antimicrobial compounds that inhibit bacterial growth or kill bacterial cells. One class of antimicrobial compounds consists of polyunsaturated fatty acids, which are highly abundant in eukaryotes and encountered by at the host-pathogen interface. Arachidonic acid (AA) is one of the most abundant polyunsaturated fatty acids in vertebrates and is released in large amounts during the oxidative burst. Most of the released AA is converted to bioactive signaling molecules, but, independently of its role in inflammatory signaling, AA is toxic to Here, we report that AA kills through a lipid peroxidation mechanism whereby AA is oxidized to reactive electrophiles that modify macromolecules, eliciting toxicity. This process is rescued by cotreatment with antioxidants as well as in a strain genetically inactivated for (USA300 mutant) that produces lower levels of reactive oxygen species. However, resistance to AA stress in the USA300 mutant comes at a cost, making the mutant more susceptible to β-lactam antibiotics and attenuated for pathogenesis in a murine infection model compared to the parental methicillin-resistant (MRSA) strain, indicating that resistance to AA toxicity increases susceptibility to other stressors encountered during infection. This report defines the mechanism by which AA is toxic to and identifies lipid peroxidation as a pathway that can be modulated for the development of future therapeutics to treat infections. Despite the ability of the human immune system to generate a plethora of molecules to control infections, is among the pathogens with the greatest impact on human health. One class of host molecules toxic to consists of polyunsaturated fatty acids. Here, we investigated the antibacterial properties of arachidonic acid, one of the most abundant polyunsaturated fatty acids in humans, and discovered that the mechanism of toxicity against proceeds through lipid peroxidation. A better understanding of the molecular mechanisms by which the immune system kills , and by which avoids host killing, will enable the optimal design of therapeutics that complement the ability of the vertebrate immune response to eliminate infections.
Copyright © 2019 Beavers et al.
0 Communities
1 Members
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21 MeSH Terms
Defining the interaction of the protease CpaA with its type II secretion chaperone CpaB and its contribution to virulence in species.
Kinsella RL, Lopez J, Palmer LD, Salinas ND, Skaar EP, Tolia NH, Feldman MF
(2017) J Biol Chem 292: 19628-19638
MeSH Terms: Acinetobacter, Animals, Factor V, Larva, Mice, Mice, Inbred C57BL, Molecular Chaperones, Peptide Hydrolases, Protein Binding, Proteolysis, Spleen, Virulence
Show Abstract · Added March 15, 2018
, , and are a frequent cause of multidrug-resistant, healthcare-associated infections. Our previous work demonstrated that M2 possesses a functional type II secretion system (T2SS) that is required for full virulence. Further, we identified the metallo-endopeptidase CpaA, which has been shown previously to cleave human Factor V and deregulate blood coagulation, as the most abundant type II secreted effector protein. We also demonstrated that its secretion is dependent on CpaB, a membrane-bound chaperone. In this study, we show that CpaA expression and secretion are conserved across several medically relevant species. Additionally, we demonstrate that deletion of results in attenuation of M2 virulence in moth and mouse models. The virulence defects resulting from the deletion of were comparable with those observed upon abrogation of T2SS activity. The virulence defects resulting from the deletion of are comparable with those observed upon abrogation of T2SS activity. We also show that CpaA and CpaB strongly interact, forming a complex in a 1:1 ratio. Interestingly, deletion of the N-terminal transmembrane domain of CpaB results in robust secretion of CpaA and CpaB, indicating that the transmembrane domain is dispensable for CpaA secretion and likely functions to retain CpaB inside the cell. Limited proteolysis of spheroplasts revealed that the C-terminal domain of CpaB is exposed to the periplasm, suggesting that this is the site where CpaA and CpaB interact Last, we show that CpaB does not abolish the proteolytic activity of CpaA against human Factor V. We conclude that CpaA is, to the best of our knowledge, the first characterized, virulence factor secreted by species.
© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
0 Communities
1 Members
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12 MeSH Terms
Helicobacter pylori and its secreted immunomodulator VacA protect against anaphylaxis in experimental models of food allergy.
Kyburz A, Urban S, Altobelli A, Floess S, Huehn J, Cover TL, Müller A
(2017) Clin Exp Allergy 47: 1331-1341
MeSH Terms: Allergens, Anaphylaxis, Animals, Bacterial Proteins, CpG Islands, Cytokines, DNA Methylation, Disease Models, Animal, Food Hypersensitivity, Helicobacter pylori, Immunoglobulin E, Immunologic Factors, Male, Mice, Peanut Hypersensitivity, Spleen, T-Lymphocytes, Regulatory
Show Abstract · Added March 21, 2018
BACKGROUND - Food allergy is an increasingly common health problem in Western populations. Epidemiological studies have suggested both positive and negative associations between food allergy and infection with the gastric bacterium Helicobacter pylori.
OBJECTIVE - The objective of this work was to investigate whether experimental infection with H. pylori, or prophylactic treatment with H. pylori-derived immunomodulatory molecules, affects the onset and severity of food allergy, either positively or negatively.
METHODS - We infected neonatal C57BL/6 or C3H mice with H. pylori or treated animals with H. pylori components (bacterial lysate or the immunomodulator VacA) and subsequently subjected them to four different protocols for food allergy induction, using either ovalbumin or peanut extract as allergens for sensitization and challenge. Readouts included anaphylaxis scoring, quantification of allergen-specific serum IgE and IgG1 and of the mast cell protease MCPT1, as well as splenic T-helper-2 cell-derived cytokine production. Mesenteric lymph node CD4 FoxP3 regulatory T cells were subjected to flow cytometric quantification and sorting followed by qRT-PCR, and to DNA methylation analyses of the Treg-specific demethylated region (TSDR) within the FOXP3 locus.
RESULTS - Mice that had been infected with H. pylori or treated with H. pylori-derived immunomodulators showed reduced anaphylaxis upon allergen sensitization and challenge, irrespective of the allergen used. Most of the immunologic assays confirmed a protective effect of H. pylori. CD4 FoxP3 T cells were more abundant in protected mice and exhibited a stable Treg phenotype characterized by FOXP3 TSDR demethylation.
CONCLUSIONS AND CLINICAL RELEVANCE - Helicobacter pylori confers protection against the anaphylaxis associated with ovalbumin and peanut allergy and affects the epigenome of T cells, thereby promoting stable Treg differentiation and functionality. Prophylactic treatment with H. pylori-derived immunomodulators appears to be a promising strategy for food allergy prevention.
© 2017 John Wiley & Sons Ltd.
0 Communities
1 Members
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17 MeSH Terms
Improving Spleen Volume Estimation Via Computer-assisted Segmentation on Clinically Acquired CT Scans.
Xu Z, Gertz AL, Burke RP, Bansal N, Kang H, Landman BA, Abramson RG
(2016) Acad Radiol 23: 1214-20
MeSH Terms: Adult, Aged, Aged, 80 and over, Female, Humans, Male, Middle Aged, Organ Size, Spleen, Tomography, X-Ray Computed
Show Abstract · Added November 2, 2016
OBJECTIVES - Multi-atlas fusion is a promising approach for computer-assisted segmentation of anatomic structures. The purpose of this study was to evaluate the accuracy and time efficiency of multi-atlas segmentation for estimating spleen volumes on clinically acquired computed tomography (CT) scans.
MATERIALS AND METHODS - Under an institutional review board approval, we obtained 294 de-identified (Health Insurance Portability and Accountability Act-compliant) abdominal CT scans on 78 subjects from a recent clinical trial. We compared five pipelines for obtaining splenic volumes: Pipeline 1 - manual segmentation of all scans, Pipeline 2 - automated segmentation of all scans, Pipeline 3 - automated segmentation of all scans with manual segmentation for outliers on a rudimentary visual quality check, and Pipelines 4 and 5 - volumes derived from a unidimensional measurement of craniocaudal spleen length and three-dimensional splenic index measurements, respectively. Using Pipeline 1 results as ground truth, the accuracies of Pipelines 2-5 (Dice similarity coefficient, Pearson correlation, R-squared, and percent and absolute deviation of volume from ground truth) were compared for point estimates of splenic volume and for change in splenic volume over time. Time cost was also compared for Pipelines 1-5.
RESULTS - Pipeline 3 was dominant in terms of both accuracy and time cost. With a Pearson correlation coefficient of 0.99, average absolute volume deviation of 23.7 cm(3), and time cost of 1 minute per scan, Pipeline 3 yielded the best results. The second-best approach was Pipeline 5, with a Pearson correlation coefficient of 0.98, absolute deviation of 46.92 cm(3), and time cost of 1 minute 30 seconds per scan. Manual segmentation (Pipeline 1) required 11 minutes per scan.
CONCLUSION - A computer-automated segmentation approach with manual correction of outliers generated accurate splenic volumes with reasonable time efficiency.
Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
0 Communities
2 Members
0 Resources
10 MeSH Terms
Novel HLA-A2-restricted human metapneumovirus epitopes reduce viral titers in mice and are recognized by human T cells.
Hastings AK, Gilchuk P, Joyce S, Williams JV
(2016) Vaccine 34: 2663-70
MeSH Terms: Adult, Animals, CD8-Positive T-Lymphocytes, Epitopes, T-Lymphocyte, HLA-A2 Antigen, Humans, Lung, Metapneumovirus, Mice, Inbred C57BL, Mice, Transgenic, Middle Aged, Paramyxoviridae Infections, Spleen
Show Abstract · Added April 25, 2016
Human metapneumovirus (HMPV) is a major cause of morbidity and mortality from acute lower respiratory tract illness, with most individuals seropositive by age five. Despite the presence of neutralizing antibodies, secondary infections are common and can be severe in young, elderly, and immunocompromised persons. Preclinical vaccine studies for HMPV have suggested a need for a balanced antibody and T cell immune response to enhance protection and avoid lung immunopathology. We infected transgenic mice expressing human HLA-A*0201 with HMPV and used ELISPOT to screen overlapping and predicted epitope peptides. We identified six novel HLA-A2 restricted CD8(+) T cell (TCD8) epitopes, with M39-47 (M39) immunodominant. Tetramer staining detected M39-specific TCD8 in lungs and spleen of HMPV-immune mice. Immunization with adjuvant-formulated M39 peptide reduced lung virus titers upon challenge. Finally, we show that TCD8 from HLA-A*0201 positive humans recognize M39 by IFNγ ELISPOT and tetramer staining. These results will facilitate HMPV vaccine development and human studies.
Copyright © 2016 Elsevier Ltd. All rights reserved.
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1 Members
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13 MeSH Terms
IL-15 Superagonist Expands mCD8+ T, NK and NKT Cells after Burn Injury but Fails to Improve Outcome during Burn Wound Infection.
Patil NK, Luan L, Bohannon JK, Guo Y, Hernandez A, Fensterheim B, Sherwood ER
(2016) PLoS One 11: e0148452
MeSH Terms: Adaptive Immunity, Animals, Burns, CD8-Positive T-Lymphocytes, Cytokines, Disease Models, Animal, Humans, Interleukin-15, Killer Cells, Natural, Liver, Lymphocyte Activation, Lymphocyte Count, Lymphocyte Subsets, Male, Mice, Mice, Inbred BALB C, Natural Killer T-Cells, Pseudomonas Infections, Pseudomonas aeruginosa, Receptors, Interleukin-15, Recombinant Fusion Proteins, Spleen, Wound Infection
Show Abstract · Added February 18, 2016
BACKGROUND - Severely burned patients are highly susceptible to opportunistic infections and sepsis, owing to the loss of the protective skin barrier and immunological dysfunction. Interleukin-15 (IL-15) belongs to the IL-2 family of common gamma chain cytokines and stimulates the proliferation and activation of T (specifically memory CD8), NK and NKT cells. It has been shown to preserve T cell function and improve survival during cecal ligation and puncture (CLP)-induced sepsis in mice. However, the therapeutic efficacy of IL-15 or IL-15 superagonist (SA) during infection after burn injury has not been evaluated. Moreover, very few, if any, studies have examined, in detail, the effect of burn injury and infection on the adaptive immune system. Thus, we examined the effect of burn and sepsis on adaptive immune cell populations and the effect of IL-15 SA treatment on the host response to infection.
METHODS - Mice were subjected to a 35% total body surface area burn, followed by wound infection with Pseudomonas aeruginosa. In some experiments, IL-15 SA was administered after burn injury, but before infection. Leukocytes in spleen, liver and peritoneal cavity were characterized using flow cytometry. Bacterial clearance, organ injury and survival were also assessed.
RESULTS - Burn wound infection led to a significant decline in total white blood cell and lymphocyte counts and induced organ injury and sepsis. Burn injury caused decline in CD4+ and CD8+ T cells in the spleen, which was worsened by infection. IL-15 treatment inhibited this decline and significantly increased cell numbers and activation, as determined by CD69 expression, of CD4+, CD8+, B, NK and NKT cells in the spleen and liver after burn injury. However, IL-15 SA treatment failed to prevent burn wound sepsis-induced loss of CD4+, CD8+, B, NK and NKT cells and failed to improve bacterial clearance and survival.
CONCLUSION - Cutaneous burn injury and infection cause significant adaptive immune dysfunction. IL-15 SA does not augment host resistance to burn wound sepsis in mice despite inducing proliferation and activation of lymphocyte subsets.
0 Communities
1 Members
0 Resources
23 MeSH Terms
Anti-Tumor Effects after Adoptive Transfer of IL-12 Transposon-Modified Murine Splenocytes in the OT-I-Melanoma Mouse Model.
Galvan DL, O'Neil RT, Foster AE, Huye L, Bear A, Rooney CM, Wilson MH
(2015) PLoS One 10: e0140744
MeSH Terms: Adoptive Transfer, Animals, DNA Transposable Elements, HeLa Cells, Humans, Interleukin-12, Melanoma, Mice, Mice, Inbred NOD, Mice, SCID, Neoplasms, Experimental, Spleen, T-Lymphocytes
Show Abstract · Added March 7, 2016
Adoptive transfer of gene modified T cells provides possible immunotherapy for patients with cancers refractory to other treatments. We have previously used the non-viral piggyBac transposon system to gene modify human T cells for potential immunotherapy. However, these previous studies utilized adoptive transfer of modified human T cells to target cancer xenografts in highly immunodeficient (NOD-SCID) mice that do not recapitulate an intact immune system. Currently, only viral vectors have shown efficacy in permanently gene-modifying mouse T cells for immunotherapy applications. Therefore, we sought to determine if piggyBac could effectively gene modify mouse T cells to target cancer cells in a mouse cancer model. We first demonstrated that we could gene modify cells to express murine interleukin-12 (p35/p40 mIL-12), a transgene with proven efficacy in melanoma immunotherapy. The OT-I melanoma mouse model provides a well-established T cell mediated immune response to ovalbumin (OVA) positive B16 melanoma cells. B16/OVA melanoma cells were implanted in wild type C57Bl6 mice. Mouse splenocytes were isolated from C57Bl6 OT-I mice and were gene modified using piggyBac to express luciferase. Adoptive transfer of luciferase-modified OT-I splenocytes demonstrated homing to B16/OVA melanoma tumors in vivo. We next gene-modified OT-I cells to express mIL-12. Adoptive transfer of mIL-12-modified mouse OT-I splenocytes delayed B16/OVA melanoma tumor growth in vivo compared to control OT-I splenocytes and improved mouse survival. Our results demonstrate that the piggyBac transposon system can be used to gene modify splenocytes and mouse T cells for evaluating adoptive immunotherapy strategies in immunocompetent mouse tumor models that may more directly mimic immunotherapy applications in humans.
0 Communities
1 Members
0 Resources
13 MeSH Terms
Acute Viral Respiratory Infection Rapidly Induces a CD8+ T Cell Exhaustion-like Phenotype.
Erickson JJ, Lu P, Wen S, Hastings AK, Gilchuk P, Joyce S, Shyr Y, Williams JV
(2015) J Immunol 195: 4319-30
MeSH Terms: Acute Disease, Animals, CD8-Positive T-Lymphocytes, Cluster Analysis, Gene Expression Profiling, Host-Pathogen Interactions, Humans, Lung, Metapneumovirus, Mice, Congenic, Mice, Inbred C57BL, Mice, Knockout, Oligonucleotide Array Sequence Analysis, Paramyxoviridae Infections, Phenotype, Programmed Cell Death 1 Receptor, Respiratory Tract Infections, Spleen, Transcriptome
Show Abstract · Added October 2, 2015
Acute viral infections typically generate functional effector CD8(+) T cells (TCD8) that aid in pathogen clearance. However, during acute viral lower respiratory infection, lung TCD8 are functionally impaired and do not optimally control viral replication. T cells also become unresponsive to Ag during chronic infections and cancer via signaling by inhibitory receptors such as programmed cell death-1 (PD-1). PD-1 also contributes to TCD8 impairment during viral lower respiratory infection, but how it regulates TCD8 impairment and the connection between this state and T cell exhaustion during chronic infections are unknown. In this study, we show that PD-1 operates in a cell-intrinsic manner to impair lung TCD8. In light of this, we compared global gene expression profiles of impaired epitope-specific lung TCD8 to functional spleen TCD8 in the same human metapneumovirus-infected mice. These two populations differentially regulate hundreds of genes, including the upregulation of numerous inhibitory receptors by lung TCD8. We then compared the gene expression of TCD8 during human metapneumovirus infection to those in acute or chronic lymphocytic choriomeningitis virus infection. We find that the immunophenotype of lung TCD8 more closely resembles T cell exhaustion late into chronic infection than do functional effector T cells arising early in acute infection. Finally, we demonstrate that trafficking to the infected lung alone is insufficient for TCD8 impairment or inhibitory receptor upregulation, but that viral Ag-induced TCR signaling is also required. Our results indicate that viral Ag in infected lungs rapidly induces an exhaustion-like state in lung TCD8 characterized by progressive functional impairment and upregulation of numerous inhibitory receptors.
Copyright © 2015 by The American Association of Immunologists, Inc.
0 Communities
1 Members
0 Resources
19 MeSH Terms
Neonatal CD71+ Erythroid Cells Do Not Modify Murine Sepsis Mortality.
Wynn JL, Scumpia PO, Stocks BT, Romano-Keeler J, Alrifai MW, Liu JH, Kim AS, Alford CE, Matta P, Weitkamp JH, Moore DJ
(2015) J Immunol 195: 1064-70
MeSH Terms: Adoptive Transfer, Animals, Antibodies, Antigens, CD, Bone Marrow Cells, CD11b Antigen, Endotoxins, Erythroid Cells, Female, Fetal Blood, Humans, Male, Mice, Mice, Inbred C57BL, Receptors, Transferrin, Reticulocytes, Sepsis, Spleen
Show Abstract · Added June 24, 2015
Sepsis is a major cause of neonatal mortality and morbidity worldwide. A recent report suggested that murine neonatal host defense against infection could be compromised by immunosuppressive CD71(+) erythroid splenocytes. We examined the impact of CD71(+) erythroid splenocytes on murine neonatal mortality to endotoxin challenge or polymicrobial sepsis and characterized circulating CD71(+) erythroid (CD235a(+)) cells in human neonates. Adoptive transfer or an Ab-mediated reduction in neonatal CD71(+) erythroid splenocytes did not alter murine neonatal survival to endotoxin challenge or polymicrobial sepsis challenge. Ex vivo immunosuppression of stimulated adult CD11b(+) cells was not limited to neonatal splenocytes; it also occurred with adult and neonatal bone marrow. Animals treated with anti-CD71 Ab showed reduced splenic bacterial load following bacterial challenge compared with isotype-treated mice. However, adoptive transfer of enriched CD71(+) erythroid splenocytes to CD71(+)-reduced animals did not reduce bacterial clearance. Human CD71(+)CD235a(+) cells were common among cord blood mononuclear cells and were shown to be reticulocytes. In summary, a lack of effect on murine survival to polymicrobial sepsis following adoptive transfer or diminution of CD71(+) erythroid splenocytes under these experimental conditions suggests that the impact of these cells on neonatal infection risk and progression may be limited. An unanticipated immune priming effect of anti-CD71 Ab treatment, rather than a reduction in immunosuppressive CD71(+) erythroid splenocytes, was likely responsible for the reported enhanced bacterial clearance. In humans, the well-described rapid decrease in circulating reticulocytes after birth suggests that they may have a limited role in reducing inflammation secondary to microbial colonization.
Copyright © 2015 by The American Association of Immunologists, Inc.
0 Communities
3 Members
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18 MeSH Terms
Spleen supports a pool of innate-like B cells in white adipose tissue that protects against obesity-associated insulin resistance.
Wu L, Parekh VV, Hsiao J, Kitamura D, Van Kaer L
(2014) Proc Natl Acad Sci U S A 111: E4638-47
MeSH Terms: Adipose Tissue, White, Animals, B-Lymphocytes, CD5 Antigens, Diet, High-Fat, Immunity, Innate, Insulin Resistance, Interleukin-10, Lymphocyte Count, Male, Mice, Inbred C57BL, Obesity, Peritoneal Cavity, Phenotype, Spleen, Splenectomy
Show Abstract · Added January 20, 2015
Lipid accumulation in obesity triggers a low-grade inflammation that results from an imbalance between pro- and anti-inflammatory components of the immune system and acts as the major underlying mechanism for the development of obesity-associated diseases, notably insulin resistance and type 2 diabetes. Innate-like B cells are a subgroup of B cells that respond to innate signals and modulate inflammatory responses through production of immunomodulatory mediators such as the anti-inflammatory cytokine IL-10. In this study, we examined innate-like B cells in visceral white adipose tissue (VAT) and the relationship of these cells with their counterparts in the peritoneal cavity and spleen during diet-induced obesity (DIO) in mice. We show that a considerable number of innate-like B cells bearing a surface phenotype distinct from the recently identified "adipose natural regulatory B cells" populate VAT of lean animals, and that spleen represents a source for the recruitment of these cells in VAT during DIO. However, demand for these cells in the expanding VAT outpaces their recruitment during DIO, and the obese environment in VAT further impairs their function. We further show that removal of splenic precursors of innate-like B cells through splenectomy exacerbates, whereas supplementation of these cells via adoptive transfer ameliorates, DIO-associated insulin resistance. Additional adoptive transfer experiments pointed toward a dominant role of IL-10 in mediating the protective effects of innate-like B cells against DIO-induced insulin resistance. These findings identify spleen-supplied innate-like B cells in VAT as previously unrecognized players and therapeutic targets for obesity-associated diseases.
0 Communities
2 Members
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16 MeSH Terms