scholarly journals Purified Streptococcus pneumoniae Endopeptidase O (PepO) Enhances Particle Uptake by Macrophages in a Toll-Like Receptor 2- and miR-155-Dependent Manner

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Hua Yao ◽  
Hong Zhang ◽  
Kai Lan ◽  
Hong Wang ◽  
Yufeng Su ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Host Defense ◽  
Defense Response ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Content Type ◽  
Host Defense Response ◽  
Toll Like Receptor 2 ◽  
In Cells

ABSTRACT Insights into the host-microbial virulence factor interaction, especially the immune signaling mechanisms, could provide novel prevention and treatment options for pneumococcal diseases. Streptococcus pneumoniae endopeptidase O (PepO) is a newly discovered and ubiquitously expressed pneumococcal virulence protein. A PepO-mutant strain showed impaired adherence to and invasion of host cells compared with the isogenic wild-type strain. It is still unknown whether PepO is involved in the host defense response to pneumococcal infection. Here, we demonstrated that PepO could enhance phagocytosis of Streptococcus pneumoniae and Staphylococcus aureus by peritoneal exudate macrophages (PEMs). Further studies showed that PepO stimulation upregulated the expression of microRNA-155 (miR-155) in PEMs in a time- and dose-dependent manner. PepO-induced enhanced phagocytosis was decreased in cells transfected with an inhibitor of miR-155, while it was increased in cells transfected with a mimic of miR-155. We also revealed that PepO-induced upregulation of miR-155 in PEMs was mediated by Toll-like receptor 2 (TLR2)–NF-κB signaling and that the increased expression of miR-155 downregulated expression of SHIP1. Taken together, these results indicate that PepO induces upregulation of miR-155 in PEMs, contributing to enhanced phagocytosis and host defense response to pneumococci and Staphylococcus aureus.

scholarly journals Staphylococcus aureus Releases Proinflammatory Membrane Vesicles To Resist Antimicrobial Fatty Acids

mSphere ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Arnaud Kengmo Tchoupa ◽  
Andreas Peschel
Keyword(s):  
Fatty Acids ◽  
Staphylococcus Aureus ◽  
Immune Responses ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Innate Immune ◽  
Toll Like Receptor ◽  
Content Type ◽  
Healthy Humans ◽  
Toll Like Receptor 2

ABSTRACT Staphylococcus aureus is a major pathogen, which colonizes one in three otherwise healthy humans. This significant spread of S. aureus is largely due to its ability to circumvent innate immune responses, including antimicrobial fatty acids (AFAs) on the skin and in nasal secretions. In response to AFAs, S. aureus swiftly induces resistance mechanisms, which have yet to be completely elucidated. Here, we identify membrane vesicle (MV) release as a resistance strategy used by S. aureus to sequester host-specific AFAs. MVs protect S. aureus against a wide array of AFAs. Strikingly, beside MV production, S. aureus modulates MV composition upon exposure to AFAs. MVs purified from bacteria grown in the presence of linoleic acid display a distinct protein content and are enriched in lipoproteins, which strongly activate Toll-like receptor 2 (TLR2). Cumulatively, our findings reveal the protective capacities of MVs against AFAs, which are counteracted by an increased TLR2-mediated innate immune response. IMPORTANCE The nares of one in three humans are colonized by Staphylococcus aureus. In these environments, and arguably on all mucosal surfaces, bacteria encounter fatty acids with antimicrobial properties. Our study uncovers that S. aureus releases membrane vesicles (MVs) that act as decoys to protect the bacterium against antimicrobial fatty acids (AFAs). The AFA-neutralizing effects of MVs were neither strain specific nor restricted to one particular AFA. Hence, MVs may represent “public goods” playing an overlooked role in shaping bacterial communities in AFA-rich environments such as the skin and nose. Intriguingly, in addition to MV biogenesis, S. aureus modulates MV composition in response to exposure to AFAs, including an increased release of lipoproteins. These MVs strongly stimulate the innate immunity via Toll-like receptor 2 (TLR2). TLR2-mediated inflammation, which helps to fight infections, may exacerbate inflammatory disorders like atopic dermatitis. Our study highlights intricate immune responses preventing infections from colonizing bacteria.

scholarly journals NOD2 Stimulation by Staphylococcus aureus-Derived Peptidoglycan Is Boosted by Toll-Like Receptor 2 Costimulation with Lipoproteins in Dendritic Cells

2014 ◽  
Vol 82 (11) ◽  
pp. 4681-4688 ◽  
Author(s):  
Holger Schäffler ◽  
Dogan Doruk Demircioglu ◽  
Daniel Kühner ◽  
Sarah Menz ◽  
Annika Bender ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Dendritic Cells ◽  
Immune System ◽  
Cytokine Secretion ◽  
Toll Like Receptor ◽  
Necrosis Factor Alpha ◽  
Content Type ◽  
Murine Bone Marrow ◽  
J774 Cells ◽  
Toll Like Receptor 2

ABSTRACTMutations in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) play an important role in the pathogenesis of Crohn's disease. NOD2 is an intracellular pattern recognition receptor (PRR) that senses bacterial peptidoglycan (PGN) structures, e.g., muramyl dipeptide (MDP). Here we focused on the effect of more-cross-linked, polymeric PGN fragments (PGNpol) in the activation of the innate immune system. In this study, the effect of combined NOD2 and Toll-like receptor 2 (TLR2) stimulation was examined compared to single stimulation of the NOD2 receptor alone. PGNpol species derived from a lipoprotein-containingStaphylococcus aureusstrain (SA113) and a lipoprotein-deficient strain (SA113 Δlgt) were isolated. While PGNpol constitutes a combined NOD2 and TLR2 ligand, lipoprotein-deficient PGNpolΔlgtleads to activation of the immune system only via the NOD2 receptor. Murine bone marrow-derived dendritic cells (BMDCs), J774 cells, and Mono Mac 6 (MM6) cells were stimulated with these ligands. Cytokines (interleukin-6 [IL-6], IL-12p40, and tumor necrosis factor alpha [TNF-α]) as well as DC activation and maturation parameters were measured. Stimulation with PGNpolΔlgtdid not lead to enhanced cytokine secretion or DC activation and maturation. However, stimulation with PGNpol led to strong cytokine secretion and subsequent DC maturation. These results were confirmed in MM6 and J774 cells. We showed that the NOD2-mediated activation of DCs with PGNpol was dependent on TLR2 costimulation. Therefore, signaling via both receptors leads to a more potent activation of the immune system than that with stimulation via each receptor alone.

scholarly journals Toll-Like Receptor 2 Ligand Pretreatment Attenuates Retinal Microglial Inflammatory Response but Enhances Phagocytic Activity toward Staphylococcus aureus

2012 ◽  
Vol 80 (6) ◽  
pp. 2076-2088 ◽  
Author(s):  
Travis Kochan ◽  
Anuj Singla ◽  
Joaquin Tosi ◽  
Ashok Kumar
Keyword(s):  
Staphylococcus Aureus ◽  
Inflammatory Response ◽  
Phagocytic Activity ◽  
Toll Like Receptor ◽  
Innate Response ◽  
Content Type ◽  
Proinflammatory Mediators ◽  
Retinal Microglia ◽  
Tlr2 Ligand ◽  
Toll Like Receptor 2

ABSTRACTStaphylococcus aureusis a leading cause of severe endophthalmitis, which often results in vision loss in some patients. Previously, we showed that Toll-like receptor 2 (TLR2) ligand pretreatment prevented the development of staphylococcal endophthalmitis in mice and suggested that microglia might be involved in this protective effect (Kumar A, Singh CN, Glybina IV, Mahmoud TH, Yu FS. J. Infect. Dis. 201:255–263, 2010). The aim of the present study was to understand how microglial innate response is modulated by TLR2 ligand pretreatment. Here, we demonstrate thatS. aureusinfection increased the CD11b+CD45+microglial/macrophage population in the C57BL/6 mouse retina. Using cultured primary retinal microglia and a murine microglial cell line (BV-2), we found that these cells express TLR2 and that its expression is increased upon stimulation with bacteria or an exclusive TLR2 ligand, Pam3Cys. Furthermore, challenge of primary retinal microglia withS. aureusand its cell wall components peptidoglycan (PGN) and lipoteichoic acid (LTA) induced the secretion of proinflammatory mediators (tumor necrosis factor alpha [TNF-α] and MIP-2). This innate response was attenuated by a function-blocking anti-TLR2 antibody or by small interfering RNA (siRNA) knockdown of TLR2. In order to assess the modulation of the innate response, microglia were pretreated with a low dose (0.1 or 1 μg/ml) of Pam3Cys and then challenged with liveS. aureus. Our data showed thatS. aureus-induced production of proinflammatory mediators is dramatically reduced in pretreated microglia. Importantly, microglia pretreated with the TLR2 agonist phagocytosed significantly more bacteria than unstimulated cells. Together, our data suggest that TLR2 plays an important role in retinal microglial innate response toS. aureus, and its sensitization inhibits inflammatory response while enhancing phagocytic activity.

scholarly journals Streptococcus pneumoniae PepO promotes host anti-infection defense via autophagy in a Toll-like receptor 2/4 dependent manner

Virulence ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 270-282 ◽  
Author(s):  
Zhaoche Shu ◽  
Jun Yuan ◽  
Hong Wang ◽  
Jinghui Zhang ◽  
Sijie Li ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Toll Like Receptor 2

scholarly journals Toll-Like Receptor 2-Dependent Protection against Pneumococcal Carriage by Immunization with Lipidated Pneumococcal Proteins

2014 ◽  
Vol 82 (5) ◽  
pp. 2079-2086 ◽  
Author(s):  
Kristin Moffitt ◽  
Mojca Skoberne ◽  
Angela Howard ◽  
L. Cristina Gavrilescu ◽  
Todd Gierahn ◽  
...  
Keyword(s):  
Protective Efficacy ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Protein Fusion ◽  
Protein Subunit ◽  
Content Type ◽  
Human Embryonic Kidney Cells ◽  
Pneumococcal Carriage ◽  
Toll Like Receptor 2 ◽  
Pneumococcal Colonization

ABSTRACTInfections withStreptococcus pneumoniaecause substantial morbidity and mortality, particularly in children in developing nations. Polysaccharide-conjugate vaccines provide protection against both invasive disease and colonization, but their use in developing countries is limited by restricted serotype coverage and expense of manufacture. Using proteomic screens, we recently identified several antigens that protected mice from pneumococcal colonization in a CD4+T cell- and interleukin-17A (IL-17A)-dependent manner. Since several of these proteins are lipidated, we hypothesized that their immunogenicity and impact on colonization are in part due to activation of Toll-like receptor 2 (TLR2), a receptor for lipoproteins. Here we show that lipidated versions of the antigens elicited significantly higher activation of both human embryonic kidney cells engineered to express TLR2 (HEK-TLR2) and wild-type (WT) murine macrophages than nonlipidated mutant antigens. Lipoprotein-stimulated secretion of proinflammatory cytokines was ∼10× to ∼100× lower in murine TLR2-deficient macrophages than in WT macrophages. Subcutaneous immunization of C57BL/6 mice with protein subunit vaccines containing one or two of these lipoproteins or protein fusion constructs bearing N-terminal lipid adducts elicited a robust IL-17A response and a significant reduction in colonization compared with immunization with alum alone. In contrast, immunization ofTlr2−/−mice elicited no detectable IL-17A response and no protection against pneumococcal colonization. These experiments suggest that the lipid moieties enhance the immunogenicity and protective efficacy of pneumococcal TH17 antigens through activation of TLR2. Thus, triggering TLR2 with an antigen-specific protein subunit formulation is a possible strategy for the development of a serotype-independent pneumococcal vaccine that would reduce pneumococcal carriage.

scholarly journals Staphylococcal Superantigen-Like Protein 3 Binds to the Toll-Like Receptor 2 Extracellular Domain and Inhibits Cytokine Production Induced by Staphylococcus aureus, Cell Wall Component, or Lipopeptides in Murine Macrophages

2012 ◽  
Vol 80 (8) ◽  
pp. 2816-2825 ◽  
Author(s):  
Ryosuke Yokoyama ◽  
Saotomo Itoh ◽  
Go Kamoshida ◽  
Takemasa Takii ◽  
Satoshi Fujii ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Sialic Acid ◽  
Extracellular Domain ◽  
Raw 264.7 Cells ◽  
Raw 264.7 ◽  
Toll Like Receptor ◽  
Content Type ◽  
Toll Like Receptor 2 ◽  
Binding Residues ◽  
Tlr2 Ligands

ABSTRACTStaphylococcal superantigen-like proteins (SSLs) are a family of exoproteins sharing structural similarity with superantigens, but no superantigenic activity. Corresponding host target proteins or receptors against a portion of SSLs in the family have been identified. In this study, we show that SSL3 specifically binds to Toll-like receptor 2 (TLR2) and inhibits the stimulation of macrophages by TLR2 ligands. An approximately 100-kDa protein was recovered by using recombinant His-tagged SSL3-conjugated Sepharose from the lysate of porcine spleen, and the protein was identified as porcine TLR2 by peptide mass fingerprinting analysis. The SSL3-conjugated Sepharose recovered human and mouse TLR2 but not TLR4 from human neutrophils and mouse macrophage RAW 264.7 cells, as well as a recombinant TLR2 extracellular domain chimera protein. The production levels of interleukin 12 (IL-12) from mouse macrophages treated with heat-killedStaphylococcus aureusand of tumor necrosis factor alpha (TNF-α) from RAW 264.7 cells induced by peptidoglycan or lipopeptide TLR2 ligands were strongly suppressed in the presence of SSL3. The mutation of consensus sialic acid-containing glycan-binding residues in SSL3 did not abrogate the binding ability to TLR2 or inhibitory activity on TLR2, indicating that the interaction of SSL3 with TLR2 was independent of the sialic acid-containing glycan-binding residues. These findings demonstrate that SSL3 is able to bind the extracellular domain of TLR2 and interfere with TLR2 function. The present study provides a novel mechanism of SSL3 in immune evasion ofS. aureusvia interfering with its recognition by innate immune cells.

scholarly journals The Poly-γ-d-Glutamic Acid Capsule Surrogate of the Bacillus anthracis Capsule Is a Novel Toll-Like Receptor 2 Agonist

2015 ◽  
Vol 83 (10) ◽  
pp. 3847-3856 ◽  
Author(s):  
Jun Ho Jeon ◽  
Hae-Ri Lee ◽  
Min-Hee Cho ◽  
Ok-Kyu Park ◽  
Jungchan Park ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Bacillus Anthracis ◽  
Map Kinases ◽  
Chinese Hamster Ovary Cells ◽  
Mouse Bone Marrow ◽  
Dependent Manner ◽  
Toll Like Receptor ◽  
Content Type ◽  
Tnf Α ◽  
Toll Like Receptor 2

Bacillus anthracisis a pathogenic Gram-positive bacterium that causes a highly lethal infectious disease, anthrax. The poly-γ-d-glutamic acid (PGA) capsule is one of the major virulence factors ofB. anthracis, along with exotoxins. PGA enablesB. anthracisto escape phagocytosis and immune surveillance. Our previous study showed that PGA activates the human macrophage cell line THP-1 and human dendritic cells, resulting in the production of the proinflammatory cytokine interleukin-1β (IL-1β) (M. H. Cho et al., Infect Immun 78:387–392, 2010,http://dx.doi.org/10.1128/IAI.00956-09). Here, we investigated PGA-induced cytokine responses and related signaling pathways in mouse bone marrow-derived macrophages (BMDMs) usingBacillus licheniformisPGA as a surrogate forB. anthracisPGA. Upon exposure to PGA, BMDMs produced proinflammatory mediators, including tumor necrosis factor alpha (TNF-α), IL-6, IL-12p40, and monocyte chemoattractant protein 1 (MCP-1), in a concentration-dependent manner. PGA stimulated Toll-like receptor 2 (TLR2) but not TLR4 in Chinese hamster ovary cells expressing either TLR2 or TLR4. The ability of PGA to induce TNF-α and IL-6 was retained in TLR4−/−but not TLR2−/−BMDMs. Blocking experiments with specific neutralizing antibodies for TLR1, TLR6, and CD14 showed that TLR6 and CD14 also were necessary for PGA-induced inflammatory responses. Furthermore, PGA enhanced activation of mitogen-activated protein (MAP) kinases and nuclear factor-kappa B (NF-κB), which are responsible for expression of proinflammatory cytokines. Additionally, PGA-induced TNF-α production was abrogated not only in MyD88−/−BMDMs but also in BMDMs pretreated with inhibitors of MAP kinases and NF-κB. These results suggest that immune responses induced by PGA occur via TLR2, TLR6, CD14, and MyD88 through activation of MAP kinase and NF-κB pathways.

scholarly journals Ceftaroline Activity against Bacterial Pathogens Frequently Isolated in U.S. Medical Centers: Results from Five Years of the AWARE Surveillance Program

2015 ◽  
Vol 59 (4) ◽  
pp. 2458-2461 ◽  
Author(s):  
Helio S. Sader ◽  
Robert K. Flamm ◽  
Jennifer M. Streit ◽  
David J. Farrell ◽  
Ronald N. Jones
Keyword(s):  
Staphylococcus Aureus ◽  
Streptococcus Pneumoniae ◽  
Bacterial Pathogens ◽  
Surveillance Program ◽  
Broth Microdilution ◽  
Methicillin Resistant ◽  
Content Type ◽  
Medical Centers ◽  
Resistant Strains

ABSTRACTA total of 84,704 isolates were collected from 191 medical centers in 2009 to 2013 and tested for susceptibility to ceftaroline and comparator agents by broth microdilution methods. Ceftaroline inhibited allStaphylococcus aureusisolates at ≤2 μg/ml and was very active against methicillin-resistant strains (MIC at which 90% of the isolates tested are inhibited [MIC90], 1 μg/ml; 97.6% susceptible). AmongStreptococcus pneumoniaeisolates, the highest ceftaroline MIC was 0.5 μg/ml, and ceftaroline activity against the most commonEnterobacteriaceaespecies (MIC50, 0.12 μg/ml; 78.9% susceptible) was similar to that of ceftriaxone (MIC50, ≤0.25 μg/ml; 86.8% susceptible).

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