scholarly journals Staphylococcus aureus Biofilm-Conditioned Medium Impairs Macrophage-Mediated Antibiofilm Immune Response by Upregulating KLF2 Expression

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Talib Alboslemy ◽  
Bing Yu ◽  
Tara Rogers ◽  
Min-Ho Kim
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Conditioned Medium ◽  
Innate Immune Response ◽  
Immune Defense ◽  
Innate Immune ◽  
Raw 264.7 Cells ◽  
Raw 264.7 ◽  
Content Type ◽  
Cell Functions

ABSTRACT Staphylococcus aureus infections associated with the formation of biofilms on medical implants or host tissue play a critical role in the persistence of chronic infections. One critical mechanism of biofilm infection that leads to persistent infection lies in the capacity of biofilms to evade the macrophage-mediated innate immune response. It is now increasingly apparent that microorganisms exploit the negative regulatory mechanisms of the pattern recognition receptor (PRR)-mediated inflammatory response to subvert host cell functions by using various virulence factors. However, the detailed molecular mechanism, along with the identity of a target molecule, underlying the evasion of the macrophage-mediated innate immune response against S. aureus infection associated with biofilm formation remains to be elucidated. Here, using an in vitro culture model of murine macrophage-like RAW 264.7 cells, we demonstrate that S. aureus biofilm-conditioned medium significantly attenuated the capacity for macrophage bactericidal and proinflammatory responses. Importantly, the responses were associated with attenuated activation of NF-κB and increased expression of Kruppel-like factor 2 (KLF2) in RAW 264.7 cells. Small interfering RNA (siRNA)-mediated silencing of KLF2 in RAW 264.7 cells could restore the activation of NF-κB toward the bactericidal activity and generation of proinflammatory cytokines in the presence of S. aureus biofilm-conditioned medium. Collectively, our results suggest that factors secreted from S. aureus biofilms might exploit the KLF2-dependent negative regulatory mechanism to subvert macrophage-mediated innate immune defense against S. aureus biofilms.

scholarly journals Genetic basis of host innate immune response in mastitis caused by Staphylococcus aureus

2012 ◽  
Vol 4 ◽  
pp. 405-409 ◽  
Author(s):  
Adrianna Pawlik ◽  
Grażyna Sender ◽  
Rafał Starzyński ◽  
Agnieszka Korwin-Kossakowska
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Innate Immune Response ◽  
Genetic Basis ◽  
Innate Immune ◽  
Host Innate Immune Response

scholarly journals Ursodeoxycholic Acid (UDCA) Mitigates the Host Inflammatory Response during Clostridioides difficile Infection by Altering Gut Bile Acids

2020 ◽  
Vol 88 (6) ◽  
Author(s):  
Jenessa A. Winston ◽  
Alissa J. Rivera ◽  
Jingwei Cai ◽  
Rajani Thanissery ◽  
Stephanie A. Montgomery ◽  
...  
Keyword(s):  
Immune Response ◽  
Bile Acid ◽  
Inflammatory Response ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Colonization Resistance ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides difficile infection (CDI) is associated with increasing morbidity and mortality posing an urgent threat to public health. Recurrence of CDI after successful treatment with antibiotics is high, thus necessitating discovery of novel therapeutics against this enteric pathogen. Administration of the secondary bile acid ursodeoxycholic acid (UDCA; ursodiol) inhibits the life cycles of various strains of C. difficile in vitro, suggesting that the FDA-approved formulation of UDCA, known as ursodiol, may be able to restore colonization resistance against C. difficile in vivo. However, the mechanism(s) by which ursodiol is able to restore colonization resistance against C. difficile remains unknown. Here, we confirmed that ursodiol inhibits C. difficile R20291 spore germination and outgrowth, growth, and toxin activity in a dose-dependent manner in vitro. In a murine model of CDI, exogenous administration of ursodiol resulted in significant alterations in the bile acid metabolome with little to no changes in gut microbial community structure. Ursodiol pretreatment resulted in attenuation of CDI pathogenesis early in the course of disease, which coincided with alterations in the cecal and colonic inflammatory transcriptome, bile acid-activated receptors nuclear farnesoid X receptor (FXR) and transmembrane G-protein-coupled membrane receptor 5 (TGR5), which are able to modulate the innate immune response through signaling pathways such as NF-κB. Although ursodiol pretreatment did not result in a consistent decrease in the C. difficile life cycle in vivo, it was able to attenuate an overly robust inflammatory response that is detrimental to the host during CDI. Ursodiol remains a viable nonantibiotic treatment and/or prevention strategy against CDI. Likewise, modulation of the host innate immune response via bile acid-activated receptors FXR and TGR5 represents a new potential treatment strategy for patients with CDI.

scholarly journals A Mouse Model to Assess Innate Immune Response to Staphylococcus aureus Infection

10.3791/59015 ◽  
2019 ◽  
Author(s):  
Leif S. Anderson ◽  
Mack B. Reynolds ◽  
Kathryn R. Rivara ◽  
Lloyd S. Miller ◽  
Scott I. Simon
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Mouse Model ◽  
Innate Immune Response ◽  
Innate Immune

scholarly journals Promotion of Colonization and Virulence by Cholera Toxin Is Dependent on Neutrophils

2013 ◽  
Vol 81 (9) ◽  
pp. 3338-3345 ◽  
Author(s):  
Jessica Queen ◽  
Karla J. F. Satchell
Keyword(s):  
Immune Response ◽  
Cholera Toxin ◽  
Innate Immune Response ◽  
Host Response ◽  
Survival Rates ◽  
Innate Immune ◽  
Infection Model ◽  
High Dose ◽  
Content Type ◽  
Inflammatory Protein

ABSTRACTThe innate immune response toVibrio choleraeinfection is poorly understood, but this knowledge is critical for the design of safe, effective vaccines. Using an adult mouse intestinal infection model, this study examines the contribution of neutrophils to host immunity, as well as the effect of cholera toxin and other secreted factors on this response. Depletion of neutrophils from mice with anti-Ly6G IA8 monoclonal antibody led to similar survival rates of mice infected with low or moderate doses of toxigenicV. choleraeEl Tor O1. At a high dose, neutropenic mice showed increased rates of survival compared to neutrophil-replete animals. Expression of cholera toxin was found to be protective to the neutropenic host, and this phenotype can be replicated by the administration of purified toxin. Neutrophils do not effectively clear colonizing bacteria from the small intestine, nor do they alter induction of early immune-modulating signals. In both neutropenic and neutrophil-replete animals, the local response to infection is characterized by expression of interleukin 6 (IL-6), IL-10, and macrophage inflammatory protein 2 alpha (MIP-2). Overall, these data indicate that the innate immune response to toxigenicV. choleraeinfection differs dramatically from the host response to nontoxigenic infection or vaccination, where neutrophils are protective to the host. In the absence of neutrophils, cholera toxin induces immunomodulatory effects that increase host survival. In cholera toxin-producing strains, similar to nontoxigenic infection, accessory toxins are critical to virulence, indicating that cholera toxin and the other secreted toxins modulate the host response by different mechanisms, with both contributing to bacterial persistence and virulence.

scholarly journals Leptospira interrogans Catalase Is Required for Resistance to H2O2and for Virulence

2012 ◽  
Vol 80 (11) ◽  
pp. 3892-3899 ◽  
Author(s):  
Azad Eshghi ◽  
Kristel Lourdault ◽  
Gerald L. Murray ◽  
Thanatchaporn Bartpho ◽  
Rasana W. Sermswan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reactive Oxygen Species ◽  
Immune Response ◽  
Innate Immune Response ◽  
Reactive Oxygen ◽  
Innate Immune ◽  
Leptospira Interrogans ◽  
Oxygen Species ◽  
Content Type ◽  
Host Innate Immune Response

ABSTRACTPathogenicLeptospiraspp. are likely to encounter higher concentrations of reactive oxygen species induced by the host innate immune response. In this study, we characterizedLeptospira interroganscatalase (KatE), the only annotated catalase found within pathogenicLeptospiraspecies, by assessing its role in resistance to H2O2-induced oxidative stress and during infection in hamsters. PathogenicL. interrogansbacteria had a 50-fold-higher survival rate under H2O2-induced oxidative stress than did saprophyticL. biflexabacteria, and this was predominantly catalase dependent. We also characterized KatE, the only annotated catalase found within pathogenicLeptospiraspecies. Catalase assays performed with recombinant KatE confirmed specific catalase activity, while protein fractionation experiments localized KatE to the bacterial periplasmic space. The insertional inactivation ofkatEin pathogenicLeptospirabacteria drastically diminished leptospiral viability in the presence of extracellular H2O2and reduced virulence in an acute-infection model. Combined, these results suggest thatL. interrogansKatE confersin vivoresistance to reactive oxygen species induced by the host innate immune response.

scholarly journals Transcriptome Profiling of the Virus-Induced Innate Immune Response in Pteropus vampyrus and Its Attenuation by Nipah Virus Interferon Antagonist Functions

2015 ◽  
Vol 89 (15) ◽  
pp. 7550-7566 ◽  
Author(s):  
Nicole B. Glennon ◽  
Omar Jabado ◽  
Michael K. Lo ◽  
Megan L. Shaw
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Mammalian Cells ◽  
Nipah Virus ◽  
A549 Cells ◽  
Hendra Virus ◽  
Innate Immune ◽  
Viral Control ◽  
Content Type ◽  
Pteropus Vampyrus

ABSTRACTBats are important reservoirs for several viruses, many of which cause lethal infections in humans but have reduced pathogenicity in bats. As the innate immune response is critical for controlling viruses, the nature of this response in bats and how it may differ from that in other mammals are of great interest. Using next-generation transcriptome sequencing (mRNA-seq), we profiled the transcriptional response ofPteropus vampyrusbat kidney (PVK) cells to Newcastle disease virus (NDV), an avian paramyxovirus known to elicit a strong innate immune response in mammalian cells. ThePteropusgenus is a known reservoir of Nipah virus (NiV) and Hendra virus (HeV). Analysis of the 200 to 300 regulated genes showed that genes for interferon (IFN) and antiviral pathways are highly upregulated in NDV-infected PVK cells, including genes for beta IFN, RIG-I, MDA5, ISG15, and IRF1. NDV-infected cells also upregulated several genes not previously characterized to be antiviral, such as RND1, SERTAD1, CHAC1, and MORC3. In fact, we show that MORC3 is induced by both IFN and NDV infection in PVK cells but is not induced by either stimulus in human A549 cells. In contrast to NDV infection, HeV and NiV infection of PVK cells failed to induce these innate immune response genes. Likewise, an attenuated response was observed in PVK cells infected with recombinant NDVs expressing the NiV IFN antagonist proteins V and W. This study provides the first global profile of a robust virus-induced innate immune response in bats and indicates that henipavirus IFN antagonist mechanisms are likely active in bat cells.IMPORTANCEBats are the reservoir host for many highly pathogenic human viruses, including henipaviruses, lyssaviruses, severe acute respiratory syndrome coronavirus, and filoviruses, and many other viruses have also been isolated from bats. Viral infections are reportedly asymptomatic or heavily attenuated in bat populations. Despite their ecological importance to viral maintenance, research into their immune system and mechanisms for viral control has only recently begun. Nipah virus and Hendra virus are two paramyxoviruses associated with high mortality rates in humans and whose reservoir is thePteropusgenus of bats. Greater knowledge of the innate immune response ofP. vampyrusbats to viral infection may elucidate how bats serve as a reservoir for so many viruses.

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