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Innate Immunity

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https://www.readbyqxmd.com/read/28409545/high-affinity-caspase-4-binding-to-lps-presented-as-high-molecular-mass-aggregates-or-in-outer-membrane-vesicles
#1
Mark A Wacker, Athmane Teghanemt, Jerrold P Weiss, Jason H Barker
Caspases of the non-canonical inflammasome (caspases -4, -5, and -11) directly bind endotoxin (LOS/LPS) and can be activated in the absence of any co-factors. Models of LPS-induced caspase activation have postulated that 1:1 binding of endotoxin monomers to caspase trigger caspase oligomerization and activation, analogous to that established for endotoxin-induced activation of MD-2/TLR4. However, using metabolically radiolabeled LOS and LPS, we now show high affinity and selective binding of caspase-4 to high molecular mass aggregates of purified endotoxin and to endotoxin-rich outer membrane vesicles without formation of 1:1 endotoxin:caspase complexes...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409544/hypoxia-and-the-hypoxia-regulated-transcription-factor-hif-1%C3%AE-suppress-the-host-defence-of-airway-epithelial-cells
#2
Markus Polke, Frederik Seiler, Philipp M Lepper, Andreas Kamyschnikow, Frank Langer, Dominik Monz, Christian Herr, Robert Bals, Christoph Beisswenger
Chronic diseases of the respiratory tract, such as cystic fibrosis, are associated with mucosal and systemic hypoxia. Innate immune functions of airway epithelial cells are required to prevent and control infections of the lung parenchyma. The transcription factor hypoxia-inducible factor 1α (HIF-1α) regulates cellular adaptation to low oxygen conditions. Here, we show that hypoxia and HIF-1α regulate innate immune mechanisms of cultured human bronchial epithelial cells (HBECs). Exposure of primary HBECs to hypoxia or the prolyl hydroxylase inhibitor dimethyloxaloylglycine (DMOG) resulted in a significantly decreased expression of inflammatory mediators (IL-6, IFN-γ-induced protein 10) in response to ligands for TLRs (flagellin, polyI:C) and Pseudomonas aeruginosa, whereas the expression of inflammatory mediators was not affected by hypoxia or DMOG in the absence of microbial factors...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409543/ccr-2-neutralization-augments-murine-fresh-bmc-activation-by-staphylococcus-aureus-via-two-distinct-mechanisms-at-the-level-of-ros-production-and-cytokine-response
#3
Ajeya Nandi, Biswadev Bishayi
CCR-2 signaling regulates recruitment of monocytes from the bone marrow into the bloodstream and then to sites of infection. We sought to determine whether CCL-2/CCR-2 signaling is involved in the killing of Staphylococcus aureus by murine bone marrow cells (BMCs). The intermittent link of reactive oxygen species (ROS)-NF-κB/p38-MAPK-mediated CCL-2 production in CCR-2 signaling prompted us to determine whether neutralization of CCR-2 augments the response of murine fresh BMCs (FBMCs) after S. aureus infection...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409542/inhibitory-receptor-fc%C3%AE-riib-mediates-the-effects-of-igg-on-a-phagosome-acidification-and-a-sequential-dephosphorylation-system-comprising-ships-and-inpp4a
#4
Tomohiro Segawa, Kaoru Hazeki, Kiyomi Nigorikawa, Atsuko Nukuda, Tomoki Tanizawa, Kenshiro Miyamoto, Shin Morioka, Osamu Hazeki
The relative abundance of phosphoinositide (PI) species on the phagosome membrane fluctuates over the course of phagocytosis. PtdIns(3,4,5)P3 and PtdIns(3,4)P2 rapidly increase in the forming of the phagocytic cup, following which they disappear after sealing of the cup. In the present study, we monitored the clearance of these PI species using the enhanced green fluorescent protein-fused pleckstrin homology domain of Akt, a fluorescence probe that binds both PtdIns(3,4,5)P3 and PtdIns(3,4)P2 in Raw 264.7 macrophages...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409541/a-dual-positive-and-negative-regulation-of-monocyte-activation-by-leukocyte-ig-like-receptor-b4-depends-on-the-position-of-the-tyrosine-residues-in-its-itims
#5
Mijeong Park, Robert W Liu, Hongyan An, Carolyn L Geczy, Paul S Thomas, Nicodemus Tedla
The leukocyte Ig-like receptor B4 (LILRB4) is an inhibitory cell surface receptor, primarily expressed on mono-myeloid cells. It contains 2 C-type Ig-like extracellular domains and a long cytoplasmic domain that contains three intracellular immunoreceptor tyrosine-based inhibitory motifs (ITIMs). Data suggest that LILRB4 suppresses Fc receptor-dependent monocyte functions via its ITIMs, but relative contributions of the three ITIMs are not characterised. To address this, tyrosine (Tyr) residues at positions 337, 389 and 419 were single, double or triple mutated to phenylalanine and stably transfected into a human monocytic cell line, THP-1...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409540/comparison-of-cellular-assays-for-tlr-activation-and-development-of-a-species-specific-reporter-cell-line-for-cattle
#6
Kata Tombácz, Duncan Mwangi, Dirk Werling, Amanda J Gibson
PRRs are sentinels of the innate immune system, with TLRs being the most important. Assays for TLR ligand interactions have been used to gain insights into their function and signaling pathways. As significant differences exist between species with regard to ligand recognition, it is necessary to adapt these tools for TLRs of other species. In the present work, we describe a species-specific cell-based assay adapted for the analysis of single PRRs. Human embryonic kidney 293T cells were stably transfected with the NF-κB-inducible reporter gene secreted embryonic alkaline phosphatase (SEAP) together with bovine TLR2...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28409539/particulate-matter-air-pollution-from-the-city-of-quito-ecuador-activates-inflammatory-signaling-pathways-in%C3%A2-vitro
#7
Victoria M Cevallos, Valeria Díaz, Cherilyn M Sirois
Automobile traffic, industrial processes and natural phenomena cause notable air pollution, including gaseous and particulate contaminants, in urban centers. Exposure to particulate matter (PM) air pollution affects human health, and has been linked to respiratory, cardiovascular and neurological diseases. The mechanisms underlying inflammation in these diverse diseases, and to what extent health effects are different for PM obtained from different sources or locations, are still unclear. This study investigated the in vitro toxicity of ambient course (PM10) and fine (PM2...
May 2017: Innate Immunity
https://www.readbyqxmd.com/read/28359219/modification-of-sample-processing-for-the-limulus-amebocyte-lysate-assay-enhances-detection-of-inflammogenic-endotoxin-in-intact-bacteria-and-organic-dust
#8
Kimberly A Hoppe Parr, Suzana Hađina, Brita Kilburg-Basnyat, Yifang Wang, Dulce Chavez, Peter S Thorne, Jerrold P Weiss
The pro-inflammatory potency and causal relationship with asthma of inhaled endotoxins have underscored the importance of accurately assessing the endotoxin content of organic dusts. The Limulus amebocyte lysate (LAL) assay has emerged as the preferred assay, but its ability to measure endotoxin in intact bacteria and organic dusts with similar sensitivity as purified endotoxin is unknown. We used metabolically radiolabeled Neisseria meningitidis and both rough and smooth Escherichia coli to compare dose-dependent activation in the LAL with purified endotoxin from these bacteria and shed outer membrane (OM) blebs...
April 2017: Innate Immunity
https://www.readbyqxmd.com/read/28359218/the-critical-role-of-myeloperoxidase-in-streptococcus-pneumoniae-clearance-and-tissue-damage-during-mouse-acute-otitis-media
#9
Yun Xiang, Chunfang Jin, Wei Wang, Zimeng Wang, Yifei Huang, Fangmei Fan, Yurong Ma, Xuemei Zhang, Wenchun Xu, Yibing Yin, Yujuan He
We have recently reported that neutrophils play a pivotal role in innate defense against Streptococcus pneumoniae ( Spn) during mouse acute otitis media (AOM). However, the underlying mechanism remains unclear. By constructing models of pneumococcal AOM in C57BL/6 mice and using a specific inhibitor in vivo, we investigated the role of myeloperoxidase (MPO), one of the most important protein components of neutrophils. Experiment results showed a significant increase in MPO production of the recruited neutrophils in Spn-infected mice...
April 2017: Innate Immunity
https://www.readbyqxmd.com/read/28359217/efferocytosis-induced-prostaglandin-e2-production-impairs-alveolar-macrophage-effector-functions-during-streptococcus-pneumoniae-infection
#10
Ana Cg Salina, Tais P Souza, Carlos H Serezani, Alexandra I Medeiros
Alveolar macrophages (AMs) are multitasking cells that maintain lung homeostasis by clearing apoptotic cells (efferocytosis) and performing antimicrobial effector functions. Different PRRs have been described to be involved in the binding and capture of non-opsonized Streptococcus pneumoniae, such as TLR-2, mannose receptor (MR) and scavenger receptors (SRs). However, the mechanism by which the ingestion of apoptotic cells negatively influences the clearance of non-opsonized S. pneumoniae remains to be determined...
April 2017: Innate Immunity
https://www.readbyqxmd.com/read/28120642/a-novel-mouse-model-of-conditional-irak-m-deficiency-in-myeloid-cells-application-in-lung-pseudomonas-aeruginosa-infection
#11
Di Jiang, Jennifer Matsuda, Reena Berman, Niccolette Schaefer, Connor Stevenson, James Gross, Bicheng Zhang, Amelia Sanchez, Liwu Li, Hong Wei Chu
Myeloid cells such as macrophages are critical to innate defense against infection. IL-1 receptor-associated kinase M (IRAK-M) is a negative regulator of TLR signaling during bacterial infection, but the role of myeloid cell IRAK-M in bacterial infection is unclear. Our goal was to generate a novel conditional knockout mouse model to define the role of myeloid cell IRAK-M during bacterial infection. Myeloid cell-specific IRAK-M knockout mice were generated by crossing IRAK-M floxed mice with LysM-Cre knock-in mice...
February 2017: Innate Immunity
https://www.readbyqxmd.com/read/27932520/myeloid-derived-nf-%C3%AE%C2%BAb-negative-regulation-of-pu-1-and-c-ebp-%C3%AE-driven-pro-inflammatory-cytokine-production-restrains-lps-induced-shock
#12
Simone Vanoni, Yi-Ting Tsai, Amanda Waddell, Lisa Waggoner, Jared Klarquist, Senad Divanovic, Kasper Hoebe, Kris A Steinbrecher, Simon P Hogan
Sepsis is a life-threatening event predominantly caused by Gram-negative bacteria. Bacterial infection causes a pronounced macrophage (MΦ) and dendritic cell activation that leads to excessive pro-inflammatory cytokine IL-1β, IL-6 and TNF-α production (cytokine storm), resulting in endotoxic shock. Previous experimental studies have revealed that inhibiting NF-κB signaling ameliorates disease symptoms; however, the contribution of myeloid p65 in endotoxic shock remains elusive. In this study, we demonstrate increased mortality in mice lacking p65 in the myeloid lineage (p65(Δmye)) compared with wild type mice upon ultra-pure LPS challenge...
February 2017: Innate Immunity
https://www.readbyqxmd.com/read/27913792/genetic-engineering-approach-to-develop-next-generation-reagents-for-endotoxin-quantification
#13
Hikaru Mizumura, Norihiko Ogura, Jun Aketagawa, Maki Aizawa, Yuki Kobayashi, Shun-Ichiro Kawabata, Toshio Oda
The bacterial endotoxin test, which uses amebocyte lysate reagents of horseshoe crab origin, is a sensitive, reproducible and simple assay to measure endotoxin concentration. To develop sustainable raw materials for lysate reagents that do not require horseshoe crabs, three recombinant protease zymogens (factor C, derived from mammalian cells; factor B; and the proclotting enzyme derived from insect cells) were prepared using a genetic engineering technique. Recombinant cascade reagents (RCRs) were then prepared to reconstruct the reaction cascade in the amebocyte lysate reagent...
February 2017: Innate Immunity
https://www.readbyqxmd.com/read/27884946/analysis-of-the-caenorhabditis-elegans-innate-immune-response-to-coxiella-burnetii
#14
James M Battisti, Lance A Watson, Myo T Naung, Adam M Drobish, Ekaterina Voronina, Michael F Minnick
The nematode Caenorhabditis elegans is well established as a system for characterization and discovery of molecular mechanisms mediating microbe-specific inducible innate immune responses to human pathogens. Coxiella burnetii is an obligate intracellular bacterium that causes a flu-like syndrome in humans (Q fever), as well as abortions in domesticated livestock, worldwide. Initially, when wild type C. elegans (N2 strain) was exposed to mCherry-expressing C. burnetii (CCB) a number of overt pathological manifestations resulted, including intestinal distension, deformed anal region and a decreased lifespan...
February 2017: Innate Immunity
https://www.readbyqxmd.com/read/28443393/cd14-gene-silencing-alters-the-microrna-expression-profile-of-raw264-7-cells-stimulated-by-brucella-melitensis-infection
#15
Hui Rong, Hanwei Jiao, Yongchang Hao, Feng Pang, Guohua Li, Dongmei Peng, Yaying Li, Yuanzhi Wang, Hui Zhang, Quanshui Fan, Fengyang Wang, Chuangfu Chen, Li Du
Innate recognition of Brucella spp. is a key step in the activation of inflammation. CD14 binds PAMPs and is involved in LPS-induced pro-inflammatory cytokine release. Previously we showed that knock down of CD14 in RAW264.7 macrophages disrupted Brucella-host interactions. However, its effect on the macrophage microRNA (miRNA) expression profile, especially after stimulation by Brucella infection, is still unclear. To identify miRNAs involved in the macrophage response to Brucella infection, we performed miRNA expression profiling of CD14 knock-down RAW264...
January 1, 2017: Innate Immunity
https://www.readbyqxmd.com/read/28443392/sex-differences-in-the-pro-inflammatory-cytokine-response-to-endotoxin-unfold-in%C3%A2-vivo-but-not-ex-vivo-in-healthy-humans
#16
Alexander Wegner, Sven Benson, Laura Rebernik, Ingo Spreitzer, Marcus Jäger, Manfred Schedlowski, Sigrid Elsenbruch, Harald Engler
Clinical data indicate that inflammatory responses differ across sexes, but the mechanisms remain elusive. Herein, we assessed in vivo and ex vivo cytokine responses to bacterial endotoxin in healthy men and women to elucidate the role of systemic and cellular factors underlying sex differences in inflammatory responses. Participants received an i.v. injection of low-dose endotoxin (0.4 ng/kg body mass), and plasma TNF-α and IL-6 responses were analyzed over a period of 6 h. In parallel, ex vivo cytokine production was measured in endotoxin-stimulated blood samples obtained immediately before in vivo endotoxin administration...
January 1, 2017: Innate Immunity
https://www.readbyqxmd.com/read/28399692/the-interrelationship-between-phagocytosis-autophagy-and-formation-of-neutrophil-extracellular-traps-following-infection-of-human-neutrophils-by-streptococcus-pneumoniae
#17
Ihsan Ullah, Neil D Ritchie, Tom J Evans
Neutrophils play an important role in the innate immune response to infection with Streptococcus pneumoniae, the pneumococcus. Pneumococci are phagocytosed by neutrophils and undergo killing after ingestion. Other cellular processes may also be induced, including autophagy and the formation of neutrophil extracellular traps (NETs), which may play a role in bacterial eradication. We set out to determine how these different processes interacted following pneumococcal infection of neutrophils, and the role of the major pneumococcal toxin pneumolysin in these various pathways...
January 1, 2017: Innate Immunity
https://www.readbyqxmd.com/read/28205451/sialylation-of-porphyromonas-gingivalis-lps-and-its-effect-on-bacterial-host-interactions
#18
Svetislav S Zaric, Mark J Lappin, Catherine R Fulton, Fionnuala T Lundy, Wilson A Coulter, Christopher R Irwin
Porphyromonas gingivalis produces different LPS isoforms with significant structural variations of their lipid A and O-antigen moieties that can affect its pro-inflammatory and bone-resorbing potential. We show here, for the first time, that P. gingivalis LPS isolated from W83 strain is highly sialylated and possesses significantly reduced inflammatory potential compared with less sialylated ATCC 33277 strain LPS. Nevertheless, the reduction in the endotoxin activity is not mediated by the presence of sialic acid LPS moieties as the sialic acid-free LPS produced by the mutant W83 strain exhibits a similar inflammatory potential to the wild type strain...
January 1, 2017: Innate Immunity
https://www.readbyqxmd.com/read/28162006/age-dependent-cellular-reactions-of-the-human-immune-system-of-humanized-nod-scid-gamma-mice-on-lps-stimulus
#19
Anja Rodewohl, Johanna Scholbach, Anna Leichsenring, Margarethe Köberle, Franziska Lange
Despite sepsis being a life-threatening disease, targeted drugs that improve the therapy of affected patients are still lacking. Infants and adults differ in the maturity level of their immune system and this results in distinct reactions to Gram-negative bacteria. To study reactions of human immune cells in vivo, we used NOD scid gamma mice transplanted with human CD34(+) stem cells to engraft a functional human immune system. Human cells undergo differentiation and maturation in these mice after transplantation and, accordingly, animals were divided into two groups: 8-13 wk and 15-22 wk after transplantation...
January 1, 2017: Innate Immunity
https://www.readbyqxmd.com/read/28142301/the-immunomodulatory-potential-of-leonurus-cardiaca-extract-in-relation-to-endothelial-cells-and-platelets
#20
Beata Sadowska, Bartłomiej Micota, Marek Różalski, Małgorzata Redzynia, Marcin Różalski
The immunomodulatory activity of Leonurus cardiaca L. polyphenol-rich extract (LCE) was tested in vitro on HUVECs to explore its potential therapeutic usefulness in the treatment of inflammatory lesions. The phytochemical composition of LCE, its antioxidant and cytotoxic activity, and the influence of LCE on NO and platelet-activating factor (PAF) secretion by HUVECs and platelet aggregation were all assessed. Total polyphenol contents in LCE reached 137.0 ± 0.8 mg/g, with hydroxycinnamic acid derivatives as the predominant phenolic compounds...
January 1, 2017: Innate Immunity
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