Roles of neutrophil β2 integrins in kinetics of bacteremia, extravasation, and tick acquisition of Anaplasma phagocytophila in mice

Blood ◽  
2003 ◽  
Vol 101 (8) ◽  
pp. 3257-3264 ◽  
Author(s):  
Dori L. Borjesson ◽  
Scott I. Simon ◽  
Emir Hodzic ◽  
Hilde E. V. DeCock ◽  
Christie M. Ballantyne ◽  
...  
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Etiologic Agent ◽  
Pathogen Transmission ◽  
Mouse Strains ◽  
Tick Feeding ◽  
Tick Saliva ◽  
Knock Out ◽  
Feeding Site ◽  
Β2 Integrin ◽  
Β2 Integrins

AbstractTick saliva contains anti-inflammatory and immunosuppressive substances that facilitate blood feeding and enhance tick-vectored pathogen transmission, including Anaplasma phagocytophila,an etiologic agent of granulocytic ehrlichiosis. As such, inflammation at a tick-feeding site is strikingly different than that typically observed at other sites of inflammation. Up-regulation of CD11b/CD18 occurs in host granulocytes following interaction or infection withA phagocytophila, and the absence of CD11b/CD18 results in early increases in bacteremia. We hypothesized that β2 integrin–dependent infection kinetics and leukocyte extravasation are important determinants of neutrophil trafficking to, and pathogen acquisition at, tick-feeding sites.A phagocytophila infection kinetics were evaluated in CD11a/CD18, CD11b/CD18, and CD18 knock-out mice using quantitative polymerase chain reaction (PCR) of blood, ticks, and skin biopsies in conjunction with histopathology. A marked increase in the rate ofA phagocytophila infection of neutrophils and pathogen burden in blood followed tick feeding. Infection kinetics were modified by β2 integrin expression and systemic neutrophil counts. Significant neutrophil-pathogen trafficking was observed to both suture and tick sites. Despite the prominent role for β2 integrins in neutrophil arrest in flowing blood, successful pathogen acquisition by ticks occurred in the absence of β2 integrins. Establishment of feeding pools that rely less on leukocyte trafficking and more on small hemorrhages may explain the ready amplification of A phagocytophila DNA from ticks infested on CD11/CD18-deficient mouse strains.

scholarly journals Spotted Fever GroupRickettsiaInfection and Transmission Dynamics inAmblyomma maculatum

2019 ◽  
Vol 87 (4) ◽  
Author(s):  
Chanakan Suwanbongkot ◽  
Ingeborg M. Langohr ◽  
Emma K. Harris ◽  
Wellesley Dittmar ◽  
Rebecca C. Christofferson ◽  
...  
Keyword(s):  
Salivary Glands ◽  
Spotted Fever ◽  
Attachment Site ◽  
Spotted Fever Group ◽  
Tick Feeding ◽  
Tick Saliva ◽  
Content Type ◽  
Feeding Site ◽  
Vertebrate Hosts ◽  
Tick Salivary Glands

ABSTRACTTick vectors are capable of transmitting several rickettsial species to vertebrate hosts, resulting in various levels of disease. Studies have demonstrated the transmissibility of both rickettsial pathogens and novelRickettsiaspecies or strains with unknown pathogenicity to vertebrate hosts during tick blood meal acquisition; however, the quantitative nature of transmission remains unknown. We tested the hypothesis that if infection severity is a function of the rickettsial load delivered during tick transmission, then a more virulent spotted fever group (SFG)Rickettsiaspecies is transmitted at higher levels during tick feeding. UsingAmblyomma maculatumcohorts infected withRickettsia parkerior “CandidatusRickettsia andeanae,” a quantitative PCR (qPCR) assay was employed to quantify rickettsiae in tick salivary glands and saliva, as well as in the vertebrate hosts at the tick attachment site over the duration of tick feeding. Significantly greater numbers ofR. parkerithan of “Ca. Rickettsia andeanae” rickettsiae were present in tick saliva and salivary glands and in the vertebrate hosts at the feeding site during tick feeding. Microscopy demonstrated the presence of both rickettsial species in tick salivary glands, and immunohistochemical analysis of the attachment site identified localizedR. parkeri, but not “Ca. Rickettsia andeanae,” in the vertebrate host. Lesions were also distinct and more severe in vertebrate hosts exposed toR. parkerithan in those exposed to “Ca. Rickettsia andeanae.” The specific factors that contribute to the generation of a sustained rickettsial infection and subsequent disease have yet to be elucidated, but the results of this study suggest that the rickettsial load in ticks and during transmission may be an important element.

scholarly journals Binding of Rap1 and Riam to Talin1 Fine-Tune β2 Integrin Activity During Leukocyte Trafficking

2021 ◽  
Vol 12 ◽  
Author(s):  
Thomas Bromberger ◽  
Sarah Klapproth ◽  
Ina Rohwedder ◽  
Jasmin Weber ◽  
Robert Pick ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Small Gtpase ◽  
Mouse Strains ◽  
Leukocyte Rolling ◽  
Leukocyte Trafficking ◽  
Β2 Integrin ◽  
Adhesion Sites ◽  
T Cell Homing ◽  
Simultaneous Loss ◽  
Β2 Integrins

β2 integrins mediate key processes during leukocyte trafficking. Upon leukocyte activation, the structurally bent β2 integrins change their conformation towards an extended, intermediate and eventually high affinity conformation, which mediate slow leukocyte rolling and firm arrest, respectively. Translocation of talin1 to integrin adhesion sites by interactions with the small GTPase Rap1 and the Rap1 effector Riam precede these processes. Using Rap1 binding mutant talin1 and Riam deficient mice we show a strong Riam-dependent T cell homing process to lymph nodes in adoptive transfer experiments and by intravital microscopy. Moreover, neutrophils from compound mutant mice exhibit strongly increased rolling velocities to inflamed cremaster muscle venules compared to single mutants. Using Hoxb8 cell derived neutrophils generated from the mutant mouse strains, we show that both pathways regulate leukocyte rolling and adhesion synergistically by inducing conformational changes of the β2 integrin ectodomain. Importantly, a simultaneous loss of both pathways results in a rolling phenotype similar to talin1 deficient neutrophils suggesting that β2 integrin regulation primarily occurs via these two pathways.

scholarly journals Borrelia burgdorferi infection modifies protein content in saliva of Ixodes scapularis nymphs

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Tae Kwon Kim ◽  
Lucas Tirloni ◽  
Emily Bencosme-Cuevas ◽  
Tae Heung Kim ◽  
Jolene K. Diedrich ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Protein Content ◽  
Mammalian Cells ◽  
Protein Identification ◽  
Ixodes Scapularis ◽  
Tick Feeding ◽  
Tick Saliva ◽  
Feeding Site ◽  
Copper Zinc Superoxide Dismutase ◽  
Glycolysis Pathway

Abstract Background Lyme disease (LD) caused by Borrelia burgdorferi is the most prevalent tick-borne disease. There is evidence that vaccines based on tick proteins that promote tick transmission of B. burgdorferi could prevent LD. As Ixodes scapularis nymph tick bites are responsible for most LD cases, this study sought to identify nymph tick saliva proteins associated with B. burgdorferi transmission using LC-MS/MS. Tick saliva was collected using a non-invasive method of stimulating ticks (uninfected and infected: unfed, and every 12 h during feeding through 72 h, and fully-fed) to salivate into 2% pilocarpine-PBS for protein identification using LC-MS/MS. Results We identified a combined 747 tick saliva proteins of uninfected and B. burgdorferi infected ticks that were classified into 25 functional categories: housekeeping-like (48%), unknown function (18%), protease inhibitors (9%), immune-related (6%), proteases (8%), extracellular matrix (7%), and small categories that account for <5% each. Notably, B. burgdorferi infected ticks secreted high number of saliva proteins (n=645) than uninfected ticks (n=376). Counter-intuitively, antimicrobial peptides, which function to block bacterial infection at tick feeding site were suppressed 23-85 folds in B. burgdorferi infected ticks. Similar to glycolysis enzymes being enhanced in mammalian cells exposed to B. burgdorferi : eight of the 10-glycolysis pathway enzymes were secreted at high abundance by B. burgdorferi infected ticks. Of significance, rabbits exposed to B. burgdorferi infected ticks acquired potent immunity that caused 40-60% mortality of B. burgdorferi infected ticks during the second infestation compared to 15-28% for the uninfected. This might be explained by ELISA data that show that high expression levels of immunogenic proteins in B. burgdorferi infected ticks. Conclusion Data here suggest that B. burgdorferi infection modified protein content in tick saliva to promote its survival at the tick feeding site. For instance, enzymes; copper/zinc superoxide dismutase that led to production of H2O2 that is toxic to B. burgdorferi were suppressed, while, catalase and thioredoxin that neutralize H2O2, and pyruvate kinase which yields pyruvate that protects Bb from H2O2 killing were enhanced. We conclude data here is an important resource for discovery of effective antigens for a vaccine to prevent LD.

scholarly journals Induced Transient Immune Tolerance in Ticks and Vertebrate Host: A Keystone of Tick-Borne Diseases?

2021 ◽  
Vol 12 ◽  
Author(s):  
Nathalie Boulanger ◽  
Stephen Wikel
Keyword(s):  
Immune Tolerance ◽  
Pathogen Transmission ◽  
Bioactive Molecules ◽  
Vertebrate Host ◽  
Infectious Agents ◽  
Global Public Health ◽  
Tick Feeding ◽  
Tick Saliva ◽  
Immune Defenses ◽  
Tick Infection

Ticks and tick transmitted infectious agents are increasing global public health threats due to increasing abundance, expanding geographic ranges of vectors and pathogens, and emerging tick-borne infectious agents. Greater understanding of tick, host, and pathogen interactions will contribute to development of novel tick control and disease prevention strategies. Tick-borne pathogens adapt in multiple ways to very different tick and vertebrate host environments and defenses. Ticks effectively pharmacomodulate by its saliva host innate and adaptive immune defenses. In this review, we examine the idea that successful synergy between tick and tick-borne pathogen results in host immune tolerance that facilitates successful tick infection and feeding, creates a favorable site for pathogen introduction, modulates cutaneous and systemic immune defenses to establish infection, and contributes to successful long-term infection. Tick, host, and pathogen elements examined here include interaction of tick innate immunity and microbiome with tick-borne pathogens; tick modulation of host cutaneous defenses prior to pathogen transmission; how tick and pathogen target vertebrate host defenses that lead to different modes of interaction and host infection status (reservoir, incompetent, resistant, clinically ill); tick saliva bioactive molecules as important factors in determining those pathogens for which the tick is a competent vector; and, the need for translational studies to advance this field of study. Gaps in our understanding of these relationships are identified, that if successfully addressed, can advance the development of strategies to successfully disrupt both tick feeding and pathogen transmission.

scholarly journals Deletion of Kif5c Does Not Alter Prion Disease Tempo or Spread in Mouse Brain

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1391
Author(s):  
Brent Race ◽  
Katie Williams ◽  
Chase Baune ◽  
James F. Striebel ◽  
Clayton W. Winkler ◽  
...  
Keyword(s):  
Prion Disease ◽  
Molecular Motors ◽  
Prion Diseases ◽  
Mouse Strains ◽  
Survival Times ◽  
Knock Out ◽  
Transport Vesicles ◽  
The Central Nervous System ◽  
Knock Out Mice ◽  
Scrapie Strains

In prion diseases, the spread of infectious prions (PrPSc) is thought to occur within nerves and across synapses of the central nervous system (CNS). However, the mechanisms by which PrPSc moves within axons and across nerve synapses remain undetermined. Molecular motors, including kinesins and dyneins, transport many types of intracellular cargo. Kinesin-1C (KIF5C) has been shown to transport vesicles carrying the normal prion protein (PrPC) within axons, but whether KIF5C is involved in PrPSc axonal transport is unknown. The current study tested whether stereotactic inoculation in the striatum of KIF5C knock-out mice (Kif5c−/−) with 0.5 µL volumes of mouse-adapted scrapie strains 22 L or ME7 would result in an altered rate of prion spreading and/or disease timing. Groups of mice injected with each strain were euthanized at either pre-clinical time points or following the development of prion disease. Immunohistochemistry for PrP was performed on brain sections and PrPSc distribution and tempo of spread were compared between mouse strains. In these experiments, no differences in PrPSc spread, distribution or survival times were observed between C57BL/6 and Kif5c−/− mice.

scholarly journals The Absence of TLR4 Prevents Fetal Brain Injury in the Setting of Intrauterine Inflammation

2018 ◽  
Vol 26 (8) ◽  
pp. 1082-1093 ◽  
Author(s):  
Natalia M. Tulina ◽  
Amy G. Brown ◽  
Guillermo O. Barila ◽  
Michal A. Elovitz
Keyword(s):  
Brain Injury ◽  
Notch Signaling ◽  
Signaling Pathway ◽  
Quantitative Polymerase Chain Reaction ◽  
Fetal Brain ◽  
Notch Signaling Pathway ◽  
Mouse Strains ◽  
Enzyme Linked Immunosorbent Assay ◽  
Tlr4 Signaling ◽  
Tlr4 Signaling Pathway

Background: Exposure to intrauterine inflammation during pregnancy is linked to brain injury and neurobehavioral disorders in affected children. Innate immunity, specifically Toll-like receptor (TLR) signaling pathways are present throughout the reproductive tract as well as in the placenta, fetal membranes, and fetus. The TLR pathways are mechanistically involved in host responses to foreign pathogens and may lead to brain injury associated with prenatal inflammation. Objective: We aimed to determine whether the activation of the TLR4 signaling pathway, in the mother and fetus, is critical to fetal brain injury in the setting of intrauterine inflammation. Methods: A mini-laparotomy was performed on time pregnant C57B6 mice and 2 knockout mouse strains lacking the function of the Tlr4 and Myd88 genes on embryonic day 15. Intrauterine injections of Escherichia coli lipopolysaccharide or saline were administered as described previously. Dams were killed 6 hours postsurgery, and placental, amniotic fluid, and fetal brain tissue were collected. To assess brain injury, quantitative polymerase chain reaction (qPCR) analysis was performed on multiple components of the NOTCH signaling pathway, including Hes genes. Interleukin (IL) IL6, IL1β, and CCL5 expression was assessed using qPCR and enzyme-linked immunosorbent assay. Results: Using an established mouse model of intrauterine inflammation, we demonstrate that the abrogation of TLR4 signaling eliminates the cytokine response in mother and fetus and prevents brain injury associated with increased expression of transcriptional effectors of the NOTCH signaling pathway, Hes1 and Hes5. Conclusions: These data show that the activation of the TLR4 signaling pathway is necessary for the development of fetal brain injury in response to intrauterine inflammation.

Roles of GABA Signaling in Directing Basket Cell Axonal Projections Toward Purkinje Cells in the Cerebellum

2020 ◽  
Author(s):  
Hideki Miwa ◽  
Ken Kobayashi ◽  
Shinobu Hirai ◽  
Mitsuhiko Yamada ◽  
Masahiko Watanabe ◽  
...  
Keyword(s):  
Purkinje Cells ◽  
Motor Coordination ◽  
Basket Cell ◽  
K Channel ◽  
Mouse Strains ◽  
Gamma Aminobutyric Acid ◽  
Knock Out ◽  
Inhibitory Neurotransmitter ◽  
Basket Cells ◽  
Gaba Signaling

Abstract Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system, synthesized by two isoforms of glutamate decarboxylase (GAD): GAD65 and GAD67. GABA may act as a trophic factor during brain development, but its contribution to the development and maturation of cerebellar neural circuits is not known. To understand the roles of GABA in cerebellar development and associated functions in motor coordination and balance, we examined GAD65 conventional knock out (KO) mice and mice in which GAD67 was eliminated in parvalbumin-expressing neurons ( PV-Cre ; GAD67 flox/flox mice). We found aberrant subcellular localization of the Shaker-type K channel Kv1.1 in basket cell collaterals of PV-Cre ; GAD67 flox/flox mice and abnormal projections from basket cells to Purkinje cells in both mouse strains. Furthermore, PV-Cre ; GAD67 flox/flox mice exhibited abnormal motor coordination in the rotarod test. These results indicate that GABA signaling in the cerebellum during development is critical for establishing appropriate connections between basket cells and Purkinje cells and is associated with motor coordination in mice.

scholarly journals Differential attenuation of β2 integrin–dependent and –independent neutrophil migration by Ly6G ligation

2019 ◽  
Vol 3 (3) ◽  
pp. 256-267 ◽  
Author(s):  
Pierre Cunin ◽  
Pui Y. Lee ◽  
Edy Kim ◽  
Angela B. Schmider ◽  
Nathalie Cloutier ◽  
...  
Keyword(s):  
Interleukin 1 ◽  
Neutrophil Migration ◽  
Surface Protein ◽  
Joint Inflammation ◽  
Selective Inhibition ◽  
Β2 Integrin ◽  
Β2 Integrins ◽  
Neutrophil Surface

Abstract Antibody ligation of the murine neutrophil surface protein Ly6G disrupts neutrophil migration in some contexts but not others. We tested whether this variability reflected divergent dependence of neutrophil migration on β2 integrins, adhesion molecules that interact with Ly6G at the neutrophil surface. In integrin-dependent murine arthritis, Ly6G ligation attenuated joint inflammation, even though mice lacking Ly6G altogether developed arthritis normally. By contrast, Ly6G ligation had no impact on integrin-independent neutrophil migration into inflamed lung. In peritoneum, the role of β2 integrins varied with stimulus, proving dispensable for neutrophil entry in Escherichia coli peritonitis but contributory in interleukin 1 (IL-1)–mediated sterile peritonitis. Correspondingly, Ly6G ligation attenuated only IL-1 peritonitis, disrupting the molecular association between integrins and Ly6G and inducing cell-intrinsic blockade restricted to integrin-dependent migration. Consistent with this observation, Ly6G ligation impaired integrin-mediated postadhesion strengthening for neutrophils arresting on activated cremaster endothelium in vivo. Together, these findings identify selective inhibition of integrin-mediated neutrophil emigration through Ly6G ligation, highlighting the marked site and stimulus specificity of β2 integrin dependence in neutrophil migration.

Neutrophil activation via β2 integrins (CD11/CD18): Molecular mechanisms and clinical implications

2007 ◽  
Vol 98 (08) ◽  
pp. 262-273 ◽  
Author(s):  
Jürgen Schymeinsky ◽  
Attila Mócsai ◽  
Barbara Walzog
Keyword(s):  
Receptor Tyrosine Kinase ◽  
Acute Inflammation ◽  
Molecular Mechanisms ◽  
Inflammatory Diseases ◽  
Polymorphonuclear Neutrophils ◽  
Downstream Signaling ◽  
Β2 Integrin ◽  
Pmn Functions ◽  
Integrin Family ◽  
Β2 Integrins

SummaryPolymorphonuclear neutrophils (PMN) are key components of the innate immunity and their efficient recruitment to the sites of lesion is a prerequisite for acute inflammation. Signaling via adhesion molecules of the β2 integrin family (CD11/CD18) plays an essential role for PMN recruitment and activation during inflammation. In this review, we will focus on the non-receptor tyrosine kinase Syk, an important downstream signaling component of β2 integrins that is required for the control of different PMN functions including adhesion,migration and phagocytosis. The exploration of β2 integrin-mediated Syk activation provided not only novel insights into the control of PMN functions but also led to the identification of Syk as a new molecular target for therapeutic intervention during inflammatory diseases.

Factor IX: Insights from knock-out and genetically engineered mice

2008 ◽  
Vol 100 (10) ◽  
pp. 563-575 ◽  
Author(s):  
Paul E. Monahan
Keyword(s):  
Mouse Models ◽  
Positional Cloning ◽  
Coagulation Factors ◽  
Genetically Engineered ◽  
Factor Ix ◽  
Mouse Strains ◽  
Knock Out ◽  
Haemophilia B ◽  
Genetically Engineered Mice ◽  
Knock Out Mice

SummaryThe study of coagulation factors has been rapidly advanced by studies performed in genetically engineered mouse strains. Investigation of factor IX (FIX) has benefited from excellent genedeleted mouse models that recapitulate many of the features of human haemophilia B. Moreover, advanced positional cloning techniques and availability of technology to allow not only knock-out mice, but also knock-in and knock-down mice, provide new opportunities to observe genotype-phenotype and structure-function correlations regarding FIX, as well as the interaction of FIX with inflammatory, immune, and tissue repair systems. In this paper, available FIX knock-out mice and additional haemophilia B mouse models are reviewed specifically in regards to observations these models have facilitated concerning: factor IX gene expression and factor IX protein pharmacokinetics; the role of FIX in haemostasis, thrombosis and wound healing; insights into coagulation FIX arising out of gene therapy applications in haemophilia mouse models; immunology of tolerance or loss of tolerance of FIX and inhibitor antibody formation.

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