scholarly journals Neisseria meningitidis Induces Pathology-Associated Cellular and Molecular Changes in Trigeminal Schwann Cells

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Ali Delbaz ◽  
Mo Chen ◽  
Freda E.-C. Jen ◽  
Benjamin L. Schulz ◽  
Alain-Dominique Gorse ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Schwann Cells ◽  
Glial Cells ◽  
Trigeminal Nerve ◽  
Three Dimensional ◽  
Cns Infection ◽  
Intercellular Signaling ◽  
Cellular Mechanisms ◽  
Content Type

ABSTRACT Neisseria meningitidis, a common cause of sepsis and bacterial meningitis, infects the meninges and central nervous system (CNS), primarily via paracellular traversal across the blood-brain barrier (BBB) or blood-cerebrospinal fluid barrier. N. meningitidis is often present asymptomatically in the nasopharynx, and the nerves extending between the nasal cavity and the brain constitute an alternative route by which the meningococci may reach the CNS. To date, the cellular mechanisms involved in nerve infection are not fully understood. Peripheral nerve glial cells are phagocytic and are capable of eliminating microorganisms, but some pathogens may be able to overcome this protection mechanism and instead infect the glia, causing cell death or pathology. Here, we show that N. meningitidis readily infects trigeminal Schwann cells (the glial cells of the trigeminal nerve) in vitro in both two-dimensional and three-dimensional cell cultures. Infection of trigeminal Schwann cells may be one mechanism by which N. meningitidis is able to invade the CNS. Infection of the cells led to multinucleation and the appearance of atypical nuclei, with the presence of horseshoe nuclei and the budding of nuclei increasing over time. Using sequential window acquisition of all theoretical mass spectra (SWATH-MS) proteomics followed by bioinformatics pathway analysis, we showed that N. meningitidis induced protein alterations in the glia that were associated with altered intercellular signaling, cell-cell interactions, and cellular movement. The analysis also suggested that the alterations in protein levels were consistent with changes occurring in cancer. Thus, infection of the trigeminal nerve by N. meningitidis may have ongoing adverse effects on the biology of Schwann cells, which may lead to pathology.

scholarly journals Three-Dimensional Observations of an Aperiodic Oscillatory Gliding Behavior in Myxococcus xanthus Using Confocal Interference Reflection Microscopy

mSphere ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Liam M. Rooney ◽  
Lisa S. Kölln ◽  
Ross Scrimgeour ◽  
William B. Amos ◽  
Paul A. Hoskisson ◽  
...  
Keyword(s):  
Myxococcus Xanthus ◽  
Three Dimensional ◽  
Oscillatory Behavior ◽  
Gliding Motility ◽  
Bacterial Cells ◽  
Force Transmission ◽  
Content Type ◽  
Gliding Bacteria ◽  
Microscopy Techniques

ABSTRACT The deltaproteobacterium Myxococcus xanthus is a model for bacterial motility and has provided unprecedented insights into bacterial swarming behaviors. Fluorescence microscopy techniques have been invaluable in defining the mechanisms that are involved in gliding motility, but these have almost entirely been limited to two-dimensional (2D) studies, and there is currently no understanding of gliding motility in a three-dimensional (3D) context. We present here the first use of confocal interference reflection microscopy (IRM) to study gliding bacteria, revealing aperiodic oscillatory behavior with changes in the position of the basal membrane relative to the substrate on the order of 90 nm in vitro. First, we use a model planoconvex lens specimen to show how topological information can be obtained from the wavelength-dependent interference pattern in IRM. We then use IRM to observe gliding M. xanthus bacteria and show that cells undergo previously unobserved changes in their adhesion profile as they glide. We compare the wild type with mutants that have reduced motility, which also exhibit the same changes in the adhesion profile during gliding. We find that the general gliding behavior is independent of the proton motive force-generating complex AglRQS and suggest that the novel behavior that we present here may be a result of recoil and force transmission along the length of the cell body following firing of the type IV pili. IMPORTANCE 3D imaging of live bacteria with optical microscopy techniques is a challenge due to the small size of bacterial cells, meaning that previous studies have been limited to observing motility behavior in 2D. We introduce the application of confocal multiwavelength interference reflection microscopy to bacteria, which enables visualization of 3D motility behaviors in a single 2D image. Using the model organism Myxococcus xanthus, we identified novel motility behaviors that are not explained by current motility models, where gliding bacteria exhibit aperiodic changes in their adhesion to an underlying solid surface. We concluded that the 3D behavior was not linked to canonical motility mechanisms and that IRM could be applied to study a range of microbiological specimens with minimal adaptation to a commercial microscope.

scholarly journals Three-Dimensional In Vitro Staphylococcus aureus Abscess Communities Display Antibiotic Tolerance and Protection from Neutrophil Clearance

2020 ◽  
Vol 88 (11) ◽  
Author(s):  
Marloes I. Hofstee ◽  
Martijn Riool ◽  
Igors Terjajevs ◽  
Keith Thompson ◽  
Martin J. Stoddart ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Cells ◽  
Early Stage ◽  
Three Dimensional ◽  
Collagen Gel ◽  
Maximum Size ◽  
Human Neutrophils ◽  
Content Type

ABSTRACT Staphylococcus aureus is a prominent human pathogen in bone and soft-tissue infections. Pathophysiology involves abscess formation, which consists of central staphylococcal abscess communities (SACs), surrounded by a fibrin pseudocapsule and infiltrating immune cells. Protection against the ingress of immune cells such as neutrophils, or tolerance to antibiotics, remains largely unknown for SACs and is limited by the lack of availability of in vitro models. We describe a three-dimensional in vitro model of SACs grown in a human plasma-supplemented collagen gel. The in vitro SACs reached their maximum size by 24 h and elaborated a fibrin pseudocapsule, as confirmed by electron and immunofluorescence microscopy. The in vitro SACs tolerated 100× the MIC of gentamicin alone and in combination with rifampin, while planktonic controls and mechanically dispersed SACs were efficiently killed. To simulate a host response, SACs were exposed to differentiated PLB-985 neutrophil-like (dPLB) cells and to primary human neutrophils at an early stage of SAC formation or after maturation at 24 h. Both cell types were unable to clear mature in vitro SACs, but dPLB cells prevented SAC growth upon early exposure before pseudocapsule maturation. Neutrophil exposure after plasmin pretreatment of the SACs resulted in a significant decrease in the number of bacteria within the SACs. The in vitro SAC model mimics key in vivo features, offers a new tool to study host-pathogen interactions and drug efficacy assessment, and has revealed the functionality of the S. aureus pseudocapsule in protecting the bacteria from host phagocytic responses and antibiotics.

Producing Neurospheroids and Hydrogels to Create a Three-dimensional in Vitro Model for the Use of Conduits in Peripheral Nerve Regeneration

Neurosurgery ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. E272-E272
Author(s):  
Devyani Shete ◽  
Aran Batth ◽  
Aditi Nijhawan ◽  
Jaffer Choudhary ◽  
Ian Thompson
Keyword(s):  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Schwann Cells ◽  
Peripheral Nerve Regeneration ◽  
3D Structure ◽  
Three Dimensional ◽  
Negative Control ◽  
Cellular Growth ◽  
Live Cells

Abstract INTRODUCTION Peripheral nerve regeneration is a complex challenge that requires suitable nerve guidance systems to bridge the severed ends of 2 nerves back together. Current polymeric conduits on the market provide good cellular growth but are limited by the length of gap defect they can repair, and complete functional recovery is rare. This project focused on creating a three-dimensional (3D) in Vitro spheroidal sprouting assay for peripheral nerve regeneration, as well as producing and testing different polymeric hydrogels as potential scaffold materials for the conduit. METHODS Different concentrations of chitosan, methylcellulose (MC) and sodium alginate were produced, as well as blends of these materials. These hydrogels were seeded with 3D neurospheroids, along with NG108-15 (neuronal) cells and Schwann cells to test their biocompatibility. RESULTS MTT assays showed the mean absorbance of chitosan gels with NG108-15 cells at 24 hr (P < .001) and 72 hr (P > .05) was similar/slightly higher than the negative control. Live-Dead data showed 93.4% of live cells at DIV7 on MC: Ch blends, compared to 72% with chitosan alone. CONCLUSION Overall, both chitosan and MC were nontoxic and biocompatible with NG108-15 and Schwann cells. Blending chitosan with MC improved its chemical and physical properties. The cells formed spheroids that well on a gel; this pseudo-3D structure is excellent for research purposes compared to 2D as it mimics the body's internal environment.

scholarly journals Membrane Protein Complex ExbB4-ExbD1-TonB1from Escherichia coli Demonstrates Conformational Plasticity

2015 ◽  
Vol 197 (11) ◽  
pp. 1873-1885 ◽  
Author(s):  
Aleksandr Sverzhinsky ◽  
Jacqueline W. Chung ◽  
Justin C. Deme ◽  
Lucien Fabre ◽  
Kristian T. Levey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Iron Acquisition ◽  
Proton Translocation ◽  
Three Dimensional ◽  
Structural Data ◽  
Structural Features ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type

ABSTRACTIron acquisition at the outer membrane (OM) of Gram-negative bacteria is powered by the proton motive force (PMF) of the cytoplasmic membrane (CM), harnessed by the CM-embedded complex of ExbB, ExbD, and TonB. Its stoichiometry, ensemble structural features, and mechanism of action are unknown. By panning combinatorial phage libraries, periplasmic regions of dimerization between ExbD and TonB were predicted. Using overexpression of full-length His6-taggedexbB-exbDand S-taggedtonB, we purified detergent-solubilized complexes of ExbB-ExbD-TonB fromEscherichia coli. Protein-detergent complexes of ∼230 kDa with a hydrodynamic radius of ∼6.0 nm were similar to previously purified ExbB4-ExbD2complexes. Significantly, they differed in electronegativity by native agarose gel electrophoresis. The stoichiometry was determined to be ExbB4-ExbD1-TonB1. Single-particle electron microscopy agrees with this stoichiometry. Two-dimensional averaging supported the phage display predictions, showing two forms of ExbD-TonB periplasmic heterodimerization: extensive and distal. Three-dimensional (3D) particle classification showed three representative conformations of ExbB4-ExbD1-TonB1. Based on our structural data, we propose a model in which ExbD shuttles a proton across the CM via an ExbB interprotein rearrangement. Proton translocation would be coupled to ExbD-mediated collapse of extended TonB in complex with ligand-loaded receptors in the OM, followed by repositioning of TonB through extensive dimerization with ExbD. Here we present the first report for purification of the ExbB-ExbD-TonB complex, molar ratios within the complex (4:1:1), and structural biology that provides insights into 3D organization.IMPORTANCEReceptors in the OM of Gram-negative bacteria allow entry of iron-bound siderophores that are necessary for pathogenicity. Numerous iron-acquisition strategies rely upon a ubiquitous and unique protein for energization: TonB. Complexed with ExbB and ExbD, the Ton system links the PMF to OM transport. Blocking iron uptake by targeting a vital nanomachine holds promise in therapeutics. Despite much research, the stoichiometry, structural arrangement, and molecular mechanism of the CM-embedded ExbB-ExbD-TonB complex remain unreported. Here we demonstratein vitroevidence of ExbB4-ExbD1-TonB1complexes. Using 3D EM, we reconstructed the complex in three conformational states that show variable ExbD-TonB heterodimerization. Our structural observations form the basis of a model for TonB-mediated iron acquisition.

scholarly journals Interactions between the Lipoprotein PilP and the Secretin PilQ in Neisseria meningitidis

2007 ◽  
Vol 189 (15) ◽  
pp. 5716-5727 ◽  
Author(s):  
Seetha V. Balasingham ◽  
Richard F. Collins ◽  
Reza Assalkhou ◽  
Håvard Homberset ◽  
Stephan A. Frye ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Specific Interaction ◽  
Three Dimensional ◽  
Middle Part ◽  
Dna Uptake ◽  
Type Iv ◽  
Pilus Biogenesis ◽  
Inner Membrane Protein ◽  
Mutant Phenotypes

ABSTRACT Neisseria meningitidis can be the causative agent of meningitis or septicemia. This bacterium expresses type IV pili, which mediate a variety of functions, including autoagglutination, twitching motility, biofilm formation, adherence, and DNA uptake during transformation. The secretin PilQ supports type IV pilus extrusion and retraction, but it also requires auxiliary proteins for its assembly and localization in the outer membrane. Here we have studied the physical properties of the lipoprotein PilP and examined its interaction with PilQ. We found that PilP was an inner membrane protein required for pilus expression and transformation, since pilP mutants were nonpiliated and noncompetent. These mutant phenotypes were restored by the expression of PilP in trans. The pilP gene is located upstream of pilQ, and analysis of their transcripts indicated that pilP and pilQ were cotranscribed. Furthermore, analysis of the level of PilQ expression in pilP mutants revealed greatly reduced amounts of PilQ only in the deletion mutant, exhibiting a polar effect on pilQ transcription. In vitro experiments using recombinant fragments of PilP and PilQ showed that the N-terminal region of PilP interacted with the middle part of the PilQ polypeptide. A three-dimensional reconstruction of the PilQ-PilP interacting complex was obtained at low resolution by transmission electron microscopy, and PilP was shown to localize around the cap region of the PilQ oligomer. These findings suggest a role for PilP in pilus biogenesis. Although PilQ does not need PilP for its stabilization or membrane localization, the specific interaction between these two proteins suggests that they might have another coordinated activity in pilus extrusion/retraction or related functions.

scholarly journals Migratory Activation of Primary Cortical Microglia upon Infection with Toxoplasma gondii

2011 ◽  
Vol 79 (8) ◽  
pp. 3046-3052 ◽  
Author(s):  
Isabel Dellacasa-Lindberg ◽  
Jonas M. Fuks ◽  
Romanico B. G. Arrighi ◽  
Henrik Lambert ◽  
Robert P. A. Wallin ◽  
...  
Keyword(s):  
T Cells ◽  
Toxoplasma Gondii ◽  
Mhc Class Ii ◽  
Glial Cells ◽  
Costimulatory Molecule ◽  
Toxoplasmic Encephalitis ◽  
Immune Functions ◽  
Content Type

ABSTRACTDisseminated toxoplasmosis in the central nervous system (CNS) is often accompanied by a lethal outcome. Studies with murine models of infection have focused on the role of systemic immunity in control of toxoplasmic encephalitis, while knowledge remains limited on the contributions of resident cells with immune functions in the CNS. In this study, the role of glial cells was addressed in the setting of recrudescentToxoplasmainfection in mice. Activated astrocytes and microglia were observed in the close vicinity of foci with replicating parasitesin situin the brain parenchyma.Toxoplasma gondiitachyzoites were allowed to infect primary microglia and astrocytesin vitro. Microglia were permissive to parasite replication, and infected microglia readily transmigrated across transwell membranes and cell monolayers. Thus, infected microglia, but not astrocytes, exhibited a hypermotility phenotype reminiscent of that recently described for infected dendritic cells. In contrast to gamma interferon-activated microglia,Toxoplasma-infected microglia did not upregulate major histocompatibility complex (MHC) class II molecules and the costimulatory molecule CD86. YetToxoplasma-infected microglia and astrocytes exhibited increased sensitivity to T cell-mediated killing, leading to rapid parasite transfer to effector T cellsin vitro. We hypothesize that glial cells and T cells, besides their role in triggering antiparasite immunity, may also act as “Trojan horses,” paradoxically facilitating dissemination ofToxoplasmawithin the CNS. To our knowledge, this constitutes the first report of migratory activation of a resident CNS cell by an intracellular parasite.

scholarly journals Disease-Associated Neisseria meningitidis Isolates Inhibit Wound Repair in Respiratory Epithelial Cells in a Type IV Pilus-Independent Manner

2014 ◽  
Vol 82 (12) ◽  
pp. 5023-5034 ◽  
Author(s):  
Xiaoyun Ren ◽  
Joanna K. MacKichan
Keyword(s):  
Cell Migration ◽  
Neisseria Meningitidis ◽  
Meningococcal Disease ◽  
Wound Repair ◽  
Disease Onset ◽  
Independent Manner ◽  
Content Type ◽  
Type Iv ◽  
Respiratory Epithelial

ABSTRACTNeisseria meningitidisis the causative agent of meningococcal disease. Onset of meningococcal disease can be extremely rapid and can kill within a matter of hours. However, although a much-feared pathogen,Neisseria meningitidisis frequently found in the nasopharyngeal mucosae of healthy carriers. The bacterial factors that distinguish disease- from carriage-associated meningococci are incompletely understood. Evidence suggesting that disruptions to the nasopharynx may increase the risk of acquiring meningococcal disease led us to evaluate the ability of disease- and carriage-associated meningococcal isolates to inhibit cell migration, using anin vitroassay for wound repair. We found that disease-associated isolates in our collection inhibited wound closure, while carriage-associated isolates were more variable, with many isolates not inhibiting wound repair at all. For isolates selected for further study, we found that actin morphology, such as presence of lamellipodia, correlated with cell migration. We demonstrated that multiple meningococcal virulence factors, including the type IV pili, are dispensable for inhibition of wound repair. Inhibition of wound repair was also shown to be an active process, i.e., requiring live bacteria undergoing active protein synthesis.

scholarly journals Induced Pluripotency: A Powerful Tool for In Vitro Modeling

2020 ◽  
Vol 21 (23) ◽  
pp. 8910 ◽  
Author(s):  
Romana Zahumenska ◽  
Vladimir Nosal ◽  
Marek Smolar ◽  
Terezia Okajcekova ◽  
Henrieta Skovierova ◽  
...  
Keyword(s):  
Drug Testing ◽  
Disease Modeling ◽  
Three Dimensional ◽  
Induced Pluripotent Stem Cell ◽  
Cellular Mechanisms ◽  
Major Health ◽  
Induced Pluripotency ◽  
Developmental Capacity ◽  
Induced Pluripotent

One of the greatest breakthroughs of regenerative medicine in this century was the discovery of induced pluripotent stem cell (iPSC) technology in 2006 by Shinya Yamanaka. iPSCs originate from terminally differentiated somatic cells that have newly acquired the developmental capacity of self-renewal and differentiation into any cells of three germ layers. Before iPSCs can be used routinely in clinical practice, their efficacy and safety need to be rigorously tested; however, iPSCs have already become effective and fully-fledged tools for application under in vitro conditions. They are currently routinely used for disease modeling, preparation of difficult-to-access cell lines, monitoring of cellular mechanisms in micro- or macroscopic scales, drug testing and screening, genetic engineering, and many other applications. This review is a brief summary of the reprogramming process and subsequent differentiation and culture of reprogrammed cells into neural precursor cells (NPCs) in two-dimensional (2D) and three-dimensional (3D) conditions. NPCs can be used as biomedical models for neurodegenerative diseases (NDs), which are currently considered to be one of the major health problems in the human population.

scholarly journals Inactivation of NMB0419, Encoding a Sel1-Like Repeat (SLR) Protein, in Neisseria meningitidis Is Associated with Differential Expression of Genes Belonging to the Fur Regulon and Reduced Intraepithelial Replication

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Ming-Shi Li ◽  
Paul R. Langford ◽  
J. Simon Kroll
Keyword(s):  
Epithelial Cells ◽  
Neisseria Meningitidis ◽  
Iron Acquisition ◽  
Regulatory Function ◽  
Growth Defect ◽  
Wild Type ◽  
Content Type ◽  
Expression Of Genes ◽  
New Perspective

ABSTRACT Neisseria meningitidis is a commensal microbe that colonizes the human nasopharynx but occasionally invades the bloodstream to cause life-threatening infection. N. meningitidis MC58 NMB0419 encodes a Sel1-like repeat (SLR)-containing protein, previously implicated in invasion of epithelial cells. A gene-regulatory function was revealed in Escherichia coli expressing plasmid-borne NMB0419 and showing significantly increased epithelial adherence compared to the wild type, due to increased expression of mannose-sensitive type 1 pili. While a meningococcal NMB0419 mutant did not have altered epithelial adherence, in a transcriptome-wide comparison of the wild type and an NMB0419 mutant, a large proportion of genes differentially regulated in the mutant were involved in iron acquisition and metabolism. Fifty-one percent and 38% of genes, respectively, up- and downregulated in the NMB0419 mutant had previously been identified as being induced and repressed by meningococcal Fur. An in vitro growth defect of the NMB0419 mutant under iron restriction was consistent with the downregulation of tbpAB and hmbR, while an intraepithelial replication defect was consistent with the downregulation of tonB, exbB, and exbD, based on a known phenotype of a meningococcal tonB mutant. Disruption of the N-terminal NMB0419 signal peptide, predicted to export the protein beyond the cytoplasmic membrane, resulted in loss of functional traits in N. meningitidis and E. coli. Our study indicates that the expression of NMB0419 is associated with transcriptional changes counterbalancing the regulatory function of Fur, offering a new perspective on regulatory mechanisms involved in meningococcal interaction with epithelial cells, and suggests new insights into the roles of SLR-containing genes in other bacteria.

scholarly journals Lactobacilli Antagonize the Growth, Motility, and Adherence of Brachyspira pilosicoli: a Potential Intervention against Avian Intestinal Spirochetosis

2011 ◽  
Vol 77 (15) ◽  
pp. 5402-5411 ◽  
Author(s):  
Luke J. Mappley ◽  
Monika A. Tchórzewska ◽  
William A. Cooley ◽  
Martin J. Woodward ◽  
Roberto M. La Ragione
Keyword(s):  
Lactobacillus Reuteri ◽  
Control Strategies ◽  
Three Dimensional ◽  
Dependent Manner ◽  
Growth Promoters ◽  
Electron Microscopic ◽  
Content Type ◽  
Brachyspira Pilosicoli ◽  
Intestinal Spirochetosis

ABSTRACTAvian intestinal spirochetosis (AIS) results from the colonization of the ceca and colorectum of poultry by pathogenicBrachyspiraspecies. The number of cases of AIS has increased since the 2006 European Union ban on the use of antibiotic growth promoters, which, together with emerging antimicrobial resistance inBrachyspira, has driven renewed interest in alternative intervention strategies. Probiotics have been reported as protecting livestock against infection with common enteric pathogens, and here we investigate which aspects of the biology ofBrachyspirathey antagonize in order to identify possible interventions against AIS. The cell-free supernatants (CFS) of twoLactobacillusstrains,Lactobacillus reuteriLM1 andLactobacillus salivariusLM2, suppressed the growth ofBrachyspira pilosicoliB2904 in a pH-dependent manner. Inin vitroadherence and invasion assays with HT29-16E three-dimensional (3D) cells and in a novel avian cecalin vitroorgan culture (IVOC) model, the adherence and invasion ofB. pilosicoliin epithelial cells were reduced significantly by the presence of lactobacilli (P< 0.001). In addition, live and heat-inactivated lactobacilli inhibited the motility ofB. pilosicoli, and electron microscopic observations indicated that contact between the lactobacilli andBrachyspirawas crucial in inhibiting both adherence and motility. These data suggest that motility is essential forB. pilosicolito adhere to and invade the gut epithelium and that any interference of motility may be a useful tool for the development of control strategies.

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