scholarly journals In situ expression and localization of Neisseria gonorrhoeae opacity proteins in infected epithelial cells: apparent role of Opa proteins in cellular invasion.

1991 ◽  
Vol 173 (6) ◽  
pp. 1395-1405 ◽  
Author(s):  
J F Weel ◽  
C T Hopman ◽  
J P van Putten
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Natural Infection ◽  
Phase Variation ◽  
Functional Adaptation ◽  
Host Cells ◽  
Bacterial Invasion ◽  
Rapid Phase ◽  
Immunomorphological Study ◽  
Opacity Proteins

During natural infection, gonococcal opacity proteins (Opa) undergo rapid phase variation, but how this phenomenon contributes to the virulence of the bacteria is not well understood. In the present immunomorphological study we examined the actual Opa status of individual gonococci during various stages of gonococcal infection of Chang epithelial cells, by probing ultrathin sections of infected specimens with Opa-specific monoclonal antibodies. Our results demonstrate a heterogeneous Opa expression during the initial interaction of the bacteria, but an almost 100% expression of one of the probed Opas during their secondary attachment and entry into the host cells, suggesting a role for distinct Opas in cellular penetration. The association between Opa expression, tight attachment, and bacterial invasion into the host cells could be confirmed with isogenic variants that expressed different Opa proteins. Once inside the epithelial cells, both morphologically intact, Opa positive and morphologically disintegrated, Opa negative bacteria were observed. The loss of Opa immunoreactivity in intracellular gonococci could not be related to the presence of a particular Opa protein, but could be mimicked by incubating the organisms with extracts of sonicated uninfected epithelial cells, suggesting that it was caused by host cell proteolytic activity. Taken together, our data suggest that Opa phase transitions confer a functional adaptation of the bacteria enabling host cell penetration.

scholarly journals Models of Invasion of Enteric and Periodontal Pathogens Into Epithelial Cells: A Comparative Analysis

1997 ◽  
Vol 8 (4) ◽  
pp. 389-409 ◽  
Author(s):  
D.H. Meyer ◽  
K.P. Mintz ◽  
P.M. Fives-Taylor
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Cell Function ◽  
Shigella Flexneri ◽  
Host Cells ◽  
Bacterial Invasion ◽  
Periodontal Pathogens ◽  
Chronic Infections ◽  
Enteropathogenic Bacteria ◽  
Bacteroides Gingivalis

Bacterial invasion of epithelial cells is associated with the initiation of infection by many bacteria. To carry out this action, bacteria have developed remarkable processes and mechanisms that co-opt host cell function and stimulate their own uptake and adaptation to the environment of the host cell. Two general types of invasion processes have been observed. In one type, the pathogens (e.g., Salmonella and Yersinia spp.) remain in the vacuole in which they are internalized and replicate within the vacuole. In the other type, the organism (e.g., Actinobacillus actinomycetemcomitans, Shigella flexneri, and Listeria monocytogenes) is able to escape from the vacuole, replicate in the host cell cytoplasm, and spread to adjacent host cells. The much-studied enteropathogenic bacteria usurp primarily host cell microfilaments for entry. Those organisms which can escape from the vacuole do so by means of hemolytic factors and C type phospholipases. The cell-to-cell spread of these organisms is mediated by microfilaments. The investigation of invasion by periodontopathogens is in its infancy in comparison with that of the enteric pathogens However, studies to date on two invasive periodontopathogens, A. actinomycetemcomitans and Porphyromonas (Bacteroides) gingivalis, reveal that these bacteria have developed invasion strategies and mechanisms similar to those of the enteropathogens. Entry of A. actinomycetemcomitans is mediated by microfilaments, whereas entry of P. gingivalis is mediated by both microfilaments and microtubules. A. actinomycetemcomitans, like Shigella and Listeria, can escape from the vacuole and spread to adjacent cells. However, the spread of A. actinomycetemcomitans is linked to host cell microtubules, not microfilaments. The paradigms presented establish that bacteria which cause chronic infections, such as periodontitis, and bacteria which cause acute diseases, such as dysentery, have developed similar invasion strategies.

scholarly journals Bacterial entry and intracellular processing of Neisseria gonorrhoeae in epithelial cells: immunomorphological evidence for alterations in the major outer membrane protein P.IB.

1991 ◽  
Vol 174 (3) ◽  
pp. 705-715 ◽  
Author(s):  
J F Weel ◽  
C T Hopman ◽  
J P van Putten
Keyword(s):  
Epithelial Cells ◽  
Membrane Protein ◽  
Host Cell ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
Host Cells ◽  
Eukaryotic Cells ◽  
Bacterial Invasion ◽  
Intracellular Processing

The fate of the major outer membrane protein of the gonococcus, P.IB, during the adherence, entry, and intracellular processing of the bacteria in infected epithelial cells was investigated using post-embedding immunoelectron microscopy. Various domains of the P.IB molecule were probed at different stages in the infection. These studies revealed that P.IB epitope exposure remained unaltered during the initial attachment of the bacteria to the host cells. In contrast, upon secondary attachment of the bacteria to the eukaryotic cells, apparent zones of adhesion were formed between the gonococci and the host cell membrane, which were characterized by loss of a defined P.IB epitope. These zones of adhesion with the altered P.IB immunoreactivity continued to exist and increased in number during cellular penetration, suggesting that they were essential to bacterial invasion into the eukaryotic cells. After bacterial entry, two classes of gonococci could be recognized; morphologically intact, P.IB-positive bacteria and disintegrated organisms that showed a change in, and, in a later stage, a complete loss of P.IB immunoreactivity. The intracellular alterations in the P.IB antigen could be prevented by treatment of the host cells with the lysosomotropic agent chloroquine. These observations point to a mechanism by which a subpopulation of intracellular gonococci can escape the epithelial cell defense by preventing or resisting exposure to host cell proteolytic activity.

Interactions Between Salmonella Typhimurium, Enteropathogenic Escherichia Coli (EPEC), and Host Epithelial Cells

1995 ◽  
Vol 9 (1) ◽  
pp. 31-36 ◽  
Author(s):  
B.B. Finlay
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Salmonella Typhimurium ◽  
Host Cell ◽  
Inositol Phosphate ◽  
Enteric Pathogens ◽  
Host Protein ◽  
Host Cells ◽  
Enteropathogenic Escherichia Coli ◽  
Sequence Of Events

The interactions that occur between pathogenic micro-organisms and their host cells are complex and intimate. We have used two enteric pathogens, Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC), to examine the interactions that occur between these organisms and epithelial cells. Although these are enteric pathogens, the knowledge and techniques developed from these systems may be applied to the study of dental pathogens. Both S. typhimurium and EPEC disrupt epithelial monolayer integrity, although by different mechanisms. Both pathogens cause loss of microvilli and re-arrangement of the underlying host cytoskeleton. Despite these similarities, both organisms send different signals into the host cell. EPEC signal transduction involves generation of intracellular calcium and inositol phosphate fluxes, and activation of host tyrosine kinases that results in tyrosine phosphorylation of a 90-kDa host protein. Bacterial mutants have been identifed that are deficient in signaling to the host. We propose a sequence of events that occur when EPEC interacts with epithelial cells. Once inside a host cell, S. typhimurium remains within a vacuole. To define some of the parameters of the intracellular environment, we constructed genetic fusions of known genes with lacZ, and used these fusions as reporter probes of the intracellular vacuolar environment. We have also begun to examine the bacterial and host cell factors necessary for S. typhimurium to multiply within epithelial cells. We found that this organism triggers the formation of novel tubular lysosomes, and these structures are linked with intracellular replication.

scholarly journals Suppression of influenza A virus replication in human lung epithelial cells by noncytotoxic concentrations bafilomycin A1

2015 ◽  
Vol 308 (3) ◽  
pp. L270-L286 ◽  
Author(s):  
Behzad Yeganeh ◽  
Saeid Ghavami ◽  
Andrea L. Kroeker ◽  
Thomas H. Mahood ◽  
Gerald L. Stelmack ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Influenza A Virus ◽  
Influenza A ◽  
Life Cycles ◽  
Host Cells ◽  
Nuclear Accumulation ◽  
Low Concentration ◽  
High Concentrations ◽  
The Impact

Subcellular trafficking within host cells plays a critical role in viral life cycles, including influenza A virus (IAV). Thus targeting relevant subcellular compartments holds promise for effective intervention to control the impact of influenza infection. Bafilomycin A1(Baf-A1), when used at relative high concentrations (≥10 nM), inhibits vacuolar ATPase (V-ATPase) and reduces endosome acidification and lysosome number, thus inhibiting IAV replication but promoting host cell cytotoxicity. We tested the hypothesis that much lower doses of Baf-A1also have anti-IAV activity, but without toxic effects. Thus we assessed the antiviral activity of Baf-A1at different concentrations (0.1–100 nM) in human alveolar epithelial cells (A549) infected with IAV strain A/PR/8/34 virus (H1N1). Infected and mock-infected cells pre- and cotreated with Baf-A1were harvested 0–24 h postinfection and analyzed by immunoblotting, immunofluorescence, and confocal and electron microscopy. We found that Baf-A1had disparate concentration-dependent effects on subcellular organelles and suppressed affected IAV replication. At concentrations ≥10 nM Baf-A1inhibited acid lysosome formation, which resulted in greatly reduced IAV replication and release. Notably, at a very low concentration of 0.1 nM that is insufficient to reduce lysosome number, Baf-A1retained the capacity to significantly impair IAV nuclear accumulation as well as IAV replication and release. In contrast to the effects of high concentrations of Baf-A1, very low concentrations did not exhibit cytotoxic effects or induce apoptotic cell death, based on morphological and FACS analyses. In conclusion, our results reveal that low-concentration Baf-A1is an effective inhibitor of IAV replication, without impacting host cell viability.

scholarly journals RpoH Mediates the Expression of Some, but Not All, Genes Induced in Neisseria gonorrhoeae Adherent to Epithelial Cells

2006 ◽  
Vol 74 (5) ◽  
pp. 2767-2776 ◽  
Author(s):  
Ying Du ◽  
Cindy Grove Arvidson
Keyword(s):  
Epithelial Cells ◽  
Neisseria Gonorrhoeae ◽  
Host Cell ◽  
Infection Process ◽  
Host Cells ◽  
Cell Contact ◽  
Transmitted Infection ◽  
New Host ◽  
Sexually Transmitted ◽  
Cell Induction

ABSTRACT Neisseria gonorrhoeae (gonococcus [GC]), is highly adapted to the human host, the only known reservoir for gonococcal infection. However, since it is sexually transmitted, infection of a new host likely requires a regulatory response on the part of the gonococcus to respond to this significant change in environment. We previously showed that adherence of gonococci to epithelial cells results in changes of gene expression in the bacteria that presumably prepare them for subsequent steps in the infection process. Expression of the heat shock sigma factor gene, rpoH, was shown to be important for the invasion step, as gonococci depleted for rpoH were reduced in their ability to invade epithelial cells. Here, we show that of the genes induced in adherent gonococci, two are part of the gonococcal RpoH regulon. When RpoH is depleted, expression of these genes is no longer induced by host cell contact, indicating that RpoH is mediating the host cell induction response of these genes. One RpoH-dependent gene, NGO0376, is shown to be important for invasion of epithelial cells, consistent with earlier observations that RpoH is necessary for this step of infection. Two genes, NGO1684 and NGO0340, while greatly induced by host cell contact, were found to be RpoH independent, indicating that more than one regulator is involved in the response to host cell contact. Furthermore, NGO0340, but not NGO1684, was shown to be important for both adherence and invasion of epithelial cells, suggesting a complex regulatory network in the response of gonococci to contact with host cells.

scholarly journals Identification of Campylobacter jejuni Genes Involved in Its Interaction with Epithelial Cells

2010 ◽  
Vol 78 (8) ◽  
pp. 3540-3553 ◽  
Author(s):  
Veronica Novik ◽  
Dirk Hofreuter ◽  
Jorge E. Galán
Keyword(s):  
Animal Model ◽  
Epithelial Cells ◽  
Host Cell ◽  
Campylobacter Jejuni ◽  
Host Cells ◽  
Drastic Reduction ◽  
Mutagenesis Screen ◽  
Infectious Gastroenteritis ◽  
Industrialized Nations ◽  
Host Cell Interactions

ABSTRACT Campylobacter jejuni is the leading cause of infectious gastroenteritis in industrialized nations. Its ability to enter and survive within nonphagocytic cells is thought to be very important for pathogenesis. However, little is known about the C. jejuni determinants that mediate these processes. Through an extensive transposon mutagenesis screen, we have identified several loci that are required for C. jejuni efficient entry and survival within epithelial cells. Among these loci, insertional mutations in aspA, aspB, and sodB resulted in drastic reduction in C. jejuni entry and/or survival within host cells and a severe defect in colonization in an animal model. The implications of these findings for the understanding of C. jejuni-host cell interactions are discussed.

scholarly journals Intracellular Staphylococcus aureus employs the cysteine protease staphopain A to induce host cell death in epithelial cells

2020 ◽  
Author(s):  
Kathrin Stelzner ◽  
Tobias Hertlein ◽  
Aneta Sroka ◽  
Adriana Moldovan ◽  
Kerstin Paprotka ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Death ◽  
Epithelial Cells ◽  
Host Cell ◽  
Cysteine Protease ◽  
Host Cells ◽  
Upper Respiratory Tract ◽  
Intracellular Replication ◽  
Tissue Destruction ◽  
Host Cell Death

AbstractStaphylococcus aureus is a major human pathogen, which can invade and survive in non-professional and professional phagocytes. Intracellularity is thought to contribute to pathogenicity and persistence of the bacterium. Upon internalization by epithelial cells, cytotoxic S. aureus strains can escape from the phagosome, replicate in the cytosol and induce host cell death. Here, we identified a staphylococcal cysteine protease to induce cell death by intracellular S. aureus after translocation into the host cell cytoplasm. We demonstrated that loss of staphopain A function leads to delayed onset of host cell death and prolonged intracellular replication of S. aureus in epithelial cells. Overexpression of staphopain A in a non-cytotoxic strain facilitated intracellular killing of the host cell even in the absence of detectable intracellular replication. Moreover, staphopain A contributed to efficient colonization of the lung in a mouse pneumonia model. Our study suggests that staphopain A is utilized by S. aureus to mediate escape from the host cell and thus contributes to tissue destruction and dissemination of infection.Author SummaryStaphylococcus aureus is a well-known antibiotic-resistant pathogen that emerges in hospital and community settings and can cause a variety of diseases ranging from skin abscesses to lung inflammation and blood poisoning. The bacterium asymptomatically colonizes the upper respiratory tract and skin of about one third of the human population and takes advantage of opportune conditions, like immunodeficiency or breached barriers, to cause infection. Although S. aureus is not regarded as a professional intracellular bacterium, it can be internalized by human cells and subsequently exit the host cells by induction of cell death, which is considered to cause tissue destruction and spread of infection. The bacterial virulence factors and underlying molecular mechanisms involved in the intracellular lifestyle of S. aureus remain largely unknown. We identified a bacterial cysteine protease to contribute to host cell death mediated by intracellular S. aureus. Staphopain A induced killing of the host cell after translocation of the pathogen into the cell cytosol, while bacterial proliferation was not required. Further, the protease enhanced survival of the pathogen during lung infection. These findings reveal a novel, intracellular role for the bacterial protease staphopain A.

scholarly journals Intracellular Group A Streptococcus Induces Golgi Fragmentation To Impair Host Defenses through Streptolysin O and NAD-Glycohydrolase

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takashi Nozawa ◽  
Junpei Iibushi ◽  
Hirotaka Toh ◽  
Atsuko Minowa-Nozawa ◽  
Kazunori Murase ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Virulence Factors ◽  
Golgi Complex ◽  
Host Cells ◽  
Bacterial Invasion ◽  
Epithelial Barrier ◽  
Nad Glycohydrolase ◽  
Streptolysin O ◽  
Group A ◽  
Golgi Fragmentation

ABSTRACT Group A Streptococcus (GAS; Streptococcus pyogenes) is a major human pathogen that causes streptococcal pharyngitis, skin and soft tissue infections, and life-threatening conditions such as streptococcal toxic-shock syndrome. During infection, GAS not only invades diverse host cells but also injects effector proteins such as NAD-glycohydrolase (Nga) into the host cells through a streptolysin O (SLO)-dependent mechanism without invading the cells; Nga and SLO are two major virulence factors that are associated with increased bacterial virulence. Here, we have shown that the invading GAS induces fragmentation of the Golgi complex and inhibits anterograde transport in the infected host cells through the secreted toxins SLO and Nga. GAS infection-induced Golgi fragmentation required both bacterial invasion and SLO-mediated Nga translocation into the host cytosol. The cellular Golgi network is critical for the sorting of surface molecules and is thus essential for the integrity of the epithelial barrier and for the immune response of macrophages to pathogens. In epithelial cells, inhibition of anterograde trafficking by invading GAS and Nga resulted in the redistribution of E-cadherin to the cytosol and an increase in bacterial translocation across the epithelial barrier. Moreover, in macrophages, interleukin-8 secretion in response to GAS infection was found to be suppressed by intracellular GAS and Nga. Our findings reveal a previously undescribed bacterial invasion-dependent function of Nga as well as a previously unrecognized GAS-host interaction that is associated with GAS pathogenesis. IMPORTANCE Two prominent virulence factors of group A Streptococcus (GAS), streptolysin O (SLO) and NAD-glycohydrolase (Nga), are linked to enhanced pathogenicity of the prevalent GAS strains. Recent advances show that SLO and Nga are important for intracellular survival of GAS in epithelial cells and macrophages. Here, we found that invading GAS disrupts the Golgi complex in host cells through SLO and Nga. We show that GAS-induced Golgi fragmentation requires bacterial invasion into host cells, SLO pore formation activity, and Nga NADase activity. GAS-induced Golgi fragmentation results in the impairment of the epithelial barrier and chemokine secretion in macrophages. This immune inhibition property of SLO and Nga by intracellular GAS indicates that the invasion of GAS is associated with virulence exerted by SLO and Nga.

scholarly journals Disruption of the Salmonella-Containing Vacuole Leads to Increased Replication of Salmonella enterica Serovar Typhimurium in the Cytosol of Epithelial Cells

2002 ◽  
Vol 70 (6) ◽  
pp. 3264-3270 ◽  
Author(s):  
John H. Brumell ◽  
Patrick Tang ◽  
Michelle L. Zaharik ◽  
B. Brett Finlay
Keyword(s):  
Epithelial Cells ◽  
Host Cell ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Host Cells ◽  
Intracellular Pathogen ◽  
Wild Type ◽  
Vacuolar Compartment ◽  
Serovar Typhimurium ◽  
Endosomal System

ABSTRACT Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that inhabits a vacuolar compartment, called the Salmonella-containing vacuole (SCV), in infected host cells. Maintenance of the SCV is accomplished by SifA, and mutants of this Salmonella pathogenicity island 2 type III effector replicate more efficiently in epithelial cells. Here we demonstrate that enhanced replication of sifA mutants occurs in the cytosol of these cells. Increased replication of wild-type bacteria was also observed in cells treated with wortmannin or expressing Rab5 Q79L or Rab7 N125I, all of which caused a loss of SCV integrity. Our findings demonstrate the requirement of the host cell endosomal system for maintenance of the SCV and that loss of this compartment allows increased replication of serovar Typhimurium in the cytosol of epithelial cells.

scholarly journals A diarrheal pathogen, enteropathogenic Escherichia coli (EPEC), triggers a flux of inositol phosphates in infected epithelial cells.

1994 ◽  
Vol 179 (3) ◽  
pp. 993-998 ◽  
Author(s):  
V Foubister ◽  
I Rosenshine ◽  
B B Finlay
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Host Cell ◽  
Tyrosine Phosphorylation ◽  
Inositol Phosphates ◽  
Protein Kinase Inhibitors ◽  
Cell Protein ◽  
Bacterial Invasion ◽  
Enteropathogenic Escherichia Coli ◽  
Cytoskeletal Rearrangement

Enteropathogenic Escherichia coli (EPEC) is a bacterial pathogen that causes diarrhea in infants by adhering to intestinal epithelial cells. EPEC induces host cell protein phosphorylation and increases intracellular calcium levels that may function to initiate cytoskeletal rearrangement. We found that EPEC triggers the release of inositol phosphates (IPs) after adherence of bacteria to cultured epithelial cells. We also demonstrated that the EPEC-induced flux of IPs precedes actin rearrangement and bacterial invasion. EPEC mutants and tyrosine protein kinase inhibitors were used to establish that formation of IPs is dependent on tyrosine phosphorylation of a 90-kD HeLa protein. Collectively these results suggest that EPEC-induced tyrosine phosphorylation of a host cell substrate(s) leads to release of IPs, which may then trigger cytoskeletal rearrangement.

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