scholarly journals Transmission Electron Microscopic Demonstration of Phagocytosis and Intracellular Processing of Segmented Filamentous Bacteria by Intestinal Epithelial Cells of the Chick Ileum

2000 ◽  
Vol 68 (11) ◽  
pp. 6496-6504 ◽  
Author(s):  
Koh-En Yamauchi ◽  
Johannes Snel
Keyword(s):  
Immune System ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Mucosal Immune System ◽  
Host Cells ◽  
Intestinal Lumen ◽  
Intestinal Epithelial ◽  
Filamentous Bacteria ◽  
Segmented Filamentous Bacteria ◽  
Transmission Electron

ABSTRACT Segmented filamentous bacteria (SFB) are autochthonous bacteria colonizing the ileum of many young animals by attaching to intestinal epithelial cells. These nonpathogenic bacteria strongly stimulate the mucosal immune system and induce intestinal epithelial cells to express major histocompatibility complex class II molecules. We tried to discover whether SFB are phagocytized and intracellularly processed by the host cells, which is indicative of antigen processing. The middle part of the ileum was extracted from 10- and 20-day-old broiler chicks (Gallus gallus domesticus). Samples were processed and examined by scanning and transmission electron microscopy (SEM and TEM, respectively). In SEM, no, few, medium, and dense SFB colonization levels were classified. In TEM of cells from animals with medium or dense SFB colonization levels, we could observe extracellular particles ranging from those only indenting the cell membrane to particles found in the cytoplasmatic area beyond the terminal web. These particles had a structural similarity with SFB that were floating freely in the intestinal lumen. Furthermore, we observed unlacing of the membrane and septum surrounding the extracellular particles and their incorporation into host cytoplasmatic components, which strongly suggests that these particles are phagocytized and intracellularly processed SFB. This conclusion is supported by TEM analysis of samples with no or few SFB, in which we failed to find these characteristic morphologies. The phagocytosis process described here could be an important trigger for the stimulating effect of SFB on the mucosal immune system.

scholarly journals Salmonella Typhimurium induces NAIP/NLRC4- and NLRP3/ASC-independent, caspase-1/4-dependent inflammasome activation in human intestinal epithelial cells

2021 ◽  
Author(s):  
Nawar Naseer ◽  
Renate Bauer ◽  
Jenna Zhang ◽  
Igor E. Brodsky ◽  
Isabella Rauch ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Adaptor Protein ◽  
Host Cells ◽  
Intestinal Lumen ◽  
Bacterial Invasion ◽  
Inflammasome Activation ◽  
Intestinal Epithelial ◽  
Secretion Systems ◽  
Caspase 1

Salmonella enterica serovar Typhimurium is a gram-negative pathogen that causes diseases ranging from gastroenteritis to systemic infection and sepsis. Salmonella uses type III secretion systems (T3SSs) to inject effectors into host cells. While these effectors are necessary for bacterial invasion and intracellular survival, intracellular delivery of T3SS products also enables detection of Salmonella by cytosolic immune sensors. Upon detecting translocated Salmonella ligands, these sensors form multimeric complexes called inflammasomes, which activate caspases that lead to proinflammatory cytokine release and pyroptosis. In particular, the Salmonella T3SS needle, inner rod, and flagellin proteins activate the NAIP/NLRC4 inflammasome in murine intestinal epithelial cells (IECs), which leads to restriction of bacterial replication and extrusion of infected IECs into the intestinal lumen, thereby preventing systemic dissemination of Salmonella . While these processes are studied quite well in mice, the role of the NAIP/NLRC4 inflammasome in human IECs remains unknown. Unexpectedly, we found the NAIP/NLRC4 inflammasome is dispensable for early inflammasome responses to Salmonella in both human intestinal epithelial cell lines and organoids. Additionally, the NLRP3 inflammasome and the adaptor protein ASC are not required for inflammasome activation in Caco-2 cells. Instead, we observed a partial requirement for caspase-1, and a necessity for caspase-4 and GSDMD pore-forming activity in mediating inflammasome responses to Salmonella in Caco-2 cells. These findings suggest that unlike murine IECs, human IECs do not rely on NAIP/NLRC4, and also do not use NLRP3/ASC. Instead, they primarily use caspases-1 and -4 to mediate early inflammasome responses to SPI-1-expressing Salmonella .

OmpD but not OmpC is involved in adherence ofSalmonella entericaserovar Typhimurium to human cells

2004 ◽  
Vol 50 (9) ◽  
pp. 719-727 ◽  
Author(s):  
Bochiwe Hara-Kaonga ◽  
Thomas G Pistole
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Human Cells ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
Human Macrophages ◽  
Significant Difference ◽  
Serovar Typhimurium

Conflicting reports exist regarding the role of porins OmpC and OmpD in infections due to Salmonella enterica serovar Typhimurium. This study investigated the role of these porins in bacterial adherence to human macrophages and intestinal epithelial cells. ompC and ompD mutant strains were created by transposon mutagenesis using P22-mediated transduction of Tn10 and Tn5 insertions, respectively, into wild-type strain 14028. Fluorescein-labeled wild-type and mutant bacteria were incubated with host cells at various bacteria to cell ratios for 1 h at 37 °C and analyzed by flow cytometry. The mean fluorescence intensity of cells with associated wild-type and mutant bacteria was used to estimate the number of bacteria bound per host cell. Adherence was also measured by fluorescence microscopy. Neither assay showed a significant difference in binding of the ompC mutant and wild-type strains to the human cells. In contrast, the ompD mutant exhibited lowered binding to both cell types. Our findings suggest that OmpD but not OmpC is involved in the recognition of Salmonella serovar Typhimurium by human macrophages and intestinal epithelial cells.Key words: Salmonella, adherence, porins, intestinal epithelial cells, macrophage.

Protease-activated receptor-1 stimulates Ca2+-dependent Cl−secretion in human intestinal epithelial cells

2001 ◽  
Vol 281 (2) ◽  
pp. G323-G332 ◽  
Author(s):  
M. C. Buresi ◽  
E. Schleihauf ◽  
N. Vergnolle ◽  
A. Buret ◽  
J. L. Wallace ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Short Circuit ◽  
Intestinal Lumen ◽  
Epithelial Cell Line ◽  
Intracellular Camp ◽  
Intestinal Epithelial ◽  
Rt Pcr ◽  
Human Intestinal Epithelial Cells ◽  
Protease Activated Receptor 1

The thrombin receptor, protease-activated receptor-1 (PAR-1), has wide tissue distribution and is involved in many physiological functions. Because thrombin is in the intestinal lumen and mucosa during inflammation, we sought to determine PAR-1 expression and function in human intestinal epithelial cells. RT-PCR showed PAR-1 mRNA expression in SCBN cells, a nontransformed duodenal epithelial cell line. Confluent SCBN monolayers mounted in Ussing chambers responded to PAR-1 activation with a Cl−-dependent increase in short-circuit current. The secretory effect was blocked by BaCl2and the Ca2+-ATPase inhibitor thapsigargin, but not by the L-type Ca2+channel blocker verapamil or DIDS, the nonselective inhibitor of Ca2+-dependent Cl−transport. Responses to thrombin and PAR-1-activating peptides exhibited auto- and crossdesensitization. Fura 2-loaded SCBN cells had increased fluorescence after PAR-1 activation, indicating increased intracellular Ca2+. RT-PCR showed that SCBN cells expressed mRNA for the cystic fibrosis transmembrane conductance regulator (CFTR) and hypotonicity-activated Cl−channel-2 but not for the Ca2+-dependent Cl−channel-1. PAR-1 activation failed to increase intracellular cAMP, suggesting that the CFTR channel is not involved in the Cl−secretory response. Our data demonstrate that PAR-1 is expressed on human intestinal epithelial cells and regulates a novel Ca2+-dependent Cl−secretory pathway. This may be of clinical significance in inflammatory intestinal diseases with elevated thrombin levels.

Nitric oxide regulates energy metabolism and Bcl-2 expression in intestinal epithelial cells

1998 ◽  
Vol 274 (5) ◽  
pp. G797-G801 ◽  
Author(s):  
Manabu Nishikawa ◽  
Kenta Takeda ◽  
Eisuke F. Sato ◽  
Tetso Kuroki ◽  
Masayasu Inoue
Keyword(s):  
Nitric Oxide ◽  
Epithelial Cells ◽  
Prolonged Exposure ◽  
Intestinal Epithelial Cells ◽  
Enteric Bacteria ◽  
Intestinal Lumen ◽  
Intestinal Epithelial ◽  
Mucosal Cells ◽  
Respiration Of Mitochondria ◽  
Induced Changes

Nitric oxide (NO) inhibits the respiration of mitochondria and enteric bacteria, particularly under low O2concentration, and induces apoptosis of various types of cells. To gain insight into the molecular role of NO in the intestine, we examined its effects on the respiration, Ca2+status, and expression of Bcl-2 in cultured intestinal epithelial cells (IEC-6). NO reversibly inhibited the respiration of IEC-6 cells, especially under physiologically low O2concentration. Although NO elevated cytosolic Ca2+as determined by the fura 2 method, the cells were fairly resistant to NO. Kinetic analysis revealed that prolonged exposure to NO elevated the levels of Bcl-2 and suppressed the NO-induced changes in Ca2+status of the cells. Because Bcl-2 possesses antiapoptotic function, toxic NO effects might appear minimally in enterocytes enriched with Bcl-2. Thus NO might effectively exhibit its antibacterial action in anaerobic intestinal lumen without inducing apoptosis of Bcl-2-enriched mucosal cells.

Efficacy of Plant-Derived Antimicrobials in Controlling Enterohemorrhagic Escherichia coli Virulence In Vitro

2016 ◽  
Vol 79 (11) ◽  
pp. 1965-1970 ◽  
Author(s):  
SANGEETHA ANANDA BASKARAN ◽  
ANUP KOLLANOOR-JOHNY ◽  
MEERA SURENDRAN NAIR ◽  
KUMAR VENKITANARAYANAN
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Antimicrobial Agents ◽  
Intestinal Epithelial Cells ◽  
Enterohemorrhagic Escherichia Coli ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Virulence Gene Expression ◽  
Human Intestinal Epithelial Cells

ABSTRACTEscherichia coli O157:H7 is a major foodborne pathogen that can cause serious human illness characterized by hemorrhagic diarrhea and kidney failure. The pathology of enterohemorrhagic E. coli O157:H7 (EHEC) infection is primarily mediated by verotoxins, which bind to the globotriaosylceramide receptor on host cells. Antibiotics are contraindicated for treating EHEC infection because they lead to increased verotoxin release, thereby increasing the risk of renal failure and death in patients. Thus, alternative strategies are needed for controlling EHEC infections in humans. This study investigated the effect of subinhibitory concentrations of five plant-derived antimicrobial agents (PDAs) that are generally considered as safe, i.e., trans-cinnamaldehyde, eugenol, carvacrol, thymol, and β-resorcylic acid, on EHEC motility, adhesion to human intestinal epithelial cells, verotoxin production, and virulence gene expression. All tested PDAs reduced EHEC motility and attachment to human intestinal epithelial cells (P < 0.05) and decreased verotoxin synthesis by EHEC. The reverse transcription real-time PCR data revealed that PDAs decreased the expression of critical virulence genes in EHEC (P < 0.05). The results collectively suggest that these PDAs could be used to reduce EHEC virulence, but follow-up studies in animal models are necessary to validate these findings.

scholarly journals Simultaneous Exposure to Escherichia coli Heat-Labile and Heat-Stable Enterotoxins Increases Fluid Secretion and Alters Cyclic Nucleotide and Cytokine Production by Intestinal Epithelial Cells

2014 ◽  
Vol 82 (12) ◽  
pp. 5308-5316 ◽  
Author(s):  
Lisa T. Read ◽  
Rachel W. Hahn ◽  
Carli C. Thompson ◽  
David L. Bauer ◽  
Elizabeth B. Norton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Diarrheal Disease ◽  
Water Movement ◽  
Intestinal Epithelial Cells ◽  
Intestinal Lumen ◽  
Intestinal Epithelial ◽  
Simultaneous Exposure ◽  
Heat Stable ◽  
Heat Labile

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) is a significant cause of diarrheal disease and death, especially in children in developing countries. ETEC causes disease by colonizing the small intestine and producing heat-labile toxin (LT), heat-stable toxin (ST), or both LT and ST (LT+ST). The majority of ETEC strains produce both ST and LT. Despite the prevalence of LT+ST-producing organisms, few studies have examined the physiologic or immunologic consequences of simultaneous exposure to these two potent enterotoxins. In the current report, we demonstrate that when LT and ST are both present, they increase water movement into the intestinal lumen over and above the levels observed with either toxin alone. As expected, cultured intestinal epithelial cells increased their expression of intracellular cyclic GMP (cGMP) when treated with ST and their expression of intracellular cyclic AMP (cAMP) when treated with LT. When both toxins were present, cGMP levels but not cAMP levels were synergistically elevated compared with the levels of expression caused by the corresponding single-toxin treatment. Our data also demonstrate that the levels of inflammatory cytokines produced by intestinal epithelial cells in response to LT are significantly reduced in animals exposed to both enterotoxins. These findings suggest that there may be complex differences between the epithelial cell intoxication and, potentially, secretory outcomes induced by ETEC strains expressing LT+ST compared with strains that express LT or ST only. Our results also reveal a novel mechanism wherein ST production may reduce the hosts' ability to mount an effective innate or adaptive immune response to infecting organisms.

scholarly journals Human Cytomegalovirus Infects Caco-2 Intestinal Epithelial Cells Basolaterally Regardless of the Differentiation State

2000 ◽  
Vol 74 (1) ◽  
pp. 513-517 ◽  
Author(s):  
Audrey Esclatine ◽  
Michel Lemullois ◽  
Alain L. Servin ◽  
Anne-Marie Quero ◽  
Monique Geniteau-Legendre
Keyword(s):  
Epithelial Cells ◽  
Human Cytomegalovirus ◽  
Intestinal Epithelial Cells ◽  
Severe Disease ◽  
Epithelial Cell Line ◽  
Intestinal Epithelial ◽  
Cmv Infection ◽  
Transmission Electron ◽  
Immunosuppressed Patients

ABSTRACT Human cytomegalovirus (CMV) causes severe disease in immunosuppressed patients and notably infects the gastrointestinal tract. To understand the interaction of CMV with intestinal epithelial cells, which are highly susceptible to CMV infection in vivo, we used the intestinal epithelial cell line Caco-2 and demonstrated that CMV enters predominantly through the basolateral surface of polarized Caco-2 cells. As shown by expression of all three classes of CMV proteins and by visualization of nucleocapsids by transmission electron microscopy, both poorly and fully differentiated Caco-2 cells were permissive to CMV replication. However, infection failed to produce infectious particles in Caco-2 cells, irrespective of the state of differentiation.

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