scholarly journals A Positive Regulatory Loop Controls Expression of the Locus of Enterocyte Effacement-Encoded Regulators Ler and GrlA

2005 ◽  
Vol 187 (23) ◽  
pp. 7918-7930 ◽  
Author(s):  
Jeannette Barba ◽  
Víctor H. Bustamante ◽  
Mario A. Flores-Valdez ◽  
Wanyin Deng ◽  
B. Brett Finlay ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Virulence Genes ◽  
Intestinal Epithelial Cells ◽  
Transcriptional Response ◽  
Transcriptional Regulators ◽  
Intestinal Epithelial ◽  
Regulatory Motifs ◽  
Essential Step ◽  
Enterocyte Effacement ◽  
Regulatory Loop

ABSTRACT The formation of attaching and effacing (A/E) lesions on intestinal epithelial cells is an essential step in the pathogenesis of human enteropathogenic and enterohemorrhagic Escherichia coli and of the mouse pathogen Citrobacter rodentium. The genes required for the development of the A/E phenotype are located within a pathogenicity island known as the locus of enterocyte effacement (LEE). The LEE-encoded transcriptional regulators Ler, an H-NS-like protein, and GrlA, a member of a novel family of transcriptional activators, positively control the expression of the genes located in the LEE and their corresponding virulence. In this study, we used C. rodentium as a model to study the mechanisms controlling the expression of Ler and GrlA. By deletion analysis of the ler and grlRA regulatory regions and complementation experiments, negative and positive cis-acting regulatory motifs were identified that are essential for the regulation of both genes. This analysis confirmed that GrlA is required for the activation of ler, but it also showed that Ler is required for the expression of grlRA, revealing a novel regulatory loop controlling the optimal expression of virulence genes in A/E pathogens. Furthermore, our results indicate that Ler and GrlA induce the expression of each other by, at least in part, counteracting the repression mediated by H-NS. However, whereas GrlA is still required for the optimal expression of ler even in the absence of H-NS, Ler is not needed for the expression of grlRA in the absence of H-NS. This type of transcriptional positive regulatory loop represents a novel mechanism in pathogenic bacteria that is likely required to maintain an appropriate spatiotemporal transcriptional response during infection.

Oxidative stress enhances IL-8 and inhibits CCL20 production from intestinal epithelial cells in response to bacterial flagellin

2010 ◽  
Vol 299 (3) ◽  
pp. G733-G741 ◽  
Author(s):  
Sabine M. Ivison ◽  
Ce Wang ◽  
Megan E. Himmel ◽  
Jared Sheridan ◽  
Jonathan Delano ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Intestinal Epithelial Cells ◽  
Host Cells ◽  
Dependent Manner ◽  
Intestinal Epithelial ◽  
Chemokine Production ◽  
Molecular Signals

Intestinal epithelial cells act as innate immune sentinels, as the first cells that encounter diarrheal pathogens. They use pattern recognition molecules such as the Toll-like receptors (TLRs) to identify molecular signals found on microbes but not host cells or food components. TLRs cannot generally distinguish the molecular signals on pathogenic bacteria from those found in commensals, yet under healthy conditions epithelial immune responses are kept in check. We hypothesized that, in the setting of tissue damage or stress, intestinal epithelial cells would upregulate their responses to TLR ligands to reflect the greater need for immediate protection against pathogens. We treated Caco-2 cells with the TLR5 agonist flagellin in the presence or absence of H2O2 and measured chemokine production and intracellular signaling pathways. H2O2 increased flagellin-induced IL-8 (CXCL8) production in a dose-dependent manner. This was associated with synergistic phosphorylation of p38 MAP kinase and with prolonged I-κB degradation and NF-κB activation. The H2O2-mediated potentiation of IL-8 production required the activity of p38, tyrosine kinases, phospholipase Cγ, and intracellular calcium, but not protein kinase C or protein kinase D. H2O2 prolonged and augmented NF-κB activation by flagellin. In contrast to IL-8, CCL20 (MIP3α) production by flagellin was reduced by H2O2, and this effect was not calcium dependent. Oxidative stress biases intestinal epithelial responses to flagellin, leading to increased production of IL-8 and decreased production of CCL20. This suggests that epithelial cells are capable of sensing the extracellular environment and adjusting their antimicrobial responses accordingly.

scholarly journals Horizontally Acquired Polysaccharide-Synthetic Gene Cluster From Weissella cibaria Boosts the Probiotic Property of Lactiplantibacillus plantarum

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuqi Gao ◽  
Mingze Niu ◽  
Xiaohui Yu ◽  
Tingting Bao ◽  
Zhaowei Wu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Gene Cluster ◽  
Pathogenic Bacteria ◽  
Intestinal Epithelial Cells ◽  
Probiotic Bacteria ◽  
Synthetic Gene ◽  
Probiotic Properties ◽  
Intestinal Epithelial ◽  
Weissella Cibaria ◽  
Probiotic Property

Lactiplantibacillus plantarum are probiotic bacteria, maintaining the integrity of the gastrointestinal epithelial barrier, and preventing the infection of pathogenic bacteria. Exopolysaccharides (EPSs) are often involved in the probiotic property of L. plantarum. Here, we identified a new EPS-synthetic gene cluster, cpsWc, carrying 13 genes, laid on a large plasmid in a well-characterized probiotic L. plantarum strain LTC-113. The cpsWc gene cluster was horizontally acquired from Weissella cibaria, enhancing the biofilm formation ability of the host strain and its tolerance to harsh environmental stresses, including heat, acid, and bile. Transfer of cpsWc also conferred the probiotic properties to other L. plantarum strains. Moreover, cpsWc strengthened the adhesion of LTC-113 to intestinal epithelial cells. Both the cpsWc-carrying LTC-113 and its EPSs per se effectively attenuated the LPS-induced pro-inflammatory effect of intestinal epithelial cells, and inhibited the adhesion of pathogenic bacteria, such as S. typhimurium and E. coli by exclusion and competition. The newly identified cpsWc gene cluster emphasized the contribution of mobile EPS-synthetic element on the probiotic activity of L. plantarum, and shed a light on the engineering of probiotic bacteria.

scholarly journals Wingless homolog Wnt11 suppresses bacterial invasion and inflammation in intestinal epithelial cells

2011 ◽  
Vol 301 (6) ◽  
pp. G992-G1003 ◽  
Author(s):  
Xingyin Liu ◽  
Shaoping Wu ◽  
Yinglin Xia ◽  
Xi Emma Li ◽  
Yuxuan Xia ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Intestinal Inflammation ◽  
Intestinal Epithelial Cells ◽  
Enteric Bacteria ◽  
Bacterial Invasion ◽  
Intestinal Epithelial ◽  
Induced Apoptosis ◽  
In Cells

Wnt11 plays an essential role in gastrointestinal epithelial proliferation, and previous investigations have focused on development and immune responses. However, the roles of how enteric bacteria regulate Wnt11 and how Wnt11 modulates the host response to pathogenic bacteria remain unexplored. This study investigated the effects of Salmonella infection on Wnt activation in intestinal epithelial cells. We found that Wnt11 mRNA and protein expression were elevated after Salmonella colonization. Wnt11 protein secretion in epithelial cells was also elevated after bacterial infection. Furthermore, we demonstrated that pathogenic Salmonella regulated Wnt11 expression and localization in vivo. We found a decrease in Salmonella invasion in cells with Wnt11 overexpression compared with cells with normal Wnt11 level. IL-8 mRNA in Wnt11-transfected cells was low; however, it was enhanced in cells with a low level of Wnt11 expression. Functionally, Wnt11 overexpression inhibited Salmonella-induced apoptosis. AvrA is a known bacterial effector protein that stabilizes β-catenin, the downstream regulator of Wnt signaling, and inhibits bacterially induced intestinal inflammation. We observed that Wnt11 expression, secretion, and transcriptional activity were regulated by Salmonella AvrA. Overall, Wnt11 is involved in the protection of the host intestinal cells by blocking the invasion of pathogenic bacteria, suppressing inflammation, and inhibiting apoptosis. Wnt11 is a novel and important contributor to intestinal homeostasis and host defense.

Adherence to and Invasion of Human Intestinal Epithelial Cells by Campylobacter jejuni and Campylobacter coli Isolates from Retail Meat Products

2006 ◽  
Vol 69 (4) ◽  
pp. 768-774 ◽  
Author(s):  
JIE ZHENG ◽  
JIANGHONG MENG ◽  
SHAOHUA ZHAO ◽  
RUBY SINGH ◽  
WENXIA SONG
Keyword(s):  
Epithelial Cells ◽  
Campylobacter Jejuni ◽  
Virulence Genes ◽  
Intestinal Epithelial Cells ◽  
Clinical Strain ◽  
Campylobacter Coli ◽  
Intestinal Epithelial ◽  
T84 Cells ◽  
Human Intestinal Epithelial Cells ◽  
Retail Meat

The abilities of 34 Campylobacter jejuni and 9 Campylobacter coli isolates recovered from retail meats to adhere to and invade human intestinal epithelial T84 cells were examined and compared with those of a well-characterized human clinical strain, C. jejuni 81-176, to better assess the pathogenic potential of these meat isolates. The meat isolates exhibited a wide range of adherence and invasion abilities; a few of the isolates adhered to and invaded T84 cells almost as well as did C. jejuni 81-176. There was a significant correlation between the adherence ability and the invasion ability of the Campylobacter isolates. The presence of eight putative virulence genes in these Campylobacter isolates that are potentially responsible for adherence and invasion or that encode cytolethal distending toxin was determined using PCR. All Campylobacter isolates possessed flaA, cadF, pldA, cdtA, cdtB, and cdtC, and most (91%) also contained the ciaB gene. However, the virB11 gene, carried by virulence plasmid pVir, was absent in almost all the Campylobacter isolates. Our findings indicated that C. jejuni and C. coli present in retail meat were diverse in their ability to adhere to and invade human intestinal epithelial cells and that the putative virulence genes were widespread among the Campylobacter isolates. Thus, despite of the presence of the putative virulence genes, only some but not all Campylobacter strains isolated from retail meat can effectively invade human intestinal epithelial cells in vitro.

scholarly journals The Small RNA PinT Contributes to PhoP-Mediated Regulation of theSalmonellaPathogenicity Island 1 Type III Secretion System inSalmonella entericaSerovar Typhimurium

2019 ◽  
Vol 201 (19) ◽  
Author(s):  
Kyungsub Kim ◽  
Alexander D. Palmer ◽  
Carin K. Vanderpool ◽  
James M. Slauch
Keyword(s):  
Epithelial Cells ◽  
Small Rna ◽  
Type Iii Secretion ◽  
Intestinal Epithelial Cells ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Intestinal Epithelial ◽  
Environmental Signals ◽  
Inflammatory Diarrhea ◽  
Regulatory Loop

ABSTRACTSalmonella entericaserovar Typhimurium induces inflammatory diarrhea and bacterial uptake into intestinal epithelial cells using theSalmonellapathogenicity island 1 (SPI1) type III secretion system (T3SS). HilA activates transcription of the SPI1 structural components and effector proteins. Expression ofhilAis activated by HilD, HilC, and RtsA, which act in a complex feed-forward regulatory loop. Many environmental signals and other regulators are integrated into this regulatory loop, primarily via HilD. After the invasion ofSalmonellainto host intestinal epithelial cells or during systemic replication in macrophages, the SPI T3SS is no longer required or expressed. We have shown that the two-component regulatory system PhoPQ, required for intracellular survival, represses the SPI1 T3SS mostly by controlling the transcription ofhilAandhilD. Here we show that PinT, one of the PhoPQ-regulated small RNAs (sRNAs), contributes to this regulation by repressinghilAandrtsAtranslation. PinT base pairs with both thehilAandrtsAmRNAs, resulting in translational inhibition ofhilA, but also induces degradation of thertstranscript. PinT also indirectly represses expression of FliZ, a posttranslational regulator of HilD, and directly represses translation ofssrB, encoding the primary regulator of the SPI2 T3SS. Ourin vivomouse competition assays support the concept that PinT controls a series of virulence genes at the posttranscriptional level in order to adaptSalmonellafrom the invasion stage to intracellular survival.IMPORTANCESalmonellais one of the most important food-borne pathogens, infecting over one million people in the United States every year. These bacteria use a needle-like device to interact with intestinal epithelial cells, leading to invasion of the cells and induction of inflammatory diarrhea. A complex regulatory network controls expression of the invasion system in response to numerous environmental signals. Here we explore the molecular mechanisms by which the small RNA PinT contributes to this regulation, facilitating inactivation of the system after invasion. PinT controls several important virulence systems inSalmonella, tuning the transition between different stages of infection.

Lactoferrin downregulates pro-inflammatory cytokines upexpressed in intestinal epithelial cells infected with invasive or noninvasive Escherichia coli strainsThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Function, and Applications, and has undergone the Journal’s usual peer review process.

2006 ◽  
Vol 84 (3) ◽  
pp. 351-357 ◽  
Author(s):  
Francesca Berlutti ◽  
Serena Schippa ◽  
Clara Morea ◽  
Serena Sarli ◽  
Brunella Perfetto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Inflammatory Cytokines ◽  
Pathogenic Bacteria ◽  
Intestinal Epithelial Cells ◽  
Peer Review Process ◽  
Bovine Lactoferrin ◽  
Intestinal Epithelial ◽  
E Coli ◽  
Pro Inflammatory Cytokines

Intestinal epithelial cells are able to differentially interact with commensal or pathogenic microorganisms, triggering a physiological or destructive inflammation, respectively. To mimic commensal–enteroinvasive bacteria–host cell interaction, we infected Caco-2 cells with noninvasive Escherichia coli HB101 and with recombinant invasive E. coli HB101(pRI203). Using DNA microarray mRNA profiling and ELISA assays, we studied the expression of several cytokine and cytokine-related genes in infected Caco-2 cells in the absence or presence of bovine lactoferrin (bLf). Infection of Caco-2 cells with the noninvasive strain induced a slight increase in the expression of interleukin 8 (IL-8), whereas infection with invasive E. coli HB101(pRI203) induced a significant increase in the expression of IL-8 as well as other pro-inflammatory cytokines. The addition of bLf, in native- or holo-form, did not influence expression of cytokine genes by uninfected Caco-2 cells, but it decreased expression of IL-8 by cells infected with E.coli HB101. Moreover, except for IL-8, bLfs dramatically downregulated pro-inflammatory cytokines upexpressed by Caco-2 cells infected with the invasive strain. Although IL-8 was decreased by bLfs, it remained upregulated, suggesting that it could be a signal of persistence of intracellular bacteria. The bLf ability to reduce expression of some pro-inflammatory cytokines, which appears independent of its iron saturation, might represent an important natural mechanism in regulating epithelial cell responses to pathogenic bacteria and in limiting cell damage and the spread of infections.

Analysis of the human intestinal epithelial cell transcriptional response to Lactobacillus acidophilus, Lactobacillus salivarius, Bifidobacterium lactis and Escherichia coli

2010 ◽  
Vol 1 (3) ◽  
pp. 283-295 ◽  
Author(s):  
H. Putaala ◽  
R. Barrangou ◽  
G. Leyer ◽  
A. Ouwehand ◽  
E. Bech Hansen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Lactobacillus Acidophilus ◽  
Intestinal Epithelial Cells ◽  
Transcriptional Response ◽  
Intestinal Epithelial ◽  
Transcriptional Responses ◽  
Lactobacillus Salivarius ◽  
Enterohaemorrhagic Escherichia Coli ◽  
Human Intestinal Epithelial Cells

The complex microbial population residing in the human gastrointestinal tract consists of commensal, potential pathogenic and beneficial species, which are probably perceived differently by the host and consequently could be expected to trigger specific transcriptional responses. Here, we provide a comparative analysis of the global in vitro transcriptional response of human intestinal epithelial cells to Lactobacillus acidophilus NCFM™, Lactobacillus salivarius Ls-33, Bifidobacterium animalis subsp. lactis 420, and enterohaemorrhagic Escherichia coli O157:H7 (EHEC). Interestingly, L. salivarius Ls-33 DCE-induced changes were overall more similar to those of B. lactis 420 than to L. acidophilus NCFM™, which is consistent with previously observed in vivo immunomodulation properties. In the gene ontology and pathway analyses both specific and unspecific changes were observed. Common to all was the regulation of apoptosis and adipogenesis, and lipid-metabolism related regulation by the probiotics. Specific changes such as regulation of cell-cell adhesion by B. lactis 420, superoxide metabolism by L. salivarius Ls-33, and regulation of MAPK pathway by L. acidophilus NCFM™ were noted. Furthermore, fundamental differences were observed between the pathogenic and probiotic treatments in the Toll-like receptor pathway, especially for adapter molecules with a lowered level of transcriptional activation of MyD88, TRIF, IRAK1 and TRAF6 by probiotics compared to EHEC. The results in this study provide insights into the relationship between probiotics and human intestinal epithelial cells, notably with regard to strain-specific responses, and highlight the differences between transcriptional responses to pathogenic and probiotic bacteria.

scholarly journals Intestinal Epithelial Cells and the Microbiome Undergo Swift Reprogramming at the Inception of Colonic Citrobacter rodentium Infection

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Eve G. D. Hopkins ◽  
Theodoros I. Roumeliotis ◽  
Caroline Mullineaux-Sanders ◽  
Jyoti S. Choudhary ◽  
Gad Frankel
Keyword(s):  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Intestinal Epithelial Cells ◽  
Cholesterol Homeostasis ◽  
Early Infection ◽  
Secretory Cells ◽  
Intestinal Epithelial ◽  
Citrobacter Rodentium ◽  
Content Type

ABSTRACT We used the mouse attaching and effacing (A/E) pathogen Citrobacter rodentium, which models the human A/E pathogens enteropathogenic Escherichia coli and enterohemorrhagic E. coli (EPEC and EHEC), to temporally resolve intestinal epithelial cell (IEC) responses and changes to the microbiome during in vivo infection. We found the host to be unresponsive during the first 3 days postinfection (DPI), when C. rodentium resides in the caecum. In contrast, at 4 DPI, the day of colonic colonization, despite only sporadic adhesion to the apex of the crypt, we observed robust upregulation of cell cycle and DNA repair processes, which were associated with expansion of the crypt Ki67-positive replicative zone, and downregulation of multiple metabolic processes (including the tricarboxylic acid [TCA] cycle and oxidative phosphorylation). Moreover, we observed dramatic depletion of goblet and deep crypt secretory cells and an atypical regulation of cholesterol homeostasis in IECs during early infection, with simultaneous upregulation of cholesterol biogenesis (e.g., 3-hydroxy-3-methylglutaryl–coenzyme A reductase [Hmgcr]), import (e.g., low-density lipoprotein receptor [Ldlr]), and efflux (e.g., AbcA1). We also detected interleukin 22 (IL-22) responses in IECs (e.g., Reg3γ) on the day of colonic colonization, which occurred concomitantly with a bloom of commensal Enterobacteriaceae on the mucosal surface. These results unravel a new paradigm in host-pathogen-microbiome interactions, showing for the first time that sensing a small number of pathogenic bacteria triggers swift intrinsic changes to the IEC composition and function, in tandem with significant changes to the mucosa-associated microbiome, which parallel innate immune responses. IMPORTANCE The mouse pathogen C. rodentium is a widely used model for colonic infection and has been a major tool in fundamental discoveries in the fields of bacterial pathogenesis and mucosal immunology. Despite extensive studies probing acute C. rodentium infection, our understanding of the early stages preceding the infection climax remains relatively undetailed. To this end, we apply a multiomics approach to resolve temporal changes to the host and microbiome during early infection. Unexpectedly, we found immediate and dramatic responses occurring on the day of colonic infection, both in the host intestinal epithelial cells and in the microbiome. Our study suggests changes in cholesterol and carbon metabolism in epithelial cells are instantly induced upon pathogen detection in the colon, corresponding with a shift to primarily facultative anaerobes constituting the microbiome. This study contributes to our knowledge of disease pathogenesis and mechanisms of barrier regulation, which is required for development of novel therapeutics targeting the intestinal epithelium.

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