The role of Tir, EspA, and NleB in the colonization of cattle by Shiga toxin producingEscherichia coliO26:H11

2010 ◽  
Vol 56 (9) ◽  
pp. 739-747 ◽  
Author(s):  
Olga Misyurina ◽  
David J. Asper ◽  
Wanyin Deng ◽  
B. Brett Finlay ◽  
Dragan Rogan ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Shiga Toxin ◽  
Intestinal Tract ◽  
In Vivo Model ◽  
Intestinal Epithelial ◽  
Fecal Shedding ◽  
Human Intestinal Epithelial Cells ◽  
Uremic Syndrome

Shiga toxin producing Escherichia coli (STEC) O26:H11 is an enteric pathogen capable of causing severe hemorrhagic colitis that can lead to hemolytic uremic syndrome. This organism is able to colonize cattle and human intestinal epithelial cells by secreting effectors via a type III secretion system (T3SS). In this investigation, we examined the role of 2 effectors, Tir and NleB, and the structural translocator component EspA in the adherence of STEC to epithelial cells and in the colonization of cattle. Isogenic deletion mutants were constructed and using microscopy and flow cytometry compared to the wild-type strain in their ability to adhere to HEp-2 cells. A competitive assay was also used to measure the capacity of the mutants to colonize the intestinal tract of cattle, where both the mutant and the parental strains were introduced orally at the same time. Genomic DNA was extracted from enriched fecal samples collected at various time points, and quantitative real-time PCR was used to quantify bacteria. A significant reduction in fecal shedding was observed, and adherence to HEp-2 cells was decreased for the tir and espA mutants. Deletion of the nleB gene did not have a significant effect on the adherence of HEp-2 cells; however, in an in vivo model, it strongly reduced the ability of STEC O26:H11 to colonize the bovine intestinal tract.

scholarly journals Expression of lysophosphatidic acid receptor 5 is necessary for the regulation of intestinal Na+/H+ exchanger 3 by lysophosphatidic acid in vivo

2018 ◽  
Vol 315 (4) ◽  
pp. G433-G442 ◽  
Author(s):  
Kayte A. Jenkin ◽  
Peijian He ◽  
C. Chris Yun
Keyword(s):  
Epithelial Cells ◽  
Lysophosphatidic Acid ◽  
Direct Evidence ◽  
Intestinal Epithelial Cells ◽  
Regulatory Role ◽  
Intestinal Epithelial ◽  
Fluid Absorption ◽  
Wild Type

Lysophosphatidic acid (LPA) is a bioactive lipid molecule, which regulates a broad range of pathophysiological processes. Recent studies have demonstrated that LPA modulates electrolyte flux in the intestine, and its potential as an antidiarrheal agent has been suggested. Of six LPA receptors, LPA5 is highly expressed in the intestine. Recent studies by our group have demonstrated activation of Na+/H+ exchanger 3 (NHE3) by LPA5. However, much of what has been elucidated was achieved using colonic cell lines that were transfected to express LPA5. In the current study, we engineered a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC, and investigated the role of LPA5 in NHE3 regulation and fluid absorption in vivo. The intestine of Lpar5ΔIEC mice appeared morphologically normal, and the stool frequency and fecal water content were unchanged compared with wild-type mice. Basal rates of NHE3 activity and fluid absorption and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5. NHE3 activation involves trafficking of NHE3 from the terminal web to microvilli, and this mobilization of NHE3 by LPA was abolished in Lpar5ΔIEC mice. Dysregulation of NHE3 was specific to LPA, and insulin and cholera toxin were able to stimulate and inhibit NHE3, respectively, in both wild-type and Lpar5ΔIEC mice. The current study for the first time demonstrates the necessity of LPA5 in LPA-mediated stimulation of NHE3 in vivo. NEW & NOTEWORTHY This study is the first to assess the role of LPA5 in NHE3 regulation and fluid absorption in vivo using a mouse that lacks LPA5 in intestinal epithelial cells, Lpar5ΔIEC. Basal rates of NHE3 activity and fluid absorption, and total NHE3 expression were not changed in Lpar5ΔIEC mice. However, LPA did not activate NHE3 activity or fluid absorption in Lpar5ΔIEC mice, providing direct evidence for the regulatory role of LPA5.

scholarly journals Characterization of Candidate Live Oral Salmonella typhi Vaccine Strains Harboring Defined Mutations inaroA, aroC, and htrA

1999 ◽  
Vol 67 (2) ◽  
pp. 700-707 ◽  
Author(s):  
David C. Lowe ◽  
Tor C. Savidge ◽  
Derek Pickard ◽  
Lars Eckmann ◽  
Martin F. Kagnoff ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Salmonella Typhi ◽  
Scid Mice ◽  
Intestinal Epithelial ◽  
Human Intestinal Epithelial Cells ◽  
U937 Macrophage ◽  
Ht 29

ABSTRACT The properties of two candidate Salmonella typhi-based live oral typhoid vaccine strains, BRD691 (S. typhi Ty2 harboring mutations in aroA and aroC) and BRD1116 (S. typhi Ty2 harboring mutations inaroA, aroC, and htrA), were compared in a number of in vitro and in vivo assays. BRD1116 exhibited an increased susceptibility to oxidative stress compared with BRD691, but both strains were equally resistant to heat shock. Both strains showed a similar ability to invade Caco-2 and HT-29 epithelial cells and U937 macrophage-like cells, but BRD1116 was less efficient at surviving in epithelial cells than BRD691. BRD1116 and BRD691 were equally susceptible to intracellular killing within U937 cells. Similar findings were demonstrated in vivo, with BRD1116 being less able to survive and translocate to secondary sites of infection when inoculated into the lumen of human intestinal xenografts in SCID mice. However, translocation of BRD1116 to spleens and livers in SCID mice occurred as efficiently as that of BRD691 when inoculated intraperitonally. The ability of BRD1116 to increase the secretion of interleukin-8 following infection of HT-29 epithelial cells was comparable to that of BRD691. Therefore, loss of the HtrA protease inS. typhi does not seem to alter its ability to invade epithelial cells or macrophages or to induce proinflammatory cytokines such as IL-8 but significantly reduces intracellular survival in human intestinal epithelial cells in vitro and in vivo.

scholarly journals EnterohemorrhagicEscherichia coliinfection stimulates Shiga toxin 1 macropinocytosis and transcytosis across intestinal epithelial cells

2011 ◽  
Vol 301 (5) ◽  
pp. C1140-C1149 ◽  
Author(s):  
Valeriy Lukyanenko ◽  
Irina Malyukova ◽  
Ann Hubbard ◽  
Michael Delannoy ◽  
Edgar Boedeker ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Shiga Toxin ◽  
Molecular Mechanisms ◽  
Intestinal Epithelial Cells ◽  
Enterohemorrhagic Escherichia Coli ◽  
Intestinal Epithelial ◽  
Systemic Complications ◽  
E Coli ◽  
Systemic Spread ◽  
Uremic Syndrome

Gastrointestinal infection with Shiga toxins producing enterohemorrhagic Escherichia coli causes the spectrum of gastrointestinal and systemic complications, including hemorrhagic colitis and hemolytic uremic syndrome, which is fatal in ∼10% of patients. However, the molecular mechanisms of Stx endocytosis by enterocytes and the toxins cross the intestinal epithelium are largely uncharacterized. We have studied Shiga toxin 1 entry into enterohemorrhagic E. coli-infected intestinal epithelial cells and found that bacteria stimulate Shiga toxin 1 macropinocytosis through actin remodeling. This enterohemorrhagic E. coli-caused macropinocytosis occurs through a nonmuscle myosin II and cell division control 42 (Cdc42)-dependent mechanism. Macropinocytosis of Shiga toxin 1 is followed by its transcytosis to the basolateral environment, a step that is necessary for its systemic spread. Inhibition of Shiga toxin 1 macropinocytosis significantly decreases toxin uptake by intestinal epithelial cells and in this way provides an attractive, antibiotic-independent strategy for prevention of the harmful consequences of enterohemorrhagic E. coli infection.

scholarly journals Critical Role of Type III Interferon in Controlling SARS-CoV-2 Infection in Human Intestinal Epithelial Cells

Cell Reports ◽  
2020 ◽  
Vol 32 (1) ◽  
pp. 107863 ◽  
Author(s):  
Megan L. Stanifer ◽  
Carmon Kee ◽  
Mirko Cortese ◽  
Camila Metz Zumaran ◽  
Sergio Triana ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Critical Role ◽  
Intestinal Epithelial ◽  
Type Iii ◽  
Human Intestinal Epithelial Cells ◽  
Type Iii Interferon
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