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In vitro Intestinal Mucosal Epithelial Responses to Wild-Type Salmonella Typhi and Attenuated Typhoid Vaccines.

Fiorentino M, Lammers KM, Levine MM, Sztein MB, Fasano A - Front Immunol (2013)

Bottom Line: Typhi exhibited alterations in the organization of tight junctions, increased paracellular permeability, and a rapid decrease in Trans-Epithelial Electrical Resistance as early as 4 h post-exposure.We conclude that wild-type S.Typhi causes marked transient alterations of the intestinal mucosa that are more pronounced than those observed with Ty21a or new generation attenuated typhoid vaccine candidates.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Mucosal Biology Research Center, University of Maryland School of Medicine Baltimore, MD, USA.

ABSTRACT
Typhoid fever, caused by S. Typhi, is responsible for approximately 200,000 deaths per year worldwide. Little information is available regarding epithelium-bacterial interactions in S. Typhi infection. We have evaluated in vitro the effects of wild-type S. Typhi, the licensed Ty21a typhoid vaccine and the leading strains CVD 908-htrA and CVD 909 vaccine candidates on intestinal barrier function and immune response. Caco2 monolayers infected with wild-type S. Typhi exhibited alterations in the organization of tight junctions, increased paracellular permeability, and a rapid decrease in Trans-Epithelial Electrical Resistance as early as 4 h post-exposure. S. Typhi triggered the secretion of interleukin (IL)-8 and IL-6. Caco2 cells infected with the attenuated strains exhibited a milder pro-inflammatory response with minimal disruption of the barrier integrity. We conclude that wild-type S. Typhi causes marked transient alterations of the intestinal mucosa that are more pronounced than those observed with Ty21a or new generation attenuated typhoid vaccine candidates.

No MeSH data available.


Related in: MedlinePlus

Trans-epithelial electrical resistance (TEER) responses of CaCo2 cell monolayers to wild-type S. Typhi, HK bacteria, and culture supernatants. (A) TEER changes upon infection with wild-type S. Typhi at different MOIs. (B) TEER in HK bacteria and culture supernatants (Cond. Media) treated monolayers. Data are expressed as means ± SEM for triplicate samples for all conditions tested. These results are representative of three experiments with similar results. #Denotes p < 0.001 of S. Typhi strains over t = 0 (ANOVA).
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Figure 1: Trans-epithelial electrical resistance (TEER) responses of CaCo2 cell monolayers to wild-type S. Typhi, HK bacteria, and culture supernatants. (A) TEER changes upon infection with wild-type S. Typhi at different MOIs. (B) TEER in HK bacteria and culture supernatants (Cond. Media) treated monolayers. Data are expressed as means ± SEM for triplicate samples for all conditions tested. These results are representative of three experiments with similar results. #Denotes p < 0.001 of S. Typhi strains over t = 0 (ANOVA).

Mentions: To investigate the effects of S. Typhi on mucosal barrier integrity, we infected Caco2 monolayers with S. Typhi at different MOIs. Since modulation and/or disruption of epithelial barrier function can be measured by changes in TEER, we used this technique to monitor alterations in mucosal permeability caused by the bacteria. As shown in Figure 1A we found that wild-type S. Typhi induced a decrease in TEER in the monolayer in a dose-dependent manner. All inoculation ratios used (MOIs of 40:1, 400:1, and 4000:1 bacteria:cell ratios, respectively) caused a significant drop in TEER [from 1147.0 ± 21.2 Ω.cm2 at baseline to 804.1 ± 37.5 Ω.cm2, 318.7 ± 38.2 Ω.cm2, and 252.6 ± 8.1 Ω.cm2, respectively] as early as 2 h post-infection. The decrease in TEER was even more dramatic at 4 h post-infection with TEER values of 527.6 ± 34.9 Ω.cm2, 206 ± 15.5 Ω.cm2, and 170.1 ± 1.6 Ω.cm2, respectively compared to baseline (1185.2 ± 40.0 Ω.cm2). At 4 h, bacteria were removed and monolayers were treated with gentamicin in order to eliminate non-adherent bacteria and incubated in medium overnight at 37°C. At 22 h post-infection, TEER values were still low for the monolayers infected at higher titers (298.8 ± 17.5 Ω.cm2 and 146.3 ± 7.4 Ω.cm2 for MOIs of 400:1 and 4000:1, respectively). In contrast, at a bacterial MOI of 40:1 we observed a substantial recovery in TEER, although still significantly lower than baseline (1235.3 ± 71.4 Ω.cm2 compared to a baseline value of 1487 ± 75.0 Ω.cm2) (Figure 1A). Taken together, these data demonstrate that S. Typhi alters Caco2 monolayer barrier function in a dose-dependent manner. Interestingly, the removal of bacteria allows the cells to slowly recover and counteract the adverse effect caused by the pathogen. This process apparently starts earlier for lower bacterial loads, presumably because the damage to the barrier function is less severe.


In vitro Intestinal Mucosal Epithelial Responses to Wild-Type Salmonella Typhi and Attenuated Typhoid Vaccines.

Fiorentino M, Lammers KM, Levine MM, Sztein MB, Fasano A - Front Immunol (2013)

Trans-epithelial electrical resistance (TEER) responses of CaCo2 cell monolayers to wild-type S. Typhi, HK bacteria, and culture supernatants. (A) TEER changes upon infection with wild-type S. Typhi at different MOIs. (B) TEER in HK bacteria and culture supernatants (Cond. Media) treated monolayers. Data are expressed as means ± SEM for triplicate samples for all conditions tested. These results are representative of three experiments with similar results. #Denotes p < 0.001 of S. Typhi strains over t = 0 (ANOVA).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3569575&req=5

Figure 1: Trans-epithelial electrical resistance (TEER) responses of CaCo2 cell monolayers to wild-type S. Typhi, HK bacteria, and culture supernatants. (A) TEER changes upon infection with wild-type S. Typhi at different MOIs. (B) TEER in HK bacteria and culture supernatants (Cond. Media) treated monolayers. Data are expressed as means ± SEM for triplicate samples for all conditions tested. These results are representative of three experiments with similar results. #Denotes p < 0.001 of S. Typhi strains over t = 0 (ANOVA).
Mentions: To investigate the effects of S. Typhi on mucosal barrier integrity, we infected Caco2 monolayers with S. Typhi at different MOIs. Since modulation and/or disruption of epithelial barrier function can be measured by changes in TEER, we used this technique to monitor alterations in mucosal permeability caused by the bacteria. As shown in Figure 1A we found that wild-type S. Typhi induced a decrease in TEER in the monolayer in a dose-dependent manner. All inoculation ratios used (MOIs of 40:1, 400:1, and 4000:1 bacteria:cell ratios, respectively) caused a significant drop in TEER [from 1147.0 ± 21.2 Ω.cm2 at baseline to 804.1 ± 37.5 Ω.cm2, 318.7 ± 38.2 Ω.cm2, and 252.6 ± 8.1 Ω.cm2, respectively] as early as 2 h post-infection. The decrease in TEER was even more dramatic at 4 h post-infection with TEER values of 527.6 ± 34.9 Ω.cm2, 206 ± 15.5 Ω.cm2, and 170.1 ± 1.6 Ω.cm2, respectively compared to baseline (1185.2 ± 40.0 Ω.cm2). At 4 h, bacteria were removed and monolayers were treated with gentamicin in order to eliminate non-adherent bacteria and incubated in medium overnight at 37°C. At 22 h post-infection, TEER values were still low for the monolayers infected at higher titers (298.8 ± 17.5 Ω.cm2 and 146.3 ± 7.4 Ω.cm2 for MOIs of 400:1 and 4000:1, respectively). In contrast, at a bacterial MOI of 40:1 we observed a substantial recovery in TEER, although still significantly lower than baseline (1235.3 ± 71.4 Ω.cm2 compared to a baseline value of 1487 ± 75.0 Ω.cm2) (Figure 1A). Taken together, these data demonstrate that S. Typhi alters Caco2 monolayer barrier function in a dose-dependent manner. Interestingly, the removal of bacteria allows the cells to slowly recover and counteract the adverse effect caused by the pathogen. This process apparently starts earlier for lower bacterial loads, presumably because the damage to the barrier function is less severe.

Bottom Line: Typhi exhibited alterations in the organization of tight junctions, increased paracellular permeability, and a rapid decrease in Trans-Epithelial Electrical Resistance as early as 4 h post-exposure.We conclude that wild-type S.Typhi causes marked transient alterations of the intestinal mucosa that are more pronounced than those observed with Ty21a or new generation attenuated typhoid vaccine candidates.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Mucosal Biology Research Center, University of Maryland School of Medicine Baltimore, MD, USA.

ABSTRACT
Typhoid fever, caused by S. Typhi, is responsible for approximately 200,000 deaths per year worldwide. Little information is available regarding epithelium-bacterial interactions in S. Typhi infection. We have evaluated in vitro the effects of wild-type S. Typhi, the licensed Ty21a typhoid vaccine and the leading strains CVD 908-htrA and CVD 909 vaccine candidates on intestinal barrier function and immune response. Caco2 monolayers infected with wild-type S. Typhi exhibited alterations in the organization of tight junctions, increased paracellular permeability, and a rapid decrease in Trans-Epithelial Electrical Resistance as early as 4 h post-exposure. S. Typhi triggered the secretion of interleukin (IL)-8 and IL-6. Caco2 cells infected with the attenuated strains exhibited a milder pro-inflammatory response with minimal disruption of the barrier integrity. We conclude that wild-type S. Typhi causes marked transient alterations of the intestinal mucosa that are more pronounced than those observed with Ty21a or new generation attenuated typhoid vaccine candidates.

No MeSH data available.


Related in: MedlinePlus