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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

S. Typhi attenuated strains induce secretion of IL-6. IL-6 secreted by Caco2 cells infected with vaccine candidates CVD 908-htrA and CVD 909 applied at different bacterial loads, conditioned media, and the wild-type strain, as positive control. Values shown represent the mean ± SEM of three independent assays. #p < 0.05 over uninfected; ***p < 0.001, **p < 0.01, *p < 0.05 for comparisons between wild-type S. Typhi and mutant strains applied at the same titer (ANOVA).
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Figure 10: S. Typhi attenuated strains induce secretion of IL-6. IL-6 secreted by Caco2 cells infected with vaccine candidates CVD 908-htrA and CVD 909 applied at different bacterial loads, conditioned media, and the wild-type strain, as positive control. Values shown represent the mean ± SEM of three independent assays. #p < 0.05 over uninfected; ***p < 0.001, **p < 0.01, *p < 0.05 for comparisons between wild-type S. Typhi and mutant strains applied at the same titer (ANOVA).

Mentions: IL-8 secreted by Caco2 monolayers upon infection with Ty21a strain (MOI 400:1), was ∼50 and 100-fold greater than the uninfected control in the apical and basolateral sides, respectively (Figure 9D). Ty21a elicited a reduced IL-8 release compared to wild-type S. Typhi, with a significant difference in the basal compartment. At a higher MOI, significant difference was observed between wild-type and Ty21a only for IL-8 amounts released apically. Of note, in our in vitro system we did not observe any substantial difference in the ability of Ty21a to elicit IL-8 secretion when Ty21a was grown in the absence or presence of 0.05% galactose, a concentration which has been previously shown to allow complete LPS O-antigen synthesis without reducing the strain growth rate (Shi et al., 2010). As shown in Figure 10, IL-6 was secreted by all strains and at all conditions applied. IL-6 levels measured apically were significantly higher than uninfected cells for most of the strains and conditions except CM, CVD 908-htrA at a MOI of 40:1 and CVD 909 at MOIs of 40:1 and 400:1. On the basolateral surface IL-6 secretion levels appeared to be statistically higher than uninfected controls for wild-type S. Typhi and CVD 908-htrA applied at a MOI of 400:1 and S. Typhi applied at a MOI of 40:1. At the highest bacterial loads (MOIs 4000:1 and 400:1) we did not observe any significant difference in the level of IL-6 secretion between the wild-type strain and either vaccine candidate in both compartments; conversely, both CVD 908-htrA and CVD 909 applied at a MOI of 40:1 induced a basolateral secretion of IL-6 significantly lower than wild-type Salmonella. No statistical differences were observed between CVD 908-htrA and CVD 909 strains.


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)

S. Typhi attenuated strains induce secretion of IL-6. IL-6 secreted by Caco2 cells infected with vaccine candidates CVD 908-htrA and CVD 909 applied at different bacterial loads, conditioned media, and the wild-type strain, as positive control. Values shown represent the mean ± SEM of three independent assays. #p < 0.05 over uninfected; ***p < 0.001, **p < 0.01, *p < 0.05 for comparisons between wild-type S. Typhi and mutant strains applied at the same titer (ANOVA).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 10: S. Typhi attenuated strains induce secretion of IL-6. IL-6 secreted by Caco2 cells infected with vaccine candidates CVD 908-htrA and CVD 909 applied at different bacterial loads, conditioned media, and the wild-type strain, as positive control. Values shown represent the mean ± SEM of three independent assays. #p < 0.05 over uninfected; ***p < 0.001, **p < 0.01, *p < 0.05 for comparisons between wild-type S. Typhi and mutant strains applied at the same titer (ANOVA).
Mentions: IL-8 secreted by Caco2 monolayers upon infection with Ty21a strain (MOI 400:1), was ∼50 and 100-fold greater than the uninfected control in the apical and basolateral sides, respectively (Figure 9D). Ty21a elicited a reduced IL-8 release compared to wild-type S. Typhi, with a significant difference in the basal compartment. At a higher MOI, significant difference was observed between wild-type and Ty21a only for IL-8 amounts released apically. Of note, in our in vitro system we did not observe any substantial difference in the ability of Ty21a to elicit IL-8 secretion when Ty21a was grown in the absence or presence of 0.05% galactose, a concentration which has been previously shown to allow complete LPS O-antigen synthesis without reducing the strain growth rate (Shi et al., 2010). As shown in Figure 10, IL-6 was secreted by all strains and at all conditions applied. IL-6 levels measured apically were significantly higher than uninfected cells for most of the strains and conditions except CM, CVD 908-htrA at a MOI of 40:1 and CVD 909 at MOIs of 40:1 and 400:1. On the basolateral surface IL-6 secretion levels appeared to be statistically higher than uninfected controls for wild-type S. Typhi and CVD 908-htrA applied at a MOI of 400:1 and S. Typhi applied at a MOI of 40:1. At the highest bacterial loads (MOIs 4000:1 and 400:1) we did not observe any significant difference in the level of IL-6 secretion between the wild-type strain and either vaccine candidate in both compartments; conversely, both CVD 908-htrA and CVD 909 applied at a MOI of 40:1 induced a basolateral secretion of IL-6 significantly lower than wild-type Salmonella. No statistical differences were observed between CVD 908-htrA and CVD 909 strains.

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