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The Saccharomyces boulardii CNCM I-745 strain shows protective effects against the B. anthracis LT toxin.

Pontier-Bres R, Rampal P, Peyron JF, Munro P, Lemichez E, Czerucka D - Toxins (Basel) (2015)

Bottom Line: Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers.Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage.Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA.

View Article: PubMed Central - PubMed

Affiliation: Centre Scientifique de Monaco, Monaco 98000, Monaco.

ABSTRACT
The probiotic yeast Saccharomyces boulardii (S. boulardii) has been prescribed for the prophylaxis and treatment of several infectious diarrheal diseases. Gastrointestinal anthrax causes fatal systemic disease. In the present study, we investigated the protective effects conferred by Saccharomyces boulardii CNCM I-745 strain on polarized T84 columnar epithelial cells intoxicated by the lethal toxin (LT) of Bacillus anthracis. Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers. Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage. Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA. Our study highlights the potential of the S. boulardii CNCM I-745 strain as a prophylactic agent against the gastrointestinal form of anthrax.

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Actin cytoskeleton organization in T84 cells (upper) and HUVECs (down). Pictures show control cells (A); cells exposed to LT for 24 h (LT 24 h) (B); cells incubated with S. boulardii (ON) before LT addition for 24 h (C); and cells incubated with S. boulardii overnight (ON) as sole treatment (D). TRITC-conjugated phalloidin was used for F-actin labeling. Identical results were obtained at least in three independent experiments. Bar = 10 μm.
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toxins-07-04455-f001: Actin cytoskeleton organization in T84 cells (upper) and HUVECs (down). Pictures show control cells (A); cells exposed to LT for 24 h (LT 24 h) (B); cells incubated with S. boulardii (ON) before LT addition for 24 h (C); and cells incubated with S. boulardii overnight (ON) as sole treatment (D). TRITC-conjugated phalloidin was used for F-actin labeling. Identical results were obtained at least in three independent experiments. Bar = 10 μm.

Mentions: To evaluate inhibitors of the intoxication process, we took advantage of the massive actin cytoskeleton reorganization promoted by LT through MEK inhibition [24,25]. To begin, we tested whether S. boulardii treatment blocked cell intoxication due to LT. We tested the effect of the LT toxin on the actin cytoskeleton in T84 cells. Polarized monolayers of T84 cells were apically exposed to the LT toxin for 24 h, and the formation of stress cables was monitored by confocal microscopy. After 24 h of intoxication, LT induced stress fiber formation in the T84 cells compared with control cells (Figure 1A,B, T84). In contrast, when the cells were pretreated with S. boulardii for 15 h (S. b (ON)) before LT intoxication, we observed a limited effect on the reorganization of the actin cytoskeleton (Figure 1C, T84). We verified that overnight treatment of cells with S. boulardii alone had no effect (Figure 1D, T84). Next, we tested whether S. boulardii protected primary human umbilical vein endothelial cells (HUVECs) against intoxication. As previously shown, the treatment of HUVECs with LT for 24 h induced a strong remodeling of the actin cytoskeleton into stress fibers (Figure 1A,B, HUVEC). A manual quantification of cells with modified cytoskeleton organization revealed that 20% of the LT-treated cells contained thick actin cables, compared with 5.4% in control cells. In keeping with the above observations in epithelial cells, we measured a significant decrease in stress fiber formation in HUVECs pretreated with S. boulardii for 15 h before LT intoxication (Figure 1C, HUVEC). We verified that 15 h of cell treatment with S. boulardii alone had no effect on the actin cytoskeleton (Figure 1D, HUVEC). Treatment of cells with S. boulardii limits the cytotoxic effects of LT on actin organization.


The Saccharomyces boulardii CNCM I-745 strain shows protective effects against the B. anthracis LT toxin.

Pontier-Bres R, Rampal P, Peyron JF, Munro P, Lemichez E, Czerucka D - Toxins (Basel) (2015)

Actin cytoskeleton organization in T84 cells (upper) and HUVECs (down). Pictures show control cells (A); cells exposed to LT for 24 h (LT 24 h) (B); cells incubated with S. boulardii (ON) before LT addition for 24 h (C); and cells incubated with S. boulardii overnight (ON) as sole treatment (D). TRITC-conjugated phalloidin was used for F-actin labeling. Identical results were obtained at least in three independent experiments. Bar = 10 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4663514&req=5

toxins-07-04455-f001: Actin cytoskeleton organization in T84 cells (upper) and HUVECs (down). Pictures show control cells (A); cells exposed to LT for 24 h (LT 24 h) (B); cells incubated with S. boulardii (ON) before LT addition for 24 h (C); and cells incubated with S. boulardii overnight (ON) as sole treatment (D). TRITC-conjugated phalloidin was used for F-actin labeling. Identical results were obtained at least in three independent experiments. Bar = 10 μm.
Mentions: To evaluate inhibitors of the intoxication process, we took advantage of the massive actin cytoskeleton reorganization promoted by LT through MEK inhibition [24,25]. To begin, we tested whether S. boulardii treatment blocked cell intoxication due to LT. We tested the effect of the LT toxin on the actin cytoskeleton in T84 cells. Polarized monolayers of T84 cells were apically exposed to the LT toxin for 24 h, and the formation of stress cables was monitored by confocal microscopy. After 24 h of intoxication, LT induced stress fiber formation in the T84 cells compared with control cells (Figure 1A,B, T84). In contrast, when the cells were pretreated with S. boulardii for 15 h (S. b (ON)) before LT intoxication, we observed a limited effect on the reorganization of the actin cytoskeleton (Figure 1C, T84). We verified that overnight treatment of cells with S. boulardii alone had no effect (Figure 1D, T84). Next, we tested whether S. boulardii protected primary human umbilical vein endothelial cells (HUVECs) against intoxication. As previously shown, the treatment of HUVECs with LT for 24 h induced a strong remodeling of the actin cytoskeleton into stress fibers (Figure 1A,B, HUVEC). A manual quantification of cells with modified cytoskeleton organization revealed that 20% of the LT-treated cells contained thick actin cables, compared with 5.4% in control cells. In keeping with the above observations in epithelial cells, we measured a significant decrease in stress fiber formation in HUVECs pretreated with S. boulardii for 15 h before LT intoxication (Figure 1C, HUVEC). We verified that 15 h of cell treatment with S. boulardii alone had no effect on the actin cytoskeleton (Figure 1D, HUVEC). Treatment of cells with S. boulardii limits the cytotoxic effects of LT on actin organization.

Bottom Line: Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers.Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage.Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA.

View Article: PubMed Central - PubMed

Affiliation: Centre Scientifique de Monaco, Monaco 98000, Monaco.

ABSTRACT
The probiotic yeast Saccharomyces boulardii (S. boulardii) has been prescribed for the prophylaxis and treatment of several infectious diarrheal diseases. Gastrointestinal anthrax causes fatal systemic disease. In the present study, we investigated the protective effects conferred by Saccharomyces boulardii CNCM I-745 strain on polarized T84 columnar epithelial cells intoxicated by the lethal toxin (LT) of Bacillus anthracis. Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers. Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage. Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA. Our study highlights the potential of the S. boulardii CNCM I-745 strain as a prophylactic agent against the gastrointestinal form of anthrax.

Show MeSH
Related in: MedlinePlus