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Role of sphingomyelinase in infectious diseases caused by Bacillus cereus.

Oda M, Hashimoto M, Takahashi M, Ohmae Y, Seike S, Kato R, Fujita A, Tsuge H, Nagahama M, Ochi S, Sasahara T, Hayashi S, Hirai Y, Sakurai J - PLoS ONE (2012)

Bottom Line: Treatment of mouse macrophages with Bc-SMase resulted in a reduction in the generation of H(2)O(2) and phagocytosis of macrophages induced by peptidoglycan (PGN), but no effect on the release of TNF-α and little release of LDH under our experimental conditions.A photobleaching analysis suggested that the cells treated with Bc-SMase exhibited a reduction in membrane fluidity.The results suggest that Bc-SMase is essential for the hydrolysis of SM in membranes, leading to a reduction in phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, Japan.

ABSTRACT
Bacillus cereus (B. cereus) is a pathogen in opportunistic infections. Here we show that Bacillus cereus sphingomyelinase (Bc-SMase) is a virulence factor for septicemia. Clinical isolates produced large amounts of Bc-SMase, grew in vivo, and caused death among mice, but ATCC strains isolated from soil did not. A transformant of the ATCC strain carrying a recombinant plasmid containing the Bc-SMase gene grew in vivo, but that with the gene for E53A, which has little enzymatic activity, did not. Administration of an anti-Bc-SMase antibody and immunization against Bc-SMase prevented death caused by the clinical isolates, showing that Bc-SMase plays an important role in the diseases caused by B. cereus. Treatment of mouse macrophages with Bc-SMase resulted in a reduction in the generation of H(2)O(2) and phagocytosis of macrophages induced by peptidoglycan (PGN), but no effect on the release of TNF-α and little release of LDH under our experimental conditions. Confocal laser microscopy showed that the treatment of mouse macrophages with Bc-SMase resulted in the formation of ceramide-rich domains. A photobleaching analysis suggested that the cells treated with Bc-SMase exhibited a reduction in membrane fluidity. The results suggest that Bc-SMase is essential for the hydrolysis of SM in membranes, leading to a reduction in phagocytosis.

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Effect of Bc-SMase on the infection with B. cereus or B. subtilis.Mice received various concentrations of Bc-SMase and B. cereus (ATCC21928, 5×107 CFU/mouse). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. ○, B. cereus; □, 1.0 µg Bc-SMase; △, 5.0 µg Bc-SMase; ▴, 0.1 µg Bc-SMase + B. cereus; •, 1.0 µg Bc-SMase + B. cereus; ▪, 5.0 µg Bc-SMase + B. cereus. B) B. cereus in blood was cultured on Luria broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments.
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pone-0038054-g004: Effect of Bc-SMase on the infection with B. cereus or B. subtilis.Mice received various concentrations of Bc-SMase and B. cereus (ATCC21928, 5×107 CFU/mouse). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. ○, B. cereus; □, 1.0 µg Bc-SMase; △, 5.0 µg Bc-SMase; ▴, 0.1 µg Bc-SMase + B. cereus; •, 1.0 µg Bc-SMase + B. cereus; ▪, 5.0 µg Bc-SMase + B. cereus. B) B. cereus in blood was cultured on Luria broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments.

Mentions: To investigate the role of Bc-SMase in B. cereus infections, we examined the effect of Bc-SMase on B. cereus-induced death in mice. The animals were intraperitoneally injected with mixtures of ATCC21928 (5.0×107 CFU/mouse), which did not produce Bc-SMase in the culture supernatants, and various concentrations of Bc-SMase. As shown in Fig. 4A, the increase in the rate of death was dependent on the dose of Bc-SMase above 1.0 µg/mouse. On administration of ATCC21928 and 5.0 µg of Bc-SMase, the death rate was 100% within 30 h (Fig. 4A). Mice injected with ATCC21928 or Bc-SMase alone survived after 100 h under the experimental conditions (Fig. 4A). In addition, the number of microorganisms in blood 12 h after the administration of the mixture of ATCC21928 and 1.0 or 5.0 µg of Bc-SMase was 50–100 and 300–400 CFU/100 µl, respectively (Fig. 4B). On the other hand, the administration of ATCC21928 with PCPLC (5.0 µg/mouse) or PIPLC (5.0 µg/mouse) resulted in no death under the conditions (data not shown).


Role of sphingomyelinase in infectious diseases caused by Bacillus cereus.

Oda M, Hashimoto M, Takahashi M, Ohmae Y, Seike S, Kato R, Fujita A, Tsuge H, Nagahama M, Ochi S, Sasahara T, Hayashi S, Hirai Y, Sakurai J - PLoS ONE (2012)

Effect of Bc-SMase on the infection with B. cereus or B. subtilis.Mice received various concentrations of Bc-SMase and B. cereus (ATCC21928, 5×107 CFU/mouse). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. ○, B. cereus; □, 1.0 µg Bc-SMase; △, 5.0 µg Bc-SMase; ▴, 0.1 µg Bc-SMase + B. cereus; •, 1.0 µg Bc-SMase + B. cereus; ▪, 5.0 µg Bc-SMase + B. cereus. B) B. cereus in blood was cultured on Luria broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368938&req=5

pone-0038054-g004: Effect of Bc-SMase on the infection with B. cereus or B. subtilis.Mice received various concentrations of Bc-SMase and B. cereus (ATCC21928, 5×107 CFU/mouse). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. ○, B. cereus; □, 1.0 µg Bc-SMase; △, 5.0 µg Bc-SMase; ▴, 0.1 µg Bc-SMase + B. cereus; •, 1.0 µg Bc-SMase + B. cereus; ▪, 5.0 µg Bc-SMase + B. cereus. B) B. cereus in blood was cultured on Luria broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments.
Mentions: To investigate the role of Bc-SMase in B. cereus infections, we examined the effect of Bc-SMase on B. cereus-induced death in mice. The animals were intraperitoneally injected with mixtures of ATCC21928 (5.0×107 CFU/mouse), which did not produce Bc-SMase in the culture supernatants, and various concentrations of Bc-SMase. As shown in Fig. 4A, the increase in the rate of death was dependent on the dose of Bc-SMase above 1.0 µg/mouse. On administration of ATCC21928 and 5.0 µg of Bc-SMase, the death rate was 100% within 30 h (Fig. 4A). Mice injected with ATCC21928 or Bc-SMase alone survived after 100 h under the experimental conditions (Fig. 4A). In addition, the number of microorganisms in blood 12 h after the administration of the mixture of ATCC21928 and 1.0 or 5.0 µg of Bc-SMase was 50–100 and 300–400 CFU/100 µl, respectively (Fig. 4B). On the other hand, the administration of ATCC21928 with PCPLC (5.0 µg/mouse) or PIPLC (5.0 µg/mouse) resulted in no death under the conditions (data not shown).

Bottom Line: Treatment of mouse macrophages with Bc-SMase resulted in a reduction in the generation of H(2)O(2) and phagocytosis of macrophages induced by peptidoglycan (PGN), but no effect on the release of TNF-α and little release of LDH under our experimental conditions.A photobleaching analysis suggested that the cells treated with Bc-SMase exhibited a reduction in membrane fluidity.The results suggest that Bc-SMase is essential for the hydrolysis of SM in membranes, leading to a reduction in phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima, Japan.

ABSTRACT
Bacillus cereus (B. cereus) is a pathogen in opportunistic infections. Here we show that Bacillus cereus sphingomyelinase (Bc-SMase) is a virulence factor for septicemia. Clinical isolates produced large amounts of Bc-SMase, grew in vivo, and caused death among mice, but ATCC strains isolated from soil did not. A transformant of the ATCC strain carrying a recombinant plasmid containing the Bc-SMase gene grew in vivo, but that with the gene for E53A, which has little enzymatic activity, did not. Administration of an anti-Bc-SMase antibody and immunization against Bc-SMase prevented death caused by the clinical isolates, showing that Bc-SMase plays an important role in the diseases caused by B. cereus. Treatment of mouse macrophages with Bc-SMase resulted in a reduction in the generation of H(2)O(2) and phagocytosis of macrophages induced by peptidoglycan (PGN), but no effect on the release of TNF-α and little release of LDH under our experimental conditions. Confocal laser microscopy showed that the treatment of mouse macrophages with Bc-SMase resulted in the formation of ceramide-rich domains. A photobleaching analysis suggested that the cells treated with Bc-SMase exhibited a reduction in membrane fluidity. The results suggest that Bc-SMase is essential for the hydrolysis of SM in membranes, leading to a reduction in phagocytosis.

Show MeSH
Related in: MedlinePlus