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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: 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.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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Lethal challenges with clinical isolates and ATCC strains of B. cereus.Mice were intraperitoneally administered with clinical isolates and ATCC strains of B. cereus (3×108 CFU/mouse). Clinical isolates; JMU-06B-31 (•), JMU-06B-35 (▪), and JMU-06B-1 (▴). ATCC strains; ATCC21928 (□), ATCC31429 (○), and ATCC6464 (△). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. B) The microorganisms in the blood of mice about 12 h after the administration of various strains were cultured on Luria Broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments. ND: not detected.
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pone-0038054-g001: Lethal challenges with clinical isolates and ATCC strains of B. cereus.Mice were intraperitoneally administered with clinical isolates and ATCC strains of B. cereus (3×108 CFU/mouse). Clinical isolates; JMU-06B-31 (•), JMU-06B-35 (▪), and JMU-06B-1 (▴). ATCC strains; ATCC21928 (□), ATCC31429 (○), and ATCC6464 (△). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. B) The microorganisms in the blood of mice about 12 h after the administration of various strains were cultured on Luria Broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments. ND: not detected.

Mentions: To investigate if B. cereus JMU-06B-31 and JMU-06B-1, isolated from a patient with septicemia, and JMU-06B-35, isolated from a patient with endophthalmitis, grow in mice in vivo, six- to eight-week old male wild-type mice of the ICR mice were each injected intraperitoneally with 5×108 CFU of the clinical isolates or ATCC21928, ATCC31429, and ATCC6464 isolated from soil. Mice administered with the clinical isolates began to die after 12 h, and all mice died within 30 h of the administration (Fig. 1A). Mice injected with ATCC21928, ATCC31429, and ATCC6464 did not die within 100 h (Fig. 1A). The number of microorganisms in the blood of mice about 12 h after the administration of JMU-06B-31, JMU-06B-35, and JMU-06B-1 was 300–400 CFU/100 µL, whereas the ATCC strains were not detected in blood (Fig. 1B).


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)

Lethal challenges with clinical isolates and ATCC strains of B. cereus.Mice were intraperitoneally administered with clinical isolates and ATCC strains of B. cereus (3×108 CFU/mouse). Clinical isolates; JMU-06B-31 (•), JMU-06B-35 (▪), and JMU-06B-1 (▴). ATCC strains; ATCC21928 (□), ATCC31429 (○), and ATCC6464 (△). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. B) The microorganisms in the blood of mice about 12 h after the administration of various strains were cultured on Luria Broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments. ND: not detected.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0038054-g001: Lethal challenges with clinical isolates and ATCC strains of B. cereus.Mice were intraperitoneally administered with clinical isolates and ATCC strains of B. cereus (3×108 CFU/mouse). Clinical isolates; JMU-06B-31 (•), JMU-06B-35 (▪), and JMU-06B-1 (▴). ATCC strains; ATCC21928 (□), ATCC31429 (○), and ATCC6464 (△). A) Mice were monitored every five hours after the injection. The duration of the experiment was set at 100 h. B) The microorganisms in the blood of mice about 12 h after the administration of various strains were cultured on Luria Broth agar plates. Values represent the mean ± SEM; n = 5 independent experiments. ND: not detected.
Mentions: To investigate if B. cereus JMU-06B-31 and JMU-06B-1, isolated from a patient with septicemia, and JMU-06B-35, isolated from a patient with endophthalmitis, grow in mice in vivo, six- to eight-week old male wild-type mice of the ICR mice were each injected intraperitoneally with 5×108 CFU of the clinical isolates or ATCC21928, ATCC31429, and ATCC6464 isolated from soil. Mice administered with the clinical isolates began to die after 12 h, and all mice died within 30 h of the administration (Fig. 1A). Mice injected with ATCC21928, ATCC31429, and ATCC6464 did not die within 100 h (Fig. 1A). The number of microorganisms in the blood of mice about 12 h after the administration of JMU-06B-31, JMU-06B-35, and JMU-06B-1 was 300–400 CFU/100 µL, whereas the ATCC strains were not detected in blood (Fig. 1B).

Bottom Line: 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.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