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Mannose-binding lectin-deficient mice are susceptible to infection with Staphylococcus aureus.

Shi L, Takahashi K, Dundee J, Shahroor-Karni S, Thiel S, Jensenius JC, Gad F, Hamblin MR, Sastry KN, Ezekowitz RA - J. Exp. Med. (2004)

Bottom Line: The mannose-binding lectin (MBL, also known as mannose-binding protein) is an oligomeric serum molecule that recognizes carbohydrates decorating a broad range of infectious agents including S. aureus.Circumstantial evidence in vitro and in vivo suggests that MBL plays a key role in first line host defense.Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, JRG 1402, Boston, MA 02114, USA.

ABSTRACT
Gram-positive organisms like Staphylococcus aureus are a major cause of morbidity and mortality worldwide. Humoral response molecules together with phagocytes play a role in host responses to S. aureus. The mannose-binding lectin (MBL, also known as mannose-binding protein) is an oligomeric serum molecule that recognizes carbohydrates decorating a broad range of infectious agents including S. aureus. Circumstantial evidence in vitro and in vivo suggests that MBL plays a key role in first line host defense. We tested this contention directly in vivo by generating mice that were devoid of all MBL activity. We found that 100% of MBL- mice died 48 h after exposure to an intravenous inoculation of S. aureus compared with 45% mortality in wild-type mice. Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus. Our study provides direct evidence that MBL plays a key role in restricting the complications associated with S. aureus infection in mice and raises the idea that the MBL gene may act as a disease susceptibility gene against staphylococci infections in humans.

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Increased S. aureus infection in MBL- mice and rescued MBL complement pathway by rhMBL in MBL- mice. (a) In vivo imaging of mice at 48 h after inoculation of the biolumi-S. aureus was performed as described in Materials and Methods. Representative pictures from WT, MBL-, and MBL- mice that were reconstituted with rhMBL (MBL  plus rhMBL) are shown. (b) Increased level of bacteria in organs from MBL- mice. Organs were harvested at 96 h after the infection with biolumi-S. Aureus and bacterial load was measured as described in Materials and Methods. Bars indicate mean ± SD. Numbers of mice used: WT, 8; MBL-, 7; MBL- plus rhMBL, 7. (c) MBL complement pathway activity before and after S. aureus CP5 infection. Plasma was collected at 4 d before as a base line and 4 d after S. aureus inoculation and analyzed for C4 deposition activity on mannan as described in Materials and Methods. Numbers of mice used before infection: WT, 12; MBL-, 19. Numbers of mice used after infection: WT, 12; MBL-, 10; MBL- plus rhMBL, 9. Two experiments were combined. Bars indicate mean ± SD. *, P = 0.002.
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fig6: Increased S. aureus infection in MBL- mice and rescued MBL complement pathway by rhMBL in MBL- mice. (a) In vivo imaging of mice at 48 h after inoculation of the biolumi-S. aureus was performed as described in Materials and Methods. Representative pictures from WT, MBL-, and MBL- mice that were reconstituted with rhMBL (MBL plus rhMBL) are shown. (b) Increased level of bacteria in organs from MBL- mice. Organs were harvested at 96 h after the infection with biolumi-S. Aureus and bacterial load was measured as described in Materials and Methods. Bars indicate mean ± SD. Numbers of mice used: WT, 8; MBL-, 7; MBL- plus rhMBL, 7. (c) MBL complement pathway activity before and after S. aureus CP5 infection. Plasma was collected at 4 d before as a base line and 4 d after S. aureus inoculation and analyzed for C4 deposition activity on mannan as described in Materials and Methods. Numbers of mice used before infection: WT, 12; MBL-, 19. Numbers of mice used after infection: WT, 12; MBL-, 10; MBL- plus rhMBL, 9. Two experiments were combined. Bars indicate mean ± SD. *, P = 0.002.

Mentions: The role of MBL in restricting tissue infection as it developed in the peritoneal cavity was evaluated. We adapted a modified rat infection model of S. aureus (57) to mice by administering the bacteria i.p. to achieve a slower seeding into the blood and tissues. In this way we could assess the role of MBL in combating infection in inflamed body cavities. Bacteremia and abscess formation were evaluated at various time points up to 10 d after i.p. inoculation of S. aureus ranging between 4 × 105 and 4 × 107 CFU/mouse. Even the highest dose of bacterial inoculation did not show difference in survival between WT, MBL-A KO, and MBL- mice. We chose a dose of 2 × 106 CFU/mouse and compared abscess formation in WT, MBL-A KO, and MBL- mice. There was no abscess formation in organs that we examined in any of the mice tested (Fig. 6). We did not test MBL-C KO mice as we assumed that they would be similar to MBL-A KO mice based on equivalence of MBL-A– and MBL-C–dependent complement pathway activity in the serum (Fig. 1 e). Of note, MBL is detectable in the peritoneal cavity of WT mice within hours of an inflammatory challenge (unpublished data).


Mannose-binding lectin-deficient mice are susceptible to infection with Staphylococcus aureus.

Shi L, Takahashi K, Dundee J, Shahroor-Karni S, Thiel S, Jensenius JC, Gad F, Hamblin MR, Sastry KN, Ezekowitz RA - J. Exp. Med. (2004)

Increased S. aureus infection in MBL- mice and rescued MBL complement pathway by rhMBL in MBL- mice. (a) In vivo imaging of mice at 48 h after inoculation of the biolumi-S. aureus was performed as described in Materials and Methods. Representative pictures from WT, MBL-, and MBL- mice that were reconstituted with rhMBL (MBL  plus rhMBL) are shown. (b) Increased level of bacteria in organs from MBL- mice. Organs were harvested at 96 h after the infection with biolumi-S. Aureus and bacterial load was measured as described in Materials and Methods. Bars indicate mean ± SD. Numbers of mice used: WT, 8; MBL-, 7; MBL- plus rhMBL, 7. (c) MBL complement pathway activity before and after S. aureus CP5 infection. Plasma was collected at 4 d before as a base line and 4 d after S. aureus inoculation and analyzed for C4 deposition activity on mannan as described in Materials and Methods. Numbers of mice used before infection: WT, 12; MBL-, 19. Numbers of mice used after infection: WT, 12; MBL-, 10; MBL- plus rhMBL, 9. Two experiments were combined. Bars indicate mean ± SD. *, P = 0.002.
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fig6: Increased S. aureus infection in MBL- mice and rescued MBL complement pathway by rhMBL in MBL- mice. (a) In vivo imaging of mice at 48 h after inoculation of the biolumi-S. aureus was performed as described in Materials and Methods. Representative pictures from WT, MBL-, and MBL- mice that were reconstituted with rhMBL (MBL plus rhMBL) are shown. (b) Increased level of bacteria in organs from MBL- mice. Organs were harvested at 96 h after the infection with biolumi-S. Aureus and bacterial load was measured as described in Materials and Methods. Bars indicate mean ± SD. Numbers of mice used: WT, 8; MBL-, 7; MBL- plus rhMBL, 7. (c) MBL complement pathway activity before and after S. aureus CP5 infection. Plasma was collected at 4 d before as a base line and 4 d after S. aureus inoculation and analyzed for C4 deposition activity on mannan as described in Materials and Methods. Numbers of mice used before infection: WT, 12; MBL-, 19. Numbers of mice used after infection: WT, 12; MBL-, 10; MBL- plus rhMBL, 9. Two experiments were combined. Bars indicate mean ± SD. *, P = 0.002.
Mentions: The role of MBL in restricting tissue infection as it developed in the peritoneal cavity was evaluated. We adapted a modified rat infection model of S. aureus (57) to mice by administering the bacteria i.p. to achieve a slower seeding into the blood and tissues. In this way we could assess the role of MBL in combating infection in inflamed body cavities. Bacteremia and abscess formation were evaluated at various time points up to 10 d after i.p. inoculation of S. aureus ranging between 4 × 105 and 4 × 107 CFU/mouse. Even the highest dose of bacterial inoculation did not show difference in survival between WT, MBL-A KO, and MBL- mice. We chose a dose of 2 × 106 CFU/mouse and compared abscess formation in WT, MBL-A KO, and MBL- mice. There was no abscess formation in organs that we examined in any of the mice tested (Fig. 6). We did not test MBL-C KO mice as we assumed that they would be similar to MBL-A KO mice based on equivalence of MBL-A– and MBL-C–dependent complement pathway activity in the serum (Fig. 1 e). Of note, MBL is detectable in the peritoneal cavity of WT mice within hours of an inflammatory challenge (unpublished data).

Bottom Line: The mannose-binding lectin (MBL, also known as mannose-binding protein) is an oligomeric serum molecule that recognizes carbohydrates decorating a broad range of infectious agents including S. aureus.Circumstantial evidence in vitro and in vivo suggests that MBL plays a key role in first line host defense.Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Developmental Immunology, Department of Pediatrics, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, JRG 1402, Boston, MA 02114, USA.

ABSTRACT
Gram-positive organisms like Staphylococcus aureus are a major cause of morbidity and mortality worldwide. Humoral response molecules together with phagocytes play a role in host responses to S. aureus. The mannose-binding lectin (MBL, also known as mannose-binding protein) is an oligomeric serum molecule that recognizes carbohydrates decorating a broad range of infectious agents including S. aureus. Circumstantial evidence in vitro and in vivo suggests that MBL plays a key role in first line host defense. We tested this contention directly in vivo by generating mice that were devoid of all MBL activity. We found that 100% of MBL- mice died 48 h after exposure to an intravenous inoculation of S. aureus compared with 45% mortality in wild-type mice. Furthermore, we demonstrated that neutrophils and MBL are required to limit intraperitoneal infection with S. aureus. Our study provides direct evidence that MBL plays a key role in restricting the complications associated with S. aureus infection in mice and raises the idea that the MBL gene may act as a disease susceptibility gene against staphylococci infections in humans.

Show MeSH
Related in: MedlinePlus