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A potential new pathway for Staphylococcus aureus dissemination: the silent survival of S. aureus phagocytosed by human monocyte-derived macrophages.

Kubica M, Guzik K, Koziel J, Zarebski M, Richter W, Gajkowska B, Golda A, Maciag-Gudowska A, Brix K, Shaw L, Foster T, Potempa J - PLoS ONE (2008)

Bottom Line: In particular alpha-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages.Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types.S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland. staphaureus@gmail.com

ABSTRACT
Although considered to be an extracellular pathogen, Staphylococcus aureus is able to invade a variety of mammalian, non-professional phagocytes and can also survive engulfment by professional phagocytes such as neutrophils and monocytes. In both of these cell types S. aureus promptly escapes from the endosomes/phagosomes and proliferates within the cytoplasm, which quickly leads to host cell death. In this report we show that S. aureus interacted with human monocyte-derived macrophages in a very different way to those of other mammalian cells. Upon phagocytosis by macrophages, S. aureus persisted intracellularly in vacuoles for 3-4 days before escaping into the cytoplasm and causing host cell lysis. Until the point of host cell lysis the infected macrophages showed no signs of apoptosis or necrosis and were functional. They were able to eliminate intracellular staphylococci if prestimulated with interferon-gamma at concentrations equivalent to human therapeutic doses. S. aureus survival was dependent on the alternative sigma factor B as well as the global regulator agr, but not SarA. Furthermore, isogenic mutants deficient in alpha-toxin, the metalloprotease aureolysin, protein A, and sortase A were efficiently killed by macrophages upon phagocytosis, although with different kinetics. In particular alpha-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages. Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types. S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection.

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Related in: MedlinePlus

An α-hemolysin mutant of S. aureus strain Newman is efficiently killed in phago(lyso)somes within two days of phagocytosis.Intracellular persistence of S. aureus was determined as described in the legend of Fig. 3A. Bars represent mean CFU values ±SD and are representative of at least three separate experiments, performed in triplicate, using hMDMs derived from different donors. An electron microphotograph of infected hMDMs was obtained 1 day post-phagocytosis and shows partially (white arrows) and totally degraded (black arrows) bacterial cells inside tight vacuoles. At this time point some apparently intact bacterial cells are also present (black arrowheads). Magnification: x32,500. The photograph presented is a representative of a minimum of 20 fields observed.
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pone-0001409-g007: An α-hemolysin mutant of S. aureus strain Newman is efficiently killed in phago(lyso)somes within two days of phagocytosis.Intracellular persistence of S. aureus was determined as described in the legend of Fig. 3A. Bars represent mean CFU values ±SD and are representative of at least three separate experiments, performed in triplicate, using hMDMs derived from different donors. An electron microphotograph of infected hMDMs was obtained 1 day post-phagocytosis and shows partially (white arrows) and totally degraded (black arrows) bacterial cells inside tight vacuoles. At this time point some apparently intact bacterial cells are also present (black arrowheads). Magnification: x32,500. The photograph presented is a representative of a minimum of 20 fields observed.

Mentions: SarA and agr differentially regulate the expression of virulence factors, especially surface-associated proteins (MSCRAMMs) and secreted enzymes [8]. In addition, it has previously been established that α-hemolysin is vital for the escape of S. aureus from phagosomes into the cytoplasm of infected, non-professional phagocytes [15], [62]. Therefore we examined the effects of inactivation of hla (Fig. 7), the major extracellular proteases (aureolysin, the V8 protease and staphopain B), and surface adhesins (via a sortase A mutant) (Fig. 8) on the survival of S. aureus Newman phagocytosed by hMDMs.


A potential new pathway for Staphylococcus aureus dissemination: the silent survival of S. aureus phagocytosed by human monocyte-derived macrophages.

Kubica M, Guzik K, Koziel J, Zarebski M, Richter W, Gajkowska B, Golda A, Maciag-Gudowska A, Brix K, Shaw L, Foster T, Potempa J - PLoS ONE (2008)

An α-hemolysin mutant of S. aureus strain Newman is efficiently killed in phago(lyso)somes within two days of phagocytosis.Intracellular persistence of S. aureus was determined as described in the legend of Fig. 3A. Bars represent mean CFU values ±SD and are representative of at least three separate experiments, performed in triplicate, using hMDMs derived from different donors. An electron microphotograph of infected hMDMs was obtained 1 day post-phagocytosis and shows partially (white arrows) and totally degraded (black arrows) bacterial cells inside tight vacuoles. At this time point some apparently intact bacterial cells are also present (black arrowheads). Magnification: x32,500. The photograph presented is a representative of a minimum of 20 fields observed.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169301&req=5

pone-0001409-g007: An α-hemolysin mutant of S. aureus strain Newman is efficiently killed in phago(lyso)somes within two days of phagocytosis.Intracellular persistence of S. aureus was determined as described in the legend of Fig. 3A. Bars represent mean CFU values ±SD and are representative of at least three separate experiments, performed in triplicate, using hMDMs derived from different donors. An electron microphotograph of infected hMDMs was obtained 1 day post-phagocytosis and shows partially (white arrows) and totally degraded (black arrows) bacterial cells inside tight vacuoles. At this time point some apparently intact bacterial cells are also present (black arrowheads). Magnification: x32,500. The photograph presented is a representative of a minimum of 20 fields observed.
Mentions: SarA and agr differentially regulate the expression of virulence factors, especially surface-associated proteins (MSCRAMMs) and secreted enzymes [8]. In addition, it has previously been established that α-hemolysin is vital for the escape of S. aureus from phagosomes into the cytoplasm of infected, non-professional phagocytes [15], [62]. Therefore we examined the effects of inactivation of hla (Fig. 7), the major extracellular proteases (aureolysin, the V8 protease and staphopain B), and surface adhesins (via a sortase A mutant) (Fig. 8) on the survival of S. aureus Newman phagocytosed by hMDMs.

Bottom Line: In particular alpha-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages.Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types.S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland. staphaureus@gmail.com

ABSTRACT
Although considered to be an extracellular pathogen, Staphylococcus aureus is able to invade a variety of mammalian, non-professional phagocytes and can also survive engulfment by professional phagocytes such as neutrophils and monocytes. In both of these cell types S. aureus promptly escapes from the endosomes/phagosomes and proliferates within the cytoplasm, which quickly leads to host cell death. In this report we show that S. aureus interacted with human monocyte-derived macrophages in a very different way to those of other mammalian cells. Upon phagocytosis by macrophages, S. aureus persisted intracellularly in vacuoles for 3-4 days before escaping into the cytoplasm and causing host cell lysis. Until the point of host cell lysis the infected macrophages showed no signs of apoptosis or necrosis and were functional. They were able to eliminate intracellular staphylococci if prestimulated with interferon-gamma at concentrations equivalent to human therapeutic doses. S. aureus survival was dependent on the alternative sigma factor B as well as the global regulator agr, but not SarA. Furthermore, isogenic mutants deficient in alpha-toxin, the metalloprotease aureolysin, protein A, and sortase A were efficiently killed by macrophages upon phagocytosis, although with different kinetics. In particular alpha-toxin was a key effector molecule that was essential for S. aureus intracellular survival in macrophages. Together, our data indicate that the ability of S. aureus to survive phagocytosis by macrophages is determined by multiple virulence factors in a way that differs considerably from its interactions with other cell types. S. aureus persists inside macrophages for several days without affecting the viability of these mobile cells which may serve as vehicles for the dissemination of infection.

Show MeSH
Related in: MedlinePlus