Phagocytosis of a bacterium, showing the formation of phagosome and phagolysosome
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs).[1]
A phagosome is formed by the fusion of the cell membrane around a microorganism, a senescent cell or an apoptotic cell. Phagosomes have membrane-bound proteins to recruit and fuse with lysosomes to form mature phagolysosomes. The lysosomes contain hydrolytic enzymes and reactive oxygen species (ROS) which kill and digest the pathogens. Phagosomes can also form in non-professional phagocytes, but they can only engulf a smaller range of particles, and do not contain ROS. The useful materials (e.g. amino acids) from the digested particles are moved into the cytosol, and waste is removed by exocytosis. Phagosome formation is crucial for tissue homeostasis and both innate and adaptive host defense against pathogens.
However, some bacteria can exploit phagocytosis as an invasion strategy. They either reproduce inside of the phagolysosome (e.g. Coxiella spp.)[2] or escape into the cytoplasm before the phagosome fuses with the lysosome (e.g. Rickettsia spp.).[3] Many Mycobacteria, including Mycobacterium tuberculosis[4][5] and Mycobacterium avium paratuberculosis,[6] can manipulate the host macrophage to prevent lysosomes from fusing with phagosomes and creating mature phagolysosomes. Such incomplete maturation of the phagosome maintains an environment favorable to the pathogens inside it.[7]
^Robinson & Babcock 1998, p. 187 harvnb error: no target: CITEREFRobinsonBabcock1998 (help) and Ernst & Stendahl 2006, pp. 7–10 harvnb error: no target: CITEREFErnstStendahl2006 (help)
^Hackstadt T, Williams JC (May 1981). "Biochemical stratagem for obligate parasitism of eukaryotic cells by Coxiella burnetii". Proceedings of the National Academy of Sciences of the United States of America. 78 (5): 3240–4. doi:10.1073/pnas.78.5.3240. PMC 319537. PMID 6942430.
^Winkler HH (1990). "Rickettsia Species (As Organisms)". Annual Review of Microbiology. 44: 131–153. doi:10.1146/annurev.micro.44.1.131. PMID 2252380.
^MacMicking JD, Taylor GA, McKinney JD (October 2003). "Immune control of tuberculosis by IFN-gamma-inducible LRG-47". Science. 302 (5645): 654–9. Bibcode:2003Sci...302..654M. doi:10.1126/science.1088063. PMID 14576437. S2CID 83944695.
^Vandal OH, Pierini LM, Schnappinger D, Nathan CF, Ehrt S (August 2008). "A membrane protein preserves intrabacterial pH in intraphagosomal Mycobacterium tuberculosis". Nature Medicine. 14 (8): 849–54. doi:10.1038/nm.1795. PMC 2538620. PMID 18641659.
^Kuehnel MP, Goethe R, Habermann A, Mueller E, Rohde M, Griffiths G, Valentin-Weigand P (August 2001). "Characterization of the intracellular survival of Mycobacterium avium ssp. paratuberculosis: phagosomal pH and fusogenicity in J774 macrophages compared with other mycobacteria". Cellular Microbiology. 3 (8): 551–66. doi:10.1046/j.1462-5822.2001.00139.x. PMID 11488816. S2CID 8962102.
^Tessema MZ, Koets AP, Rutten VP, Gruys E (November 2001). "How does Mycobacterium avium subsp. paratuberculosis resist intracellular degradation?". The Veterinary Quarterly. 23 (4): 153–62. doi:10.1080/01652176.2001.9695105. PMID 11765232.
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages...
particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called...
phagolysosome, or endolysosome, is a cytoplasmic body formed by the fusion of a phagosome with a lysosome in a process that occurs during phagocytosis. Formation...
around the particle. A phagosome is a cellular compartment in which pathogenic microorganisms can be killed and digested. Phagosomes fuse with lysosomes...
peculiar to mycobacteria, TB bacteria block the fusion of their enclosing phagosome with lysosomes which would destroy the bacteria. Thereby TB can continue...
phagocyte, the bacterium is trapped in a compartment called a phagosome. Within one minute the phagosome merges with either a lysosome or a granule to form a phagolysosome...
been implicated to traffic the endocytosed phagosome to intracellular lysosomes, where fusion of the phagosome and the lysosome produces a phagolysosome...
the phagosome. As the fungus is thermally dimorphic, these microconidia are transformed into yeast. They grow and multiply inside the phagosome. The...
When a macrophage ingests a pathogen, the pathogen becomes trapped in a phagosome, which then fuses with a lysosome. Within the phagolysosome, enzymes and...
macrophages. During normal phagocytosis, bacteria are enclosed by the phagosome, which fuses with the lysosome to become a phagolysosome. The internal...
macrophage and stored temporarily in a membrane-bound vesicle called a phagosome. The phagosome then combines with a lysosome to create a phagolysosome. In the...
the interior of the infected cell by a phagosome.[citation needed] F. tularensis then breaks out of this phagosome into the cytosol and rapidly proliferates...
a phagocyte, it becomes trapped in an intracellular vesicle called a phagosome, which subsequently fuses with another vesicle called a lysosome to form...
phagolysosomal fusion and death, rickettsiae must escape from the phagosome. To escape from the phagosome, the bacteria secrete phospholipase D and hemolysin C....
many microbes, each phagocytic event resulting in the formation of a phagosome into which reactive oxygen species and hydrolytic enzymes are secreted...
yeast-to-hyphal transition within the acidic macrophage phagosome. This initially causes phagosome membrane distension which eventually leads to phagosomal...
and the pathogen and so is kept within a special compartment, called a phagosome. Free hydrogen peroxide will damage any tissue it encounters via oxidative...
the surface of a (target) cell activate phagocytic receptors on a phagocyte, inducing uptake into a phagosome, where the cell is killed and digested....
It can be found in the plasma membrane as well as in the membranes of phagosomes used by neutrophil white blood cells to engulf microorganisms. Human isoforms...
then resides in phagocytic vacuoles, or phagosomes, until it enters the cytoplasm by disrupting the phagosome membrane. Within the cytoplasm, the bacteria...
by preventing maturation of the host-cell phagosome in which the bacterium lives. Maturation of the phagosome would enable it to kill the bacterium. Mutations...
digesting large structures or cellular debris; through cooperation with phagosomes, they are able to conduct autophagy, clearing out damaged structures....
to clear pathogens by oxidative burst, acidification of phagosomes, and fusion of the phagosome and lysosome. B. suis, in return, has developed ways to...
biogenesis, and ATG13 (Autophagy-related protein 13) is required for phagosome formation. Autophagy is executed by ATG genes. Prior to 2003, ten or more...
of inclusion body composed of ferritin aggregates, or mitochondria or phagosomes containing aggregated ferritin. They appear as dense, blue-purple granules...
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