From the Guidelines
A phagosome is a membrane-bound vesicle formed during phagocytosis, where a phagocytic cell engulfs and destroys foreign particles or microorganisms, playing a crucial role in the innate immune system. The process of phagocytosis involves the extension of the cell membrane to surround the target, forming a phagosome, which then undergoes maturation by fusing with lysosomes to form a phagolysosome 1. Inside the phagolysosome, the engulfed material is broken down by acidic conditions and hydrolytic enzymes. Phagosomes are essential for defending against infections and maintaining tissue homeostasis by clearing unwanted materials from the body.
Some key aspects of phagosomes include:
- Formation: Phagosomes are formed when a phagocytic cell, such as a macrophage or neutrophil, engulfs a foreign particle or microorganism 1.
- Maturation: The newly formed phagosome undergoes maturation by fusing with lysosomes, resulting in the formation of a phagolysosome 1.
- Function: Phagolysosomes break down the engulfed material using acidic conditions and hydrolytic enzymes, allowing the body to eliminate pathogens, dead cells, and debris 1.
- Importance: Phagosomes play a crucial role in the innate immune system, and defects in phagosome formation or function can lead to increased susceptibility to infections and various inflammatory disorders 1.
The study of phagosomes and their role in the autophagic process has been extensively researched, with guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes providing valuable insights into the mechanisms involved 1. Understanding the formation, maturation, and function of phagosomes is essential for appreciating their importance in maintaining cellular homeostasis and defending against infections.
From the Research
Definition and Formation of Phagosome
- Phagocytosis is a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter, including microorganisms, foreign substances, and apoptotic cells 2.
- The process of phagocytosis involves several phases: detection of the particle to be ingested, activation of the internalization process, formation of a specialized vacuole called phagosome, and maturation of the phagosome to transform it into a phagolysosome 2, 3.
- Phagosomes are formed when pathogens are initially engulfed into a plasma membrane-derived vacuole 4.
Maturation and Resolution of Phagosome
- After internalizing microbial pathogens via phagocytosis, phagosomes undergo a series of 'maturation' steps, to form an increasingly acidified compartment and subsequently fuse with the lysosome to develop into phagolysosomes and effectively eliminate the invading pathogens 5.
- The molecular events underlying the stages of phagosome formation, maturation, and resolution are being unraveled 3.
- Phagosome maturation is a complex process that requires exquisite spatial and temporal orchestration 3.
Interaction between Phagosome and Bacteria
- When attempting to propagate infections, bacterial pathogens encounter phagocytes that encase them in vacuoles called phagosomes 6.
- Within phagosomes, bacteria are bombarded with a plethora of stresses that often lead to their demise, but pathogens have evolved numerous strategies to counter those host defenses and facilitate survival 6.
- Phagosome-bacteria interactions are of interest for next-generation antibacterials, and understanding these interactions can be built up through the combination of immunology, microbiology, and engineering 6.