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Gene & Protein in Disease Exosomes connect periodontitis and systemic diseases

which can directly merge with a preexisting ESE. The trans- exosomes also enter serum, lymph and cerebrospinal fluid,
Golgi network (TGN) and endoplasmic reticulum (ER) breast milk, urine, saliva, and other body fluids to play
also can contribute to the formation and contents of ESE. different biological roles [61,62] .
ESEs can mature into late-sorting endosomes (LSEs), they After released by parent cells, exosomes can navigate
can become multivesicular bodies (MVBs) due to the LSEs
accumulation. This process results in MVBs containing through extracellular fluid for varying times and distances.
[55]
several exosomes . MVBs can fuse with autophagosomes, When exosomes reach the location of particular tissue,
and the contents are degraded in the lysosomes ultimately, they are internalized by recipient cells through receptor-
MVBs can also directly fuse with lysosomes for mediated endocytosis, pinocytosis, and phagocytosis, or
degradation. The degradation products could be recycled through the fusion with cell membrane, which results in
[63]
by the cells . Besides, MVBs can be transported to plasma direct release of contents into cytoplasm . The receptor-
[56]
membrane and docked on the luminal side of plasma mediated endocytosis plays a critical role during the
membrane by the help of MVB-docking proteins to release entry of exosomes into target cells. Exosomes can interact
these exosomes [53,57] . Through the above process, cells can with recognized specific target cells and then establish
package cargoes consisting of selective lipids, proteins, interactions with the surface of recipient cells by binding to
and nucleic acids in exosomes, and such cargoes can be their receptors or other appropriate sites, which is followed
transported to recipient cells, contributing to expressional by exosomes fusion with plasma membrane. After this
and functional changes (Figure 2). process, exosomes can discharge the luminal cargoes into
[58]
the recipient cells, resulting in the physiological change
3.2. Uptake of exosomes of recipient cells. After that, exosomes components can
As a kind of extracellular vesicles, exosomes can be released be reassembled in new vesicles that are recycled by other
[16]
from a variety of cells including fibroblasts, intestinal ECs, cells to activate effector networks . Exosomes can also
neurons, and adipocytes [59,60] . Exosomes tend to move release contents into recipient cells by fusing with cells.
through the intercellular junctions, leave their initial fluid Subsequently, exosomes membranes and cargoes can
and move to adjacent areas of tissues, and communicate redistribute in the recipient cell, which can then be recycled
with neighboring cells through cell-cell connections, for MVBs or plasma membrane assembly, respectively.
which is the primary function of exosomes. Meanwhile, Recycled exosomes are released to the extracellular fluid

Figure 2. Biogenesis and uptake of exosomes. Exosomes are originated from the invagination of cell membranes containing special contents, which leads to
the production of ESEs. Instantly, intracellular proteins and nucleic acids merged with ESEs to form LSEs, ER and TGN also can participate in this process.
Eventually, LSEs mature into MVBs, which contain many newly formed exosomes and some of them will be excreted out of the body after being digested
by autophagosomes or lysosomes, while others will be secreted out of donor cell as carriers. Along with the transport of body fluids, these exosomes can
release contents into the recipient cells by fusion or endocytosis, causing physiological changes in the recipient cells. ESEs: Early-sorting endosomes, ER:
Endoplasmic reticulum, TGN: Trans-Golgi network, LSEs: Late-sorting endosomes.

Volume 1 Issue 2 (2022) 4 https://doi.org/10.36922/gpd.v1i2.99