Extracellular vesicles play an active role in the immune system of lymph nodes

Copyright © iCell Bioscience Inc, Shanghai 2018-2019

Exosomes and microvesicles circulate in all biological fluids and can trigger biological reactions in distal tissues. Their role includes a variety of biological processes, such as immune surveillance, modification of the tumor microenvironment, or regulation of inflammation. Exosomes can carry a large number of active molecules, including lipid mediators that regulate cell phenotypes such as eicosanoids, proteins, and nucleic acids.

Exosomes carry lipid molecules or their lipid-associated enzymes and participate in several pathophysiological processes including inflammation, tumor progression, and atherosclerosis. Extracellular vesicles also play a positive role in the lymph node's immune system, or play a positive role in brain physiology through neuronal activation.

Recent studies have begun parallel studies of the two types of exosomes and vesicles, and it has been demonstrated that both can be produced by the same cells, suggesting possible regulation of biogenesis. In addition, the functions of exosomes and microvesicles appear to be complementary or opposite.

Exosomes play an active role in the immune response by prolonging the duration of antigen presentation in lymph nodes and are expected as an immunotherapy tool against cancer; microbubbles inhibit the conversion of immune response cells into Tregs by inducing CD4 T cell differentiation.

Dendritic cell (DC)-derived exosomes that induce antigen-specific immune responses in vitro are more effective than DC-derived microvesicles. Similar to agonist and antagonist molecules that interact with receptors, further studies on extracellular vesicles have shown that there are also activating vesicles and antagonizing vesicles in the regulation of some physiological processes.

Another major research interest in extracellular vesicles is the detection of biomarkers carried by circulating exosomes or microvesicles in the blood. For example, studies have identified exocrine markers of pancreatic cancer and isolated exosomes carrying PGE2. Or carrying 12-HETE microbubbles will increase diagnostic efficiency. At the same time, "nanodevices" capable of monitoring extracellular vesicles have begun to emerge, such as continuous microfluidic chips.

In conclusion, cell-cell communication mediated by exosomes and vesicles opens up a new era in the study of pathophysiological processes and also provides a potential target for the development of new disease therapies.