Extracellular vesicles derived from ODN-stimulated macrophages transfer and activate Cdc42 in recipient cells and thereby increase cellular permissiveness to EV uptake

Abstract

Endosomal Toll-like receptors (TLRs) mediate intracellular innate immunity via the recognition of DNA and RNA sequences. Recent work has reported a role for extracellular vesicles (EVs), known to transfer various nucleic acids, in uptake of TLR-activating molecules, raising speculation about possible roles of EVs in innate immune surveillance. Whether EV-mediated uptake is a general mechanism, however, was unresolved; and the molecular machinery that might be involved was unknown. We show that, when macrophages are stimulated with the TLR9 agonist CpG oligodeoxynucleotides (ODN), the secreted EVs transport ODN into naïve macrophages and induce the release of chemokine TNF-α. In addition, these EVs transfer Cdc42 into recipient cells, resulting in further enhancement of their cellular uptake. Transport of ODN and Cdc42 from TLR9-activated macrophages to naïve cells via EVs exerts synergetic effects in propagation of the intracellular immune response, suggesting a general mechanism of EV-mediated uptake of pathogen-associated molecular patterns.

The function and clinical application of extracellular vesicles in innate immune regulation

“…159 Microvesicles released from infected red blood cells activate host monocytes and neutrophils. 161 In line with this finding, TLR9-activated macrophages transport ODN to naïve macrophages via EVs, thus inducing the release of chemokine TNF-α, resulting in a synergetic effect in the propagation of the intracellular immune response in vitro 162 (Fig. 2c).…”

“…In addition to ODN, Cdc42 is transferred from EVs into naïve macrophages and further activated by TNF-α, leading to the enhancement of EV uptake. 162 Similar to TLR9, TLR7 and TLR8 localize to intracellular compartments such as endosomes, lysosomes and the ER. 150,152,163 Exosomal miR-21 and miR-29a secreted by lung cancer cells in BALB/c mice were transferred to macrophages where they could bind to TLR7/8, leading to TLR-mediated NF-κB activation and secretion of the prometastatic inflammatory cytokine TNF-α in vitro and in vivo 164 (Fig.…”

Mesenchymal stem cells secretome: The cornerstone of cell-free regenerative medicine

“…As an example of these mechanisms, EVs secreted by activated macrophages are recognized by TLR9 on the surface of inactive macrophages, triggering the release of chemokine TNF-α. In addition, these EVs transfer cell division control protein 42 homolog (Cdc42) into recipient cells triggering the release of more EVs[ 87 ]. A direct interaction between cell surface molecules and the EVs is needed for EVs uptake.…”

Coupling Nanostructured Microchips with Covalent Chemistry Enables Purification of Sarcoma‐Derived Extracellular Vesicles for Downstream Functional Studies

“…[5,6] Such interchanges can result in exchanges of genetic information and functional molecules, [7] leading to the subsequent reprogramming of the recipient cells. [8][9][10] Tumorderived EVs are regarded as "bio logical shuttles" [11] capable of transporting biomolecules to mediate intercellular communication, microenvironment mod ulation, and cancer metastasis. Therefore, in addition to exploring the diagnostic value of tumorderived EVs, [12][13][14] there is growing interest in performing functional studies of tumorderived EVs in cel lular communication, [15,16] (e.g., EV uptake and cargo transfer).…”