  The innate immune system is vital to rapidly responding to pathogens and
Toll-like receptors (TLRs) are a critical component of this response.
Nanovesicular exosomes play a role in immunity, but to date their exact
contribution to the dissemination of the TLR response is unknown. Here we show
that exosomes from TLR stimulated cells (TLR-exosomes) can largely recapitulate
TLR activation in distal cells in vitro. We can abrogate the
action-at-a-distance signaling of exosomes by UV irradiation, demonstrating
that RNA is crucial for their effector function. We are the first to show that
exosomes derived from poly(I:C) stimulated cells induce in vivo macrophage
M1-like polarization within murine lymph nodes. These TLR-exosomes demonstrate
enhanced trafficking to the node and preferentially recruit neutrophils as
compared to control-exosomes. This work definitively establishes the
differential effector function for TLR-exosomes in communicating the activation
state of the cell of origin.
