Chronic pain is a significant global health burden. Current treatments, such as opioids, anticonvulsants, and antidepressants, primarily act on the central nervous system (CNS) and often lead to serious side effects, including addiction. This highlights the need for alternative analgesic strategies targeting the peripheral nervous system. The dorsal root ganglia (DRG), containing the somata of primary sensory neurons, represent a promising site for peripheral modulation. These neurons are closely associated with satellite glial cells (SGCs), which support neuronal function and homeostasis. We investigated whether exosome-mediated communication contributes to neuron-glia interactions and sensory neuron excitability. Electron microscopy and immunohistochemistry of rat DRG sections revealed abundant presence of exosome-like vesicles. Western blotting and nanoparticle tracking analysis confirmed exosome release from DRG neurons and purified SGC cultures. Exosomal protein markers, such as CD63 and TSG101, were detected across all exosome samples. Proteomic profiling via LC-MS identified cell-type-specific cargo, including proteins involved in pain signaling. To monitor exosome release, we transfected SGCs with CD63-pHluorin and used total internal reflection fluorescence (TIRF) microscopy to visualize their localization within multivesicular bodies. Immunocytochemistry further confirmed that CD63-pHluorin-positive exosomes derived from SGCs selectively targeted and were internalized by sensory neurons in culture. Calcium imaging of cultured DRG neurons revealed diminished ATP-induced sensory neuron activation after 24-hour incubation with SGC-derived exosomes. Electrophysiological recordings confirmed decreased action potential firing and overall reduced excitability of DRG neurons following SGC-derived exosome treatment. Functionally, intra-DRG injection of SGC-derived exosomes in a decerebrate, arterially perfused preparation (DAPP) of the rat increased DRG filtering of spikes induced by noxious stimulation of the front paw. These findings support a novel, antinociceptive role for SGC-derived exosomes in peripheral sensory modulation, highlighting their therapeutic potential in chronic pain management.
Vincenzo Prato (Sun,) studied this question.