Distinct Role of Specialized Cutaneous Schwann Cell Network in Acute and Chronic Pain Sensation.

Specialized cutaneous Schwann cells (scSCs) are a recently identified glial class implicated in cutaneous pain modulation, yet their three-dimensional architecture and role in chronic pain remain unclear. Using tissue optical clearing, we reconstructed the 3D morphology of scSCs, revealing an intricate mesh-like network, with extensive branching penetrating the epidermal layer and establishing close associations with A- and C-fiber primary sensory nerve terminals. Optogenetic activation of scSCs elicited nociceptive reflex behaviors, dependent on concurrent A- and C-fiber activation, but not affective-motivational responses. We further investigated the morphological and functional alterations of scSCs in chronic inflammatory pain and neuropathic pain models. Interestingly, scSCs were found to play a partial role in modulating nociceptive behaviors but not aversions in chronic pain. Together, these findings provide new insights into the functional dynamics of scSCs in nociceptive signal processing and their limited contribution to chronic pain states.