Epidermal Langerhans Cells Act as Neuroimmune Regulators of Pain and Itch

Epidermal Langerhans cells amplify cutaneous sensory signaling, increasing thermal, mechanical, and pruritic responses, and LC activation potentiates chloroquine-evoked scratching via semaphorin 7A.

• Why it matters: Neuroimmune crosstalk in skin is known to coordinate defense and sensation, but how epidermal immune cells tune sensory circuits for pain and itch is unclear.
• What they did: Using anatomical and transcriptomic analyses, the study linked LCs to non-peptidergic sensory neurons, then tested LC activation versus inhibition/ablation and identified semaphorin 7A; neutralizing semaphorin 7A and blocking PlexinC1 were used to test mechanism.
• The result: LC activation increased neuronal and behavioral responses to thermal, mechanical, and pruritic stimuli, while LC inhibition or ablation selectively reduced pruritogen-evoked itch; semaphorin 7A sensitized neurons to chloroquine and histamine, and neutralizing semaphorin 7A or blocking PlexinC1 reduced LC-driven itch potentiation.

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