Papers of the Week

Allergic contact dermatitis is a skin inflammatory disease manifested with itch and pain symptom around the inflamed area. Chemokines such as CXCL12 are involved in the pathophysiology of allergic contact dermatitis, but little has been known about the effect of CXCL12/CXCR4 signaling for nociceptive sensation accompanying allergic contact dermatitis. Our study showed that CXCL12 and CXCR4 were upregulated in trigeminal ganglion with the progression of allergic contact dermatitis through western blotting and immunofluorescence. CXCL12 and CXCR4 were mainly upregulated in small-diameter neurons, which were co-localized with nociceptive markers in trigeminal ganglion. CXCR4 and CXCL12 were also expressed in trigeminal ganglion neurons retrograded from the skin lesion. Intradermal injection of CXCL12 enhanced the itch- and pain-like behavior which could be relieved by AMD3100, a CXCR4 antagonist, without changes of mast cells. Our findings suggested that blockade of CXCL12/CXCR4 signaling pathway might be beneficial to relieve itch and pain sensation accompanying allergic contact dermatitis.