Department of Dermatology and Center for Chronic Pruritus, University Hospital Münster, Münster, Germany.
J Eur Acad Dermatol Venereol. 2018 Sep;32(9):1535-1541. doi: 10.1111/jdv.14857. Epub 2018 Mar 9.
Topical capsaicin shows efficacy in the treatment of brachioradial pruritus (BRP); however, its mechanisms of action remain unclear.
The effect of capsaicin on the epidermis (i.e. peripheral expression of non-neuronal sensory receptors on keratinocytes, morphological changes in innervation) is still unknown. We aimed to investigate the effect of topical capsaicin on keratinocyte expression of TRP channels and on the intraepidermal nerve fibre density (IENFD) in patients with BRP.
Thirty-one patients with BRP received an 8% capsaicin patch. Biopsies in lesional and non-lesional skin were taken to assess epidermal morphology, keratinocyte expression of TRP channels and IENFD before and 3 weeks after treatment.
Treatment with the capsaicin patch led to a significant decrease in itch and paresthetic symptoms (P < 0.05). Keratinocyte morphology is unaltered after capsaicin therapy. Reduced keratinocyte expression of TRPV1 in lesional skin (P = 0.009; n = 9) normalized 3 weeks after treatment (P = 0.016; n = 10), but not the IENFD, which remained reduced in lesional epidermis.
The normalization of the decreased TRPV1 expression may account for the effectiveness of topical capsaicin, which does not reconstitute the reduced IENFD, arguing for a role of epidermal TRPV1 in the maintenance of BRP.
局部辣椒素在治疗桡尺部瘙痒症（BRP）方面显示出疗效；然而，其作用机制仍不清楚。
辣椒素对表皮的影响（即角质形成细胞中非神经元感觉受体的外周表达，神经支配的形态变化）尚不清楚。我们旨在研究局部辣椒素对 BRP 患者角质形成细胞 TRP 通道表达和表皮内神经纤维密度（IENFD）的影响。
31 例 BRP 患者接受 8%辣椒素贴片治疗。在治疗前和治疗后 3 周，对皮损和非皮损皮肤进行活检，以评估表皮形态、TRP 通道在角质形成细胞中的表达和 IENFD。
辣椒素贴片治疗可显著减轻瘙痒和感觉异常症状（P < 0.05）。辣椒素治疗后角质形成细胞形态无改变。皮损皮肤中 TRPV1 表达减少（P = 0.009；n = 9），治疗 3 周后恢复正常（P = 0.016；n = 10），但 IENFD 仍减少，皮损表皮中 IENFD 仍减少。
TRPV1 表达减少的正常化可能是局部辣椒素有效治疗的原因，而 IENFD 并未恢复，表明表皮 TRPV1 在维持 BRP 中起作用。
