Down-regulated expression of transient receptor potential ankyrin 1 in lichen simplex chronicus

Lichen simplex chronicus (LSC) is an acquired chronic dermatosis that is often accompanied by severe paroxysmal pruritus, and its pathogenesis to date is still unclear. Transient receptor potential channel A1 (TRPA1) is a non-selective cation channel. TRPA1 is widely expressed in skin, sensory neurons, and various other tissues, along with various biological functions and activation mechanisms. This study aimed to explore the changes in TRPA1 expression in human LSC and provide evidence for further research on the role of TRPA1 in chronic pruritus.

A total of 21 skin lesion specimens from LSC patients with skin pruritus lasting more than 6 weeks, and 28 normal skin tissue specimens through the skin biopsy from June 2018 to February 2019 were collected. The expression of TRPA1 in these skin tissues was evaluated through western blotting, quantitative reverse transcription PCR (qRT-PCR), and immunohistochemical analysis. The changes of inflammatory mediators, including interleukin (IL)-6, IL-13, endothelin-1 (ET-1), and thymic stromal lymphopoietin (TSLP), as well as substance P, are also analyzed by qRT-PCR. TRPA1 was detected using immunohistochemistry for all skin layers, the basal layer, and around the blood vessels of the dermis.

The expression of TRPA1 in LSC specimens was significantly decreased as compared with that in the normal specimens (P<0.05). Also, TRPA1 protein levels were consistently decreased in LSC specimens (P<0.05). Simultaneously, the mRNA expressions of TRPA1, IL-6, IL-13, ET-1, TSLP, and substance P presented with no significant differences between LSC and normal specimens.

TRPA1 expression is proved downregulated in skin lesions of LSC patients with skin pruritus, indicating that TRPA1 serves as a crucial role in the pathogenesis of human LSC.