Squaric acid dibutyl ester(Squarex)

The seeds of Entada phaseoloides (Linn.) Merr. commonly named "Ke-teng-zi" is a traditional Chinese folk medicine and reported to treat dermatitis, spasm, and headache. However, the exact effect and the mechanism of Ke-teng-zi on the treatment of dermatitis is unclear.

To elucidate the antipruritic effect and molecular mechanisms of Ke-teng-zi on the treatment of allergic contact dermatitis (ACD).

The main components of the n-butanol fraction of 70% ethanol extract from Ke-teng-zi (abbreviated as KB) were analyzed by HPLC. The chloroquine (CQ)-induced acute itch and squaraine dibutyl ester (SADBE)-induced ACD chronic itch in mice was established, and the TNF-α/IFN-γ stimulated Human keratinocytes (HaCaT) were used to evaluate the antipruritic and anti-inflammatory effects of KB. Behavioral tests, lesion scoring, and histology were also examined. The expression levels of molecules in MAPK and JAK/STAT3 pathways, the mRNA levels of chemokines and cytokines in both the skin of ACD mice and the HaCaT cells were detected by western blot and qPCR. Furthermore, whole-cell patch-clamp recordings in TRPA1-tranfected HEK293T cells were used to elucidate the effect of KB on TRPA1 channels. TRPA1 siRNA was used to evaluate the role of TRPA1 in the anti-inflammatory effect of KB in keratinocytes.

The main compounds in KB could bind to the active sites of TRPA1 mainly through hydrogen bond and hydrophobic bond interactions. KB could inhibit the scratching behavior in CQ-induced acute itch, and the inhibitory effect of KB was blocked by TRPA1 inhibitor HC-030031. In addition, KB significantly decreased the scratching bouts of ACD mice, reduced the skin lesion scores, mast cells degranulation, and epidermal thickening, inhibited the production of inflammatory chemokines/cytokines and CGRP, and down-regulated the levels of p-ERK1/2, p-p38, and p-STAT3, compared to the ACD mice. Moreover, continuous application of KB induced the desensitization of TRPA1 channels. Also, KB inhibited the expression of p-ERK1/2, p-p38, and p-STAT3, and down-regulated the expression of inflammatory chemokines and cytokines in vitro, which were reversed by the TRPA1 siRNA.

KB alleviated the pruritus and skin inflammation in ACD mice through TRPA1 channels desensitization and down-regulation of intracellular MAPK and JAK/STAT3 signaling pathways. Our results suggested that Ke-teng-zi is a potential drug for the treatment of inflammatory skin diseases such as ACD.

Alopecia areata (AA) is a non-scarring hair loss disorder. Alopecia totalis (AT) and alopecia universalis (AU) are the severe subtypes of AA. Age of onset before 6 years of age, disease duration of more than 1 year, and extensive alopecia involving more than 50% of the scalp (including AT or AU) suggest a poorer prognosis. Topical corticosteroids are the preferred first-line treatment for pediatric AA. While some treatments, such as intralesional corticosteroids, systemic steroids, contact immunotherapy with squaric acid dibutyl ester, and JAK inhibitors, showed efficacy in adults with AA, their safety profiles limit their use in pediatric AA patients. Dupilumab is a biologic that effectively addresses the patho-physiology of Th2 allergic diseases, and treats atopic diseases by inhibiting the helper Th2 immune axis. AA has been reported to be significantly improved with dupilumab for atopic dermatitis (AD) in children and adults. We report hair regrowth over all of the scalp, eyebrows, and eyelashes after 10 months of dupilumab therapy in a 4-year-old AU patient resistant to baricitinib.