Tao Zhu1, Dan Zhou1, Zhe Zhang1, Lina Long1, Yujuan Liu1, Qinghong Fan1, Feifan Chen1, Xueke Zhang1, Yan Wu2, Hekun Zeng1, Alexei Verkhratsky3, Jianhao Zhao2, Hong Nie4. 1. Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, People's Republic of China. 2. Department of Materials Science and Engineering, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, People's Republic of China. 3. Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom. 4. Guangdong Province Key Laboratory of Pharmacodynamic Constituents of TCM and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou 510632, People's Republic of China; International Cooperative Laboratory of Traditional Chinese Medicine Modernization and Innovative Drug Development of Chinese Ministry of Education (MOE), College of Pharmacy, Jinan University, Guangzhou 510632, People's Republic of China. Electronic address: tnieh@jnu.edu.cn.
Abstract
BACKGROUND: Allergic contact dermatitis (ACD) is a highly prevalent inflammatory and immune skin disease accompanied with persistent pruritus and pain. Oxymatrine (OMT) exhibits antipruritic and anti-inflammatory effects in squaric acid dibutyl ester (SADBE) induced ACD mice model, but the need for frequent administration stipulated by short half-life and low bioavailability limits clinical application. OBJECTIVE: To evaluate the analgesic and antipruritic effects of OMT gel (OG), OMT sustained release microgel powder (OMP) and OMT sustained release microgel cream (OMC) in SADBE induced ACD mice, with subsequent study of the mechanism and side effects (irritation) of optimal dosage form. METHOD: On day 11, the thickness of the right cheek skin of mice was measured and mice spontaneous behaviors were recorded for 1.5 h. In the OMC experiment, hematoxylin-eosin and toluidine blue staining were performed on the cheek skin, and the irritation of OMC was tested on the back skin of rabbits. Blood analyzer was used to measure the counts of inflammatory cells in peripheral blood. The mRNA expressions of IL-1β, TNF-α, CXCR3, CXCL10, IL-6, IL-10, IL-17A and IL-31 in cheek skin, TRPA1 and TRPV1 channels in trigeminal ganglion (TG), IFN-γ in spleen and IL-17A in thymus were measured by RT-qPCR. RESULTS: OMC, OMP and OG significantly decreased wipes and scratching bouts, alleviated skin inflammation. OMC required less frequent administration and is easier to apply, while its antipruritic effect was stronger than the analgesic effect. OMC rescued the deficits in epidermal keratinization and inflammatory cell infiltration, decreased the leukocyte count in peripheral blood, had no irritation to the broken rabbit's skin. Furthermore, OMC significantly down-regulated the mRNA expression of IL-1β, TNF-α, CXCR3, CXCL10, IL-6, IL-10, IL-17A and IL-31 in cheek skin, TRPA1 and TRPV1 channels in TG, IFN-γ in thymus and IL-17A in spleen. CONCLUSION: We have demonstrated that OMC exhibits advanced analgesic, antipruritic and anti-inflammatory effects when compared with OG and OMP in ACD mice by regulating inflammation, chemokines, immune mediators and inhibiting the mRNA expression of TRPA1 and TRPV1. OMC has no irritation to the intact and damaged skin of rabbits.
BACKGROUND:Allergic contact dermatitis (ACD) is a highly prevalent inflammatory and immune skin disease accompanied with persistent pruritus and pain. Oxymatrine (OMT) exhibits antipruritic and anti-inflammatory effects in squaric acid dibutyl ester (SADBE) induced ACDmice model, but the need for frequent administration stipulated by short half-life and low bioavailability limits clinical application. OBJECTIVE: To evaluate the analgesic and antipruritic effects of OMT gel (OG), OMT sustained release microgel powder (OMP) and OMT sustained release microgel cream (OMC) in SADBE induced ACDmice, with subsequent study of the mechanism and side effects (irritation) of optimal dosage form. METHOD: On day 11, the thickness of the right cheek skin of mice was measured and mice spontaneous behaviors were recorded for 1.5 h. In the OMC experiment, hematoxylin-eosin and toluidine blue staining were performed on the cheek skin, and the irritation of OMC was tested on the back skin of rabbits. Blood analyzer was used to measure the counts of inflammatory cells in peripheral blood. The mRNA expressions of IL-1β, TNF-α, CXCR3, CXCL10, IL-6, IL-10, IL-17A and IL-31 in cheek skin, TRPA1 and TRPV1 channels in trigeminal ganglion (TG), IFN-γ in spleen and IL-17A in thymus were measured by RT-qPCR. RESULTS: OMC, OMP and OG significantly decreased wipes and scratching bouts, alleviated skin inflammation. OMC required less frequent administration and is easier to apply, while its antipruritic effect was stronger than the analgesic effect. OMC rescued the deficits in epidermal keratinization and inflammatory cell infiltration, decreased the leukocyte count in peripheral blood, had no irritation to the broken rabbit's skin. Furthermore, OMC significantly down-regulated the mRNA expression of IL-1β, TNF-α, CXCR3, CXCL10, IL-6, IL-10, IL-17A and IL-31 in cheek skin, TRPA1 and TRPV1 channels in TG, IFN-γ in thymus and IL-17A in spleen. CONCLUSION: We have demonstrated that OMC exhibits advanced analgesic, antipruritic and anti-inflammatory effects when compared with OG and OMP in ACDmice by regulating inflammation, chemokines, immune mediators and inhibiting the mRNA expression of TRPA1 and TRPV1. OMC has no irritation to the intact and damaged skin of rabbits.