窄谱中波紫外线对瘙痒的作用及机制研究

Effect and mechanism of narrow-band ultraviolet B on pruritus in mice with allergic contact dermatitis

关键词:  窄谱中波紫外线  变应性接触性皮炎  瘙痒

Key words:  narrow-band ultraviolet B  allergic contact dermatitis  itch

摘要:

目的观察窄谱中波紫外线(narrow-band ultraviolet B, NB-UVB)对于2,4-二硝基氟苯(DNFB)诱发的变应性接触性皮炎(allergic contact dermatitis， ACD)小鼠模型瘙痒行为的作用,并初步探讨NB-UVB缓解瘙痒的潜在机制。方法分别用70、84、96 mJ/cm能量的NB-UVB照射C57BL/6小鼠颈背部皮肤，24 h后观察照射部位皮肤的大体及病理改变以确定最小红斑量（minimal erythema dose, MED）。分别在第1、4、8、11天，将0.15% DNFB溶液涂抹于C57BL/6小鼠颈背部皮肤上以建立慢性瘙痒小鼠型，并观察涂药结束后3周内小鼠颈背部皮肤及瘙痒行为改变。在ACD小鼠模型造模成功后，分别用0、56、70 mJ/cm2能量NB-UVB照射模型组小鼠颈背部的皮肤，观察照射部位皮肤的改变并记录小鼠瘙痒行为的变化。采用ELISA、qPCR的方法检照射后小鼠皮肤IL-10及组氨酸脱羧酶(histidine decarboxylase, HDC)的改变。结果正常8~12周龄C57BL/6小鼠颈背部皮肤的MED约为84 mJ/cm2。ACD小鼠模型造模后的第1天，可以观察到局部皮肤渗出、红斑、脱屑、干燥、结痂等改变，且瘙痒行明显增加（P＜0.05），且可持续至造模后的第21天。与对照组及56 mJ/cm2 NB-UVB照射组相比，70 mJ/cm2的NB-UVB可明显改善ACD小鼠颈背部皮肤，且瘙痒行为显著下降（P＜0.05）。ELISA结果提示，照射组小鼠皮肤中IL-10的水平明显升（P＜0.01）。qPCR结果提示，照射组小鼠皮肤中组氨酸脱羧酶水平明显下降（P＜0.05）。结论NB-UVB可通过下调ACD小鼠皮肤中组胺的含量，上调ACD小鼠皮肤中IL-10的含量缓解ACD小鼠的慢性瘙痒行为。

Abstract:

ObjectiveTo investigate the effect of narrow-band ultraviolet B（NB-UVB) on pruritus in mouse and to explore its mechanism. MethodsThe skin of C57BL/6 mice was irradiated by NB-UVB with energy of 70, 84, 96 mJ/cm2 and gross appearance and pathological changes of the skin at the irradiation site were observed to determine the minimal erythema dose（MED). The 2, 4-dinitrofluorobenzene（DNFB) solution（0.15%) was applied on the dorsal neck skin of male C57BL/6 mice to induce the allergic contact dermatitis（ACD) model. The DNFB-treated sites of mice were irradiated with NB-UVB of 0, 56, and 70 mJ/cm2 respectively; and the pathologic changes of the skin and scratching behavior of the ACD mice were compared before and after NB-UVB irradiation. The content of interleukin-10（IL-10) and the expression of histidine decarboxylase（HDC) mRNA in the skin were detected with ELISA and qPCR, respectively. ResultsThe MED on the dorsal neck skin of C57BL/6 mouse was 84 mJ/cm2. In ACD mice the exudation, erythema, desquamation, dryness, crusting and other changes in affected skin were observed; and scratching behavior was increased（P＜0.05）, which lasted at least for 21 d. Compared with the control group, and the skin lesions of ACD mice were significantly improved in NB-UVB irradiation groups, and the scratching behavior was significantly reduced（P＜0.05）. The level of IL-10 was increased（P＜0.01） and the expression of HDC mRNA was decreased significantly in the skin of the irradiated mice（P＜0.05）. ConclusionNB-UVB may alleviate the chronic itch by down-regulating the histamine and up-regulating IL-10 in the skin in ACD mice.