Bigelovin通过调控TSLP基因长型转录变异体治疗特应性皮炎的作用研究

Atopic dermatitis(AD) is a common, chronic, relapsed, pruritus disease. It always occurs in childhood, affecting quality of life obviously. Most of the patients need steroids for treatment. Thymic stromal lymphopoietin (TSLP) has proved to be a key role in pathogenesis of AD. Human TSLP gene has 2 transcript variants called long form and short form. In the previous study, we reported that keratinocytes expressed TSLP protein in AD and mainly expressed long form TSLP gene, which correlated to level of TSLP protein as well. But the normal keratinocytes mainly express short form TSLP gene and secrete little TSLP protein. Recently, we found that the novel medicine for AD, 9-cis retinoic acid, which is a retinoid X receptor(RXR) agonist, could significantly downregulate long form TSLP and TSLP protein induced by TLR ligands in human keratinocytes, similar to Dexamethasone. However, retinoids may increase the risk of premature epiphyseal closure and should be avoided to use in children and teenagers. Therefore, if there are other natural RXR agonists also decrease TSLP gene and protein in skin acting like 9-cis retinoic acid, they could be explored for treating AD children. Bigelovin is a sesquiterpene lactone isolated from the flowers of Inula, the Chinese traditional herbal medicine which has been constantly used to treat allergic asthma since ancient times. Recent studies revealed that, Bigelovin is a natural RXR agonist, and the thermodynamic property of bigelovin binding to RXR showed an identical binding profile to that of RXRα natural ligand 9-cis retinoic acid, implying a similar mechanism of RXR binding for these two ligands. Therefore, our study attempts to compare the effect of Bigelovin and 9-cis retinoic acid on TSLP gene transcript variants and TSLP protein release in AD both in vitro. and in vivo. It may provide some new information in AD treatment, especially for children.

特应性皮炎(AD)是一种常见的慢性、复发性、瘙痒性皮肤病，常幼年发病，严重影响生活，大多数人需要激素治疗。TSLP是启动其Th2型炎症反应的关键因子。人TSLP基因有长型、短型2种转录变异体。既往研究中我们发现AD表皮主要表达长型TSLP，并与胞外TSLP蛋白相关；而正常表皮则主要表达短型。我们还发现治疗AD的新型药物9-顺式维A酸，一种RXR激动剂，显著降低长型TSLP及TSLP蛋白的水平，效果与地塞米松相当。但维A酸能影响骨骺发育，限制了儿童的使用。因此我们希望找到既能用于儿童、又与9-顺式维A酸作用相似的药物。Bigelovin是治疗哮喘的中药旋覆花的倍半萜类提取物，研究表明它是RXR天然激动剂，并且与RXR结合的位点、方式都和9-顺式维A酸很相似。故本课题通过比较两者对AD表皮细胞长型TSLP和TSLP蛋白表达的影响、以及在小鼠AD模型中的作用，为AD患儿的替代激素治疗提供新思路。

特应性皮炎(AD)是一种常见的慢性、复发性、瘙痒性皮肤病，常幼年发病，严重影响生活，大多数人需要激素治疗。TSLP是启动其Th2型炎症反应的关键因子。人TSLP基因能产生长型、短型2种转录变异体。AD表皮细胞主要表达长型TSLP，并与胞外TSLP蛋白相关，而正常表皮则主要表达短型。核受体激动剂9-顺式维A酸显著降低长型TSLP及TSLP蛋白的水平，效果与地塞米松相当，但对于趋化致病微生物的细胞因子IL-8却没有抑制作用，优于糖皮质激素。但该药引起骨骺提早闭合，儿童慎用。细胞实验中我们发现与该药作用相似的核受体激动剂BMS961和ATRA也有相似效应，可能存在相同作用位点。. 小鼠AD模型的诱导剂MC903也是一种核受体激动剂，其作用于人角质形成细胞系可诱导类似内源性TSLP转录（诱导以短型TSLPmRNA为主，而且并不刺激细胞分泌TSLP蛋白）。但是在外源性配体环境下，MC903可加重长形TSLPmRNA和总TSLPmRNA的表达。MC903外涂小鼠耳部成功诱导AD模型，组织TSLP表达升高、血清IgE水平升高。除了Th2相关的细胞因子TSLP、IL-4升高外，Th1相关的细胞因子Th17、IL-22也有升高。腹腔注射9-cis-RA可以缓解急性期和慢性期的皮肤炎症反应。而特应性皮炎相关致病微生物球形马拉色菌可以加重小鼠炎症反应，感染组TSLP、IL-4表达下降，Th17、IL-22升高，提示马拉色菌加重AD炎症反应可能并非通过抑制Th2相关通路和TSLP途径。另外，具有免疫调节作用的IFN-γ在模型组明显升高，感染组明显降低。. 9-cis-RA临床常用于调节上皮细胞分化和抗肿瘤治疗，我们根据细胞实验结果，设想9-cis-RA抗皮肤癌作用机理。研究中意外发现TSLP与皮肤鳞状细胞癌分化相关。肿瘤分化越低，TSLP表达越高，提示9-cis-RA可能有利于皮肤鳞状细胞癌的防护，其机制可能与抑制TSLP表达有关。