CD8+T细胞和角质形成细胞间的“细胞因子桥梁”在重症大疱型药疹发病机制中的“环路扩大效应”

Severe bullous drug eruption (SBDE) is a lethal dermatological disease. CD8+ T lymphocytes and keratinocytes are considered to play an important role in the pathogenesis. However, the inter-regulation between the two cells is not clear yet. Our previous studies have found that TNF-α and CCL27 in the peripheral blood and the skin lesions of patients with SBDE were increased. TNF-α is secreted by activated CD8+ T cells and can stimulate secreation of CCL27. CCL27 is generated by keratinocytes and is involved in the activation of CD8+ T cells. Therefore, we raise the hypothesis that in the pathogenesis of SBDE, TNF-α secreted by the CD8+ T cells can stimulate keratinopcyte to produce CCL27, whereas, CCL27 promote CD8+ T cells to generate TNF-α. The two cells are linked through the “cytokine bridge”, which cause the “positive loop effect”. In this study, we will isolate CD8+ T cells and primary keratinocytes from the patients with SBDE, and use the techniques including lentivirus packaging, ELISA, Western blot, Real-time PCR, immunofluorescence and cell co-culture system of transwell, in order to study the key link between CD8+ T cells and keratinocytes in SBDE. The results will be beneficial to the pathogenesis and can provide theoretical and experimental basis to the clinical prevention and treatment of the disorder.

重症大疱型药疹是皮肤科的危重疾病。CD8+T细胞和角质形成细胞在其发病机制中均有重要作用，但二者的相互关系尚不完全清楚。前期实验发现TNF-α和CCL27在患者外周血和皮损局部均升高。TNF-α由活化的CD8+T细胞分泌，可促进CCL27的分泌；而CCL27由角质形成细胞产生，并参与CD8+T细胞活化。由此我们提出假说，在重症大疱型药疹中，CD8+T细胞分泌的TNF-α刺激角质形成细胞分泌CCL27，而CCL27促进CD8+T细胞分泌TNF-α。两种细胞通过“细胞因子桥梁”，形成“环路扩大效应”。本研究拟通过分离CD8+T细胞和角质形成细胞，运用慢病毒包装与感染、ELISA、Western blot、Real-time PCR、免疫荧光等技术手段，结合transwell细胞共培养体系，探索CD8+T细胞和角质形成细胞在重症大疱型药疹中的互调作用，为深究疾病的发病机制和临床防治提供依据。

重症大疱型药疹（Stevens-Johnsons syndrome/toxic epidermal necrolysis, SJS/TEN）是皮肤科危重疾病，以CD8+ T细胞介导的免疫反应为基本发病机制，皮肤角质形成细胞凋亡为基本病理生理学基础。CD8+ T细胞相关炎症因子如TNF-α在疾病中可能具有重要作用，但炎症因子之间的联系、与内脏损伤等的关系仍不清楚。本课题首先研究了TNF-α和趋化因子CCL27在SJS/TEN病程不同时间点以及在系统和局部皮肤的表达情况，发现TNF-α具有在整个病程中和皮肤局部异常高表达的特点，而且，TNF-α与其他多种升高的炎症因子如IL-15、IL-12等均有正相关关系，提示TNF-α在SJS/TEN疾病中可能处在炎症反应的上游地位，是免疫炎症过程的使动性因子。同时，我们还发现除了与杀伤有关的炎症因子有上调性表达之外，表皮来源的炎症因子如IL-33等也有高表达。在多年的临床实践中我们发现一组病人表现为肝肾意外的其他少见内脏器官损伤，如间质性肺炎和胰腺炎。我们在对此类患者的炎症因子研究中发现，不同炎症因子可能与不同的内脏器官损伤有关，如IL-6可能和间质性肺炎有关，而IL-18可能成为SJS/TEN合并胰腺损伤的标志性炎症因子。研究结果印证了TNF-α在疾病中的关键地位，也为目前课题组正在开展的抗TNF-α抗体治疗SJS/TEN的超说明书用药打下了坚实的基础，同时，对于其他炎症因在疾病中具体作用的研究和临床表型的关系也为生物靶向药物应用于SJS/TEN提供了启发。