氧化应激活化cIAP-RIPK1-NF-kB信号调控白癜风CD8+T细胞皮肤迁移新机制

In vitiligo, oxidative stress induced-autoimmune response has been attributed to melanocytes (MC) destruction. Nevertheless, the mechanism of vitiligo initiation during oxidative stress is still unclear. We recently found that stressed MC could secret the chemokines CXCL10 and CXCL16, which probably play a critical role in CD8+T cells skin migration for the initiation stage of vitiligo. Latest studies also reveal that cIAP, as a key regulator of RIPK1 polyubquitination, is required for NF-kB-depended cytokines and chemokines production. Our previous data suggested that cIAP expression in MC could be induced by oxidative stress, thus we infer that oxidative stress may activate cIAP-RIPK1-NF-kB signaling pathway, which induce chemokines CXCL10 and CXCL16 production and CD8+T cells skin migration, and consequently lead to the initiation of vitiligo. For further investigation of this program, we will firstly confirm the previous observation in vitiligo clinical samples, and then explore the underlying mechanism of chemokines production under oxidative stress; finally we will illustrate the trafficking function of chemokines CXCL10 and CXCL16 for vitiligo CD8+T cells. Our research will fully elucidate the mechanism of CD8+T cells skin migration in vitiligo initiation, which may help to develop more effective treatments for patients.

氧化应激引起T细胞免疫应答是白癜风黑素细胞（MC）死亡的重要原因，但其起始阶段及调控机制不清楚。我们发现氧化应激诱导MC分泌CXCL10、CXCL16是驱动CD8+T细胞向皮肤迁移的关键早期事件，但机制不清。最新研究表明，凋亡抑制因子cIAP泛素化修饰RIPK1，是NF-kB依赖的细胞因子表达的关键机制。我们发现cIAP在应激的MC中表达升高，预测NF-kB调控CXCL10、CXCL16基因转录，由此提出科学假说：氧化应激活化cIAP-RIPK1-NF-kB信号诱导CXCL10、CXCL16表达，介导CD8+T细胞向皮肤迁移，导致白癜风发生。本项目拟首先在临床样本中确立现象，进一步在原代MC中阐明氧化应激诱导CXCL10、CXCL16表达的机制，最后通过体外趋化实验阐明其介导白癜风CD8+T细胞迁移的功能。预期结果将揭示白癜风CD8+T细胞皮肤迁移机制，为白癜风治疗新策略提供关键靶点。

白癜风是皮肤科常见的色素脱失性疾病，主要为黑素细胞破坏导致白斑形成。以往研究证实，氧化应激可直接作用于黑素细胞介导其死亡，还可启动异常免疫应答导致黑素细胞被免疫细胞靶向杀伤，但具体的机制及关键的启动事件并未完全阐释清楚。本项目我们旨在研究氧化应激下黑素细胞死亡及其触发的免疫事件。我们首先鉴定了白癜风患者皮损周黑素细胞死亡情况，发现白癜风患者黑素细胞表达坏死标志物p-RIPK3及p-MLKL，证实白癜风患者黑素细胞发生程序性坏死；进一步体外研究证实，氧化应激下，黑素细胞中RIPK1表达升高，活化并与RIPK3形成坏死体，进而触发p-MLKL转运至细胞膜，介导黑素细胞发生程序性坏死的具体机制。进一步针对氧化应激诱导免疫细胞趋化机制研究，发现介导CD8+T细胞和CD4+T细胞向皮肤迁移的趋化因子，包括CXCL16、CCL20等，均主要来源于角质形成细胞，而非黑素细胞。本项目着重研究了目前在白癜风发病机制中作用及调控机制均不清楚的CCL20，发现氧化应激激活角质形成细胞中NF-kB信号通路促进CCL20的表达及分泌，并发现白癜风皮损周浸润的CCR6+Th17显著增多，提示CCL20与受体CCR6结合，促进Th17细胞向皮肤组织迁移的机制。本项目首次揭示了氧化应激诱导白癜风黑素细胞程序性坏死的机制，并阐明了氧化应激诱导角质形成细胞中CCL20表达分泌，促进Th17细胞向皮肤迁移，参与黑素细胞免疫损伤的机制，为进一步理解白癜风发病机制、开发新的治疗策略提供了新的理论依据和关键靶点。