阻止凋亡细胞继发性焦亡在SLE发病及治疗中的意义

Increased apoptosis and defect in clearance that result in massive secondary necrosis of apoptotic cells have been recognized as the main cause of systemic lupus erythematosus (SLE). Although secondary necrosis has been considered as passive and irreversible form of cell death, recent findings revealed that secondary necrosis after apoptosis is an active, programmatic and controllable way of cell death that is mediated by the activation of caspase 3, the cleavage GSDME and pore formation of plasma membrane. In this project, we call the secondary necrosis after apoptosis as secondary pyroptosis. We believe that blocking secondary pyroptosis will maintain the cells in the apoptosis stage for longer time, thereby promoting the induction of immune tolerance, which may be an effective strategy for the treatment of SLE. Evidence has indicated that a JNK inhibitor reduced GSDME-mediated pyroptosis, suggesting that JNK may be a key molecule that modulates the activity of GSDME. Thus, we aim to investigate the roles of GSDME and JNK in secondary pyroptosis of apoptotic cells and to evaluate the significance of secondary pyroptosis on SLE pathogenesis. In addition, for further understanding the mechanisms of secondary pyroptosis in SLE pathogenesis and development, we will identify the effects of inhibiting secondary pyroptosis on immune balance and on pristane-induced lupus mice. We believe that study will provide novel strategy and potential therapeutic approach for SLE treatment.

机体凋亡细胞增多、清除受限，导致继发性坏死是系统性红斑狼疮（SLE）重要发病机制之一。既往认为继发性坏死是被动的、不可调控的细胞死亡方式，但最新报道表明凋亡继发性坏死是由caspase3活化、剪切GSDME、细胞膜打孔, 导致的一种细胞焦亡，是主动、程序化和可调控的病理生理过程，本标书中我们称之为“继发性焦亡”。我们认为，通过阻止凋亡细胞继发性焦亡，使细胞长时间停留在凋亡阶段，从而促进免疫耐受诱导，可能成为治疗SLE等自身免疫性疾病的有效手段。JNK抑制剂能减少GSDME导致的细胞死亡，提示JNK可能是调控GSDME的关键靶点。本课题组拟对GSDME、JNK调控凋亡继发性焦亡机制进行研究，评估凋亡继发性焦亡在SLE发病中意义，明确抑制凋亡继发性焦亡对免疫平衡影响及在狼疮小鼠模型中作用，从而阐明凋亡继发性焦亡在SLE发病及进展中作用及机制，为SLE治疗提供新思路、新靶点。

系统性红斑狼疮（SLE）是一类主要累及女性，以多器官功能损害为特征的自身免疫疾病，其发病率高、病情复杂，目前发病机制尚不完全清楚。机体凋亡细胞增多、清除受限，导致继发性坏死是SLE发病的重要机制之一。最新研究表明凋亡细胞继发性坏死可能是由GSDME介导的一种细胞焦亡，本研究中我们称之为“凋亡继发性焦亡”。既往研究发现，JNK抑制剂（SP600125）能减少GSDME介导的细胞死亡，提示JNK可能是调控GSDME的关键靶点，但其机制尚不明确。.本研究拟对JNK抑制剂（SP600125）调控GSDME介导的凋亡继发性焦亡相关机制进行研究，明确抑制凋亡继发性焦亡对免疫平衡影响及在狼疮小鼠模型中作用，为SLE治疗提供新思路、新靶点。本研究体外实验以人肾小管上皮细胞系（HK2细胞）为研究对象，探讨SP600125对肾小管上皮细胞继发性焦亡的影响。体内动物实验主要应用pristane诱导狼疮小鼠及MRL/lpr狼疮小鼠模型，观察SP600125治疗后，对狼疮小鼠病情的影响，明确SP600125能否通过抑制GSDME蛋白的表达，阻止凋亡继发性焦亡，在狼疮模型小鼠中发挥治疗作用。.本研究发现：狼疮患者肾脏标本及狼疮小鼠肾脏肾小管中高表达GSDME。凋亡诱导剂TNF+CHX可诱导肾小管上皮细胞继发性焦亡；SP600125可通过抑制caspase3活化及GSDME蛋白表达，抑制肾小管上皮细胞焦亡。狼疮患者血清可促进细胞GSDME蛋白表达，诱导肾小管上皮细胞发生继发性焦亡，SP600125可抑制狼疮患者血清诱导的细胞凋亡继发性焦亡。体内实验发现SP600125可改善Pristane诱导狼疮小鼠及MRL/lpr狼疮小鼠病情，表现为狼疮小鼠的尿蛋白降低、肾脏病理损害减轻、炎症因子分泌减少以及Th1/Th2细胞比值降低。Pristane诱导狼疮小鼠及MRL/lpr狼疮小鼠肾小管均高表达GSDME及Cleaved-caspase3，SP600125治疗可减少狼疮小鼠肾小管caspase3活化及GSDME表达，提示SP600125可通过抑制GSDME介导的凋亡继发性焦亡从而在狼疮模型小鼠中发挥治疗作用。.综上，GSDME介导的凋亡继发性焦亡增多可能是SLE发病机制之一，SP600125可通过抑制caspase3活化及GSDME表达，调控凋亡细胞继发性焦亡，从而成为治疗系统性红斑狼疮的潜在靶点。