微环境调控Tim-3表达进而影响免疫细胞稳态的机制及意义研究

Recently scientists pay high attention to the relationship between damaged immune homeostasis and the onset of many immune-related clinical diseases. Our previous data and recent literature showed that Tim-3, an immune regulator, is downregulated in autoimmune conditions such as sepsis, inflammatory bowel disease, while upregulated in immunosuppressive diseases such as colon cancer, and the dysregulated Tim-3 expressions are closely related to the damaged immune homeostasis and diseases onset respectively. However, factors manipulating Tim-3 expression in different microenvironments and mechanisms by which Tim-3 signaling mediates immune homeostasis remain largely unclear. To test the feasibility of using Tim-3 as therapeutic target for treating immune-related diseases, the proposal here will focus on the following projects:①Determining the factors manipulating Tim-3 expression in different microenvironments and making clear the underlying mechanisms.② Making clear the mechanisms especially the signaling cascades by which Tim-3 mediates immune cell homeostasis. ③ Investigating the mechanisms by which Tim-3 interventions reversed immune homeostasis and attenuated diseases progression of autoimmune diseases (sepsis) and of immunosuppressive diseases (colon cancer), making clear whether Tim-3 can be used as a therapeutic target for above immune related diseases.

免疫细胞稳态的异常与多种免疫相关性疾病发生发展的关系近来倍受人们关注。我们前期的研究及相关文献证实：免疫调控分子Tim-3在免疫损伤性疾病如脓毒症的低表达，或在免疫抑制性疾病如肠肿瘤的高表达是导致免疫细胞稳态异常及疾病发生发展的重要因素。微环境影响Tim-3表达进而影响免疫细胞稳态及疾病转归的机制及意义尚不清楚。为深入认识Tim-3在免疫稳态调控中的作用及分子机制，寻求新的疾病干预靶点，本项目拟在前期研究基础上以巨噬细胞为切入点，重点探讨：1）不同微环境调控Tim-3在免疫细胞上不同表达的分子机制；2）Tim-3异常表达影响免疫细胞稳态的细胞内信号传导机制； 3）干预Tim-3通路对免疫损伤性疾病（脓毒症）、免疫抑制性疾病（肠肿瘤）体内免疫细胞稳态的影响及机制，明确将Tim-3作为上述疾病干预靶点的可行性。

Tim-3是一广泛表达于T细胞及天然免疫细胞上的免疫检查点分子，因其高表达导致免疫细胞的功能耗竭及感染、肿瘤的免疫逃逸，而被认为是继CTLA-4、PD-1之后的新一代免疫治疗靶点。本项目旨在阐明Tim-3调控巨噬细胞稳态的分子机制。主要围绕Tim-3表达变化、巨噬细胞稳态异常、疾病进程三者之间的关系展开研究。1）发现在naïve状态下促炎性介质及抗炎性介质均可上调巨噬细胞上Tim-3的表达，而在Tim-3高表达的状态下，只有促炎性介质如LPS可以下调Tim-3的表达，而抗炎性介质如TGF-b持续诱导Tim-3 mRNA的表达，提示不同微环境可通过调控Tim-3的表达而影响免疫细胞的稳态。金属蛋白酶ADAM10或ADAM17 参与了炎症介质对Tim-3膜表达的调控过程。2）初步阐明了Tim-3调控巨噬细胞极化，参与肠炎及肠肿瘤发生、发展的分子机制。发现Tim-3可以通过结合STAT1这一接头蛋白，抑制STAT1磷酸化及核转位，最终抑制miR-155及SOCS1通路介导的巨噬细胞极化过程。同时还发现Tim-3通过促进NRF-2的泛素化抑制巨噬细胞的吞噬功能，通过抑制NLRP3的表达及活化等机制抑制巨噬细胞介导的炎性小体的分泌。3）最后我们还制备了抗人Tim-3的抗体，Tim-3融合蛋白等免疫制剂，为免疫相关疾病的干预提供了理论及实验依据。.受本项目资助， 截至目前我们发表标有本课题号的SCI研究论文15篇， 获得与本课题有关的国家发明专利授权3项，获得美国发明专利授权1项，培养博士研究生3名，硕士研究生6名，完成了预定的目标任务。