活化性免疫突触在NK细胞微重力响应中的作用及机制研究

The decrease of the killing activity of NK cells by space microgravity results in the decline of immune function, which is one of the most important problems need to be solved in manned space exploration. As the necessary structure of NK cells to achieve its function, activating immunological synapse (aIS) is also the structure product of cytoskeleton (important component in response to the mechanical stimulation) aggregation and rearrangement. And therefore, aIS maybe the key point to reveal the mechanism of NK cells in response to the microgravity. In the normal gravity environment, aIS was positively regulated by NKp46 (p46), and the applicant recently lately found that the expression of p46 was significantly lowered when under the simulated microgravity environment. Therefore, it was possibly that through the mechanical response of p46 to microgravity, the formation of aIS was inhibited and then the NK cell function was suppressed. We plan to①simulate the microgravity environment, study the effect of microgravity on the NK cell function and aIS related mechanical and biological characteristics, which is to illustrate the function of aIS in the response of NK cells to the microgravity; ②study the change of the p46 (low/over expression/knockout) expression in microgravity environment and its influence on aIS and the related mechanism, which is to illustrate the response mechanism of aIS to the simulated microgravity environment. Ultimately, the mechanical and biological mechanisms of the inhibition of NK cell function by simulated microgravity will be revealed from a new angle of view that affecting the formation of aIS.

空间微重力抑制NK细胞杀伤活性，引起免疫功能下降，是载人航天领域亟待解决的重要难题，但目前机制未明。活化性免疫突触（aIS）是NK细胞发挥功能的必要结构，也是细胞骨架（可响应力学刺激）聚合重排的结构产物，因此aIS可能是NK细胞响应重力变化的关键元件。正常重力下NKp46（p46）调控骨架重排，促进aIS形成，申请人发现模拟微重力水平下p46表达显著下调，因此提出：微重力可能通过p46分子影响骨架重排，导致aIS形成受阻，进而抑制NK细胞功能。项目拟①模拟不同重力水平，研究重力变化对细胞骨架、弹性模量等aIS相关力学生物学特性及细胞功能的影响，明确aIS是NK细胞响应重力变化的关键效应结构；②研究p46（正常/高表达/敲除）在微重力水平下的表达、分布变化及其对aIS形成特性的影响及机制，阐明aIS响应微重力刺激的分子机制。最终从影响aIS形成角度揭示微重力抑制NK细胞功能的力学生物学机制。

空间微重力抑制NK细胞杀伤活性，引起免疫功能下降，是载人航天领域亟待解决的重要难题，但目前机制未明。活化性免疫突触（aIS）是NK细胞发挥功能的必要结构，也是细胞骨架（可响应力学刺激）聚合重排的结构产物，因此aIS可能是NK细胞响应重力变化的关键元件。正常重力下NKp46（p46）调控骨架重排，促进aIS形成，申请人发现模拟微重力水平下p46表达显著下调，因此提出：微重力可能通过p46分子影响骨架重排，导致aIS形成受阻，进而抑制NK细胞功能。项目①通过二维回转模拟微重力，研究重力变化对对aIS形成特性如aIS数量和状态、NK细胞形貌特征等的影响，以及aIS变化对NK细胞功能包括活化性受体、抑制性受体、杀伤颗粒等表达水平的影响。结果发现，模拟微重力显著降低NK细胞某些活化性受体的表达，显著抑制aIS的形成，进而抑制杀伤颗粒分泌，最终降低NK细胞杀伤功能。初步明确了aIS在NK细胞响应微重力过程中的关键作用。②通过构建NKp46高表达细胞株，研究NKp46在微重力水平下的表达、分布变化及其对aIS形成特性的影响及机制。结果发现微重力下NKp46显著下降，进而抑制下游CD3ζ、Grb2和Vav1等多种分子的表达，从而影响细胞骨架F-actin的聚合重排，导致aIS形成受阻，最终引起NK细胞杀伤活性显著降低。本项目最终从影响aIS形成角度揭示微重力抑制NK细胞功能的力学生物学机制，对于补充和完善力学环境下免疫细胞的抑制机理具有重要的科学意义，同时也为航天员乃至地面人群的免疫防护及治疗药物的开发提供理论依据。