Biology of the NK cell cytolytic activity rhythm

昼夜节律和日常节律调节着生理和行为的许多方面。尽管越来越多的研究表明，昼夜节律紊乱可能使生物体更容易受到感染和癌症，但昼夜节律系统和免疫系统之间的分子联系在很大程度上是未知的。自然杀伤（NK）细胞的细胞溶解活性已被证明遵循每日节律，这是在昼夜节律控制下的。NK细胞参与对抗病毒感染和癌症的免疫反应。本研究采用大鼠动物模型，确定了脾NK细胞细胞溶解功能的昼夜节律调控机制。它验证了脾NK细胞具有分子钟的假设，这些分子钟可以协调细胞溶解因子的节律性表达，从而驱动NK细胞细胞溶解功能的昼夜节律。下丘脑视上核本身受光输入的影响，通过改变交感神经向脾NK细胞的流出来协调时钟调节基因的表达。本研究采用磁分离技术分离脾脏NK细胞群，测定细胞毒性因子、细胞因子和时钟基因的变化；采用NK细胞基因敲低技术研究时钟基因对细胞溶解功能的影响；分析nk敏感肿瘤细胞清除的昼夜变化；确定NK细胞功能对时差的易感性，这是一种常见的昼夜节律中断，并使用药理学工具研究脾脏和克隆NK细胞中重设生物钟的关键信号机制。提出的一系列研究应该增强我们对协调NK细胞昼夜节律功能的生理机制的认识。

Circadian and daily rhythms regulate many aspects of physiology and behavior. Although a growing number of studies suggest that circadian disruptions may render organisms more susceptible to infection and cancer, the molecular links between the circadian system and the immune system are largely unknown. Natural killer (NK) cell cytolytic activity has been shown to follow a daily rhythm, which is under a circadian control. NK cells participate in the immune response against viral infections and cancer. Employing the rat animal model, this proposal determines the mechanisms by which the circadian rhythm of splenic NK cell cytolytic function is regulated. It tests the hypothesis that splenic NK cells are provided with molecular clocks that orchestrate the rhythmic expression of cytolytic factors that drive the circadian rhythm of NK cell cytolytic function. The hypothalamic suprachaismatic nucleus, which is itsetf, entrained by photic input, coordinates the expression of clock regulatory genes by altering the sympathetic outflow to the splenic NK cells. The proposed research uses magnetic separation techniques to isolate the NK cell population from the spleen to determine the changes in cytotoxic factors, cytokines and clock genes in these cells; employs gene knockdown techniques in NK cells to study the influence Of clock genes on cytolytic function; analyzes the circadian variations in the clearance of NK-sensitive tumor cells; determines the susceptibility of NK cell function to jet lag, a common circadian disruption, and uses pharmacological tools to investigate the signaling mechanism critically involved in resetting the circadian clock in splenic and clonal NK cells. The proposed series of studies should enhance our knowledge of the physiological mechanisms orchestrating NK cell circadian function.