Neutrophils self-limit swarming to contain bacterial growth in vivo.
Neutrophils self-limit swarming to contain bacterial growth in vivo.
复制标题
DOI：
10.1126/science.abe7729
复制
发表时间：
2021-06-18
期刊：
影响因子：
--
通讯作者：
Lämmermann T
中科院分区：
文献类型：
--
作者：
Kienle K;Glaser KM;Eickhoff S;Mihlan M;Knöpper K;Reátegui E;Epple MW;Gunzer M;Baumeister R;Tarrant TK;Germain RN;Irimia D;Kastenmüller W;Lämmermann T
中性粒细胞相互交流，在受感染的器官中形成群体。这种群体反应的协调对于消除细菌和真菌至关重要。利用转基因小鼠，我们发现中性粒细胞已经进化出一种内在机制来自我限制蜂群，避免炎症期间不受控制的聚集。G蛋白偶联受体（GPCR）脱敏作为一种负反馈控制，当中性粒细胞感知到高浓度的自我分泌引诱剂时，它们会在最初放大蜂群，从而阻止中性粒细胞的迁移。对这一过程的干扰使中性粒细胞能够扫描更大的组织区域寻找微生物。出乎意料的是，这不利于细菌的清除，因为中性粒细胞集群对增殖细菌的遏制变得受阻。我们的数据揭示了自动信号如何阻止自组织的群体行为，以及中性粒细胞趋化性和阻滞的精细平衡如何抵消细菌的逃逸。中性粒细胞群的自组织。上图：成群的中性粒细胞通过释放对邻近中性粒细胞起作用的引诱剂，向组织损伤或细菌入侵的部位自我放大其高度趋化性的招募。中性粒细胞显示为带有迁移轨迹的球体（右）。下图：同一种细胞分泌的引诱剂在局部积聚时阻止中性粒细胞积聚并形成簇状，这一过程对控制感染组织中的细菌很重要。细胞和昆虫的集体行为往往依赖于自组织过程。通过释放引诱物信号，少数个体可以启动整个种群的积累和聚集。中性粒细胞是先天免疫反应的关键角色，大量浸润炎症和感染组织。这些细胞利用这种正反馈放大来发现并杀死组织中的细菌。中性粒细胞通过邻近细胞上的细胞表面表达的G蛋白偶联受体（gpcr）分泌吸引剂，利用这种细胞间交流的形式，作为一个群体协调它们对病原体的搜寻。如何终止这种群集反应以避免不受控制的中性粒细胞积聚和防止过度炎症目前尚不清楚。哺乳动物组织中中性粒细胞聚集的停止信号尚未确定。它们可能来源于周围炎症环境的细胞或中性粒细胞本身。我们推断，中性粒细胞释放的引诱剂可能高度集中在这些细胞聚集较多的地方。高化学引诱剂浓度可以通过称为GPCR脱敏的过程减弱细胞反应。我们假设了群集的自我限制机制：在早期阶段放大群集的相同中性粒细胞表达的引诱剂的局部积累会导致中性粒细胞群集后期各自gpcr的脱敏。因此，我们研究了GPCR脱敏在中性粒细胞组织导航和宿主防御中的作用。我们培养了中性粒细胞缺乏GPCR激酶（GRKs）的小鼠菌株，GRKs是介导GPCR脱敏过程的关键酶。在测试的四种GRK亚型中，体外实验发现GRK2是对被群体释放的引诱剂（LTB4和CXCL2）激活的gpcr脱敏所必需的激酶。当中性粒细胞在体外感受到高浓度的群体引诱剂时，GRK2会使相应的受体脱敏，从而诱导迁移停止。损伤皮肤和感染淋巴结的双光子活体成像显示，GRK2和GPCR脱敏在生理组织中性粒细胞聚集过程中起关键作用。在嗜中性粒细胞聚集和自我产生高群体引诱剂浓度的局部场的位置，GPCR脱敏是阻止嗜中性粒细胞迁移阻滞的关键。抗脱敏的中性粒细胞移动速度更快，并探索感染铜绿假单胞菌的淋巴结组织的更大区域。这种行为表明，在整个感染器官中进行细菌采样更有效。令人惊讶的是，grk2缺陷的中性粒细胞小鼠表现出受损而不是改善的细菌清除。这一发现不能用抗菌效应物功能的改变来解释。体外实验对蜂群行为和细菌生长进行了详细分析，结果表明，GPCR对蜂群引诱剂的脱敏需要诱导中性粒细胞阻滞，以实现最佳的细菌吞噬和蜂群控制。我们描述了感染组织中中性粒细胞集体自组织的细胞内在停止机制，该机制基于感知在早期阶段放大群体的相同细胞分泌引诱剂的局部积累。GPCR脱敏作为一种负反馈控制机制来阻止中性粒细胞在群体聚集中的迁移。这种导航机制允许中性粒细胞在形成群体时自我限制其动态，并确保最佳的细菌消除。对自我产生的激活信号的脱敏作为一种自组织原理对于免疫宿主防御细菌是重要的，并且可能在细胞和昆虫中通知其他类别的集体行为。
Neutrophils communicate with each other to form swarms in infected organs. Coordination of this population response is critical for the elimination of bacteria and fungi. Using transgenic mice, we found that neutrophils have evolved an intrinsic mechanism to self-limit swarming and avoid uncontrolled aggregation during inflammation. G protein–coupled receptor (GPCR) desensitization acts as a negative feedback control to stop migration of neutrophils when they sense high concentrations of self-secreted attractants that initially amplify swarming. Interference with this process allows neutrophils to scan larger tissue areas for microbes. Unexpectedly, this does not benefit bacterial clearance as containment of proliferating bacteria by neutrophil clusters becomes impeded. Our data reveal how autosignaling stops self-organized swarming behavior and how the finely tuned balance of neutrophil chemotaxis and arrest counteracts bacterial escape. Self-organization of neutrophil swarms. Top: Swarming neutrophils self-amplify their highly chemotactic recruitment toward sites of tissue injury or bacterial invasion by releasing attractants that act on neighboring neutrophils. Neutrophils are displayed as spheres with migration tracks (right). Bottom: The local accumulation of the same cell-secreted attractants stops neutrophils when they accumulate and form clusters, a process important for the containment of bacteria in infected tissues. The collective behavior of cells and insects often relies on self-organizing processes. By releasing attractant signals, a few individuals can initiate the accumulation and aggregation of a whole population. Neutrophils, key players in the innate immune response, infiltrate inflamed and infected tissues in large numbers. These cells make use of such positive feedback amplification to find and kill bacteria in tissues. By secreting attractants that act through cell surface–expressed G protein–coupled receptors (GPCRs) on neighboring cells, neutrophils use this form of intercellular communication and coordinate their hunt for pathogens as a swarm. How this swarming response is terminated to avoid uncontrolled neutrophil accumulations and prevent excessive inflammation is currently unknown. The stop signals for neutrophil swarming in mammalian tissues have not yet been defined. They may be derived from cells of the surrounding inflammatory environment or from neutrophils themselves. We reasoned that the attractants released by neutrophils may become highly concentrated at sites where these cells cluster in larger numbers. It is well established that high chemoattractant concentrations can attenuate cellular responses by a process termed GPCR desensitization. We hypothesized a self-limiting mechanism for swarming: The local accumulation of the same neutrophil-expressed attractants that amplify swarming during early stages would cause desensitization of their respective GPCRs at later stages of neutrophil clustering. This led us to investigate the role of GPCR desensitization in neutrophil tissue navigation and host defense. We generated mouse strains whose neutrophils were deficient in GPCR kinases (GRKs), critical enzymes for mediating the GPCR desensitization process. Of the four GRK isoforms tested, in vitro experiments identified GRK2 as the kinase necessary to desensitize GPCRs activated by swarm-released attractants (LTB4 and CXCL2). When neutrophils sense high concentrations of swarm attractants in vitro, GRK2 desensitizes the corresponding receptors to induce migration arrest. Two-photon intravital imaging of injured skin and infected lymph nodes of mice showed that GRK2 and GPCR desensitization play critical roles during neutrophil swarming in physiological tissue. At sites where swarming neutrophils accumulate and self-generate local fields of high swarm attractant concentration, GPCR desensitization was crucial to stop neutrophil migration arrest. Desensitization-resistant neutrophils moved faster and explored larger areas of lymph node tissue infected with the bacterium Pseudomonas aeruginosa. Such behavior suggested more effective bacterial sampling throughout the infected organ. Surprisingly, mice with GRK2-deficient neutrophils showed impaired rather than improved bacterial clearance. This finding could not be explained by altered antibacterial effector functions. In vitro assays for the detailed analysis of swarming behavior and bacterial growth revealed that GPCR desensitization to swarm attractants is required to induce neutrophil arrest for optimal bacterial phagocytosis and containment in swarm clusters. We describe a cell-intrinsic stop mechanism for the self-organization of neutrophil collectives in infected tissues, which is based on sensing the local accumulation of the same cell-secreted attractants that amplify swarming during early stages. GPCR desensitization acts as a negative feedback control mechanism to stop neutrophil migration in swarm aggregates. This navigation mechanism allows neutrophils to self-limit their dynamics within forming swarms and ensures optimal elimination of bacteria. Desensitization to a self-produced activation signal as a principle of self-organization is important for immune host defense against bacteria, and likely informs other categories of collective behavior in cells and insects.
登录
查看更多内容
影响因子：
7.8
作者：
Foxman, E F;Campbell, J J;Butcher, E C
通讯作者：
Butcher, E C
影响因子：
82.9
作者：
Fan, J;Malik, AB
通讯作者：
Malik, AB
影响因子：
64.5
作者：
Kastenmüller W;Torabi-Parizi P;Subramanian N;Lämmermann T;Germain RN
通讯作者：
Germain RN
影响因子：
64.8
作者：
Guo, Xiaojiao;Yu, Qiaoqiao;Kang, Le
通讯作者：
Kang, Le
影响因子：
4.4
作者：
Kavelaars, A;Vroon, A;Heijnen, CJ
通讯作者：
Heijnen, CJ