The role of CXCR2-ligands for neutrophil mobilization from the bone marrow to peripheral sites

CXCR2-配体对于中性粒细胞从骨髓动员到外周部位的作用

• 批准号: 169104761
• 负责人: Professor Dr. Matthias Gunzer
• 金额: --
• 依托单位: Abteilung Entwicklungsbiologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/169104761?language=en
• 关键词: role; CXCR2; ligands; neutrophil; mobilization

The bone marrow is a major reserve for cells of the innate immune system, especially neutrophil granulocytes. From here these cells can be rapidly mobilized to the periphery by action of physiologic stimuli or peripheral inflammation. But they can also cause severe damage, e.g. in the initiation phase of cartilage-destructive diseases such as rheumatoid arthritis. However, how individual neutrophils behave within the bone marrow cavity during the process of mobilization or cartilage destruction and which impact peripheral inflammation has on the process is little understood. Using a newly developed intravital 2-photon microscopy approach in mice carrying a neutrophil-specific allele of EGFP we have shown that one of the major physiologic mobilizers, the hematopoietic cytokine G-CSF, acts by rapidly inducing the motility of individual neutrophils within the marrow cavity of the tibia. On a molecular level we found the increased expression of CXCL1 (KC) and CXCL2 (MIP-2), ligands for the chemokine receptor CXCR2, by marrow-resident megakaryocytes. Further, a blockade of CXCR2 by a specific antibody could block neutrophil mobilization by G-CSF. In a parallel study we have used a newly developed mouse model for the overexpression of IL17A selectively in the skin. This led to a phenotype highly reminiscent of human psoriasis, which was accompanied by massive infiltration of neutrophils into the skin together with strong neutrophilia in the bone marrow. We assume that also here the modulation of CXCL1 and 2 in the bone and also the skin play a major role for the increased frequency of neutrophils in the bone marrow and their recruitment to the skin. To investigate these concepts we propose to generate a novel mouse model in which the alleles for CXCL1 and 2 are made conditional within the same animal. In addition, the fluorescent protein Tomato will be engineered as a knockin into the CXCL1 locus to function as a reporter for promoter activity. Injecting these mice with G-CSF or inducing IL17A overexpression in the skin will show, which cells and with which kinetic produce CXCL1/2 in response to these diverse stimuli. Furthermore, the crossing of these mice to either megakaryocyte- or keratinocyte-specific Cre lines will allow deleting the CXCR2-ligands in a cell type specific manner. This will enable us to clarify, whether physiologic expression of CXCR2 ligands in either bone marrow-resident or peripheral cells is decisive for neutrophil recruitment by systemic G-CSF or skin-derived IL17A. Finally, we will use the mouse model of skin-specific IL17A-overexpression to study bone loss and joint inflammation mediated by excess production of neutrophils in the bone marrow, which are two well known entities accompanying psoriatic skin disease. Collectively this study should provide us with a previously not available knowledge on the physiology and pathophysiology of neutrophils in the bone marrow and the periphery and the role of CXCR2-ligands for these processes, thus a very central mechanism of cellular osteoimmunology.

骨髓是先天免疫系统细胞的主要储备，尤其是中性粒细胞。从这里，这些细胞可以通过生理刺激或外周炎症的作用迅速动员到外周。但它们也可能导致严重的损伤，例如在软骨破坏性疾病如类风湿性关节炎的起始阶段。然而，在动员或软骨破坏过程中，单个中性粒细胞在骨髓腔内的行为以及外周炎症对该过程的影响却知之甚少。使用一种新开发的活体2-光子显微镜的方法在小鼠携带一个嗜中性粒细胞特异性等位基因的EGFP，我们已经表明，一个主要的生理动员，造血细胞因子G-CSF，通过快速诱导单个中性粒细胞的胫骨骨髓腔内的运动。在分子水平上，我们发现骨髓巨核细胞趋化因子受体CXCR 2的配体CXCL 1（KC）和CXCL 2（MIP-2）的表达增加。此外，特异性抗体对CXCR 2的阻断可以阻断G-CSF对中性粒细胞的动员。在一项平行研究中，我们使用了一种新开发的小鼠模型，用于在皮肤中选择性地过表达IL 17 A。这导致了一种非常类似于人类银屑病的表型，其伴随着大量中性粒细胞浸润到皮肤中以及骨髓中的强烈嗜中性粒细胞。我们假设，在这里，骨和皮肤中的CXCL 1和2的调节对于骨髓中中性粒细胞的频率增加及其向皮肤的募集也起主要作用。为了研究这些概念，我们提出了一种新的小鼠模型，其中CXCL 1和2的等位基因在同一动物中是有条件的。此外，荧光蛋白Tomato将作为敲入CXCL 1基因座的基因工程，作为启动子活性的报告基因。给这些小鼠注射G-CSF或在皮肤中诱导IL 17 A过表达将显示哪些细胞和哪些动力学产生CXCL 1/2以响应这些不同的刺激。此外，这些小鼠与巨核细胞或角质形成细胞特异性Cre系的杂交将允许以细胞类型特异性方式缺失CXCR 2配体。这将使我们能够澄清，无论是骨髓驻留或外周细胞中的CXCR 2配体的生理表达是决定性的中性粒细胞募集全身G-CSF或皮肤来源的IL 17 A。最后，我们将使用皮肤特异性IL 17 A过表达的小鼠模型来研究骨髓中中性粒细胞过量产生介导的骨丢失和关节炎症，这是伴随银屑病皮肤病的两个众所周知的实体。总的来说，这项研究应该为我们提供以前没有的知识，在骨髓和外周的中性粒细胞的生理和病理生理学和CXCR 2配体的作用，这些过程中，因此一个非常核心的机制，细胞骨免疫。