Biology of the Eosinophilic Leukocyte

作为我们对嗜酸性粒细胞及其在宿主防御中作用的更大兴趣的一部分，我们与我在澳大利亚的同事一起探索了嗜酸性粒细胞在宿主防御中直接作用的可能性，以抵御流行的呼吸道病原体呼吸道合胞病毒(RSV)。具体地说，我们发现高嗜酸性粒细胞(IL-5转基因)小鼠比野生型小鼠更快地从肺组织中清除病毒，并且将嗜酸性粒细胞转移到RSV感染的野生型小鼠的肺中加速了病毒清除。在机制方面，我们证明了嗜酸性粒细胞表达识别病毒核酸的TLRs，在单链RNA刺激TLR7MyD88途径后被激活和脱颗粒，并提供对依赖于MyD88的RSV的宿主防御。总而言之，我们的结果表明，嗜酸性粒细胞可以在体内保护机体免受RSV的侵袭，因为它们促进了病毒的清除，从而可能限制病毒引起的肺功能障碍。这项工作的结果已被接受出版(Phips等人。《血色2007》(Bour 2007) 我们还继续探索嗜酸性粒细胞的分化和发育，特别是使用Yu及其同事的deltadblGATA嗜酸性粒细胞去除模型(JEM 2002)，在该模型中，转录因子GATA1的造血型启动子中回文增强子的缺失导致小鼠完全缺乏嗜酸性粒细胞。考虑到这些小鼠即使在Th2刺激的条件下也没有嗜酸性粒细胞，我们惊讶地发现，从deltadblGATA小鼠分离的骨髓前体细胞在体外受到细胞因子刺激时可以分化为成熟的嗜酸性粒细胞。培养的DeltadblGATA嗜酸性粒细胞含有免疫反应主要碱性蛋白的细胞质颗粒，它们表达表面Siglec F和编码主要碱性蛋白、嗜酸性粒细胞过氧化物酶和GATA1、2和3的转录本，其程度与培养的野生型嗜酸性粒细胞没有区别。成纤维细胞共培养和骨髓交叉移植实验表明，缺陷是一种内在的祖细胞缺陷，并且不受与基质细胞相互作用的影响。有趣的是，与野生型GATA1转录本相反，大多数来自培养的DeltadblGATA前体的GATA1转录本表达一个变异的GATA1转录本，其中包括第一个外显子1E(B)，位于前面描述的在造血细胞中发现的第一个外显子(1E(A))下游约3700bp和另一个变异第一外显子(1E(C))上游约42bp。综上所述，我们的数据表明，培养的祖细胞能够通过使用第二个更接近的启动子来规避deltadblGATA消融的影响，并利用这一机制产生大量支持嗜酸性粒细胞生长和分化的GATA1。这项工作的结果已被接受出版(Dyer等人。2007年。J.免疫，在新闻中)。 我还作为主要作者参与了发表在《过敏和临床免疫学杂志》(Rosenberg等人)上的一篇关于嗜酸性粒细胞和嗜酸性粒细胞贩运的综述。2007年，JACI119：13031310)，以及将在过敏和过敏性疾病，第2版，布莱克韦尔科学出版社发表的嗜酸性粒细胞一章的贡献者之一。 最后，我在嗜酸性粒细胞生物学和炎症方面的专业知识使我有机会作为编辑委员会的成员参加《血液》(自2003年以来)、《白细胞生物学杂志》(自1996年以来；晋升为副主编，2006年)、《临床与疫苗免疫学》(自2003年以来)和《1000生物学学院》(自2006年以来)。作为《血液》编辑委员会的一名成员，我有机会为几本介绍原始出版物(包括在参考书目中)的《内部血液胶囊》投稿。最近，我协助为《白细胞生物学杂志》撰写了一篇名为《关键进展》的原创专题，我还担任了采访编辑的角色。我们已经在2007财年发表了七篇这样的专题采访，这些采访已经成为该杂志的既定专题。

As part of our larger interest in eosinophils and their role in host defense, together with my colleagues in Australia, we have explored the possibility that eosinophils play a direct role in host defense against the prevalent respiratory pathogen, respiratory syncytial virus (RSV). Specifically, we found that virus clearance from lung tissue was more rapid in hypereosinophilic (interleukin5 transgenic) mice than in wild type mice, and that transfer of eosinophils to the lungs of RSVinfected wildtype mice accelerated virus clearance. In terms of mechanism, we demonstrated that eosinophils express TLRs that recognise viral nucleic acids, are activated and degranulate after ssRNA stimulation of the TLR7MyD88 pathway, and provide host defence against RSV that is MyD88dependent. Collectively, our results demonstrate that eosinophils can protect against RSV in vivo, as they promote virus clearance and may thus limit virusinduced lung dysfunction. The results of this work have been accepted for publication (Phipps et al. Blood 2007, in press). We have also continued our exploration of eosinophil differentiation and development, specifically using the deltadblGATA model of eosinophil ablation characterized by Yu and colleagues (JEM 2002) in which a deletion of a palindromic enhancer in the hematopoietic promoter of the transcription factor, GATA1, leads to mice that are completely devoid of eosinophils. Given that these mice are devoid of esoinophils even under conditions of profound Th2 stimulation, we were surprised to find that bone marrow progenitors isolated from deltadblGATA mice could differentiate into mature eosinophils when subjected to cytokine stimulation ex vivo. Cultured deltadblGATA eosinophils contain cytoplasmic granules with immunoreactive major basic protein and they express surface Siglec F and transcripts encoding major basic protein, eosinophil peroxidase, and GATA1, 2, and 3 to an extent indistinguishable from cultured wildtype eosinophils. Fibroblast coculture and bone marrow crosstransplant experiments indicate that the deficit is an intrinsic progenitor defect, and remains unaffected by interactions with stromal cells. Interestingly, and in contrast to those from the wild type, a majority of the GATA1 transcripts from cultured deltadblGATA progenitors express a variant GATA1 transcript that includes a first exon 1E(B), located approximately 3700 bp downstream to the previously described first exon found in hemopoietic cells (1E(A)) and approximately 42 bp upstream to another variant first exon, 1E(C). Taken together, our data suggest that cultured progenitors are able to circumvent the effects of the deltadblGATA ablation by using a second, more proximal, promoter and to use this mechanism to generate quantities of GATA1 that will support eosinophil growth and differentiation. The results of this work have been accepted for publication (Dyer et al. 2007. J. Immunol., in press). I also participated as lead author in a review of eosinophils and eosinophil trafficking published in Journal of Allergy and Clinical Immunology (Rosenberg et al. 2007, JACI 119:13031310) and among the contributors to the chapter Eosinophils to be published in Allergy and Allergic Disorders, 2nd edition, Blackwell Scientific Publishers. Finally, my expertise in eosinophil biology and inflammation has provided me with the opportunity to participate as a member of the Editorial Boards of Blood (since 2003), Journal of Leukocyte Biology (since 1996; promoted to Associate Editor, 2006), Clinical and Vaccine Immunology (since 2003) and Faculty of 1000 Biology (since 2006). As a member of the Editorial Board of Blood, I have been given the opportunity to contribute several Inside Blood capsules profiling original publications (included in bibliography). Most recently, I have assisted in developing an original feature for the Journal of Leukocyte Biology known as Pivotal Advance, and I have taken on the role of interviews editor. We have published seven of these feature interviews in FY2007, which have become an established feature in the journal.