Biology of the Eosinophilic Leukocyte

在本报告年度，我们继续探索嗜酸性粒细胞及其与呼吸道病毒病原体的相互作用。我们的新型嗜酸性粒细胞培养系统，从未选择的小鼠骨髓祖细胞中产生大量高纯度（约95%）的细胞（Dyer等）。J Immunol. 2008)，促进了这一正在进行的努力。在最近发表的一篇文章中（Dyer et al.）。BLOOD， 2009年出版)我们证明了人和小鼠嗜酸性粒细胞分别作为肺炎病毒病原体呼吸道合胞病毒（RSV）和小鼠肺炎病毒（PVM）感染的靶标，并且病毒感染引发疾病相关的促炎介质的释放，包括几种趋化因子和细胞因子IL-6。最有趣的是，与rsv攻击小鼠肺组织的研究结果相反，在缺乏tlr信号适配器MyD88的小鼠嗜酸性粒细胞中，PVM复制加速，同时介质释放减少。进一步研究，我们发现外源性IL-6抑制MyD88基因缺失的嗜酸性粒细胞中的病毒复制，表明MyD88依赖性细胞因子介导的反馈回路在调节这种反应中起作用。综上所述，我们的研究结果表明嗜酸性粒细胞可以作为生产性病毒感染的靶标，因此可能对肺炎病毒疾病的发病机制和解决有多种复杂的贡献。

During this reporting year, we have continued our exploration of eosinophils and their interactions with respiratory virus pathogens. Our novel eosinophil culture system, which generates large numbers of cells at high purity (>95%) from unselected mouse bone marrow progenitors (Dyer et al. J Immunol. 2008), has facilitated this ongoing effort. In a recent publication (Dyer et al. BLOOD, 2009 in press) we demonstrated that both human and mouse eosinophils serve as targets for infection by the pneumovirus pathogens, respiratory syncytial virus (RSV) and pneumonia virus of mice (PVM), respectively, and that virus infection elicits the release of disease-related proinflammatory mediators, including several chemokines and the cytokine, IL-6. Most interesting, and in contrast to the findings reported in lung tissue of RSV-challenged mice, PVM replication is accelerated in mouse eosinophils that are devoid of the TLR-signaling adapter, MyD88, and mediator release is diminished concomittantly. Pursuing this further, we found that exogenous IL-6 suppresses virus replication in MyD88 gene-deleted eosinophils, suggesting a role for a MyD88-dependent cytokine-mediated feedback circuit in modulating this response. Taken together, our findings indicate that eosinophils can serve as targets for productive virus infection, and thus may have varied and complex contributions to the pathogenesis and resolution of pneumovirus disease. Another signinficant study on this topic focused on the role of eosinophils elicited in response to vaccination with formalin-fixed pneumonia virus of mice (PVM), a paradigm that is analogous to the Th2-mediated enhanced disease described in response to inactivated RSV vaccines. We demonstrated that PVM infection in mice vaccinated with formalin-inactivated Ags from PVM-infected cells (PVM Ags) yields Th2-skewed hypersensitivity, analogous to that observed in response to hRSV, including elevated levels of IL-4, IL-5, IL-13, and eosinophils in bronchoalveolar lavage fluid of PVM-infected mice that were vaccinated with PVM Ags, but not among mice vaccinated with formalin-inactivated Ags from uninfected cells (control Ags). Interestingly, infection in PVM Ag-vaccinated mice was associated with an approximately 10-fold reduction in lung virus titer and protection against weight loss when compared with infected mice vaccinated with control Ags, despite the absence of serum-neutralizing Abs, although followup studies with eosinophil deficient demonstrated, seemingly paradoxically, that eosinophil deficiency had no impact on virus titer or clinical symptoms in PVM Ag-vaccinated mice. We are exploring the nature of the eosinophil-activation state as a crucial feature in its ability to promote virus clearance in vivo (Percopo et al. J Immunol., 2009) We have also published a paper that explores the impact of two parallel isolation methods on eosinophil function and viability in culture (Percopo et al. Exp Dermatol., 2009, in press). We generated these findings in response to an earlier publication in this same journal that reported that negatively-selected eosinophils isolated with multi-antibody bead kits were dysfunctional and underwent rapid apoptosis in culture. We found completely contrasting results, specifically, that multi-antibody eosinophil isolation represents a substantial advantage over traditional anti-CD-16 microbeads when isolating large numbers of eosinophils from concentrated leukocyte preparations, and most important, no differential survival or premature apoptosis was observed. Another publication (Qiu et al. J Biol Chem., 2009) delineates the role of GATA factors in promoting transcription of the eosinophil-derived neurotoxin (EDN), also known as the RNase A ribonuclease, RNase 2. This study is discussed in detail in AI000942-06. Finally, I contributed my expertise in eosinophil biology and evolution to a primate pathology study headed by Dr. Alfonso Gozalo, CMB, NIAID, which resulted in a publication (Gozalo et al. JAALAS 2009). To our knowledge, this report is the first description of presumptive hypereosinophilic syndrome in a nonhuman primate. During this reporting period, I authored two significant reviews. The first was an invited review featuring our work on interactions of eosinophils with respiratory virus pathogens (Rosenberg et al., Immunol Res., 2009), and the second, on a similar topic, a more in-depth peer-reviewed consideration of the field (Rosenberg et al., Antiviral Res., 2009). 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), Clinical and Vaccine Immunology (since 2003) and Faculty of 1000 Biology (since 2006).