Identification and characterization of activated genes of eosinophils in asthma

由特异性抗原引起的过敏性晚期反应与抗原给药部位的嗜酸性粒细胞浸润有关。虽然已知IL-5对抗原诱导的嗜酸性粒细胞募集到组织中起重要作用，并且IL-5激活Stat 5a和Stat 5 b，但关于嗜酸性粒细胞中IL-5的靶基因以及Stat 5a和Stat 5 b在抗原诱导的IL-5依赖性嗜酸性粒细胞募集到组织中的作用是未知的。在本研究中，我们针对这些问题，首先，我们采用代表性差异分析（RDA）来鉴定人嗜酸性粒细胞中IL-5诱导的基因。我们发现，除了已知的IL-5信号传导靶点，如CIS和Bcl-X，我们从RDA克隆中克隆了8个新基因。通过北方印迹法证实了8个基因中的5个与IL-5诱导的嗜酸性粒细胞基因表达有关。目前，我们正试图从嗜酸性粒细胞cDNA文库中筛选出全长cDNA。因此，我们相信，对嗜酸性粒细胞IL-5信号转导靶基因的鉴定将有助于揭示嗜酸性粒细胞的发生机制以及哮喘等过敏性疾病的发病机制。其次，我们分析了Stat 5a缺陷（Stat 5a ^<-/->）和Stat 5 b缺陷（Stat 5 b ^<-/->）小鼠的过敏特性。我们发现抗原诱导的嗜酸性粒细胞向气道的募集和BALF中IL-5的产生在Stat 5a ^<-/->小鼠和Stat 5 b ^<-/->小鼠中严重减少。此外，IL-5诱导的嗜酸性粒细胞生成在Stat 5a ^<-/->小鼠和Stat 5 b ^<-/->小鼠中也受损。这些结果表明，Stat 5a和Stat 5 b是诱导抗原诱导的嗜酸性粒细胞募集到气道中所必需的，并且Stat 5a ^<-/->小鼠和Stat 5 b ^<-/->小鼠中抗原诱导的嗜酸性粒细胞募集的缺陷是由气道中IL-5产生受损和嗜酸性粒细胞的IL-5反应性降低引起的。

Allergic late-phase reactions provoked by specific antigens are associated with intense eosinophil infiltration into the site of antigen administration. While it is known that IL-5 plays an important role for antigen-induced eosinophil recruitment into the tissue and that IL-5 activates Stat5a and Stat5b, it is unknown about target gene (s) of IL-5 in eosinophils as well as a role of Stat5a and Stat5b in antigen-induced, IL-5-dependent eosinophil recruitment into the tissue. In this study, we addressed these points.First, to identify IL-5-inducible genes in human eosinophils, we employed Representational Difference Analysis (RDA). We found that, in addition to known targets of IL-5 signaling, such as CIS and Bcl-X, we cloned 8 novel genes from RDA clones. Five out of 8 genes were confirmed for the IL-5-induced gene expression in eosinophils by northern blotting. At present, we are trying to fish out full length cDNAs from eosinophil cDNA library. In future, we believe that the identification of target genes of IL-5 signaling in eosinophils will uncover the mechanisms of eosinophil development and the pathogenesis of allergic diseases such as asthma.Second, we analyzed the allergic properties of Stat5a-deficient (Stat5a^<-/->) and Stat5b-deficient (Stat5b^<-/->) mice. We found that antigen-induced eosinophil recruitment into the airways and IL-5 production in BALF were severely decreased in Stat5a^<-/-> mice and Stat5b^<-/-> mice. In addition, IL-5-induced eosinophilopoiesis was also impaired in Stat5a^<-/-> mice and Stat5b^<-/-> mice. These results indicate that bath Stat5a and Stat5b are essential for induction of antigen-induced eosinophil recruitment into the airways and that the defects in antigen-induced eosinophil recruitment in Stat5a^<-/-> mice and Stat5b^<-/-> mice result from both impaired IL-5 production in the airways and diminished IL-5 responsiveness of eosinophils.