Functional and Epigenetic Analysis of Th2 Heterogeneity

T细胞的一个子集，称为Th 2细胞，是产生过敏性免疫反应所必需的。Th 2细胞表达三种标志性细胞因子，IL-4、IL-5和IL-13，每种细胞因子对过敏性病理都有特异性贡献。IL-4驱动Th 2分化并在抗体类别转换为IgE中起主导作用，IL-5是主要的嗜酸性粒细胞活性细胞因子，IL-13通过其上调粘附分子和趋化因子驱动富含嗜酸性粒细胞的组织炎症。 我们假设Th 2谱系内的异质性将产生具有不同细胞因子表达、效应子功能和在疾病发病机制中的作用的Th 2亚群。使用多色流式细胞术，我们发现两个占主导地位的亚群内的人CD 4 Th 2区室：IL-5-Th 2细胞，共表达IL-4和IL-13，和IL-5+ Th 2细胞，表达所有三个Th 2细胞因子。这两个群体的Th 2细胞可以直接证明离体以及在T细胞克隆和短期线。值得注意的是，从非过敏性受试者直接离体分离的Th 2细胞中只有15%是IL-5+ Th 2细胞。IL-5+ Th 2细胞表现出高度分化的记忆性T细胞的表型标记，表明IL-5+和IL-5-Th 2细胞分别是或多或少高度分化的Th 2细胞。我们进一步验证了这一假设，通过检查在体外Th 2分化的一系列轮次的Th 2细胞因子的共表达。到第二轮，三分之二的细胞表达IL-4或IL-13，但<10%的细胞表达IL-5。在分析的5轮中的每一轮中，相对于IL-5-Th 2表型，存在一致且显著延迟的IL-5+获得。两个Th 2亚群的微阵列转录谱分析揭示了IL-5-和IL-5 + Th 2亚群之间约150个差异表达的基因。 总之，这些发现表明Th 2细胞由两个亚群组成：IL-5+和IL-5-Th 2细胞，并且IL-5+ Th 2细胞代表高度分化的Th 2细胞的表型上不同的亚群。这些结果表明，IL-5+ Th 2细胞具有不同的功能特性比IL-5-Th 2细胞，并可能作出独特的贡献过敏性炎症。了解IL-5基因调控对于开发针对嗜酸性粒细胞炎症的有效策略非常重要。

A subset of T cells, termed Th2 cells, is required for the generation of allergic immune responses. Th2 cells express three signature cytokines, IL-4, IL-5, and IL-13, each of which makes a specific contribution to allergic pathology. IL-4 drives Th2 differentiation and plays a dominant role in antibody class switching to IgE, IL-5 is the major eosinophil active cytokine, and IL-13 drives eosinophil-rich tissue inflammation though its upregulation of adhesions molecules and chemokines. We hypothesized heterogeneity within the Th2 lineage would yield Th2 subpopulations with different cytokine expression, effector functions and roles in disease pathogenesis. Using polychromatic flow cytometry, we found two dominant subpopulations within the human CD4 Th2 compartment: IL-5- Th2 cells, which co-expressed IL-4 and IL-13, and IL-5+ Th2 cells, which expressed all three Th2 cytokines. These two populations of Th2 cells could be demonstrated directly ex vivo as well as in T cell clones and short-term lines. Notably, only 15% of the Th2 cells isolated directly ex vivo from non-allergic subjects were IL-5+ Th2 cells. IL-5+ Th2 cells exhibited phenotypic markers of highly differentiated memory T cells, suggesting that the IL-5+ and IL-5- Th2 cells are more and less highly differentiated Th2 cells, respectively. We further tested this hypothesis by examining Th2 cytokine coexpression during serial rounds of in vitro Th2 differentiation. By the second round, two-thirds of the cells expressed IL-4 or IL-13, but <10% of the cells expressed IL-5. In each of the 5 rounds analyzed, there was a consistent and markedly delayed acquisition of the IL-5+ relative to the IL-5- Th2 phenotype. Microarray transcription profiling of the two Th2 subpopulations revealed approximately 150 differentially expressed genes between the IL-5- and IL5+ Th2 subpopulations. In summary, these findings demonstrate that Th2 cells consist of two subpopulations: IL-5+ and IL-5- Th2 cells, and that IL-5+ Th2 cells represent a phenotypically distinct subpopulation of highly differentiated Th2 cells. These results suggest that IL-5+ Th2 cells have different functional properties than IL-5- Th2 cells and may make a unique contribution to allergic inflammation. Understanding IL-5 gene regulation is important in developing effective strategies targeting eosinophilic inflammation.