IL-10 Controls Mast Cell Homeostasis

描述(申请人提供)：肥大细胞驻留在宿主-环境界面，在保护性和病理反应中充当免疫哨兵。高亲和力的IgE受体Fc？RI是人们最了解的肥大细胞激活途径。肥大细胞的动态平衡可能是由炎症反应中产生的细胞因子调节的，可能是以自分泌的方式。我们证明，IL-10通过靶向Fyn、Stat5和Akt的降解来抑制Fc？RI介导的激活。重要的是，这种抑制在Th1倾向的C57BL/6小鼠的肥大细胞中观察到，但在Th2倾向的BALB/c或129/Sv小鼠中观察到。IL-10的敏感性与针对Fyn、Stat5B和Akt的microRNAs(MiRs)的诱导有关。虽然已知Fyn激活Akt，但对Stat5的作用知之甚少。我们发现Stat5B在Fc？RI诱导的细胞因子产生中起关键作用。我们证明了Stat5酪氨酸磷酸化是依赖于Fyn的，并且Fyn与Stat5在物理上相互作用。在IgE信号转导过程中，Stat5也通过Fyn非依赖的途径被丝氨酸磷酸化。我们将确定IL-10如何调节Fyn-Stat5/Akt通路，以及对这种抑制的抵抗是否与过敏性疾病相关。我们的假设是，Fc？RI的激活受到反馈信号的限制，反馈信号通过IL-10诱导的miRs选择性地抑制Fyn-Stat5/Akt通路。在不允许的遗传背景下失去这一调节可能是特应性病因的一部分。具体目的1.验证IL-10通过对肥大细胞和嗜碱性粒细胞miR诱导的基因限制性作用而拮抗Fyn-Stat5/Akt通路的假说。2.验证Stat5B在肥大细胞和嗜碱性粒细胞中对Fc？RI信号转导起关键作用的假设。III.验证IL-10通过拮抗Fyn-Stat5/Akt通路抑制体内Fc？RI反应的假说。

DESCRIPTION (provided by applicant): Mast cells reside at the host-environment interface, serving as immune sentinels in both protective and pathological responses. The high affinity IgE receptor, Fc?RI, is the best-understood mast cell-activating pathway. Mast cell homeostasis is likely regulated by cytokines produced in the inflammatory response, perhaps in an autocrine fashion. We demonstrate that IL-10 suppresses Fc?RI-mediated activation by targeting Fyn, Stat5, and Akt for degradation. Importantly, this suppression is observed in mast cells from Th1-prone C57BL/6 but not Th2-prone BALB/c or 129/Sv mice. IL-10 sensitivity correlates with the induction of microRNAs (miRs) potentially targeting Fyn, Stat5B, and Akt. While Fyn is known to activate Akt, the role of Stat5 is less understood. We find that Stat5B is critical for Fc?RI-induced cytokine production. We demonstrate that Stat5 tyrosine phosphorylation is Fyn-dependent and that Fyn physically interacts with Stat5. Stat5 is also serine phosphorylated during IgE signaling, through a Fyn-independent pathway. We will determine how the Fyn-Stat5/Akt pathway is regulated by IL-10, and if resistance to this suppression correlates with allergic disease. Our hypothesis is that Fc?RI activation is limited by feedback signaling via IL-10-induced miRs that selectively dampen the Fyn-Stat5/Akt pathway. Loss of this regulation in a non-permissive genetic background could be part of atopic etiology. Specific Aims I. To test the hypothesis that IL-10 antagonizes the Fyn-Stat5/Akt pathway via genotype-restricted effects on miR induction in mast cells and basophils. II. To test the hypothesis that Stat5B is critical for Fc?RI signaling in mast cells and basophils. III. To test the hypothesis that IL-10 suppresses Fc?RI responses in vivo by antagonizing the Fyn-Stat5/Akt pathway.