The function and regulation of IL-33 in mast cell activation

背景：IL-33是IL-1细胞因子家族的一员，是肥大细胞的重要激活因子。全长IL-33是一种生物活性细胞因子；然而，肥大细胞蛋白酶通过切割中心结构域来处理该分子，释放il -1样细胞因子结构域，从而将其生物活性提高约30倍。最小的IL-33受体复合物由IL-1R4（也称为ST2或IL-33Ra）和IL-1R3 （IL-1RAcP）链组成。在肥大细胞中，IL-33R复合物的独特之处在于它与受体酪氨酸激酶c-Kit相关。这传递了强大的协同受体串扰，并进一步增加了il -33介导的反应的复杂性。最近的证据表明，IL-33的活性依赖于嘌呤能p2受体（P2R）的激活。在肥大细胞中，ATP-P2R通路已被证明具有中枢激活和促炎作用，而抑制肥大细胞中P2R的表达可维持组织稳态。此外，我们最近发现腺苷信号通过嘌呤能P1受体（A3）降低IL-33R的表达，抑制IL-33引起的IgE增强和抗原诱导的脱颗粒。这表明肥大细胞中IL-33活性的相互和动态控制依赖于ATP和ADP的产生和代谢。目前尚不清楚IL-33/P1R-和p2r诱导的人肥大细胞激活和随后的介质释放是否是受体串扰的结果，更不用说这种活性背后的分子机制了。主要目标：项目的目标是：1。研究人类肥大细胞被IL-33单独激活以及与ATP/ADP途径协同激活的方式，并确定IL-33诱导分泌组的性质。2 .研究IL-33对肥大细胞P1和P2受体表达模式的影响，以及ATP/ADP通路对人肥大细胞IL-33R表达和IL-33蛋白加工和信号转导的相互作用。研究通过IL-33与ATP/ADP协同作用激活人肥大细胞对人先天淋巴细胞（ILC） 2行为的影响。潜在结果：该研究可能为IL-33对人肥大细胞活性的生物学基础提供新的认识。培训：在方法上，该项目将包括培养和分化人类肥大细胞和其他细胞系，并通过最先进的流式细胞术、先进的免疫荧光、转录组学分析、深度免疫表型和代谢/蛋白质组学方法评估其功能。

Background: IL-33, a member of the IL-1 cytokine family, is a crucial activator of mast cells. Full length IL-33 is a bioactive cytokine; however, mast cell proteases process this molecule by cleaving the central domain to release an IL-1-like cytokine domain, which increases its biological activity approximately 30-fold. The minimal IL-33 receptor complex is composed of the IL-1R4 (also known as ST2 or IL-33Ra) and the IL-1R3 (IL-1RAcP) chain. In mast cells the IL-33R complex is unique in that it associates with the receptor tyrosine kinase c-Kit. This conveys strong synergistic receptor crosstalk and adds a further level of complexity to IL-33-mediated responses. Recent evidence suggests that IL-33 activities are dependent on purinergic P2-receptor (P2R) activation. In mast cells, the ATP-P2R pathway has been shown to have a central activating and pro-inflammatory role, while inhibition of P2R expression on mast cells maintains tissue homeostasis. In addition, we have recently shown that adenosine signalling via the purinergic P1 receptor (A3) decreases IL-33R expression and inhibits the IL-33 provoked potentiation of IgE and antigen induced degranulation. This suggests a reciprocal and dynamic control of IL-33 activity in mast cells dependent on the production and metabolism of ATP and ADP. It is currently unknown if the IL-33/P1R- and P2R-induced human mast cell activation and consequent release of mediators is the result of receptor crosstalk let alone what the molecular mechanisms underlying this activity might be.Key aims: The aims of the project are: 1. To investigate the means by which human mast cells are activated by IL-33 alone and in synergism with the ATP/ADP pathways and to define the nature of the IL-33-induced secretome.2. To study both the effect of IL-33 on the pattern of mast cell P1 and P2 receptor expression and the reciprocal effect of ATP/ADP pathway on IL-33R expression and IL-33 protein processing and signalling in human mast cells.3. Investigate the consequences of human mast cell activation via IL-33, in synergy with ATP/ADP, on human innate lymphocyte (ILC) 2 behaviour.Potential outcomes: The study is likely to provide new understanding of the biological basis of IL-33 activities on human mast cells. Training: Methodologically, the project will include culturing and differentiation of human mast cells and other cell lines and the evaluation of their function by state-of-the-art flow cytometry, advanced immunofluorescence, transcriptomic analysis, deep immunophenotyping and metabolic/proteomic approaches.