Identification and characterization of the mechanisms and relevance of inflammasome activation in mast cells

传统上，肥大细胞（MCs）主要被视为适应性免疫系统的效应细胞，因为它们可以介导过敏原诱导的IgE交联反应。然而，MCs正在成为先天免疫反应的关键贡献者：它们表达大量的先天免疫信号受体，包括toll样受体（TLR）家族的大多数成员，Rig-I样受体和nod样受体。与巨噬细胞和树突状细胞类似，MCs可以被来自病原体的危险信号激活，并且它们可以感知组织损伤过程中出现的改变的宿主分子。炎性小体是一类重要的先天性免疫传感器，可感知此类危险信号。通过白细胞介素1 β (IL-1 β)，它们在组织损伤期间通过感知许多内源性分子来驱动早期炎症反应，这些内源性分子在细胞应激或细菌感染期间被错误定位而改变。西方社会的许多流行疾病，包括慢性阻塞性肺病、代谢综合征、动脉粥样硬化和阿尔茨海默病，都受到炎症小体（如NLRP3）错误激活的影响，NLRP3现在被认为是一个有希望的治疗靶点。最近的研究强调了MC炎性体激活对自身炎症患者皮肤病变发展的重要性。到目前为止，还没有研究MC炎性小体在这些情况下活化的重要性。慢性伤口，并发细菌重复感染，呈现出日益增加的医疗和经济负担，在老龄化的西方社会发病率为2%。慢性伤口感染与肥大细胞和炎性体介质如IL-1 β的激活增加有关。紫外线照射是一种无菌炎性小体激活剂，可引起mc介导的炎症，这与黑色素瘤的发展有关。因此，我们有兴趣研究在这两种情况下MCs和炎性体激活之间的联系。我们的初步数据表明，人和小鼠MCs表达了广泛的功能性炎性小体，并且它们对炎性小体的刺激作出独立于组胺释放的反应。在此，我们建议在炎症小体报告小鼠（m-ASC-cerulean）的帮助下，研究mc依赖性炎症模型中炎症小体的激活途径。其次，我们将用缺乏不同炎症小体的MCs选择性重建mc缺陷小鼠，以确定特定炎症小体在疾病发展中的作用。然后，我们将评估MC炎性体激活在人类皮肤炎症中的相关性。最后，作为原理证明，我们将测试高通量筛选鉴定的小分子作为炎性体激活抑制剂对MCs的影响。因此，我们的目标是迅速转化我们的发现，并为MC和炎症小体相关的皮肤疾病提供新的治疗前景。

Traditionally, mast cells (MCs) are seen mainly as effector cells of the adaptive immune system, since they can mediate anaphylactic reactions upon allergen-induced IgE crosslinking. However, MCs are emerging as key contributors to innate immune responses: They express a large repertoire of innate immune signaling receptors, including most members of the Toll-like receptor (TLR) family, Rig-I like receptors and Nod-like receptors. Similar to macrophages and dendritic cells, MCs can be activated by danger signals derived from pathogens, and they can sense altered host molecules that appear during tissue damage. Inflammasomes are an important class of innate immunity sensors for such danger signals. Via Interleukin 1 beta (IL-1 beta), they drive early inflammatory responses during tissue damage by sensing many endogenous molecules that are altered by cell stress or mislocalized during bacterial infection. Many prevalent diseases in Western societies, including chronic obstructive pulmonary disease, metabolic syndrome, atherosclerosis and Alzheimer disease are influenced by erroneous activation of inflammasomes such as NLRP3, which is now considered a promising therapeutic target. Recent studies have highlighted the importance of MC inflammasome activation for the development of skin lesions in patients with autoinflammatory conditions. The importance of MC inflammasome activation beyond these conditions has so far not been studied. Chronic wounds, complicated by bacterial superinfection, present an increasing medical and economic burden with an incidence of 2% in aging Western societies. Chronic wound infections are associated with increased activation of mast cells and inflammasome mediators such as IL-1 beta. UV-irradiation is a sterile inflammasome activator and causes MC-mediated inflammation that is linked to the development of melanoma. We are, therefore, interested in studying the connection between MCs and inflammasome activation in these two conditions. Our preliminary data show that human and mouse MCs express a wide range of functional inflammasomes and that they respond towards inflammasome stimuli independently of histamine release. We, here, propose to study the pathways of inflammasome activation in MC-dependent models of inflammation with the help of an inflammasome reporter mouse (m-ASC-cerulean). Secondly, we will reconstitute MC-deficient mice selectively with MCs that lack different inflammasomes to identify the role of specific inflammasomes in disease development. We will then assess the relevance of MC inflammasome activation in human skin inflammation. Finally, as a proof of principle, we will test the effect of small molecules identified by high throughput screens as inflammasome activation mosulators on MCs. We thereby aim to swiftly translate our findings and generate new therapeutic perspectives for MC- and inflammasome-related skin diseases.