Macrophage inflammasome regulation

描述（由申请人提供）：最近发现了不同的细胞内病原体识别受体，可以检测进入巨噬细胞细胞质的危险信号，这提高了先天免疫在肺防御外部挑战中的重要性。这些受体包括NOD样受体（nlr）以及与NOD无关的传感器，如pyrin。细胞内传感器的一个关键功能是通过炎性体复合物调节caspase-1酶。在炎性小体中，nlr和nod无关的传感器通过pyrin结构域（PYD）或caspase募集结构域（CARD）与适配蛋白ASC相互作用，诱导caspase-1二聚化和自激活。然后Caspase-1切割并激活IL-1和IL-18的前体，这些分子与哮喘、急性呼吸窘迫综合征、肺炎和肺纤维化密切相关。然而，尽管在概念上取得了进步，但这种炎性体复合物与IL-1的加工和释放之间的物理联系仍然不清楚，这限制了我们对肺部炎症的理解和创造新疗法的能力。在这种情况下，本应用旨在通过将其结构和功能与促进无领导蛋白IL-1释放的机制联系起来，扩展炎性体假说。我们提出了一种新的结构，释放体。我们假设这种新的外泌体结构将proIL-1¿和炎性小体成分包裹在肌动蛋白丝调节的囊泡中。Pyrin和ASC是已知的肌动蛋白结合蛋白。因此，在该模型中，微泡IL-1¿以高度浓缩的包形式呈现给靶细胞膜（例如肺成纤维细胞或上皮细胞），其继发性胞吐可以通过调节局部ATP浓度的靶细胞受体来控制（ATP是一种经典的炎性体激活因子）。该项目拟验证以下具体假设：1)IL-1主要由外泌体释放；2)靶细胞诱导的这些外泌体破裂提供了一种聚焦IL-1活性的机制；3) pyrin和ASC相互作用调节caspase-1的外泌体包装释放；4)肌动蛋白与proIL-1¿的相互作用对于外泌体炎性体proIL-1¿的相互作用至关重要。如果得到证实，这些新的假设将改变我们对IL-1调节的概念，并为炎症性肺疾病提供新的治疗选择。

DESCRIPTION (provided by applicant): Innate immunity's importance in lung defense against external challenges has been heightened by the recent discovery of distinct intracellular pathogen recognition receptors that detect danger signals that gain access to the cytosol of macrophages. These receptors include NOD-like receptors (NLRs) as well as NOD independent sensors such as pyrin. A critical function of the intracellular sensors is to regulate the enzyme caspase-1 through an inflammasome complex. In an inflammasome, NLRs and NOD-independent sensors interact, via pyrin domains (PYD) or caspase recruitment domains (CARD), with an adaptor protein, ASC, to induce caspase-1 dimerization and autoactivation. Caspase-1 then cleaves and activates the precursors of IL-1¿ and IL-18, molecules that have been strongly associated with asthma, ARDS, pneumonia and pulmonary fibrosis. However, despite this conceptual advance, it remains obscure how this inflammasome complex is physically linked to IL-1¿ processing and release, limiting our understanding of lung inflammation and our ability to create new therapies. In this context, the present application seeks to expand upon the inflammasome hypothesis by linking its structure and function to the mechanisms that promote the release of the leaderless protein IL-1¿. We propose a novel structure, the releasosome. We hypothesize that this novel exosomal structure encapsulates proIL-1¿ together with inflammasome components in an actin filament regulated vesicle. Pyrin and ASC are known actin binding proteins. Thus, in this model, microvesicular IL-1¿ is presented to target cell membranes (e.g. lung fibroblasts or epithelium) in a highly concentrated packet where its secondary exocytosis can be controlled by target cell receptors that modulate local concentrations of ATP (a classical inflammasome activating factor). The project proposes to test the following specific hypotheses, 1) IL-1¿ release is predominantly from exosomes; 2) the target cell induced rupture of these exosomes provides a mechanism to focus IL-1¿ activity; 3) pyrin and ASC interactions modulate the exosomal packaging of caspase-1 for release; and 4) actin interactions with proIL-1¿ are critical to exosomal inflammasome proIL-1¿ interaction. If confirmed, these novel hypotheses will change our concepts about IL-1¿ regulation and provide new treatment options for inflammatory lung disorders.