Targeting gasdermin D to treat myelodysplastic syndromes

摘要 调节失调的先天免疫系统和炎症体激活所致的骨髓炎症 越来越多的研究表明在骨髓增生异常综合征(MDS)的发病和进展中起关键作用。 尽管过去几年在这一领域取得了重大进展，但一个关键的悬而未决的问题是： 是调节骨髓炎发展的主要调节因子。解决这个问题 对于开发新的免疫疗法来治疗MDS并防止其进展至关重要，这 仍然是一个严重的未得到满足的医疗需求。使用Diap1和Diap1双基因敲除(DKO)的小鼠模型 MiR146a，两者都参与先天免疫信号，并在MDS患者中显著下调， 我们发现，老年DKO小鼠发生MDS是由于促炎细胞因子在 骨髓。DKO模型的一个独特特征是这些小鼠在 更年轻，但会发展成MDS，最终随着年龄的增长而进展为白血病，这与 MDS在患者中的发生发展。最近，我们发现IL-6的遗传耗竭在 DKO小鼠显著延缓了MDS的进展。然而，IL-6是一种高度上调的细胞因子 DKO小鼠和MDS患者。IL-6的丢失未能逆转炎性骨髓微环境 DKO模型中的许多MDS表型。有必要透露一下常见的上游监管者(S) 调节炎性细胞因子的释放。在这方面，IL-6是众所周知的IL-1的下游靶点， 它是由炎症诱导的嗜热性细胞释放的。炎症小体组装时会激活下睑下垂 包括nlrp3，nlrp3是nf-b的下游靶点，通过激活天然免疫而上调。 发信号。NLRP3的激活是MDS的一个独立于突变状态的标志。上调并激活 NLRP3炎症体激活caspase 1，进而裂解Gasdermin D。裂解Gasdermin D结果 在细胞通透性增加、下垂和包括IL-1家族在内的细胞因子的释放方面。鉴于它的核心作用 在上睑下垂中，Gasdermin D也可能参与MDS的发生和发展。因此，我们 将DKO小鼠与Gasdermin D基因敲除小鼠杂交。事实上，失去Gasdermin D显著恢复了MDS DKO小鼠的表型。Gasdermin D在MDS患者中也高度上调。我们的预赛 研究表明，Gasdermin D还介导了骨髓基质细胞的炎症。基于这些 数据，我们假设Gasdermin D介导炎症信号和先天免疫失调 造血细胞和骨髓基质细胞中的信号转导在促进MDS的发展和 进步。为了验证这一假设，我们将在以下三个目标上进行实验。在目标1中，我们将 探讨Gasdermin D在MDS发生发展中的造血细胞内在机制。 目的2分析Gasdermin D在炎性骨髓微环境中的作用。 目标3将通过靶向Gasdermin D治疗MDS来关注翻译方面的问题。成功完成 这将对了解衰老相关骨髓的发病机制有重要影响。 MDS的炎症和开发治疗MDS的新免疫疗法。

Summary Bone marrow inflammation induced by the dysregulated innate immune system and inflammasome activation is increasingly indicated to be critical in the pathogenesis and progression of myelodysplastic syndromes (MDS). Despite the significant progress in this field in the past few years, one of the key unresolved questions is: what are the major regulators that mediate the development of bone marrow inflammation. Resolving this question will be critical for the development of novel immunotherapies to treat MDS and prevent its progression, which remains to be a critical unmet medical need. Using a mouse model of double knockout (DKO) of Diap1 and miR146a, both are involved in the innate immune signaling and significantly downregulated in patients with MDS, we revealed that the old DKO mice developed MDS due to the upregulation of pro-inflammatory cytokines in the bone marrow. One of the unique features of the DKO model is that these mice are phenotypically normal at younger age but develop MDS that eventually progress to leukemia with aging, which closely phenocopies the development and progression of MDS in patients. More recently, we showed that genetic depletion of IL-6 in the DKO mice significantly delayed MDS progression. However, IL-6 is one of the highly upregulated cytokines in DKO mice and MDS patients. Loss of IL-6 failed to revert the inflammatory bone marrow microenvironment and many MDS phenotypes in the DKO model. It is essential to reveal the common upstream regulator(s) that mediate the release of inflammatory cytokines. In this respect, IL-6 is a well-known downstream target of IL-1, which is released by inflammation induced pyroptotic cells. Pyroptosis is activated upon inflammasome assembly including NLRP3, which is a downstream target of NF-b and upregulated by the activation of the innate immune signaling. Activation of NLRP3 is a hall mark of MDS independent of mutation status. Upregulated and activated NLRP3 inflammasome activates caspase 1, which in turn cleaves gasdermin D. The cleaved gasdermin D results in increased cell permeability, pyroptosis, and the release of cytokines including IL-1 family. Given its central role in pyroptosis, gasdermin D could also be involved in the pathogenesis and progression of MDS. We therefore crossed DKO mice with gasdermin D knockout mice. Indeed, loss of gasdermin D markedly reverted MDS phenotypes in the DKO mice. Gasdermin D is also highly upregulated in patients with MDS. Our preliminary studies indicate that gasdermin D also mediates inflammation in bone marrow stromal cells. Based on these data, we hypothesize that gasdermin D mediated inflammatory cues and dysregulation of innate immune signaling in hematopoietic cells and bone marrow stromal cells are pivotal in facilitating MDS development and progression. To test this hypothesis, we will perform experiments in the following three aims. In aim 1, we will investigate the hematopoietic cell intrinsic mechanisms of gasdermin D in MDS development and progression. In aim 2, the role of gasdermin D in mediating the inflammatory bone marrow microenvironment will be analyzed. Aim 3 will focus on the translational respect through targeting gasdermin D to treat MDS. Successful completion of this project will have an important impact in understanding the pathogenesis of aging associated bone marrow inflammation in MDS and developing novel immunotherapies to treat MDS.